40 results on '"Caino MC"'
Search Results
2. MIRO2 regulates prostate cancer cell growth via GCN1-dependent stress signaling
- Author
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Furnish M, Lina Romero, Boulton Dp, Ellinwood Ml, Genther, Scott D. Cramer, Caino Mc, and Lucia Ms
- Subjects
Prostate cancer ,Downregulation and upregulation ,Kinase ,Cell growth ,ATF4 ,Cancer research ,medicine ,Context (language use) ,Biology ,Cell cycle ,medicine.disease ,Transcription factor - Abstract
There is a continued need to identify novel therapeutic targets to prevent the mortality associated with prostate cancer. In this context, we discovered a novel mitochondrial signaling pathway that controls androgen-independent and androgen-sensitive prostate cancer cell growth. Mitochondrial Rho GTPase 2 (MIRO2) mRNA was upregulated in prostate cancer compared to localized tumors, and higher MIRO2 levels were correlated with poor patient survival. Using human cell lines that represent AR-independent or androgen-sensitive prostate cancer, we show that MIRO2 depletion impaired cell growth, colony formation and tumor growth in mice. Network analysis of MIRO2’s binding partners identified metabolism, cell cycle, and cellular responses to extracellular stimuli amongst the top over-represented pathways. The top hit on our screen was General Control Non-derepressible 1 (GCN1). GCN1 was overexpressed in prostate cancer and MIRO2-GCN1 interacted in prostate cancer cell lines and in primary prostate cancer cells. Our results showed that MIRO2 is necessary for efficient GCN1-mediated GCN2 kinase activation and signaling, triggering translation of the transcription factor ATF4. Importantly, MIRO2 controlled ATF4 levels and transcriptional activity both in amino acid replete and depleted conditions. Furthermore, MIRO2’s effect on regulating prostate cancer cell growth was partially mediated by ATF4. Finally, activation of GCN2 and ATF4 expression were correlated with MIRO2 expression in prostate cancer xenografts. Overall, we propose a new mechanism driving prostate cancer growth of both AR-independent and androgen-sensitive tumors.
- Published
- 2021
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3. Emerging roles for Mitochondrial Rho GTPases in tumor biology.
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Boulton DP and Caino MC
- Subjects
- Humans, Animals, Tumor Microenvironment, Mitochondrial Proteins metabolism, Mitochondrial Proteins genetics, rho GTP-Binding Proteins metabolism, rho GTP-Binding Proteins genetics, Neoplasms metabolism, Neoplasms pathology, Neoplasms genetics, Mitochondria metabolism, Mitochondria pathology
- Abstract
Mitochondrial Rho GTPases (MIRO1 and MIRO2) are primarily studied for their role as resident mitochondrial anchor proteins that facilitate mitochondria trafficking in neurons. However, it is now appreciated that these proteins have critical roles in cancer. In this review, we focus on examining the role of MIROs in cancer, including expression changes in tumors and the molecular mechanisms by which MIROs impact tumor cell growth, invasion, and metastasis. Additionally, we give an overview of how MIRO's functions in normal cells within the tumor microenvironment can support or inhibit tumor growth and metastasis. Although this is still an emerging field, the current consensus is that the MIROs primarily promote tumor progression of disparate tumor types. As mitochondrial proteins are now being targeted in the clinic, we discuss their potential as novel proteins to target in cancer., Competing Interests: Conflict of interest The authors declare no conflict of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2024
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4. Metabolic reprogramming contributes to radioprotection by protein kinase Cδ.
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Ohm AM, Affandi T, Reisz JA, Caino MC, D'Alessandro A, and Reyland ME
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- Humans, Glucose metabolism, Glutamine metabolism, Glycolysis, Pentose Phosphate Pathway genetics, Animals, Rats, A549 Cells, Cell Line, Up-Regulation, Enzyme Activation, Nucleotides biosynthesis, Metabolic Reprogramming, Protein Kinase C-delta metabolism, Protein Kinase C-delta genetics, Radiation Tolerance genetics
- Abstract
Loss of protein kinase Cδ (PKCδ) activity renders cells resistant to DNA damaging agents, including irradiation; however, the mechanism(s) underlying resistance is poorly understood. Here, we have asked if metabolic reprogramming by PKCδ contributes to radioprotection. Analysis of global metabolomics showed that depletion of PKCδ affects metabolic pathways that control energy production and antioxidant, nucleotide, and amino acid biosynthesis. Increased NADPH and nucleotide production in PKCδ-depleted cells is associated with upregulation of the pentose phosphate pathway (PPP) as evidenced by increased activation of G6PD and an increase in the nucleotide precursor, 5-phosphoribosyl-1-pyrophosphate. Stable isotope tracing with U-[
13 C6 ] glucose showed reduced utilization of glucose for glycolysis in PKCδ-depleted cells and no increase in U-[13 C6 ] glucose incorporation into purines or pyrimidines. In contrast, isotope tracing with [13 C5 ,15 N2 ] glutamine showed increased utilization of glutamine for synthesis of nucleotides, glutathione, and tricarboxylic acid intermediates and increased incorporation of labeled glutamine into pyruvate and lactate. Using a glycolytic rate assay, we confirmed that anaerobic glycolysis is increased in PKCδ-depleted cells; this was accompanied by a reduction in oxidative phosphorylation, as assayed using a mitochondrial stress assay. Importantly, pretreatment of cells with specific inhibitors of the PPP or glutaminase prior to irradiation reversed radioprotection in PKCδ-depleted cells, indicating that these cells have acquired codependency on the PPP and glutamine for survival. Our studies demonstrate that metabolic reprogramming to increase utilization of glutamine and nucleotide synthesis contributes to radioprotection in the context of PKCδ inhibition., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)- Published
- 2023
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5. Parkin ubiquitination of Kindlin-2 enables mitochondria-associated metastasis suppression.
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Yeon M, Bertolini I, Agarwal E, Ghosh JC, Tang HY, Speicher DW, Keeney F, Sossey-Alaoui K, Pluskota E, Bialkowska K, Plow EF, Languino LR, Skordalakes E, Caino MC, and Altieri DC
- Subjects
- Cell Movement, Mitochondria metabolism, Ubiquitination, Humans, Membrane Proteins metabolism, Ubiquitin-Protein Ligases metabolism
- Abstract
Mitochondria are signaling organelles implicated in cancer, but the mechanisms are elusive. Here, we show that Parkin, an E3 ubiquitination (Ub) ligase altered in Parkinson's disease, forms a complex with the regulator of cell motility, Kindlin-2 (K2), at mitochondria of tumor cells. In turn, Parkin ubiquitinates Lys581 and Lys582 using Lys48 linkages, resulting in proteasomal degradation of K2 and shortened half-life from ∼5 h to ∼1.5 h. Loss of K2 inhibits focal adhesion turnover and β1 integrin activation, impairs membrane lamellipodia size and frequency, and inhibits mitochondrial dynamics, altogether suppressing tumor cell-extracellular matrix interactions, migration, and invasion. Conversely, Parkin does not affect tumor cell proliferation, cell cycle transitions, or apoptosis. Expression of a Parkin Ub-resistant K2 Lys581Ala/Lys582Ala double mutant is sufficient to restore membrane lamellipodia dynamics, correct mitochondrial fusion/fission, and preserve single-cell migration and invasion. In a 3D model of mammary gland developmental morphogenesis, impaired K2 Ub drives multiple oncogenic traits of EMT, increased cell proliferation, reduced apoptosis, and disrupted basal-apical polarity. Therefore, deregulated K2 is a potent oncogene, and its Ub by Parkin enables mitochondria-associated metastasis suppression., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
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6. NPC1 Confers Metabolic Flexibility in Triple Negative Breast Cancer.
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O'Neill KI, Kuo LW, Williams MM, Lind H, Crump LS, Hammond NG, Spoelstra NS, Caino MC, and Richer JK
- Abstract
Triple-negative breast cancer (TNBC) often undergoes at least partial epithelial-to-mesenchymal transition (EMT) to facilitate metastasis. Identifying EMT-associated characteristics can reveal novel dependencies that may serve as therapeutic vulnerabilities in this aggressive breast cancer subtype. We found that NPC1 , which encodes the lysosomal cholesterol transporter Niemann-Pick type C1 is highly expressed in TNBC as compared to estrogen receptor-positive (ER+) breast cancer, and is significantly elevated in high-grade disease. We demonstrated that NPC1 is directly targeted by microRNA-200c (miR-200c), a potent suppressor of EMT, providing a mechanism for its differential expression in breast cancer subtypes. The silencing of NPC1 in TNBC causes an accumulation of cholesterol-filled lysosomes, and drives decreased growth in soft agar and invasive capacity. Conversely, overexpression of NPC1 in an ER+ cell line increases invasion and growth in soft agar. We further identified TNBC cell lines as cholesterol auxotrophs, however, they do not solely depend on NPC1 for adequate cholesterol supply. The silencing of NPC1 in TNBC cell lines led to altered mitochondrial function and morphology, suppression of mTOR signaling, and accumulation of autophagosomes. A small molecule inhibitor of NPC1, U18666A, decreased TNBC proliferation and synergized with the chemotherapeutic drug, paclitaxel. This work suggests that NPC1 promotes aggressive characteristics in TNBC, and identifies NPC1 as a potential therapeutic target.
- Published
- 2022
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7. MIRO2 Regulates Prostate Cancer Cell Growth via GCN1-Dependent Stress Signaling.
- Author
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Furnish M, Boulton DP, Genther V, Grofova D, Ellinwood ML, Romero L, Lucia MS, Cramer SD, and Caino MC
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- Animals, Humans, Male, Mice, Peptide Elongation Factors genetics, Peptide Elongation Factors metabolism, Protein Serine-Threonine Kinases, RNA-Binding Proteins metabolism, Signal Transduction, Trans-Activators metabolism, Prostatic Neoplasms genetics
- Abstract
There is a continued need to identify novel therapeutic targets to prevent the mortality associated with prostate cancer. In this context, mitochondrial Rho GTPase 2 (MIRO2) mRNA was upregulated in metastatic prostate cancer compared with localized tumors, and higher MIRO2 levels were correlated with poor patient survival. Using human cell lines that represent androgen-independent or -sensitive prostate cancer, we showed that MIRO2 depletion impaired cell growth, colony formation, and tumor growth in mice. Network analysis of MIRO2's binding partners identified metabolism and cellular responses to extracellular stimuli as top overrepresented pathways. The top hit on our screen, General Control Nonderepressible 1 (GCN1), was overexpressed in prostate cancer, and interacted with MIRO2 in prostate cancer cell lines and in primary prostate cancer cells. Functional analysis of MIRO2 mutations present in patients with prostate cancer led to the identification of MIRO2 159L, which increased GCN1 binding. Importantly, MIRO2 was necessary for efficient GCN1-mediated GCN2 kinase signaling and induction of the transcription factor activating transcription factor 4 (ATF4) levels. Further, MIRO2's effect on regulating prostate cancer cell growth was mediated by ATF4. Finally, levels of activated GCN2 and ATF4 were correlated with MIRO2 expression in prostate cancer xenografts. Both MIRO2 and activated GCN2 levels were higher in hypoxic areas of prostate cancer xenografts. Overall, we propose that targeting the MIRO2-GCN1 axis may be a valuable strategy to halt prostate cancer growth., Implications: MIRO2/GCN1/GCN2 constitute a novel mitochondrial signaling pathway that controls androgen-independent and androgen-sensitive prostate cancer cell growth., (©2022 The Authors; Published by the American Association for Cancer Research.)
- Published
- 2022
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8. Mitochondrial Fission and Fusion in Tumor Progression to Metastasis.
- Author
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Boulton DP and Caino MC
- Abstract
Mitochondria are highly dynamic organelles which can change their shape, via processes termed fission and fusion, in order to adapt to different environmental and developmental contexts. Due to the importance of these processes in maintaining a physiologically healthy pool of mitochondria, aberrant cycles of fission/fusion are often seen in pathological contexts. In this review we will discuss how dysregulated fission and fusion promote tumor progression. We focus on the molecular mechanisms involved in fission and fusion, discussing how altered mitochondrial fission and fusion change tumor cell growth, metabolism, motility, and invasion and, finally how changes to these tumor-cell intrinsic phenotypes directly and indirectly impact tumor progression to metastasis. Although this is an emerging field of investigation, the current consensus is that mitochondrial fission positively influences metastatic potential in a broad variety of tumor types. As mitochondria are now being investigated as vulnerable targets in a variety of cancer types, we underscore the importance of their dynamic nature in potentiating tumor progression., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Boulton and Caino.)
- Published
- 2022
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9. Ghost mitochondria drive metastasis through adaptive GCN2/Akt therapeutic vulnerability.
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Ghosh JC, Perego M, Agarwal E, Bertolini I, Wang Y, Goldman AR, Tang HY, Kossenkov AV, Landis CJ, Languino LR, Plow EF, Morotti A, Ottobrini L, Locatelli M, Speicher DW, Caino MC, Cassel J, Salvino JM, Robert ME, Vaira V, and Altieri DC
- Subjects
- Cell Death, Cell Line, Tumor, Cell Movement genetics, Cell Proliferation, Epithelial-Mesenchymal Transition, Humans, Mitochondria metabolism, Mitochondrial Dynamics physiology, Mitochondrial Proteins metabolism, Muscle Proteins metabolism, Neoplasm Invasiveness genetics, Neoplasms metabolism, Neoplasms physiopathology, Neoplastic Processes, Protein Serine-Threonine Kinases metabolism, Proto-Oncogene Proteins c-akt metabolism, Reactive Oxygen Species, Signal Transduction, Mitochondria physiology, Neoplasm Metastasis physiopathology, Neoplasms genetics
- Abstract
Cancer metabolism, including in mitochondria, is a disease hallmark and therapeutic target, but its regulation is poorly understood. Here, we show that many human tumors have heterogeneous and often reduced levels of Mic60, or Mitofilin, an essential scaffold of mitochondrial structure. Despite a catastrophic collapse of mitochondrial integrity, loss of bioenergetics, and oxidative damage, tumors with Mic60 depletion slow down cell proliferation, evade cell death, and activate a nuclear gene expression program of innate immunity and cytokine/chemokine signaling. In turn, this induces epithelial-mesenchymal transition (EMT), activates tumor cell movements through exaggerated mitochondrial dynamics, and promotes metastatic dissemination in vivo. In a small-molecule drug screen, compensatory activation of stress response (GCN2) and survival (Akt) signaling maintains the viability of Mic60-low tumors and provides a selective therapeutic vulnerability. These data demonstrate that acutely damaged, "ghost" mitochondria drive tumor progression and expose an actionable therapeutic target in metastasis-prone cancers., Competing Interests: The authors declare no competing interest.
- Published
- 2022
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10. Mitochondrial-derived vesicles compensate for loss of LC3-mediated mitophagy.
- Author
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Towers CG, Wodetzki DK, Thorburn J, Smith KR, Caino MC, and Thorburn A
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- Autophagy-Related Protein 7 genetics, Autophagy-Related Protein 7 metabolism, Autophagy-Related Proteins genetics, Autophagy-Related Proteins metabolism, Endosomes metabolism, Humans, Lysosomes, Microtubule-Associated Proteins genetics, Mitochondria metabolism, Sorting Nexins genetics, Autophagy, Microtubule-Associated Proteins metabolism, Mitochondria pathology, Mitochondrial Dynamics, Mitophagy, Sorting Nexins metabolism, Transport Vesicles physiology
- Abstract
Mitochondria are critical metabolic and signaling hubs, and dysregulated mitochondrial homeostasis is implicated in many diseases. Degradation of damaged mitochondria by selective GABARAP/LC3-dependent macro-autophagy (mitophagy) is critical for maintaining mitochondrial homeostasis. To identify alternate forms of mitochondrial quality control that functionally compensate if mitophagy is inactive, we selected for autophagy-dependent cancer cells that survived loss of LC3-dependent autophagosome formation caused by inactivation of ATG7 or RB1CC1/FIP200. We discovered rare surviving autophagy-deficient clones that adapted to maintain mitochondrial homeostasis after gene inactivation and identified two enhanced mechanisms affecting mitochondria including mitochondrial dynamics and mitochondrial-derived vesicles (MDVs). To further understand these mechanisms, we quantified MDVs via flow cytometry and confirmed an SNX9-mediated mechanism necessary for flux of MDVs to lysosomes. We show that the autophagy-dependent cells acquire unique dependencies on these processes, indicating that these alternate forms of mitochondrial homeostasis compensate for loss of autophagy to maintain mitochondrial health., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 Elsevier Inc. All rights reserved.)
- Published
- 2021
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11. Changes in Aged Fibroblast Lipid Metabolism Induce Age-Dependent Melanoma Cell Resistance to Targeted Therapy via the Fatty Acid Transporter FATP2.
- Author
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Alicea GM, Rebecca VW, Goldman AR, Fane ME, Douglass SM, Behera R, Webster MR, Kugel CH 3rd, Ecker BL, Caino MC, Kossenkov AV, Tang HY, Frederick DT, Flaherty KT, Xu X, Liu Q, Gabrilovich DI, Herlyn M, Blair IA, Schug ZT, Speicher DW, and Weeraratna AT
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- Antineoplastic Combined Chemotherapy Protocols therapeutic use, Cell Line, Tumor, Cellular Senescence, Coculture Techniques, Coenzyme A Ligases antagonists & inhibitors, Dermis cytology, Dermis pathology, Drug Resistance, Neoplasm drug effects, Humans, Keratinocytes metabolism, Lipid Metabolism, Melanoma pathology, Molecular Targeted Therapy methods, Protein Kinase Inhibitors pharmacology, Protein Kinase Inhibitors therapeutic use, Skin Neoplasms pathology, Tumor Microenvironment, Antineoplastic Combined Chemotherapy Protocols pharmacology, Coenzyme A Ligases metabolism, Fibroblasts metabolism, Melanoma drug therapy, Skin Neoplasms drug therapy
- Abstract
Older patients with melanoma (>50 years old) have poorer prognoses and response rates to targeted therapy compared with young patients (<50 years old), which can be driven, in part, by the aged microenvironment. Here, we show that aged dermal fibroblasts increase the secretion of neutral lipids, especially ceramides. When melanoma cells are exposed to the aged fibroblast lipid secretome, or cocultured with aged fibroblasts, they increase the uptake of lipids via the fatty acid transporter FATP2, which is upregulated in melanoma cells in the aged microenvironment and known to play roles in lipid synthesis and accumulation. We show that blocking FATP2 in melanoma cells in an aged microenvironment inhibits their accumulation of lipids and disrupts their mitochondrial metabolism. Inhibiting FATP2 overcomes age-related resistance to BRAF/MEK inhibition in animal models, ablates tumor relapse, and significantly extends survival time in older animals. SIGNIFICANCE: These data show that melanoma cells take up lipids from aged fibroblasts, via FATP2, and use them to resist targeted therapy. The response to targeted therapy is altered in aged individuals because of the influences of the aged microenvironment, and these data suggest FATP2 as a target to overcome resistance. See related commentary by Montal and White, p. 1255 . This article is highlighted in the In This Issue feature, p. 1241 ., (©2020 American Association for Cancer Research.)
- Published
- 2020
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12. The mitophagy effector FUNDC1 controls mitochondrial reprogramming and cellular plasticity in cancer cells.
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Li J, Agarwal E, Bertolini I, Seo JH, Caino MC, Ghosh JC, Kossenkov AV, Liu Q, Tang HY, Goldman AR, Languino LR, Speicher DW, and Altieri DC
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- A549 Cells, Animals, Humans, MCF-7 Cells, Membrane Proteins genetics, Mice, Mitochondrial Proteins genetics, NIH 3T3 Cells, Neoplasm Proteins genetics, Neoplasms genetics, PC-3 Cells, Membrane Proteins metabolism, Mitochondria metabolism, Mitochondrial Proteins metabolism, Mitophagy, Neoplasm Proteins metabolism, Neoplasms metabolism
- Abstract
Mitochondria are signaling hubs in eukaryotic cells. Here, we showed that the mitochondrial FUN14 domain-containing protein-1 (FUNDC1), an effector of Parkin-independent mitophagy, also participates in cellular plasticity by sustaining oxidative bioenergetics, buffering ROS production, and supporting cell proliferation. Targeting this pathway in cancer cells suppressed tumor growth but rendered transformed cells more motile and invasive in a manner dependent on ROS-mediated mitochondrial dynamics and mitochondrial repositioning to the cortical cytoskeleton. Global metabolomics and proteomics profiling identified a FUNDC1 interactome at the mitochondrial inner membrane, comprising the AAA+ protease, LonP1, and subunits of oxidative phosphorylation, complex V (ATP synthase). Independently of its previously identified role in mitophagy, FUNDC1 enabled LonP1 proteostasis, which in turn preserved complex V function and decreased ROS generation. Therefore, mitochondrial reprogramming by a FUNDC1-LonP1 axis controls tumor cell plasticity by switching between proliferative and invasive states in cancer., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2020
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13. Androgen-induced expression of DRP1 regulates mitochondrial metabolic reprogramming in prostate cancer.
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Lee YG, Nam Y, Shin KJ, Yoon S, Park WS, Joung JY, Seo JK, Jang J, Lee S, Nam D, Caino MC, Suh PG, and Chan Chae Y
- Subjects
- Cell Line, Tumor, Cell Proliferation physiology, Citric Acid Cycle, Dihydrotestosterone pharmacology, Dynamins antagonists & inhibitors, Dynamins genetics, Dynamins metabolism, Gene Knockdown Techniques, Humans, Male, Mitochondrial Dynamics, Mitochondrial Membrane Transport Proteins metabolism, Oxidative Phosphorylation, PC-3 Cells, Prostatic Neoplasms, Castration-Resistant pathology, Pyruvates metabolism, Receptors, Androgen metabolism, Signal Transduction, Up-Regulation, Voltage-Dependent Anion Channels metabolism, Androgens metabolism, Dynamins biosynthesis, Mitochondria metabolism, Prostatic Neoplasms, Castration-Resistant metabolism
- Abstract
Androgen receptor (AR) signaling plays a central role in metabolic reprogramming for prostate cancer (PCa) growth and progression. Mitochondria are metabolic powerhouses of the cell and support several hallmarks of cancer. However, the molecular links between AR signaling and the mitochondria that support the metabolic demands of PCa cells are poorly understood. Here, we demonstrate increased levels of dynamin-related protein 1 (DRP1), a mitochondrial fission mediator, in androgen-sensitive and castration-resistant AR-driven PCa. AR signaling upregulates DRP1 to form the VDAC-MPC2 complex, increases pyruvate transport into mitochondria, and supports mitochondrial metabolism, including oxidative phosphorylation and lipogenesis. DRP1 inhibition activates the cellular metabolic stress response, which involves AMPK phosphorylation, induction of autophagy, and the ER unfolded protein response, and attenuates androgen-induced proliferation. Additionally, DRP1 expression facilitates PCa cell survival under diverse metabolic stress conditions, including hypoxia and oxidative stress. Moreover, we found that increased DRP1 expression was indicative of poor prognosis in patients with castration-resistant PCa. Collectively, our findings link androgen signaling-mediated mitochondrial dynamics to metabolic reprogramming; moreover, they have important implications for understanding PCa progression., (Copyright © 2019 Elsevier B.V. All rights reserved.)
- Published
- 2020
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14. Altered mitochondrial trafficking as a novel mechanism of cancer metastasis.
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Furnish M and Caino MC
- Subjects
- Adenosine Triphosphate metabolism, Animals, Cell Movement, Focal Adhesions, Humans, Membrane Proteins physiology, Microtubules physiology, Myosin Heavy Chains physiology, Myosin Type V physiology, Myosins physiology, Neoplasm Invasiveness, Nerve Tissue Proteins physiology, Signal Transduction, Mitochondria physiology, Neoplasm Metastasis
- Abstract
Background: Mammalian cells must constantly reprogram the distribution of mitochondria in order to meet the local demands for energy, calcium, redox balance, and other mitochondrial functions. Mitochondrial localization inside the cell is a result of a combination of movement along the microtubule tracks plus anchoring to actin filaments., Recent Findings: Recent advances show that subcellular distribution of mitochondria can regulate tumor cell growth, proliferation/motility plasticity, metastatic competence, and therapy responses in tumors. In this review, we discuss our current understanding of the mechanisms by which mitochondrial subcellular distribution is regulated in tumor cells., Conclusions: Mitochondrial trafficking is dysregulated in tumors. Accumulation of mitochondria at the leading edge of the cell supports energy expensive processes of focal adhesion dynamics, cell membrane dynamics, migration, and invasion., (© 2019 Wiley Periodicals, Inc.)
- Published
- 2020
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15. Syntaphilin Ubiquitination Regulates Mitochondrial Dynamics and Tumor Cell Movements.
- Author
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Seo JH, Agarwal E, Bryant KG, Caino MC, Kim ET, Kossenkov AV, Tang HY, Languino LR, Gabrilovich DI, Cohen AR, Speicher DW, and Altieri DC
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- Animals, Cell Line, Cell Line, Tumor, Cytoskeleton metabolism, Cytoskeleton physiology, Dynamins metabolism, Humans, Male, Membrane Proteins, Mice, Mice, Inbred C57BL, Mitochondria pathology, Mitochondrial Dynamics physiology, NIH 3T3 Cells, PC-3 Cells, Ubiquitin-Protein Ligases metabolism, Cell Movement physiology, Mitochondria metabolism, Neoplasms metabolism, Neoplasms pathology, Nerve Tissue Proteins metabolism, Ubiquitination physiology, Vesicular Transport Proteins metabolism
- Abstract
Syntaphilin (SNPH) inhibits the movement of mitochondria in tumor cells, preventing their accumulation at the cortical cytoskeleton and limiting the bioenergetics of cell motility and invasion. Although this may suppress metastasis, the regulation of the SNPH pathway is not well understood. Using a global proteomics screen, we show that SNPH associates with multiple regulators of ubiquitin-dependent responses and is ubiquitinated by the E3 ligase CHIP (or STUB1) on Lys111 and Lys153 in the microtubule-binding domain. SNPH ubiquitination did not result in protein degradation, but instead anchored SNPH on tubulin to inhibit mitochondrial motility and cycles of organelle fusion and fission, that is dynamics. Expression of ubiquitination-defective SNPH mutant Lys111→Arg or Lys153→Arg increased the speed and distance traveled by mitochondria, repositioned mitochondria to the cortical cytoskeleton, and supported heightened tumor chemotaxis, invasion, and metastasis in vivo Interference with SNPH ubiquitination activated mitochondrial dynamics, resulting in increased recruitment of the fission regulator dynamin-related protein-1 (Drp1) to mitochondria and Drp1-dependent tumor cell motility. These data uncover nondegradative ubiquitination of SNPH as a key regulator of mitochondrial trafficking and tumor cell motility and invasion. In this way, SNPH may function as a unique, ubiquitination-regulated suppressor of metastasis. Significance: These findings reveal a new mechanism of metastasis suppression by establishing the role of SNPH ubiquitination in inhibiting mitochondrial dynamics, chemotaxis, and metastasis. Cancer Res; 78(15); 4215-28. ©2018 AACR ., (©2018 American Association for Cancer Research.)
- Published
- 2018
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16. Mitochondrial Dynamics in Type 2 Diabetes and Cancer.
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Williams M and Caino MC
- Abstract
Mitochondria are bioenergetic, biosynthetic, and signaling organelles that control various aspects of cellular and organism homeostasis. Quality control mechanisms are in place to ensure maximal mitochondrial function and metabolic homeostasis at the cellular level. Dysregulation of these pathways is a common theme in human disease. In this mini-review, we discuss how alterations of the mitochondrial network influences mitochondrial function, focusing on the molecular regulators of mitochondrial dynamics (organelle's shape and localization). We highlight similarities and critical differences in the mitochondrial network of cancer and type 2 diabetes, which may be relevant for treatment of these diseases.
- Published
- 2018
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17. Syntaphilin controls a mitochondrial rheostat for proliferation-motility decisions in cancer.
- Author
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Caino MC, Seo JH, Wang Y, Rivadeneira DB, Gabrilovich DI, Kim ET, Weeraratna AT, Languino LR, and Altieri DC
- Subjects
- A549 Cells, Animals, Humans, MCF-7 Cells, Membrane Proteins, Mice, Microtubule-Associated Proteins genetics, Mitochondria genetics, Mitochondria pathology, NIH 3T3 Cells, Neoplasm Metastasis, Neoplasm Proteins genetics, Neoplasms genetics, Neoplasms pathology, Nerve Tissue Proteins genetics, Vesicular Transport Proteins genetics, Cell Proliferation, Microtubule-Associated Proteins metabolism, Mitochondria metabolism, Neoplasm Proteins metabolism, Neoplasms metabolism, Nerve Tissue Proteins metabolism, Vesicular Transport Proteins metabolism
- Abstract
Tumors adapt to an unfavorable microenvironment by controlling the balance between cell proliferation and cell motility, but the regulators of this process are largely unknown. Here, we show that an alternatively spliced isoform of syntaphilin (SNPH), a cytoskeletal regulator of mitochondrial movements in neurons, is directed to mitochondria of tumor cells. Mitochondrial SNPH buffers oxidative stress and maintains complex II-dependent bioenergetics, sustaining local tumor growth while restricting mitochondrial redistribution to the cortical cytoskeleton and tumor cell motility. Conversely, introduction of stress stimuli to the microenvironment, including hypoxia, acutely lowered SNPH levels, resulting in bioenergetics defects and increased superoxide production. In turn, this suppressed tumor cell proliferation but increased tumor cell invasion via greater mitochondrial trafficking to the cortical cytoskeleton. Loss of SNPH or expression of an SNPH mutant lacking the mitochondrial localization sequence resulted in increased metastatic dissemination in xenograft or syngeneic tumor models in vivo. Accordingly, tumor cells that acquired the ability to metastasize in vivo constitutively downregulated SNPH and exhibited higher oxidative stress, reduced cell proliferation, and increased cell motility. Therefore, SNPH is a stress-regulated mitochondrial switch of the cell proliferation-motility balance in cancer, and its pathway may represent a therapeutic target.
- Published
- 2017
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18. A neuronal network of mitochondrial dynamics regulates metastasis.
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Caino MC, Seo JH, Aguinaldo A, Wait E, Bryant KG, Kossenkov AV, Hayden JE, Vaira V, Morotti A, Ferrero S, Bosari S, Gabrilovich DI, Languino LR, Cohen AR, and Altieri DC
- Subjects
- Down-Regulation, Gene Expression Regulation, Neoplastic, Humans, Kinesins genetics, Membrane Proteins, Metabolic Networks and Pathways physiology, Mitochondrial Proteins genetics, rho GTP-Binding Proteins genetics, Kinesins metabolism, Mitochondrial Dynamics physiology, Mitochondrial Proteins metabolism, Neoplasm Metastasis physiopathology, Nerve Tissue Proteins metabolism, Vesicular Transport Proteins metabolism, rho GTP-Binding Proteins metabolism
- Abstract
The role of mitochondria in cancer is controversial. Using a genome-wide shRNA screen, we now show that tumours reprogram a network of mitochondrial dynamics operative in neurons, including syntaphilin (SNPH), kinesin KIF5B and GTPase Miro1/2 to localize mitochondria to the cortical cytoskeleton and power the membrane machinery of cell movements. When expressed in tumours, SNPH inhibits the speed and distance travelled by individual mitochondria, suppresses organelle dynamics, and blocks chemotaxis and metastasis, in vivo. Tumour progression in humans is associated with downregulation or loss of SNPH, which correlates with shortened patient survival, increased mitochondrial trafficking to the cortical cytoskeleton, greater membrane dynamics and heightened cell invasion. Therefore, a SNPH network regulates metastatic competence and may provide a therapeutic target in cancer.
- Published
- 2016
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19. Mitochondrial Akt Regulation of Hypoxic Tumor Reprogramming.
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Chae YC, Vaira V, Caino MC, Tang HY, Seo JH, Kossenkov AV, Ottobrini L, Martelli C, Lucignani G, Bertolini I, Locatelli M, Bryant KG, Ghosh JC, Lisanti S, Ku B, Bosari S, Languino LR, Speicher DW, and Altieri DC
- Subjects
- Animals, Cell Hypoxia physiology, Cell Line, Tumor, Cell Proliferation physiology, Female, Humans, Male, Mice, Mice, Inbred NOD, Mice, Nude, Protein Serine-Threonine Kinases metabolism, Pyruvate Dehydrogenase Acetyl-Transferring Kinase, Signal Transduction, Cellular Reprogramming physiology, Mitochondria metabolism, Neoplasms metabolism, Neoplasms pathology, Proto-Oncogene Proteins c-akt metabolism
- Abstract
Hypoxia is a universal driver of aggressive tumor behavior, but the underlying mechanisms are not completely understood. Using a phosphoproteomics screen, we now show that active Akt accumulates in the mitochondria during hypoxia and phosphorylates pyruvate dehydrogenase kinase 1 (PDK1) on Thr346 to inactivate the pyruvate dehydrogenase complex. In turn, this pathway switches tumor metabolism toward glycolysis, antagonizes apoptosis and autophagy, dampens oxidative stress, and maintains tumor cell proliferation in the face of severe hypoxia. Mitochondrial Akt-PDK1 signaling correlates with unfavorable prognostic markers and shorter survival in glioma patients and may provide an "actionable" therapeutic target in cancer., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
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20. The Mitochondrial Unfoldase-Peptidase Complex ClpXP Controls Bioenergetics Stress and Metastasis.
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Seo JH, Rivadeneira DB, Caino MC, Chae YC, Speicher DW, Tang HY, Vaira V, Bosari S, Palleschi A, Rampini P, Kossenkov AV, Languino LR, and Altieri DC
- Subjects
- Adult, Aged, Aged, 80 and over, Animals, Cell Line, Tumor, Endopeptidase Clp genetics, Female, Humans, Inhibitor of Apoptosis Proteins genetics, Inhibitor of Apoptosis Proteins metabolism, Male, Mice, Inbred NOD, Mice, Knockout, Mice, SCID, Middle Aged, Mitochondria genetics, Mitochondrial Proteins genetics, Neoplasm Metastasis, Neoplasms genetics, Neoplasms pathology, Protein Subunits genetics, Protein Subunits metabolism, Proteomics methods, RNA Interference, Succinate Dehydrogenase genetics, Succinate Dehydrogenase metabolism, Survivin, Transplantation, Heterologous, Endopeptidase Clp metabolism, Energy Metabolism, Mitochondria metabolism, Mitochondrial Proteins metabolism, Neoplasms metabolism
- Abstract
Mitochondria must buffer the risk of proteotoxic stress to preserve bioenergetics, but the role of these mechanisms in disease is poorly understood. Using a proteomics screen, we now show that the mitochondrial unfoldase-peptidase complex ClpXP associates with the oncoprotein survivin and the respiratory chain Complex II subunit succinate dehydrogenase B (SDHB) in mitochondria of tumor cells. Knockdown of ClpXP subunits ClpP or ClpX induces the accumulation of misfolded SDHB, impairing oxidative phosphorylation and ATP production while activating "stress" signals of 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and autophagy. Deregulated mitochondrial respiration induced by ClpXP targeting causes oxidative stress, which in turn reduces tumor cell proliferation, suppresses cell motility, and abolishes metastatic dissemination in vivo. ClpP is universally overexpressed in primary and metastatic human cancer, correlating with shortened patient survival. Therefore, tumors exploit ClpXP-directed proteostasis to maintain mitochondrial bioenergetics, buffer oxidative stress, and enable metastatic competence. This pathway may provide a "drugable" therapeutic target in cancer.
- Published
- 2016
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21. Molecular Pathways: Mitochondrial Reprogramming in Tumor Progression and Therapy.
- Author
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Caino MC and Altieri DC
- Subjects
- Adaptation, Biological, Animals, Antineoplastic Agents pharmacology, Antineoplastic Agents therapeutic use, Clinical Trials as Topic, Disease Progression, Drug Evaluation, Preclinical, Humans, Mitochondria drug effects, Molecular Targeted Therapy, Neoplasms pathology, Neoplasms therapy, Translational Research, Biomedical, Mitochondria metabolism, Neoplasms metabolism, Signal Transduction drug effects
- Abstract
Small-molecule inhibitors of the phosphoinositide 3-kinase (PI3K), Akt, and mTOR pathway currently in the clinic produce a paradoxical reactivation of the pathway they are intended to suppress. Furthermore, fresh experimental evidence with PI3K antagonists in melanoma, glioblastoma, and prostate cancer shows that mitochondrial metabolism drives an elaborate process of tumor adaptation culminating with drug resistance and metastatic competency. This is centered on reprogramming of mitochondrial functions to promote improved cell survival and to fuel the machinery of cell motility and invasion. Key players in these responses are molecular chaperones of the Hsp90 family compartmentalized in mitochondria, which suppress apoptosis via phosphorylation of the pore component, Cyclophilin D, and enable the subcellular repositioning of active mitochondria to membrane protrusions implicated in cell motility. An inhibitor of mitochondrial Hsp90s in preclinical development (gamitrinib) prevents adaptive mitochondrial reprogramming and shows potent antitumor activity in vitro and in vivo. Other therapeutic strategies to target mitochondria for cancer therapy include small-molecule inhibitors of mutant isocitrate dehydrogenase (IDH) IDH1 (AG-120) and IDH2 (AG-221), which opened new therapeutic prospects for patients with high-risk acute myelogenous leukemia (AML). A second approach of mitochondrial therapeutics focuses on agents that elevate toxic ROS levels from a leaky electron transport chain; nevertheless, the clinical experience with these compounds, including a quinone derivative, ARQ 501, and a copper chelator, elesclomol (STA-4783) is limited. In light of this evidence, we discuss how best to target a resurgence of mitochondrial bioenergetics for cancer therapy., (©2015 American Association for Cancer Research.)
- Published
- 2016
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22. Disabling mitochondrial reprogramming in cancer.
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Caino MC and Altieri DC
- Subjects
- Cell Adhesion drug effects, Cell Movement drug effects, Cytoskeleton drug effects, Cytoskeleton metabolism, Cytoskeleton pathology, Focal Adhesions drug effects, Focal Adhesions metabolism, Focal Adhesions pathology, Humans, Mitochondria metabolism, Mitochondria pathology, Neoplasms metabolism, Neoplasms pathology, Phosphatidylinositol 3-Kinases metabolism, Antineoplastic Agents therapeutic use, Mitochondria drug effects, Neoplasms drug therapy
- Abstract
Recent studies have demonstrated that tumor cells exposed to molecular therapy with PI3K antagonists redistribute their mitochondria to the peripheral cytoskeleton, fueling membrane dynamics, turnover of focal adhesion complexes and increased tumor cell motility and invasion. Although this process paradoxically increases metastatic propensity during molecular therapy, it also emphasizes a critical role of regional mitochondrial bioenergetics in tumor metabolic reprogramming and may offer prime therapeutic opportunities to prevent disseminated disease., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
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23. Survivin promotes oxidative phosphorylation, subcellular mitochondrial repositioning, and tumor cell invasion.
- Author
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Rivadeneira DB, Caino MC, Seo JH, Angelin A, Wallace DC, Languino LR, and Altieri DC
- Subjects
- Cell Movement, Female, Humans, Inhibitor of Apoptosis Proteins genetics, MCF-7 Cells, Male, Mitochondria genetics, Neoplasm Invasiveness, Neoplasm Proteins genetics, Neoplasms genetics, Neoplasms pathology, Survivin, Inhibitor of Apoptosis Proteins metabolism, Mitochondria metabolism, Neoplasm Proteins metabolism, Neoplasms metabolism, Oxidative Phosphorylation, Oxygen Consumption
- Abstract
Survivin promotes cell division and suppresses apoptosis in many human cancers, and increased abundance correlates with metastasis and poor prognosis. We showed that a pool of survivin that localized to the mitochondria of certain tumor cell lines enhanced the stability of oxidative phosphorylation complex II, which promoted cellular respiration. Survivin also supported the subcellular trafficking of mitochondria to the cortical cytoskeleton of tumor cells, which was associated with increased membrane ruffling, increased focal adhesion complex turnover, and increased tumor cell migration and invasion in cultured cells, and enhanced metastatic dissemination in vivo. Therefore, we found that mitochondrial respiration enhanced by survivin contributes to cancer metabolism, and relocalized mitochondria may provide a "regional" energy source to fuel tumor cell invasion and metastasis., (Copyright © 2015, American Association for the Advancement of Science.)
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- 2015
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24. PI3K therapy reprograms mitochondrial trafficking to fuel tumor cell invasion.
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Caino MC, Ghosh JC, Chae YC, Vaira V, Rivadeneira DB, Faversani A, Rampini P, Kossenkov AV, Aird KM, Zhang R, Webster MR, Weeraratna AT, Bosari S, Languino LR, and Altieri DC
- Subjects
- Biological Transport, Cell Line, Tumor, Cell Movement drug effects, Cytoskeleton metabolism, Energy Metabolism, Humans, Mitochondria metabolism, Proto-Oncogene Proteins c-akt metabolism, Signal Transduction, Enzyme Inhibitors pharmacology, Mitochondria drug effects, Neoplasm Invasiveness, Phosphoinositide-3 Kinase Inhibitors
- Abstract
Molecular therapies are hallmarks of "personalized" medicine, but how tumors adapt to these agents is not well-understood. Here we show that small-molecule inhibitors of phosphatidylinositol 3-kinase (PI3K) currently in the clinic induce global transcriptional reprogramming in tumors, with activation of growth factor receptors, (re)phosphorylation of Akt and mammalian target of rapamycin (mTOR), and increased tumor cell motility and invasion. This response involves redistribution of energetically active mitochondria to the cortical cytoskeleton, where they support membrane dynamics, turnover of focal adhesion complexes, and random cell motility. Blocking oxidative phosphorylation prevents adaptive mitochondrial trafficking, impairs membrane dynamics, and suppresses tumor cell invasion. Therefore, "spatiotemporal" mitochondrial respiration adaptively induced by PI3K therapy fuels tumor cell invasion, and may provide an important antimetastatic target.
- Published
- 2015
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25. Adaptive mitochondrial reprogramming and resistance to PI3K therapy.
- Author
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Ghosh JC, Siegelin MD, Vaira V, Faversani A, Tavecchio M, Chae YC, Lisanti S, Rampini P, Giroda M, Caino MC, Seo JH, Kossenkov AV, Michalek RD, Schultz DC, Bosari S, Languino LR, and Altieri DC
- Subjects
- Animals, Antineoplastic Agents therapeutic use, Apoptosis drug effects, Cell Line, Tumor, Cell Survival, Cyclophilins drug effects, Cyclophilins metabolism, Drug Synergism, Energy Metabolism drug effects, Guanidines therapeutic use, Humans, Immunocompromised Host, Mice, Phosphorylation drug effects, Protein Folding drug effects, Proto-Oncogene Proteins c-akt metabolism, Xenograft Model Antitumor Assays, Antineoplastic Agents pharmacology, Brain Neoplasms drug therapy, Brain Neoplasms metabolism, Cellular Reprogramming, Drug Resistance, Neoplasm, Elafin antagonists & inhibitors, Glioblastoma drug therapy, Glioblastoma metabolism, Guanidines pharmacology, Mitochondria drug effects
- Abstract
Background: Small molecule inhibitors of phosphatidylinositol-3 kinase (PI3K) have been developed as molecular therapy for cancer, but their efficacy in the clinic is modest, hampered by resistance mechanisms., Methods: We studied the effect of PI3K therapy in patient-derived tumor organotypic cultures (from five patient samples), three glioblastoma (GBM) tumor cell lines, and an intracranial model of glioblastoma in immunocompromised mice (n = 4-5 mice per group). Mechanisms of therapy-induced tumor reprogramming were investigated in a global metabolomics screening, analysis of mitochondrial bioenergetics and cell death, and modulation of protein phosphorylation. A high-throughput drug screening was used to identify novel preclinical combination therapies with PI3K inhibitors, and combination synergy experiments were performed. All statistical methods were two-sided., Results: PI3K therapy induces global metabolic reprogramming in tumors and promotes the recruitment of an active pool of the Ser/Thr kinase, Akt2 to mitochondria. In turn, mitochondrial Akt2 phosphorylates Ser31 in cyclophilin D (CypD), a regulator of organelle functions. Akt2-phosphorylated CypD supports mitochondrial bioenergetics and opposes tumor cell death, conferring resistance to PI3K therapy. The combination of a small-molecule antagonist of CypD protein folding currently in preclinical development, Gamitrinib, plus PI3K inhibitors (PI3Ki) reverses this adaptive response, produces synergistic anticancer activity by inducing mitochondrial apoptosis, and extends animal survival in a GBM model (vehicle: median survival = 28.5 days; Gamitrinib+PI3Ki: median survival = 40 days, P = .003), compared with single-agent treatment (PI3Ki: median survival = 32 days, P = .02; Gamitrinib: median survival = 35 days, P = .008 by two-sided unpaired t test)., Conclusions: Small-molecule PI3K antagonists promote drug resistance by repurposing mitochondrial functions in bioenergetics and cell survival. Novel combination therapies that target mitochondrial adaptation can dramatically improve on the efficacy of PI3K therapy in the clinic., (© The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)
- Published
- 2015
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26. Cancer cells exploit adaptive mitochondrial dynamics to increase tumor cell invasion.
- Author
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Caino MC and Altieri DC
- Subjects
- Animals, Antineoplastic Agents pharmacology, Antineoplastic Agents therapeutic use, Cell Line, Tumor, Enzyme Inhibitors pharmacology, Humans, Mitochondrial Dynamics drug effects, Neoplasm Invasiveness pathology, Neoplasm Invasiveness prevention & control, Neoplasms drug therapy, Neoplasms pathology, Phosphatidylinositol 3-Kinases metabolism, Phosphoinositide-3 Kinase Inhibitors, Proto-Oncogene Proteins c-akt antagonists & inhibitors, Proto-Oncogene Proteins c-akt metabolism, Mitochondrial Dynamics physiology, Neoplasms metabolism
- Abstract
Mitochondria are organelles that orchestrate a plethora of fundamental cellular functions that have been associated with various steps of tumor progression. However, we currently lack a mechanistic understanding of how mitochondrial dynamics, which reflects the organelles' exquisite heterogeneity in shape and spatial distribution, affects tumorigenesis. In a recent study, we uncovered a surprising new role of mitochondrial dynamics in response to PI3K therapy. We found that re-activation of Akt/mTOR signaling in tumor cells exposed to small molecule PI3K antagonists currently in the clinic triggered the transport of energetically active, elongated mitochondria to the cortical cytoskeleton of tumor cells. In turn, these repositioned mitochondria supported increased lamellipodia dynamics, faster turnover of focal adhesion complexes, heightened velocity and distance of random cell migration and increased tumor cell invasion. In this Extra View, we discuss the mechanistic basis of this paradoxical response to PI3K antagonists and propose possible strategies to disable mitochondrial adaptation.
- Published
- 2015
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27. Metabolic stress regulates cytoskeletal dynamics and metastasis of cancer cells.
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Caino MC, Chae YC, Vaira V, Ferrero S, Nosotti M, Martin NM, Weeraratna A, O'Connell M, Jernigan D, Fatatis A, Languino LR, Bosari S, and Altieri DC
- Subjects
- Adenylate Kinase metabolism, Animals, Antineoplastic Agents pharmacology, Autophagy-Related Protein-1 Homolog, Bone Neoplasms secondary, Carcinoma, Non-Small-Cell Lung mortality, Carcinoma, Non-Small-Cell Lung secondary, Cell Line, Tumor, Cell Movement, Female, Gene Knockdown Techniques, Guanidines pharmacology, HSP90 Heat-Shock Proteins genetics, HSP90 Heat-Shock Proteins metabolism, Hexokinase metabolism, Humans, Intracellular Signaling Peptides and Proteins genetics, Intracellular Signaling Peptides and Proteins metabolism, Kaplan-Meier Estimate, Lactams, Macrocyclic pharmacology, Liver Neoplasms, Experimental secondary, Lung Neoplasms mortality, Lung Neoplasms pathology, Mice, Mice, SCID, Mitochondria metabolism, Mitochondrial Membranes enzymology, NIH 3T3 Cells, Neoplasm Transplantation, Phosphorylation, Protein Processing, Post-Translational, Protein Serine-Threonine Kinases genetics, Protein Serine-Threonine Kinases metabolism, RNA, Small Interfering genetics, Bone Neoplasms metabolism, Carcinoma, Non-Small-Cell Lung metabolism, Cytoskeleton metabolism, Liver Neoplasms, Experimental metabolism, Lung Neoplasms metabolism, Stress, Physiological
- Abstract
Metabolic reprogramming is an important driver of tumor progression; however, the metabolic regulators of tumor cell motility and metastasis are not understood. Here, we show that tumors maintain energy production under nutrient deprivation through the function of HSP90 chaperones compartmentalized in mitochondria. Using cancer cell lines, we found that mitochondrial HSP90 proteins, including tumor necrosis factor receptor-associated protein-1 (TRAP-1), dampen the activation of the nutrient-sensing AMPK and its substrate UNC-51-like kinase (ULK1), preserve cytoskeletal dynamics, and release the cell motility effector focal adhesion kinase (FAK) from inhibition by the autophagy initiator FIP200. In turn, this results in enhanced tumor cell invasion in low nutrients and metastatic dissemination to bone or liver in disease models in mice. Moreover, we found that phosphorylated ULK1 levels were correlated with shortened overall survival in patients with non-small cell lung cancer. These results demonstrate that mitochondrial HSP90 chaperones, including TRAP-1, overcome metabolic stress and promote tumor cell metastasis by limiting the activation of the nutrient sensor AMPK and preventing autophagy.
- Published
- 2013
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28. Regulation of Transcriptional Networks by PKC Isozymes: Identification of c-Rel as a Key Transcription Factor for PKC-Regulated Genes.
- Author
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Garg R, Caino MC, and Kazanietz MG
- Subjects
- Apoptosis, Humans, Isoenzymes, Male, Prostatic Neoplasms enzymology, Proto-Oncogene Proteins c-rel genetics, Transcriptional Activation, Tumor Cells, Cultured, Gene Expression Regulation, Neoplastic, Gene Regulatory Networks, Promoter Regions, Genetic, Prostatic Neoplasms genetics, Protein Kinase C genetics, Proto-Oncogene Proteins c-rel metabolism, Regulatory Elements, Transcriptional
- Abstract
Background: Activation of protein kinase C (PKC), a family of serine-threonine kinases widely implicated in cancer progression, has major impact on gene expression. In a recent genome-wide analysis of prostate cancer cells we identified distinctive gene expression profiles controlled by individual PKC isozymes and highlighted a prominent role for PKCδ in transcriptional activation., Principal Findings: Here we carried out a thorough bioinformatics analysis to dissect transcriptional networks controlled by PKCα, PKCδ, and PKCε, the main diacylglycerol/phorbol ester PKCs expressed in prostate cancer cells. Despite the remarkable differences in the patterns of transcriptional responsive elements (REs) regulated by each PKC, we found that c-Rel represents the most frequent RE in promoters regulated by all three PKCs. In addition, promoters of PKCδ-regulated genes were particularly enriched with REs for CREB, NF-E2, RREB, SRF, Oct-1, Evi-1, and NF-κB. Most notably, by using transcription factor-specific RNAi we were able to identify subsets of PKCδ-regulated genes modulated by c-Rel and CREB. Furthermore, PKCδ-regulated genes condensed under the c-Rel transcriptional regulation display significant functional interconnections with biological processes such as angiogenesis, inflammatory response, and cell motility., Conclusion/significance: Our study identified candidate transcription factors in the promoters of PKC regulated genes, in particular c-Rel was found as a key transcription factor in the control of PKCδ-regulated genes. The deconvolution of PKC-regulated transcriptional networks and their nodes may greatly help in the identification of PKC effectors and have significant therapeutics implications.
- Published
- 2013
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29. Control of tumor bioenergetics and survival stress signaling by mitochondrial HSP90s.
- Author
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Chae YC, Caino MC, Lisanti S, Ghosh JC, Dohi T, Danial NN, Villanueva J, Ferrero S, Vaira V, Santambrogio L, Bosari S, Languino LR, Herlyn M, and Altieri DC
- Subjects
- AMP-Activated Protein Kinase Kinases, AMP-Activated Protein Kinases genetics, AMP-Activated Protein Kinases metabolism, Animals, Autophagy, Cell Line, Tumor, Cell Proliferation, Cell Survival, Cytosol metabolism, Endoplasmic Reticulum metabolism, Endoplasmic Reticulum Chaperone BiP, Guanidines pharmacology, Heat-Shock Proteins genetics, Humans, Kinesins genetics, Lactams, Macrocyclic pharmacology, Lung Neoplasms, Mechanistic Target of Rapamycin Complex 1, Mice, Multiprotein Complexes, Neoplasms pathology, Phosphorylation, Protein Folding, Protein Serine-Threonine Kinases genetics, Proteins antagonists & inhibitors, RNA Interference, RNA, Small Interfering, Signal Transduction, TOR Serine-Threonine Kinases, Energy Metabolism, HSP90 Heat-Shock Proteins metabolism, Mitochondria metabolism, Neoplasms metabolism, Unfolded Protein Response
- Abstract
Tumors successfully adapt to constantly changing intra- and extracellular environments, but the wirings of this process are still largely elusive. Here, we show that heat-shock-protein-90-directed protein folding in mitochondria, but not cytosol, maintains energy production in tumor cells. Interference with this process activates a signaling network that involves phosphorylation of nutrient-sensing AMP-activated kinase, inhibition of rapamycin-sensitive mTOR complex 1, induction of autophagy, and expression of an endoplasmic reticulum unfolded protein response. This signaling network confers a survival and proliferative advantage to genetically disparate tumors, and correlates with worse outcome in lung cancer patients. Therefore, mitochondrial heat shock protein 90s are adaptive regulators of tumor bioenergetics and tractable targets for cancer therapy., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2012
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30. Proteins kinase Cɛ is required for non-small cell lung carcinoma growth and regulates the expression of apoptotic genes.
- Author
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Caino MC, Lopez-Haber C, Kim J, Mochly-Rosen D, and Kazanietz MG
- Subjects
- Animals, Apoptosis drug effects, Carcinoma, Non-Small-Cell Lung pathology, Cell Proliferation drug effects, Cell Survival, Genes, bcl-2, Humans, Lung Neoplasms pathology, Mice, Mice, Nude, Neoplasm Transplantation, Peptide Fragments pharmacology, Protein Kinase C-epsilon antagonists & inhibitors, Protein Kinase C-epsilon genetics, Protein Kinase Inhibitors pharmacology, RNA Interference, RNA, Small Interfering, Receptors, Tumor Necrosis Factor metabolism, Carcinoma, Non-Small-Cell Lung enzymology, Lung Neoplasms enzymology, Protein Kinase C-epsilon metabolism
- Abstract
Protein kinase C (PKC)ɛ, a member of the novel PKC family, has key roles in mitogenesis and survival in normal and cancer cells. PKCɛ is frequently overexpressed in epithelial cancers, particularly in lung cancer. Using a short-hairpin RNA approach, here we established that PKCɛ is required for non-small cell lung carcinoma (NSCLC) growth in vitro as well as tumor growth when inoculated into athymic mice. Moreover, sustained delivery of a PKCɛ-selective inhibitor peptide, ɛV1-2, reduced xenograft growth in mice. Both RNA interference depletion and pharmacological inhibition of PKCɛ caused a marked elevation in the number of apoptotic cells in NSCLC tumors. PKCɛ-depleted NSCLC cells show elevated expression of pro-apoptotic proteins of the Bcl-2 family, caspase recruitment domain-containing proteins and tumor necrosis factor ligands/receptor superfamily members. Moreover, a Gene Set Enrichment Analysis revealed that a vast majority of the genes changed in PKCɛ-depleted cells were also deregulated in human NSCLC. Our results strongly suggest that PKCɛ is required for NSCLC cell survival and maintenance of NSCLC tumor growth. Therefore, PKCɛ may represent an attractive therapeutic target for NSCLC.
- Published
- 2012
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31. Non-small cell lung carcinoma cell motility, rac activation and metastatic dissemination are mediated by protein kinase C epsilon.
- Author
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Caino MC, Lopez-Haber C, Kissil JL, and Kazanietz MG
- Subjects
- Animals, Cell Line, Tumor, Cell Movement, Disease Progression, Enzyme Activation, Extracellular Matrix metabolism, Gene Expression Regulation, Neoplastic, Guanosine Triphosphate metabolism, Humans, Male, Mice, Mice, Nude, Neoplasm Metastasis, RNA Interference, Signal Transduction, Carcinoma metabolism, Carcinoma pathology, Carcinoma, Non-Small-Cell Lung metabolism, Carcinoma, Non-Small-Cell Lung pathology, Lung Neoplasms metabolism, Lung Neoplasms pathology, Protein Kinase C-epsilon metabolism, rac GTP-Binding Proteins metabolism
- Abstract
Background: Protein kinase C (PKC) ε, a key signaling transducer implicated in mitogenesis, survival, and cancer progression, is overexpressed in human primary non-small cell lung cancer (NSCLC). The role of PKCε in lung cancer metastasis has not yet been established., Principal Findings: Here we show that RNAi-mediated knockdown of PKCε in H358, H1299, H322, and A549 NSCLC impairs activation of the small GTPase Rac1 in response to phorbol 12-myristate 13-acetate (PMA), serum, or epidermal growth factor (EGF). PKCε depletion markedly impaired the ability of NSCLC cells to form membrane ruffles and migrate. Similar results were observed by pharmacological inhibition of PKCε with εV1-2, a specific PKCε inhibitor. PKCε was also required for invasiveness of NSCLC cells and modulated the secretion of extracellular matrix proteases and protease inhibitors. Finally, we found that PKCε-depleted NSCLC cells fail to disseminate to lungs in a mouse model of metastasis., Conclusions: Our results implicate PKCε as a key mediator of Rac signaling and motility of lung cancer cells, highlighting its potential as a therapeutic target.
- Published
- 2012
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32. Differential regulation of gene expression by protein kinase C isozymes as determined by genome-wide expression analysis.
- Author
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Caino MC, von Burstin VA, Lopez-Haber C, and Kazanietz MG
- Subjects
- Antineoplastic Agents, Phytogenic pharmacology, Carcinogens pharmacology, Cell Line, Etoposide pharmacology, Gene Expression Profiling methods, Gene Expression Regulation drug effects, Humans, Isoenzymes genetics, Isoenzymes metabolism, Oligonucleotide Array Sequence Analysis methods, Phorbol Esters pharmacology, Protein Kinase C genetics, Transcription, Genetic drug effects, Gene Expression Regulation physiology, Genome-Wide Association Study, Protein Kinase C metabolism, Transcription, Genetic physiology
- Abstract
Protein kinase C (PKC) isozymes are key signal transducers involved in normal physiology and disease and have been widely implicated in cancer progression. Despite our extensive knowledge of the signaling pathways regulated by PKC isozymes and their effectors, there is essentially no information on how individual members of the PKC family regulate gene transcription. Here, we report the first PKC isozyme-specific analysis of global gene expression by microarray using RNAi depletion of diacylglycerol/phorbol ester-regulated PKCs. A thorough analysis of this microarray data revealed unique patterns of gene expression controlled by PKCα, PKCδ, and PKCε, which are remarkably different in cells growing in serum or in response to phorbol ester stimulation. PKCδ is the most relevant isoform in controlling the induction of genes by phorbol ester stimulation, whereas PKCε predominantly regulates gene expression in serum. We also established that two PKCδ-regulated genes, FOSL1 and BCL2A1, mediate the apoptotic effect of phorbol esters or the chemotherapeutic agent etoposide in prostate cancer cells. Our studies offer a unique opportunity for establishing novel transcriptional effectors for PKC isozymes and may have significant functional and therapeutic implications.
- Published
- 2011
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33. Rift valley fever virus infection of human cells and insect hosts is promoted by protein kinase C epsilon.
- Author
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Filone CM, Hanna SL, Caino MC, Bambina S, Doms RW, and Cherry S
- Subjects
- Acetophenones pharmacology, Animals, Benzophenanthridines pharmacology, Benzopyrans pharmacology, Cell Line, Chlorocebus aethiops, Diptera genetics, Diptera metabolism, Diptera virology, Drug Evaluation, Preclinical, Enzyme Inhibitors pharmacology, Fluorescent Antibody Technique, HEK293 Cells, Humans, Immunoblotting, Insecta cytology, Insecta metabolism, Protein Kinase C-epsilon antagonists & inhibitors, Protein Kinase C-epsilon genetics, RNA Interference, Rift Valley fever virus drug effects, Vero Cells, Insecta virology, Protein Kinase C-epsilon metabolism, Rift Valley fever virus physiology
- Abstract
As an arthropod-borne human pathogen, Rift Valley fever virus (RVFV) cycles between an insect vector and mammalian hosts. Little is known about the cellular requirements for infection in either host. Here we developed a tissue culture model for RVFV infection of human and insect cells that is amenable to high-throughput screening. Using this approach we screened a library of 1280 small molecules with pharmacologically defined activities and identified 59 drugs that inhibited RVFV infection with 15 inhibiting RVFV replication in both human and insect cells. Amongst the 15 inhibitors that blocked infection in both hosts was a subset that inhibits protein kinase C. Further studies found that infection is dependent upon the novel protein kinase C isozyme epsilon (PKCε) in both human and insect cells as well as in adult flies. Altogether, these data show that inhibition of cellular factors required for early steps in the infection cycle including PKCε can block RVFV infection, and may represent a starting point for the development of anti-RVFV therapeutics.
- Published
- 2010
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34. Regulation of prostate cancer cell survival by protein kinase Cepsilon involves bad phosphorylation and modulation of the TNFalpha/JNK pathway.
- Author
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Meshki J, Caino MC, von Burstin VA, Griner E, and Kazanietz MG
- Subjects
- Apoptosis, Cell Line, Tumor, Cell Survival, Humans, Male, Phosphorylation, Signal Transduction, Tetradecanoylphorbol Acetate pharmacology, bcl-Associated Death Protein, JNK Mitogen-Activated Protein Kinases metabolism, Prostatic Neoplasms metabolism, Prostatic Neoplasms pathology, Protein Kinase C-epsilon metabolism, Tumor Necrosis Factor-alpha metabolism
- Abstract
Protein kinase Cepsilon (PKCepsilon), a diacyglycerol- and phorbol ester-responsive serine-threonine kinase, has been implicated in mitogenic and survival control, and it is markedly overexpressed in human tumors, including in prostate cancer. Although prostate cancer cells undergo apoptosis in response to phorbol ester stimulation via PKCdelta-mediated release of death factors, the involvement of PKCepsilon in this response is not known. PKCepsilon depletion by RNAi or expression of a dominant negative kinase-dead PKCepsilon mutant potentiated the apoptotic response of PMA and sensitized LNCaP cells to the death receptor ligand TNFalpha. On the other hand, overexpression of PKCepsilon by adenoviral means protected LNCaP cells against apoptotic stimuli. Interestingly, PKCepsilon RNAi depletion significantly enhanced the release of TNFalpha in response to PMA and greatly potentiated JNK activation by this cytokine. Further mechanistic analysis revealed that PMA fails to promote phosphorylation of Bad in Ser(112) in PKCepsilon-depleted LNCaP cells, whereas PKCepsilon overexpression greatly enhanced Bad phosphorylation. This effect was independent of Akt, ERK, or p90Rsk, well established kinases for Ser(112) in Bad. Moreover, expression of a S112A-Bad mutant potentiated PMA-induced apoptosis. Finally, we found that upon activation PKCepsilon accumulated in mitochondrial fractions in LNCaP cells and that Bad was a substrate of PKCepsilon in vitro. Our results established that PKCepsilon modulates survival in prostate cancer cells via multiple pathways.
- Published
- 2010
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35. A novel cross-talk in diacylglycerol signaling: the Rac-GAP beta2-chimaerin is negatively regulated by protein kinase Cdelta-mediated phosphorylation.
- Author
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Griner EM, Caino MC, Sosa MS, Colón-González F, Chalmers MJ, Mischak H, and Kazanietz MG
- Subjects
- Animals, COS Cells, Chlorocebus aethiops, Cytosol metabolism, Diglycerides chemistry, HeLa Cells, Humans, Mice, Mutation, Neurons metabolism, Phorbol Esters chemistry, Phosphorylation, Protein Kinase C metabolism, Protein-Tyrosine Kinases chemistry, Signal Transduction, Diglycerides metabolism, GTPase-Activating Proteins metabolism, Neoplasm Proteins chemistry, Protein Kinase C-delta metabolism, rac GTP-Binding Proteins metabolism
- Abstract
Although the family of chimaerin Rac-GAPs has recently gained significant attention for their involvement in development, cancer, and neuritogenesis, little is known about their molecular regulation. Chimaerins are activated by the lipid second messenger diacylglycerol via their C1 domain upon activation of tyrosine kinase receptors, thereby restricting the magnitude of Rac signaling in a receptor-regulated manner. Here we identified a novel regulatory mechanism for beta2-chimaerin via phosphorylation. Epidermal growth factor or the phorbol ester phorbol 12-myristate 13-acetate caused rapid phosphorylation of beta2-chimaerin on Ser(169) located in the SH2-C1 domain linker region via protein kinase Cdelta, which retained beta2-chimaerin in the cytosol and prevented its C1 domain-mediated translocation to membranes. Furthermore, despite the fact that Ser(169) phosphorylation did not alter intrinsic Rac-GAP activity in vitro, a non-phosphorylatable beta2-chimaerin mutant was highly sensitive to translocation, and displayed enhanced association with activated Rac, enhanced Rac-GAP activity, and anti-migratory properties when expressed in cells. Our results not only revealed a novel regulatory mechanism that facilitates Rac activation, but also identified a novel mechanism of cross-talk between diacylglycerol receptors that restricts beta2-chimaerin relocalization and activation.
- Published
- 2010
- Full Text
- View/download PDF
36. [Defense pact on health: disclosing the users' rights through action research].
- Author
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Koerich MS, Backes DS, Marchiori MC, and Erdmann AL
- Subjects
- Health Personnel standards, Health Services statistics & numerical data, Humans, Nursing Research, Patient Rights
- Abstract
We objective to discuss the Users' Rights Booklet of the Health Unified System with patients and family members who had looked for attendance in public hospital service. One has chosen the action research, a qualitative and constructive method, which takes into account collective participation and planned action for changes of situations. The data were collected along with the research participants' discussions by means of weekly meetings throughout 2007. The codified speeches were analyzed and resulted in three themes: rights and duties of healthcare users; qualification of health professionals; receptivity to healthcare users. The users' rights booklet consists of an important means for citizens to know their rights of access to the healthcare system, allowing them to contribute in a critical and co-responsible way to discussions and actions in favor of a better healthcare system.
- Published
- 2009
- Full Text
- View/download PDF
37. Hallmarks for senescence in carcinogenesis: novel signaling players.
- Author
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Caino MC, Meshki J, and Kazanietz MG
- Subjects
- Apoptosis, Models, Biological, Aging genetics, Cell Transformation, Neoplastic genetics, Cellular Senescence physiology, Neoplasms genetics, Signal Transduction genetics
- Abstract
Cellular senescence is a potent anti-cancer mechanism controlled by tumor suppressor genes, particularly p53 and pRb, which is characterized by the irreversible loss of proliferation. Senescence induced by DNA damage, oncogenic stimulation, or excessive mitogenic input, serves as a barrier that counteracts cancer progression. Emerging evidence in cellular and in in vivo models revealed the involvement of additional signaling players in senescence, including PML, CK2, Bcl-2, PI3K effectors such as Rheb, Rho small GTPases, and cytokines. Recent studies have also implicated protein kinase C (PKC) isozymes as modulators of senescence phenotypes and showed that phorbol esters, widely used PKC activators, can induce senescence in a number of cancer cells. These novel findings suggest a complex array of cross-talks between senescence pathways and may have significant implications in cancer therapy.
- Published
- 2009
- Full Text
- View/download PDF
38. S-Phase-specific activation of PKC alpha induces senescence in non-small cell lung cancer cells.
- Author
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Oliva JL, Caino MC, Senderowicz AM, and Kazanietz MG
- Subjects
- Carcinogens pharmacology, Carcinoma, Non-Small-Cell Lung genetics, Carcinoma, Non-Small-Cell Lung pathology, Cell Cycle drug effects, Cell Line, Tumor, Cyclin-Dependent Kinase Inhibitor p21 genetics, Enzyme Activation drug effects, Enzyme Activation genetics, Gene Expression Regulation, Neoplastic drug effects, Gene Expression Regulation, Neoplastic genetics, Humans, Isoenzymes genetics, Isoenzymes metabolism, Protein Kinase C-alpha genetics, Protein Kinase C-delta genetics, Telomerase genetics, Telomerase metabolism, Tetradecanoylphorbol Acetate pharmacology, Up-Regulation drug effects, Up-Regulation genetics, beta-Galactosidase genetics, beta-Galactosidase metabolism, Carcinoma, Non-Small-Cell Lung enzymology, Cellular Senescence drug effects, Cellular Senescence genetics, Cyclin-Dependent Kinase Inhibitor p21 biosynthesis, Protein Kinase C-alpha metabolism, Protein Kinase C-delta metabolism, S Phase drug effects, S Phase genetics
- Abstract
Protein kinase C (PKC) has been widely implicated in positive and negative control of cell proliferation. We have recently shown that treatment of non-small cell lung cancer (NSCLC) cells with phorbol 12-myristate 13-acetate (PMA) during G1 phase inhibits the progression into S phase, an effect mediated by PKC delta-induced up-regulation of the cell cycle inhibitor p21 Cip1. However, PMA treatment in asynchronously growing NSCLC cells leads to accumulation of cells in G2/M. Studies in post-G1 phases revealed that PMA induced an irreversible G2/M cell cycle arrest in NSCLC cells and conferred morphological and biochemical features of senescence, including elevated SA-beta-Gal activity and reduced telomerase activity. Remarkably, this effect was phase-specific, as it occurred only when PKC was activated in S, but not in G1, phase. Mechanistic analysis revealed a crucial role for the classical PKC alpha isozyme as mediator of the G2/M arrest and senescence, as well as for inducing p21(Cip1) an obligatory event for conferring the senescence phenotype. In addition to the unappreciated role of PKC isozymes, and specifically PKC alpha, in senescence, our data introduce the paradigm that discrete PKCs trigger distinctive responses when activated in different phases of the cell cycle via a common mechanism that involves p21 Cip1 up-regulation.
- Published
- 2008
- Full Text
- View/download PDF
39. Phorbol ester-induced apoptosis and senescence in cancer cell models.
- Author
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Xiao L, Caino MC, von Burstin VA, Oliva JL, and Kazanietz MG
- Subjects
- Adenoviridae enzymology, Apoptosis drug effects, Cell Cycle physiology, Cell Line, Tumor, Cellular Senescence drug effects, Cellular Senescence physiology, Humans, Male, Prostatic Neoplasms, Protein Kinase C-alpha physiology, Protein Kinase C-epsilon physiology, RNA Interference, Apoptosis physiology, Protein Kinase C-delta physiology, Tetradecanoylphorbol Acetate pharmacology
- Abstract
Protein kinase C (PKC) isozymes catalyze the phosphorylation of substrates that play key roles in the control in proliferation, differentiation, and survival. Treatment of cells with phorbol esters, activators of classical and novel PKC isozymes, leads to a plethora of responses in a strict cell-type-dependent specific manner. Interestingly, a few cell models undergo apoptosis in response to phorbol ester stimulation, including androgen-dependent prostate cancer cells. This effect involves the autocrine secretion of death factors and activation of the extrinsic apoptotic cascade. We have recently found that in other models, such as lung cancer cells, phorbol esters lead to irreversible growth arrest and senescence. This chapter describes the methods we use to assess these phorbol ester responses in cancer cell models, focusing on apoptosis and senescence.
- Published
- 2008
- Full Text
- View/download PDF
40. Benzo[a]pyrene-7,8-dihydrodiol promotes checkpoint activation and G2/M arrest in human bronchoalveolar carcinoma H358 cells.
- Author
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Caino MC, Oliva JL, Jiang H, Penning TM, and Kazanietz MG
- Subjects
- Cell Line, Tumor, Cell Proliferation drug effects, Checkpoint Kinase 1, Cytochrome P-450 Enzyme System physiology, DNA Damage, Dihydroxydihydrobenzopyrenes metabolism, Enzyme Activation, Humans, Adenocarcinoma, Bronchiolo-Alveolar pathology, Cell Division drug effects, Dihydroxydihydrobenzopyrenes pharmacology, G2 Phase drug effects, Lung Neoplasms pathology, Protein Kinases physiology
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) are potent carcinogens that require metabolic activation inside cells. The proximate carcinogens PAH-diols can be converted to o-quinones by aldo-keto reductases (AKRs) or to diol-epoxides by cytochrome P450 (P450) enzymes. We assessed the effect of benzo[a]pyrene-7,8-dihydrodiol (BPD) on proliferation in p53-null bronchoalveolar carcinoma H358 cells. BPD treatment led to a significant inhibition of proliferation and arrest in G2/M in H358 cells. The relative contribution of the AKR and P450 pathways to cell cycle arrest was assessed. Overexpression of AKR1A1 did not affect cell proliferation or cell cycle progression, and benzo[a]pyrene-7,8-dione did not cause any noticeable effect on cell growth, suggesting that AKR1A1 metabolic products were not involved in the antiproliferative effect of BPD. On the other hand, blockade of P450 induction or inhibition of P450 activity greatly impaired the effect of BPD. Moreover, P450 induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin significantly enhanced the antiproliferative effect of BPD. Mechanistic studies revealed that BPD caused a DNA damage response, Chk1 activation, and accumulation of phospho-Cdc2 (Tyr15) in H358 cells, effects that were impaired by an ataxia-telangectasia mutated (ATM)/ATM-related (ATR) inhibitor. Similar results were observed in human bronchoepithelial BEAS-2B cells, arguing for analogous mechanisms in tumorigenic and immortalized nontumorigenic cells lacking functional p53. Our data suggest that a p53-independent pathway operates in lung epithelial cells in response to BPD that involves P450 induction and subsequent activation of the ATR/ATM/Chk1 damage check-point pathway and cell cycle arrest in G2/M.
- Published
- 2007
- Full Text
- View/download PDF
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