Search

Glioblastoma multiforme (GBM) has high mortality and recurrence rates. Malignancy resilience is ascribed to Glioblastoma Stem Cells (GSCs), which are resistant to Temozolomide (TMZ), the gold standard for GBM post-surgical treatment. However, Nitric Oxide (NO) has demonstrated anti-cancer efficacy in GBM cells, but its potential impact on GSCs remains unexplored. Accordingly, we investigated the effects of NO, both alone and in combination with TMZ, on patient-derived GSCs. Experimentally selected concentrations of diethylenetriamine/NO adduct and TMZ were used through a time course up to 21 days of treatment, to evaluate GSC proliferation and death, functional recovery, and apoptosis. Immunofluorescence and Western blot analyses revealed treatment-induced effects in cell cycle and DNA damage occurrence and repair. Our results showed that NO impairs self-renewal, disrupts cell-cycle progression, and expands the quiescent cells' population. Consistently, NO triggered a significant but tolerated level of DNA damage, but not apoptosis. Interestingly, NO/TMZ cotreatment further inhibited cell cycle progression, augmented G0 cells, induced cell death, but also enhanced DNA damage repair activity. These findings suggest that, although NO administration does not eliminate GSCs, it stunts their proliferation, and makes cells susceptible to TMZ. The resulting cytostatic effect may potentially allow long-term control over the GSCs' subpopulation. [ABSTRACT FROM AUTHOR]

While platinum-based compounds such as cisplatin form the backbone of chemotherapy, the use of these compounds is limited by resistance and toxicity, driving the development of novel complexes with cytostatic properties. In this study, we synthesized a set of half-sandwich complexes of platinum-group metal ions (Ru(II), Os(II), Ir(III) and Rh(III)) with an N,N-bidentate ligand comprising a C-glucosaminyl group and a heterocycle, such as pyridine, pyridazine, pyrimidine, pyrazine or quinoline. The sugar-containing ligands themselves are unknown compounds and were obtained by nucleophilic additions of lithiated heterocycles to O-perbenzylated 2-nitro-glucal. Reduction of the adducts and, where necessary, subsequent protecting group manipulations furnished the above C-glucosaminyl heterocycles in their O-perbenzylated, O-perbenzoylated and O-unprotected forms. The derived complexes were tested on A2780 ovarian cancer cells. Pyridine, pyrazine and pyridazine-containing complexes proved to be cytostatic and cytotoxic on A2780 cells, while pyrimidine and quinoline derivatives were inactive. The best complexes contained pyridine as the heterocycle. The metal ion with polyhapto arene/arenyl moiety also impacted on the biological activity of the complexes. Ruthenium complexes with p-cymene and iridium complexes with Cp* had the best performance in ovarian cancer cells, followed by osmium complexes with p-cymene and rhodium complexes with Cp*. Finally, the chemical nature of the protective groups on the hydroxyl groups of the carbohydrate moiety were also key determinants of bioactivity; in particular, O-benzyl groups were superior to O-benzoyl groups. The IC50 values of the complexes were in the low micromolar range, and, importantly, the complexes were less active against primary, untransformed human dermal fibroblasts; however, the anticipated therapeutic window is narrow. The bioactive complexes exerted cytostasis on a set of carcinomas such as cell models of glioblastoma, as well as breast and pancreatic cancers. Furthermore, the same complexes exhibited bacteriostatic properties against multiresistant Gram-positive Staphylococcus aureus and Enterococcus clinical isolates in the low micromolar range. [ABSTRACT FROM AUTHOR]

Cripowellins from Crinum erubescens are known pesticidal and have potent antiplasmodial activity. To gain mechanistic insights to this class of natural products, studies to determine the timing of action of cripowellins within the asexual intraerythrocytic cycle of Plasmodium falciparum were performed and led to the observation that this class of natural products induced reversible cytostasis in the ring stage within the first 24 h of treatment. The transcriptional program necessary for P. falciparum to progress through the asexual intraerythrocytic life cycle is well characterized. Whole transcriptome abundance analysis showed that cripowellin B "pauses" the transcriptional program necessary to progress through the intraerythrocytic life cycle coinciding with the lack of morphological progression of drug treated parasites. In addition, cripowellin B-treated parasites re-enter transcriptional progression after treatment was removed. This study highlights the use of cripowellins as chemical probes to reveal new aspects of cell cycle progression of the asexual ring stage of P. falciparum which could be leveraged for the generation of future antimalarial therapeutics. [ABSTRACT FROM AUTHOR]

Polyelectrolytes assembled layer-by-layer (PEMs) are commonly used as functional coatings to build-up biological interfaces, particularly suitable as compatible layers for the interaction with a biological medium, providing suitable conditions to promote or prevent cell seeding while maintaining the phenotype. The proper assessment of the biocompatibility of PEMs and the elucidation of the related mechanisms are therefore of paramount importance. In this study, we report in detail the effect of two different PEM endings, polystyrene sulfonate (PSS) and polyethylenimine (PEI), respectively, on the cell adhesion, growth, and viability of human bone mesenchymal stromal cells (MSCs). The results have shown that PSS-ended substrates appear to be the most suitable to drive the cell adhesion and phenotype maintenance of MSCs, showing good biocompatibility. On the contrary, while the cells seem to adhere more quickly and strongly on the PEI-ended surfaces, the interaction with PEI significantly affects the growth and viability, reducing the cell spreading capability, by sequestering the adhesion molecules already in the very early steps of cell–substrate contact. These results point to the promotion of a cytostatic effect of PEI, rather than the often-claimed cytotoxicity. [ABSTRACT FROM AUTHOR]

Purpose: Urinary bladder urothelial carcinoma (UBUC) is a common malignant disease, and its high recurrence rates impose a heavy clinical burden. The objective of this study was to identify signaling pathways downstream of epithelial membrane protein 2 (EMP2), which induces cytostasis and apoptosis in UBUC. Methods: A series of in vitro and in vivo assays using different UBUC-derived cell lines and mouse xenograft models were performed, respectively. In addition, primary UBUC specimens were evaluated by immunohistochemistry. Results: Exogenous expression of EMP2 in J82 UBUC cells significantly decreased DNA replication and altered the expression levels of several TGFβ signaling-related proteins. EMP2 knockdown in BFTC905 UBUC cells resulted in opposite effects. EMP2-dysregulated cell cycle progression was found to be mediated by the TGFβ/TGFBR1/SP1 family member SMAD. EMP2 or purinergic receptor P2X7 (P2RX7) gene expression upregulation induced apoptosis via both intrinsic and extrinsic pathways. In 242 UBUC patient samples, P2RX7 protein levels were found to be significantly and positively correlated with EMP2 protein levels. Low P2RX7 levels conferred poor disease-specific and metastasis-free survival rates, and significantly decreased apoptotic cell rates. EMP2 was found to physically interact with P2RX7. In the presence of a P2RX7 agonist, BzATP, overexpression of both EMP2 and P2RX7 significantly increased apoptotic cell rates compared to overexpression of EMP2 or P2RX7 alone. Conclusions: EMP2 induces cytostasis via the TGFβ/SMAD/SP1 axis and recruits P2RX7 to enhance apoptosis in UBUC. Our data provide new insights that may be employed for the design of UBUC targeting therapies. [ABSTRACT FROM AUTHOR]

Aims Zoledronic acid (ZA), a FDA approved drug has used widely in the treatment of bone metastasis complications, has been linked to renal toxicity with unclear mechanism. The present study is aimed at investigating the genotoxic and cytotoxic effects of ZA in renal epithelial cells. Main methods The genotoxic effect of ZA in Vero and MDCK cells determined by cytokinesis block micronucleus (CBMN) assay. The cytotoxic effect assessed by analysing cell cycle profile, cell death and mitochondrial membrane potential by flow cytometry using propidium iodide, AnnexinV-FITC/PI and JC1 dye staining, respectively, BAX and Bcl-2 expression by Western blotting and caspase activity by spectrofluorimetry. Key findings The cytotoxic effect of ZA based on MTT assay revealed variable sensitivities of Vero and MDCK cells, with IC 50 values of 7.41 and 109.58 μM, respectively. The CBMN assay has shown prominent dose-dependent (IC 10-50 ) induction of micronuclei formation in both cells, indicating ZA's clastogenic and aneugenic potential. Further, the ZA treatment led the cells to apoptosis, evident from dose-dependent increase in the percentage of cells in subG1 phase and display of membranous phosphatidylserine translocation. Studies also confirmed apoptosis through mitochondria, evident from the prominent increase in BAX/Bcl-2 ratio, mitochondrial membrane depolarization and caspase-3/7 activity. In addition, ZA reduces cytokinetic activity of renal cells, evident from dose-wise lowered replicative indices. Significance The study depict ZA's potential genotoxic effect along with cytotoxic effect in renal epithelial cells, could be key factors for the development of renal complications associated with it, which prompts renal safety measures in lieu with ZA usage. [ABSTRACT FROM AUTHOR]

Purpose: Triple-negative breast cancers (TNBC) lack expression of three common cell surface receptors, i.e., estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2). Accordingly, TNBCs are associated with fewer treatment options and a relatively poor prognosis. Having screened a National Cancer Institute natural compound library, the purpose of this study was to investigate the bioactivity of compound C4 (Crassin) in TNBC cells. Methods: Cell viability assays were performed in two TNBC cell lines, MDA-MB-231 and 4T1, following C4 treatment in the presence or absence of the antioxidant N-acetyl-L-cysteine (NAC). Phosphorylation of Akt and ERK was assessed by Western blotting. Apoptosis, necrosis, autophagy, necroptosis, ferroptosis and cytostasis assays were performed to explain viability deficits resulting from C4 exposure. Results: We found that the viability of the TNBC cells tested decreased in a concentration- and time-dependent fashion following C4 treatment. This decrease coincided with an unexpected increase in the expression of the cell survival effectors pAkt and pERK. In addition, we found that both the decreased cell viability and the increased pAkt/pERK levels could be rescued by the antioxidant NAC, suggesting a central role for reactive oxygen species (ROS) in the mechanism of action of C4. Necrosis, apoptosis, necroptosis and ferroptosis could be ruled out as cell death mechanisms. Instead, we found that C4 induced cytostasis downstream of ROS activation. Finally, we observed a synergistic effect between C4 and the chemotherapeutic drug doxorubicin in TNBC cells. Conclusions: From our in vitro data we conclude that C4 exerts cytostatic effects on triple-negative breast cancer cells via a pathway involving reactive oxygen species. Its potential value in combination with cytotoxic therapies merits deeper investigation in pre-clinical models. [ABSTRACT FROM AUTHOR]

Evaluation of in vitro cytotoxicity of several Cu chelating agents - 2,2′-biquinoline, 8-hydroxyquinoline (oxine), ammonium pyrrolidinedithiocarbamate (APDTC), di-2-pyridylketone-4,4,-dimethyl-3-thiosemicarbazone (Dp44mT), dithizone and neocuproine – on HT-29 human colon adenocarcinoma as well as long term in vitro cytostatic effect were assessed in the presence of Cu(II) ions. Intracellular Cu accumulation was observed for each chelating agent. Cytotoxicity was also investigated on HCT-15 and HCT-116 human colon adenocarcinomas, HT-1080 human fibrosarcoma, A-375 malignant melanoma, MCF-7, MDA-MB-231 and ZR-75-1 human breast adenocarcinomas as well as MeT-5A and P31wt mesothelioma. For both short and long term antiproliferative studies, each chelating agent proved to be much more effective in the presence of Cu(II) ions. Generally, the following cytotoxicity order could be established on each cell line: Dp44mT > neocuproine > APDTC > oxine > 2,2′ biquinoline ≈ dithizone. The IC 50 values even showed one order of magnitude difference among the cell lines. Considerable differences were also observed for colony formation and spheroid growth inhibition. Thus, for Dp44mT and neocuproine, practically no resistant cell line could be developed, whereas for the rest of the chelating agents the long term survival was ensured. By raising the Cu(II) concentration from 0.5 μM to 50 μM, dramatically higher apoptotic processes were induced for Dp44mT and oxine after just 20 min. Elevated Cu(II) concentration activated reactive oxygen species generation. The investigated chelating agents restored the DNA damage caused by free Cu(II). Thus, DNA is not the target of the intracellular Cu accumulation. However, DNA intercalation was observed for the Cu(II) and neocuproine combination. [ABSTRACT FROM AUTHOR]

Reflecting the known biological activity of isoniazid-based hydrazones, seventeen hydrazones of 4-(trifluoromethyl)benzohydrazide as their bioisosters were synthesized from various benzaldehydes and aliphatic ketones. The compounds were screened for their in vitro activity against Mycobacterium tuberculosis , nontuberculous mycobacteria ( M. avium , M. kansasii ), bacterial and fungal strains. The most antimicrobial potent derivatives were also investigated for their cytostatic and cytotoxic properties against three cell lines. Camphor-based molecule, 4-(trifluoromethyl)- N ′-(1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)benzohydrazide, exhibited the highest and selective inhibition of M. tuberculosis with the minimum inhibitory concentration (MIC) of 4 µM, while N ′-(4-chlorobenzylidene)-4-(trifluoromethyl)benzohydrazide was found to be superior against M. kansasii (MIC = 16 µM). N ′-(5-Chloro-2-hydroxybenzylidene)-4-(trifluoromethyl)benzohydrazide showed the lowest MIC values for gram-positive bacteria including methicillin-resistant Staphylococcus aureus as well as against two fungal strains of Candida glabrata and Trichophyton mentagrophytes within the range of ≤0.49–3.9 µM. The convenient substitution of benzylidene moiety at the position 4 or the presence of 5-chloro-2-hydroxybenzylidene scaffold concomitantly with a sufficient lipophilicity are essential for the noticeable antimicrobial activity. This 5-chlorosalicylidene derivative avoided any cytotoxicity on two mammalian cell cultures (HepG2, BMM Φ ) up to the concentration of 100 µM, but it affected the growth of MonoMac6 cells. [ABSTRACT FROM AUTHOR]

Metal complexes are still broadly used as the first line of the treatment for different types of tumors nowadays. Carboplatin and oxaliplatin were authorized for clinical use, even though there is little information on the mutagenic profile associated to their usage. This study evaluated the cytostatic effects and the induction of complex genomic alterations after 24-h treatment of CHO-K1 cells to concentrations of 12.5–800 μM of carboplatin and oxaliplatin in the cytokinesis-block micronucleus assay (CBMN-Cyt). The results demonstrated that carboplatin and oxaliplatin significantly increased the frequency of micronuclei (MN), nucleoplasmatic bridges (NPBs), and nuclear buds (NBUDs). On one hand, oxaliplatin induces significantly more chromosomal abnormalities than carboplatin at concentrations of 12.5 and 25 μM. On the other hand, carboplatin, in cells exposed to concentrations of 50 and 100 μM, is more efficient than oxaliplatin in the induction of chromosomal instability events. Both drugs cause significant reduction in the cytokinesis-block proliferation index, demonstrating their cytostatic effects at concentrations 50–800 μM. The results of this study shed more light on the characterization of biological effects associated with the exposure to carboplatin and oxaliplatin. [ABSTRACT FROM AUTHOR]

We have previously reported that combined inhibition of the epidermal growth factor receptor by erlotinib and of RAC1 by NSC23766 yielded a synergistic antiproliferative effect on established and primary cultured glioblastoma cells. The current study aimed at identifying the molecular mechanism. Staining for annexin V/PI or carboxyfluorescein succinimidyl ester was performed in order to determine the induction of apoptosis, necrosis or cytostasis in established and primary cultured glioblastoma cells. Moreover, expression of Ki-67 was determined by immunofluorescence, and the expression of cell cycle proteins was analysed by Western blot. Our data show that combined treatment with erlotinib and NSC23766 resulted in a reduced number of cell divisions, a significantly decreased Ki-67 expression, increased apoptosis and autophagy when compared to single agent treatments. On the molecular level, concomitant treatment with both agents resulted in a pronounced downregulation of cyclin D1, cyclin-dependent kinases 2, 4 and 6, as well as of survivin when compared to treatments with either agent alone. In conclusion, we demonstrate that combined treatment of human glioma cell lines in vitro with erlotinib and NSC23766 markedly inhibits cell division, induces apoptosis independent of caspase-3 activation and induces autophagy concomitant with suppression of survivin. [ABSTRACT FROM AUTHOR]

It was aimed to investigate the thioredoxin reductase 1 (TrxR1)-targeted anticancer effect of vulpinic (VA) and lecanoric (LA) acids, which are lichen secondary metabolites, on breast cancer MCF-7 and MDA-MB-453 cell lines, and to compare the effectiveness of this potential effect against commercial chemotherapeutic drugs carboplatin and docetaxel. The anticancer effects of both lichen metabolites were evaluated by XTT, flow cytometry analysis, cell scratch, and transwell migration assays. Apoptotic results were also confirmed by qPCR and western blot. Changes in TrxR1 were investigated in gene and protein expressions and enzyme activity levels. VA suppressed the proliferation of MCF-7 and MDA-MB-453 cells in a dose- and time-dependent manner, and the IC 50 values were calculated as 22.92 μg/ml and 95.65 μg/ml, respectively. As for LA, it did not have a considerable antiproliferative effect on both cell lines. VA had stronger cytotoxicity than both chemotherapeutic drug in MCF-7 cells and showed antiproliferative activity closer to carboplatin in MDA-MB-453 cells. qPCR, western blot, and flow cytometry analysis results revealed that VA did not induce apoptosis in both cell lines. In contrast, VA caused cell cycle arrest, significantly. Migration assay results showed that VA suppressed migration in both cells. VA induced the gene expression of TrxR1 while inhibiting its protein expression and enzymatic activity in both cell lines. The findings reveal that vulpinic acid may be a novel inhibitor candidate on TrxR1 and could be considered a potential chemotherapeutic agent for breast cancer treatment, especially in MCF-7 cells. [Display omitted] • Vulpinic acid (VA) induced cytotoxicity in human MCF-7 and MDA-MB-453 cell lines. • VA suppressed the cell migration in both cell types. • VA downregulated the protein expression and inhibited enzymatic activity of TrxR1. • VA showed its anticancer effect via targeting TrxR1 in breast cancer. [ABSTRACT FROM AUTHOR]

Based on the previously described antimicrobial activity of salicylanilide derivatives, we designed and synthesized novel 2-(phenylcarbamoyl)phenyl 4-substituted benzoates. The most active salicylanilides were selected for esterification by various 4-substituted benzoic acids. These compounds were evaluated in vitro against Mycobacterium tuberculosis , including multidrug-resistant strains, nontuberculous mycobacteria ( Mycobacterium avium and Mycobacterium kansasii ), and eight bacterial and fungal strains. We also investigated the cytostatic and cytotoxic actions of the esters. The minimum inhibitory concentrations (MICs) against mycobacteria ranged from 0.125 to 8 μM. Interestingly, the drug-resistant strains exhibited the highest susceptibility without any cross-resistance with established drugs. 4-Bromo-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl 4-nitrobenzoate showed the most potent inhibition with MIC values ranging from 0.25 to 2 μM. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus , were inhibited by two derivatives with MIC values of at least 0.49 μM, whereas Gram-negative bacteria and most of the tested fungi did not display any marked susceptibility. Benzoates exhibited no cytotoxicity at concentrations up to 50 μM but most caused significant cytostasis with IC 50 values lower than 10 μM. Some cytotoxicity-based selectivity indexes for drug-susceptible and drug-resistant M. tuberculosis as well as Staphylococci were higher than 100. These values indicate that some of these derivatives are promising candidates for future research. [ABSTRACT FROM AUTHOR]

Inhibition assays on tumour cells in vitro are commonly used to confirm the activity of extracts, fractions and compounds from plants reported to be antitumoural. The majority of assays report the IC 50 (50% inhibitory concentration), whereas others distinguish between inhibition of cell proliferation (cytostasis) and cell death (cytotoxicity). Here, we offer some suggestions as to the different types of assay, the cell lines that may be used, control cells and drugs, as well as the interpretation of the results. Using both theoretical considerations and experimental data, we specifically question the frequent overinterpretation of reported results regarding the selectivity for cancer cells of the plant extract or compound under study, concluding that this “selectivity” is due to a quantitative difference in cell proliferation rates, rather than a qualitative difference between normal and tumour cells. Inhibition assays will always represent one of the first steps in the discovery of clinically valuable new drugs, but these assays do not allow us to conclude that we have found the “magic bullet”. [ABSTRACT FROM AUTHOR]

Abstract: Four bis(thiosemicarbazonate)gold(III) complexes (1–4) with a general formula [Au(L)]Cl {L=L1, glyoxal-bis(N4-methylthiosemicarbazone); L2, glyoxal-bis(N4-ethylthiosemicarbazone); L3, diacetyl-bis(N4-methylthiosemicarbazone); L4, diacetyl-bis(N4-ethylthiosemicarbazone)} were synthesised and screened for activity against the human immunodeficiency virus (HIV). Complexes 1–4 were characterised using 1H-NMR and IR spectroscopy; and their purity established by micronanalysis. Complex 3 inhibited viral infection of TZM-bl cells by 98% (IC50 =6.8±0.6μM) at a non toxic concentration of 12.5μM while complex 4 inhibited infection of these cells by 72 and 98% (IC50 =5.3±0.4μM) at concentrations of 6.25 and 12.5μM respectively. The mechanism of inhibition of infection in TZM-bl cells is presumably as a result of the cytostatic or anti-proliferative activity that was observed for complex 4 in real time cell electronic sensing (RT-CES) and carboxyflourescein succinimidyl ester (CFSE) analysis. Treatment of T lymphocytes from HIV infected individuals with 4 decreased CD4+ T cell expression (p=0.0049) as demonstrated by multi-parametric flow cytometry without suppressing cytokine production. None of the ligands (L1–L4) demonstrated anti-viral activity, supporting the importance of metal (gold) complexation in these potential drugs. Complexes 3 and 4 were shown to have ideal lipophilicity values that were similar when shake flask (0.97±0.5 and 2.42±0.6) and in silico prediction (0.8 and 1.5) methods were compared. The activity and drug-like properties of complexes 3 and 4 suggests that these novel metal-based compounds could be combined with virus inhibitory drugs to work as cytostatic agents in the emerging class of anti-HIV drugs known as virostatics. [Copyright &y& Elsevier]

Abstract: Tumor necrosis factor (TNF) and the members of the interferon (IFN) family are major inducible cytokines that function to counteract viral infections or cellular transformation. Recently, our lab has characterized a novel antiviral state which is induced in primary human fibroblasts by co-treatment with TNF plus IFNβ. Here, we demonstrate that this synergistic state is both antiviral and cytostatic for primary human cells. Significantly, we observed that a wide spectrum of transformed human cancer cells have universally lost the ability to induce the TNF/IFNβ synergistic state, as defined by three separate criteria. We hypothesize that the ability to induce the TNF/IFNβ synergistic state is a unique feature of primary cells and is incompatible with cellular immortalization and/or transformation. [Copyright &y& Elsevier]

Abstract: Nitric oxide has varied effects on human breast cancer cells. At low concentration (micromolar range) it increases proliferation by increasing synthesis of some cells cycle protein and in higher concentration (nanomolar range) it leads to cytostasis or apoptosis by decreasing the translation of some cell cycle proteins. [Copyright &y& Elsevier]

Abstract: The Latent Membrane Protein 1 of the Epstein–Barr virus is required for human B lymphocyte immortalization and functions as a constitutively activated member of the TNF-receptor family, through recruitment of TRAFs and TRADD molecules on its Carboxy-terminal domain, leading to the activation of NF-κB and AP1 transcription factors. The formation of the signaling complexes requires LMP1 oligomerization, a role assigned to the membrane-spanning domains of the molecule. There is, however, increasing evidence that these membrane-spanning domains are not only confined to oligomerization but play a direct role in downregulation of promoter activity and cytostasis. Here, we describe a new inhibitory activity which is effective on viral or cellular promoters (even the endogenous ones), requires only membrane-spanning domains 3–4 or 5–6 and is neither associated with cytostasis nor with apoptosis. [Copyright &y& Elsevier]

Abstract: The identification of the TGFβ cytokine signaling pathway, including membrane receptor serine/threonine kinases and Smad transcription factors as their substrates, has allowed the delineation of a process for conversion of these signals into programs of gene activation and repression that underlie critical cell fate and developmental decisions. The deconstruction of one of these responses – the cell cycle arrest response – into its elemental molecular parts has shed light into the mechanisms used by tumors to evade surveillance and cause metastasis. [Copyright &y& Elsevier]

The present update describes the biological activities of an alpha fetoprotein (AFP)-derived peptide termed the growth-inhibitory peptide (GIP), which is a synthetic 34-amino acid segment produced from the native molecule. The GIP has been shown to be growth-suppressive in both fetal and tumor cells but not in adult cells. Even though its mechanism of action has not been completely elucidated, GIP has been shown to engage in cellular events such as endocytosis, cellular aggregation, hemagglution, and cytoskeleton-induced cell shape changes. The GIP was shown to be growth-suppressive in nine different human tumor types and to suppress the spread of tumor infiltrates and metastases in human and mouse mammary cancers. It was further found that the oligomeric state (cyclic vs. linear configuration) of the GIP determined its biological and anticancer efficacy. The combined properties of tumor growth suppression and reduction of tumor metastases represent promising areas for GIP as a chemotherapeutic agent. It was concluded that the GIP derived from full-length AFP represents a growth-inhibitory motif possessing intrinsic properties that allow it to interact in cell surface events such as tumor proliferation, progression, and metastasis. Copyright © 2006 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Thymosin fraction-5 (TF5), an array of small molecular weight peptides present in crude extracts of the adult bovine thymus, contains numerous constituents with demonstrable biological activity. Because TF5 generally enhances immune reactivity in a variety of settings, and additionally restricts proliferation of certain neoplasms, we examined the effects of TF5 on proliferative capacity in the human promyelocytic leukemia cell line HL-60. Vital dye-exclusion, oxidative metabolism of chromogenic dyes, and clonogenic growth profiles were monitored to assess rates of cellular proliferation; our results demonstrate that TF5 restricted HL-60 cell growth, an influence that exhibited comparable potency and efficacy among all three indices. This antiproliferative activity was labile, insofar as medium conditioned in HL-60 cells for 24 h became devoid of the initial growth-suppressive activity after 24-h culture when subsequently administered to naïve cultures. Review of cytoarchitectural traits, chromatin staining by TUNEL, and fluorescent cytometric analyses demonstrated that TF5 failed to elicit apoptosis, however, suggesting that this material instead drove treated cells into growth arrest and an unanticipated cytostasis. Qualitatively similar responses were noted in the human monoblastic leukemia cell line U937. Partial purification of TF5 by FPLC yielded a component containing an antiproliferative activity associated with the ∼1000-Da fraction. These results demonstrate that TF5 contains a sub-fraction possessing a growth-suppressive activity capable of restraining normal proliferation of human myeloid neoplasms via the apparent induction of true cytostasis. [Copyright &y& Elsevier]

The number of proliferating cells in the rodent retina declines dramatically after birth. To determine if extrinsic factors in the retinal micro-environment are responsible for this decline in proliferation, we established cultures of retinal progenitors or Müller glia, and added dissociated retinal neurons from older retinas. The older cells inhibited proliferation of progenitor cells and Müller glia. When these experiments were performed in the presence of TGFβRII-Fc fusion protein, an inhibitor of TGFβ signaling, proliferation was restored. This suggests a retina-derived TGFβ signal is responsible for the developmental decline in retinal proliferation. TGFβ receptors I and II are expressed in the retina and are located in nestin-positive progenitors early in development and glast-positive Müller glia later in development. RT-PCR and immunofluorescence data show TGFβ2 is the most highly expressed TGFβ ligand in the postnatal retina, and it is expressed by inner retinal neurons. Addition of either TGFβ1 or TGFβ2 to postnatal day 4 retinas significantly inhibited progenitor proliferation, while treatment of explanted postnatal day 6 retinas with TGFβ signaling inhibitors resulted in increased proliferation. Last, we tested the effects of TGFβ in vivo by injections of TGFβ signaling inhibitors: when TGFβ signaling is inhibited at postnatal day 5.5, proliferation is increased in the central retina; and when co-injected with EGF at postnatal day 10, TGFβ inhibitors stimulate Müller glial proliferation. In sum, these results show that retinal neurons produce a cytostatic TGFβ signal that maintains mitotic quiescence in the postnatal rat retina. [ABSTRACT FROM AUTHOR]

Abstract: Recently, there has been a great interest in the effects of different types of n-6 polyunsaturated acids (n-6 PUFAs) upon the immune system and cancer development. However, the effects of n-6 PUFAs are still controversial and as yet undefined. The present study aimed to investigate the anti-tumor effects of n-6 PUFAs against EL4 thymoma and the associated immune mechanisms. To this, sesame oil, a vegetable oil enriched with n-6 PUFAs, or free linoleic acid (LA) were administered intraperitoneally into C57BL/6 mice before and after challenge with EL4 lymphoma cells. Treatment with either sesame oil or LA attenuated the growth and metastasis of EL4 lymphoma. The anti-tumor effect of LA was superior to that of sesame oil, and associated with an increase in the survival rate of the tumor-bearing mice. In addition, both sesame oil and LA showed dose-dependent anti-lymphoma growth in vitro. Treatment with LA generated significant increases in the anti-lymphoma cytolytic and cytostatic activities of T cells and macrophages, respectively, and enhanced production of IL-2 and IFN-γ while decreased production of IL-4, IL-6 and IL-10. In summation, the results suggest that n-6 PUFAs, represented by LA, can attenuate EL4 lymphoma growth and metastasis through enhancing the specific and non-specific anti-tumor cytolytic activities and production of TH1 cytokines. These findings might be of great importance for a proper design of systemic nourishment with PUFAs emulsions for cancer patients. [Copyright &y& Elsevier]

The resin of Commiphora erlangeriana is known to be poisonous to humans and animals and has traditionally been used as an arrow poison. Since recent phytochemical studies on this plant material has identified four major lignans (named, Erlangerins A to D) that closely relate to the structure of podophyllotoxin, it was hypothesised that the well known poisoning effect of the resin could in part be due to direct toxicity to mammalian cells. Hence, the toxicity of Erlangerins was studied by measuring the viability of two human (HeLa and EAhy926) and two murine (L929 and RAW 264.7) cell lines. As assessed by the MTT assay, the effect of Erlangerin C and D closely follow the activity profile of podophyllotoxin: they induced a concentration-dependent cytotoxicity in the murine macrophage cells (RAW 264.7) and a cytostatic effect in HeLa, EAhy926 and L929 cells. In contrast, Erlangerins A and B suppressed cell viability at relatively higher concentrations (EC50 values higher than 3 μM as compared with nM concentration range for Erlangerins C and D and podophyllotoxin) and their activity appears to be consistent with a cytotoxic mode of action in all cell lines studied. The structure–activity-relationship established from the study is discussed. [Copyright &y& Elsevier]

We previously showed that an overproduction of nitric oxide (NO) by macrophages was responsible for the collapse of lymphoproliferative responses after burn injury in rats. First, we demonstrate here that 10 days post-burn, the inhibition of splenocyte response to concanavalin-A results from cytostatic, apoptotic, and necrotic effects of NO on activated T cells. This was evidenced by various criteria at the levels of DNA, mitochondria, and plasma membrane. Inhibition of NO synthase by S-methylisothiourea (10 μM) normalized all the parameters. Second, we show that two soluble guanylate cyclase (sGC) inhibitors, LY83583 and ODQ, restored the proliferative response in a concentration-dependent manner. LY83583 (0.5 μM) rescued T cells from apoptosis. Similar results were obtained with KT5823 (5 μM) a specific inhibitor of protein kinase G (PKG). In contrast, neither LY83583 nor KT5823 inhibited NO-induced necrosis. These results suggest that NO blocked T cells in the G1 phase and induced apoptosis through a sGC-PKG-dependent pathway and necrosis through an independent one. [Copyright &y& Elsevier]

Two acidic glycosphingolipids (gangliosides) derived from mouse macrophage membranes and separated by thin-layer chromatography have a strong cytostatic effect on human and mouse tumor cells. The structure of the two gangliosides, named MphiG1 and MphiG2, was elucidated by application of physicochemical and immunochemical methods. Gas chromatography and mass spectrometry of MphiG1 and MphiG2 classified them as isomeric monosialogangliosides with ceramide moieties composed of sphingosine as the long-chain base, C[sub 16] and C[sub 18] fatty acids, respectively, and a lacto-tetraose backbone. For MphiG1, additional immunochemical findings led to the proposed structure IV[sup 3]NeuAc-nLcOse[sub 4]Cer. The immunochemical reactions of MphiG2 suggest a branched structure for the oligosaccharide moiety. [ABSTRACT FROM AUTHOR]

The increasing incidence of melanoma and the poor responsiveness of disseminated disease to conventional treatments call for the development of new therapeutic approaches. Phenylacetate, a nontoxic differentiation inducer, can suppress the growth of other neuro- ectodermal tumors, i.e., gliomas, in laboratory models and in humans. This finding led us to explore the efficacy of phenylacetate and related aromatic fatty acids in melanoma. Phenylacetate and phenylbutyrate were found to a) induce selective cytostasis and maturation of cultured human melanoma cells, b) modulate the expression of genes implicated in tumor metastasis (type IV collagenase and tissue inhibitor of metalloproteinases-2) and immunogenicity (HLA class I); and c) enhance the efficacy of other agents of clinical interest, including retinoids, interferon-alpha, suramin, and 5-aza-2'-deoxycytidine. Reflecting on the phenotypic heterogeneity of melanoma, the degree of biologic alterations induced by phenylacetate, phenylbutyrate varied significantly among the tumor cell lines tested. Although losing invasive capacity and tumorigenicity in athymic mice, poorly differentiated cells exhibited only a marginal change in morphology, remained amelanotic, and resumed growth after treatment was discontinued. By contrast, treatment of melanoma cells that were in a more advanced stage of maturation resulted in profound alterations in cell growth, morphology, and pigmentation consistent with terminal differentiation. The in vitro antitumor activity was observed with nontoxic, pharmacologic concentrations of phenylacetate and phenylbutyrate, suggesting potential clinical use of these drugs in the treatment of melanomas. [ABSTRACT FROM AUTHOR]

The objective was to investigate the anti-cancer effects and underlying molecular mechanisms of cytostasis which were activated by an anti-microtubule drug, ABT-751, in two urinary bladder urothelial carcinoma (UBUC)-derived cell lines, BFTC905 and J82, with distinct genetic backgrounds. A series of in vitro assays demonstrated that ABT-751 induced G2/M cell cycle arrest, decreased cell number in the S phase of the cell cycle and suppressed colony formation/independent cell growth, accompanied with alterations of the protein levels of several cell cycle regulators. In addition, ABT-751 treatment significantly hurdled cell migration and invasion along with the regulation of epithelial–mesenchymal transition-related proteins. ABT-751 triggered autophagy and apoptosis, downregulated the mechanistic target of rapamycin kinase (MTOR) and upregulated several pro-apoptotic proteins that are involved in extrinsic and intrinsic apoptotic pathways. Inhibition of autophagosome and autolysosome enhanced apoptosis was also observed. Through the inhibition of the NFκB signaling pathway, ABT-751 suppressed S-phase kinase associated protein 2 (SKP2) transcription and subsequent translation by downregulation of active/phospho-AKT serine/threonine kinase 1 (AKT1), component of inhibitor of nuclear factor kappa B kinase complex (CHUK), NFKB inhibitor alpha (NFKBIA), nuclear RELA proto-oncogene, NFκB subunit (RELA) and maintained a strong interaction between NFKBIA and RELA to prevent RELA nuclear translocation for SKP2 transcription. ABT-751 downregulated stable/phospho-SKP2 including pSKP2(S64) and pSKP2(S72), which targeted cyclin-dependent kinase inhibitors for degradation through the inactivation of AKT. Our results suggested that ABT-751 may act as an anti-cancer drug by inhibiting cell migration, invasion yet inducing cell cycle arrest, autophagy and apoptosis in distinct UBUC-derived cells. Particularly, the upstream molecular mechanism of its anticancer effects was identified as ABT-751-induced cytostasis through the inhibition of SKP2 at both transcriptional and post-translational levels to stabilize cyclin dependent kinase inhibitor 1A (CDKN1A) and CDKN1B proteins. [ABSTRACT FROM AUTHOR]

Persistent virus infection continuously produces non-self nucleic acids that activate cell-intrinsic immune responses. However, the antiviral defense evolved as a transient, acute phase response and the effects of persistently ongoing stimulation onto cellular homeostasis are not well understood. To study the consequences of long-term innate immune activation, we expressed the NS5B polymerase of Hepatitis C virus (HCV), which in absence of viral genomes continuously produces immune-stimulatory RNAs. Surprisingly, within 3 weeks, NS5B expression declined and the innate immune response ceased. Proteomics and functional analyses indicated a reduced proliferation of those cells most strongly stimulated, which was independent of interferon signaling but required mitochondrial antiviral signaling protein (MAVS) and interferon regulatory factor 3 (IRF3). Depletion of MAVS or IRF3, or overexpression of the MAVS-inactivating HCV NS3/4A protease not only blocked interferon responses but also restored cell growth in NS5B expressing cells. However, pan-caspase inhibition could not rescue the NS5B-induced cytostasis. Our results underline an active counter selection of cells with prolonged innate immune activation, which likely constitutes a cellular strategy to prevent persistent virus infections. [ABSTRACT FROM AUTHOR]

p21-activated protein kinase (PAK2) is a unique member of the PAK family kinases that plays important roles in stress signaling. It can be activated by binding to the small GTPase, Cdc42 and Rac1, or by caspase 3 cleavage. Cdc42-activated PAK2 mediates cytostasis, whereas caspase 3-cleaved PAK2 contributes to apoptosis. However, the relationship between these two states of PAK2 activation remains elusive. In this study, through protein biochemical analyses and various cell-based assays, we demonstrated that full-length PAK2 activated by Cdc42 was resistant to the cleavage by caspase 3 in vitro and within cells. When mammalian cells were treated by oxidative stress using hydrogen peroxide, PAK2 was highly activated through caspase 3 cleavage that led to apoptosis. However, when PAK2 was pre-activated by Cdc42 or by mild stress such as serum deprivation, it was no longer able to be cleaved by caspase 3 upon hydrogen peroxide treatment, and the subsequent apoptosis was also largely inhibited. Furthermore, cells expressing active mutants of full-length PAK2 became more resistant to hydrogen peroxide-induced apoptosis than inactive mutants. Taken together, this study identified two states of PAK2 activation, wherein Cdc42- and autophosphorylation-dependent activation inhibited the constitutive activation of PAK2 by caspase cleavage. The regulation between these two states of PAK2 activation provides a new molecular mechanism to support PAK2 as a molecular switch for controlling cytostasis and apoptosis in response to different types and levels of stress with broad physiological and pathological relevance. • PAK2 can promote cell survival or apoptosis in response to different stresses. • Cdc42 and caspase 3 can activate PAK2. However, their relationship remains unclear. • Autophosphorylation of PAK2 inhibits its activation by caspase 3 cleavage. • Cdc42-activated PAK2 prevents its constitutive activation by caspase 3 in cells. • Moderate stress primes cells resistant to apoptosis via PAK2 partial activation. [ABSTRACT FROM AUTHOR]

Primary liver cancer is one of the leading causes for cancer-related death worldwide. Transforming growth factor beta (TGF-β) is a pleiotropic cytokine that signals through membrane receptors and intracellular Smad proteins, which enter the nucleus upon receptor activation and act as transcription factors. TGF-β inhibits liver tumorigenesis in the early stage by inducing cytostasis and apoptosis, but promotes malignant progression in more advanced stages by enhancing cancer cell survival, EMT, migration, invasion and finally metastasis. Understanding the molecular mechanisms underpinning the multi-faceted roles of TGF-β in liver cancer has become a persistent pursuit during the last two decades. Contextual regulation fine-tunes the robustness, duration and plasticity of TGF-β signaling, yielding versatile albeit specific responses. This involves multiple feedback and feed-forward regulatory loops and also the interplay between Smad signaling and non-Smad pathways. This review summarizes the known regulatory mechanisms of TGF-β signaling in liver cancer, and how they channel, skew and even switch the actions of TGF-β during cancer progression. [ABSTRACT FROM AUTHOR]

Background: Capacitive-resistive electric transfer (CRET) is a non-invasive therapeutic strategy that applies radiofrequency electric currents within the 400-600 kHz range to tissue repair and regeneration. Previous studies by our group have shown that 48 h of intermittent exposure to a 570 kHz CRET signal at a subthermal density of 50 μA/mm2 causes significant changes in the expression and activation of cell cycle control proteins, leading to cycle arrest in human cancer cell cultures. The present study investigates the relevance of the signal frequency in the response of the human neuroblastoma cell line NB69 to subthermal electric treatment with four different signal frequency currents within the 350-650 kHz range.Methods: Trypan blue assay, flow cytometry, immunofluorescence and immunoblot were used to study the effects of subthermal CRET currents on cell viability, cell cycle progression and the expression of several marker proteins involved in NB69 cell death and proliferation.Results: The results reveal that among the frequencies tested, only a 448 kHz signal elicited both proapoptotic and antiproliferative, statistically significant responses. The apoptotic effect would be due, at least in part, to significant changes induced by the 448 kHz signal in the expression of p53, Bax and caspase-3. The cytostatic response was preceded by alterations in the kinetics of the cell cycle and in the expression of proteins p-ERK1/2, cyclin D1 and p27, which is consistent with a potential involvement of the EGF receptor in electrically induced changes in the ERK1/2 pathway. This receives additional support from results indicating that the proapototic and antiproliferative responses to CRET can be transiently blocked when the electric stimulus is applied in the presence of PD98059, a chemical inhibitor of the ERK1/2 pathway.Conclusion: The understanding of the mechanisms underlying the ability of slowing down cancer cell growth through electrically-induced changes in the expression of proteins involved in the control of cell proliferation and apoptosis might afford new insights in the field of oncology. [ABSTRACT FROM AUTHOR]

Summary Transition metals are essential, but deregulation of their metabolism causes toxicity. Here, we report that the compound NSC319726 binds copper to induce oxidative stress and arrest glioblastoma-patient-derived cells at picomolar concentrations. Pharmacogenomic analysis suggested that NSC319726 and 65 other structural analogs exhibit lethality through metal binding. Although NSC319726 has been reported to function as a zinc ionophore, we report here that this compound binds to copper to arrest cell growth. We generated and validated pharmacogenomic predictions: copper toxicity was substantially inhibited by hypoxia, through an hypoxia-inducible-factor-1α-dependent pathway; copper-bound NSC319726 induced the generation of reactive oxygen species and depletion of deoxyribosyl purines, resulting in cell-cycle arrest. These results suggest that metal-induced DNA damage may be a consequence of exposure to some xenobiotics, therapeutic agents, as well as other causes of copper dysregulation, and reveal a potent mechanism for targeting glioblastomas. [ABSTRACT FROM AUTHOR]