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PTEN is a tumor suppressor gene mutated in many human cancers, and its expression is reduced or absent in almost half of hepatoma patients. We used the Cre-loxP system to generate a hepatocyte-specific null mutation of Pten in mice (AlbCrePten(flox/flox) mice). AlbCrePten(flox/flox) mice showed massive hepatomegaly and steatohepatitis with triglyceride accumulation, a phenotype similar to human nonalcoholic steatohepatitis. Adipocyte-specific genes were induced in mutant hepatocytes, implying adipogenic-like transformation of these cells. Genes involved in lipogenesis and beta-oxidation were also induced, possibly as a result of elevated levels of the transactivating factors PPARgamma and SREBP1c. Importantly, the loss of Pten function in the liver led to tumorigenesis, with 47% of AlbCrePten(flox/flox) livers developing liver cell adenomas by 44 weeks of age. By 74-78 weeks of age, 100% of AlbCrePten(flox/flox) livers showed adenomas and 66% had hepatocellular carcinomas. AlbCrePten(flox/flox) mice also showed insulin hypersensitivity. In vitro, AlbCrePten(flox/flox) hepatocytes were hyperproliferative and showed increased hyperoxidation with abnormal activation of protein kinase B and MAPK. Pten is thus an important regulator of lipogenesis, glucose metabolism, hepatocyte homeostasis, and tumorigenesis in the liver. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to investigate the effect of plasma‐activated Ringer's lactate solution (PAL) on oral squamous cell carcinoma (OSCC) cells and carcinogenic processes with a particular focus on iron and collagenous matrix formation. Materials and Methods: We used three OSCC cell lines, one keratinocyte cell line, and two fibroblast lines, and cell viability assays, immunoblotting, flow cytometry, and transmission electron microscopy were performed to evaluate the effect and type of cell death. The effect of PAL treatment on lysyl oxidase (LOX) expression was investigated in vitro and in vivo. Tamoxifen‐inducible Mob1a/b double‐knockout mice were used for the in vivo experiment. Results: PAL killed OSCC cells more effectively than the control nontumorous cells and suppressed cell migration and invasion. Ferroptosis occurred and the protein level of LOX was downregulated in cancer cells in vitro and in vivo. Additionally, PAL improved the survival rate of mice and suppressed collagenous matrix formation. Conclusions: We demonstrated that PAL specifically kills OSCC cells and that ferroptosis occurs in vitro and in vivo. Furthermore, PAL can prevent carcinogenesis and improve the survival rate of oral cancer, especially tongue cancer, by changing collagenous matrix formation via LOX suppression. [ABSTRACT FROM AUTHOR]

Abstract: To investigate the effects of nanoparticle-rich diesel exhaust (NR-DE) on adrenocortical function, seven-week-old male mice were divided into four groups and exposed to either whole NR-DE at low (41.73μg/m3, 8.21×105 particles/cm3), high (152.01μg/m3, 1.80×106 particles/cm3) concentrations, filtered diesel exhaust (F-DE) or clean air for 8 weeks (5h/day, 5 days/week). After 8 weeks of exposure, the animals were euthanized under pentobarbital anesthesia and the blood samples were collected to detect serum progesterone and corticosterone. In addition, adrenal glands were excised, and adrenal cells were cultured in the absence or presence of rat adrenocorticotropic hormone (ACTH) (10−15 to 10−10 M) for 4h. There were no significant differences in the body weight, absolute and relative adrenal gland weight among the groups. Serum concentration of corticosterone and progesterone was not changed significantly. Administration of ACTH resulted in a dose-dependent increase in corticosterone and progesterone release in mice-exposed to low-concentration NR-DE and clean air. Moreover, corticosterone and progesterone concentrations in adrenal cells increased significantly in mice-exposed to low-concentration NR-DE basal and administrated with ACTH (10−15 to 10−11 M for corticosterone; 10−14 to 10−11 M for progesterone) compared with the control mice. In contrast, the concentration of corticosterone and progesterone decreased significantly in mice-exposed to high-concentration NR-DE or F-DE basal and administrated with ACTH (10−12 to 10−10 M for corticosterone; 10−15 to 10−10 M for progesterone) compared with the control mice. These results suggest that exposure to NR-DE or F-DE may disrupt adrenocortical function in adult male mice. [Copyright &y& Elsevier]

PTEN is a tumor suppressor gene but whether cancer can develop in all PTEN-deficient cells is not known. In T cell-specific PTEN-deficient (tPTEN-/-) mice, which suffer from mature T cell lymphomas, we found that premalignancy, as defined by elevated AKT and senescence pathways, starts in immature T cell precursors and surprisingly not in mature T cells. Premalignancy only starts in 6-week-old mice and becomes much stronger in 9-week-old mice although PTEN is lost since birth. tPTEN-/- immature T cells do not become tumors, and senescence has no role in this model because these cells exist in a novel cell cycle state, expressing proliferating proteins but not proliferating to any significant degree. Instead, the levels of p27kip1, which is lower in tPTEN-/- immature T cells and almost nonexistent in tPTEN-/- mature T cells, correlate with the proliferation capability of these cells. Interestingly, transient reduction of these cancer precursor cells in adult tPTEN-/- mice within a crucial time window significantly delayed lymphomas and mouse lethality. Thus, loss of PTEN alone is not sufficient for cells to become cancerous, therefore other developmental events are necessary for tumor formation. [ABSTRACT FROM AUTHOR]

RalGTPase-activating protein (RalGAP) is an important negative regulator of small GTPases RalA/B that mediates various oncogenic signaling pathways in various cancers. Although the Ral pathway has been implicated in prostate cancer (PCa) development and progression, the significance of RalGAP in PCa has been largely unknown. We examined RalGAPα2 expression using immunohistochemistry on two independent tissue microarray sets. Both datasets demonstrated that the expression of RalGAPα2 was significantly downregulated in PCa tissues compared to adjacent benign prostatic epithelia. Silencing of RalGAPα2 by short hairpin RNA enhanced migration and invasion abilities of benign and malignant prostate epithelial cell lines without affecting cell proliferation. Exogenous expression of wild-type RalGAP, but not the GTPase-activating protein activity-deficient mutant of RalGAP, suppressed migration and invasion of multiple PCa cell lines and was phenocopied by pharmacological inhibition of RalA/B. Loss of Ralgapa2 promoted local microscopic invasion of prostatic intraepithelial neoplasia without affecting tumor growth in a Pten -deficient mouse model for prostate tumorigenesis. Our findings demonstrate the functional significance of RalGAP downregulation to promote invasion ability, which is a property necessary for prostate carcinogenesis. Thus, loss of RalGAP function has a distinct role in promoting progression from prostatic intraepithelial neoplasia to invasive adenocarcinoma. [ABSTRACT FROM AUTHOR]

Mammalian STE20‐like protein kinase 1/2 (MST1/2) and nuclear Dbf2‐related kinase 1/2 (NDR1/2) are core components of Hippo signaling that are also known to be important regulators of lymphocyte trafficking. However, little is understood about the roles of other Hippo pathway molecules in these cells. Here, we present the first analysis of the function of Mps one binder kinase activator‐1 (MOB1) in T lymphocytes in vivo. T‐cell‐specific double knockout (DKO) of MOB1A/B in mice [tMob1 DKO mice] reduces the number of naïve T cells in both the circulation and secondary lymphoid organs, but leads to an accumulation of CD4+CD8− and CD4−CD8+ single‐positive (SP) cells in the thymus. In vitro, naïve MOB1A/B‐deficient T cells show increased apoptosis and display impaired trafficking capacity in response to the chemokine CCL19. These defects are linked to suppression of the activation of MST and NDR kinases, but are independent of the downstream transcriptional co‐activator Yes‐associated protein 1 (YAP1). Thus, MOB1 proteins play an important role in thymic egress and T‐cell survival that is mediated by a pathway other than conventional Hippo‐YAP1 signaling. [ABSTRACT FROM AUTHOR]

Objective: MOB1, a core component of the Hippo signaling pathway, suppresses cell proliferation, and MOB1 liver conditional knockout mice develop intrahepatic cholangiocarcinoma (ICC). However, its clinical significance in human ICC has not been established. The aim of this study was to characterize protein levels and the role of Hippo and TGF pathways in ICCs. Methods: The protein levels of yes-associated protein 1 (YAP1), MOB1, Smad2, and TGFβ2 in 88 ICC cases were analyzed. Protein level was graded by a scoring system; then, the clinicopathological factors, including prognosis, were analyzed based on protein level. Results: Nuclear overexpression of YAP1 was seen in 28 cases (31.8%), and it was significantly associated with a poor overall survival rate (p = 0.01). MOB1 expression decreased in 42 cases (47.7%) and was associated with a poor overall survival rate (p = 0.02). SMAD2 nuclear localization was significantly correlated with a high YAP1 level independent of TGFβ2. Multivariate analysis revealed that a high YAP1 level, a low MOB1 level, and lymphatic permeation were independent risk factors for overall survival. Conclusions: These results showed that key components of the Hippo signaling pathway are aberrantly expressed and associated with the malignant potential of human ICC. [ABSTRACT FROM AUTHOR]

PTEN is a tumor suppressor gene mutated in many human cancers. We generated a bronchioalveolar epithelium-specific null mutation of Pten in mice [SP-C-rtTA/(tetO)(7)-Cre/Pten(flox/flox) (SOPten(flox/flox)) mice] that was under the control of doxycycline. Ninety percent of SOPten(flox/flox) mice that received doxycycline in utero [SOPten(flox/flox)(E10-16) mice] died of hypoxia soon after birth. Surviving SOPten(flox/flox)(E10-16) mice and mice that received doxycycline postnatally [SOPten(flox/flox)(P21-27) mice] developed spontaneous lung adenocarcinomas. Urethane treatment accelerated number and size of lung tumors developing in SOPten(flox/flox) mice of both ages. Histological and biochemical examinations of the lungs of SOPten(flox/flox)(E10-16) mice revealed hyperplasia of bronchioalveolar epithelial cells and myofibroblast precursors, enlarged alveolar epithelial cells, and impaired production of surfactant proteins. Numbers of bronchioalveolar stem cells (BASCs), putative initiators of lung adenocarcinomas, were increased. Lungs of SOPten(flox/flox)(E10-16) mice showed increased expression of Spry2, which inhibits the maturation of alveolar epithelial cells. Levels of Akt, c-Myc, Bcl-2, and Shh were also elevated in SOPten(flox/flox)(E10-16) and SOPten(flox/flox)(P21-27) lungs. Furthermore, K-ras was frequently mutated in adenocarcinomas observed in SOPten(flox/flox)(P21-27) lungs. These results indicate that Pten is essential for both normal lung morphogenesis and the prevention of lung carcinogenesis, possibly because this tumor suppressor is required for BASC homeostasis. [ABSTRACT FROM AUTHOR]

Leptin and insulin have been identified as fuel sensors acting in part through their hypothalamic receptors to inhibit food intake and stimulate energy expenditure. As their intracellular signaling converges at the PI3K pathway, we directly addressed the role of phosphatidylinositol3,4,5-trisphosphate-mediated (PIP3-mediated) signals in hypothalamic proopiomelanocortin (POMC) neurons by inactivating the gene for the PIP3 phosphatase Pten specifically in this cell type. Here we show that POMC-specific disruption of Pten resulted in hyperphagia and sexually dimorphic diet-sensitive obesity. Although leptin potently stimulated Stat3 phosphorylation in POMC neurons of POMC cell-restricted Pten knockout (PPKO) mice, it failed to significantly inhibit food intake in vivo. POMC neurons of PPKO mice showed a marked hyperpolarization and a reduction in basal firing rate due to increased ATP-sensitive potassium (KATP) channel activity. Leptin was not able to elicit electrical activity in PPKO POMC neurons, but application of the PI3K inhibitor LY294002 and the KATP blocker tolbutamide restored electrical activity and leptin-evoked firing of POMC neurons in these mice. Moreover, icv administration of tolbutamide abolished hyperphagia in PPKO mice. These data indicate that PIP3-mediated signals are critical regulators of the melanocortin system via modulation of KATP channels. [ABSTRACT FROM AUTHOR]