EPIGALLOCATECHIN-3-GALLATE TRIGGERS AUTOPHAGY MEDIATED CELL DEATH VIA UP-REGULATION OF TMEM74 GENE EXPRESSION IN CHRONIC MYELOID LEUKEMIA CELLS

5th International Eurasian Hematology Congress -- OCT 15-19, 2014 -- Antalya, TURKEYWOS: 00034724420015

Ubiquitously expressed hematological and neurological expressed 1 downregulates Akt-mediated GSK3ß signaling, and its knockdown results in deregulated G2/M transition in prostate cells

PubMed ID: 21323578As the molecular mechanism of ß-catenin deregulation is not well understood, and stabilized ß-catenin is known to translocate into the nucleus and activate genes for proliferation, a novel regulatory factor, hematological and neurological expressed 1 (HN1), for Akt-GSK3ß-ß- catenin axis is reported here. In our studies, HN1 gene structure was characterized. HN1 expression was found to be epidermal growth factor-responsive in PC-3 cells, and protein expression was also upregulated in PC-3 and LNCaP but not in DU145 cells. Additionally, HN1 was found to be downregulated by the specific AKT inhibitor wortmannin but not with PI3K or MAPK inhibitors, LY294002 and PD98059, respectively, in PC-3 and MCF-7 cells. Further, siRNA-mediated knockdown of HN1 resulted in considerable increase in Akt (S473) and GSK3ß (S9),(Y216) phosphorylations; moreover, subsequent accumulation of ß-catenin, increase in c-myc expression, and nuclear accumulation of cyclin D1 were observed in PC-3 cells. Knockdown of HN1 also resulted in prolongation of G 1 phase in cell cycle, increasing tetraploidy, presumably because of cells escaping from abnormal mitosis in PC-3 cells. Consistently, overexpression of HN1 reversed the cell-cycle-specific observations, resulted in accumulation of cells in G 2/M, and reduced the proliferation rate, which were investigated using flow cytometry and methylthiazol tetrazolium assays. As activating mutations of ß-catenin have been demonstrated in late-stage tumors, and ß-catenin stabilization was correlated with poor prognosis in previous reports, epidermal growth factor-upregulated HN1 expression might have a role in deregulating the AKT-GSK3ß (S9)-mediated signaling as a novel compensating mechanism. © 2011 Mary Ann Liebert, Inc

TNFα-Mediated Loss of β-Catenin/E-Cadherin Association and Subsequent Increase in Cell Migration Is Partially Restored by NKX3.1 Expression in Prostate Cells

Inflammation-induced carcinogenesis is associated with increased proliferation and migration/invasion of various types of tumor cells. In this study, altered β-catenin signaling upon TNFα exposure, and relation to loss of function of the tumor suppressor NKX3.1 was examined in prostate cancer cells. We used an in vitro prostate inflammation model to demonstrate altered sub-cellular localization of β-catenin following increased phosphorylation of Akt(S473) and GSK3β(S9). Consistently, we observed that subsequent increase in β-catenin transactivation enhanced c-myc, cyclin D1 and MMP2 expressions. Consequently, it was also observed that the β-catenin-E-cadherin association at the plasma membrane was disrupted during acute cytokine exposure. Additionally, it was demonstrated that disrupting cell-cell interactions led to increased migration of LNCaP cells in real-time migration assay. Nevertheless, ectopic expression of NKX3.1, which is degraded upon proinflammatory cytokine exposure in inflammation, was found to induce the degradation of β-catenin by inhibiting Akt(S473) phosphorylation, therefore, partially rescued the disrupted β-catenin-E-cadherin interaction as well as the cell migration in LNCaP cells upon cytokine exposure. As, the disrupted localization of β-catenin at the cell membrane as well as increased Akt(S308) priming phosphorylation was observed in human prostate tissues with prostatic inflammatory atrophy (PIA), high-grade prostatic intraepithelial neoplasia (H-PIN) and carcinoma lesions correlated with loss of NKX3.1 expression. Thus, the data indicate that the β-catenin signaling; consequently sub-cellular localization is deregulated in inflammation, associates with prostatic atrophy and PIN pathology