TUG1 promotes diabetic atherosclerosis by regulating proliferation of endothelial cells via Wnt pathway.

OBJECTIVE: To explore the specific role of TUG1 in regulating the occurrence and progression of diabetic atherosclerosis and its underlying mechanism. PATIENTS AND METHODS: TUG1 expressions in coronary artery disease (CAD) tissues, normal arterial tissues, endothelial cells induced by high-dose glucose and tumor necrosis factor-α (TNF-α) were detected by quantitative Real-time polymerase chain reaction (qRT-PCR). The effects of TUG1 on proliferation, migration and cell cycle of human umbilical vein endothelial cells (HUVECs) were detected by cell counting kit-8 (CCK-8), transwell assay and flow cytometry, respectively. Subsequently, protein expressions of proliferation-related genes, cell cycle-related genes and Wnt pathway-related genes were detected by Western blot after altering TUG1 expression in HUVECs. Further rescue experiments were carried out to explore whether TUG1 could regulate diabetic atherosclerosis via Wnt pathway. RESULTS: Overexpressed TUG1 was found in CAD tissues and endothelial cells induced by high-dose glucose and TNF-α compared with those of controls. TUG1 overexpression remarkably promoted proliferation, migration and cell cycle of HUVECs. Protein expressions of ß-catenin and c-Myc were upregulated by overexpression of TUG1. Rescue experiments indicated that XAV-939, the inhibitor of Wnt pathway, could partially reverse the increased proliferative and migratory changes in HUVECs induced by TUG1 overexpression. CONCLUSIONS: We found that overexpressed TUG1 stimulates proliferation and migration of endothelial cells via Wnt pathway, thereby promoting the occurrence and progression of diabetic atherosclerosis.

p38 Mitogen-activated protein kinases is required for counteraction of 2-methoxyestradiol to estradiol-stimulated cell proliferation and induction of apoptosis in ovarian carcinoma cells via phosphorylation Bcl-2.

INTRODUCTION: 2-Methoxyestradiol (2ME2), a natural endogenous product of estradiol (E2) metabolism, has been shown to be a selective apoptotic agent for cancer cells but not for normal cells. In this study, we determined that 2ME2 counteracts E2-stimulated cell growth and induces apoptosis in ovarian carcinoma cells. In addition, we demonstrate that 2ME2 induces apoptosis via p38 and phospho-Bcl2 pathway. METHODS: 2ME2 and/or E2 were administered to the OVCAR-3 (human ovarian cancer) cell line. Cell growth inhibition was analyzed by [3H] Thymidine incorporation assay and DNA fluorometric assay. Cell apoptosis was tested by DNA fragmentation analysis and FACS. The signaling pathway was determined by a series of biochemical assays. RESULTS: 2ME2 inhibited estradiol-stimulated cell growth and induced apoptosis in an ovarian carcinoma cell line. MAPK and p38, but not JNK, were found to be critical mediators in this process. Expression of a dominant negative mutant of p38 kinase or p38 specific inhibitor, SB 203580, almost completely blocked the process. Furthermore, Bcl-2 phosphorylation was required for 2ME2-induced effects. CONCLUSION: Our data suggest that 2ME2 inhibits E2-stimulated proliferation and induces apoptosis in ovarian carcinoma cells. Furthermore, activation of p38 and phosphorylation of Bcl-2 plays a critical role in the mechanism. 2ME2 therefore, may have a clinical application for the treatment of ovarian cancer.

Progesterone induces apoptosis and up-regulation of p53 expression in human ovarian carcinoma cell lines.

BACKGROUND: Progesterone (PROG) has been shown to reduce the risk of developing ovarian carcinoma in postmenopausal women who have undergone estrogen and progestogen replacement therapy, and it has been clinically used to treat some types of ovarian tumors. It is not yet clear whether or not the antitumor activity of progestogen is due to its ability to induce apoptosis in precarcinomatous and carcinomatous ovarian cells. The apoptosis-related genes p53, bcl-2, and c-myc have important roles in the regulation of programmed cell death, and thus may be involved in the process of the suspected PROG-induced apoptosis. METHODS: Antiproliferation effects of PROG on 3AO and AO ovarian carcinoma cells were determined by 3H-thymidine incorporation. Apoptosis of the PROG-treated cells was determined by DNA laddering analysis and was quantitated by both nuclear condensation and flow cytometry after cells were stained with propidium iodide. Cell cycle analysis was also performed by flow cytometry. The expression of p53, bcl-2, and c-myc after 72 hours of PROG treatment was detected by Northern blot analysis. RESULTS: In both 3AO and AO cell lines, cells proliferation was maximally inhibited by PROG after 72 hours of treatment at 10 microM concentration. Under the same conditions, more than 50% of PROG-treated cells had undergone apoptosis, whereas less than 3% of the cells were apoptotic in untreated cell cultures. After exposure to PROG for 72 hours, cells were arrested in the G1 phase of the cell cycle, and the levels of p53 mRNA were remarkably increased in both cell lines. No changes in expression of bcl-2 or c-myc were detected. CONCLUSIONS: PROG significantly inhibited cell proliferation and induced apoptosis in both of the ovarian carcinoma cell lines tested in this study. PROG treatment markedly up-regulated p53 expression in these cells, indicating involvement of p53 in PROG-induced apoptosis.