Leptin stimulation of cell cycle and inhibition of apoptosis gene and protein expression in OVCAR-3 ovarian cancer cells

Abstract

The OVCAR-3 cell line expressing the long (ObRb) and short (ObRt) isoforms of leptin receptor mRNA was used to analyze the effect of leptin on the expression of selected genes and proteins involved in the cell cycle and apoptosis. OVCAR-3 cells were exposed to 2, 20, 40, and 100 ng/ml of leptin. Cell proliferation was determined using the alamarBlue cell viability test and flow cytometry. Apoptosis was measured using a cellular DNA fragmentation ELISA kit. The expression of selected cell cycle and apoptosis genes was evaluated by real-time PCR and confirmed by western blot. The stimulatory action of leptin on cell proliferation was observed as an increase in cells in the S and G2/M phases. Up-regulation of genes responsible for inducing cell proliferation and suppression of genes responsible for inhibition of proliferation were noted. Western blots revealed increased expression of cyclins D and A and inhibition of p21WAF1/CIP1 protein expression by leptin. Inhibition of DNA fragmentation was observed under all leptin doses. Suppression of genes involved in the extrinsic and intrinsic apoptotic pathway was observed. Western blots illustrated decreased Bad, TNFR1, and caspase 6 protein expression in response to leptin treatment. Leptin promotes ovarian cancer cell line growth by up-regulating genes and proteins responsible for inducing cell proliferation as well as down-regulating pro-apoptotic genes and proteins in apoptotic pathways. Results of this study warrant examining the relationship between the risk of ovarian cancer and elevated leptin levels in obese women.

Leptin exerts proliferative and anti-apoptotic effects on goose granulosa cells through the PI3K/Akt/mTOR signaling pathway

“…In human breast cancer ZR-75-1 cells, the proliferative action of leptin was found to be associated with up-regulation of cyclin D1 and down-regulation of p21 [17], and there is evidence that leptin promotes human endometrial cancer proliferation by enhancing cyclin D1 expression together with inhibition of p21 [44]. The effects of leptin on stimulation of cell cycle and inhibition of apoptosis have also been shown in OVCAR-3 ovarian cancer cells which may be attributed to elevated levels of proliferative-related genes and decreased levels of pro-apoptotic-related genes [45]. Leptin is also considered as a proliferative factor for rat aortic smooth muscle cells [46], human hemopoietic cells [47] and colonic epithelial cells [15], as well as an anti-apoptotic factor for DU145 and PC-3 prostate cancer cell lines to enhance prostate cancer growth [14].…”

Association of Leptin Receptor Lys109Arg and Gln223Arg Polymorphisms with Increased Risk of Clear Cell Renal Cell Carcinoma

“…Leptin also is an important tumor cell growth factor. Several studies have demonstrated that leptin stimulates endothelial cell proliferation and angiogenesis, inhibits apoptosis gene and protein expression in cell lines (Samuel-Mendelsohn et al, 2011;Ptak et al, 2013;Wu et al, 2013;Yuan et al, 2013). Leptin exerts its biological functions through binding to the extracellular domain of LEPR.…”

Leptin, Cell Cycle, and Cancer

“…In an ovarian cancer study that used leptin receptor-expressing OVCAR-3 ovarian cancer cells, leptin was found to stimulate proliferation by upregulating cell cycle progression genes and suppressing cell cycle inhibitor genes. The authors also reported that leptin promoted cell cycle progression, as demonstrated by an increased cell population in both the S and G2/M phases [ 74 ]. In a separate study that used a mouse model of spontaneous thyroid cancer, consumption of a high-fat diet resulted in the development of obesity and elevated serum leptin levels.…”