Nifedipine induced autophagy through Beclinl and mTOR pathway in endometrial carcinoma cells

Background Endometrial carcinoma is one of the most common female tract genital malignant tumors. Nifedipine, an L-type calcium channel antagonist can inhibit cell proliferation of carcinomas. Recent studies indicated that a rise in the free cytosolic calcium （[Ca2±]c） was a potent inducer of autophagy. Here, we investigated the relationship between nifedipine and autophagy in Hec-IA cells. Methods Cells were cultured with nifedipine （10 μmol/L） and harvested at different times for counting cell number. MTT assay was applied to evaluate the cell viability and transwell assay to reveal cell migration. Apoptotic cells were detected with annexin V/PI assay. Then cells were treated with 3-methyladenine （3-MA） （2.5 mmol/L） for 0, 5, 15, 30, 60, and 120 minutes and the expression of the L-type calcium channel alphalD （Cavl.3） protein was detected. At last, cells were cultured and assigned to four groups with different treatment： untreated （control group）, 10 μmol/L nifedipine （N group）, 2.5 mmol/L 3-MA （3-MA group）, and 10 μmol/L nifedipine plus 2.5 mmol/L 3-MA （N±3MA group）. Autophagy was detected with GFP-LC3 modulation by fluorescent microscopy, and expression of the autophagy-associated proteins （LC3, Beclinl and P70s6K） by Western blotting and monodansylcadaverine （MDC） labeled visualization. Results Proliferation of Hec-lA cells was obviously suppressed by nifedipine compared with that of the untreated cells for 24, 48, and 96 hours （P=0.000 for each day）. The suppression of migration ability of the nifedipine-treated cells （94.0±8.2） was significantly different from that of the untreated cells （160.00±9.50, P=0.021 ）. The level of early period cell apoptosis induced by nifedipine was （2.21_±0.19）%, which was （2.90±0.13）% in control group （P=-0.052）, whereas the late period apoptosis level reached （10.38_±0.96）% and （4.40_±0.60）% （P=0.020）, respectively. The 3-MA group induced a slight increase in the Cavl.3 levels within 15 minutes, but significantly attenuated the Cavl.3 levels after 30 minutes. There were more autophagic vacuoles labeled by MDC in the N group （20.63_±3.36） than the control group （6.29_±0.16, P=-0.015）. GFP-LC3 localization revealed that the LC3 levels of cells in 3-MA group, N±3MA group, 3-MA group were 2.80_±0.29, 2.30_±0.17, and 1.80±0.21, respectively. Cells in the N group showed significant augmentation of autophagy （P 〈0.05）. Western blotting analysis confirmed the down-regulation of LC3 levels in 3-MA group （0.85±0.21） and N±3MA g