ABSTRACT
Objective To investigate the effects of bamboo leaf extract on the malignant growth of human breast cancer MCF-7 cells under hypoxic microenvironment and the molecular mechanism .Methods Cultured human breast cancer MCF-7 cells were randomized into six groups :control group , hypoxia group ,0 .2 μg/mL bamboo leaf extract group ,0 .4μg/mL bamboo leaf extract group ,0 .8μg/mL bamboo leaf extract group and 0 .8μg/mL bamboo leaf extract group treated with IGF-1 .The cell proliferation activity in each group was determined using cell counting Kit-8 (CCK-8) assay .The expressions of proliferation markers PCNA ,Ki-67 and CCK-8 MCM2 in MCF-7 cells were detected by RT-PCR and Western blot .Flow cytometer was used to analyze the cell cycle arrest and cell apoptosis .The protein expressions of Bax ,Bcl-2 ,caspase-3 and survivin were measured by Western blot . Furthermore ,the effect of Akt/HIF-1αpathway underlying bamboo leaf extract-mediated inhibition on cancer cell growth was also explored .Results After treatment with bamboo leaf extract ,cell proliferation activity and the expressions of PCNA ,Ki-67 and MCM2 under hypoxia were obviously inhibited in a dose-dependent manner ( P<0 .01) . The proportion of MCF-7 cells upon hypoxia in the G2/M phase of the cell cycle was increased after treatment with bamboo leaf extract (P<0 .01) .The apoptosis rate of MCF-7 cells was enhanced after bamboo leaf extract stimulation ,accompanied with an increased protein levels of Bax and caspase-3 ,and decreased expressions of Bcl-2 and survivin (both P< 0 .01) .Moreover ,bamboo leaf extract down-regulated the expressions of p-Akt and HIF-1αin MCF-7 cells under hypoxia .IGF-1 ,an Akt/HIF-1α pathway agonist ,reversed the inhibiting effect of bamboo leaf extract on the malignant growth of MCF-7 cells under hypoxia .Conclusion Bamboo leaf extract inhibits the malignant growth of human breast cancer MCF-7 cells by suppressing the Akt/HIF-1αsignaling pathway under hypoxic microenvironment .