Inotodiol Inhabits Proliferation and Induces Apoptosis through Modulating Expression of cyclinE, p27, bcl-2, and bax in Human Cervical Cancer HeLa Cells

Abstract

Inonotus obliquus is a medicinal mushroom that has been used as an effective agent to treat various diseasessuch as diabetes, tuberculosis and cancer. Inotodiol, an included triterpenoid shows significant anti-tumor effect.However, the mechanisms have not been well documented. In this study, we aimed to explore the effect of inotodiolon proliferation and apoptosis in human cervical cancer HeLa cells and investigated the underlying molecularmechanisms. HeLa cells were treated with different concentrations of inotodiol. The MTT assay was used toevaluate cell proliferating ability, flow cytometry (FCM) was employed for cell cycle analysis and cell apoptosis,while expression of cyclinE, p27, bcl-2 and bax was detected by immunocytochemistry. Proliferation of HeLacells was inhibited by inotodiolin a dose-dependent manner at 24h (r=0.9999, p<0.01). A sub-G1 peak (apoptoticcells) of HeLa cells was detected after treatment and the apoptosis rate with the concentration and longerincubation time (r=1.0, p<0.01), while the percentage of cells in S phase and G2/M phase decreased significantly.Immunocytochemistry assay showed that the expression of cyclin E and bcl-2 in the treated cells significantlydecreased, while the expression of p27 and bax obviously increased, compared with the control group (p<0.05).The results of our research indicate that inotodiol isolated from Inonotus obliquus inhibited the proliferationof HeLa cells and induced apoptosis in vitro. The mechanisms may be related to promoting apoptosis throughincreasing the expression of bax and cutting bcl-2 and affecting the cell cycle by down-regulation the expressionof cyclin E and up-regulation of p27. The results further indicate the potential value of inotodiol for treatmentof human cervical cancer.