Orlistat treatment induces apoptosis and arrests cell cycle in HSC-3 oral cancer cells

The present study was aimed to investigate the effect of orlistat on an oral squamous cancer line HSC-3 as well as the underlying mechanism. Cell Counting Kit-8 (CCK-8) (Dojindo, Shanghai, China) was used for the analysis of proliferation, Annexin V-FITC and propidium iodide staining for apoptosis and flow cytometry for cell cycle distribution. Western blot assay was used to determine the alteration in the expression of cyclin D1, B1, E and CDK1. The results revealed a concentration and time-dependent decrease in the proliferation of HSC-3 cells by orlistat. The viability of HSC-3 cells was reduced to 23.4 ± 2.5 and 15.7 ± 1.6% at 40 and 50 μM concentration of orlistat after 48 h. Treatment of HSC-3 cells with orlistat resulted induction of apoptosis significantly (p < 0.05). Orlistat treatment led to the increase in proportion of apoptotic cells to 38.6 ± 2.5% after 48 h compared to 0.85 ± 0.34% in the control. Analysis of cell cycle showed that population of cells in G2/M phase in the cultures treated with orlistat for 48 h increased to 59.7 ± 5% compared to 10.2 ± 1.2% in the control. However, the population of cells in the G0/G1 and S phases was subsequently decreased. The expression of cyclin D1 and E was decreased and phosphorylation of CDK1 was increased by orlistat treatment in HSC-3 cells. Thus, orlistat induces apoptosis and cell cycle arrest in G2/M phase in HSC-3 cells through decrease in expression of cyclin D1 and E and increase in phosphorylation of CDK1. Therefore, orlistat can be used for the treatment of oral squamous cancer.