Trichosanthes kirilowii tuber extract induces G2/M phase arrest via inhibition of tubulin polymerization in HepG2 cells.

Unlabelled: Trichosanthes kirilowii tuber is one of most popular herbal plant of East Asia, which has been prescribed for patients with diabetes, rigorous coughing, breast abscesses, and cancer-related symptoms.

Aim Of The Study: To investigated the anticancer properties of the methanol extract of Trichosanthes kirilowii tuber (TKE), focusing on cell cycle arrest and microtubule instability in HepG2 cells.

Materials And Methods: Cell growth and death were checked using a CCK-8 assay and a LDH release assay respectively. Cell cycle was analyzed by FACS after PI staining. Immunofluorescence, Western blot, real-time PCR for tubulin were performed.

Results: TKE treatment inhibited cell growth at around 25 microg/mL of IC50 in a CCK-8 assay and a LDH release assay, but did not result in cell death. We found that TKE induced cell cycle arrest at the G2/M phase in a time-dependent manner. However, an immunofluorescence assessment of beta-tubulin revealed a dramatically reduced amount of polymerized tubulin after TKE treatment. Furthermore, TKE treatment radically decreased the polymerized portion of soluble tubulin in a dose-dependent manner, as did colchicine; the effects, however, were opposite to those of paclitaxel in comparative analysis of polymerized to soluble tubulin. We also found that TKE treatment moderately affected alpha-tubulin protein production, but not that of beta-tubulin and its gene expression using a Western assay and real-time PCR.

Conclusions: Anticancer mechanisms of TKE linked to the inhibition of tubulin polymerization, through which it exerts cell cycle arrest at the G2/M phase in the HepG2 cell line.