Pro-apoptotic and anticancer properties of Thapring – A Tibetan herbal formulation

Abstract

To evaluate the pro-apoptotic and anti-tumorigenic properties of Thapring - a Traditional Tibetan Medicine - in hepatoma cells and in a transgenic mouse model of hepatocellular carcinoma. The pro-apoptotic action and growth inhibition property of Thapring were assessed in Huh7, HepG2 and A549 cell lines using flow cytometry and MTT assay, respectively. Confocal microscopy for colocalization of cytochrome c and mitochondria was done using dsRed mitotracker in Huh7 cells. The activation of p38 MAP kinase and p53 pathway was evaluated by Western blotting. Serological studies for liver function, vascular endothelial growth factor and superoxide dismutase were assessed in the serum of X15-myc transgenic mice. Immuno-histochemical studies for Bcl2 and p21(Waf1) expression were also carried out in the liver section of the above mice. Treatment with Thapring inhibited proliferation and accumulation of hepatoma cells in G1 phase. There was increased cytochrome c release from mitochondria and decreased Bcl2 levels - the key markers of apoptotic cell death. Besides activation of p38 MAP kinase and increased p53 expression were also observed. Oral administration of Thapring in transgenic mice lowered serum VEGF levels and conferred hepatoprotection as evident from normal serum ALT levels. Further, immunohistochemical analysis of the liver samples revealed reduced expression of anti-apoptotic protein Bcl2 and over-expression of cell cycle regulator p21(Waf1). The ability of Thapring to impose growth arrest and trigger pro-apoptotic death in cell culture as well as ameliorative effects in vivo provides scientific basis for its usefulness as traditional medicine and its clinical application in adjunct/combination therapy along with other known anticancer drugs.