Total flavonoid aglycones extract in Radix Scutellariae induces cross-regulation between autophagy and apoptosis in pancreatic cancer cells

Ethnopharmacological relevance: Radix Scutellariae (RS), the dried root of Scutellariae baicalensis Georgi, known as a herbal medicine in several Asian countries including China, has been widely used to treat inflammation, hypertension, cardiovascular disease as well as cancer. The total flavonoid aglycone extracted (TFAE) was extracted by ethyl acetate and this extraction methodology was optimized and obtained the protection of Chinese patents. Aim of the study: To investigate the underlying mechanism of the chemotherapeutic effects of TFAE in inducing autophagy and apoptosis in pancreatic cancer cells in vitro and in vivo. Materials and methods: We performed CCK8 assays, AnnexinV-FITC/PI staining, flow cytometry assays, transmission electron microscopy, immunofluorescence analysis and Western blot to study the molecular mechanism of TFAE in inducing autophagy and apoptosis in pancreatic cancer cells in vitro and in vivo. Results: In vitro, TFAE exhibits significant anti-tumor activity against pancreatic cancer cell lines, especially for BxPC3 (IC50 = 6.5 mu g mL(-1) ). Moreover, TFAE induces apoptosis and autophagy as evidenced by the increased apoptosis or autophagy-related protein level, the increased the fraction of apoptotic cells and the punctuate patterns of LC3 II. Furthermore, TFAE induce autophagy through PI3K/Akt/mTOR inhibition. Interestingly, pharmacological block autophagy by 3-MA enhanced TFAE-induced apoptosis, indicating that TFAE induced autophagy functions as a cytoprotective process against apoptosis. In vivo, 150 mg/kg TFAE inhibited the BxPC3 tumor growth in immune deficient mice with the inhibitory rate of 66.87% and induced both apoptosis and autophagy. Conclusion: TFAE have anti-tumor activity against pancreatic cancer and can induce apoptosis and autophagy through PI3K/Akt/mTOR signal pathway. TFAE might be a potential anticancer drug to be further developed for human pancreatic cancer therapy.