Cryptotanshinone increases the sensitivity of liver cancer to sorafenib by inhibiting the STAT3/Snail/epithelial mesenchymal transition pathway

Abstract Objective Sorafenib resistance has been a major factor limiting its clinical use as a targeted drug in liver cancer. The present study aimed to investigate whether cryptotanshinone can enhance the sensitivity of liver cancer and reduce the resistance to sorafenib. Methods Sorafenib-resistant cells were established based on HepG2 and Huh7 cell lines. And the anti-tumor effect of sorafenib combined with cryptotanshinone on the sorafenib-resistant cells was verified by MTT, colony formation, transwell assays and tumor growth xenograft model. Moreover, the effects of the combined treatment on the expression of phosphorylated (p)-STAT3, as well as epithelial mesenchymal transition (EMT) and apoptosis related proteins of cells were evaluated by western blot analysis. Results It was identified that cryptotanshinone inhibited the viability of both HepG2 and Huh7 cells in a dose- and time-dependent manner, and decreased p-STAT3 expression rather than total STAT3 expression at a concentration of 40 μmol/L. In the sorafenib-resistant cells, sorafenib in combination with cryptotanshinone markedly inhibited cell viability, invasion and migration compared with sorafenib alone. In contrast, increased p-STAT3 level by colivelin led to the inhibition of the synergistic effect of cryptotanshinone and sorafenib not only on cell viability, but also on EMT and apoptosis, suggesting that cryptotanshinone and sorafenib may act by downregulating STAT3 signaling. Further, the inhibition of carcinogenicity effect was also verified in xenografted tumor models. Conclusion The present results indicated that cryptotanshinone could synergize with sorafenib to inhibit the proliferative, invasive, and migratory abilities of sorafenib-resistant cells by downregulating STAT3 signaling.