Polyphenol-rich fraction of Bergenia ligulata (Wall.) Engl. sensitizes colon and breast cancer metastasis in vivo: Evidence of cell-type specific mechanism

BackgroundColon and breast cancer are one of the leading causes of mortality worldwide. Limited efficacies of present treatments highlighted an urgent need for improvement. Bergenia ligulata is known for its anticancer properties in Indian traditional and folk medicine though the molecular basis of its effects, particularly its anti-metastatic properties, is not well understood. Anti-prostate cancer activity of a LCMS defined polyphenol-rich fraction from Bergenia ligulata (PFBL) rhizome extract has already been published showing promising results in preclinical models. PurposeThe present study aims to explore anti-cancer activity and anti-metastatic potentials of PFBL against colon and breast cancers in both in vitro and preclinical settings. Study design and methodsPFBL alone or in synergy with standard chemotherapeutic drugs was tasted in CT26 and 4T1 subcutaneous solid tumors in BALB/c mice. The effect of PFBL was analyzed in terms of changes in tumor mass and different molecular marker levels. Anti-metastatic potential of PFBL was evaluated in CT26 and 4T1 lung metastasis model in mice focusing on the number of lung nodules and lung size. ResultsOur results evidenced that PFBL efficiently regressed both CT26 and 4T1-induced solid tumors alone and in combination with 5FU/doxorubicin without affecting the health of normal host. Notably, PFBL suppressed lung metastasis of 4T1 and CT26 cells in mice with great efficacy. Analysis of tumor and cell extracts suggested that colon cancer cells died by autophagy, while breast cancer cells majorly died by caspase-dependent apoptosis. PFBL actions involved AMPK-dependent inhibition of mTORC1 and subsequent increase in LC3II, PARP1, CDK4 and Cyclin D1 levels in both HCT116 and MCF7 cells; an elevation of intracellular ROS level was the major cause of death in both the cancer types. PFBL treatment also reversed the EMT marker expressions in in vivo and in vitro. ConclusionPFBL regressed colon and breast cancer metastasis through distinct mechanisms with little effect on healthy mice. The present study underscored PFBL as a novel anti-tumor and anti-metastasis candidate warranting further testing in clinical settings.