Traditional Chinese medicine formula T33 inhibits the proliferation of human colorectal cancer cells by inducing autophagy.

Colorectal cancer (CRC) is a leading cause of cancer-related death globally. Although surgery is still the major method for CRC therapy, the adoption of alternative treatments, such as traditional Chinese medicine (TCM), for CRC treatment is increasing. Our previous study has indicated the anti-breast cancer activity of T33 (a TCM formula). Interestingly, a major ingredient in T33, Baishao (Paeoniae Radix Alba), was reported to have antiproliferative effects on CRC cells. Therefore, this study further validated the influences of T33 on HT-29 and Caco2 cells both in vitro and in vivo. Viability and migration assays were performed to analyze the influences of T33 on proliferation and migratory activity of HT-29 and Caco2 cells. Immunofluorescence (IF) staining and immunoblotting were performed to confirm T33-induced autophagy in HT-29 and Caco2 cells. Xenograft HT-29 tumors were generated to test the effects of T33 in vivo. Significantly reduced survival and migratory activity were observed in both HT-29 and Caco2 cells treated with T33 along with apparently increased LC3-II protein. Significantly decreased p62/SQSTM1 protein, increased LC3-II/LC3-I ratio, and elevated amounts of Atg7, Atg5, and Beclin-1 proteins were detected in both HT-29 and Caco2 cells treated with T33. Moreover, the volume of xenograft HT-29 tumors was significantly lower in mice receiving 200 or 600 mg/kg T33 than in control-treated mice. These findings indicate that T33 exerts anti-CRC activity by inducing autophagy and suggest the potential of T33 for CRC treatment.