Abstract
The well-known traditional Chinese medicine formula Pien Tze Huang (PZH) has long been used to treat various malignancies, including colorectal cancer (CRC). It was recently reported that PZH possesses the ability to overcome multidrug resistance in CRC cells. In the present study, a 5-fluorouracil (5-FU) resistant human CRC cell line (HCT-8/5-FU) was used to further evaluate the effect of PZH on chemotherapy (chemo)-resistance and investigate the mechanisms through which this occurs. The results identified that PZH significantly reduced the viability and cell density of HCT-8/5-FU cells in a dose- and time-dependent manner (P<0.05). PZH inhibited cell survival, reduced the proportion of cells in S-phase, and suppressed the expression of pro-proliferative proteins cyclin D1 and cyclin-dependent kinase 4. In addition, PZH treatment induced nuclear condensation and fragmentation, activated caspase-9 and -3 and increased the pro-apoptotic Bcl-2-associated X protein/B-cell lymphoma 2 protein ratio. Furthermore, PZH treatment upregulated the expression of microRNA-22 (miR-22) and downregulated the expression of c-Myc (a target gene of miR-22). In conclusion, the findings from the present study suggest that PZH can overcome chemo-resistance in cancer cells, likely through increasing miR-22 expression, and by reversing the imbalance between levels of proliferation and apoptosis.