The combination of
chemotherapy with natural products is a common strategy to enhance anticancer effects while alleviating the dose-dependent adverse effects of
cancer treatment.
Oxymatrine (OMT) has been extensively reported as having anticancer activity.
Doxorubicin (DOX) is a chemotherapeutic
DNA-damaging agent used for the treatment of
carcinoma. In this study, we investigated whether synergistic effects exist with the combination treatment with OMT and DOX using human
colorectal cancer cell (CRC) lines and the potential mechanisms involved in in vitro and in vivo activities. The MTT and colony formation assay results showed that compared to either OMT or DOX monotherapy, the combination of OMT + DOX markedly inhibited the growth of HT-29 and SW620 cells. Wound healing assays showed significant inhibition of cell migration with co-treatment, supported by the change in
E-cadherin and
N-cadherin expressions in Western blotting. Furthermore, flow cytometry analysis revealed that OMT + DOX co-treatment enhanced cell apoptosis as a result of ROS generation, whereas NAC attenuated OMT + DOX-induced apoptosis. Similarly, the apoptosis-related
proteins (cleaved
caspase-3, cleaved
caspase-9, and the ratio of Bax/Bcl-2) were determined by Western blotting, which showed that the expressions of these markers were notably increased in the co-treatment group. Furthermore, co-administration of a low dose of DOX and OMT inhibited xenograft
tumor growth in a dose-dependent manner. TUNEL assay and Ki67 staining images indicated more apoptosis and less proliferation occurred in OMT plus DOX-treated xenograft
tumors. Meanwhile, the combination strategy decreased
cardiotoxicity, which is the most serious side effect of DOX.
RNA sequencing was performed to explore the precise molecular alterations involved in the combination group. Among the numerous differentially expressed genes, downregulated FHL-2 and upregulated cleaved SPTAN1 were validated in both
mRNA and
protein levels of HT-29 and SW620 cells. These two
proteins might play a pivotal role involving in OMT + DOX synergistic activity. Overall, OMT in combination with DOX presented an outstanding synergistic antitumor effect, indicating that this beneficial combination may offer a potential
therapy for CRC patients.