Effects of Matrine on Inhibition of Colon Cancer Cell DNA Damage Repair and Epithelial-Mesenchymal Transition by Targeting Checkpoint Kinase 1 Expression

Abstract

Background: Matrine, the main active ingredient in the traditional Chinese medical herb Sophora flavescens, has promising antitumor properties on tumor cell lines. However, the underlying molecular mechanisms remain to be clarified. This study explored the underlying molecular events for the anticancer effect of matrine, a plant alkaloid, on colon cancer cells in vitro and in vivo from the perspective of the DNA damage response. Methods: Colon cancer RKO (human colon cancer cells) cells were grown and transfected with checkpoint kinase 1 (CHK1) cDNA or vector-only, and then treated with or without matrine (0, 2, 4, or 8 µM) for transwell and comet assays, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), western blot, immunofluorescence experiments, enzyme-linked immunosorbent assay (ELISA), and subcutaneous tumorigenesis experiments of nude mice. Results: Matrine dose-dependently inhibited the cell migration and invasion capacity as well as induced DNA damage in RKO cells in vitro. In addition, matrine dose-dependently upregulated the expression of DNA single- and double-strand break marker proteins (γH2AX (γH2A histone family member X) and cleaved PARP1 (poly (ADP-ribose) polymerase 1)), DNA damage marker proteins, and E-cadherin;However, it downregulated the expression of vimentin and CHK1. Furthermore, compared with the matrine plus vector control group, CHK1 overexpression induced the cell migration and invasion abilities of RKO cells. CHK1 overexpression also reduced E-cadherin expression but induced vimentin expression in RKO cells. CHK1 overexpression suppressed the expression of the DNA damage-related proteins (γH2AX, cleaved PARP1, and PARP1) and E-cadherin but increased the expression of vimentin in RKO cells. Moreover, matrine could reduce the release of interleukin (IL)-1β and IL-8 in vivo, which compose the DNA damage secretory program (DDSP). In the subcutaneous tumorigenesis experiment of nude mice, it was confirmed by immunohistochemistry that CHK1 expression decreased and γH2AX expression increased after matrine treatment. Conclusions: Matrine was able to inhibit activation of the DNA damage response kinase CHK1, thereby inhibiting the DNA damage response and epithelial-mesenchymal transition (EMT) in colon cancer cells.