Abstract
The chromosome segregation 1‑like (CSE1L) protein, which regulates cellular mitosis and apoptosis, was previously found to be overexpressed in colorectal cancer (CRC) cells harboring mutations. Therefore, regulating CSE1L expression may confer chemotherapeutic effects against CRC. The gut microflora can regulate gene expression in colonic cells. In particular, metabolites produced by the gut microflora, including the short‑chain fatty acid butyrate, have been shown to reduce CRC risk. Butyrates may exert antioncogenic potential in CRC cells by modulating p53 expression. The present study evaluated the association between CSE1L expression and butyrate treatment from two non‑transformed colon cell lines (CCD‑18Co and FHC) and six CRC cell lines (LS 174T, HCT116 p53+/+, HCT116 p53‑/‑, Caco‑2, SW480 and SW620). Lentiviral knockdown of CSE1L and p53, reverse transcription‑quantitative PCR (CSE1L, c‑Myc and p53), western blotting [CSE1L, p53, cyclin (CCN) A2, CCNB2 and CCND1], wound healing assay (cell migration), flow cytometry (cell cycle analysis) and immunofluorescence staining (CSE1L and tubulin) were adopted to verify the effects of butyrate on CSE1L‑expressing CRC cells. The butyrate‑producing gut bacteria Butyricicoccus pullicaecorum was administered to mice with 1,2‑dimethylhydrazine‑induced colon tumors before the measurement of CSE1L expression. The effects of B. pullicaecorum on CSE1L expression were then assessed by immunohistochemical staining for CSE1L and p53 in tissues from CRC‑bearing mice. Non‑cancerous colon cells with the R273H p53 mutation or CRC cells haboring p53 mutations were found to exhibit significantly higher CSE1L expression levels. CSE1L knockdown in HCT116 p53‑/‑ cells resulted in G1‑and G2/M‑phase cell cycle arrest. Furthermore, in HCT116 p53‑/‑ cells, CSE1L expression was already high at interphase, increased at prophase, peaked during metaphase before declining at cytokinesis but remained relatively high compared with that in HCT116 expressing wild‑type p53. Significantly decreased expression levels of CSE1L were also observed in HCT116 p53‑/‑ cells that were treated with butyrate for 24 h. In addition, the migration of HCT116 p53‑/‑ cells was significantly decreased after CSE1L knockdown or butyrate treatment. Tumors with more intense nuclear p53 staining and weaker CSE1L staining were found in mice bearing DMH/DSS‑induced CRC that were administered with B. pullicaecorum. Taken together, the results indicated that butyrate can impair CSE1L‑induced tumorigenic potential. In conclusion, butyrate‑producing microbes, such as B. pullicaecorum, may reverse the genetic distortion caused by p53 mutations in CRC by regulating CSE1L expression levels.