Diversin upregulates the proliferative ability of colorectal cancer by inducing cell cycle proteins

Colorectal cancer (CRC) is a common gastrointestinal tumour with increasing incidence worldwide. However, the underlying molecular mechanism of CRC proliferation is not completely clear. Diversin，as an ankyrin repeat-containing protein, is upregulated in various solid tumours and accelerates cancer progression by promoting cell proliferation and increasing S phase fraction of cells. In this study, 71 CRC samples and corresponding adjacent tissue samples were included. The expression of diversin in tissues was verified via immunohistochemical analysis. The MTS assay and flow cytometry (FCM) was used to measure cell proliferation and cell cycle. Results of immunohistochemical analysis revealed that diversin was highly expressed in human CRC tissues and was significantly associated with tumour differentiation, clinical stage and lymph node metastasis. The analysis based on the CRC data from The Cancer Genome Atlas (TCGA) database showed that a high expression of diversin correlated with the poor prognosis of CRC. Results of the MTS assay indicated that the overexpression of diversin promoted the proliferation of CRC cells, while its downregulation had an inhibitory effect on CRC cell proliferation. FCM analysises presented that diversin increased the flux of the CRC cell cycle from G1 to S and regulated cycle-related proteins, namely, P21, P27, cyclin E, CDK2, cyclin D and CDK4. The results suggest that diversin contributes to CRC proliferation that involves the distribution of the cell cycle. In CRC tissues, the expression of diversin has closely related to the prognosis. The higher the expression levels of diversin, the worse the prognosis. In vitro, diversin could increase the proliferative ability of CRC cells through the G1–S checkpoint and JNK signalling pathway, confirming that diversin contributes to CRC development.