Altered mRNA expression levels of the major components of sphingolipid metabolism, ceramide synthases and their clinical implication in colorectal cancer

Ceramide synthases (CerSs) synthesize various ceramides of different acyl chain lengths and serve important roles in the proliferation and death of cancer cells by regulating sphingolipid metabolism-related signaling pathways. The present study investigated the mRNA expression levels of various CerS genes using mRNA expression data from six independent colorectal cancer (CRC) cohorts and a Korean CRC dataset. Expression levels of CERS2, CERS5 and CERS6 mRNA were significantly increased in the majority of the studied groups. However, CERS4 expression was only significantly altered in two groups. Additionally, a positive correlation was observed between altered CERS4 and CERS5 mRNA levels in The Cancer Genome Atlas Colon and Rectal Cancer dataset. Notably, CERS2 and CERS4, as well as CERS5 and CERS6 levels, were positively correlated with each other in Korean patients with CRC. However, the mRNA expression levels of these four CerS genes were not associated with any clinicopathological characteristics in Korean patients with CRC. Finally, overexpressing CERS2 or CERS6 inhibited the in vitro viability of various CRC cells. Taken together, these findings indicated that CERS2, CERS4, CERS5, and CERS6 are significantly dysregulated in CRC, suggesting they may serve important roles in the pathophysiology of this malignancy.