Positive correlation between expression level of mitochondrial serine hydroxymethyltransferase and breast cancer grade

Metabolic reprogramming plays an essential role in supporting the survival and proliferation of cancer cells. Serine hydroxymethyltransferase (SHMT) directs serine to the metabolism of one-carbon unit and the synthesis of thymidilate as a key factor in this metabolic shift. Although the mitochondrial isoform of SHMT (SHMT2) has been proven to be a crucial factor in the serine/glycine metabolism in several cancer cell types, the expression pattern of SHMT2 and the correlation of expression level of SHMT2 and other clinicopathological parameters in clinical breast cancer remain to be explored. In this research, 76 breast cancer patients who underwent modified radical mastectomy were enrolled for immunohistochemical analysis of the expression level of SHMT2 in their cancerous breast tissues for comparison with that in matching, distant noncancerous tissues. The results showed that SHMT2 was not expressed in the distant noncancerous cells. In contrast, SHMT2 protein could be stained in all breast cancer samples at varying degrees. Higher level of SHMT2 was expressed in grade III breast cancer cells than that those in grade I–II (P<0.05). In conclusion, SHMT2 was highly expressed in breast cancer cells, and the expression level of SHMT2 was positively correlated with breast cancer grade, suggesting that SHMT2 could be a target for anticancer therapies.