Calsyntenin 1 mRNA expression sensitivity to ionizing radiation in human hepatocytes and carcinoma cells and blood cells of BALB/c mice

Whether calsyntenin 1 (CLSTN1) and serine hydroxymethyltransferase 2 (SHMT2) are sensitive to low-dose ionizing radiation (LDIR) has not yet been defined. Therefore, here, we aimed to investigate changes in gene expression in hepatic cell lines and in blood cells and serum from irradiated mice. Levels of SHMT2 and CLSTN1 were decreased in cancer (HepG2) and normal (HH) hepatocytes exposed to various radiation doses. The mRNA expression of SHMT2 and CLSTN1 was altered in response to 0.5 or 4 Gy of radiation at 24 h post irradiation in vivo. However, plasma SHMT2 protein levels did not change at either radiation dose relative to those in the non-irradiated group. Plasma CLSTN1 protein levels notably decreased in response to 4 Gy of radiation but were not altered in response to 0.5 Gy of radiation. Thus, our findings suggest that the mRNA and protein levels of CLSTN1 might be useful biomarkers for radiation exposure. Further studies are needed to characterize the molecular regulation and functional roles of SHMT2 and CLSTN1 in response to radiation.