Overexpression of phosphoserine aminotransferase PSATI stimulates cell growth and increases chemoresistance of colon cancer cells

Background: Colorectal cancer (CRC) is one of the most common causes of cancer death throughout the world. In this work our aim was to study the role of the phosphoserine aminotransferase PSATI in colorectal cancer development. Results: We first observed that PSATI is overexpressed in colon tumors. In addition, we showed that after drug treatment, PSATI expression level in hepatic metastases increased in non responder and decreased in responder patients. In experiments using human cell lines, we showed that ectopic PSATI overexpression in colon carcinoma SW480 cell line resulted in an increase in its growth rate and survival. In addition, SW480-PSATI cells presented a higher tumorigenic potential than SW480 control cells in xenografted mice. Moreover, the SW480-PSATI cell line was more resistant to oxaliplatin treatment than the non-transfected SW480 cell line. This resistance resulted from a decrease in the apoptotic response and in the mitotic catastrophes induced by the drug treatment. Conclusion: These results show that an enzyme playing a role in the L-serine biosynthesis could be implicated in colon cancer progression and chemoresistance and indicate that PSATI represents a new interesting target for CRC therapy.