Purpose: Colorectal cancer (CRC) is one of the most common types of malignancies, and radiochemotherapy (RCT) followed by surgery is the recommended approach for CRC treatment. However, some cases do not respond to first-line conventional chemotherapy or even progress further after treatment. Moreover, there is a risk of severe side effects, such as radiodermatitis. Therefore, identifying predictors for RCT sensitivity is an essential step toward predicting and eventually overcoming resistance.
Materials and Methods: We used integrative bioinformatics analysis and experimental validation to show that regenerating family member 4 (REG4 ) may be a potential biomarker for RCT sensitivity in CRC.
Results: REG4 , whose expression is upregulated in some CRC tissues and downregulated in RCT-sensitive CRC cells, was identified as a potential genetic marker for RCT sensitivity in CRC. Immunohistochemistry-based tissue microarray of human CRC was used to experimentally validate REG4  data obtained from the bioinformatics analysis.
Conclusion: Collectively, these results indicate that REG4  may be a potential biomarker for RCT sensitivity in CRC.
Keywords: radiochemotherapy resistance, regenerating family member 4, immunohistochemistry microarray, colon cancer transcriptome