Loss of SATB2 and CDX2 Expression is Associated with DNA Mismatch Repair Protein Deficiency and BRAF Mutation in Colorectal Cancer

The relationship between the expression of the SATB2, CDX2, and p53 proteins and common molecular changes in colorectal cancer (CRC) has rarely been studied. Recent literature suggests that the loss of SATB2 and CDX2 expression is more frequently observed in cases of colon cancer with DNA mismatch repair (MMR) protein deficiency and BRAF mutation. We collected 1180 cases of CRC and explored the association between the expression of SATB2, CDX2, and p53 and clinicopathological characteristics and molecular alterations of CRC using whole-slide immunohistochemistry. Our results showed that negative expression of SATB2 and CDX2 was more common in MMR-protein-deficient CRC than in MMR-protein-proficient CRC (15.8% vs. 6.0%, P = 0.001; 14.5% vs. 4.0%, P = 0.000, respectively). Negative expression of SATB2 and CDX2 was more common in BRAF-mutant CRC than in BRAF wild-type CRC (17.2% vs. 6.1%, P = 0.003; 13.8% vs. 4. 2%; P = 0.004, respectively). There was no relationship between SATB2 and/or CDX2 negative expression and KRAS, NRAS, and PIK3CA mutations. The expression of p53 was not associated with MMR protein status or BRAF, KRAS, NRAS and PIK3CA mutations. In addition, the lack of expression of SATB2, CDX2, and p53 was associated with poor histopathological features of CRC. In conclusion, the lack of SATB2 and CDX2 expression in CRC was associated with MMR protein deficiency and BRAF mutation, but not with KRAS, NRAS and PIK3CA mutation. The expression of p53 protein was not related to the common molecular changes of CRC.