Clinicopathologic significance of serum response factor expression in colorectal adenocarcinomas

Background and aim: The purpose of this study was to investigate the role of serum response factor (SRF) expression and to evaluate its correlation with various clinicopathological parameters in colorectal adenocarcinomas. Methods: We used tissue microarrays consisting of 24 normal mucosa, 50 tubular adenomas, 496 adenocarcinomas, and 128 metastatic lesions. Results: The expression of SRF was rare in normal colonic mucosa with a mean expression score of 0.67 ± 0.17. Tubular adenomas had a mean expression score of 2.48 ± 0.31, adenocarcinomas 2.82 ± 0.13 and lymph node metastases 2.82 ± 0.36. Interestingly, SRF expression was high in distant metastases with a mean expression score of 4.83 ± 0.43. The mean SRF expression was increased significantly early in the normal-adenoma-carcinoma sequence and again in distant metastases. The positive SRF expression was strongly correlated with non-mucinous tumor type (P < 0.001). Moderately and poorly differentiated adenocarcinomas had higher mean expression scores than well-differentiated adenocarcinomas (2.88 ± 0.13 vs 1.33 ± 0.32) (P= 0.015). There were significant associations between SRF expression and expression of p53 (P= 0.034) and Ki-67 (P= 0.001). Conclusions: Our results suggest that SRF expression may be the early event of normal-adenoma-carcinoma sequence of colorectal cancer, especially in adenomatous change of colonic mucosa and may play an important role in distant metastasis of colorectal cancers.