Reduced Expression of RNA Binding Protein CELF2, a Putative Tumor Suppressor Gene in Colon Cancer

Background & aims: Colon cancer is the third leading cause of cancer death in both men and women in the United States. Every year, 160000 cases of colorectal cancer are diagnosed, and 57000 patients die. CUGBP, Elav-like family member 2 (CELF2) is an RNA binding protein that modulates various posttranscriptional events including RNA splicing, shuttling, editing, stability and translation. Previous studies have demonstrated that CELF2 expression is low in colon cancer cells. Furthermore, ectopic overexpression of CELF2 induces cells to undergo death by mitotic catastrophe. Based on the above observations, we hypothesized that CELF2 expression might be reduced during neoplastic transformation of colon cells.

Methods: Forty human colon cancer tissues along with 10 uninvolved normal colon tissues from cancer patients were utilized for immunohistochemical analysis of CELF2 expression.

Results: We have observed that CELF2 levels are reduced in colon tumor tissues when compared to the normal intestinal tissues. The data set suggests that RNA binding protein CELF2 could be a potential tumor suppressor protein. CELF2 was predominantly nuclear in normal cells, while the cancer tissues had diffused cytoplasmic staining.

Conclusion: CELF2 expression is consistently reduced during neoplastic transformation suggesting that it might play a crucial role in tumor initiation and progression.