Analysis of a Novel JK-1 Gene Expression in Benign and Malignant Colorectal Tumors

Abstract

Introduction: Colorectal tumors are amongst the most common neoplasms affecting individuals in industrialized nations. A newly discovered gene, JK-1 (FAM134B) located in chromosome 5 p15.2 plays an important role in molecular pathogenesis of esophageal cancer. This study aims at examining the role of this gene in colorectal tumors by analyzing the differences in gene mRNA expression in both benign and malignant colorectal tumors in comparison with non-neoplastic samples of colorectal tissue. Methods: The study was performed on 162 colorectal adenocarcinoma, 32 benign adenoma and 20 non-neoplastic colorectal tissues. mRNA was extracted from the prospectively collected tissues and converted into cDNA. Primers were designed for the JK-1 gene and gene expression levels were determined using real-time PCR. The expression levels were calculated as a ratio of the Ct value for JK-1 to GAPDH (housekeeping gene) and expressed as inverse ratio to reflect the changes in gene expression. Results: The JK1 mRNA was detected in all colorectal tissues. The mean inverse ratio for JK-1 gene in adenoma samples was 0.929 ᠰ.005 which was significantly higher than in non-tumor samples which was 0.901 ᠰ.009 (p=0.005). On the other hand, cancer samples had a mean inverse ratio of 0.875 ᠰ.006 which was significantly lower than in non-tumor tissues (p<0.001). Conclusions: The results of this study indicate that JK-1 expression has a role in the carcinogenesis in colorectal cancer. The under-expression of the gene in cancer suggests that loss of gene expression may promote tumor progression, that it may act as a tumor suppressor gene or that it relates to certain genetic events in tumor pathogenesis. However, over-expression of JK-1 in adenoma samples may indicate that JK-1 has a functional role in dysplastic benign colon tumors, a function that is disrupted once the tumor progresses to a more invasive form.