The Study of intron 4 of p53 gene in gastric cancer

Gastric cancer is one of the most prevalent cancers in the world and Iran. P53 is a tumor suppressor protein that its function is lost in most human cancers. Inactivation of P53 may be not only due to a mutation or deletion of TP53 gene, but also due to abnormal expression of isoforms of this gene. Δ133p53 isoform plays the role of anti-apoptotic by inhibition of P21 and miR-34, it is expressed of a conserved promoter that located in intron 4. Overexpression of Δ133p53 isoform have been reported in a number of human cancers, such as gastric cancer. Identify possible mutations in the sequence of intron 4 can offer a new perspective on the process of tumorigenesis. This study was performed on 48 patients with gastric cancer who had referred to Imam Khomeini hospital in Ardabil. Tumor and control tissues isolated via endoscopy and genomic DNA of tissues was extracted and then, to determine the possible mutation was sequenced. Finally, tumor samples sequence compared with normal tissues sequence from the same individual. The results of sequencing showed that there is a G to C transversion mutation at the 127 position of intron 4 in 27.3% of tumor samples and C to G transversion mutation at the 134 position of intron 4 in 18.2% of tumor samples. The most common site of tumor in this study was cardia and the average age obtained 67.4 years for males and 65.2 years for females. These results show that intron 4 mutations of p53 gene can be used as a molecular marker when a person has a P53 with wild type.