Molecular study of PIK3CA exon 20 and their role in PIK3CA expression in patients having colorectal carcinoma

Abstract

Colorectal carcinoma one of most incidence and dangerous cancer around the world. The aim of current study to investigate the association between any molecular aberration in PIK3CA gene, exon 20 and PIK protein expression in colorectal carcinoma development. Methods; The current study achieved in two lines, Molecular study which achieved in advanced researches laboratory in biology department, Faculty of Sciences / University of Kufa, while immunohistochemical study was achieved in histopathology department, faculty of Medicine / University of Kufa. Only Iraqi patients were included in the current study who diagnosed through period extend from 01 December 2019 to 30 February 2021 and any patients diagnosed before or after this period were excluded. Also any samples without case report were excluded. The present study included 103 cases divided into two groups, patients group were included 50 cases with colorectal carcinoma(adenocarcinoma) and 53 cases with other non-adenocarcinoma such as hyperplastic polyp and colitis. According to gender, a study was included 61 male and 42 female. According to patients ages. the average was(50-89) years. The samples were collected from AL-Sader medical city in AL-Najaf province and Medical city in Baghdad province. Blood samples and tissues samples were collected from each 103 patients after enter the hospital(s) and have report of colonoscopy or CT-scan. blood samples were used in molecular line to (DNA extraction and sequencing). Tissues sample were confirmed by H&E examination and from these 102 cases only 50 cases with and other cases were excluded from a study. Breast carcinoma used as positive control for PIK3CA. Results: 27 cases (54%) given positive for staining with PIK3CA antibodies, but with normal genotype in sequencing. Therefore, there was no any correlation between colorectal carcinoma development and any aberration in PIK3CA gene –Exon 20 in current study. According to relation between colorectal carcinoma grades and positive and negative for PIK3CA, 15 cases(44%) in grade I, 8 cases (67%) in grade II and 4 cases (100%) were given positive for PIK3CA. There is positive correlation between grades and both ages and positive and negative cases( P =0.173 and sig=0.229) (P 0.312, sig 0.027) respectively. while, Negative correlation found between gender with both age and grades (p= -0.304, sig= 0.032) (P -0.365, sig=0.009) respectively. Also the negative correlation found between positive or negative cases for PIK3CA with both age and gender (P -0.196, sig 0.172)(P -0.201, sig 0.162) respectively. Conclusion: Due to relation between molecular study of PIK3CA Exon 20 and IHC study of PIK3CA expression, we don't found any relation between PIK3CA expression in patients with colorectal carcinoma and genetic aberration in PIK3CA gene, exon 20. According to relation between PIK3CA score index and grades, increase in PIK3CA score index directly Proportional with advance in grade of colorectal carcinoma. According to grades and cases with positive or negative cases, found numbers of cases that give positive for PIK3CA Abs increase with advance in grades.., There is positive correlation between grades and both ages and positive and negative cases for PIK3CA. while, Negative correlation found between gender with both age and grades. Also the negative correlation found between positive or negative cases for PIK3CA with both age and gender.