Functional assessment of a novel mutation (SMAD4, p. Cys115Arg) in a Palestinian patient with Colorectal cancer رسالة ماجستير

Abstract

Colorectal carcinoma (CRC) is a globally common cancer that leads to mortality and morbidity. Genetic testing is becoming an essential tool for colorectal cancer (CRC) diagnosis and treatment pathway. In a variety of colorectal tumors, SMAD4 is somatically inactivated. Moreover, it was shown that expression loss of SMAD4 is correlated with both; metastatic development, a poor response to chemotherapy, and decreased immune infiltrate, reinforcing its use as a prognostic marker for CRC patients. In this study, Next-Generation Sequencing (NGS) was utilized to identify genetic variants that contribute to the tumorigenesis of colorectal cancer. Our analysis identified the following variants: (NOTCH1, p.Asp1533Gly), (EGFR, p.Leu619Pro), (MAP2K1, p.Pro265Ser), (ALK, p.Phe174Leu), (ERBB2, p.Asp1252His), (FBXW7, p.Gly477Arg), (FGFR2, p.Met538Ile), (GNA11, p.Leu170Phe), (MET, p.Asp153Asn), (NOTCH1, p.Ala1610Thr), (PIK3CA, p.Asn107Thr), (SMAD4, p.Cys115Arg). In silico analysis of the previously mentioned variants presumed (SMAD4, p.Cys115Arg) as a highly likely pathogenic variant. To further investigate the function of the identified variant, luciferase assay was used to assess the effect of the mutation on SMAD4 gene transcriptional activity. Our results revealed that the mutation decreased SMAD4 transcriptional activity by four fold compared to the wild-type SMAD4. This research provides a better understanding of the cancer genetic landscape in Palestine by characterizing the functional effects of (SMAD4, p. Cys115Arg). Moreover, it might contribute to developing personalized and targeted therapies and treatments for those diagnosed with CRC