STUDY OF MUTATION IN EXON 7 OF AXIN 2 IN COLORECTAL CANCER (LABORATORY AND BIOINFORMATICS STUDIES)

Colorectal cancer is the third most common cancer in Iran. Wnt pathway changes
are commonly reported in this type of cancer. Some of the important activities of this pathway are the
role of carcinogenicity, cellular proliferation, cell migration, and so on. Axin2 acts as a negative
regulator in the Wnt / TCF signaling pathway and helps in the formation of the beta-catenin destruction
complex. Research has shown that this protein is mutated in many cases of CRC cancer. In past studies,
the mutation on the exon 7 of this gene is of particular importance because it is linked to PP2A
phosphatase and in various scientific sources; mutations in this region have been reported repeatedly in
colorectal tumors. The aim of this project is to study SNP with ID rs370618491 nucleotide C2140T in
exon 7 of axin 2 gene and to investigate the possible role of mutation in this SNP in colorectal cancer.
Materials & Methods: In this project, 147 frozen samples of patients (92 tumor tissues / 55 blood
samples) and 25 control samples, and 3 cell lines of colorectal cancer, HT29, SW480 and CACO-2 were
used. SNP selection was performed using bioinformatics methods including the use of NCBI, Ensembl
databases and polyphen tool; DNA extraction was done by phenol-chloroform method. The PCR-RFLP
method was used. The PCR-RFLP method was used and statistical analysis of demographic and clinical
data was done using SPSS software.
Results: This study showed that in one of 147 patient samples, there was a mutation in our preferred
SNP position; in other samples, including cell lines no mutation showed. The results of SPSS 16.0
showed that the incidence of colorectal cancer in men was 55.7% and the mean age of patients over 40
years was 74%. It was also found that the size of the tumor (T) with P = 0.016 and the degree of tumor
diffusion to the lymph nodes (N) with P=0.001 had a significant relationship with the grade of cancer
progression.
Conclusion: The presence one mutation in 147 samples indicates the low frequency of this SNP in the
Iranian population. Therefore, despite the importance of exon 7 in axin 2, laboratory results were not
consistent with the results of studies. Some factors can influence this outcome, including high variability
in factors affecting colorectal cancer and high genetic variation in Iranian population. In addition, it
usually comes from bioinformatics studies that provide information about the importance of an issue,
not its prevalence in a particular population; therefore, bioinformatics studies alone are not enough and
the frequency and clinical effects of a mutation in laboratory methods should also be considered. Due
to the importance of axin 2 in the Wnt pathway and the high rates of mutations observed in previous
studies, investigating the level of gene expression of axin 2 and the quality of its protein function can be
important in future studies