During inflammatory responses, ICAM-1 expressed on the surface of endothelial cells associated with Mac-1 and LFA-1 on leukocytes invading tissues damaged by immune cells [Yang L. et al., 2005]. Two single nucleotide polymorphisms have been described in exons encoding the extracellular domains of the ICAM-1 gene. The first polymorphism encodes exon 4 at the + 241 position of glycine arginine (G241R), the second polymorphism is encoded by exon 6 at position +469, which changes glutamic acid to lysine (E469K) [Vora D K, et al., 1994]. As ICAM-1 involved in the immune response, it also plays a role in the prognosis of tumors and the development of cancers [Basoglu M. et al., 2007; Dowlati A. et al., 2008]. Tumor cells may lack ICAM-1 or LFA-3. They can also express mucin releasing in such a way as to contact immunocompetent cells. In addition, studies show that tumor cells are able to adapt to immune defense. In particular, lysis-resistant cells may be little accepted in tumor cells [Bodey B. et al., 2000]. These cells are capable of overexpression of Bcl-2, an anti-apoptotic gene. Immunosuppression, replenished with screening mechanisms that can settle in cancer patients with tumor development. The mechanisms of protection from tumor cells remain a nightmare for immunologists. It should be said that the context is not that of a great (success story) of immunology that has been vaccinated against infectious diseases [Banchereau J. et al., 2001]. ICAM-1 is expressed on several types of cancer cells and is also present at high levels in soluble form circulating in plasma from cancer patients [Choi Y L. et al., 2004; Hemmerlein B. et al., 2000; Lin Y C. et al., 2006 Tempia A A. et al.,2002]. It has also been suggested that ICAM-1 facilitates the spread of metastatic cancer cells to secondary foci so it may be involved in the metastatic process of cancers [Brooks K J; Liang S. et al., 2008; Wang S. et al., 2006]. The aim of our work is to compare the allelic and genotypic frequencies between healthy donors and patients with colon cancer.
Material and methods
We analyzed 55 peripheric blood samples from healthy donors and 56 peripheric blood samples from patients with colon cancer, this analysis was done at the Center for Molecular Biology and Biomedicine at Nizhny Novgorod State University. NI Lobachevski. The genomic DNA was isolated by phenol-chloroform extraction, rs5498 of the gene ICAM-1 was detected by polymerase chain reaction. The genotypes (A / G) of rs5498 SNP were detected after 1.5% electrophoresis and identified as rs5498 AA or homozygous GG, or heterozygous AG. Allelic variants of polymorphic genes underwent a classical molecular analysis — comparison of the occurrence of alleles and genotypes in patients with colon cancer and controls. The statistical analysis used was the x2 test for the difference analysis between the expected and observed frequencies, if P <0.05 the test is considered statistically significant. To determine the risk of disease, the odds ratio was calculated with a 95% confidence interval (95% C.I. — Confedence Interval).
Results and discussion
The results obtained in the two cases show that the genotypic distribution was significantly different with p <0.05. The genotypic and allelic distribution of ICAM-1 in healthy donors was: (54.5%) 30 donors had AA (homozygous), (38.2%) 21 donors had AG (heterozygous), and (7.3%) 4 donors had GG (homozygous). In patients with colon cancer the result was as follows (23.2%) 13 patients had AA (homozygous), (67.9%) 38 patients had AG (heterozygous), and (8.9%) 5 patients had GG (homozygous). The AG genomic frequency in patients was higher than in donors (67.9% vs 38.2%, χ2 = 11.72, P = 0.003). The comparison between the two shows us that people had an AG genotype with a high risk of colon cancer compared to people with the AA genotype. There was a higher expression of the ICAM-1 gene in patients with colon cancer (p = 0.0023). We performed this study in a population of Nizhny Novgorod, we noticed that the genetic polymorphism rs5498 SNP (A / G) of ICAM-1 is associated with a risk of colon cancer development. Genetic and allelic variants of ICAM-1 can be considered as predictors of colon cancer [Novikov V V. et al., 2016]
Intensive oncology research remains on the role of ICAM-1 and its relationship to malignancy of cancers, we believe it is important to determine the polymorphism of ICAM-1 in patients with colon cancer, because the ICAM-1 molecule is considered a diagnostic factor for colon carcinoma. So, it is estimated as a prognostic risk factor for colon cancer.