Association Of LMP Gene+3152C/T And Rs2071543SNP Loci Polymorphisms With The Chinese Sporadic Colorectal Cancer And Forensic Significance

IntroductionColorectal Cancer is one of the most common malignant tumors in China, with the economic development and lifestyle changes, the incidence rate increased year by year, and rose fast, the incidence rate is different in different geographic regions,ethnics and races.Disscusing the risk of having colorectal cancer and screening the high-risk groups are the current focuses of the prevention study of colorectal cancer.Single nucleotide polymorphisms (SNP) is the most common genetic variant form in human genome, which also is the third genetic markers after STR, their wide distribution, high density and genetic stability characteristics make them have important significance and practical application value in the human genetics,immunology, clinical study and forensic paternity testing and personal identification and other aspects.Human low molecular weight proteasome (LMP) gene is located in 6p21.3. including the LMP2 and LMP7 loci, both's introns and exons have SNPs. the most current researches is about exon single nucleotide polymorphisms, which are due to a single base mismatch, replacement and deletion, resulting in amino acid changes and thereby affecting protein expression and function.As is studied, LMP gene polymorphisms are closely associated with various immune-related diseases, viral infectious diseases, cancer and other diseases,having a genetic susceptibility.LMP is related closely with endogenous antigens processing and presenting. After endogenous antigens go to the body, they can be processed into peptides suitable to bind with MHC-I molecules (amino acid sequence is not clear). These polypeptides are transported to the endoplasmic reticulum cavity by the transporter associated with antigen processing(TAP), and then in the Golgi apparatus, they form stability HLA-Ag complex before it can be expressed on the cell surface and presented to T cells. Therefore, LMP is an important condition for a correct expression on cell surface of MHC-I class I molecules. Furthermore, the LMP2 and LMP7 different forms may lead to changes in the characteristics of protease hydrolysis, so it may affect the efficiency of antigen processing and the peptide spectrum.Because these changes stimulate the body's immune response, induce different immune processes, detecting LMP gene polymorphisms has great significance on the occurrence and development of certain tumors.However, there is no study about the relationship between LMP gene and colorectal cancer.In this study, we selected two SNPs sites which are the LMP2 gene +3152C/T and LMP7gene rs2071543 to investigate their polymorphisms in northern Han population guang xi zhuang zu population and colorectal cancer cases,and analyze whether there are differences beween dirrerent peoples and the relation of LMP gene SNPs with colorectal cancer. The intention is to provide valuable reference data for human genetics, immunology,clinical medicine and forensic areas.Materials and methods1.the samples used in this study is 400 heathy controls of the northern Han population,126 Han cases of colorectal cancer patients,160 healthy and unrelated individuals of guangxi Zhuang population.2.Genomic DNA extraction was performed, the according to the target sequence to design primers,PCR restriction fragment length polymorphism(PCR-RFLP) method, polyacrylamide gel electrophoresis (PAGE) and silver staining were applied to detect the genetic polymorphisms of LMP2 gene+3152C/T and LMP7gene rs2071543.3.The allelic and genotype frenquencies were calculated by the direct count method,Hardy-Weinberg equilibrium tested whether the study groups were representative.The heterozygosis (H), discrimination power (DP), probability of exclusion(PE)and polymorphic information content (PIC);It analyzed the genetic distrubitions differences in different populations,control and case group using SPSS 16.0 software.Results1. In this study, using PCR-RFLP method with 400 cases in northern Han Chinese individuals,160 cases in Guangxi Zhuang individuals,126 cases of colorectal cancer in individuals of three groups,we analyzed and decided LMP2 gene+3152 C/T and LMP7 gene rs2071543 loci genotypes. In the three groups,LMP2 gene+3152 C/T locus detected CC, CT, TT genotypes, LMP7 gene rs2071543 site detected CC, CA, AA genotypes.Two SNPs sites of the Three groups, genotypes were consistent with the law of Hardy-weinberg equilibrium.2. In the northern Han population,the frequency of allele C in LMP2 gene+3152 C /T locus is 0.7885,allele T is 0.2115, The genotype frequencies of CC,CT and TT were 0.6300,0.3171 and 0.0529; the frequency of allele C in LMP7 gene rs2071543 locus is 0.7977,allele A is 0.2023, The genotype frequencies of CCCA and AA were 0.6300, 0.3353 and 0.0347.3.In guangxi Zhuang population, the frequency of allele C in LMP2 gene+3152 C /T locus is 0.6906,allele T is 0.3094, The genotype frequencies of CC,CT and TT were 0.4937,0.3938 and 0.1125; the frequency of allele C in LMP7 gene rs2071543 locus is 0.8719,allele A is 0.1281, The genotype frequencies of CC,CA and AA were 0.7550,0.1937 and 0.0313.4.In colorectal cancer cases, the frequency of allele C in LMP2 gene+3152 C/T locus is 0.8056,allele T is 0.1944, The genotype frequencies of CC,CT and TT were 0.6587,0.2937 and 0.0476; the frequency of allele C in LMP7 gene rs2071543 locus is 0.8175,allele A is 0.1825, The genotype frequencies of CC,CA and AA were 0.6667, 0.3016 and 0.0317.DiscussionThe northern Han,guangxi Zhuang and colorectal patients were detected by Hardy-Weinberg test,and we found that in the LMP2 gene+3152C/T and LMP7 gene rs2071543,these three populations were consistent with Hardy-Weinberg equilibrium(p>0.05),so,it indicated that these three groups were representive.LMP plays an important role in endogenous antigen processing and presenting,and it was absent or down-regulated causing the occurrence of many tumors,such as small cell lung cancer,malignant melanoma,ovarian carcinoma.cao etc found that LMP7 gene codon 145 polymorphism and esophageal cancer is reletant.Mehta etc found that LMP7 gene codon 145 polymorphism and cervical cancer is reletant. In this study,we researched the relationship of LMP gene+3152 C/T and rs2071543 loci with colorectal cancer study,the results show that there was no genetic relationship beween LMP gene+3152 C/T and rs2071543 loci and colorectal cancerThere are significant differences for Allele frenquencies of LMP2 gene+3152C/T and LMP7 gene rs2071543 in the northern Han population and guang xi Zhuang population; Gene frenquencies of LMP2 gene+3152C/T is not different between the northern Han and Han in henan, Kazak in china,Han in china,Li in hainan, in guangxi Zhuang population,there is significant difference with these populations;For gene frenquencies of LMP7 gene rs2071543, there is significant difference between the northern Han population and Han population in china, the Li Population form hainan,Spain,Germany and There is no difference with Han in henan and Mexican population, in guangxi Zhuang population,the frequency is significantly different from Han population in henan Han population in china,the Li population,Spain,but is not different from Germany and Mexican population. And this distribution differences of LMP7 gene rs2071543 beween different races and populations.This study also assessed the forensic value of LMP gene+3152 C/T and rs2071543 loci in the northern Han and guangxi Zhuang.In the northern Han population, the H,DP,PE and PIC of LMP2 gene+3152 C/T site were 0.3172,0.4997,0.1390 and 0.2779,respectively, the H,DP,PE and PIC of LMP7 gene rs2071543 site were 0.3353,0.4893,0.1353 and 0.2707;In guangxi Zhuang population, the H,DP,PE and PIC of LMP2 gene+3152 C/T site were 0.3938,0.5884,0.1680 and 0.3365,respectively, the H,DP,PE and PIC of LMP7 gene rs2071543 site were 0.1938,0.3608,0.0992 and 0.1984.Conclusion1.Alleles distribution of LMP2 gene+3152C/T and LMP7 gene rs2071543 are consistent with the law of Hardy-weinberg equilibrium in the northern Han,guangxi Zhuang and colorectal patients.2.There is no associations between LMP2 gene+3152C/T and LMP7 gene rs2071543 polymorphisms with sporadic colorectal cancer.3. There are significant differences for Allele frenquencies of LMP2 gene +3152C/T and LMP7 gene rs2071543 in the northern Han population and guang xi Zhuang population; this distribution differences beween different races and populations.4. In guangxi Zhuang populations,LMP2 gene+3152 C/T has a high discriminating ability and in the nortnern Han population, LMP2 gene+3152 C/T has a middle-discriminating ability;LMP7gene rs2071543 loci has a middle-discriminating ability in two populations, the two SNPs loci in the forensic identification and paternity testing have values.