Dissertation
Dissertation > Medicine, health > Oncology > Respiratory system tumors > Lung tumors

The Genetic Variant in the Seed Region of Hsa-mir-499-3p (rs3746444 A>g) Is Associated with the Risk of Human Lung Cancers:a Case-control Study

Author LingXiaoZuo
Tutor LvJiaChun
School Guangzhou Medical College
Course Epidemiology and Biostatistics,
Keywords Lung cancer microRNA Single nucleotide polymorphism
CLC R734.2
Type Master's thesis
Year 2010
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Background Lung cancer is a serious threat to human health, disease, reportedly, lung cancer is highest in the 2009 American Cancer coroner's top, in recent years, the incidence of lung cancer, the mortality rate in China and other developing countries continue to soar, the lung cancer mortality in China's Guangzhou view 1970-1972 11.61/105 32.67/105 from 1990 to 1992 in 1980-1982, of 41.54/105 2000-2002 2002 and then rise to 48.79/105, these shocking figures forced researchers to actively explore The etiology of lung cancer. The study found the population suffering from lung cancer, 80% attributed to tobacco exposure; but only 10% of smokers eventually develop lung cancer, suggesting the formation of lung cancer related to environmental factors, but also depends on the individual's genetic and easy sensibility. In order to analyze the genetic susceptibility of lung cancer, many scholars dedicated to the experimental study of the molecular level, but there are still many issues to be further clarified. miRNA is experienced in vivo of a class of non-coding small RNA, cells from the initial shear miRNA (pri-miRNA) to precursor miRNA (pre-miRNA), pre-miRNA reprocessing for a length of approximately 22 alkali group miRNA mature process. miRNA mature body primarily through complementary to the target gene 3'UTR and 5'UTR combined to regulate expression of target genes, and found that miRNA involved in carcinogenesis process, for example, reported that human lung cancer cell lines hsa-mir-182 combined with RGS17 gene 3'UTR two conserved sites the RGS17 gene regulation. Another example, hsa-mir-21 regulation function abnormalities are known factors associated with many kinds of cancer, recent studies suggest that in non-small cell lung cancer cell lines of hsa-mir-21 through a combination of the tumor suppressor gene PTEN 's the 3'UTR to cut PTEN protein expression. Again, the research of non-small cell lung cancer, come to the K-ras gene 3'UTR to 6 of let-7 binding domain (let-7 complementary sites 6, LCS6) 4 bases on the presence of mutations (followed by 46 individual group experiments prove that the mutation frequency of 5.8%, is the single nucleotide polymorphism, often abbreviated SNP), the let-7 and target a combination of abnormal, increase individual occurrence of non-small cell lung cancer genetic susceptibility possibility; thus detect the SNP in the two populations of the United States of New Mexico and the Boston area, found the SNP with two moderate smokers, non-small cell lung cancer cases and controls in the frequency distribution related. In addition, there are a lot of experiments that may affect the risk of cancer incidence in the target gene mRNA 3'UTR SNP. miRNA sequences on the presence of SNP, whether it will affect the risk of cancer, as well as how the SNP on miRNA sequence affect the occurrence of cancer, a new topic has become today tumor molecular epidemiology. Some scholars have systematically scanned hundreds of miRNA sequences of human cancer tissues and tumor cell lines derived series of mutation sites; subsequent cell tests confirmed, let-7e precursor G gt; mutation (A note of mature cause its mature body 5 'end of the downstream, upstream compared - the mature miRNA 5' end of the first base for a body; precursor of the mutation point downstream 19 bases, denoted by 91) expression was significantly decreased, and further found that the mutation affects the let-7e miRNA mature body from the pre-miRNA processing associated with the occurrence of cancer. 30 Determination of 80 suffering from hereditary ovarian cancer, U.S. researchers candidate miRNA sequences found including hsa-mir-191 precursor C gt; (position denoted by 24) variability seven mutations sites, software forecast derived hsa-mir-191 mutation will become unstable and its secondary structure, and combined with the target maximum free energy change; confirmed through experiments after hsa-mir-191 mutation, reduce its mature expression; further detect mutant genotype patients carrying the locus genotypes of 12 relatives, four of which carry the CA genotype, named CC genotype 4 CA genotype 2 subsequently diagnosed with ovarian cancer, the other eight family members do not carry the mutant genotype were not detected in ovarian cancer disorders; the last inference hsa-mir-191 precursor C gt; A variation will affect the regulation of the tumor suppressor gene or oncogene function, potential genetic susceptibility associated with ovarian cancer. miRNAs 5 'end of the first 2-8 nucleotides known as the seed sequence, seed sequence of miRNA precursor processing, mature, and plays an important role in identification of the target gene, when combined with the mRNA of the target gene, it requires complete complementary base pairing. Pubmed is currently on the reported the miRNA mature body (including seeds sequence) of less than 20 on the SNP and cancer susceptibility literature, nearly miRNA bioinformatic predictions also found that mutations in the seed sequence even mature, is likely conserved sequence means that the seed is a pivotal role for the organism, therefore, if the seed sequence sequence variation, more serious consequences of sequence variation is likely to be more than the pri-miRNA or pre-miRNA. Foreign experiments confirmed on hsa-of miR-125a seed sequence SNP significantly ground affect the processing of pri-miRNA to pre-of miRNA the process, the reporter gene experiments show the SNP weaken the miRNA-mediated translational repression, the Lin-28 protein in the over- accumulate and lead to the occurrence of breast cancer. Another example of hsa-miR-499-3p seed sequence SNP (A gt; G) sites corresponding to the three genotypes, in Nanjing, China, female breast cancer patients and healthy controls, the frequency distribution of a statistically significant difference, the researchers may affect the function of the small RNA After bioinformatics speculated that hsa-miR-499-3p seed sequence SNP, leading to the occurrence of the disease. Found by the search for biological information database, meet smaller allele frequency (MAF) greater than 0.05 4 SNP in miRNA mature in the Chinese population, are: hsa-miR-499-3p, hsa-miR- 608, hsa-miR-196a2, hsa-miR-146a, hsa-miR-499-3p on SNP located in the seed sequence. The bioinformatic predictions also show that, hsa-miR-499-3p research by the National Natural Science Foundation of DNA damage repair gene NBS1 3'UTR exist complementary pairing relationship bear with us. In summary, the present study was to investigate the hsa-miR-499-3p seed sequence the genetic variant (rs3746444 A gt; G) relationship with China Southern crowd lung cancer incidence. The research proposed study hsa-miR-499-3p seed sequence rs3746444 locus A gt; G of the genetic variation associated with China Southern crowd lung cancer incidence, comprehensive research reported discussion of the locus and the risk of cancer incidence; through biological miRNA seed sequence nucleotide mutation bioinformatics prediction to explain the reasons for increased cancer risk; provide for the relevant population of lung cancer prevention, diagnosis and treatment of biomarkers and provide reference for the study of other cancers. Research methods (1) to take the case - control model, first collected 526 cases of primary lung cancer patients in Guangzhou and neighboring cities and from 10,000 healthy community residents randomly selected 526 cases of lung cancer cases gender, age difference of ± 1 years unrelated control; combined with the existing literature, bioinformatic analysis by the appropriate choice of SNP loci; hsa-miR-499-3p seed sequence using PCR-RFLP to detect lung cancer populations and control populations rs3746444 locus genotype; using SAS 9.13 statistical software to analyze the demographic characteristics of the population, and filter out the risk factors, the single factor and genotype non-conditional logistic regression correction confounding factors, the analysis of genetic variation associated with lung cancer incidence and gene - environment interaction. (2) Consolidated rs3746444 locus genetic variation Cancer Research reported meta-analysis to evaluate the genetic variation associated with cancer through the combined effect of the amount. (3) An attempt by the bioinformatics prediction to explain miRNA seed sequence rs3746444 A gt; G mutation when increased cancer risk. Findings (1) In this study, the pathological type classification, adenocarcinoma in 195 cases (37.1%), 526 cases of lung cancer, squamous cell carcinoma, 180 patients (34.2%), 65 cases of large cell lung cancer in 21 cases (4.0%), small cell lung cancer ( 12.4%), adenosquamous carcinoma, mixed lung count 65 cases (12.4%); pathological stage I 73 cases (13.9%), Phase II, 50 cases (9.5%), Phase III (173 cases 32.9%), IV in 230 cases (43.7%). Comparing the control group and the patient group, age and gender, there was no statistical difference (P = 0.084 and P = 0.322), smoking also differences (P = 0.014), drinker was no significant difference in distribution between normal subjects and patients (P = 0.178), family history of cancer were significantly different between the two groups (P = 0.174). hsa-miR-499-3p seed sequence rs3746444 variation sites (A gt; G) exist three genotypes (AA, AG, GG), the distribution of differences in lung cancer cases and control groups was significant (P lt; 0.0001); carrying the wild-type homozygous AA genotype for carrying the AG genotype of lung cancer risk increases by 32% (adjusted OR = 1.32, 95% CI = 1.01-1.81), carrying the GG genotype individual risk of lung cancer, a more marked increase of 122% (OR = 2.22,95% CI = 1.52-3.23); rs3746444 G variant allele number and the risk of lung cancer exist significant dose-response relationship (P-trend = 3.04 × 10-5); stratified analysis showed that carry gt; rs3746444 G variant genotypes (AG GG) individual risk of lung cancer in the age 60 years of age (OR = 2.36, 95% CI = 1.60-3.49); females (OR = 2.49,95% CI = 1.51-4.12); non-smokers (OR = 2.12,95% CI = 1.43-3.15); nondrinkers (OR = 1.73, 95% CI = 1.28-2.34); within three generations immediate family history of cancer prevalence (OR = 1.57,95% CI = 1.19-2.07) crowd even more significantly, the the rs3746444 G mutation may be a lung cancer-related genetic markers. (2) retrieve collected five reports rs3746444 locus variation associated with cancer research, meta analysis of the effect, the results show that the locus of variation [AG GG vs AA] increase cancer risk ( OR = 1.15,95% CI = 1.05-1.26, P = 0.002). (3) bioinformatic predictions might tumor suppressor gene ADAMTS9 found hsa-miR-499-3p of the target genes of one, hsa-miR-499-3p G allele at rs3746444 locus, combined with ADAMTS9 greatest freedom MFE of -31.1 kcal / mol, the rs3746444 locus A allele when it is combined with ADAMTS9 maximum free energy MFE -26.4 kcal / mol smaller, indicating that the stability of its binding, may to making ADAMTS9 easier degradation. Further information analysis also found that the breast ADAMTS9 protein was significantly lower than the adjacent tissues; lung cell lines after asbestos exposure can lead to a decline in its ADAMTS9 gene expression; these changes whether hsa-miR-499-3p rs3746444 A gt; G, worthy of further exploration. Conclusions hsa-mir-499-3p seed sequence (rs3746444 A gt; G) genetic variation can increase the population risk of lung cancer and for the the crowd prevention and treatment of lung cancer biomarkers.

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