Study On Risk Factors And Susceptibility Genes In Uterine Leiomyoma

Uterine leiomyoma is the most common benign reproductive system tumor in women.Although uterine leiomyoma is benign, its prevalence is high in women of childbearing age.Early studies suggest that uterine leiomyoma is an estrogen-dependent disease, and estrogenand progesterone play an important role in the occurrence and development of fibroma. Recentresearch found that the occurrence of uterine leiomyoma may be related to the imbalancebetween apoptosis and proliferation. So far the pathogenesis of uterine leiomyoma was not clear,and its occurrence and development are related with endocrine, genetic, reproductive and otherinternal factors and environmental harmful exposure, gynecological inflammation, feedingfactors.ObjectiveTo investigate the risk factors of uterine leiomyoma, cases of uterine leiomyoma andcontrols in Northern Han Chinese were investigated about epidemiological data, includingmenstrual history, fertility and birth control history, disease history and current condition. Forthe purpose of finding uterine leiomyoma susceptibility gene, single nucleotide polymorphismsof AhR gene and AhR protein expression in uterine leiomyoma and the surrounding normalmyometrium tissues was detected.Methods:Patients of uterine leiomyoma and non-hysteromyoma female controls aged of 20-60, notaking estrogen drugs in three months in the same period were from a 3A hospital-top level inChangchun City, from2005.9 to 2008.9. Patients with other gynecologic tumors andhormone-related diseases were excluded. Epidemiological investigation were imposed on all ofobjects according to the questionnaire, and datas of general situation, menstrual history, fertilityand birth control history, disease history and current condition were acquired.In this study, using aryl hydrocarbon receptor as a candidate gene and single nucleotide polymorphisms as genetic marker, polymerase chain reaction - restriction fragment lengthpolymorphism (PCR-RFLP) technique was applied to detect SNPs of AhR gene, andimmunohistochemistry (SP) staining method was taken to detect the aryl hydrocarbon receptorprotein expression in uterine leiomyoma and surrounding normal myometrial tissue.In the statistical analysis of epidemiological data, Chi-square test was used for qualitativedata, and t test was for quantitative data. Test of goodness of fit was applied to calculate for thegenotype frequency distribution in each SNP locus according to Hardy-Weinberg law.UNPHASED2.404 software was used to analyze single locus allele and genotype distributionand the association with the occurrence of uterine leiomyoma. The relationship between locusinteraction and uterine leiomyoma was analyzed by haplotype. Through Image-Pro Plus 6.0(IPP 6.0) software analysis, immunohistochemical staining optical density and average integraloptical density was measured, and the difference of aryl hydrocarbon receptor between inuterine leiomyoma and normal myometrial tissues was analyzed by t test.Results:(1)Age of uterine leiomyoma patients concentrated in the range of 31 ~ 50 years old,accounting for 79.4 percent of the total number of samples, especially of 41~50-year-old. whenthe pregnancy times≥3 , the risk of uterine leiomyoma reduced, and the incidence of uterineleiomyoma was increased with abortion times. The sizes of fibroids in the patients was morethan 1.0cm mostly, accounting for 95.9%, and 64.7% of which were more than 5.0cm. Multiplefibroids were most common, accounting for 70.0%. Fibroids found in uterine body accountedfor 92.4%, and the ones in muscle intramural were most common, accounting for 56.47%.(2)The differences of genotype and allele distribution in rs3802083 locus weresignificant between cases and controls. Compared to controls, genotype distribution inrs713150 locus was significant, but allele distribution was not.Association between Haplotype rs3802083-rs713150 and uterine leiomyoma was found (P<0.05). In rs3802083-rs713150 haplotype system, rs3802083 (G)-rs713150 (C) was more andrs3802083 (A) - rs713150 haplotype was less in case group (P < 0.05).(3)GenerallyAhR protein of staining was distributed in the cytoplasm of uterine smoothmuscle cells, with strong positive staining gathered into large pieces. AhR-positive stainingintensity of uterine leiomyoma was low, evenly distributed in the cytoplasm of uterineleiomyoma smooth muscle cells. Less strong staining were found which aggregated into small pieces.Between normal myometrium and leiomyoma, the difference of average optical densitywas not significant, and so was integral optical density.Conclusions:(1)Age of uterine leiomyoma patients concentrates in the range of 31~50 years old,especially of 41~50-year-old. Multiple fibroids are common, and often occurred in uterine body.The risk of uterine leiomyoma reduced with the rise of pregnancy times, and increased withabortion times.(2)AhR gene rs3802083 may be susceptibility loci of uterus hysteromyoma in ChineseHan population. Females carrying rs3802083 G/G genotype are probably susceptible tohysteromyoma. Rs3802083-rs713150 haplotype system is related with uterine fibroids, and, asusceptibility locus of uterine leiomyoma possibly exists in haplotype including rs3802083 (G)allele. Maybe there is a resistance site in the haplotype containing rs3802083 (A) allele. Theresults suggest that AhR gene may be a susceptibility gene of uterine leiomyoma.(3)Between in normal myometrium and in leiomyoma, no difference in the extent ofAhR-positive staining, the number of positive cells and the overall staining degree the wasfound. There was no difference in AhR protein expression found between normal myometriumand leiomyoma tissue.