Association Of The SNP In The MMP-1 And MMP-3 Promoter Modifies Polymorphism With Susceptibility To Endometriosis

Objective: Endometriosis (EMs) is a common gynecologic disease, developing mostly in women of reproductive age. It is one of the most familiar reasons of infertility and chronic pelvic pain. The etiology and pathogenesis of endometriosis are still unclear. There is increasing evidence that endometriosis is inherited as a complex genetic trait and associated with polymorphisms in candidate genes, implying that multiple gene loci interact with each other and with the environment to produce the disease phenotype. Like carcinoma, endometriosis has the unique characteristics of invasion and metastasis, though it is a benign tumor. The degradation of extracellular matrix (ECM) barrier is essential for invasion and metastasis. Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that degrade the extracellular matrix and basement membrane (BM) in a substrate-specific manner and are thought to have important roles in progression of many physiology and pathology, there would be appear to contribute to the development of endometriosis. MMP-1, MMP -2, MMP -3, MMP -9 and MMP -11 have been given considerable attention for their roles in degradation of uterine endometrial cells. The MMP1 and MMP3 genes are neighborly localized on chromosome 11q22. Recent studies have found that there are some single nucleotide polymorphism (SNP) located in MMPs that partially influence structure and function of these genes and relate to occurrence and development of diseases. The MMP-1 promoter contains a single nucleotide polymorphism at -1607 bp, which creates an ETs binding site by the addition of a guanine, and influence the transcriptional level of this gene. Similarly, the insertion/deletion mechanism of an A nucleotide at -1171 bp in the MMP-3 gene promoter sequence results in a polymorphism (5A/6A) in which the transcriptional activity of the 5A homozygous is approximately double that of the 6A homozygous. The MMP-1 and MMP-3 SNP have been described in numerous cancers, including breast cancer, lung cancer, renal cell carcinomas, colorectal cancer, cervical cancer, ovarian cancer and endometrial carcinomas. To the best of our knowledge, the relationship between the MMPs SNP and risk of the development of endometriosis has not been documented. In this study we investigate the MMP-1 and MMP-3 DNA polymorphism in a hospital based case-control study to determine whether the MMP-1 and MMP-3 genepolymorphism play a part in genetic susceptibility to endometriosis. In order to control for potential regional differences in allelotype expression, we have tested our hypothesis on a cohort of endometriosis patients and controls from northern Chinese Han population. Methods: 100 patients with endometriosis were recruited from the gynecology and obstetrics department of the Fourth Affiliated Hospital of Hebei Medical University from December 2002 to December 2004. All the patients were confirmed by clinic and histology. 150 healthy volunteers who had no clinical evidence of endometriosis were randomly selected from Chinese blood donors as control subjects. All cases and controls were from Chinese Han population. Clinically, endometriosis was staged according to the revised American Fertility Society (r-AFS) classification. General information of the patients were recorded in detail in the medical chart. The information of healthy controls were obtained by questionary. Five milliliter of venous blood from each subject was drawn in Vacutainer tubes containing EDTA and stored at 4℃. The genomic DNA was extracted within one week after bleeding by using proteinase K digestion followed by a salting out procedure. We analyzed the allele and genotype frequencies using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genotype frequencies and allelefrequencies were compared in the patients and the controls using Chi-squared (χ~2) analysis and logistic regression. The MMP-1 and MMP-3 haplotype frequencies and linkage disequilibrium coefficient were estimated by using EH and 2ld linkage software. Results: The distribution of the MMP-1 and MMP-3 genotypes in healthy controls and endometriosis patients did not significantly deviate from that expected for Hardy-Weinberg equilibrium. (1). MMP-1 promoter SNP with susceptibility to endometriosis: The frequency of 2G allele among endometriosis patients (79%) was significantly higher than healthy controls (66.9%) (χ~2=8.53, P=0.003). In cases, the frequencies of the 2G/2G, 2G/1G and 1G/1G genotypes were significantly different from that in healthy controls (χ~2=6.99 , P=0.03). The frequency of 2G homozygotes in endometriosis was higher than controls (χ~2=5.26,P=0.02). Compared with the 1G/1G genotype, both the 2G/2G and in combination with the 1G/2G genotype significantly modified the risk of developing endometriosis, the adjusted odds ratio was 3.65 (95%CI=1.41~9.43) and 3.25 (95%CI=1.29~8.23), respectively. (2). MMP-3 promoter SNP with susceptibility to endometriosis: The frequencies of the 5A and 6A allele among endometriosis patients and healthy controls were 14%,86% and 20.3 %,79.7%, respectively. There was no statistical difference inallele distribution between endometriosis patients and controls (χ~2=3.29 , P=0.07). There was no significant difference of genotype distribution in endometriosis patients and healthy women (χ~2=3.58,P=0.167) too. Compared with the 6A/6A genotype, neither the 5A/5A nor in combination with the 5A/6A genotype significantly modified the risk of developing endometriosis, the adjusted odds ratio was 2.51 (95%CI=0.25~25) and 1.63 (95%CI= 0.92~2.98), respectively. (3). The combined effect of the MMP-1 and MMP-3 single nucleotide polymorphism on the risk of endometriosis was analyzed by using the EH program: The overall distribution of the MMP haplotypes in endometriosis patients and healthy controls showed significant difference (P=0.00). Compared with the 1G/6A haplotype, 2G/6A haplotype significantly modified the risk of developing endometriosis, the adjusted odds ratio was 3.12 (95%CI= 1.83~5.33). (4). The analysis of the linkage disequilibrium between MMP-1 and MMP-3: Our study showed there was an significant linkage disequilibrium between the 1G/2G MMP-1 and the 5A/6A MMP-3 polymorphism (D'=0.47, χ~2=61.94,P=0.00). Conclusion: Individuals with the MMP-1 2G allele significantly increased risk of the developing endometriosis; Although MMP-3 promoter SNP could not be used as a separatly alone stratified marker to predict the risk of...