Genetic association of MMP14 promoter variants and their functional significance in gallbladder cancer pathogenesis.

Gallbladder cancer (GBC) is relatively rare but shows high frequency in certain geographical regions and ethnic groups, which include Northern and Eastern states of India. Previous studies in India have indicated the possible role of genetic predisposition in GBC pathogenesis. Although matrix metalloproteinase-14 (MMP14) is known modulator of tumour microenvironment and tumorigenesis and TCGA data also suggests its upregulation yet, its role in genetic predisposition for GBC is completely unknown. We explored MMP14 promoter genetic variants as risk factors and their implication in expression modulation and the pathogenesis of GBC. We genotyped all single nucleotide polymorphisms of MMP14 promoter by Sanger's sequencing in approximately 300 GBC and 300 control study subjects of Indian ethnicity and, in 26 GBC tissue samples. Protein expression of MMP14 in GBC tissue samples was checked by immunohistochemistry. In vitro luciferase reporter assay was carried out to elucidate role of promoter genetic variants on expression levels in two different cell lines. MMP14 promoter variants, rs1003349 (p value = 0.0008) and rs1004030 (p value = 0.0001) were significantly associated with GBC. Luciferase reporter assay showed high expression for risk alleles of both the SNPs. Genotype-phenotype correlation for rs1003349 and rs1004030, in patient sample, confirmed that risk allele carriers had higher expression levels of MMP14; moreover, the correlation pattern matched with genetic association models. Overall, this study unravels the association of MMP14 promoter SNPs with GBC which contribute to pathogenesis by increasing its expression.