A meta-analysis and experimental data for multidrug resistance genes in breast cancer

BACKGROUND: Increasing trend of breast cancer incidence worldwide is a known fact. This curable disease may become fatal if drug resistance is developed leading to metastatic cancerous tissue. OBJECTIVE: This is a two parts study; a meta-analysis exploring association of drug resistance (mdr1 and ABCG2) genes with breast cancer and mutational association with molecular subtypes of cancer. Methods: PCR-SSCP for genomic polymorphisms and RT-PCR for expression analysis were performed. RESULTS: C3435T polymorphism of mdr1 gene was most commonly studied mutation with contradictory results. Association of ABCG2 gene mutations with untreated breast cancer was reported only by one study so far. Regarding current genomic analysis of mdr1 gene, three novel mutations were found in exon 12 and 2 mutations were found in exon 26. In ABCG2 gene, addition of C and T were found in intron 8 at the intron-exon junction. A positive correlation was observed between these mutations and tumor grade. Levels of mRNA expression revealed that they were over expressed in cancerous tissues compared with controls. CONCLUSION: These findings suggest that these genes are associated with breast cancer.