Non-Coding Polymorphisms in Nucleotide Binding Domain 1 in <i>ABCC1</i> Gene Associate with Transcript Level and Survival of Patients with Breast Cancer

<div><p>Objectives</p><p>ATP-Binding Cassette (ABC) transporters may cause treatment failure by transporting of anticancer drugs outside of the tumor cells. Multidrug resistance-associated protein 1 coded by the <i>ABCC1</i> gene has recently been suggested as a potential prognostic marker in breast cancer patients. This study aimed to explore tagged haplotype covering nucleotide binding domain 1 of <i>ABCC1</i> in relation with corresponding transcript levels in tissues and clinical phenotype of breast cancer patients.</p><p>Methods</p><p>The distribution of twelve <i>ABCC1</i> polymorphisms was assessed by direct sequencing in peripheral blood DNA (n = 540).</p><p>Results</p><p>Tumors from carriers of the wild type genotype in rs35623 or rs35628 exhibited significantly lower levels of ABCC1 transcript than those from carriers of the minor allele (p = 0.003 and p = 0.004, respectively). The ABCC1 transcript levels significantly increased in the order CT-GT>CC-GT>CC-GG for the predicted rs35626-rs4148351 diplotype. Chemotherapy-treated patients carrying the T allele in rs4148353 had longer disease-free survival than those with the GG genotype (p = 0.043). On the other hand, hormonal therapy-treated patients with the AA genotype in rs35628 had significantly longer disease-free survival than carriers of the G allele (p = 0.012).</p><p>Conclusions</p><p>Taken together, our study shows that genetic variability in the nucleotide binding domain 1 has a significant impact on the ABCC1 transcript level in the target tissue and may modify survival of breast cancer patients.</p>