ABCB1 Amplicon Contains Cyclic AMP Response Element-Driven TRIP6 Gene in Taxane-Resistant MCF-7 Breast Cancer Sublines

A limited number of studies are devoted to regulating expression in cancer. Hence, we aimed to unveil the regulation of expression in MCF-7 breast cancer cells (with high expression) and taxane-resistant MCF-7 sublines (manifesting even higher expression). We found that transcription is regulated primarily by the cyclic AMP response element (CRE) in hypomethylated proximal promoters in both taxane-sensitive and taxane-resistant MCF-7 cells. Furthermore, in taxane-resistant MCF-7 sublines, co-amplification with the neighboring gene, as witnessed by fluorescence in situ hybridization (FISH), led to overexpression. Ultimately, we found high mRNA levels in progesterone receptor-positive breast cancer and samples resected from premenopausal women.