Identification of HNRNPA2B1-regulated miRNA targets in breast cancer cells

Higher N(6)-methyladenosine (m6A) was identified in selected primary microRNAs (pri-miRNAs) as associated with increased levels of the corresponding mature miRNA in MDA-MB-231 triple negative breast cancer (TNBC) cells (PMID: 25799998). HNRNPA2B1 is a reader of the m6A mark in pri-miRNAs and interacts directly with DGCR8 (a component of the nuclear DROSHA complex) to promote processing of pri-miRNAs to precursor-miRNAs (pre-miRNAs) (PMID: 26321680). We have preliminary data showing that HNRNPA2B1 is increased in TAM-resistant, ERα+ LCC9 cells derived from TAM-sensitive, ERα+ MCF-7 breast cancer cells. We found that high HNRNPA2B1 transcript levels in primary breast tumors are associated with reduced overall survival. We postulate that an increase in HNRNPA2B1 targets its binding to additional pri-miRNAs (not normally bound under wild type conditions), resulting in an increase in miRNAs, including those that promote TAM-resistance. The experimental design includes three treatment groups: MCF-7 control transfected with pcDNA 3.1 for 48 h, MCF-7 transfected with pcDNA3.1-HNRNPA2B1 for 48h, and MCF-7 stably transfected with pcDNA3.1-HNRNPA2B1 for 72h.