HNRNPA2/B1 is upregulated in endocrine-resistant LCC9 breast cancer cells and alters the miRNA transcriptome when overexpressed in MCF-7 cells

Abstract

MicroRNAs are dysregulated in breast cancer. Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2/B1) is a reader of the N(6)-methyladenosine (m6A) mark in primary-miRNAs (pri-miRNAs) and promotes DROSHA processing to precursor-miRNAs (pre-miRNAs). We examined the expression of writers, readers, and erasers of m6A and report that HNRNPA2/B1 expression is higher in tamoxifen-resistant LCC9 breast cancer cells as compared to parental, tamoxifen-sensitive MCF-7 cells. To examine how increased expression of HNRNPA2/B1 affects miRNA expression, HNRNPA2/B1 was transiently overexpressed (~5.4-fold) in MCF-7 cells for whole genome miRNA profiling (miRNA-seq). 148 and 88 miRNAs were up- and down-regulated, respectively, 48 h after transfection and 177 and 172 up- and down-regulated, respectively, 72 h after transfection. MetaCore Enrichment analysis identified progesterone receptor action and transforming growth factor β (TGFβ) signaling via miRNA in breast cancer as pathways downstream of the upregulated miRNAs and TGFβ signaling via SMADs and Notch signaling as pathways of the downregulated miRNAs. GO biological processes for mRNA targets of HNRNPA2/B1-regulated miRNAs included response to estradiol and cell-substrate adhesion. qPCR confirmed HNRNPA2B1 downregulation of miR-29a-3p, miR-29b-3p, and miR-222 and upregulation of miR-1266-5p, miR-1268a, miR-671-3p. Transient overexpression of HNRNPA2/B1 reduced MCF-7 sensitivity to 4-hydroxytamoxifen and fulvestrant, suggesting a role for HNRNPA2/B1 in endocrine-resistance.

Interaction between N6-methyladenosine (m6A) modification and noncoding RNAs in cancer

“…In LCC9 breast cancer cells resistant to endocrine, the upregulated HNRNPA2B1 seems to play a more complex role in miRNA transcriptome regulation. In detail, HNRNPA2B1 overexpressed in endocrine-resistant breast cancer cells reduces the sensitivity to 4-hydroxytamoxifen and fulvestrant by upregulating miR-1266-5p, miR-1268a, and miR-671-3p and downregulating miR-29a-3p, miR-29b-3p, and miR-222 [45]. Although previous studies have shown that HNRNPA2B1 can bind to pri-miRNAs and interact with DGCR8 for miRNA processing [39], the mechanism by which HNRNPA2B1 downregulates miRNA remains unclear.…”

The interplay between m6A RNA methylation and noncoding RNA in cancer

“…HNRNPA2/B1 overexpression promotes increases in m6A-modified miRNA levels by enhancing the process by which pri-miRNAs develop into pre-miRNAs and mature miRNAs. Moreover, pre-miRNAs and mature miRNAs can contribute to endocrine resistance by acting on targets or pathways [78]. Knocking down HNRNPA2/B1 can inhibit breast cancer cell proliferation and promote tumor cell apoptosis.…”

Novel insights into the interplay between m6A modification and noncoding RNAs in cancer

“…METTL3 stabilizes YAP and Rho GTPase activating protein 5 (ARHGAP5) to induce cisplatin resistance in NSCLC and in GC [ 69 , 111 ]. HNRNPA2B1 is overexpressed in tamoxifen-resistant breast cancer and reduces 4-hydroxytamoxifen sensitivity [ 112 ]. In addition to METTL3 and METTL14, FTO and YTHDF2 are overexpressed in AML [ 26 , 27 , 113 , 114 ].…”