Breast cancer remains a leading threat to women’s health. This study reports that the m6A reader HNRNPC is aberrantly upregulated in breast cancer and that its knockdown inhibits tumor progression. Using RNA immunoprecipitation and related assays, the authors show that HNRNPC recognizes and binds a continuous uridine-rich region in the 3′UTR of m6A-modified DDX6 mRNA in the nucleus, maintaining DDX6 mRNA stability. Additionally, estrogen receptor alpha (ERα) is identified as a transcription factor that binds the HNRNPC promoter and increases HNRNPC expression. The authors propose an ERα/HNRNPC/DDX6 axis that promotes proliferation and metastasis in ER+ breast cancer and suggest HNRNPC as a potential therapeutic target.
Breast cancer (BC) is increasingly prevalent worldwide and, despite improvements in localized disease outcomes, advanced metastatic BC still carries poor survival. Epigenetic mechanisms, including RNA methylation such as N6-methyladenosine (m6A), contribute to the regulation of tumor biology. The m6A system comprises writers (methyltransferases), erasers (demethylases), and readers that recognize m6A-modified RNA and influence RNA fate.
Readers are pivotal because they determine the functional consequences of m6A marks. Examples in BC biology include IGF2BP3-mediated RNA stabilization and YTHDF2-mediated RNA decay, while YTHDF1 has been shown to promote translation. Heterogeneous nuclear ribonucleoprotein C (HNRNPC) is a reader protein reported to be highly expressed in many tumors and to influence RNA metabolism and alternative splicing. Prior work has indicated that m6A-induced changes in RNA structure can alter binding by HNRNPC, suggesting that HNRNPC–RNA interactions may depend on RNA structural switches induced by m6A.
DEAD-box helicase 6 (DDX6) is an RNA helicase primarily located in P-bodies and stress granules and has been reported as oncogenic in other cancers through post-transcriptional regulation of targets such as HER2, FGFR2, and c-Myc. Its role and regulation by m6A in breast cancer were previously unclear.
This study focuses on m6A readers in BC, identifies HNRNPC upregulation, links ERα to HNRNPC transcriptional activation, and demonstrates that HNRNPC binds and stabilizes m6A-modified DDX6 mRNA, forming an ERα/HNRNPC/DDX6 axis that facilitates ER+ BC proliferation and metastasis.
Total RNA was extracted using TRIzol reagent and reverse-transcribed with HiScript II RT SuperMix for qPCR. Quantitative PCR used AceQ qPCR SYBR Green Master Mix on an Applied Biosystems instrument. GAPDH and U6 were used for normalization. Primer sequences are listed in Supplementary Table 1 of the source article.
Proteins were isolated using RIPA lysis buffer with PMSF and protease/phosphatase inhibitors. Samples were separated by SDS-PAGE, transferred to PVDF membranes, blocked in 5% skim milk, incubated with primary antibodies overnight at 4 °C, washed, incubated with secondary antibodies, and visualized with ECL substrate using a ChemiDoc imaging system. Antibody details are provided in Supplementary Table 2 of the source article.
Six paired invasive breast carcinoma (IBC) tissues and adjacent normal breast tissues were collected from patients who underwent surgery at Breast and Thyroid Surgery, Wuhan Union Hospital, Huazhong University of Science and Technology (HUST). All tissues were pathologically confirmed and frozen in liquid nitrogen. Informed consent was obtained, and the study was approved by the HUST Human Research Ethics Committee.
Human IBC cell lines MCF7 and T47D, and the non-tumorigenic breast epithelial cell line MCF-10A were obtained from ATCC. MCF7 cells were cultured in DMEM with 10% fetal bovine serum; T47D cells were cultured in RPMI-1640 with 10% fetal bovine serum. Further culture conditions and experimental manipulations are described in the full article.
The authors report that HNRNPC expression is abnormally high in breast cancer. Knockdown experiments showed that reducing HNRNPC levels inhibited BC progression in vitro, and xenograft models confirmed an oncogenic role for HNRNPC in vivo. RNA immunoprecipitation and RIP-Seq indicated that HNRNPC recognizes and binds to a continuous uridine-rich region in the 3′UTR of m6A-modified DDX6 mRNA within the nucleus. This interaction preserves DDX6 mRNA stability in a manner that depends on m6A modification. Transcriptomic analyses implicated ERα as a positive regulator of HNRNPC expression; chromatin immunoprecipitation (ChIP) assays showed ERα binding to the HNRNPC promoter, supporting transcriptional upregulation by ERα. Together, these observations define an ERα/HNRNPC/DDX6 axis that promotes proliferation and metastatic behaviors in ER+ breast cancer.
Note: The provided source excerpt describes the experimental approaches and key conclusions. Detailed quantitative results, statistical analyses, full datasets, exact binding sites, sequence motifs, and numerical effect sizes were not included in the excerpt and therefore are not reported here.
The study positions HNRNPC as a clinically relevant m6A reader that links estrogen signaling to post-transcriptional control of an oncogenic RNA helicase, DDX6, in ER+ breast cancer. By showing that ERα transcriptionally upregulates HNRNPC and that HNRNPC stabilizes m6A-modified DDX6 mRNA via binding to a uridine-rich 3′UTR region, the authors propose a mechanistic axis driving tumor growth and metastasis. Given prior evidence that readers determine RNA fate and that m6A can modulate RNA structure to influence protein binding, the findings support the model that m6A-dependent structural changes enable HNRNPC to recognize and stabilize specific transcripts.
The authors suggest that targeting HNRNPC could represent a therapeutic strategy for ER+ breast cancer. However, specific therapeutic approaches, efficacy data, and safety profiles were not provided in the available excerpt.
For full experimental details, quantitative results, and supplementary materials including primer and antibody lists, readers should consult the complete article and its supplementary files.