Heterogeneous nuclear ribonucleoprotein k is involved in the estrogen-signaling pathway in breast cancer

Erina Iwabuchi, Yasuhiro Miki, Takashi Suzuki, Hisashi Hirakawa, Takanori Ishida, Hironobu Sasano

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


Heterogeneous nuclear ribonucleoprotein K (hnRNPK) transcripts are abundant in estrogen receptor (ER)-or progesterone receptor (PR)-positive breast cancer. However, the biological functions of hnRNPK in the ER-mediated signaling pathway have remained largely unknown. Therefore, this study analyzes the functions of hnRNPK expression in the ER-mediated signaling pathway in breast cancer. We initially evaluated hnRNPK expression upon treatment with estradiol (E2) and ICI 182,780 in the ERα-positive breast carcinoma cell line MCF-7. The results revealed that E2 increased hnRNPK; however, hnRNPK expression was decreased with ICI 182,780 treatment, indicating estrogen dependency. We further evaluated the effects of hnRNPK knockdown in the ER-mediated signaling pathway in MCF-7 cells using small interfering RNAs. The results revealed that hnRNPK knockdown decreased ERα expression and ERα target gene pS2 by E2 treatment. As hnRNPK interacts with several other proteins, we explored the interaction between hnRNPK and ERα, which was demonstrated using immunoprecipitation and proximity ligation assay. Subse-quently, we immunolocalized hnRNPK in patients with breast cancer, which revealed that hnRNPK immunoreactivity was significantly higher in ERα-positive carcinoma cells and significantly lower in Ki67-positive or proliferative carcinoma cells. These results indicated that hnRNPK directly in-teracted with ERα and was involved in the ER-mediated signaling pathway in breast carcinoma. Furthermore, hnRNPK expression could be an additional target of endocrine therapy in patients with ERα-positive breast cancer.

Original languageEnglish
Article number2581
Pages (from-to)1-11
Number of pages11
JournalInternational Journal of Molecular Sciences
Issue number5
Publication statusPublished - 2021 Mar 1


  • Breast cancer
  • Estrogen receptor
  • HnRNPK
  • Protein-protein interaction


Dive into the research topics of 'Heterogeneous nuclear ribonucleoprotein k is involved in the estrogen-signaling pathway in breast cancer'. Together they form a unique fingerprint.

Cite this