Ribonucleoprotein HNRNPA2B1 interacts with and regulates oncogenic KRAS in pancreatic ductal adenocarcinoma cells

Gastroenterology. 2014 Oct;147(4):882-892.e8. doi: 10.1053/j.gastro.2014.06.041. Epub 2014 Jul 3.

Abstract

Background & aims: Development of pancreatic ductal adenocarcinoma (PDAC) involves activation of c-Ki-ras2 Kirsten rat sarcoma oncogene homolog (KRAS) signaling, but little is known about the roles of proteins that regulate the activity of oncogenic KRAS. We investigated the activities of proteins that interact with KRAS in PDAC cells.

Methods: We used mass spectrometry to demonstrate that heterogeneous nuclear ribonucleoproteins (HNRNP) A2 and B1 (encoded by the gene HNRNPA2B1) interact with KRAS G12V. We used co-immunoprecipitation analyses to study interactions between HNRNPA2B1 and KRAS in KRAS-dependent and KRAS-independent PDAC cell lines. We knocked down HNRNPA2B1 using small hairpin RNAs and measured viability, anchorage-independent proliferation, and growth of xenograft tumors in mice. We studied KRAS phosphorylation using the Phos-tag system.

Results: We found that interactions between HRNPA2B1 and KRAS correlated with KRAS-dependency of some human PDAC cell lines. Knock down of HNRNPA2B1 significantly reduced viability, anchorage-independent proliferation, and formation of xenograft tumors by KRAS-dependent PDAC cells. HNRNPA2B1 knock down also increased apoptosis of KRAS-dependent PDAC cells, inactivated c-akt murine thymoma oncogene homolog 1 signaling via mammalian target of rapamycin, and reduced interaction between KRAS and phosphatidylinositide 3-kinase. Interaction between HNRNPA2B1 and KRAS required KRAS phosphorylation at serine 181.

Conclusions: In KRAS-dependent PDAC cell lines, HNRNPA2B1 interacts with and regulates the activity of KRAS G12V and G12D. HNRNPA2B1 is required for KRAS activation of c-akt murine thymoma oncogene homolog 1-mammalian target of rapamycin signaling, interaction with phosphatidylinositide 3-kinase, and PDAC cell survival and tumor formation in mice. HNRNPA2B1 might be a target for treatment of pancreatic cancer.

Keywords: Carcinogenesis; Mouse Model; Oncogene; Signal Transduction.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis
  • Carcinoma, Pancreatic Ductal / genetics
  • Carcinoma, Pancreatic Ductal / metabolism*
  • Carcinoma, Pancreatic Ductal / pathology
  • Cell Adhesion
  • Cell Proliferation
  • Cell Survival
  • Gene Expression Regulation, Neoplastic
  • Gene Knockdown Techniques
  • HeLa Cells
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / genetics
  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B / metabolism*
  • Humans
  • Mice
  • Pancreatic Neoplasms / genetics
  • Pancreatic Neoplasms / metabolism*
  • Pancreatic Neoplasms / pathology
  • Phosphatidylinositol 3-Kinase / metabolism
  • Phosphorylation
  • Protein Binding
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins p21(ras)
  • RNA Interference
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism
  • Time Factors
  • Transfection
  • Tumor Burden
  • Xenograft Model Antitumor Assays
  • ras Proteins / genetics
  • ras Proteins / metabolism*

Substances

  • Heterogeneous-Nuclear Ribonucleoprotein Group A-B
  • KRAS protein, human
  • Proto-Oncogene Proteins
  • hnRNP A2
  • MTOR protein, human
  • Phosphatidylinositol 3-Kinase
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins