JAK2 Inhibition Augments the Anti-Proliferation Effects by AKT and MEK Inhibition in Triple-Negative Breast Cancer Cells

Int J Mol Sci. 2025 Jun 26;26(13):6139. doi: 10.3390/ijms26136139.

Abstract

Janus kinase 2 (JAK2) inhibitors have gained regulatory approval for treating various human diseases. While the JAK2/signal tranducer and activator of transcription 3 (STAT3) pathway plays a role in tumorigenesis, JAK2/STAT3 inhibitors have shown limited therapeutic efficacy in triple-negative breast cancer (TNBC). In this study, we assessed the antiproliferative effects of clinically approved JAK2 inhibitors in TNBC cell lines (MDA-MB-231 and HS578T) using the MTT assay. Among the four JAK2 inhibitors evaluated (fedratinib, cerdulatinib, peficitinib, and filgotinib), fedratinib significantly inhibited the proliferation of TNBC cells with IC50 values below 2 μM. Fedratinib also demonstrated superior efficacy in inhibiting long-term colony formation compared to other JAK2 inhibitors. Western blot analyses showed that fedratinib uniquely inhibits the phosphoinositide 3-kinase (PI3K)/AKT pathway and moderately affects the MAP kinase/ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway, in addition to targeting JAK2/STAT3 signaling. Moreover, fedratinib distinctly decreased MYC and cyclin D1 protein levels while inducing poly (ADP-ribose) polymerase (PARP) cleavage and apoptotic cell death more effectively than other JAK2 inhibitors. We next investigated the effects of simultaneously inhibiting JAK2/STAT3 together with the MEK/ERK or PI3K/AKT pathways, as well as the impact of triple pathway inhibition. Notably, combining ceduratinib with either cobimetinib (MEK inhibitor) and ipatasertib (AKT inhibitor) or trametinib (MEK inhibitor) and alpelisib (PI3K inhibitor) mimicked the effects of fedratinib on the cell proliferation, MYC and cyclin D1 suppression, and pro-apoptotic protein induction. These finding suggest that JAK2 inhibition enhances the anticancer effects of concurrent MEK/ERK and PI3K/AKT pathway inhibition, while JAK2 inhibition alone shows minimal efficacy in TNBC cells.

Keywords: JAK2/STAT3 pathway; MEK/ERK pathway; PI3K/AKT pathway; anticancer; combination; protein kinase inhibitors; triple-negative breast cancer.

MeSH terms

  • Apoptosis / drug effects
  • Benzenesulfonamides
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Female
  • Humans
  • Janus Kinase 2* / antagonists & inhibitors
  • Janus Kinase 2* / metabolism
  • MAP Kinase Signaling System / drug effects
  • Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Protein Kinase Inhibitors* / pharmacology
  • Proto-Oncogene Proteins c-akt* / antagonists & inhibitors
  • Proto-Oncogene Proteins c-akt* / metabolism
  • Pyrrolidines
  • STAT3 Transcription Factor / metabolism
  • Signal Transduction / drug effects
  • Sulfonamides / pharmacology
  • Triple Negative Breast Neoplasms* / drug therapy
  • Triple Negative Breast Neoplasms* / metabolism
  • Triple Negative Breast Neoplasms* / pathology

Substances

  • Janus Kinase 2
  • Proto-Oncogene Proteins c-akt
  • Protein Kinase Inhibitors
  • JAK2 protein, human
  • fedratinib
  • STAT3 Transcription Factor
  • Mitogen-Activated Protein Kinase Kinases
  • Sulfonamides
  • Phosphatidylinositol 3-Kinases
  • Benzenesulfonamides
  • Pyrrolidines