IRS1 is highly expressed in localized breast tumors and regulates the sensitivity of breast cancer cells to chemotherapy, while IRS2 is highly expressed in invasive breast tumors

Cancer Lett. 2013 Sep 28;338(2):239-48. doi: 10.1016/j.canlet.2013.03.030. Epub 2013 Apr 2.


Insulin receptor substrate (IRS) proteins have been shown to play an important role in breast cancer by differentially regulating cancer cell survival, proliferation, and motility. Furthermore, the IL-4-induced tyrosine phosphorylation of the transcription factor STAT6 was shown to protect breast cancer cells from apoptosis. Here, we analyzed human breast cancer tissues for the expression of IRS1, IRS2, STAT6, and tyrosine phosphorylated STAT6 (pSTAT6). We found that IRS1 and pSTAT6 were both highly expressed in ductal carcinoma in situ (DCIS). On the other hand, IRS2 expression was low in DCIS, but increased significantly in relation to tumor invasiveness. We utilized cell lines with disparate IRS1 expression, MDA-MB-231, MCF7, and MCF7 cells with depleted IRS1 due to shRNA lentiviral infection, to examine the role of IRS1 and IRS2 in the responsiveness of breast cancer cells to chemotherapy. We report that high IRS1 sensitized MCF7 cells to specific chemotherapeutic agents. These results suggest that high IRS1 with low IRS2 expression may predict the effectiveness of specific types of chemotherapy in breast cancer.

Keywords: Breast cancer; Cell death; Chemotherapy; Insulin receptor substrate; STAT6.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Carcinoma in Situ / drug therapy
  • Carcinoma in Situ / genetics
  • Carcinoma in Situ / metabolism
  • Carcinoma in Situ / pathology
  • Carcinoma, Ductal, Breast / drug therapy
  • Carcinoma, Ductal, Breast / genetics
  • Carcinoma, Ductal, Breast / metabolism
  • Carcinoma, Ductal, Breast / pathology
  • Female
  • Humans
  • Insulin Receptor Substrate Proteins / biosynthesis*
  • Insulin Receptor Substrate Proteins / genetics
  • MCF-7 Cells
  • Neoplasm Grading
  • Neoplasm Invasiveness
  • Paclitaxel / pharmacology
  • Phosphorylation
  • STAT6 Transcription Factor / genetics
  • STAT6 Transcription Factor / metabolism
  • Signal Transduction
  • Transfection


  • Antineoplastic Agents
  • IRS1 protein, human
  • IRS2 protein, human
  • Insulin Receptor Substrate Proteins
  • STAT6 Transcription Factor
  • STAT6 protein, human
  • Paclitaxel