Therapeutic destruction of insulin receptor substrates for cancer treatment.

Abstract

Insulin receptor substrates 1 and 2 (IRS1/2) mediate mitogenic and antiapoptotic signaling from insulin-like growth factor 1 receptor (IGF-IR), insulin receptor (IR), and other oncoproteins. IRS1 plays a central role in cancer cell proliferation, its expression is increased in many human malignancies, and its upregulation mediates resistance to anticancer drugs. IRS2 is associated with cancer cell motility and metastasis. Currently, there are no anticancer agents that target IRS1/2. We present new IGF-IR/IRS-targeted agents (NT compounds) that promote inhibitory Ser-phosphorylation and degradation of IRS1 and IRS2. Elimination of IRS1/2 results in long-term inhibition of IRS1/2-mediated signaling. The therapeutic significance of this inhibition in cancer cells was shown while unraveling a novel mechanism of resistance to B-RAF(V600E/K) inhibitors. We found that IRS1 is upregulated in PLX4032-resistant melanoma cells and in cell lines derived from patients whose tumors developed PLX4032 resistance. In both settings, NT compounds led to the elimination of IRS proteins and evoked cell death. Treatment with NT compounds in vivo significantly inhibited the growth of PLX4032-resistant tumors and displayed potent antitumor effects in ovarian and prostate cancers. Our findings offer preclinical proof-of-concept for IRS1/2 inhibitors as cancer therapeutics including PLX4032-resistant melanoma. By the elimination of IRS proteins, such agents should prevent acquisition of resistance to mutated-B-RAF inhibitors and possibly restore drug sensitivity in resistant tumors.

• Authors: Hadas Reuveni, Efrat Flashner-Abramson, Lilach Steiner, Kirill Makedonski, Renduo Song, Alexei Shir, Meenhard Herlyn, Menashe Bar-Eli, Alexander Levitzki
• Journal: Cancer research (Cancer Res) Vol. 73 Issue 14 Pg. 4383-94 (Jul 15 2013) ISSN: 1538-7445 [Electronic] United States
• PMID: 23651636 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: ©2013 AACR.

Chemical References

• Antineoplastic Agents
• IRS1 protein, human
• IRS2 protein, human
• Insulin Receptor Substrate Proteins
• Receptor, IGF Type 1
• BRAF protein, human
• Proto-Oncogene Proteins B-raf

Topics

• Animals
• Antineoplastic Agents (pharmacology)
• Cell Line, Tumor
• Down-Regulation (drug effects)
• Female
• HCT116 Cells
• Hep G2 Cells
• Humans
• Insulin Receptor Substrate Proteins (antagonists & inhibitors, genetics, metabolism)
• MAP Kinase Signaling System (drug effects, genetics)
• Melanoma (drug therapy, genetics, metabolism)
• Mice
• Mice, Inbred BALB C
• Mice, Nude
• Neoplasms (drug therapy, metabolism)
• Phosphorylation
• Proto-Oncogene Proteins B-raf (genetics, metabolism)
• Receptor, IGF Type 1 (genetics, metabolism)
• Up-Regulation (drug effects)
• Xenograft Model Antitumor Assays