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Insulin receptor substrate 1 expression enhances the sensitivity of 32D cells to chemotherapy-induced cell death
Holly A Porter1, Gregory B Carey, Achsah D Keegan
1Center for Vascular and Inflammatory Diseases, Baltimore, MD 21201, USA. hport001@umaryland.edu
Abstract:
The adapters IRS1 and IRS2 link growth factor receptors to downstream signaling pathways that regulate proliferation and survival. Both suppress factor-withdrawal-induced apoptosis and have been implicated in cancer progression. However, recent studies suggest IRS1 and IRS2 mediate differential functions in cancer pathogenesis. IRS1 promoted breast cancer proliferation, while IRS2 promoted metastasis. The role of IRS1 and IRS2 in controlling cell responses to chemotherapy is unknown. To determine the role of IRS1 and IRS2 in the sensitivity of cells to chemotherapy, we treated 32D cells lacking or expressing IRS proteins with various concentrations of chemotherapeutic agents. We found that expression of IRS1, in contrast to IRS2, enhanced the sensitivity of 32D cells to chemotherapy-induced apoptosis. When IRS2 was expressed with IRS1, the cells no longer showed enhanced sensitivity. Expression of IRS1 did not alter the expression of pro- and anti-apoptotic proteins; however, 32D-IRS1 cells expressed higher levels of Annexin A2. In 32D-IRS1 cells, IRS1 and Annexin A2 were both located in cytoplasmic and membrane fractions. We also found that IRS1 coprecipitated with Annexin A2, while IRS2 did not. Decreasing Annexin A2 levels reduced 32D-IRS1 cell sensitivity to chemotherapy. These results suggest IRS1 enhances sensitivity to chemotherapy in part through Annexin A2.
Insights
Insulin receptor substrate 1 (IRS1) enhances chemotherapy sensitivity by upregulating Annexin A2, unlike IRS2. This finding is crucial for understanding cancer treatment responses and developing targeted therapies.
Area of Science:
- Molecular Biology
- Cancer Research
- Cell Signaling
Background:
- Insulin receptor substrates (IRS1 and IRS2) are key adapters in growth factor signaling, regulating cell proliferation and survival.
- Both IRS1 and IRS2 are implicated in cancer progression, with IRS1 promoting proliferation and IRS2 promoting metastasis.
- The differential roles of IRS1 and IRS2 in chemotherapy sensitivity remain largely unknown.
Purpose of the Study:
- To investigate the distinct roles of IRS1 and IRS2 in modulating cellular responses to chemotherapy.
- To determine whether IRS1 or IRS2 influences sensitivity to chemotherapy-induced apoptosis.
Main Methods:
- 32D cells lacking or expressing IRS1 or IRS2 were treated with various chemotherapeutic agents.
- Analysis of apoptosis, pro- and anti-apoptotic protein expression, and Annexin A2 levels.
- Co-precipitation assays to assess IRS1/IRS2 and Annexin A2 interactions.
- Assessment of chemotherapy sensitivity following Annexin A2 knockdown.
Main Results:
- IRS1 expression, but not IRS2, significantly enhanced sensitivity to chemotherapy-induced apoptosis in 32D cells.
- IRS1 expression led to increased Annexin A2 levels and co-precipitation with Annexin A2, while IRS2 did not.
- Reduced Annexin A2 levels diminished the enhanced chemotherapy sensitivity observed in IRS1-expressing cells.
Conclusions:
- IRS1, unlike IRS2, confers enhanced sensitivity to chemotherapy-induced apoptosis.
- IRS1 enhances chemotherapy sensitivity, at least partly, through its interaction with and upregulation of Annexin A2.
- These findings highlight a novel mechanism by which IRS1 influences cancer cell response to treatment.
