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Characterization of kinase suppressor of Ras-1 expression and anticancer drug sensitivity in human cancer cell lines
Scott M Stoeger1, Kenneth H Cowan
1Eppley Institute for Research in Cancer and Allied Diseases, 986805 Nebraska Medical Center, University of Nebraska Medical Center, Omaha, NE, 68198, USA.
Abstract:
Previous studies have indicated that the ERK1/2 MAP kinase signaling pathway plays an important role not only in cell growth, cell cycle regulation, and differentiation, but also in determining the sensitivity of cells to anticancer agents as well. Furthermore, expression of kinase suppressor of Ras-1 (KSR1), a molecular scaffold that modulates signaling through the ERK1/2 MAP kinase pathway, has been shown to influence the cellular sensitivity to the anticancer agent cisplatin. To further define the role of KSR1 expression on drug sensitivity, the expression of KSR1 was examined in the NCI60 anticancer drug screen, a panel of cancer cell lines representing nine tissue types, established by the Developmental Therapeutics Program (DTP) at the National Cancer Institute (NCI). The expression of thousands of molecular targets has been examined in the NCI60 panel as well as the cellular toxicity for greater than 400,000 compounds. KSR1 expression varied almost 30-fold difference between the highest and lowest expressing cell lines in the NCI60. Using the COMPARE analysis algorithm, KSR1 expression was correlated with sensitivity of the compounds screened by DTP and several novel agents were identified whose sensitivity correlated with KSR1 expression in the NCI60 panel. Cytotoxicity of two agents, cytochalasin H and tunicamycin, identified through the COMPARE analysis of KSR1 expression and drug sensitivity, was also examined in wild type (KSR(+/+)) mouse embryo fibroblasts (MEFs) and MEFs deficient in KSR1 expression (KSR1(-/-)). These studies demonstrated enhanced sensitivity, as well as increased ERK activation, in KSR(-/-) MEFs following exposure to tunicamycin or cytochalasin H compared to KSR(+/+) MEFs. Furthermore, restoration of KSR1 expression in KSR(-/-) MEFs following stable transduction of cells with a KSR1 expression vector, enhanced sensitivity of cells to tunicamycin and cytochalasin H and decreased ERK1/2 activation following exposure to these drugs. In addition, the sensitivity to cytochalasin H and tunicamycin of breast cancer cell lines with low KSR1 expression, (HS578T and MDA-MB-231/ATCC), was increased relative to the sensitivity of breast cancer cells with higher levels of KSR1 (MCF7). These studies indicate that KSR1 may play an important role in the determination of cellular sensitivity to anticancer agents.
Insights
Kinase suppressor of Ras-1 (KSR1) influences cancer drug sensitivity. Lower KSR1 expression correlates with increased sensitivity to certain anticancer agents, suggesting KSR1
Area of Science:
- Molecular Biology
- Cancer Research
- Pharmacology
Background:
- The ERK1/2 MAP kinase pathway is crucial for cell growth, differentiation, and drug sensitivity.
- Kinase suppressor of Ras-1 (KSR1) is a scaffold protein modulating ERK1/2 signaling and impacting cellular response to anticancer drugs like cisplatin.
Purpose of the Study:
- To investigate the role of KSR1 expression in determining cellular sensitivity to various anticancer agents.
- To identify novel anticancer agents whose efficacy correlates with KSR1 expression levels.
Main Methods:
- Examined KSR1 expression across the NCI60 cancer cell line panel.
- Utilized COMPARE analysis to correlate KSR1 expression with drug sensitivity data.
- Assessed the cytotoxicity of cytochalasin H and tunicamycin in KSR1-deficient and wild-type mouse embryo fibroblasts (MEFs).
- Restored KSR1 expression in KSR1-deficient MEFs to evaluate its impact on drug sensitivity and ERK activation.
Main Results:
- KSR1 expression varied significantly across the NCI60 panel.
- Correlations between KSR1 expression and sensitivity to novel agents were identified.
- KSR1-deficient MEFs showed enhanced sensitivity and increased ERK activation upon exposure to cytochalasin H and tunicamycin.
- Restoration of KSR1 expression in deficient MEFs reduced ERK activation and modulated drug sensitivity.
- Breast cancer cell lines with low KSR1 expression exhibited increased sensitivity to cytochalasin H and tunicamycin.
Conclusions:
- KSR1 expression levels play a significant role in modulating cellular sensitivity to specific anticancer agents.
- Targeting KSR1 or understanding its expression may offer new strategies for cancer therapy.
- The findings highlight KSR1 as a potential biomarker for predicting response to certain chemotherapeutics.
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