DNA Polymerase Alpha Subunit B Is a Binding Protein for Erlotinib Resistance in Non-Small Cell Lung Cancer
Tae Young Kim1, Eun Sun Ji2, Ju Yeon Lee2
1Chemical Genomics Global Research Lab, Department of Biotechnology, College of Life Science & Biotechnology, Yonsei University, Seoul 120-749, Korea.
Abstract:
Erlotinib inhibits epithelial growth factor receptor (EGFR) kinase activity and is used to treat non-small cell lung cancer (NSCLC). Despite its high efficacy, recurrence can occur in patients who become resistant to the drug. To address the underlying mechanism of Erlotinib resistance, we investigated additional mechanisms related to mode-of-drug-action, by multiple protein-binding interactions, besides EGFR by using drug affinity responsive target stability (DARTS) and liquid chromatography-mass spectrometry (LC-MS/MS) methods with non-labeled Erlotinib. DNA polymerase alpha subunit B (POLA2) was identified as a new Erlotinib binding protein that was validated by the DARTS platform, complemented with cellular thermal shift assays. Genetic knock-down of POLA2 promoted the anti-proliferative effect of the drug in the Erlotinib-resistant cell line H1299 with high POLA2 expression, whereas the overexpression of POLA2 restored anti-proliferative effects in the Erlotinib-sensitive cell line HCC827 with low POLA2 expression. Importantly, POLA2 expression levels in four NSCLC cell lines were positively correlated with anti-proliferative Erlotinib efficacy (Pearson correlation coefficient, R = 0.9886). These results suggest that POLA2 is a novel complementary target protein of Erlotinib, and could clinically provide validity as a surrogate marker for drug resistance in patients with NSCLC.
Insights
Erlotinib resistance in non-small cell lung cancer (NSCLC) may involve DNA polymerase alpha subunit B (POLA2). POLA2 acts as a novel complementary target for Erlotinib, potentially serving as a resistance marker.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Erlotinib targets epithelial growth factor receptor (EGFR) kinase activity for non-small cell lung cancer (NSCLC) treatment.
- Drug resistance and recurrence limit Erlotinib's long-term efficacy in NSCLC patients.
Purpose of the Study:
- To investigate novel mechanisms of Erlotinib resistance beyond EGFR inhibition.
- To identify additional protein targets of Erlotinib involved in its mode of action.
Main Methods:
- Drug affinity responsive target stability (DARTS) combined with liquid chromatography-mass spectrometry (LC-MS/MS) identified Erlotinib-binding proteins.
- Validation of identified targets using DARTS and cellular thermal shift assays.
- Genetic manipulation (knock-down and overexpression) of candidate proteins in NSCLC cell lines.
Main Results:
- DNA polymerase alpha subunit B (POLA2) was identified as a novel Erlotinib-binding protein.
- POLA2 expression levels correlated positively with Erlotinib efficacy in NSCLC cell lines (R = 0.9886).
- Modulating POLA2 levels affected Erlotinib's anti-proliferative effects in sensitive and resistant cell lines.
Conclusions:
- POLA2 is a novel complementary target of Erlotinib in NSCLC.
- POLA2 may play a role in Erlotinib resistance mechanisms.
- POLA2 expression could serve as a clinical surrogate marker for Erlotinib resistance in NSCLC.
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