DNA Damage Sensitivity Profiling Of EGFR Mutant NSCLC Cell Lines And Tissue Explant And Its Relevant Clinical Significance

BackgroundLung cancer is the most common cause of cancer deaths worldwide. Epidermal Growth Factor Receptor (EGFR) is one of the most important driver mutations for Non-Small Cell Lung Cancer (NSCLC). EGFR is well-known to have a much higher incidence among Asian populations. Recent research has found that EGFR mutations can lead to DNA damage repair defects. In addition, it is also found that EGFR mut NSCLC patients has a better response rate to DNA damaging chemotherapeutic drugs like cisplatin, compared to EGFR wt NSCLC patients. However this better response rate is not universial for all EGFR mutant patients. On top of this point, we employed this research project in seek of finding different DNA damage sensitivity of different EGFR mutant NSCLC cell lines after treatment of different cancer drugs.Objectives1. Establish γ-H2AX foci assay to assess the DNA damage sensitivity of cell lines and tissue explants.2. Determine sensitivity of different EGFR mut NSCLC cell lines and EGFR wt NSCLC cell lines before and after treatment of different cancer drugs. Discuss the finding of different drug sensitivty shown by EGFR mut and wt cell lines. Validate the finding in tissue explants.Methods1. Determine DNA damage sensitivity of different EGFR mut and wt NSCLC cell lines in use of γ-H2AX foci assay before and after treatment of five different chemodrugs. Determine survival fractions of different cell lines after treatment of the drugs and correlate survival fractions with γ-H2AX foci counting. 2. Apply γ-H2AX foci assay to tumor explants. Determine DNA damage sensitivity of EGFR mut and wt NSCLC tumor tissue before and after treatment of etoposide. Discuss EGFR mut and wt NSCLC tumor tissue shows different sensitivities to etoposide.Results1. Established γ-H2AX foci assay to assess the DNA damage sensitivity of cell lines and tissue explants, which could precisely measure the DNA damage sensitivity of tumor cell lines and tissue explants.2. Compared to EGFR wt NSCLC cell lines, EGFR mut cell lines show higher DNA damage levels after treatment of DNA damaging chemodrugs. EGFR mut cell lines are more sensitive to DNA damaging drugs.3. Different EGFR mut cell lines show different sensitivity to a specific chemo drug.4. In tissue explants, compared to EGFR wt tumor tissue, EGFR mut tumor tissue is more sensitive to etoposide.Conclusions1. Established γ-H2AX foci assay to assess drug sensitivities of cell lines and tissue explants.2. Different EGFR mutant NSCLC cell lines show different sensitivities to different DNA damaging chemotherapeutic drugs.3. Compared to EGFR wt cell lines, EGFR mut cell lines are more sensitive to DNA damaging drugs, which is also validated in tissue explants.