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Y. Liu
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P3.02b - Poster Session with Presenters Present (ID 494)
- Event: WCLC 2016
- Type: Poster Presenters Present
- Track: Advanced NSCLC
- Presentations: 1
- Moderators:
- Coordinates: 12/07/2016, 14:30 - 15:45, Hall B (Poster Area)
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P3.02b-041 - Genome-Wide Screen of DNA Methylation Changes Reveals GABBR2 as a Novel Potential Target for EGFR 19 Deletion Adenocarcinoma with Erlotinib (ID 6219)
14:30 - 14:30 | Author(s): Y. Liu
- Abstract
Background:
Lung cancer is the leading cause of cancer related death around the world. The last decade has witnessed the rapid development of epidermal growth factor receptor (EGFR) directly targeted therapies that have significantly changed the treatment of non-small-cell lung cancer (NSCLC). However, the challenge of acquired resistance to EGFR tyrosine kinase inhibitors (TKIs) has been an issue when talking with activating EGFR mutations, which makes it crucial to elucidate the mechanism of EGFR-TKI targeted drug resistance.
Methods:
Methyl-sensitive cut counting sequencing (MSCC), one of the most commonly used whole-genome DNA methylation sequencing technology, was applied to investigate the changes of paired tissue DNA methylation before and after TKI (erlotinib) treatment lasting two cycles with partial response (PR) for stage IIIa (N2) lung adenocarcinoma patients (N=2) with activating EGFR 19 deletion. Sequenom EpiTYPER assay method was further analyzed to double confirm the changed methylated candidate genes in these two patients, through comparing the methylated changes in paired tissues before and after TKI treatment. Western blotting, cell cycle and apoptosis analysis by the up/down regulation of a candidate gene (GABBR2) were performed in three lung adenocarcinoma cell lines, A549 (EGFR wild type), HCC4006 (EGFR 19 deletion, DelL747-E749) and HCC827 (EGFR 19 deletion, DelE746-A750), to elucidate the mechanism of GABBR2 gene in the regulation of EGFR-TKI treatment.
Results:
Sixty aberrant methylated genes were firstly discovered using MSCC method in these two patients harboring EGFR 19 del mutation treated with erlotinib. Two aberrant methylated genes, CBFA2T3 and GABBR2, were clearly validated by the Sequenom EpiTYPER assay subsequently. GABBR2 was significantly down regulated in HCC4006 and HCC827 cells harboring EGFR 19 mutations but remained conservative in A549 cells with EGFR wild-type after erlotinib treatment by Western blotting. The phenomenon was in line with the obvious apoptosis of HCC4006 and HCC827 cell lines after erlotinib treatment, but not in A549 cells. GABBR2 was further induced down regulation after erlotinib exposure through apoptosis method silenced by siRNA using RNAi technology. Meanwhile, GABBR2 gene was demonstrated up regulation rescued the apoptosis significantly, when overexpressing GABBR2 in HCC827 cell lines along with erlotinib treatment.
Conclusion:
Genome-wide screen of DNA methylation changes demonstrated that GABBR2 gene might be as a novel potential treatment target for stage IIIa (N2) EGFR 19 deletion adenocarcinoma with erlotinib treatment. Our research provides a new theoretical basis for the epigenetic study of EGFR mutated lung adenocarcinoma treatment.
