Abstract 4114: Evaluation of ERCC1 expression and in vitro drug response to cisplatin based on human NSCLC cell lines and primary cultures of human lung cancers

Abstract

Abstract Introduction: In vitro experimentation has been suggested as a rapid tool for identifying and evaluating biomarkers associated with drug response. Excision repair cross-complementation 1 (ERCC1) enzyme plays a rate-limiting role in the nucleotide excision repair pathway and its up regulation has been associated with resistance to platinum agents. Recent studies have suggested that low expression levels of ERCC1 are related to a better survival benefit from cisplatin-based chemotherapy among patients with advanced non-small cell lung carcinoma (NSCLC). This study evaluates the relationship between ERCC1 expression and in vitro drug response to cisplatin using an in vitro chemoresponse assay, ChemoFx® Drug Response Marker (DRM), in human NSCLC cell lines and primary cultures of human lung cancers. Methods: The ChemoFx® DRM was performed on 13 immortalized human NSCLC cell lines (NCI-H520, HOP_92, HOP-62, A549, Calu-3, HCC827, OK, NCI-H460, NCI-H596, NCI-H1666, EKVX, NCI-H358, and NCI-H1975) and 30 primary cultures established from de-identified lung cancer surgical specimens. Cells were treated with a 10-dose range of cisplatin for 72 hours before DAPI-nuclear staining and counting. Response Index scores (RI scores), which are derived from an area under the dose-response curve (AUC), were calculated on the resulting dose-response curves. Protein expression of ERCC1 was evaluated with In-Cell Western analysis. Pearson correlation coefficient was used to show the association between ERCC1 expression and in vitro drug response. Result: Increased ERCC1 expression was significantly associated with cisplatin resistance in the 13 immortalized NSCLC cell lines (r=−0.72, p=0.004). A similar trend was observed across 30 primary cultures of human lung cancers, but the association did not reach the level of significance (r=−0.22, p=0.24). Conclusion: Clinical observation of a negative correlation between ERCC1 expression level and improved survival benefit from cisplatin-based chemotherapy was mirrored by in vitro ChemoFx® DRM analysis with strong correlation in immortalized human NSCLC cell lines and in primary cultures from human lung cancers with a correlation trend. This result suggests the value of in vitro chemoresponse assay in identification and evaluation of biomarkers and their association with chemotherapeutic response. The less significant correlation in human lung cancer primary cultures indicated that ERCC1 alone may not be sufficient for clinical prediction of response in human lung cancers across different pathological subtypes and stages, and additional biomarkers may be involved. These results suggest the value of in vitro chemo response assay, in helping to determine cisplatin response in human lung cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4114. doi:10.1158/1538-7445.AM2011-4114