Abstract 4893: The use of glycyrrhetinic acid derivatives to inhibit blebbishield emergency program pathogenesis overcoming erlotinib resistance in non-small cell lung cancer
Authors: Ebony Nottingham, Elizabeth Mazzio, Arindam Mondal, Mandip Sachdeva
Journal: Cancer Research (2018)

Abstract Background: Bleb transformation is an initial induction of apoptosis leading to cellular compartmentalization into vesicles, increased glycolysis/mitochondrial activity combined with dynamin mediated endocytosis allowing the cell to tether vesicles to form stem like spheroids protecting exposed genetic material. Our laboratory has found that not only do both Erlotinib sensitive and resistant cell lines undergo blebbishield transformation in response to treatment, but the addition of Glycyrrhetinic acid derivative (CDODA-Me) overwhelms this pathway leading to cellular apoptosis. Methods: NSCLC cell lines HCC827 (both erlotinib resistant and sensitive), were treated with CDODA-Me and Erlotinib (combination and single treatment). MicroRNA expression profiling was used to identify and validate reference genes involved with the synergistic effects comparing combination treatment to erlotinib single treatment groups. Spheroids were collected after 24hr treatment using blebbishield extraction media (BEM) consisting of 12µM erlotinib alone and in combination with 2µM CDODA-Me. Western Blot analysis was used to confirm identified pathways as well as to quantify the effects of CDODA-Me on VEGF and TGF-β cellular release levels during treatment as well as MET and EGFR kinase activation. Results: Genomic studies showed an increase in microRNA has-miR-711 (approximately 4-fold) which is responsible for inhibiting dynamin mediated trafficking, various growth factor expression levels (including VEGF and TGF-β), as well as the expression of receptors associated with these growth factors (EGFR, MET, VEGFR). This inhibition was confirmed through western blot analysis showing a decrease in receptor activation but no effects on receptor expression (6 fold and 8 fold decrease when compared to erlotinib single treatment for EGFR and MET respectively). Sphere reattachment was found to be dependent on the presence of growth factors and other unknown cell signaling molecules through the fact that spheres did not attach in fresh media, but attached in as little as 3hrs in media obtained after 24hr incubation in parental cells. Media obtained after incubation in parental cells provided higher levels of VEGF and TGF-β when compared to media obtained after 24hr treatment with (resistant to non-resistant expression ratios of 3.94 and 4.06 for HCC827 (4µM erlotinib resistant) and HCC827 Cl4 respectively). Actin fluorescent staining 48hrs after reseeding spheroids showed that cells grown in untreated parental media regained normal branch like morphology while those grown in CDODA-Me treated parental media remained rounded and died. Conclusions: Based on the results of these studies, CDODA-Me has been shown to inhibit NSCLC cell types from overcoming apoptosis thereby inhibiting increased drug resistance as well as tumorgenicity. Citation Format: Ebony Nottingham, Elizabeth Mazzio, Arindam Mondal, Mandip Sachdeva. The use of glycyrrhetinic acid derivatives to inhibit blebbishield emergency program pathogenesis overcoming erlotinib resistance in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4893.