Abstract 1974: Autocrine TIMP-1-mediated chemoresistance via induction of IL-6 in NSCLC

Abstract

Abstract Our previous studies have confirmed the well-defined antiapoptotic functions of TIMP-1. We have shown that overexpressing TIMP-1 in NSCLC cells increases cell survival with activation of the ERK pathway via phosphorylation of BAD at serine 112. Knocking down TIMP-1 in NSCLC cells increased the levels of miR-125a-5p with concomitant upregulation in apoptosis. These studies beg the question- does modulation of TIMP-1 affect chemotherapy in NSCLC? To address this question we examined two cell lines, A549 and H460, and their specific shRNA-mediated TIMP-1 gene knockdown clones. We found that TIMP-1 mediated chemoresistance against two front line chemotherapeutic agents (Gemcitabine and Cisplatin) as determined by increased apoptosis in the KD clones. In order to determine any contribution of cytokine activity towards this antiapoptotic function of TIMP-1, we carried out a cytometric bead array assay. The results of this screening assay which included potential inflammatory cytokines and growth factors, indicated that IL-6 plays a role in mediating the chemoresistance in TIMP-1 expressing NSCLCs. We then determined endogenous IL-6 levels in our array of NSCLC cell lines and found a direct correlation of IL-6 levels with TIMP-1 levels. It is important to note that IL-6 expression is precisely regulated with TIMP-1 production at both protein and mRNA levels. The effect of TIMP-1 on IL-6 levels is more pronounced under hypoxic versus normoxic conditions. Importantly, IL-6 expression is upregulated by addition of exogenous human recombinant TIMP-1 in a time- and dose- dependent manner. Blocking of TIMP-1 signaling with specific neutralizing antibodies delayed the IL-6 upregulation. Moreover, addition of rhTIMP-1 or rhIL-6 rescued apoptosis induced by chemotherapeutic agents albeit to a limited extent. Although early in the investigation, our studies suggest that interventions impacting the TIMP-1/IL-6 axis in NSCLCs may provide an efficient target to boost effects of clinical chemotherapy. Citation Format: Wei Xiao, Amyn M. Rojiani, Sampa Ghoshal Gupta, Mumtaz V. Rojiani. Autocrine TIMP-1-mediated chemoresistance via induction of IL-6 in NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1974.