RT Journal Article SR Electronic T1 Systematic screening reveals synergistic interactions that overcome MAPK inhibitor resistance in cancer cells JF Cancer Biology & Medicine JO Cancer Biol Med FD China Anti-Cancer Association SP 229 OP 252 DO 10.20892/j.issn.2095-3941.2020.0560 VO 19 IS 2 A1 Yu Yu A1 Minzhen Tao A1 Libin Xu A1 Lei Cao A1 Baoyu Le A1 Na An A1 Jilin Dong A1 Yajie Xu A1 Baoxing Yang A1 Wei Li A1 Bing Liu A1 Qiong Wu A1 Yinying Lu A1 Zhen Xie A1 Xiaohua Lian YR 2022 UL http://www.cancerbiomed.org/content/19/2/229.abstract AB Objective Effective adjuvant therapeutic strategies are urgently needed to overcome MAPK inhibitor (MAPKi) resistance, which is one of the most common forms of resistance that has emerged in many types of cancers. Here, we aimed to systematically identify the genetic interactions underlying MAPKi resistance, and to further investigate the mechanisms that produce the genetic interactions that generate synergistic MAPKi resistance.Methods We conducted a comprehensive pair-wise sgRNA-based high-throughput screening assay to identify synergistic interactions that sensitized cancer cells to MAPKi, and validated 3 genetic combinations through competitive growth, cell viability, and spheroid formation assays. We next conducted Kaplan-Meier survival analysis based on The Cancer Genome Atlas database and conducted immunohistochemistry to determine the clinical relevance of these synergistic combinations. We also investigated the MAPKi resistance mechanisms of these validated synergistic combinations by using co-immunoprecipitation, Western blot, qRT-PCR, and immunofluorescence assays.Results We constructed a systematic interaction network of MAPKi resistance and identified 3 novel synergistic combinations that effectively targeted MAPKi resistance (ITGB3 + IGF1R, ITGB3 + JNK, and HDGF + LGR5). We next analyzed their clinical relevance and the mechanisms by which they sensitized cancer cells to MAPKi exposure. Specifically, we discovered a novel protein complex, HDGF-LGR5, that adaptively responded to MAPKi to enhance cancer cell stemness, which was up- or downregulated by the inhibitors of ITGB3 + JNK or ITGB3 + IGF1R.Conclusions Pair-wise sgRNA library screening provided systematic insights into elucidating MAPKi resistance in cancer cells. ITGB3-+ IGF1R-targeting drugs (cilengitide + linsitinib) could be used as an effective therapy for suppressing the adaptive formation of the HDGF-LGR5 protein complex, which enhanced cancer stemness during MAPKi stress.