A pathways-based approach identifying determinants of drug resistance in oesophageal adenocarcinoma

This identified the additive effect of combining dasatinib with cisplatin in an OAC setting. Src inhibition using dasatinib and saracatinib was assessed with MTT viability assays, assessing the efficacy of combining Src-inhibition with traditional chemotherapies. CI values were generated to assess synergy.

Western blotting, flow cytometry and high-content costaining was performed to investigate the mechanisms of action governing the synergistic effects identified. A model of cisplatin-resistance (OE33-CDDPR) was used to assess Src’s role in acquired resistance.<br><br>Results: <br>GSEA identified pathways associated with resistance to chemotherapy in OAC. Candidate genes were selected according to predefined criteria and 80 genes were taken forward in a siRNA screen to study the effects on cell viability of gene silencing alone or in combination with cisplatin/5-FU.

Twelve genes were found to have an additive effect with chemotherapy to improve chemo-efficacy across an OAC cell line panel, including SRC. A high-throughput drug screen highlighted a number of novel compounds that displayed additive effects when combined with cisplatin, including dasatinib, a Src inhibitor. Src was then validated in an in vitro OAC setting, investigating the effects of Src inhibition using siRNA, dasatinib and saracatinib.

In vitro combination experiments showed that combining Src inhibitors with traditional chemotherapies provides synergistic effects.<br><br>Conclusions:<br>Using a functional genomic approach we identified Src as a novel target associated with reduced cell viability following siRNA-mediated knockdown. By the use of small molecule inhibitors, we reinforced the results of the siRNA screen, verifying the clinical potential and synergistic effects of targeting Src alongside traditional chemotherapy treatments in a setting of OAC.