Adaptive resistance of melanoma cells to RAF inhibition via reversible induction of a slowly dividing de-differentiated state

January 9, 2017

tion plates and a Seiko pin transfer robot system. Immediately after, A375 and WM115 cells were then treated with 1 μM vemurafenib and COLO858 cells were treated with 0.32 μM vemurafenib using an HP D300 Digital Dispenser. Forty‐eight hours after treatment, cells were fixed and analyzed for NGFR expression using immunofluorescence microscopy, as described earlier. To identify candidate compo;tion plates and a Seiko pin transfer robot system. Immediately after, A375 and WM115 cells were then treated with 1 μM vemurafenib and COLO858 cells were treated with 0.32 μM vemurafenib using an HP D300 Digital Dispenser. Forty‐eight hours after treatment, cells were fixed and analyzed for NGFR expression using immunofluorescence microscopy, as described earlier. To identify candidate compo

Treatment of BRAF-mutant melanomas with MAP kinase pathway inhibitors is paradigmatic of the promise of precision cancer therapy but also highlights problems with drug resistance that limit patient benefit. We use live-cell imaging, single-cell analysis, and molecular profiling to show that exposure of tumor cells to RAF/MEK inhibitors elicits a heterogeneous response in which some cells die, some arrest, and the remainder adapt to drug. Drug-adapted cells up-regulate markers of the neural crest (e.g., NGFR), a melanocyte precursor, and grow slowly. This phenotype is transiently stable, reverting to the drug-naïve state within 9 days of drug withdrawal. Transcriptional profiling of cell lines and human tumors implicates a c-Jun/ECM/FAK/Src cascade in de-differentiation in about one-third of cell lines studied; drug-induced changes in c-Jun and NGFR levels are also observed in xenograft and human tumors. Drugs targeting the c-Jun/ECM/FAK/Src cascade as well as BET bromodomain inhibitors increase the maximum effect (Emax) of RAF/MEK kinase inhibitors by promoting cell killing. Thus, analysis of reversible drug resistance at a single-cell level identifies signaling pathways and inhibitory drugs missed by assays that focus on cell populations. Š 2017 The Authors. Published under the terms of the CC BY 4.0 license.

Fallahi-Sichani, M; Becker, V; Izar, B; Baker, GJ; Lin, JR; Boswell, SA; Shah, P; Rotem, A; Garraway, LA; Sorger, PK;

Journal: Mol. Syst. Biol. Pages: 905

Original article (28069687)