Gene Expression Analysis of Melanoma Cells Treated with 6-Thio-dG In Vitro

Telomerase promoter mutations are highly prevalent in human tumors including melanoma. Telomere transcriptional signatures are enriched in a subset of therapy-naïve melanomas associated with worse overall survival, in BRAF-mutant intrinsically resistant melanoma cells that evade MAPK inhibitors (MAPKi), as well as in a subset of post-treatment tumor biopsies derived from patients who have disease progression on MAPKi or the immune checkpoint inhibitors, anti-CTLA-4 or anti-PD1. We demonstrate the efficacy of a telomerase-directed nucleoside, 6-thio-2'-deoxyguanosine (6-thio-dG) that results in telomere dysfunction and cell death in various models of therapy-resistant cells. Furthermore, 6-thio-dG significantly inhibits tumor growth of primary tumor biopsy cultures derived from patients who had disease progression on multiple therapies including anti-CTLA-4 or anti-PD1. Overall design: A375 and LOX-IMVI BR melanoma cells were treated with the control, 6-Thio-dG and BIBR 1532. RNA was purified from two biological replicates for RNA sequencing.