In both considered cell lines, non-small cell lung cancer and triple-negative breast cancer, the promoters of genes, which were not overexpressed in the cisplatin-resistant phenotype, were enriched in components of the CoREST repressive complex such as CoREST (RCOR1—REST corepressor 1) and enzymatically active subunits: HDAC1 and LSD1. This evidence concerns the gene RCOR1 and triple-negative breast carcinoma.