GSE135514
Transcriptomic insight into salinomycin mechanisms in breast cancer cell lines: synergistic effects with dasatinib and induction of estrogen receptor beta
Purpose:The use of a single-drug to encounter cancer progression is generally ineffective due to the tumors heterogeneity. To improve the clinical outcome, multiple drugs of distinctive mechanisms but complementary anticancer activities (combination therapy) are often used to enhance antitumor efficacy and minimize the risk of acquiring drug resistance. In this study, we proposed to use a combination of salinomycin (which targets anticancer stem cells) and dasatinib (an Src kinase inhibitor) for the treatment of breast cancer. The use of a RNA-seq is a combinatorial technique that allows to quantify global gene expression in biological samples. We employed this next generation sequencing technique to provide an initial insight into how Sal and Das alone, as well as in combination, modulated gene expression in the MDA-MB-468 human triple negative breast cancer cell line. Method: mRNA profiles of MDA-MB-468 cells treated with PBS (control), salinomycin, dasatinib, or the drug combination Sal + Das were generated by deep sequencing, in quadruplicate, using HiSeq4000 sequencer with single-end 50 bps reads. The results were validated by RT-qPCR analysis using StepOnePlus Real-timePCR system and SYBR Green assays. Results: RNA-seq data revealed that both salinomycin and dasatinib inhibit the expression of many downstream targeted genes of the STAT3, Wnt/beta-catenin, and hedgehog cell signaling pathways. The drug combination exhibited synergism through suppression of multiple pathways, leading to a promotion of cell cycle arrest at the G1/S phase mainly via the estrogen-mediated S-phase entry pathway, and partially via the BRCA1 and DNA damage response pathway. We also identified new salinomycin mechanisms involved in upregulating transcription factor 2. The study further led to a discovery of a new drug-induced targeting of estrogen receptor beta approach for triple-negative breast cancer treatment. Conclusion: Using RNA-seq, we identified for the first time the responsible pathways, including the estrogen-mediated S-phase entry pathway, that contributed to the synergistic effects of the drug combination Sal + Das. The discoveries of potential therapeutic targets, such as E2F2 as well as a novel drug-induced targeting of estrogen receptor beta (ESR2) approach were also described herein.We believe that using next generation approach to study drug mechanisms will allow us to identify more specific disease-relevant biomarkers for precision treatment of breast cancer, as well as other cancers in the future. Overall design: mRNA profiles of MDA-MB-468 cells treated with PBS (control), salinomycin, dasatinib, or the drug combination Sal + Das were generated by deep sequencing, in quadruplicate, using HiSeq4000 sequencer with single-end 50 bps reads.