RNA sequencing of MDA-MB231 and U2OS cancer cell lines exposed to the alkylating agent methyl methanesufonate (MMS) and classical chemotherapeutics 

Understanding the mechanisms by which cells respond to chemotherapeutics is key to identifying means to improve therapy effiicacy while reducing systemic toxicity of these widely used classes of drugs. While determining the role of NRF2-GSH and ER stress in cells exposed to alkylating compounds such as methyl-methanesulfonate (MMS), we asked if these pathways could also be a general cell damage response relevant to other clinically used chemotherapeutics or if it is an alkylation specific response. With this intent, we performed RNA sequencing of MDA-MB231 breast cancer and U2OS osteosarcoma cells lines treated for 8 hours with a topoisomerase II inhibitor etoposide (20 µM), the antimitotic beta-tubulin-interacting drug paclitaxel (0.2 µM), doxorubicin (1 µM) and compared to MMS (40 µg/mL) treated cells. Doses represent IC50 level after 72 hours exposure. We observed that even though non-alkylating drugs, especially etoposide, caused an increase in the mRNA expression of some NRF2 and ER stress signaling markers, the number and magnitude of upregulation of genes markers in either pathway was more pronounced in alkylation treatments compared to other drugs. This indicates that alterations in NRF2 and ER stress pathways could be more likely associated with differential sensitivity to alkylating chemotherapies. Overall design: MDA-MB231 breast cancer and U2OS osteosarcoma cells lines were treated with the 72 h IC50  dose of etoposide (20 µM), paclitaxel (0.2 µM),  doxorubicin (1 µM) or  MMS (40 µg/mL) for 8 h, and RNA was extracted and analyzed.

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Zanotto-Filho A, Masamsetti VP, Loranc E, Tonapi SS, Gorthi A, Bernard X, Gonçalves RM, Moreira JC, Chen Y, Bishop AJ