G Protein-Coupled Receptor 68 Promotes the Progression of Triple-Negative Breast Cancer and Cuproptosis Resistance...

Cuproptosis is a type of cell death that depends on the energy production process inside cells, and it is important in cancer treatment. This study aimed to identify cuproptosis-associated genes in triple-negative breast cancer (TNBC) and reveal regulatory pathways. We applied weighted gene co-expression network analysis to screen gene expression data from TNBC patients. Cuproptosis-associated genes were identified at the intersection of the co-expression modules and the cuproptosis gene dataset. G protein-coupled receptor 68 (GPR68) was identified as a cuproptosis-associated gene that is highly expressed in TNBC cells. Knockdown of GPR68 inhibited TNBC cell growth, migration, and invasion. The knockdown of GPR68 enhanced cuproptosis in TNBC cells when stimulated with ES-Cu, leading to an accumulation of cellular copper. This effect was reversed by the copper chelator tetrathiomolybdate. Correlation analysis verified that GPR68 regulates glutaminase (GLS) expression in TNBC cells. GLS knockdown reversed the promoted role of GPR68 in TNBC progression and the inhibitory role of GPR68 in TNBC cell cuproptosis. We further investigated the role of GPR68 in TNBC through pathway enrichment analysis, which revealed significant enrichment in the mitogen-activated protein kinase (MAPK) signaling pathway. GPR68 overexpression increased the levels of ERK phosphorylation. The ERK signaling pathway inhibitor, Trametinib, blocked the effects of GPR68 on TNBC progression and cuproptosis. GPR68 knockdown hindered TNBC development and induced cell cuproptosis by regulating the MEK/ERK signaling pathway, which is linked to GLS. This study provides new insights into developing cuproptosis targets for TNBC treatment.