RESUMO
Platinum resistance accounts for much of the high mortality and morbidity associated with ovarian cancer. Identification of targets with significant clinical translational potential remains an unmet challenge. Through a high-throughput synthetical lethal screening for clinically relevant targets using 290 kinase inhibitors, we identify calcium/calmodulin-dependent protein kinase II gamma (CAMK2G) as a critical vulnerability in cisplatin-resistant ovarian cancer cells. Pharmacologic inhibition of CAMK2G significantly sensitizes ovarian cancer cells to cisplatin treatment in vitro and in vivo. Mechanistically, CAMK2G directly senses ROS, both basal and cisplatin-induced, to control the phosphorylation of ITPKB at serine 174, which directly regulates ITPKB activity to modulate cisplatin-induced ROS stress. Thereby, CAMK2G facilitates the adaptive redox homeostasis upon cisplatin treatment and drives cisplatin resistance. Clinically, upregulation of CAMK2G activity and ITPKB pS174 correlates with cisplatin resistance in human ovarian cancers. This study reveals a key kinase network consisting of CAMK2G and ITPKB for ROS sense and scavenging in ovarian cancer cells to maintain redox homeostasis, offering a potential strategy for cisplatin resistance treatment.
Assuntos
CisplatinoRESUMO
PURPOSE: Although platinum compounds are the first-line treatment for ovarian cancer, the majority of patients relapse and develop resistance to treatment. However, the mechanism underlying resistance is unclear. The goal of our study is to decipher the mechanism by which a metabolic kinase, diacylglycerol kinase alpha (DGKA), confers platinum resistance in ovarian cancer. EXPERIMENTAL DESIGN: Metabolic kinase RNAi synthetic lethal screening was used to identify a cisplatin resistance driver in ovarian cancer. DGKA variants were used to demonstrate the need for DGKA activity in cisplatin resistance. Phospho-proteomic and genomic screens were performed to identify downstream effectors of DGKA. Therapeutic efficacy of targeting DGKA was confirmed and clinical relevance of DGKA signaling was validated using ovarian cancer patient-derived tumors that had different responses to platinum-based therapy. RESULTS: We found that platinum resistance was mediated by DGKA and its product, phosphatidic acid (PA), in ovarian cancer. Proteomic and genomic screens revealed that DGKA activates the transcription factor c-JUN and consequently enhances expression of a cell-cycle regulator, WEE1. Mechanistically, PA facilitates c-JUN N-terminal kinase recruitment to c-JUN and its nuclear localization, leading to c-JUN activation upon cisplatin exposure. Pharmacologic inhibition of DGKA sensitized ovarian cancer cells to cisplatin treatment and DGKA-c-JUN-WEE1 signaling positively correlated with platinum resistance in tumors derived from patients with ovarian cancer. CONCLUSIONS: Our study demonstrates how the DGKA-derived lipid messenger, PA, contributes to cisplatin resistance by intertwining with kinase and transcription networks, and provides preclinical evidence for targeting DGKA as a new strategy in ovarian cancer treatment to battle cisplatin resistance.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Cisplatino/farmacologia , Diacilglicerol Quinase/metabolismo , Resistencia a Medicamentos Antineoplásicos/genética , Neoplasias Ovarianas/tratamento farmacológico , Proteínas Proto-Oncogênicas c-jun/metabolismo , Idoso , Idoso de 80 Anos ou mais , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Núcleo Celular/metabolismo , Cisplatino/uso terapêutico , Diacilglicerol Quinase/antagonistas & inibidores , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Camundongos , Pessoa de Meia-Idade , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Ovário/patologia , Ácidos Fosfatídicos/metabolismo , Proteínas Tirosina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Microtubule-associated serine/threonine kinase 1 (MAST1) is a central driver of cisplatin resistance in human cancers. However, the molecular mechanism regulating MAST1 levels in cisplatin-resistant tumors is unknown. Through a proteomics screen, we identified the heat shock protein 90 B (hsp90B) chaperone as a direct MAST1 binding partner essential for its stabilization. Targeting hsp90B sensitized cancer cells to cisplatin predominantly through MAST1 destabilization. Mechanistically, interaction of hsp90B with MAST1 blocked ubiquitination of MAST1 at lysines 317 and 545 by the E3 ubiquitin ligase CHIP and prevented proteasomal degradation. The hsp90B-MAST1-CHIP signaling axis and its relationship with cisplatin response were clinically validated in cancer patients. Furthermore, combined treatment with a hsp90 inhibitor and the MAST1 inhibitor lestaurtinib further abrogated MAST1 activity and consequently enhanced cisplatin-induced tumor growth arrest in a patient-derived xenograft model. Our study not only uncovers the regulatory mechanism of MAST1 in tumors but also suggests a promising combinatorial therapy to overcome cisplatin resistance in human cancers.