ABSTRACT
RUVBL1 and RUVBL2 (collectively RUVBL1/2) are essential AAA+ ATPases that function as co-chaperones and have been implicated in cancer. Here we investigated the molecular and phenotypic role of RUVBL1/2 ATPase activity in non-small cell lung cancer (NSCLC). We find that RUVBL1/2 are overexpressed in NSCLC patient tumors, with high expression associated with poor survival. Utilizing a specific inhibitor of RUVBL1/2 ATPase activity, we show that RUVBL1/2 ATPase activity is necessary for the maturation or dissociation of the PAQosome, a large RUVBL1/2-dependent multiprotein complex. We also show that RUVBL1/2 have roles in DNA replication, as inhibition of its ATPase activity can cause S-phase arrest, which culminates in cancer cell death via replication catastrophe. While in vivo pharmacological inhibition of RUVBL1/2 results in modest antitumor activity, it synergizes with radiation in NSCLC, but not normal cells, an attractive property for future preclinical development.
Subject(s)
ATPases Associated with Diverse Cellular Activities/metabolism , Carcinoma, Non-Small-Cell Lung/metabolism , Carrier Proteins/metabolism , DNA Helicases/metabolism , DNA Replication , Lung Neoplasms/metabolism , Multiprotein Complexes/metabolism , ATPases Associated with Diverse Cellular Activities/antagonists & inhibitors , ATPases Associated with Diverse Cellular Activities/genetics , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Carcinoma, Non-Small-Cell Lung/diagnosis , Carcinoma, Non-Small-Cell Lung/drug therapy , Carrier Proteins/antagonists & inhibitors , Carrier Proteins/genetics , DNA Helicases/antagonists & inhibitors , DNA Helicases/genetics , DNA Replication/drug effects , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Humans , Lung Neoplasms/diagnosis , Lung Neoplasms/drug therapy , Molecular Structure , Multiprotein Complexes/antagonists & inhibitors , Multiprotein Complexes/genetics , Radiation ToleranceABSTRACT
Aging and female sex are the strongest risk factors for nontraumatic osteoarthritis (OA); whereas obesity is a modifiable risk factor accelerating OA. Prior studies indicate that the innate immune receptor toll-like receptor 4 (TLR4) mediates obesity-induced metabolic inflammation and cartilage catabolism via recognition of damage-associated molecular patterns and is increased with aging in OA joints. TLR4 responses are limited by innate immunoreceptor adapter protein DNAX-activating protein of 12kDA (DAP12). We undertook this study to test the hypothesis that TLR4 promotes, whereas DAP12 limits, obesity-accelerated OA in aged female mice. We fed 13- to 15-month-old female WT, TLR4 KO, and DAP12 KO mice a high-fat diet (HFD) or a control diet for 12 weeks, and changes in body composition, glucose tolerance, serum cytokines, and insulin levels were compared. Knee OA was evaluated by histopathology and µCT. Infrapatellar fat pads (IFPs) were analyzed by histomorphometry and F4/80+ crown-like structures were quantified. IFPs and synovium gene expression were analyzed using a targeted insulin resistance and inflammation array. All HFD-treated mice became obese, but only WT and TLR4 KO mice developed glucose intolerance. HFD induced cartilage catabolism in WT and DAP12 KO female mice, but not in TLR4 KO mice. Gene-expression analysis of IFPs and synovium showed significant differences in insulin signaling, adipokines, and inflammation between genotypes and diets. Unlike young mice, systemic inflammation was not induced by HFD in the older female mice independent of genotype. Our findings support the conclusion that TLR4 promotes and DAP12 limits HFD-induced cartilage catabolism in middle-aged female mice.
