Role of mTORC2 and Nitric oxide in Bladder Cancer Invasion

Abstract

BackgroundDespite accounting for around 17,000 deaths and 79,000 new diagnoses annually in the United States, treatment options for bladder cancer remain limited. The key driver of bladder cancer stage progression is increasing invasion into the bladder wall, which has limited response to current chemotherapy options and hence newer therapies directed against invasion are key to improving the treatment of bladder cancer. We have recently shown that arginine, the nitric oxide (NO) precursor, is implicated in bladder cancer progression. Our laboratory has also identified mammalian target of rapamycin complex 2 (mTORC2) as a driver of bladder cancer cell invasion. We evaluated the interaction between these two pathways to promote invasion.MethodsExpression of inducible and endothelial nitric oxide synthases (iNOS and eNOS) in FFPE tissue sections of progressive disease was assessed by IHC and correlated with histopathology, progression and stage based on moderate to strong expression (2+, 3+) compared to absent to weak expression (0, 1+). We utilized gene silencing methods and NOS inhibitors and NO scavenger for effects on bladder cancer invasion and migration. We assessed mTORC2 pathway activity and NOS levels in invasive cell tip protrusions called “invadopodia” and evaluated if mTORC2 regulates NOS localization. We used a novel zebrafish model to characterize the effects of mTORC2 and NO on bladder cancer metastases.ResultWe found that eNOS and iNOS are elevated in invasive human bladder tumors and cell lines and their ablation reduces bladder cancer cell migration and invasion by reorganizing the actin cytoskeleton and reducing invadopodia. mTORC2 silencing can affect levels of iNOS and eNOS in bladder cancer cell lines. Silencing of mTORC2, eNOS or iNOS reduced metastases of bladder cancer cells within zebrafish.ConclusionmTORC2 pathway is a key driver of bladder cancer invasion and metastases by regulating the NO pathway and both mTORC2 and NO can be targets for bladder cancer therapy, which would benefit patient outcomes.Support or Funding InformationPrevent Cancer Foundation Fellowship to DSCase Western Reserve University/Cleveland Clinic CTSA Grant Number UL1 RR024989 from the National Center for Research Resources (NCRR), a KL2 career development award (RR024990) and UCSD start‐up funding to DEHThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.