Investigating the phosphinic acid tripeptide mimetic DG013A as a tool compound inhibitor of the M1-aminopeptidase ERAP1

ERAP1 is a zinc-dependent M1-aminopeptidase that trims lipophilic amino acids from the N-terminus of peptides. Owing to its importance in the processing of antigens and regulation of the adaptive immune response, dysregulation of the highly polymorphic ERAP1 has been implicated in autoimmune disease and cancer. To test this hypothesis and establish the role of ERAP1 in these disease areas, high affinity, cell permeable and selective chemical probes are essential. DG013A 1, is a phosphinic acid tripeptide mimetic inhibitor with reported low nanomolar affinity for ERAP1. However, this chemotype is a privileged structure for binding to various metal-dependent peptidases and contains a highly charged phosphinic acid moiety, so it was unclear whether it would display the high selectivity and passive permeability required for a chemical probe. Therefore, we designed a new stereoselective route to synthesize a library of DG013A 1 analogues to determine the suitability of this compound as a cellular chemical probe to validate ERAP1 as a drug discovery target.

V-ATPase Inhibition Decreases Mutant Androgen Receptor Activity in Castrate-resistant Prostate Cancer

Prostate cancer is critically dependent on androgen receptor (AR) signaling. Despite initial responsiveness to androgen deprivation, most patients with advanced prostate cancer subsequently progress to a clinically aggressive castrate-resistant prostate cancer (CRPC) phenotype, typically associated with expression of splice-variant or mutant AR forms. Although current evidence suggests that the vacuolar-ATPase (V-ATPase), a multiprotein complex that catalyzes proton transport across intracellular and plasma membranes, influences wild-type AR function, the effect of V-ATPase inhibition on variant AR function is unknown.Inhibition of V-ATPase reduced AR function in wild-type and mutant AR luciferase reporter models. In hormone-sensitive prostate cancer cell lines (LNCaP, DuCaP) and mutant AR CRPC cell lines (22Rv1, LNCaP-F877L/T878A), V-ATPase inhibition using bafilomycin-A1 and concanamycin-A reduced AR expression, and expression of AR target genes, at mRNA and protein levels. Furthermore, combining chemical V-ATPase inhibition with the AR antagonist enzalutamide resulted in a greater reduction in AR downstream target expression than enzalutamide alone in LNCaP cells. To investigate the role of individual subunit isoforms, siRNA and CRISPR-Cas9 were used to target the V1C1 subunit in 22Rv1 cells. Whereas transfection with ATP6V1C1-targeted siRNA significantly reduced AR protein levels and function, CRISPR-Cas9-mediated V1C1 knockout showed no substantial change in AR expression, but a compensatory increase in protein levels of the alternate V1C2 isoform.Overall, these results indicate that V-ATPase dysregulation is directly linked to both hormone-responsive prostate cancer and CRPC via impact on AR function. In particular, V-ATPase inhibition can reduce AR signaling regardless of mutant AR expression.

Vacuolar ATPase as a potential therapeutic target and mediator of treatment resistance in cancer

Vacuolar ATPase (V-ATPase) is an ATP-dependent H+ -transporter that pumps protons across intracellular and plasma membranes. It consists of a large multi-subunit protein complex and influences a wide range of cellular processes. This review focuses on emerging evidence for the roles for V-ATPase in cancer. This includes how V-ATPase dysregulation contributes to cancer growth, metastasis, invasion and proliferation, and the potential link between V-ATPase and the development of drug resistance.

HIV-testing of men who have sex with men: variable testing rates among clinicians

High HIV testing coverage of high-risk populations is required to reduce the number of HIV-infected individuals unaware of their status. The aim of this study was to determine HIV testing rates among men who have sex with men (MSM) attending a sexual health service, including the impact of the treating clinician on HIV testing rates. Factors associated with HIV testing of MSM attending the Melbourne Sexual Health Centre for the first time between 2003 and 2009 were determined, including testing rates for individual treating clinicians. Overall, 78% of 4425 men were tested for HIV. Clinician HIV testing rates were higher among nurses (median 89%; range 77–95%) than doctors (median 73%; range 45–88%) with significant differences between individual physicians ( P < 0.001). Lower testing among doctors was independent of reported sexual risk and time since the last HIV test. Substantial differences in HIV testing rates between clinicians were evident with low testing by some. Increasing HIV testing rates among high-risk groups require engagement not only of individuals at risk but also awareness among health-care providers who perform HIV testing.

Evaluation of a self-help manual for media-recruited problem drinkers: six-month follow-up results

A total of 785 individuals responded to a newspaper advertisement offering free help to cut down drinking and were sent alternately either a self-help manual based on behavioural principles or a general information and advice booklet. Of these, 247 (31.3 per cent) returned assessment questionnaires or agreed to be interviewed by telephone and 132 of these respondents (53.4 per cent) were successfully contacted at six-month follow-up. Those lost to follow-up were more 'socially stable' on initial measures than those successfully contacted. Results showed a greater reduction in previous week's consumption in the group receiving the manual than in the control group. In addition, respondents interviewed by telephone showed a greater reduction on a measure of alcohol-related problems and a higher proportion reducing drinking than those contacted only by post. There was no evidence that reductions in consumption were confined to relatively low consumers or to those showing only early signs of dependence on alcohol, irrespective of which type of material was received.