Adam Kinnaird

A nuclear pyruvate dehydrogenase complex is important for the generation of acetyl-CoA and histone acetylation.

DNA transcription, replication, and repair are regulated by histone acetylation, a process that requires the generation of acetyl-coenzyme A (CoA). Here, we show that all the subunits of the mitochondrial pyruvate dehydrogenase complex (PDC) are also present and functional in the nucleus of mammalian cells. We found that knockdown of nuclear PDC in isolated functional nuclei decreased the de novo synthesis of acetyl-CoA and acetylation of core histones. Nuclear PDC levels increased in a cell-cycle-dependent manner and in response to serum, epidermal growth factor, or mitochondrial stress; this was accompanied by a corresponding decrease in mitochondrial PDC levels, suggesting a translocation from the mitochondria to the nucleus. Inhibition of nuclear PDC decreased acetylation of specific lysine residues on histones important for G1-S phase progression and expression of S phase markers. Dynamic translocation of mitochondrial PDC to the nucleus provides a pathway for nuclear acetyl-CoA synthesis required for histone acetylation and epigenetic regulation.

Metabolic control of epigenetics in cancer.

Alterations in the epigenome and metabolism both affect molecular rewiring in cancer cells and facilitate cancer development and progression. However, recent evidence suggests the existence of important bidirectional regulatory mechanisms between metabolic remodelling and the epigenome (specifically methylation and acetylation of histones) in cancer. Most chromatin-modifying enzymes require substrates or cofactors that are intermediates of cell metabolism. Such metabolites, and often the enzymes that produce them, can transfer into the nucleus, directly linking metabolism to nuclear transcription. We discuss how metabolic remodelling can contribute to tumour epigenetic alterations, thereby affecting cancer cell differentiation, proliferation and/or apoptosis, as well as therapeutic responses.

Stricture length and etiology as preoperative independent predictors of recurrence after urethroplasty: A multivariate analysis of 604 urethroplasties

INTRODUCTION We determine the preoperative identifiable risk factors during staging that predict stricture recurrence after urethroplasty. METHODS We conducted a retrospective review of all urethroplasties performed at a Canadian tertiary referral centre from 2003 to 2012. Failure was defined as a recurrent stricture <16 Fr on cystoscopic assessment. Multivariate analysis was calculated by Cox proportional hazard regression. RESULTS In total, 604 of 651 (93%) urethroplasties performed had adequate data with a mean follow-up of 52 months. Overall urethral patency was 90.7% with failures occurring between 2 weeks and 77 months postoperatively. The average time to recurrence was 11.7 months, with most patients with recurrence within 6 months (42/56; 75%). Multivariate regression identified Lichen sclerosus, iatrogenic, and infectious etiologies to be independently associated with stricture recurrence with hazard ratios (HR) (95% confidence interval) of 5.9 (2.1-16.5; p ≤ 0.001), 3.4 (1.2-10; p = 0.02), and 7.3 (2.3-23.7; p ≤ 0.001), respectively. Strictures ≥5cm recurred significantly more often (13.8% vs. 5.9%) with a HR 2.3 (1.2-4.5; p ≤ 0.01). Comorbidities, smoking, previous urethroplasty, stricture location and an age ≥50 were not associated with recurrence. CONCLUSION Urethroplasty in general is an excellent treatment for urethral stricture with patency rates approaching 91%. While recurrences occur over 6 years after surgery, most (75%) recur within the first 6 months. Long segment strictures (≥5 cm), as well as Lichen sclerosus, infectious and iatrogenic etiologies, are associated with increased risk of recurrence. Limitations include the retrospective, single-centre nature of the study and the 7% loss to follow-up due to the centre being a regional referral one.

Inhibition of pyruvate dehydrogenase kinase improves pulmonary arterial hypertension in genetically susceptible patients

Metabolic modulation with dichloroacetate improves hemodynamics in genetically susceptible patients with idiopathic pulmonary arterial hypertension. Progress for PAH In addition to thickening and occlusion of the pulmonary arteries, mitochondrial respiration is suppressed in pulmonary arterial hypertension (PAH). Michelakis et al. treated lungs from patients with PAH with dichloroacetate (DCA), a drug used to treat cancer and congenital mitochondrial disease that inhibits the mitochondrial enzyme pyruvate dehydrogenase kinase. DCA increased mitochondrial function; however, the response was variable, and this variable response was mirrored in a phase 1 trial, with some patients showing improved hemodynamics and functional capacity. The authors determined that patients with inactivating mutations in two genes encoding mitochondrial proteins were less responsive to DCA. This work highlights the importance of considering patient genotype in clinical trial design and identifies a drug target for PAH. Pulmonary arterial hypertension (PAH) is a progressive vascular disease with a high mortality rate. It is characterized by an occlusive vascular remodeling due to a pro-proliferative and antiapoptotic environment in the wall of resistance pulmonary arteries (PAs). Proliferating cells exhibit a cancer-like metabolic switch where mitochondrial glucose oxidation is suppressed, whereas glycolysis is up-regulated as the major source of adenosine triphosphate production. This multifactorial mitochondrial suppression leads to inhibition of apoptosis and downstream signaling promoting proliferation. We report an increase in pyruvate dehydrogenase kinase (PDK), an inhibitor of the mitochondrial enzyme pyruvate dehydrogenase (PDH, the gatekeeping enzyme of glucose oxidation) in the PAs of human PAH compared to healthy lungs. Treatment of explanted human PAH lungs with the PDK inhibitor dichloroacetate (DCA) ex vivo activated PDH and increased mitochondrial respiration. In a 4-month, open-label study, DCA (3 to 6.25 mg/kg b.i.d.) administered to patients with idiopathic PAH (iPAH) already on approved iPAH therapies led to reduction in mean PA pressure and pulmonary vascular resistance and improvement in functional capacity, but with a range of individual responses. Lack of ex vivo and clinical response was associated with the presence of functional variants of SIRT3 and UCP2 that predict reduced protein function. Impaired function of these proteins causes PDK-independent mitochondrial suppression and pulmonary hypertension in mice. This first-in-human trial of a mitochondria-targeting drug in iPAH demonstrates that PDK is a druggable target and offers hemodynamic improvement in genetically susceptible patients, paving the way for novel precision medicine approaches in this disease.

Metabolic Modulation of Clear-cell Renal Cell Carcinoma with Dichloroacetate, an Inhibitor of Pyruvate Dehydrogenase Kinase.

BACKGROUND Clear-cell renal cell carcinoma (ccRCC) exhibits suppressed mitochondrial function and preferential use of glycolysis even in normoxia, promoting proliferation and suppressing apoptosis. ccRCC resistance to therapy is driven by constitutive hypoxia-inducible factor (HIF) expression due to genetic loss of von Hippel-Lindau factor. In addition to promoting angiogenesis, HIF suppresses mitochondrial function by inducing pyruvate dehydrogenase kinase (PDK), a gatekeeping enzyme for mitochondrial glucose oxidation. OBJECTIVE To reverse mitochondrial suppression of ccRCC using the PDK inhibitor dichloroacetate (DCA). DESIGN, SETTING, AND PARTICIPANTS Radical nephrectomy specimens from patients with ccRCC were assessed for PDK expression. The 786-O ccRCC line and two animal models (chicken in ovo and murine xenografts) were used for mechanistic studies. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS Mitochondrial function, proliferation, apoptosis, HIF transcriptional activity, angiogenesis, and tumor size were measured in vitro and in vivo. Independent-sample t-tests and analysis of variance were used for statistical analyses. RESULTS PDK was elevated in 786-O cells and in ccRCC compared to normal kidney tissue from the same patient. DCA reactivated mitochondrial function (increased respiration, Krebs cycle metabolites such as α-ketoglutarate [cofactor of factor inhibiting HIF], and mitochondrial reactive oxygen species), increased p53 activity and apoptosis, and decreased proliferation in 786-O cells. DCA reduced HIF transcriptional activity in an FIH-dependent manner, inhibiting angiogenesis in vitro. DCA reduced tumor size and angiogenesis in vivo in both animal models. CONCLUSIONS DCA can reverse the mitochondrial suppression of ccRCC and decrease HIF transcriptional activity, bypassing its constitutive expression. Its previous clinical use in humans makes it an attractive candidate for translation to ccRCC patients. PATIENT SUMMARY We show that an energy-boosting drug decreases tumor growth and tumor blood vessels in animals carrying human kidney cancer cells. This generic drug has been used in patients for other conditions and thus could be tested in kidney cancer that remains incurable.

Revision Urethroplasty Success Is Comparable to Primary Urethroplasty: A Comparative Analysis

OBJECTIVE To assess the efficacy and complications of revision urethroplasty compared with urethroplasty-naïve controls. MATERIALS AND METHODS A retrospective analysis was performed of 534 urethroplasties performed by a single surgeon from August 2003 to March 2011. Patient age, stricture length, location, etiology, comorbidities, and type of surgery were recorded. Statistical comparison between the revision cohort and urethroplasty-naïve group were made using Fisher, χ(2), and unpaired t tests, with significance at P < .05 (2-tailed). The primary outcome was urethral patency assessed by cystoscopy. Secondary (subjective) outcome measures included erectile dysfunction, pain, urinary tract infection, or chordee at 6 months. RESULTS A total of 476 patients met inclusion criteria with completed cystoscopic follow-up. Previous urethroplasty had failed in 49 patients (10.3%). Patients undergoing revision urethroplasty were more likely to have stricture in the penile urethra (22.4%; P = .001), to have strictures exceeding 4 cm in length (71.4% vs 54.3%; P = .023), and to require tissue transfer (83.6% vs 65.1%; P = .010). Urethral patency rates did not differ significantly between naïve and revision urethroplasty cohorts, with a mean follow-up of 49.9 months (94.6% vs 91.8%; P = .518). The revision group had a higher incidence of chordee (2.7% vs 14.3%; P = .001) and urinary tract infection (3.5% vs 10.2%; P = .04). The rates of erectile dysfunction, scrotal pain, lower urinary tract symptoms, and incontinence did not differ significantly between the 2 groups. CONCLUSION Revision urethroplasty is an effective treatment option for recurrent stricture after urethroplasty and is comparable to results in urethroplasty-naïve patients. Patients undergoing revision urethroplasty are more likely to require tissue transfer and experience higher rates of chordee and urinary tract infection.

Independent Predictors of Stricture Recurrence Following Urethroplasty for Isolated Bulbar Urethral Strictures

Purpose: We evaluated preoperative risk factors associated with stricture recurrence in a large, homogenous series of bulbar urethroplasties. Materials and Methods: We analyzed the records of 596 patients who underwent isolated bulbar urethroplasty at a single center from August 2003 to June 2015. Urethroplasty failure was defined as stricture less than 16Fr identified on cystoscopy with a minimum of 12 months of followup. The potential risk factors examined were patient age, stricture etiology, stricture length, diabetes, smoking, obesity, Charlson comorbidity index, previous endoscopic treatment, previous urethroplasty and type of urethroplasty. Univariate and multivariable Cox regression analysis was used to evaluate potential risk factors and associations. Results: Average stricture length was 3.9 cm and mean patient age was 44.4 years. Overall urethral patency was 93.3% and mean followup was 65.4 months (range 12 to 149). Previous endoscopic treatment had failed in 88.1% of patients while previous urethroplasty had failed in 10.7%. On multivariate analysis increased stricture length (HR 1.2, 95% CI 1.1–1.3, p = 0.01), increased patient comorbidity (HR 2.4, 95% CI 1.1–5.3, p = 0.03), obesity (HR 2.9, 95% CI 1.3–6.5, p = 0.01) and infectious strictures (HR 3.7, 95% CI 1.3–10.6, p = 0.02) were associated with stricture recurrence. Previous urethroplasty, the number of failed endoscopic procedures, type of urethroplasty and individual comorbidities such as diabetes, smoking and patient age did not affect the recurrent stricture rate. Conclusions: Although bulbar urethroplasty has a good stricture‐free rate, patients with increased stricture length, increased overall comorbidity, obesity and strictures of infectious etiology are at higher risk for failure. These patients at risk should be counseled accordingly and perhaps be followed more closely after urethroplasty.

Zero ischemia robotic-assisted partial nephrectomy in Alberta: Initial results of a novel approach

INTRODUCTION Partial nephrectomy remains the standard of care in early stage, organ-confined renal tumours. Recent evidence suggests that minimally invasive surgery can proceed without segmental vessel clamping. In this study, we review our experience at a Canadian centre with zero ischemia robotic-assisted partial nephrectomy (RAPN). METHODS A retrospective chart review of zero ischemia RAPN was performed. All surgeries were consecutive partial nephrectomies performed by the same surgeon at a tertiary care centre in Northern Alberta. The mean follow-up period was 28 months. These outcomes were compared against the current standards for zero ischemia (as outlined by the University of Southern California Institute of Urology [USC]). RESULTS We included 21 patients who underwent zero ischemia RAPN between January 2012 and June 2013. Baseline data were similar to contemporary studies. Twelve (57.1%) required no vascular clamping, 7 (33.3%) required clamping of a single segmental artery, and 2 (9.5%) required clamping of two segmental arteries. We achieved an average estimated blood loss of 158 cc, with a 9.2% average increase in creatinine postoperatively. Operating time and duration of hospital stay were short at 153 minutes and 2.2 days, respectively. CONCLUSION Zero ischemia partial nephrectomy was a viable option at our institution with favourable results in terms of intra-operative blood loss and postoperative creatinine change compared to results from contemporary standard zero ischemia studies (USC). To our knowledge, this is the first study to review an initial experience with the zero ischemia protocol in robotic-assisted partial nephrectomies at a Canadian hospital.

Non-Transecting Techniques Reduce Sexual Dysfunction After Anastomotic Bulbar Urethroplasty: Results of a Multi-Institutional Comparative Analysis

Purpose: The purpose of this multi-institutional study was to compare outcomes of transecting and nontransecting anastomotic bulbar urethroplasty. Materials and Methods: We performed a retrospective, multi-institutional review of the records of 352 patients who underwent transecting or nontransecting anastomotic bulbar urethroplasty performed by 1 of 4 reconstructive urologists from September 2003 to March 2017. Study outcomes were urethroplasty success, defined as urethral patency greater than 16Fr on cystoscopy; de novo sexual dysfunction assessed at 6 months, defined as a 5-point or greater change in the SHIM (Sexual Health Inventory for Men) or a patient reported adverse change; and 90-day complications, defined as Clavien 2 or greater. When appropriate, comparisons were made between the transecting and nontransecting cohorts using the Mantel-Cox test, the t-test or the chi-square test. Results: Of the 352 patients with a mean stricture length of 1.7 cm (range 0.5 to 5) 258 and 94 underwent transecting and nontransecting anastomotic bulbar urethroplasty, respectively. The overall success rate was 94.9% at a mean followup of 64.2 months (range 6 to 170). Of the patients 7.1% experienced a 90-day complication and 11.6% reported sexual dysfunction. When comparing transecting and nontransecting techniques, there was no difference in success (93.8% vs 97.9%, Mantel-Cox test p = 0.18) or postoperative complications (8.1% vs 4.3%, p = 0.25). Patients treated with transecting anastomotic urethroplasty were more likely to report an adverse change in sexual function (14.3% vs 4.3%, p = 0.008). On multivariate analysis only transecting urethroplasty was associated with sexual dysfunction (p = 0.01) while age (p = 0.29), stricture length (p = 0.42), etiology (p = 0.99) and surgeon (p = 0.88) were not. Conclusions: Anastomotic urethroplasty is a highly effective surgery with relatively minimal associated morbidity. Nontransecting anastomotic urethroplasty compares quite favorably to the transecting technique and likely reduces the risk of associated sexual dysfunction.

Recurrence and upstaging rates of T1 high-grade urothelial carcinoma of the bladder on repeat resection in a Canadian, resource-limited, healthcare system

INTRODUCTION Non-muscle-invasive bladder cancer is the most expensive malignancy to treat. Current Canadian guidelines recommend repeat transurethral resection of bladder tumour (TURBT) within six weeks after initial resection of T1 high-grade (T1HG) urothelial carcinoma, prior to initiation of intravesical bacillus Calmette-Guerin treatment. This is a burden on operating room usage and adds further cost and risk of complications. Internationally, major cancer centres report significant rates of recurrence and upstaging on repeat resection, however, minimal Canadian data is available. We aimed to determine the rate of recurrence and upstaging in a resource-limited, Canadian healthcare system. METHODS A retrospective review of patients receiving TURBT between November 2009 and November 2014 was performed. Patients were included if they had all three of the following: a pathological diagnosis of T1HG, adequate muscularis propria present in the specimen, and a repeat resection. RESULTS We reviewed 3166 patients who underwent TURBT and found 173 to meet our inclusion criteria. The overall recurrence and upstaging rates were 57.2% and 9.2%, respectively. Tumour recurrence and upstaging occurred more often in patients who had repeat resection after 12-24 weeks compared to those patients whose repeat resection occurred within 12 weeks. CONCLUSIONS Although recurrence rates are similar, we have found upstaging rates to be three- to four-fold lower than those previously reported. Despite this, one in 10 patients will be upstaged, justifying use of this resource within our healthcare system. Finally, timely repeat resection, within 12 weeks appears to be associated with preventing disease progression.