Syntaxin 6-mediated exosome secretion regulates enzalutamide resistance in prostate cancer.

Prostate cancer (PCa) deaths are typically the result of metastatic castration-resistant PCa (mCRPC). Recently, enzalutamide (Enz), an oral androgen receptor inhibitor, was approved for treating patients with mCRPC. Invariably, all PCa patients eventually develop resistance against Enz. Therefore, novel strategies aimed at overcoming Enz resistance are needed to improve the survival of PCa patients. The role of exosomes in drug resistance has not been fully elucidated in PCa. Therefore, we set out to better understand the exosome's role in the mechanism underlying Enz-resistant PCa. Results showed that Enz-resistant PCa cells (C4-2B, CWR-R1, and LNCaP) secreted significantly higher amounts of exosomes (2-4 folds) compared to Enz-sensitive counterparts. Inhibition of exosome biogenesis in resistant cells by GW4869 and dimethyl amiloride strongly decreased their cell viability. Mechanistic studies revealed upregulation of syntaxin 6 as well as its increased colocalization with CD63 in Enz-resistant PCa cells compared to Enz-sensitive cells. Syntaxin 6 knockdown by specific small interfering RNAs in Enz-resistant PCa cells (C4-2B and CWR-R1) resulted in reduced cell number and increased cell death in the presence of Enz. Furthermore, syntaxin 6 knockdown significantly reduced the exosome secretion in both Enz-resistant C4-2B and CWR-R1 cells. The Cancer Genome Atlas analysis showed increased syntaxin 6 expressions associated with higher Gleason score and decreased progression-free survival in PCa patients. Importantly, IHC analysis showed higher syntaxin 6 expression in cancer tissues from Enz-treated patients compared to Enz naïve patients. Overall, syntaxin 6 plays an important role in the secretion of exosomes and increased survival of Enz-resistant PCa cells.

A National Cancer Database-based nomogram to predict lymph node metastasis in penile cancer.

OBJECTIVE: To evaluate the predictive nature of several clinicopathological variables by developing a nomogram predictive for lymph node-positive disease using the National Cancer Database cohort of patients with squamous cell carcinoma of the penis. METHODS: Stepwise logistic regression was used to find the best-fit model; remaining clinical variables were used to create a nomogram to predict the probability of lymph node-positive disease. RESULTS: On multivariate analysis, high pathological grade (3-4 vs 1: odds ratio [OR] 3.27, 95% confidence interval [CI] 1.70-6.29; 2 vs 1: OR 2.58, 95% CI 1.39-4.79 [P = 0.002]), lymphovascular invasion (OR 2.49, 95% CI 1.61-3.84 [P < 0.001]), and positive clinical lymph node status (N1 vs N0: OR 20.0, 95% CI 11.4-35.7; N2 vs N0: OR 27.8, 95% CI 14.1-55.6; N3 vs N0: OR 49.2, 95% CI 14.8-162.8 [P < 0.001]) were predictors of lymph node metastasis in penile cancer. The bootstrap-corrected concordance index of this nomogram was 0.880. CONCLUSION: Using tumour grade, tumour lymphovascular invasion and clinical lymph node status, we developed a nomogram highly predictive of pathologial lymph node metastasis that, after further external validation, could be helpful in the surgical decision-making process.

Exosomes secreted by placental stem cells selectively inhibit growth of aggressive prostate cancer cells.

The current paradigm in the development of new cancer therapies is the ability to target tumor cells while avoiding harm to noncancerous cells. Furthermore, there is a need to develop novel therapeutic options against drug-resistant cancer cells. Herein, we characterized the placental-derived stem cell (PLSC) exosomes (PLSCExo) and evaluated their anti-cancer efficacy in prostate cancer (PCa) cell lines. Nanoparticle tracking analyses revealed the size distribution (average size 131.4 ±â€¯0.9 nm) and concentration of exosomes (5.23 × 1010±1.99 × 109 per ml) secreted by PLSC. PLSCExo treatment strongly inhibited the viability of enzalutamide-sensitive and -resistant PCa cell lines (C4-2B, CWR-R1, and LNCaP cells). Interestingly, PLSCExo treatment had no effect on the viability of a non-neoplastic human prostate cell line (PREC-1). Mass spectrometry (MS) analyses showed that PLSCExo are loaded with 241 proteins and mainly with saturated fatty acids. Further, Ingenuity Pathway Analysis analyses of proteins loaded in PLSCExo suggested the role of retinoic acid receptor/liver x receptor pathways in their biological effects. Together, these results suggest the novel selective anti-cancer effects of PLSCExo against aggressive PCa cells.

Adipose Tissue-Derived Stem Cells for the Treatment of Erectile Dysfunction.

Although a spectrum of options is available for erectile dysfunction (ED) treatment, ED in diabetics, post-prostatectomy patients, and those with Peyronie's disease (PD) may be more severe in degree and less likely to respond to conventional medical therapies. Unfortunately, there have been limited breakthroughs in therapeutic options for severe ED during the past decade. However, one of the more fascinating strategies in preclinical development to treat ED is stem cell transplantation. Depending on the cell type, recent research has demonstrated that with transplantation, these stem cells can exert a paracrine effect on surrounding penile tissues and differentiate into smooth muscle, endothelium, and neurons. Adipose tissue-derived stem cells (ADSCs) have become a valuable resource because of their abundance and ease of isolation. It is evident that ADSCs may provide a realistic, therapeutic modality for the treatment of ED. In this review, we will cover the literature that has evaluated ADSCs in the treatment of ED.

Analysis of erectile responses to H2S donors in the anesthetized rat.

Hydrogen sulfide (H2S) is a biologically active endogenous gasotransmitter formed in penile tissue that has been shown to relax isolated cavernosal smooth muscle. In the present study, erectile responses to the H2S donors sodium sulfide (Na2S) and sodium hydrosulfide (NaHS) were investigated in the anesthetized rat. Intracavernosal injections of Na2S in doses of 0.03-1 mg/kg increased intracavernosal pressure and transiently decreased mean arterial pressure in a dose-dependent manner. Blood pressure responses to Na2S were rapid in onset and short in duration. Responses to Na2S and NaHS were similar at doses up to 0.3 mg/kg, after which a plateau in the erectile response to NaHS was reached. Increases in intracavernosal pressure in response to Na2S were attenuated by tetraethylammonium (K(+) channel inhibitor) and iberiotoxin (large-conductance Ca(2+)-activated K(+) channel inhibitor), whereas glybenclamide [ATP-sensitive K(+) (KATP) channel inhibitor] and inhibitors of nitric oxide (NO) synthase, cyclooxygenase, and cytochrome P-450 epoxygenase had no effect. These data indicate that erectile responses to Na2S are mediated by a tetraethylammonium- and iberiotoxin-sensitive mechanism and that KATP channels, NO, or arachidonic acid metabolites are not involved. Na2S did not alter erectile responses to sodium nitroprusside (NO donor) or cavernosal nerve stimulation, indicating that neither NO nor cGMP metabolism are altered. Thus, Na2S has erectile activity mediated by large-conductance Ca(2+)-activated K(+) channels. It is suggested that strategies that increase H2S formation in penile tissue may be useful in the treatment of erectile dysfunction when NO bioavailability, KATP channel function, or poor responses to PGE1 are present.

Analysis of cardiovascular responses to the H2S donors Na2S and NaHS in the rat.

Hydrogen sulfide (H2S) is an endogenous gaseous molecule formed from L-cysteine in vascular tissue. In the present study, cardiovascular responses to the H2S donors Na2S and NaHS were investigated in the anesthetized rat. The intravenous injections of Na2S and NaHS 0.03-0.5 mg/kg produced dose-related decreases in systemic arterial pressure and heart rate, and at higher doses decreases in cardiac output, pulmonary arterial pressure, and systemic vascular resistance. H2S infusion studies show that decreases in systemic arterial pressure, heart rate, cardiac output, and systemic vascular resistance are well-maintained, and responses to Na2S are reversible. Decreases in heart rate were not blocked by atropine, suggesting that the bradycardia was independent of parasympathetic activation and was mediated by an effect on the sinus node. The decreases in systemic arterial pressure were not attenuated by hexamethonium, glybenclamide, N(w)-nitro-L-arginine methyl ester hydrochloride, sodium meclofenamate, ODQ, miconazole, 5-hydroxydecanoate, or tetraethylammonium, suggesting that ATP-sensitive potassium channels, nitric oxide, arachidonic acid metabolites, cyclic GMP, p450 epoxygenase metabolites, or large conductance calcium-activated potassium channels are not involved in mediating hypotensive responses to the H2S donors in the rat and that responses are not centrally mediated. The present data indicate that decreases in systemic arterial pressure in response to the H2S donors can be mediated by decreases in vascular resistance and cardiac output and that the donors have an effect on the sinus node independent of the parasympathetic system. The present data indicate that the mechanism of the peripherally mediated hypotensive response to the H2S donors is uncertain in the intact rat.

Analysis of erectile responses to bradykinin in the anesthetized rat.

The kallikrein-kinin system is expressed in the corpus cavernosa, and bradykinin (BK) relaxes isolated corpora cavernosal strips. However, erectile responses to BK in the rat have not been investigated in vivo. In the present study, responses to intracorporal (ic) injections of BK were investigated in the anesthetized rat. BK, in doses of 1-100 µg/kg ic, produced dose-related increases in intracavernosal pressure (ICP) and dose-related deceases in mean arterial pressure (MAP). When decreases in MAP were prevented by intravenous injections of angiotensin II (Ang II), increases in ICP, in response to BK, were enhanced. Increases in ICP, ICP/MAP ratio, and area under the curve and decreases in MAP in response to BK were inhibited by the kinin B2 receptor antagonist HOE-140 and enhanced by the angiotensin-converting enzyme (ACE) inhibitor captopril and by Ang-(1-7). Increases in ICP, in response to BK, were not attenuated by the nitric oxide (NO) synthase inhibitor (N(ω)-nitro-L-arginine methyl ester) or the soluble guanylate cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one) but were attenuated by the cyclooxygenase inhibitor, sodium meclofenamate. Decreases in MAP were not attenuated by either inhibitor. These data suggest that erectile responses are mediated by kinin B2 receptors and modulated by decreases in MAP. These data indicate that ACE is important in the inactivation of BK and that erectile and hypotensive responses are independent of NO in the penis or the systemic vascular bed. Erectile responses to cavernosal nerve stimulation are not altered by BK or HOE-140, suggesting that BK and B2 receptors do not modulate nerve-mediated erectile responses under physiologic conditions. These data suggest that erectile responses to BK are mediated, in part, by the release of cyclooxygenase products.

Overview of potential molecular targets for hydrogen sulfide: A new strategy for treating erectile dysfunction.

Hydrogen sulfide (H2S) is a molecule of increasing interest in biology. It is now recognized as the third most important biological gasotransmitter after nitric oxide (NO) and carbon monoxide (CO); it freely diffuses across cellular membranes and affects various physiologic functions. There are functional roles for H2S in sexual medicine related to cavernosal smooth muscle relaxation and the erectile mechanism. H2S may function in both normal endothelial and cavernosal smooth muscle function, as well as in the pathogenesis of erectile dysfunction (ED). This review examines the mechanisms of the role of H2S in the physiology of erection, and how it may be applied in the future to the treatment of men with multiple comorbidities and ED. The efficacy and safety profile of H2S as a therapeutic agent needs to be further defined. As research on this molecule is in the early stages, further investigation is required to determine if the mechanisms of H2S effects in animal models of ED can be translated to the human condition. These initial studies with H2S may lead to new developments in ED treatment.

Emerging drugs for the treatment of erectile dysfunction.

INTRODUCTION: Erectile dysfunction adversely affects the lives of millions of men, and is the most commonly treated sexual disorder today. The erectile process has been extensively investigated, with major advances made in elucidating many of the complex molecular pathways involved. These advances have allowed researchers to design and study drug formulations that target various aspects of this complex process. The initial culmination of this research was the introduction of phosphodiesterase 5-inhibitors. While effective in many patients, they are not satisfactory for all afflicted men. As a result, researchers are developing novel drugs that target different molecular pathways. AREAS COVERED: The paper will review these pathways, and the potential agents that target them. More specifically, first dopaminergic and melanocortin receptor agonists that act centrally will be covered. Then, the paper will examine the "second-generation" phosphodiesterase 5-inhibitors, soluble guanylate cyclases, rho-kinase inhibitors, and maxi-k channel activators that act peripherally. EXPERT OPINION: Most of these novel drugs have yet to reach Phase III studies. However, it is likely that in years to come, patients will be selectively treated with these novel agents as a monotherapy or in combination with others acting in a synergistic manner.

Predicting Limited Survival Following Inguinal Lymph Node Dissection in Penile Cancer: Should We Revisit the Goals of Care?

OBJECTIVE: Patients with advanced penile squamous cell cancer have a poor prognosis and can benefit from early palliative care consultation. We built a model to identify those patients most likely to benefit. METHODS: Patients with penile squamous cell cancer undergoing inguinal lymph node dissection were identified from the National Cancer Database (NCDB) and a multi-institutional international dataset (INT). A multivariable Cox proportional hazards model for overall survival (OS) was developed using the NCDB and applied to the INT dataset. Parameters were used to make receiver operating characteristic (ROC) curves. ROC-related criteria were optimized to identify a predictive probability cut point and dichotomize patients from INT into risk groups for limited OS of <6 and <12 months. RESULTS: NCDB had 860 deaths; 105 (5%) at 6 months and 296 (15%) at 12 months. INT had 257 deaths; 56 (8%) at 6 months and 124 (18%) at 12 months. Limited OS was associated with older age, greater T and N stage, and fewer lymph nodes removed. Optimized ROC criteria using the OS <6 months curve best dichotomized INT patients into high-risk group with median OS of 24 months (95% CI 18-34) and low-risk group with median OS of 174 months (95% CI 120-NE). CONCLUSION: We developed a simple model that could be used as a screening tool for early palliative care referral.

Increased spatial coupling of integrin and collagen IV in the immunoresistant clear cell renal cell carcinoma tumor microenvironment.

Background: Immunotherapy (IO) has improved survival for patients with advanced clear cell renal cell carcinoma (ccRCC), but resistance to therapy develops in most patients. We use cellular-resolution spatial transcriptomics in patients with IO naïve and IO exposed primary ccRCC tumors to better understand IO resistance. Spatial molecular imaging (SMI) was obtained for tumor and adjacent stroma samples. Spatial gene set enrichment analysis (GSEA) and autocorrelation (coupling with high expression) of ligand-receptor transcript pairs were assessed. Multiplex immunofluorescence (mIF) validation was used for significant autocorrelative findings and the cancer genome atlas (TCGA) and the clinical proteomic tumor analysis consortium (CPTAC) databases were queried to assess bulk RNA expression and proteomic correlates. Results: 21 patient samples underwent SMI. Viable tumors following IO harbored more stromal CD8+ T cells and neutrophils than IO naïve tumors. YES1 was significantly upregulated in IO exposed tumor cells. The epithelial-mesenchymal transition pathway was enriched on spatial GSEA and the associated transcript pair COL4A1-ITGAV had significantly higher autocorrelation in the stroma. Fibroblasts, tumor cells, and endothelium had the relative highest expression. More integrin αV+ cells were seen in IO exposed stroma on mIF validation. Compared to other cancers in TCGA, ccRCC tumors have the highest expression of both COL4A1 and ITGAV. In CPTAC, collagen IV protein was more abundant in advanced stages of disease. Conclusions: On spatial transcriptomics, COL4A1 and ITGAV were more autocorrelated in IO-exposed stroma compared to IO-naïve tumors, with high expression amongst fibroblasts, tumor cells, and endothelium. Integrin represents a potential therapeutic target in IO treated ccRCC.

Partial cystectomy for muscle-invasive bladder cancer: a review of the literature.

The radical cystectomy (RC) for muscle-invasive bladder cancer is one of the most morbid and complex urologic procedures performed today. To avoid these complications, the partial cystectomy (PC) has been offered as an alternative in carefully selected patients as a means of achieving equal oncologic efficacy with less morbidity. Selection criteria should include solitary tumors without concomitant carcinoma in situ (CIS) and amenable to resection with 1-2 cm margins in a normally functioning bladder. In addition to the standard work-up, random bladder and prostatic biopsies may be performed. The PC can be performed through an open, laparoscopic, or robot-assisted approach, each with acceptable outcomes. A number of techniques have been developed to identify and resect the tumor completely with negative margins, while preventing tumor spillage within the abdomen. While there are no randomized trials, single institution series have demonstrated acceptable oncologic outcomes in appropriately selected patients. Therefore, offering PC in the appropriate candidate, including those patients who do not accept or are unfit for the associated morbidity of a RC, represents an acceptable alternative.

Mucinous adenocarcinoma of the prostatic urethra following a remote history of primary brachytherapy for prostate cancer.

Secondary malignancies are a known, albeit uncommon, complication of radiation for prostate cancer, either in the form of external beam radiotherapy or seed-implant brachytherapy. Of these secondary malignancies, mucinous adenocarcinoma of the prostatic urothelium is an extremely rare clinical entity that has only once been reported in the literature. We report the case of an 80-year-old gentleman who initially underwent low-dose brachytherapy for low-risk prostate cancer 18 years ago. He subsequently developed recurrent gross hematuria and obstructive voiding symptoms. He underwent cystoscopy and transurethral resection of a large tumor from within the prostate. Final pathology of the tumor revealed a mucinous adenocarcinoma. Further immunostaining revealed this is likely to have originated from the prostatic urothelium. Given his age, comorbidities, and no clear data demonstrating that aggressive extirpative surgery provides a clinical benefit, we elected to undergo surveillance. Clinicians should be aware of mucinous adenocarcinoma of the prostatic urethra as an extremely rare, radiation-induced malignancy. Once a diagnosis is made, extirpative surgery is an option for localized disease, although prognosis remains poor.

Long-term oncologic outcomes of positive surgical margins following robot-assisted partial nephrectomy.

BACKGROUND: Previous reports on positive surgical margin (PSM) after robot-assisted partial nephrectomy (RAPN) have reached inconsistent conclusions as to the impact of a PSM on oncologic outcomes. We sought to determine the effect of PSM on long-term cancer recurrence and survival outcomes. METHODS: We queried our renal oncology database for patients having undergone RAPN and compared recurrence-free survival (RFS) and overall survival (OS) between patients with PSM and negative surgical margin (NSM). Kaplan-Meier analysis was also performed for RFS and OS for PSM versus NSM. RESULTS: Of the 432 patients who underwent RAPN we identified 29 (6.7%) patients with PSM and 403 (93.3%) patients with NSM. Median follow-up for the overall cohort was 45.1 months. Three of the 29 patients with PSM and fourteen of the 403 patients with NSM had disease recurrence (P=0.09). RFS at 24, 48, and 72 months was 95.8%, 90%, and 85.5% for patients with NSM and 96.6%, 86.6%, and 80.4% for patients with PSM, respectively (log-rank P value =0.382). OS at 24, 48, and 72 months was 98%, 93.1%, and 89.7% for patients with NSM and 96.3%, 91.2%, and 85.2% for patients with PSM, respectively (log-rank P value =0.584). CONCLUSIONS: While PSM are relatively uncommon, their presence still serves as a potential risk factor for worse oncologic outcomes. In instances of PSM, immediate secondary intervention is most likely unnecessary and more attentive long-term clinical follow-up, especially in patients with high-risk features, may be more advisable.

Pathologic Complete Response to Neoadjuvant Nivolumab/Ipilimumab in a Patient with Metastatic Renal Cell Carcinoma.

Nivolumab plus ipilimumab represents an effective combination of checkpoint inhibitors that can lead to a durable response with minimal toxicity in patients with metastatic renal cell carcinoma (mRCC). We present a case of a pathologic complete response to neoadjuvant nivolumab plus ipilimumab in a patient with a 13.9 cm left renal mass and significant retroperitoneal and iliac lymphadenopathy, classified as intermediate-risk mRCC. We discuss and review the literature on complete responses after systemic therapy and the ability to predict who has undergone a complete response in the face of residual radiographic evidence of disease.

A Case Report of an Obstructing Ureteral Nephrogenic Adenoma in a Child Managed With Open Ileal Ureter.

Nephrogenic adenoma is a rare, benign lesion that can be encountered anywhere along the urinary tract. It is associated with genitourinary trauma, chronic inflammation, genitourinary surgery, renal transplant, urolithiasis, and radiation. In children, these lesions are almost exclusively found in the bladder. However, we report an unusual case of a 15-year-old boy with no prior urologic history who presented with an obstructing right ureteral nephrogenic adenoma that required an ileal ureter interposition and right ureterectomy.

Syntaxin 6: A novel predictive and prognostic biomarker in papillary renal cell carcinoma.

Syntaxin 6 is a SNARE family protein known to play an important role in intracellular trafficking. Here, we examined the tumorogenic role of syntaxin 6 in renal cell carcinoma (RCC). The Cancer Genome Atlas (TCGA) was queried for clinicopathologic data and syntaxin 6 expression. We found a significant difference in overall survival (OS) between groups, with high syntaxin 6 expression correlating with decreased survival. When stratifying the data based on histological subtype, the papillary RCC subtype exhibited a significant correlation between syntaxin 6 expression and survival. Using ROC curve, we calculated the area under the curve (AUC) to determine the ability of syntaxin 6 to predict 3-year overall survival. The AUC for syntaxin 6 was 0.73, significantly higher compared to 0.52 for T stage. Next, syntaxin 6 expression was evaluated in clear cell (786-O and Caki-1) and papillary (Caki-2 and ACHN) RCC cells. Syntaxin 6 expression was higher in Caki-1 and ACHN RCC cells. Silencing of syntaxin 6 in ACHN cells significantly decreased the cell viability (p < 0.001). Overall, syntaxin 6 could be a prognostic biomarker for patients with papillary RCC and syntaxin 6 inhibitors hold promise as a novel therapy against RCC.

Hypoxia-induced exosome secretion promotes survival of African-American and Caucasian prostate cancer cells.

African American men in the United States have higher mortality due to prostate cancer (PCa) compared to other races. One reason for this disparity is the lack of in-depth understanding of the PCa biology in African Americans. For example, hypoxia in prostate tumor microenvironment is associated with adverse prognosis; still, no hypoxia-related studies have been reported in African Americans. Here, we compared African-American and Caucasian PCa cells for exosome secretion under normoxic (21% O2) and hypoxic (1% O2) conditions. All cell lines showed higher exosome secretion under hypoxia but it was clearly more prominent in African-American PCa cells. Further, under hypoxia, Rab5 (a biomarker for early endosome) was clustered in perinuclear region; and CD63 (a biomarker for exosomes and multivesicular endosomes) showed greater co-localization with actin cytoskeleton especially in African American PCa cells. Importantly, exosome biogenesis inhibitors GW4869 (10-20 µM) or DMA (10-20 µg/ml) significantly decreased cell viability and clonogenicity in PCa cells. Interestingly, we also observed higher level of lactic acid loaded in exosomes secreted under hypoxia. Overall, under chronic hypoxia, PCa cells secrete more exosomes as a survival mechanism to remove metabolic waste.

Author Correction: Hypoxia-induced exosome secretion promotes survival of African-American and Caucasian prostate cancer cells.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Effect of collagenase Clostridium histolyticum on penile vascular and morphological parameters in patients with Peyronie's disease.

BACKGROUND: To examine the changes in penile vascular parameters after the administration of collagenase Clostridium histolyticum (CCH) in patients with Peyronie's disease (PD). METHODS: We retrospectively reviewed the records for all patients treated with CCH for PD between 04/2014 and 05/2017 who underwent penile duplex Doppler ultrasound (PDDU) after pharmacologically induced erection both before and after four cycles of CCH treatment. The primary outcomes measured were changes in peak systolic velocity (PSV), end diastolic velocity (EDV), and resistive index (RI) after CCH treatment. Paired t-tests, chi-squared tests, and correlation coefficients were performed between functional and vascular parameters before and after four rounds of CCH to determine statistical significance (P<0.05). RESULTS: A total of 51 patients were included in the study. After four cycles of CCH therapy, there was no statistically significant change in PSV, EDV, RI, or International Index of Erectile Function score when compared to baseline. Similarly, there was no correlation between vascular parameters and change in curvature. There was a statistically significant change in penile curvature (60˚±16.9˚ to 40.8˚±14.9˚, P<0.001) and erect penile circumference (11.6±1.0 to 11.9±1.0 cm, P<0.05) after treatment. CONCLUSIONS: In spite of a significant change in penile curvature, this change did not correlate with changing penile vascular or morphological parameters. Overall, CCH therapy seems to have a negligible impact on penile vasculature, furthering evidence of its favorable safety profile.