Mechanism of anion exchange and small-molecule inhibition of pendrin.

Pendrin (SLC26A4) is an anion exchanger that mediates bicarbonate (HCO3-) exchange for chloride (Cl-) and is crucial for maintaining pH and salt homeostasis in the kidney, lung, and cochlea. Pendrin also exports iodide (I-) in the thyroid gland. Pendrin mutations in humans lead to Pendred syndrome, causing hearing loss and goiter. Inhibition of pendrin is a validated approach for attenuating airway hyperresponsiveness in asthma and for treating hypertension. However, the mechanism of anion exchange and its inhibition by drugs remains poorly understood. We applied cryo-electron microscopy to determine structures of pendrin from Sus scrofa in the presence of either Cl-, I-, HCO3- or in the apo-state. The structures reveal two anion-binding sites in each protomer, and functional analyses show both sites are involved in anion exchange. The structures also show interactions between the Sulfate Transporter and Anti-Sigma factor antagonist (STAS) and transmembrane domains, and mutational studies suggest a regulatory role. We also determine the structure of pendrin in a complex with niflumic acid (NFA), which uncovers a mechanism of inhibition by competing with anion binding and impeding the structural changes necessary for anion exchange. These results reveal directions for understanding the mechanisms of anion selectivity and exchange and their regulations by the STAS domain. This work also establishes a foundation for analyzing the pathophysiology of mutations associated with Pendred syndrome.

Analysis and comparison of SARS-CoV-2 variant antibodies and neutralizing activity for 6 months after a booster mRNA vaccine in a healthcare worker population.

Introduction: In the context of recurrent surges of SARS-CoV-2 infections, a detailed characterization of antibody persistence over a 6-month period following vaccine booster dose is necessary to crafting effective public health policies on repeat vaccination. Methods: To characterize the SARS-CoV-2 antibody profile of a healthcare worker population over a 6-month period following mRNA vaccination and booster dose. 323 healthcare workers at an academic medical center in Orange County, California who had completed primary vaccination and booster dose against SARS-CoV-2 were recruited for the study. A total of 690 blood specimens over a 6-month period were collected via finger-stick blood and analyzed for the presence of antibodies against 9 SARS-CoV-2 antigens using a coronavirus antigen microarray. Results: The primary outcome of this study was the average SARS-CoV-2 antibody level as measured using a novel coronavirus antigen microarray. Additional outcomes measured include levels of antibodies specific to SARS-CoV-2 variants including Delta, Omicron BA.1, and BA.2. We also measured SARS-CoV-2 neutralization capacity for a subset of the population to confirm correlation with antibody levels. Although antibodies against SARS-CoV-2 wane throughout the 6-month period following a booster dose, antibody levels remain higher than pre-boost levels. However, a booster dose of vaccine based on the original Wuhan strain generates approximately 3-fold lower antibody reactivity against Omicron variants BA.1 and BA.2 as compared to the vaccine strain. Despite waning antibody levels, neutralization activity against the vaccine strain is maintained throughout the 6-month period. Discussion: In the context of recurrent surges of SARS-CoV-2 infections, our data indicate that breakthrough infections are likely driven by novel variants with different antibody specificity and not by time since last dose of vaccination, indicating that development of vaccinations specific to these novel variants is necessary to prevent future surges of SARS-CoV-2 infections.

Analysis and comparison of SARS-CoV-2 variant antibodies and neutralizing activity for 6 months after a booster mRNA vaccine in a healthcare worker population.

In the context of recurrent surges of SARS-CoV-2 infections, a detailed characterization of antibody persistence over a 6-month period following vaccine booster dose is necessary to crafting effective public health policies on repeat vaccination. To characterize the SARS-CoV-2 antibody profile of a healthcare worker population over a 6-month period following mRNA vaccination and booster dose. 323 healthcare workers at an academic medical center in Orange County, California who had completed primary vaccination and booster dose against SARS-CoV-2 were recruited for the study. A total of 690 blood specimens over a 6-month period were collected via finger-stick blood and analyzed for the presence of antibodies against 9 SARS-CoV-2 antigens using a coronavirus antigen microarray. The primary outcome of this study was the average SARS-CoV-2 antibody level as measured using a novel coronavirus antigen microarray. Additional outcomes measured include levels of antibodies specific to SARS-CoV-2 variants including Delta, Omicron BA.1, and BA.2. We also measured SARS-CoV-2 neutralization capacity for a subset of the population to confirm correlation with antibody levels. Although antibodies against SARS-CoV-2 wane throughout the 6-month period following a booster dose, antibody levels remain higher than pre-boost levels. However, a booster dose of vaccine generates approximately 3-fold lower antibody reactivity against Omicron variants BA.1 and BA.2 as compared to the original Wuhan strain. Despite waning antibody levels, neutralization activity against the original Wuhan strain is maintained throughout the 6-month period. In the context of recurrent surges of SARS-CoV-2 infections despite vaccination with booster doses, our data indicate that breakthrough infections are likely driven by novel variants with different antibody specificity and not by time since last dose of vaccination, indicating that development of vaccinations specific to these novel variants is necessary to prevent future surges of SARS-CoV-2 infections.

Structural basis of HIV inhibition by L-nucleosides: Opportunities for drug development and repurposing.

Infection with HIV can cripple the immune system and lead to AIDS. Hepatitis B virus (HBV) is a hepadnavirus that causes human liver diseases. Both pathogens are major public health problems affecting millions of people worldwide. The polymerases from both viruses are the most common drug target for viral inhibition, sharing common architecture at their active sites. The L-nucleoside drugs emtricitabine and lamivudine are widely used HIV reverse transcriptase (RT) and HBV polymerase (Pol) inhibitors. Nevertheless, structural details of their binding to RT(Pol)/nucleic acid remained unknown until recently. Here, we discuss the implications of these structures, alongside related complexes with L-dNTPs, for the development of novel L-nucleos(t)ide drugs, and prospects for repurposing them.

Evaluation of Histone Deacetylase Inhibitors as Radiosensitizers for Proton and Light Ion Radiotherapy.

Significant opportunities remain for pharmacologically enhancing the clinical effectiveness of proton and carbon ion-based radiotherapies to achieve both tumor cell radiosensitization and normal tissue radioprotection. We investigated whether pretreatment with the hydroxamate-based histone deacetylase inhibitors (HDACi) SAHA (vorinostat), M344, and PTACH impacts radiation-induced DNA double-strand break (DSB) induction and repair, cell killing, and transformation (acquisition of anchorage-independent growth in soft agar) in human normal and tumor cell lines following gamma ray and light ion irradiation. Treatment of normal NFF28 primary fibroblasts and U2OS osteosarcoma, A549 lung carcinoma, and U87MG glioma cells with 5-10 µM HDACi concentrations 18 h prior to cesium-137 gamma irradiation resulted in radiosensitization measured by clonogenic survival assays and increased levels of colocalized gamma-H2AX/53BP1 foci induction. We similarly tested these HDACi following irradiation with 200 MeV protons, 290 MeV/n carbon ions, and 350 MeV/n oxygen ions delivered in the Bragg plateau region. Unlike uniform gamma ray radiosensitization, effects of HDACi pretreatment were unexpectedly cell type and ion species-dependent with C-12 and O-16 ion irradiations showing enhanced G0/G1-phase fibroblast survival (radioprotection) and in some cases reduced or absent tumor cell radiosensitization. DSB-associated foci levels were similar for proton-irradiated DMSO control and SAHA-treated fibroblast cultures, while lower levels of induced foci were observed in SAHA-pretreated C-12 ion-irradiated fibroblasts. Fibroblast transformation frequencies measured for all radiation types were generally LET-dependent and lowest following proton irradiation; however, both gamma and proton exposures showed hyperlinear transformation induction at low doses (≤25 cGy). HDACi pretreatments led to overall lower transformation frequencies at low doses for all radiation types except O-16 ions but generally led to higher transformation frequencies at higher doses (>50 cGy). The results of these in vitro studies cast doubt on the clinical efficacy of using HDACi as radiosensitizers for light ion-based hadron radiotherapy given the mixed results on their radiosensitization effectiveness and related possibility of increased second cancer induction.

MRI-guided focal laser ablation of prostate cancer: a prospective single-arm, single-center trial with 3 years of follow-up.

PURPOSE: We aimed to assess post-interventional and 36-month follow-up results of a single-center, single-arm, in-bore phase I trial of focal laser ablation (FLA) guided by multiparametric magnetic resonance imaging (mpMRI). METHODS: FLA procedures were done in-bore MRI using a transperineal approach. Primary endpoints were feasibility and safety expressed as lack of grade 3 complications. Secondary endpoints were changes in international prostate symptom score (IPSS), sexual health inventory for men (SHIM), quality of life (QoL) scores, and serum prostate specific antigen (PSA) levels. Treatment outcomes were assessed by combined mpMRI-ultrasound fusion-guided and extended sextant systematic biopsy after 12, 24, and optionally after 36 months. RESULTS: Fifteen participants were included. Seven patients (46.67%) had Gleason 3+3 and 8 patients (53.33%) had Gleason 3+4 cancer. All patients tolerated the procedure well, and no grade 3/4 complications occurred. All grade 1 and 2 complications were transient and resolved completely. There was no significant change in mean IPSS from baseline (-1, p = 0.460) and QoL (0, p = 0.441) scores following FLA but there was a significant drop in mean SHIM scores (-2, p = 0.010) compared to pretreatment baselines. Mean PSA significantly decreased after FLA (-2.5, p < 0.001). Seven out of 15 patients (46.67%) had residual cancer in, adjacent, or in close proximity to the treatment area (1 × 4+3=7, 1 × 3+4=7, and 5 × 3+3=6). Four out of 15 patients (26.67%) underwent salvage therapy (2 repeat FLA, 2 radical prostatectomy). CONCLUSION: After 3 years of follow-up we conclude focal laser ablation is safe and feasible without significant complications.

Integrative structural biology studies of HIV-1 reverse transcriptase binding to a high-affinity DNA aptamer.

The high-resolution crystal structure of HIV-1 reverse transcriptase (RT) bound to a 38-mer DNA hairpin aptamer with low pM affinity was previously described. The high-affinity binding aptamer contained 2'-O-methyl modifications and a seven base-pair GC-rich tract and the structure of the RT-aptamer complex revealed specific contacts between RT and the template strand of the aptamer. Similar to all crystal structures of RT bound to nucleic acid template-primers, the aptamer bound RT with a bend in the duplex DNA. To understand the structural basis for the ultra-high-affinity aptamer binding, an integrative structural biology approach was used. Hydrogen-deuterium exchange coupled to liquid chromatography-mass spectrometry (HDX-MS) was used to examine the structural dynamics of RT alone and in the presence of the DNA aptamer. RT was selectively labeled with 15N to unambiguously identify peptides from each subunit. HDX of unliganded RT shows a mostly stable core. The p66 fingers and thumb subdomains, and the RNase H domain are relatively dynamic. HDX indicates that both the aptamer and a scrambled version significantly stabilize regions of RT that are dynamic in the absence of DNA. No substantial differences in RT dynamics are observed between aptamer and scrambled aptamer binding, despite a large difference in binding affinity. Small-angle X-ray scattering and circular dichroism spectroscopy were used to investigate the aptamer conformation in solution and revealed a pre-bent DNA that possesses both A- and B-form helical character. Both the 2'-O-methyl modifications and the GC tract appear to contribute to an energetically favorable conformation for binding to RT that contributes to the aptamer's ultra-high affinity for RT. The X-ray structure of RT with an RNA/DNA version of the aptamer at 2.8 Å resolution revealed a potential role of the hairpin positioning in affinity. Together, the data suggest that both the 2'-O-methyl modifications and the GC tract contribute to an energetically favorable conformation for high-affinity binding to RT.

Structural Basis of HIV-1 Inhibition by Nucleotide-Competing Reverse Transcriptase Inhibitor INDOPY-1.

HIV-1 reverse transcriptase (RT) is an essential enzyme, targeting half of approved anti-AIDS drugs. While nucleoside RT inhibitors (NRTIs) are DNA chain terminators, the nucleotide-competing RT inhibitor (NcRTI) INDOPY-1 blocks dNTP binding to RT. Lack of structural information hindered INDOPY-1 improvement. Here we report the HIV-1 RT/DNA/INDOPY-1 crystal structure, revealing a unique mode of inhibitor binding at the polymerase active site without involving catalytic metal ions. The structure may enable new strategies for developing NcRTIs.

Lack of Impact of Robotic Assisted Laparoscopic Radical Prostatectomy on Intraoperative Levels of Prostate Cancer Circulating Tumor Cells.

PURPOSE: While the significance of circulating tumor cells in clinically localized cancer remains controversial, it has been reported that surgical tumor manipulation can increase circulating tumor cells, including during open prostatectomy. To our knowledge it is unknown whether this cell shedding also occurs during minimally invasive prostatectomy, which minimizes tumor palpation and uses earlier vascular control. We tested the impact of robotic assisted laparoscopic radical prostatectomy on intraoperative circulating tumor cell levels. MATERIALS AND METHODS: Circulating tumor cell counts were compared in peripheral blood specimens from 25 patients treated with robotic assisted laparoscopic radical prostatectomy preoperatively vs intraoperatively after prostate excision, in addition to 11 healthy blood donors. Circulating tumor cell detection was performed using EpCAM immunomagnetic enrichment and multiparametric flow cytometry quantification of viable EpCAM positive/prostate specific membrane antigen positive/CD45 negative cells. Intraoperative cell counts and increases were tested in univariable analyses for associations with perioperative variables, histopathology and postoperative progression. RESULTS: Circulating tumor cells were detected in 0% of healthy controls compared to 48% and 52% of prostatectomy cases preoperatively and intraoperatively, respectively (range 1 to 8 cells). There was no difference in the incidence or mean number of circulating tumor cells preoperatively vs intraoperatively. Of the patients 60% had no intraoperative change from preoperative levels. Intraoperative cell increases vs decreases were equally infrequent (each 20%) with no intraoperative increase greater than 1 circulating tumor cell. Intraoperative circulating tumor cell detection was not significantly associated with prostatectomy operative characteristics, histopathology or early postoperative progression at a median 21-month followup. CONCLUSIONS: Robotic assisted laparoscopic radical prostatectomy does not cause significant intraoperative increases in circulating tumor cells in contrast to historical reports of open prostatectomy. These findings may aid urologists in counseling candidates for robotic assisted laparoscopic radical prostatectomy regarding the possibility of intraoperative tumor cell shedding.

Multiparametric magnetic resonance imaging-transrectal ultrasound fusion-assisted biopsy for the diagnosis of local recurrence after radical prostatectomy.

OBJECTIVE: Approximately 15% of patients who undergo radical prostatectomy (RP) for prostate cancer develop local recurrence, which is heralded by a rise in serum prostate-specific antigen (PSA) levels. Early detection and treatment of recurrence improves the outcome of salvage treatment. We investigated the ability of multiparametric magnetic resonance imaging (mpMRI)-transrectal ultrasound (TRUS) fusion-guided biopsy (FGB) combined with "cognitive biopsy" to confirm local recurrence of prostate cancer after RP. MATERIALS AND METHODS: In this retrospective study conducted between January 2010 and December 2014, patients with rising PSA levels after RP who had no known evidence of distant metastases underwent mpMRI including T2-weighted (T2W) imaging, diffusion-weighted imaging, dynamic contrast-enhanced (DCE) MRI at 3 Tesla, and subsequent MRI-ultrasound fusion biopsy with cognitive assistance. The detection rate of locally recurrent disease was determined. RESULTS: A total of 10 patients (mean age = 67y, mean PSA level = 3.44ng/ml) met the inclusion criteria. Of the 10 patients, all had positive findings suspicious for local recurrence on mpMRI per entrance criterion. The most important features on mpMRI were early enhancement on DCE MR images and hypointensity on T2W images. The average lesion diameter on mpMRI was 1.12cm (range: 0.40-2.20cm). All suspicious lesions (16/16, 100%) were positive on T2W MR images, 14 (89%) showed positive features on apparent diffusion coefficient maps of diffusion-weighted images, and 16 (100%) were positive on DCE MR images. MRI-TRUS FGBs were positive in 10/16 lesions (62.5%) and 8/10 (80%) patients. CONCLUSION: MRI-TRUS FGB with cognitive assistance is able to detect and diagnose locally recurrent lesions after RP, even at low PSA levels. This may facilitate early detection of recurrent disease and improve salvage treatment outcomes.

Diagnostic value of biparametric magnetic resonance imaging (MRI) as an adjunct to prostate-specific antigen (PSA)-based detection of prostate cancer in men without prior biopsies.

OBJECTIVES: To determine the diagnostic yield of analysing biparametric (T2- and diffusion-weighted) magnetic resonance imaging (B-MRI) for prostate cancer detection compared with standard digital rectal examination (DRE) and prostate-specific antigen (PSA)-based screening. PATIENTS AND METHODS: Review of patients who were enrolled in a trial to undergo multiparametric-prostate (MP)-MRI and MR/ultrasound fusion-guided prostate biopsy at our institution identified 143 men who underwent MP-MRI in addition to standard DRE and PSA-based prostate cancer screening before any prostate biopsy. Patient demographics, DRE staging, PSA level, PSA density (PSAD), and B-MRI findings were assessed for association with prostate cancer detection on biopsy. RESULTS: Men with detected prostate cancer tended to be older, with a higher PSA level, higher PSAD, and more screen-positive lesions (SPL) on B-MRI. B-MRI performed well for the detection of prostate cancer with an area under the curve (AUC) of 0.80 (compared with 0.66 and 0.74 for PSA level and PSAD, respectively). We derived combined PSA and MRI-based formulas for detection of prostate cancer with optimised thresholds. (i) for PSA and B-MRI: PSA level + 6 x (the number of SPL) > 14 and (ii) for PSAD and B-MRI: 14 × (PSAD) + (the number of SPL) >4.25. AUC for equations 1 and 2 were 0.83 and 0.87 and overall accuracy of prostate cancer detection was 79% in both models. CONCLUSIONS: The number of lesions positive on B-MRI outperforms PSA alone in detection of prostate cancer. Furthermore, this imaging criteria coupled as an adjunct with PSA level and PSAD, provides even more accuracy in detecting clinically significant prostate cancer.

Image-guided focal therapy for prostate cancer.

The adoption of routine prostate specific antigen screening has led to the discovery of many small and low-grade prostate cancers which have a low probability of causing mortality. These cancers, however, are often treated with radical therapies resulting in long-term side effects. There has been increasing interest in minimally invasive focal therapies to treat these tumors. While imaging modalities have improved rapidly over the past decade, similar advances in image-guided therapy are now starting to emerge--potentially achieving equivalent oncologic efficacy while avoiding the side effects of conventional radical surgery. The purpose of this article is to review the existing literature regarding the basis of various focal therapy techniques such as cryotherapy, microwave, laser, and high intensity focused ultrasound, and to discuss the results of recent clinical trials that demonstrate early outcomes in patients with prostate cancer.

Natural history of small index lesions suspicious for prostate cancer on multiparametric MRI: recommendations for interval imaging follow-up.

PURPOSE: We aimed to determine the natural history of small index lesions identified on multiparametric-magnetic resonance imaging (MP-MRI) of the prostate by evaluating lesion-specific pathology and growth on serial MP-MRI. MATERIALS AND METHODS: We performed a retrospective review of 153 patients who underwent a minimum of two MP-MRI sessions, on an institutional review board-approved protocol. Index lesion is defined as the lesion(s) with the highest cancer suspicion score based on initial MP-MRI of a patient, irrespective of size. Two study cohorts were identified: (1) patients with no index lesion or index lesion(s) ≤7 mm and (2) a subset with no index lesion or index lesion(s) ≤5 mm. Pathological analysis of the index lesions was performed following magnetic resonance/ultrasound fusion-guided biopsy. Growth rate of the lesions was calculated based on MP-MRI follow-up. RESULTS: Patients with small index lesions measuring ≤7 mm (n=42) or a subset with lesions ≤5 mm (n=20) demonstrated either benign findings (86.2% and 87.5%, respectively) or low grade Gleason 6 prostate cancer (13.8% and 12.5%, respectively) on lesion-specific targeted biopsies. These lesions demonstrated no significant change in size (P = 0.93 and P = 0.36) over a mean imaging period of 2.31±1.56 years and 2.40±1.77 years for ≤7 mm and ≤5 mm index lesion thresholds, respectively. These findings held true on subset analyses of patients who had a minimum of two-year interval follow-up with MP-MRI. CONCLUSION: Small index lesions of the prostate are pathologically benign lesions or occasionally low-grade cancers. Slow growth rate of these small index lesions on serial MP-MRI suggests a surveillance interval of at least two years without significant change.

Multiparametric magnetic resonance imaging (MRI) and subsequent MRI/ultrasonography fusion-guided biopsy increase the detection of anteriorly located prostate cancers.

OBJECTIVE: To describe the detection rate of anteriorly located prostate cancer (PCa) with the addition of magnetic resonance imaging (MRI)/ultrasonography (US) fusion-guided biopsy (FGB) to the standard transrectal ultrasonography (TRUS)-guided biopsy. PATIENTS AND METHODS: All patients, regardless of their biopsy history, who were referred for clinical suspicion of PCa (i.e elevated prostate-specific antigen (PSA) level and abnormal digital rectal examination) underwent 3T multiparametric-MRI (mpMRI) screening; and those with suspicious lesions in the anterior region of the prostate were identified. Patients then received a FGB of all suspicious lesions in addition to a systematic 12-core extended sextant TRUS-guided biopsy. We conducted a lesion-based analysis comparing cancer detection rates of anterior targets using FGB vs systematic cores taken from the same anatomic sextant within the prostate. Lengths of cancer in the most involved core were also compared between the two biopsy techniques used. Patients with only anterior targets were analysed separately. RESULTS: Of 499 patients undergoing FGB, 162 had a total of 241 anterior lesions. The mean age, PSA level and prostate volume in this group were 62 years, 12.7 ng/dL, and 57 mL, respectively. In total, PCa was diagnosed in 121 anterior lesions (50.2%) identified on mpMRI. Sixty-two (25.7%) of these anterior lesions were documented as positive for cancer on systematic 12-core TRUS-guided biopsy cores, while 97 (40.2%) were positive on the targeted FGB cores (P = 0.001). In lesions that were positive on both FGB and TRUS biopsy, the most involved core was 112% longer on FGB (3.7 vs 1.6 mm, P ≤ 0.01). Forty-two patients had only anterior lesions on mpMRI; of these, 24 (57.1%) were found to have cancer on the FGB + TRUS biopsy platform. Six patients were positive on FGB only and 13 were positive on both biopsy techniques; however, 7/13 patients were upgraded to a higher Gleason score after FGB. All five patients positive on TRUS biopsy only were candidates for active surveillance. CONCLUSION: The results showed that FGB detects significantly more anteriorly located PCa than does TRUS-guided biopsy alone and it may serve as an effective tool for the subset of patients with such tumours.

Imaging and pathology findings after an initial negative MRI-US fusion-guided and 12-core extended sextant prostate biopsy session.

PURPOSE: A magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided prostate biopsy increases detection rates compared to an extended sextant biopsy. The imaging characteristics and pathology outcomes of subsequent biopsies in patients with initially negative MRI-US fusion biopsies are described in this study. MATERIALS AND METHODS: We reviewed 855 biopsy sessions of 751 patients (June 2007 to March 2013). The fusion biopsy consisted of two cores per lesion identified on multiparametric MRI (mpMRI) and a 12-core extended sextant transrectal US (TRUS) biopsy. Inclusion criteria were at least two fusion biopsy sessions, with a negative first biopsy and mpMRI before each. RESULTS: The detection rate on the initial fusion biopsy was 55.3%; 336 patients had negative findings. Forty-one patients had follow-up fusion biopsies, but only 34 of these were preceded by a repeat mpMRI. The median interval between biopsies was 15 months. Fourteen patients (41%) were positive for cancer on the repeat MRI-US fusion biopsy. Age, prostate-specific antigen (PSA), prostate volume, PSA density, digital rectal exam findings, lesion diameter, and changes on imaging were comparable between patients with negative and positive rebiopsies. Of the patients with positive rebiopsies, 79% had a positive TRUS biopsy before referral (P = 0.004). Ten patients had Gleason 3+3 disease, three had 3+4 disease, and one had 4+4 disease. CONCLUSION: In patients with a negative MRI-US fusion prostate biopsy and indications for repeat biopsy, the detection rate of the follow-up sessions was lower than the initial detection rate. Of the prostate cancers subsequently found, 93% were low grade (≤ 3+4). In this low risk group of patients, increasing the follow-up time interval should be considered in the appropriate clinical setting.

Asymmetric Hsp90 N domain SUMOylation recruits Aha1 and ATP-competitive inhibitors.

The stability and activity of numerous signaling proteins in both normal and cancer cells depends on the dimeric molecular chaperone heat shock protein 90 (Hsp90). Hsp90's function is coupled to ATP binding and hydrolysis and requires a series of conformational changes that are regulated by cochaperones and numerous posttranslational modifications (PTMs). SUMOylation is one of the least-understood Hsp90 PTMs. Here, we show that asymmetric SUMOylation of a conserved lysine residue in the N domain of both yeast (K178) and human (K191) Hsp90 facilitates both recruitment of the adenosine triphosphatase (ATPase)-activating cochaperone Aha1 and, unexpectedly, the binding of Hsp90 inhibitors, suggesting that these drugs associate preferentially with Hsp90 proteins that are actively engaged in the chaperone cycle. Importantly, cellular transformation is accompanied by elevated steady-state N domain SUMOylation, and increased Hsp90 SUMOylation sensitizes yeast and mammalian cells to Hsp90 inhibitors, providing a mechanism to explain the sensitivity of cancer cells to these drugs.

Clinical significance of ureteric 'skip lesions' at the time of radical cystectomy: the M.D. Anderson experience and literature review.

OBJECTIVE: To assess the incidence and clinical significance of 'skip lesions' that are present in proximal but not in distal ureteric sections, which are occasionally found during the pathological examination of ureteric margins during radical cystectomy (RC). PATIENTS AND METHODS: We identified 660 patients who underwent a RC and had at least two permanent margins for a given ureter. In all, 1173 ureters were analysed and classified as follows: 'normal' (no tumour, reactive atypia, mild or moderate dysplasia) or 'abnormal' (severe dysplasia, carcinoma in situ (CIS), or tumour). Transitions from 'normal' distal pathology to 'abnormal' on proximal section(s) determined frequency of skip lesions. Fisher's exact test and the log-rank test were used to study correlations. RESULTS: Ureteric skip lesions were found in 4.8% patients (2.9% ureters). Pathology of skip lesions was CIS in 55.9%, transitional cell carcinoma in 23.5% and severe dysplasia in 20.6%. Skip lesions were associated with lymphovascular invasion (34.4% vs 13.7%, P = 0.004) and advanced pT stage (P = 0.007). On multivariate analysis, skip lesions correlated with lower median overall survival (OS) (inestimable vs 8.2 years, P = 0.014) in patients with pT0 or pTa disease and a trend towards lower OS (2.7 vs 8.8 years, P = 0.066) in pTis disease. Concordance between frozen distal margin and permanent proximal margin varied; sensitivity was 80% in those without and 20% in those with skip lesions. CONCLUSIONS: The presence of a ureteric skip lesion may be associated with lower survival in patients with pT0, pTa or pTis urothelial carcinoma. Thus, while uncommon, ureteric skip lesions should be reported in pathological findings.

MRI characterization of the dynamic effects of 5α-reductase inhibitors on prostate zonal volumes.

INTRODUCTION: Prior studies of volumetric effects of 5α-reductase inhibitors (5ARIs) on the prostate have used transrectal ultrasound which provides poor differentiation of prostatic zones. We utilized high-resolution prostate MRI to evaluate the true dynamic effects of 5ARI in men who underwent multiple MRIs. MATERIALS AND METHODS: A retrospective study of patients who underwent serial 3.0 Tesla prostate MRI from 2007 to 2012 and were treated with 5ARI were studied. Nineteen patients who had a baseline MRI prior to 5ARI initiation and subsequent MRI follow up were selected. A randomly selected group of 40 patients who had not received any form of therapy was selected as the control cohort. Total prostate volume (TPV), transition zone volume (TZV), and peripheral zone volume (PZV) were calculated using 3D reconstructions and prostate segmentation from T2-weighted MRI. Changes in volumes were correlated with the duration of treatment using linear regression analysis. RESULTS: Following over 2 years of treatment, 5ARI decreased TPV significantly (16.7%, p < 0.0001). There were similar decreases in TZV (7.5%, p < 0.001) and PZV (27.4%, p = 0.0002) from baseline. In the control group, TPV and TZV increased (p < 0.0001) while PZV remained stable. When adjusted for the natural growth of prostate zonal volume dynamics seen in the control cohort, approximately 60% of the reduction of the TPV from 5ARI resulted from changes in the TZV and 40% of the reduction from changes in the PZV. CONCLUSIONS: 3.0 Tesla MRI characterizations of the dynamic effects of 5ARI on prostate zonal volumes demonstrate significant decreases in TPV, TZV, and PZV. 5ARI blocks the natural growth of TZV as men age and decreases both TZV and PZV below their baselines. As imaging technology improves, prostate MRI allows for more accurate assessment of drug effects on dynamic prostate volumes.

Accuracy of multiparametric magnetic resonance imaging in confirming eligibility for active surveillance for men with prostate cancer.

BACKGROUND: Active surveillance (AS) is an attempt to avoid overtreatment of clinically insignificant prostate cancer (PCa); however, patient selection remains controversial. Multiparametric prostate magnetic resonance imaging (MP-MRI) may help better select AS candidates. METHODS: We reviewed a cohort of men who underwent MP-MRI with MRI/Ultrasound fusion-guided prostate biopsy and selected potential AS patients at entry using Johns Hopkins criteria. MP-MRI findings were assessed, including number of lesions, dominant lesion diameter, total lesion volume, prostate volume, and lesion density (calculated as total lesion volume/prostate volume). Lesions were assigned a suspicion score for cancer by MRI. AS criteria were reapplied based on the confirmatory biopsy, and accuracy of MP-MRI in predicting AS candidacy was assessed. Logistic regression modeling and chi-square statistics were used to assess associations between MP-MRI interpretation and biopsy results. RESULTS: Eighty-five patients qualified for AS with a mean age of 60.2 years and mean prostate-specific antigen level of 4.8 ng/mL. Of these, 25 patients (29%) were reclassified as not meeting AS criteria based on confirmatory biopsy. Number of lesions, lesion density, and highest MRI lesion suspicion were significantly associated with confirmatory biopsy AS reclassification. These MRI-based factors were combined to create a nomogram that generates a probability for confirmed AS candidacy. CONCLUSION: As clinicians counsel patients with PCa, MP-MRI may contribute to the decision-making process when considering AS. Three MRI-based factors (number of lesions, lesion suspicion, and lesion density) were associated with confirmatory biopsy outcome and reclassification. A nomogram using these factors has promising predictive accuracy for which future validation is necessary. Cancer 2013;119:3359-66. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Magnetic resonance imaging/ultrasound-fusion biopsy significantly upgrades prostate cancer versus systematic 12-core transrectal ultrasound biopsy.

BACKGROUND: Gleason scores from standard, 12-core prostate biopsies are upgraded historically in 25-33% of patients. Multiparametric prostate magnetic resonance imaging (MP-MRI) with ultrasound (US)-targeted fusion biopsy may better sample the true gland pathology. OBJECTIVE: The rate of Gleason score upgrading from an MRI/US-fusion-guided prostate-biopsy platform is compared with a standard 12-core biopsy regimen alone. DESIGN, SETTING, AND PARTICIPANTS: There were 582 subjects enrolled from August 2007 through August 2012 in a prospective trial comparing systematic, extended 12-core transrectal ultrasound biopsies to targeted MRI/US-fusion-guided prostate biopsies performed during the same biopsy session. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: The highest Gleason score from each biopsy method was compared. INTERVENTIONS: An MRI/US-fusion-guided platform with electromagnetic tracking was used for the performance of the fusion-guided biopsies. RESULTS AND LIMITATIONS: A diagnosis of prostate cancer (PCa) was made in 315 (54%) of the patients. Addition of targeted biopsy led to Gleason upgrading in 81 (32%) cases. Targeted biopsy detected 67% more Gleason ≥4+3 tumors than 12-core biopsy alone and missed 36% of Gleason ≤3+4 tumors, thus mitigating the detection of lower-grade disease. Conversely, 12-core biopsy led to upgrading in 67 (26%) cases over targeted biopsy alone but only detected 8% more Gleason ≥4+3 tumors. On multivariate analysis, MP-MRI suspicion was associated with Gleason score upgrading in the targeted lesions (p<0.001). The main limitation of this study was that definitive pathology from radical prostatectomy was not available. CONCLUSIONS: MRI/US-fusion-guided biopsy upgrades and detects PCa of higher Gleason score in 32% of patients compared with traditional 12-core biopsy alone. Targeted biopsy technique preferentially detects higher-grade PCa while missing lower-grade tumors.