Reducing the Frequency of Follow-up Cystoscopy in Low-grade pTa Non-muscle-invasive Bladder Cancer Using the ADXBLADDER Biomarker.

BACKGROUND: Non-muscle-invasive bladder cancer (NMIBC) is one of the most expensive cancers owing to frequent follow-up cystoscopies for detection of recurrence. OBJECTIVE: To assess if the noninvasive ADXBLADDER urine test could permit a less intensive surveillance schedule for patients with low-grade (LG) pTa tumor without carcinoma in situ (CIS) at the previous diagnosis. DESIGN, SETTING, AND PARTICIPANTS: In a prospective, double-blind, multicenter study, 629 patients underwent follow-up cystoscopy, transurethral resection of bladder tumor/biopsy of suspect lesions, and ADXBLADDER testing. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Diagnostic test accuracy and decision curve analysis were used to evaluate the impact of ADXBLADDER on decision-making on whether to perform follow-up cystoscopy. The primary endpoint was the negative predictive value (NPV) of ADXBLADDER for detection of high-grade and/or CIS (HG/CIS) recurrence and its impact on reducing unnecessary cystoscopies. RESULTS AND LIMITATIONS: ADXBLADDER had sensitivity of 66.7% (95% confidence interval [CI] 34.9-90.1%) and an NPV of 99.15% (95% CI 97.8-99.8%) for detection of HG/CIS recurrence. The probability of HG/CIS recurrence was 5.0% for ADXBLADDER-positive patients and 0.85% for ADXBLADDER-negative patients. For HG/CIS recurrence threshold probabilities between 0.85% and 5.0%, ADXBLADDER yields a net benefit with omission of cystoscopy for ADXBLADDER-negative patients. The corresponding net reduction in unnecessary cystoscopies ranges from 11 to 62 per 100 patients. CONCLUSIONS: Patients with LG pTa tumor at the previous diagnosis, for which the risk of HG/CIS recurrence is low and the ADXBLADDER NPV for ruling out HG/CIS recurrence is 99.15%, are ideally suited for a less intensive, personalized follow-up surveillance strategy using ADXBLADDER, with omission of cystoscopy for ADXBLADDER-negative patients. PATIENT SUMMARY: ADXBLADDER is a urine test that can predict the probability of recurrence of bladder cancer. Patients diagnosed with low-grade cancer confined to the bladder mucosa are ideally suited for less intensive follow-up using this test, which could reduce unnecessary cystoscopy procedures for those with a negative result, potentially improve quality of life, and reduce overall health care costs.

Comparison of the performances of the ADXBLADDER test and urinary cytology in the follow-up of non-muscle-invasive bladder cancer: a blinded prospective multicentric study.

OBJECTIVE: To compare directly the performance of the ADXBLADDER test with that of cytology in the detection of non-muscle-invasive bladder cancer (NMIBC) recurrences. BACKGROUND: ADXBLADDER is a urine test based on the detection of MCM5, a DNA licensing factor expressed in all cells capable of dividing. Expression is usually restricted to the basal stem cell compartment; however, in malignancy, MCM5-expressing cells can be found throughout the epithelium. Detection of MCM5 in urine sediment can be indicative of the presence of a bladder tumour. PATIENTS AND METHODS: A multicentre prospective, blinded study was carried out from August 2017 and July 2019 at 21 European Union centres, 14 of which collected matching cytology data. Urine was collected from patients prior to cystoscopy. Urine cytology and ADXBLADDER were performed and compared to the diagnosis obtained by cystoscopy. The performance of cytology and ADXBLADDER were then compared. RESULTS: The overall performance of ADXBLADDER demonstrated a sensitivity of 51.9%, a specificity of 66.4%, and a negative predictive value (NPV) of 92%. The sensitivity of ADXBLADDER for low- and high-grade recurrences was 44.1% and 58.8%, respectively. By contrast, cytology sensitivity was 16.7%, specificity was 98% and NPV was 90.7%. Cytology sensitivity for both low- and high-grade disease was 17.6%. CONCLUSIONS: ADXBLADDER detection of both low- and high-grade NMIBC recurrence is superior to that of cytology, with ADXBLADDER able to exclude the presence of high-grade recurrence in 97.8% of cases compared to 97.1% with cytology. These results show that ADXBLADDER has promise as a more reliable alternative to urine cytology in the follow-up of NMIBC.

Diagnostic Accuracy of MCM5 for the Detection of Recurrence in Nonmuscle Invasive Bladder Cancer Followup: A Blinded, Prospective Cohort, Multicenter European Study.

PURPOSE: Detection of MCM5 containing cells in urine has been shown to be indicative of the presence of a bladder tumor on primary diagnosis. In this study we evaluate diagnostic performance of ADXBLADDER in patients undergoing cystoscopic surveillance in nonmuscle invasive bladder cancer followup. MATERIALS AND METHODS: A multicenter prospective blinded study was performed at 21 European centers with patients undergoing cystoscopy for nonmuscle invasive bladder cancer surveillance, diagnosed in the preceding 2 years. Urine was collected from all eligible patients and ADXBLADDER-MCM5 testing was performed. Performance characteristics were calculated by comparing MCM5 results to the outcome of cystoscopy plus pathological assessment. RESULTS: Of 1,431 eligible patients enrolled 127 were diagnosed with a bladder cancer recurrence. The overall sensitivity for the ADXBLADDER-MCM5 test in detecting bladder cancer recurrence was 44.9% (95% CI 36.1-54) with a 75.6% sensitivity for nonpTaLG tumors (95% CI 59.7-87.6). Specificity was 71.1% (95% CI 68.5-73.5). The overall negative predictive value was 93% (95% CI 91.2-94.5). However, ADXBLADDER was able to rule out the presence of a nonpTaLG recurrent tumor with a negative predictive value of 99.0% (95% CI 98.2-99.5). No statistically significant differences in the performance of ADXBLADDER were observed as a result of age or sex. CONCLUSIONS: This large blinded prospective study demonstrates that in the followup of patients with nonmuscle invasive bladder cancer ADXBLADDER is able to exclude the presence of the most aggressive tumors with a negative predictive value of 99%. These results indicate that ADXBLADDER could be incorporated in the followup strategy of nonmuscle invasive bladder cancer.

Identification and Characterization of Novel Variations in Platelet G-Protein Coupled Receptor (GPCR) Genes in Patients Historically Diagnosed with Type 1 von Willebrand Disease.

The clinical expression of type 1 von Willebrand disease may be modified by co-inheritance of other mild bleeding diatheses. We previously showed that mutations in the platelet P2Y12 ADP receptor gene (P2RY12) could contribute to the bleeding phenotype in patients with type 1 von Willebrand disease. Here we investigated whether variations in platelet G protein-coupled receptor genes other than P2RY12 also contributed to the bleeding phenotype. Platelet G protein-coupled receptor genes P2RY1, F2R, F2RL3, TBXA2R and PTGIR were sequenced in 146 index cases with type 1 von Willebrand disease and the potential effects of identified single nucleotide variations were assessed using in silico methods and heterologous expression analysis. Seven heterozygous single nucleotide variations were identified in 8 index cases. Two single nucleotide variations were detected in F2R; a novel c.-67G>C transversion which reduced F2R transcriptional activity and a rare c.1063C>T transition predicting a p.L355F substitution which did not interfere with PAR1 expression or signalling. Two synonymous single nucleotide variations were identified in F2RL3 (c.402C>G, p.A134 =; c.1029 G>C p.V343 =), both of which introduced less commonly used codons and were predicted to be deleterious, though neither of them affected PAR4 receptor expression. A third single nucleotide variation in F2RL3 (c.65 C>A; p.T22N) was co-inherited with a synonymous single nucleotide variation in TBXA2R (c.6680 C>T, p.S218 =). Expression and signalling of the p.T22N PAR4 variant was similar to wild-type, while the TBXA2R variation introduced a cryptic splice site that was predicted to cause premature termination of protein translation. The enrichment of single nucleotide variations in G protein-coupled receptor genes among type 1 von Willebrand disease patients supports the view of type 1 von Willebrand disease as a polygenic disorder.

The RNA-binding protein Sam68 regulates expression and transcription function of the androgen receptor splice variant AR-V7.

Castration-resistant (CR) prostate cancer (PCa) partly arises due to persistence of androgen receptor (AR) transcriptional activity in the absence of cognate ligand. An emerging mechanism underlying the CRPCa phenotype and predicting response to therapy is the expression of the constitutively-active AR-V7 splice variant generated by AR cryptic exon 3b inclusion. Here, we explore the role of the RNA-binding protein (RBP) Sam68 (encoded by KHDRBS1), which is over-expressed in clinical PCa, on AR-V7 expression and transcription function. Using a minigene reporter, we show that Sam68 controls expression of exon 3b resulting in an increase in endogenous AR-V7 mRNA and protein expression in RNA-binding-dependent manner. We identify a novel protein-protein interaction between Sam68 and AR-V7 mediated by a common domain shared with full-length AR, and observe these proteins in the cell nucleoplasm. Using a luciferase reporter, we demonstrate that Sam68 co-activates ligand-independent AR-V7 transcriptional activity in an RNA-binding-independent manner, and controls expression of the endogenous AR-V7-specific gene target UBE2C. Our data suggest that Sam68 has separable effects on the regulation of AR-V7 expression and transcriptional activity, through its RNA-binding capacity. Sam68 and other RBPs may control expression of AR-V7 and other splice variants as well as their downstream functions in CRPCa.

Feasibility study of a randomized controlled trial comparing docetaxel chemotherapy and androgen deprivation therapy with sequential prostatic biopsies from patients with advanced non-castration-resistant prostate cancer.

BACKGROUND AND OBJECTIVE: Sequential tissue biopsies taken during clinical trials of novel systemic anticancer therapies for advanced prostate cancer (PCa) may aid pharmacodynamic evaluation and biomarker discovery. We conducted a single institution phase-II open-labeled randomized study to assess the safety, tolerability, and early efficacy of docetaxel chemotherapy plus androgen deprivation therapy (ADT) vs. ADT alone for patients with advanced non-castration-resistant PCa with sequential prostatic biopsies. PATIENTS AND METHODS: We randomized 30 patients with newly diagnosed high-grade locally advanced or metastatic (cT3-4/N0-1/M0-1) PCa to receive ADT with (n = 15) or without (n = 15) docetaxel. Transrectal ultrasound-guided prostatic biopsies were taken at randomization and ~22 weeks after treatment initiation. Primary end point: biochemical response rate. Secondary end points: time to progression and tumor profiling. RESULTS: Both treatments appear to be well tolerated, and there was no difference in mean nadir prostate-specific antigen and time to prostate-specific antigen relapse between treatment arms (P>0.05). No adverse effects of pre- and post-treatment prostatic biopsies were observed. The study was neither designed nor sufficiently powered to demonstrate statistically significant differences in oncological outcomes or safety profiles between the 2 treatment arms. CONCLUSIONS: Despite the lack of statistical power, our study suggests that docetaxel and ADT in combination may be well tolerated with apparently similar short-term efficacy compared with ADT alone for high-grade locally advanced or metastatic non-castration-resistant PCa, Sequential prostatic biopsies may provide tissue for tumor profiling to yield mechanistic or prognostic insights relating to novel systemic anticancer therapies.

The histone demethylase enzyme KDM3A is a key estrogen receptor regulator in breast cancer.

Endocrine therapy has successfully been used to treat estrogen receptor (ER)-positive breast cancer, but this invariably fails with cancers becoming refractory to treatment. Emerging evidence has suggested that fluctuations in ER co-regulatory protein expression may facilitate resistance to therapy and be involved in breast cancer progression. To date, a small number of enzymes that control methylation status of histones have been identified as co-regulators of ER signalling. We have identified the histone H3 lysine 9 mono- and di-methyl demethylase enzyme KDM3A as a positive regulator of ER activity. Here, we demonstrate that depletion of KDM3A by RNAi abrogates the recruitment of the ER to cis-regulatory elements within target gene promoters, thereby inhibiting estrogen-induced gene expression changes. Global gene expression analysis of KDM3A-depleted cells identified gene clusters associated with cell growth. Consistent with this, we show that knockdown of KDM3A reduces ER-positive cell proliferation and demonstrate that KDM3A is required for growth in a model of endocrine therapy-resistant disease. Crucially, we show that KDM3A catalytic activity is required for both ER-target gene expression and cell growth, demonstrating that developing compounds which target demethylase enzymatic activity may be efficacious in treating both ER-positive and endocrine therapy-resistant disease.

Identification of a candidate prognostic gene signature by transcriptome analysis of matched pre- and post-treatment prostatic biopsies from patients with advanced prostate cancer.

BACKGROUND: Although chemotherapy for prostate cancer (PCa) can improve patient survival, some tumours are chemo-resistant. Tumour molecular profiles may help identify the mechanisms of drug action and identify potential prognostic biomarkers. We performed in vivo transcriptome profiling of pre- and post-treatment prostatic biopsies from patients with advanced hormone-naive prostate cancer treated with docetaxel chemotherapy and androgen deprivation therapy (ADT) with an aim to identify the mechanisms of drug action and identify prognostic biomarkers. METHODS: RNA sequencing (RNA-Seq) was performed on biopsies from four patients before and ~22 weeks after docetaxel and ADT initiation. Gene fusion products and differentially-regulated genes between treatment pairs were identified using TopHat and pathway enrichment analyses undertaken. Publically available datasets were interrogated to perform survival analyses on the gene signatures identified using cBioportal. RESULTS: A number of genomic rearrangements were identified including the TMPRSS2/ERG fusion and 3 novel gene fusions involving the ETS family of transcription factors in patients, both pre and post chemotherapy. In total, gene expression analyses showed differential expression of at least 2 fold in 575 genes in post-chemotherapy biopsies. Of these, pathway analyses identified a panel of 7 genes (ADAM7, FAM72B, BUB1B, CCNB1, CCNB2, TTK, CDK1), including a cell cycle-related geneset, that were differentially-regulated following treatment with docetaxel and ADT. Using cBioportal to interrogate the MSKCC-Prostate Oncogenome Project dataset we observed a statistically-significant reduction in disease-free survival of patients with tumours exhibiting alterations in gene expression of the above panel of 7 genes (p = 0.015). CONCLUSIONS: Here we report on the first "real-time" in vivo RNA-Seq-based transcriptome analysis of clinical PCa from pre- and post-treatment TRUSS-guided biopsies of patients treated with docetaxel chemotherapy plus ADT. We identify a chemotherapy-driven PCa transcriptome profile which includes the down-regulation of important positive regulators of cell cycle progression. A 7 gene signature biomarker panel has also been identified in high-risk prostate cancer patients to be of prognostic value. Future prospective study is warranted to evaluate the clinical value of this panel.

The RNA-binding protein hnRNPA2 regulates ß-catenin protein expression and is overexpressed in prostate cancer.

INTRODUCTION: The RNA-binding protein hnRNPA2 (HNRNPA2B1) is upregulated in cancer, where it controls alternative pre-mRNA splicing of cancer-relevant genes. Cytoplasmic hnRNPA2 is reported in aggressive cancers, but is functionally uncharacterized. We explored the role of hnRNPA2 in prostate cancer (PCa). METHODS: hnRNPA2 function/localization/expression in PCa was determined using biochemical approaches (colony forming/proliferation/luciferase reporter assays/flow cytometry/immunohistocytochemistry). Binding of hnRNPA2 within cancer-relevant 3'-UTR mRNAs was identified by bioinformatics. RESULTS: RNAi-mediated knockdown of hnRNPA2 reduced colony forming and proliferation, while hnRNPA2 overexpression increased proliferation of PCa cells. Nuclear hnRNPA2 is overexpressed in high-grade clinical PCa, and is also observed in the cytoplasm in some cases. Ectopic expression of a predominantly cytoplasmic variant hnRNPA2-ΔRGG also increased PCa cell proliferation, suggesting that cytoplasmic hnRNPA2 may also be functionally relevant in PCa. Consistent with its known cytoplasmic roles, hnRNPA2 was associated with 3'-UTR mRNAs of several cancer-relevant mRNAs including ß-catenin (CTNNB1). Both wild-type hnRNPA2 and hnRNPA2-ΔRGG act on CTNNB1 3'-UTR mRNA, increasing endogenous CTNNB1 mRNA expression and ß-catenin protein expression and nuclear localization. CONCLUSION: Nuclear and cytoplasmic hnRNPA2 are present in PCa and appear to be functionally important. Cytoplasmic hnRNPA2 may affect the cancer cell phenotype through 3'-UTR mRNA-mediated regulation of ß-catenin expression and other cancer-relevant genes.

Molecular dynamics analysis of a novel ß3 Pro189Ser mutation in a patient with glanzmann thrombasthenia differentially affecting αIIbß3 and αvß3 expression.

Mutations in ITGA2B and ITGB3 cause Glanzmann thrombasthenia, an inherited bleeding disorder in which platelets fail to aggregate when stimulated. Whereas an absence of expression or qualitative defects of αIIbß3 mainly affect platelets and megakaryocytes, αvß3 has a widespread tissue distribution. Little is known of how amino acid substitutions of ß3 comparatively affect the expression and structure of both integrins. We now report computer modelling including molecular dynamics simulations of extracellular head domains of αIIbß3 and αvß3 to determine the role of a novel ß3 Pro189Ser (P163S in the mature protein) substitution that abrogates αIIbß3 expression in platelets while allowing synthesis of αvß3. Transfection of wild-type and mutated integrins in CHO cells confirmed that only αvß3 surface expression was maintained. Modeling initially confirmed that replacement of αIIb by αv in the dimer results in a significant decrease in surface contacts at the subunit interface. For αIIbß3, the presence of ß3S163 specifically displaces an α-helix starting at position 259 and interacting with ß3R261 while there is a moderate 11% increase in intra-subunit H-bonds and a very weak decrease in the global H-bond network. In contrast, for αvß3, S163 has different effects with ß3R261 coming deeper into the propeller with a 43% increase in intra-subunit H-bonds but with little effect on the global H-bond network. Compared to the WT integrins, the P163S mutation induces a small increase in the inter-subunit fluctuations for αIIbß3 but a more rigid structure for αvß3. Overall, this mutation stabilizes αvß3 despite preventing αIIbß3 expression.

Enrichment of FLI1 and RUNX1 mutations in families with excessive bleeding and platelet dense granule secretion defects.

We analyzed candidate platelet function disorder genes in 13 index cases with a history of excessive bleeding in association with a significant reduction in dense granule secretion and impaired aggregation to a panel of platelet agonists. Five of the index cases also had mild thrombocytopenia. Heterozygous alterations in FLI1 and RUNX1, encoding Friend leukemia integration 1 and RUNT-related transcription factor 1, respectively, which have a fundamental role in megakaryocytopoeisis, were identified in 6 patients, 4 of whom had mild thrombocytopenia. Two FLI1 alterations predicting p.Arg337Trp and p.Tyr343Cys substitutions in the FLI1 DNA-binding domain abolished transcriptional activity of FLI1. A 4-bp deletion in FLI1, and 2 splicing alterations and a nonsense variation in RUNX1, which were predicted to cause haploinsufficiency of either FLI1 or RUNX1, were also identified. Our findings suggest that alterations in FLI1 and RUNX1 may be common in patients with platelet dense granule secretion defects and mild thrombocytopenia.

KDM4B is a master regulator of the estrogen receptor signalling cascade.

The importance of the estrogen receptor (ER) in breast cancer (BCa) development makes it a prominent target for therapy. Current treatments, however, have limited effectiveness, and hence the definition of new therapeutic targets is vital. The ER is a member of the nuclear hormone receptor superfamily of transcription factors that requires co-regulator proteins for complete regulation. Emerging evidence has implicated a small number of histone methyltransferase (HMT) and histone demethylase (HDM) enzymes as regulators of ER signalling, including the histone H3 lysine 9 tri-/di-methyl HDM enzyme KDM4B. Two recent independent reports have demonstrated that KDM4B is required for ER-mediated transcription and depletion of the enzyme attenuates BCa growth in vitro and in vivo. Here we show that KDM4B has an overarching regulatory role in the ER signalling cascade by controlling expression of the ER and FOXA1 genes, two critical components for maintenance of the estrogen-dependent phenotype. KDM4B interacts with the transcription factor GATA-3 in BCa cell lines and directly co-activates GATA-3 activity in reporter-based experiments. Moreover, we reveal that KDM4B recruitment and demethylation of repressive H3K9me3 marks within upstream regulatory regions of the ER gene permits binding of GATA-3 to drive receptor expression. Ultimately, our findings confirm the importance of KDM4B within the ER signalling cascade and as a potential therapeutic target for BCa treatment.

The lysine demethylase, KDM4B, is a key molecule in androgen receptor signalling and turnover.

The androgen receptor (AR) is a key molecule involved in prostate cancer (PC) development and progression. Post-translational modification of the AR by co-regulator proteins can modulate its transcriptional activity. To identify which demethylases might be involved in AR regulation, an siRNA screen was performed to reveal that the demethylase, KDM4B, may be an important co-regulator protein. KDM4B enzymatic activity is required to enhance AR transcriptional activity; however, independently of this activity, KDM4B can enhance AR protein stability via inhibition of AR ubiquitination. Importantly, knockdown of KDM4B in multiple cell lines results in almost complete depletion of AR protein levels. For the first time, we have identified KDM4B to be an androgen-regulated demethylase enzyme, which can influence AR transcriptional activity not only via demethylation activity but also via modulation of ubiquitination. Together, these findings demonstrate the close functional relationship between AR and KDM4B, which work together to amplify the androgen response. Furthermore, KDM4B expression in clinical PC specimens positively correlates with increasing cancer grade (P < 0.001). Consequently, KDM4B is a viable therapeutic target in PC.

Does androgen-ablation therapy (AAT) associated autophagy have a pro-survival effect in LNCaP human prostate cancer cells?

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Androgen-ablation therapy (AAT) and chemotherapy are commonly used to treat incurable prostate cancer. To improve outcome, there is major on-going research to develop more effective treatments with less toxicity. Autophagy has been suggested from previous studies to play a potential role in cell survival and may be associated with resistance to chemotherapy. Autophagy is known to be upregulated by nutrient starvation or AAT in prostate cancer. However, its functional impact is not fully known. The present study describes the potential synergism between the blockade of autophagy and AAT alone or AAT combined with taxane chemotherapy. Hence, future combined treatment options are warranted to further investigate the clinical impact of autophagy suppression as a treatment strategy. OBJECTIVE: To study the cellular effects of the anti-androgen bicalutamide on autophagy and its potential impact on response to androgen-ablation therapy (AAT) alone or combined with docetaxel chemotherapy in human prostate cancer LNCaP cells. MATERIALS AND METHODS: LNCaP cells were treated with bicalutamide ± docetaxel, and cellular effects were assayed: lipidated LC3 (a microtubule-associated protein) for autophagy and its trafficking to fuse with lysosome; flow cytometry using propidium iodide or caspase 3 for cell death; and sulforhodamine B assay for cell growth. RESULTS: Bicalutamide treatment enhanced autophagy in LNCaP cells with increased level of autophagosome coupled with an altered cellular morphology reminiscent of neuroendocrine differentiation. Consistent with the literature on the interaction between androgen receptor activation and taxane chemotherapy, bicalutamide diminished docetaxel mediated cytotoxicity. Significantly, pharmacological inhibition of autophagy with 3-methyladenine significantly enhanced the efficacy cell kill mediated by AAT ± docetaxel. CONCLUSION: Autophagy associated with bicalutamide treatment in LNCaP cells may have a pro-survival effect and strategy to modulate autophagy may have a potential therapeutic value.

Identification of novel androgen-regulated pathways and mRNA isoforms through genome-wide exon-specific profiling of the LNCaP transcriptome.

Androgens drive the onset and progression of prostate cancer (PCa) by modulating androgen receptor (AR) transcriptional activity. Although several microarray-based studies have identified androgen-regulated genes, here we identify in-parallel global androgen-dependent changes in both gene and alternative mRNA isoform expression by exon-level analyses of the LNCaP transcriptome. While genome-wide gene expression changes correlated well with previously-published studies, we additionally uncovered a subset of 226 novel androgen-regulated genes. Gene expression pathway analysis of this subset revealed gene clusters associated with, and including the tyrosine kinase LYN, as well as components of the mTOR (mammalian target of rapamycin) pathway, which is commonly dysregulated in cancer. We also identified 1279 putative androgen-regulated alternative events, of which 325 (∼25%) mapped to known alternative splicing events or alternative first/last exons. We selected 30 androgen-dependent alternative events for RT-PCR validation, including mRNAs derived from genes encoding tumour suppressors and cell cycle regulators. Of seven positively-validating events (∼23%), five events involved transcripts derived from alternative promoters of known AR gene targets. In particular, we found a novel androgen-dependent mRNA isoform derived from an alternative internal promoter within the TSC2 tumour suppressor gene, which is predicted to encode a protein lacking an interaction domain required for mTOR inhibition. We confirmed that expression of this alternative TSC2 mRNA isoform was directly regulated by androgens, and chromatin immunoprecipitation indicated recruitment of AR to the alternative promoter region at early timepoints following androgen stimulation, which correlated with expression of alternative transcripts. Together, our data suggest that alternative mRNA isoform expression might mediate the cellular response to androgens, and may have roles in clinical PCa.

Regulation of the androgen receptor by SET9-mediated methylation.

The androgen receptor (AR) is a member of the nuclear hormone receptor family of transcription factors that plays a critical role in regulating expression of genes involved in prostate development and transformation. Upon hormone binding, the AR associates with numerous co-regulator proteins that regulate the activation status of target genes via flux to the post-translational modification status of histones and the receptor. Here we show that the AR interacts with and is directly methylated by the histone methyltransferase enzyme SET9. Methylation of the AR on lysine 632 is necessary for enhancing transcriptional activity of the receptor by facilitating both inter-domain communication between the N- and C-termini and recruitment to androgen-target genes. We also show that SET9 is pro-proliferative and anti-apoptotic in prostate cancer cells and demonstrates up-regulated nuclear expression in prostate cancer tissue. In all, our date indicate a new mechanism of AR regulation that may be therapeutically exploitable for prostate cancer treatment.

Docetaxel-resistant prostate cancer cells remain sensitive to S-trityl-L-cysteine-mediated Eg5 inhibition.

Castrate-resistant prostate cancer remains a major clinical challenge. Due to the toxicity profile of taxane-based chemotherapy and treatment failure in some patients, novel agents with improved efficacy to side effect profiles are urgently needed. Eg5, a member of the kinesin-5 family, controls the formation of the bipolar spindle during cell division, and suppressed Eg5 function leads to mitotic arrest. S-Trityl-L-cysteine (STLC) is a novel Eg5-specific small-molecule inhibitor. Here, we report the first study to evaluate its use in prostate cancer. In a panel of prostate cancer cells, LNCaP and PC3 cells were the most and least sensitive to STLC treatment, with a 7.2-fold difference in their respective GI(50) values: 250 nmol/L and 1.8 micromol/L. In LNCaP cells, treatment with either STLC or docetaxel resulted in transient G(2)-M arrest and subsequent caspase-mediated cell death. However, STLC- and docetaxel-treated PC3M cells have distinct fates: STLC induced a transient G(2)-M arrest, followed by polyploidy; in contrast, docetaxel-treated PC3M cells progressed to apoptosis after a transient G(2)-M arrest. Docetaxel-resistant LNCaP-derived (LDocR) cells respond to STLC in a similar manner to the parental cells. Although the docetaxel-resistant PC3M-derived (PDocR) cell line and its parental PC3M cells have similar GI(50) to STLC treatment, PDocR cells showed significantly more G(2)-M arrest and less apoptosis. Hence, although docetaxel-resistant prostate cancer cells remain responsive to Eg5 inhibition with STLC, there are key differences at the cell cycle level, which may have implication in future development.