ST6GAL1-mediated aberrant sialylation promotes prostate cancer progression.

Aberrant glycosylation is a universal feature of cancer cells, and cancer-associated glycans have been detected in virtually every cancer type. A common change in tumour cell glycosylation is an increase in α2,6 sialylation of N-glycans, a modification driven by the sialyltransferase ST6GAL1. ST6GAL1 is overexpressed in numerous cancer types, and sialylated glycans are fundamental for tumour growth, metastasis, immune evasion, and drug resistance, but the role of ST6GAL1 in prostate cancer is poorly understood. Here, we analyse matched cancer and normal tissue samples from 200 patients and verify that ST6GAL1 is upregulated in prostate cancer tissue. Using MALDI imaging mass spectrometry (MALDI-IMS), we identify larger branched α2,6 sialylated N-glycans that show specificity to prostate tumour tissue. We also monitored ST6GAL1 in plasma samples from >400 patients and reveal ST6GAL1 levels are significantly increased in the blood of men with prostate cancer. Using both in vitro and in vivo studies, we demonstrate that ST6GAL1 promotes prostate tumour growth and invasion. Our findings show ST6GAL1 introduces α2,6 sialylated N-glycans on prostate cancer cells and raise the possibility that prostate cancer cells can secrete active ST6GAL1 enzyme capable of remodelling glycans on the surface of other cells. Furthermore, we find α2,6 sialylated N-glycans expressed by prostate cancer cells can be targeted using the sialyltransferase inhibitor P-3FAX -Neu5Ac. Our study identifies an important role for ST6GAL1 and α2,6 sialylated N-glycans in prostate cancer progression and highlights the opportunity to inhibit abnormal sialylation for the development of new prostate cancer therapeutics. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Upregulation of GALNT7 in prostate cancer modifies O-glycosylation and promotes tumour growth.

Prostate cancer is the most common cancer in men and it is estimated that over 350,000 men worldwide die of prostate cancer every year. There remains an unmet clinical need to improve how clinically significant prostate cancer is diagnosed and develop new treatments for advanced disease. Aberrant glycosylation is a hallmark of cancer implicated in tumour growth, metastasis, and immune evasion. One of the key drivers of aberrant glycosylation is the dysregulated expression of glycosylation enzymes within the cancer cell. Here, we demonstrate using multiple independent clinical cohorts that the glycosyltransferase enzyme GALNT7 is upregulated in prostate cancer tissue. We show GALNT7 can identify men with prostate cancer, using urine and blood samples, with improved diagnostic accuracy than serum PSA alone. We also show that GALNT7 levels remain high in progression to castrate-resistant disease, and using in vitro and in vivo models, reveal that GALNT7 promotes prostate tumour growth. Mechanistically, GALNT7 can modify O-glycosylation in prostate cancer cells and correlates with cell cycle and immune signalling pathways. Our study provides a new biomarker to aid the diagnosis of clinically significant disease and cements GALNT7-mediated O-glycosylation as an important driver of prostate cancer progression.

Chemoradiotherapy in Muscle-invasive Bladder Cancer: 10-yr Follow-up of the Phase 3 Randomised Controlled BC2001 Trial.

BACKGROUND: BC2001, the largest randomised trial of bladder-sparing treatment for muscle-invasive bladder cancer (MIBC), demonstrated improvement in locoregional control by adding fluorouracil and mitomycin C to radiotherapy (James ND, Hussain SA, Hall E, et al. Radiotherapy with or without chemotherapy in muscle-invasive bladder cancer. N Engl J Med 2012;366:1477-88). There are limited data on long-term recurrence risk. OBJECTIVE: To determine whether benefit of adding chemotherapy to radiotherapy for MIBC is maintained in the long term. DESIGN, SETTING, AND PARTICIPANTS: A phase 3 randomised controlled 2 × 2 factorial trial was conducted. Between 2001 and 2008, 458 patients with T2-T4a N0M0 MIBC were enrolled; 360 were randomised to radiotherapy (178) or chemoradiotherapy (182), and 218 were randomised to standard whole-bladder radiotherapy (108) or reduced high-dose-volume radiotherapy (111). The median follow-up time was 9.9 yr. The trial is registered (ISRCTN68324339). INTERVENTION: Radiotherapy: 55 Gy in 20 fractions over 4 wk or 64 Gy in 32 fractions over 6.5 wk; concurrent chemotherapy: 5-fluorouracil and mitomycin C. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Locoregional control (primary endpoint), invasive locoregional control, toxicity, rate of salvage cystectomy, disease-free survival (DFS), metastasis-free survival (MFS), bladder cancer-specific survival (BCSS), and overall survival. Cox regression was used. The analysis of efficacy outcomes was by intention to treat. RESULTS AND LIMITATIONS: Chemoradiotherapy improved locoregional control (hazard ratio [HR] 0.61 [95% confidence interval {CI} 0.43-0.86], p = 0.004) and invasive locoregional control (HR 0.55 [95% CI 0.36-0.84], p = 0.006). This benefit translated, albeit nonsignificantly, for disease-related outcomes: DFS (HR 0.78 [95% CI 0.60-1.02], p = 0.069), MFS (HR 0.78, [95% CI 0.58-1.05], p = 0.089), overall survival (HR = 0.88 [95% CI 0.69-1.13], p = 0.3), and BCSS (HR 0.79 [95% CI 0.59-1.06], p = 0.11). The 5-yr cystectomy rate was 14% (95% CI 9-21%) with chemoradiotherapy versus 22% (95% CI 16-31%) with radiotherapy alone (HR 0.54, [95% CI 0.31-0.95], p = 0.034). No differences were seen between standard and reduced high-dose-volume radiotherapy. CONCLUSIONS: Long-term findings confirm the benefit of adding concomitant 5-fluorouracil and mitomycin C to radiotherapy for MIBC. PATIENT SUMMARY: We looked at long-term outcomes of a phase 3 clinical trial testing radiotherapy with or without chemotherapy for patients with invasive bladder cancer. We concluded that the benefit of adding chemotherapy to radiotherapy was maintained over 10 yr.

Percutaneous microwave ablation of renal masses in a UK cohort.

OBJECTIVES: To report a tertiary referral centre's experience of microwave ablation (MWA) for suspected renal cell carcinoma (RCC), describing complications and oncological outcomes. PATIENTS AND METHODS: Consecutive MWA procedures (n = 113) for renal masses (October 2016 to September 2019) were maintained on a prospective database. Data describing patient, disease, procedure, complications, and oncological outcomes were analysed. RESULTS: The median (range) age was 68 (33-85) years, 73% were male, and the median Charlson Comorbidity Index was 0. The median (interquartile range [IQR]) tumour diameter was 25 (20-32) mm. In all, 95% had renal mass biopsy, with histologically confirmed cancer in 75%. The median (IQR) R.E.N.A.L. (Radius, Exophytic/Endophytic, Nearness, Anterior/Posterior, Location) nephrometry score was 7 (6-8). The median ablation time was 6 min and length of stay was 1 day for 95% of the patients. Clavien-Dindo complication Grades I, II, IIIb and IV occurred in 18%, 1.8%, 0.9% and 0.9%, respectively. The median follow-up was 12 months and the median (IQR) renal function change was -4 (-18 to 0)%. One patient (0.9%) had local recurrence, treated with re-ablation; two developed metastatic progression; and two (1.8%) had indeterminate findings on follow-up (one lung nodule and one possible local recurrence), managed with ongoing protocolised computed tomography surveillance. Post-procedure complications were associated with total ablation time (odds ratio [OR] 1.152/min, 95% confidence interval [CI] 1.040-1.277) and total ablation energy (OR 1.017/kJ, 95% CI 1.001-1.033). CONCLUSIONS: We describe the largest UK series of MWA treatment for T1a/small T1b renal masses to date. MWA was well tolerated, with 95% discharged the following day and low complication/re-admission rates. Current follow-up demonstrates favourable disease control. MWA appears to be safe and effective and should be considered in future prospective comparisons of treatments for T1a/small T1b renal masses.

Outcomes in Patients with Muscle-invasive Bladder Cancer Treated with Neoadjuvant Chemotherapy Followed by (Chemo)radiotherapy in the BC2001 Trial.

BACKGROUND: BC2001 demonstrated improved local control with the addition of chemotherapy to radiotherapy in 360 patients with muscle-invasive bladder cancer. OBJECTIVE: To establish whether such benefit remained in BC2001 patients who received prior neoadjuvant chemotherapy. DESIGN, SETTING, AND PARTICIPANTS: A total of 117 patients (33%) received neoadjuvant chemotherapy and were randomised to radiotherapy with (48%) or without (52%) concomitant chemotherapy. Patients were recruited between August 2001 and April 2008 from 28 UK centres. INTERVENTION: Platinum-based neoadjuvant chemotherapy, followed by radiotherapy with (cRT) or without (RT) synchronous 5-fluorouracil and mitomycin-C. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Toxicity, locoregional control (LRC), overall survival (OS), and quality of life (QoL) were measured. RESULTS AND LIMITATIONS: Of the patients, 74% received gemcitabine plus cisplatin or carboplatin. Compliance rates with full-dose radiotherapy were cRT 93% and RT 92%. An excess of grade ≥3 toxicities while on (chemo)radiation occurred for cRT 33% versus RT 22%, although nonstatistically significant (p = 0.16). With 110 mo median follow-up for survival (interquartile range 96-123), cRT showed improved LRC though not statistically significant (adjusted hazard ratio [aHR] = 0.64, 95% confidence interval [CI] 0.33-1.23, p = 0.18). No differences in OS (aHR = 0.95, 95% CI 0.57-1.57, p = 0.8) were observed. No significant detriment in QoL was observed between cRT and RT in this subgroup of patients. CONCLUSIONS: Neoadjuvant chemotherapy does not compromise the delivery of radical curative treatment. Although underpowered due to a small sample size, the benefit of chemoradiotherapy to improve local control in this group of patients receiving neoadjuvant chemotherapy is consistent with that observed in the main trial. Although a nonsignificant excess of toxicity was observed, there was no evidence of impaired QoL. PATIENT SUMMARY: Chemotherapy before radical chemo(radiotherapy) is feasible and well tolerated.

Patient-reported Quality of Life Outcomes in Patients Treated for Muscle-invasive Bladder Cancer with Radiotherapy ± Chemotherapy in the BC2001 Phase III Randomised Controlled Trial.

BACKGROUND: BC2001, the largest randomised trial of bladder-sparing treatment for muscle-invasive bladder cancer, demonstrated improvement of local control and bladder cancer-specific survival from the addition of concomitant 5-fluorouracil and mitomycin C to radiotherapy. OBJECTIVE: To determine the impact of treatment on the health-related quality of life (HRQoL) of BC2001 participants. DESIGN, SETTING, AND PARTICIPANTS: 458 UK patients with T2-T4a N0 M0 transitional cell carcinoma of the bladder. INTERVENTION: Patients were randomised to the chemotherapy comparison (radiotherapy, 178, or chemoradiotherapy, 182); and/or to the radiotherapy comparison (standard, 108, or reduced high-dose volume radiotherapy, 111). OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Patients completed Functional Assessment of Cancer Therapy-Bladder (FACT-BL) questionnaires at baseline, end of treatment (EoT), and 6, 12, 24, 36, 48, and 60 months after radiotherapy. The primary endpoint was change from baseline in the bladder cancer subscale (BLCS) at 12 months. RESULTS AND LIMITATIONS: Data were available for 331 (92%) and 204 (93%) participants at baseline and for 192 (54%) and 114 (52%) at 12 months for the chemotherapy and radiotherapy comparisons, respectively. HRQoL declined at EoT (BLCS -5.06 [99% confidence interval: -6.12 to -4.00, p< 0.001]; overall FACT-B TOTAL score -8.22 [-10.76 to -5.68, p< 0.01]), recovering to baseline at 6 months and remaining similar to baseline subsequently. There was no significant difference between randomised groups at any time point. CONCLUSIONS: Immediately following (chemo)radiotherapy, a significant proportion of patients report declines in HRQoL, which improve to baseline after 6 months. Two-thirds of patients report stable or improved HRQoL on long-term follow-up. There is no evidence of impairment in HRQoL resulting from the addition of chemotherapy. PATIENT SUMMARY: Quality of life of bladder cancer patients treated with radiotherapy±chemotherapy deteriorates during treatment, but improves to at least pretreatment levels within 6 months. Addition of chemotherapy to radiotherapy does not affect patient-reported quality of life.

Androgen-regulated transcription of ESRP2 drives alternative splicing patterns in prostate cancer.

Prostate is the most frequent cancer in men. Prostate cancer progression is driven by androgen steroid hormones, and delayed by androgen deprivation therapy (ADT). Androgens control transcription by stimulating androgen receptor (AR) activity, yet also control pre-mRNA splicing through less clear mechanisms. Here we find androgens regulate splicing through AR-mediated transcriptional control of the epithelial-specific splicing regulator ESRP2. Both ESRP2 and its close paralog ESRP1 are highly expressed in primary prostate cancer. Androgen stimulation induces splicing switches in many endogenous ESRP2-controlled mRNA isoforms, including splicing switches correlating with disease progression. ESRP2 expression in clinical prostate cancer is repressed by ADT, which may thus inadvertently dampen epithelial splice programmes. Supporting this, treatment with the AR antagonist bicalutamide (Casodex) induced mesenchymal splicing patterns of genes including FLNB and CTNND1. Our data reveals a new mechanism of splicing control in prostate cancer with important implications for disease progression.

Obesity impacts the regulation of miR-10b and its targets in primary breast tumors.

BACKGROUND: Obesity increases breast cancer (BC) risk in post-menopausal women by mostly unknown molecular mechanisms which may partly be regulated by microRNAs (miRNAs). METHODS: We isolated RNA from paired benign and malignant biopsies from 83 BC patients and determined miRNA profiles in samples from 12 women at the extremes of the BMI distribution by RNA-seq. Candidates were validated in all samples. Associations between miR-10b expression and validated target transcript levels, and effects of targeted manipulation of miR-10b levels in a primary BC cell line on proliferation and invasion potential, were explored. RESULTS: Of the 148 miRNAs robustly expressed in breast tissues, the levels of miR-21, miR-10b, miR-451a, miR-30c, and miR-378d were significantly associated with presence of cancer. Of these, miR-10b showed a stronger down-regulation in the tumors of the obese subjects, as opposed to the lean. In ductal but not lobular tumors, significant inverse correlations were observed between the tumor levels of miR-10b and miR-30c and the mRNA levels of cancer-relevant target genes SRSF1, PIEZO1, MAPRE1, CDKN2A, TP-53 and TRA2B, as well as tumor grade. Suppression of miR-10b levels in BT-549 primary BC-derived cells increased cell proliferation and invasive capacity, while exogenous miR-10b mimic decreased invasion. Manipulation of miR-10b levels also inversely affected the mRNA levels of miR-10b targets BCL2L11, PIEZO1 and NCOR2. CONCLUSIONS: Our findings suggest that miR-10b may be a mediator between obesity and cancer in post-menopausal women, regulating several known cancer-relevant genes. MiR-10b expression may have diagnostic and therapeutic implications for the incidence and prognosis of BC in obese women.

The cancer-associated cell migration protein TSPAN1 is under control of androgens and its upregulation increases prostate cancer cell migration.

Cell migration drives cell invasion and metastatic progression in prostate cancer and is a major cause of mortality and morbidity. However the mechanisms driving cell migration in prostate cancer patients are not fully understood. We previously identified the cancer-associated cell migration protein Tetraspanin 1 (TSPAN1) as a clinically relevant androgen regulated target in prostate cancer. Here we find that TSPAN1 is acutely induced by androgens, and is significantly upregulated in prostate cancer relative to both normal prostate tissue and benign prostate hyperplasia (BPH). We also show for the first time, that TSPAN1 expression in prostate cancer cells controls the expression of key proteins involved in cell migration. Stable upregulation of TSPAN1 in both DU145 and PC3 cells significantly increased cell migration and induced the expression of the mesenchymal markers SLUG and ARF6. Our data suggest TSPAN1 is an androgen-driven contributor to cell survival and motility in prostate cancer.

Glycosylation is an Androgen-Regulated Process Essential for Prostate Cancer Cell Viability.

Steroid androgen hormones play a key role in the progression and treatment of prostate cancer, with androgen deprivation therapy being the first-line treatment used to control cancer growth. Here we apply a novel search strategy to identify androgen-regulated cellular pathways that may be clinically important in prostate cancer. Using RNASeq data, we searched for genes that showed reciprocal changes in expression in response to acute androgen stimulation in culture, and androgen deprivation in patients with prostate cancer. Amongst 700 genes displaying reciprocal expression patterns we observed a significant enrichment in the cellular process glycosylation. Of 31 reciprocally-regulated glycosylation enzymes, a set of 8 (GALNT7, ST6GalNAc1, GCNT1, UAP1, PGM3, CSGALNACT1, ST6GAL1 and EDEM3) were significantly up-regulated in clinical prostate carcinoma. Androgen exposure stimulated synthesis of glycan structures downstream of this core set of regulated enzymes including sialyl-Tn (sTn), sialyl Lewis(X) (SLe(X)), O-GlcNAc and chondroitin sulphate, suggesting androgen regulation of the core set of enzymes controls key steps in glycan synthesis. Expression of each of these enzymes also contributed to prostate cancer cell viability. This study identifies glycosylation as a global target for androgen control, and suggests loss of specific glycosylation enzymes might contribute to tumour regression following androgen depletion therapy.

The PI3K regulatory subunit gene PIK3R1 is under direct control of androgens and repressed in prostate cancer cells.

Androgen receptor (AR) signalling and the PI3K pathway mediate survival signals in prostate cancer, and have been shown to regulate each other by reciprocal negative feedback, such that inhibition of one activates the other. Understanding the reciprocal regulation of these pathways is important for disease management as tumour cells can adapt and survive when either single pathway is inhibited pharmacologically. We recently carried out genome-wide exon-specific profiling of prostate cancer cells to identify novel androgen-regulated transcriptional events. Here we interrogated this dataset for novel androgen-regulated genes associated with the PI3K pathway. We find that the PI3K regulatory subunits PIK3R1 (p85α) and PIK3R3 (p55γ) are direct targets of the AR which are rapidly repressed by androgens in LNCaP cells. Further characterisation revealed that the PIK3CA p110α catalytic subunit is also indirectly regulated by androgens at the protein level. We show that PIK3R1 mRNA is significantly under-expressed in prostate cancer (PCa) tissue, and provide data to suggest a context-dependent regulatory mechanism whereby repression of the p85α protein by the AR results in destabilisation of the PI3K p110α catalytic subunit and downstream PI3K pathway inhibition that functionally affects the properties of prostate cancer cells.

The androgen receptor controls expression of the cancer-associated sTn antigen and cell adhesion through induction of ST6GalNAc1 in prostate cancer.

Patterns of glycosylation are important in cancer, but the molecular mechanisms that drive changes are often poorly understood. The androgen receptor drives prostate cancer (PCa) development and progression to lethal metastatic castration-resistant disease. Here we used RNA-Seq coupled with bioinformatic analyses of androgen-receptor (AR) binding sites and clinical PCa expression array data to identify ST6GalNAc1 as a direct and rapidly activated target gene of the AR in PCa cells. ST6GalNAc1 encodes a sialytransferase that catalyses formation of the cancer-associated sialyl-Tn antigen (sTn), which we find is also induced by androgen exposure. Androgens induce expression of a novel splice variant of the ST6GalNAc1 protein in PCa cells. This splice variant encodes a shorter protein isoform that is still fully functional as a sialyltransferase and able to induce expression of the sTn-antigen. Surprisingly, given its high expression in tumours, stable expression of ST6GalNAc1 in PCa cells reduced formation of stable tumours in mice, reduced cell adhesion and induced a switch towards a more mesenchymal-like cell phenotype in vitro. ST6GalNAc1 has a dynamic expression pattern in clinical datasets, beingsignificantly up-regulated in primary prostate carcinoma but relatively down-regulated in established metastatic tissue. ST6GalNAc1 is frequently upregulated concurrently with another important glycosylation enzyme GCNT1 previously associated with prostate cancer progression and implicated in Sialyl Lewis X antigen synthesis. Together our data establishes an androgen-dependent mechanism for sTn antigen expression in PCa, and are consistent with a general role for the androgen receptor in driving important coordinate changes to the glycoproteome during PCa progression.

Randomized noninferiority trial of reduced high-dose volume versus standard volume radiation therapy for muscle-invasive bladder cancer: results of the BC2001 trial (CRUK/01/004).

PURPOSE: To test whether reducing radiation dose to uninvolved bladder while maintaining dose to the tumor would reduce side effects without impairing local control in the treatment of muscle-invasive bladder cancer. METHODS AND MATERIALS: In this phase III multicenter trial, 219 patients were randomized to standard whole-bladder radiation therapy (sRT) or reduced high-dose volume radiation therapy (RHDVRT) that aimed to deliver full radiation dose to the tumor and 80% of maximum dose to the uninvolved bladder. Participants were also randomly assigned to receive radiation therapy alone or radiation therapy plus chemotherapy in a partial 2 × 2 factorial design. The primary endpoints for the radiation therapy volume comparison were late toxicity and time to locoregional recurrence (with a noninferiority margin of 10% at 2 years). RESULTS: Overall incidence of late toxicity was less than predicted, with a cumulative 2-year Radiation Therapy Oncology Group grade 3/4 toxicity rate of 13% (95% confidence interval 8%, 20%) and no statistically significant differences between groups. The difference in 2-year locoregional recurrence free rate (RHDVRT - sRT) was 6.4% (95% confidence interval -7.3%, 16.8%) under an intention to treat analysis and 2.6% (-12.8%, 14.6%) in the "per-protocol" population. CONCLUSIONS: In this study RHDVRT did not result in a statistically significant reduction in late side effects compared with sRT, and noninferiority of locoregional control could not be concluded formally. However, overall low rates of clinically significant toxicity combined with low rates of invasive bladder cancer relapse confirm that (chemo)radiation therapy is a valid option for the treatment of muscle-invasive bladder cancer.

Radiotherapy with or without chemotherapy in muscle-invasive bladder cancer.

BACKGROUND: Radiotherapy is an alternative to cystectomy in patients with muscle-invasive bladder cancer. In other disease sites, synchronous chemoradiotherapy has been associated with increased local control and improved survival, as compared with radiotherapy alone. METHODS: In this multicenter, phase 3 trial, we randomly assigned 360 patients with muscle-invasive bladder cancer to undergo radiotherapy with or without synchronous chemotherapy. The regimen consisted of fluorouracil (500 mg per square meter of body-surface area per day) during fractions 1 to 5 and 16 to 20 of radiotherapy and mitomycin C (12 mg per square meter) on day 1. Patients were also randomly assigned to undergo either whole-bladder radiotherapy or modified-volume radiotherapy (in which the volume of bladder receiving full-dose radiotherapy was reduced) in a partial 2-by-2 factorial design (results not reported here). The primary end point was survival free of locoregional disease. Secondary end points included overall survival and toxic effects. RESULTS: At 2 years, rates of locoregional disease-free survival were 67% (95% confidence interval [CI], 59 to 74) in the chemoradiotherapy group and 54% (95% CI, 46 to 62) in the radiotherapy group. With a median follow-up of 69.9 months, the hazard ratio in the chemoradiotherapy group was 0.68 (95% CI, 0.48 to 0.96; P=0.03). Five-year rates of overall survival were 48% (95% CI, 40 to 55) in the chemoradiotherapy group and 35% (95% CI, 28 to 43) in the radiotherapy group (hazard ratio, 0.82; 95% CI, 0.63 to 1.09; P=0.16). Grade 3 or 4 adverse events were slightly more common in the chemoradiotherapy group than in the radiotherapy group during treatment (36.0% vs. 27.5%, P=0.07) but not during follow-up (8.3% vs. 15.7%, P=0.07). CONCLUSIONS: Synchronous chemotherapy with fluorouracil and mitomycin C combined with radiotherapy significantly improved locoregional control of bladder cancer, as compared with radiotherapy alone, with no significant increase in adverse events. (Funded by Cancer Research U.K.; BC2001 Current Controlled Trials number, ISRCTN68324339.).

Alterations in LMTK2, MSMB and HNF1B gene expression are associated with the development of prostate cancer.

BACKGROUND: Genome wide association studies (GWAS) have identified several genetic variants that are associated with prostate cancer. Most of these variants, like other GWAS association signals, are located in non-coding regions of potential candidate genes, and thus could act at the level of the mRNA transcript. METHODS: We measured the expression and isoform usage of seven prostate cancer candidate genes in benign and malignant prostate by real-time PCR, and correlated these factors with cancer status and genotype at the GWAS risk variants. RESULTS: We determined that levels of LMTK2 transcripts in prostate adenocarcinomas were only 32% of those in benign tissues (p = 3.2 x 10(-7)), and that an independent effect of genotype at variant rs6465657 on LMTK2 expression in benign (n = 39) and malignant tissues (n = 21) was also evident (P = 0.002). We also identified that whilst HNF1B(C) and MSMB2 comprised the predominant isoforms in benign tissues (90% and 98% of total HNF1B or MSMB expression), HNF1B(B) and MSMB1 were predominant in malignant tissue (95% and 96% of total HNF1B or MSMB expression; P = 1.7 x 10(-7) and 4 x 10(-4) respectively), indicating major shifts in isoform usage. CONCLUSIONS: Our results indicate that the amount or nature of mRNA transcripts expressed from the LMTK2, HNF1B and MSMB candidate genes is altered in prostate cancer, and provides further evidence for a role for these genes in this disorder. The alterations in isoform usage we detect highlights the potential importance of alternative mRNA processing and moderation of mRNA stability as potentially important disease mechanisms.