Development, maturation, and maintenance of human prostate inferred from somatic mutations

Clonal dynamics and mutation burden in healthy human prostate epithelium are relevant to prostate cancer. We sequenced whole genomes from 409 microdissections of normal prostate epithelium across 8 donors, using phylogenetic reconstruction with spatial mapping in a 59-year-old man's prostate to reconstruct tissue dynamics across the lifespan. Somatic mutations accumulate steadily at ∼16 mutations/year/clone, with higher rates in peripheral than peri-urethral regions. The 24-30 independent glandular subunits are established as rudimentary ductal structures during fetal development by 5-10 embryonic cells each. Puberty induces formation of further side and terminal branches by local stem cells disseminated throughout the rudimentary ducts during development. During adult tissue maintenance, clonal expansions have limited geographic scope and minimal migration. Driver mutations are rare in aging prostate epithelium, but the one driver we did observe generated a sizable intraepithelial clonal expansion. Leveraging unbiased clock-like mutations, we define prostate stem cell dynamics through fetal development, puberty, and aging.

Major Urological Cancer Surgery for Patients is Safe and Surgical Training Should Be Encouraged During the COVID-19 Pandemic: A Multicentre Analysis of 30-day Outcomes

COVID-19 has resulted in the deferral of major surgery for genitourinary (GU) cancers with the exception of cancers with a high risk of progression. We report outcomes for major GU cancer operations, namely radical prostatectomy (RP), radical cystectomy (RC), radical nephrectomy (RN), partial nephrectomy (PN), and nephroureterectomy performed at 13 major GU cancer centres across the UK between March 1 and May 5, 2020. A total of 598 such operations were performed. Four patients (0.7%) developed COVID-19 postoperatively. There was no COVID-19–related mortality at 30 d. A minimally invasive approach was used in 499 cases (83.4%). A total of 228 cases (38.1%) were described as training procedures. Training case status was not associated with a higher American Society of Anesthesiologists (ASA) score (p =  0.194) or hospital length of stay (LOS; p >  0.05 for all operation types). The risk of contracting COVID-19 was not associated with longer hospital LOS (p =  0.146), training case status (p =  0.588), higher ASA score (p =  0.295), or type of hospital site (p =  0.303). Our results suggest that major surgery for urological cancers remains safe and training should be encouraged during the ongoing COVID-19 pandemic provided appropriate countermeasures are taken. These real-life data are important for policy-makers and clinicians when counselling patients during the current pandemic.

Patient summary

We collected outcome data for major operations for prostate, bladder, and kidney cancers during the COVID-19 pandemic. These surgeries remain safe and training should be encouraged during the ongoing pandemic provided appropriate countermeasures are taken. Our real-life results are important for policy-makers and clinicians when counselling patients during the COVID-19 pandemic.

Age-associated mitochondrial DNA mutations cause metabolic remodelling that contributes to accelerated intestinal tumorigenesis

Oxidative phosphorylation (OXPHOS) defects caused by somatic mitochondrial DNA (mtDNA) mutations increase with age in human colorectal epithelium and are prevalent in colorectal tumours, but whether they actively contribute to tumorigenesis remains unknown. Here we demonstrate that mtDNA mutations causing OXPHOS defects are enriched during the human adenoma/carcinoma sequence, suggesting they may confer a metabolic advantage. To test this we deleted the tumour suppressor Apc in OXPHOS deficient intestinal stem cells in mice. The resulting tumours were larger than in control mice due to accelerated cell proliferation and reduced apoptosis. We show that both normal crypts and tumours undergo metabolic remodelling in response to OXPHOS deficiency by upregulating the de novo serine synthesis pathway (SSP). Moreover, normal human colonic crypts upregulate the SSP in response to OXPHOS deficiency prior to tumorigenesis. Our data show that age-associated OXPHOS deficiency causes metabolic remodelling that can functionally contribute to accelerated intestinal cancer development.

Ultra-sensitive refractive index sensor using CMOS plasmonic transducers on silicon photonic interferometric platform

Optical refractive-index sensors exploiting selective co-integration of plasmonics with silicon photonics has emerged as an attractive technology for biosensing applications that can unleash unprecedented performance breakthroughs that reaps the benefits of both technologies. However, towards this direction, a major challenge remains their integration using exclusively CMOS-compatible materials. In this context, herein, we demonstrate, for the first time to our knowledge, a CMOS-compatible plasmo-photonic Mach-Zehnder-interferometer (MZI) based on aluminum and Si3N4 waveguides, exhibiting record-high bulk sensitivity of 4764 nm/RIU with clear potential to scale up the bulk sensitivity values by properly engineering the design parameters of the MZI. The proposed sensor is composed of Si3N4 waveguides butt-coupled with an aluminum stripe in one branch to realize the sensing transducer. The reference arm is built by Si3N4 waveguides, incorporating a thermo-optic phase shifter followed by an MZI-based variable optical attenuation stage to maximize extinction ratio up to 38 dB, hence optimizing the overall sensing performance. The proposed sensor exhibits the highest bulk sensitivity among all plasmo-photonic counterparts, while complying with CMOS manufacturing standards, enabling volume manufacturing.

Propagation of human prostate tissue from induced pluripotent stem cells

Primary culture of human prostate organoids and patient‐derived xenografts is inefficient and has limited access to clinical tissues. This hampers their use for translational study to identify new treatments. To overcome this, we established a complementary approach where rapidly proliferating and easily handled induced pluripotent stem cells enabled the generation of human prostate tissue in vivo and in vitro. By using a coculture technique with inductive urogenital sinus mesenchyme, we comprehensively recapitulated in situ 3D prostate histology, and overcame limitations in the primary culture of human prostate stem, luminal and neuroendocrine cells, as well as the stromal microenvironment. This model now unlocks new opportunities to undertake translational studies of benign and malignant prostate disease.

Engineering Prostate Cancer from Induced Pluripotent Stem Cells-New Opportunities to Develop Preclinical Tools in Prostate and Prostate Cancer Studies

One of the key issues hampering the development of effective treatments for prostate cancer is the lack of suitable, tractable, and patient-specific in vitro models that accurately recapitulate this disease. In this review, we address the challenges of using primary cultures and patient-derived xenografts to study prostate cancer. We describe emerging approaches using primary prostate epithelial cells and prostate organoids and their genetic manipulation for disease modelling. Furthermore, the use of human prostate-derived induced pluripotent stem cells (iPSCs) is highlighted as a promising complimentary approach. Finally, we discuss the manipulation of iPSCs to generate 'avatars' for drug disease testing. Specifically, we describe how a conceptual advance through the creation of living biobanks of "genetically engineered cancers" that contain patient-specific driver mutations hold promise for personalised medicine.

Prostate cancer androgen receptor splice variant 7 biomarker study - a multicentre randomised feasibility trial of biomarker-guided personalised treatment in patients with advanced prostate cancer (the VARIANT trial) study protocol

INTRODUCTION

Prostate cancer is the most common male cancer with one in four developing non-curable metastatic disease. Initial treatment responses to hormonal therapies are transient and further management options lie between (1) further hormone therapy or (2) a non-hormonal approach involving additional chemotherapy or molecular radiotherapy (radium-223). There is no clear rationale for choosing between these mechanistically different treatment approaches. The biology of hormone resistance is driven through abnormal androgen receptor activity and we can assay this through a blood test measuring androgen receptor variant 7 (AR-V7) expression in circulating tumour cells. Despite increasing evidence supporting AR-V7's role as a prognostic marker, the clinical utility of such measures remains unknown in helping personalise treatment decisions.

METHODS AND DESIGN

The VARIANT feasibility trial is a pragmatic design, to be run over 18 months with participants randomised into the intervention arm receiving biomarker (AR-V7) guided clinical treatment and participants randomised into the control arm with conventional standard management (no biomarker guidance). AR-V7 positive participants (likely to be insensitive to further hormone treatment) will receive chemotherapy or in other cases radium-223 (where routinely available). Seventy male ≥18 years old participants with metastatic castrate resistant prostate cancer clinically indicated to proceed to further hormone therapy or chemotherapy, will be recruited from three National Health Service Trusts based in England, Scotland and Wales. The feasibility primary outcome is willingness of patients to be randomised and clinicians to recruit to a biomarker-based treatment strategy, with trial data informing the basis of a definitive and appropriately powered randomised control trial.

ETHICS AND DISSEMINATION

Formal ethics review was undertaken with a favourable opinion, through Wales NRES Committee 2 18/WA/0419. Findings to be disseminated through patient and professional organisations that have expressed their support, media outlets and peer-reviewed journal publication.

TRIAL REGISTRATION NUMBER

ISRCTN10246848; pre-results.

Photodynamic versus white light-guided treatment of non-muscle invasive bladder cancer: a study protocol for a randomised trial of clinical and cost-effectiveness

INTRODUCTION

Bladder cancer is the most frequently occurring tumour of the urinary system. Ta, T1 tumours and carcinoma in situ (CIS) are grouped as non-muscle invasive bladder cancer (NMIBC), which can be effectively treated by transurethral resection of bladder tumour (TURBT). There are limitations to the visualisation of tumours with conventional TURBT using white light illumination within the bladder. Incomplete resections occur from the failure to identify satellite lesions or the full extent of the tumour leading to recurrence and potential risk of disease progression. To improve complete resection, photodynamic diagnosis (PDD) has been proposed as a method that can enhance tumour detection and guide resection. The objective of the current research is to determine whether PDD-guided TURBT is better than conventional white light surgery and whether it is cost-effective.

METHODS AND ANALYSIS

PHOTO is a pragmatic multicentre randomised controlled trial (open parallel group, non-masked and superiority trial) comparing the intervention of PDD-guided TURBT with standard white light resection in newly diagnosed intermediate and high risk NMIBC within the UK National Health Service setting. Clinical effectiveness is measured with time to recurrence. Cost-effectiveness is assessed within trial via the calculation of incremental cost per recurrence avoided and incremental cost per quality-adjusted life per year gained over 3 years and over long term through a modelling exercise over patients' lifetime.

ETHICS AND DISSEMINATION

Formal ethics review was undertaken with a favourable opinion, in line with UK regulatory procedures (REC reference number: 14/NE/1062). If reductions in time to recurrence is associated with long-term patient benefits, the cost-effectiveness evaluation will provide further evidence to inform adoption of the technology. Findings will be shared in lay media such as patient and charity forums and will be presented at key meetings and published in academic literature.Trial registration number ISRCTN84013636.

The induction of core pluripotency master regulators in cancers defines poor clinical outcomes and treatment resistance

Stem cell characteristics have been associated with treatment resistance and poor prognosis across many cancer types. The ability to induce and regulate the pathways that sustain these characteristic hallmarks of lethal cancers in a novel in vitro model would greatly enhance our understanding of cancer progression and treatment resistance. In this work, we present such a model, based simply on applying standard pluripotency/embryonic stem cell media alone. Core pluripotency stem cell master regulators (OCT4, SOX2 and NANOG) along with epithelial–mesenchymal transition (EMT) markers (Snail, Slug, vimentin and N-cadherin) were induced in human prostate, breast, lung, bladder, colorectal, and renal cancer cells. RNA sequencing revealed pathways activated by pluripotency inducing culture that were shared across all cancers examined. These pathways highlight a potential core mechanism of treatment resistance. With a focus on prostate cancer, the culture-based induction of core pluripotent stem cell regulators was shown to promote survival in castrate conditions—mimicking first line treatment resistance with hormonal therapies. This acquired phenotype was shown to be mediated through the upregulation of iodothyronine deiodinase DIO2, a critical modulator of the thyroid hormone signalling pathway. Subsequent inhibition of DIO2 was shown to supress expression of prostate specific antigen, the cardinal clinical biomarker of prostate cancer progression and highlighted a novel target for clinical translation in this otherwise fatal disease. This study identifies a new and widely accessible simple preclinical model to recreate and explore underpinning pathways of lethal disease and treatment resistance.

Predominant Asymmetrical Stem Cell Fate Outcome Limits the Rate of Niche Succession in Human Colonic Crypts

Stem cell (SC) dynamics within the human colorectal crypt SC niche remain poorly understood, with previous studies proposing divergent hypotheses on the predominant mode of SC self-renewal and the rate of SC replacement. Here we use age-related mitochondrial oxidative phosphorylation (OXPHOS) defects to trace clonal lineages within human colorectal crypts across the adult life-course. By resolving the frequency and size distribution of OXPHOS-deficient clones, quantitative analysis shows that, in common with mouse, long-term maintenance of the colonic epithelial crypt relies on stochastic SC loss and replacement mediated by competition for limited niche access. We find that the colonic crypt is maintained by ~5 effective SCs. However, with a SC loss/replacement rate estimated to be slower than once per year, our results indicate that the vast majority of individual SC divisions result in asymmetric fate outcome. These findings provide a quantitative platform to detect and study deviations from human colorectal crypt SC niche homeostasis during the process of colorectal carcinogenesis.

Human ex vivo prostate tissue model system identifies ING3 as an oncoprotein

BACKGROUND

Although the founding members of the INhibitor of Growth (ING) family of histone mark readers, ING1 and ING2, were defined as tumour suppressors in animal models, the role of other ING proteins in cellular proliferation and cancer progression is unclear.

METHODS

We transduced ex vivo benign prostate hyperplasia tissues with inducible lentiviral particles to express ING proteins. Proliferation was assessed by H3S10phos immunohistochemistry (IHC). The expression of ING3 was assessed by IHC on a human prostate cancer tissue microarray (TMA). Gene expression was measured by DNA microarray and validated by real-time qPCR.

RESULTS

We found that ING3 stimulates cellular proliferation in ex vivo tissues, suggesting that ING3 could be oncogenic. Indeed, ING3 overexpression transformed normal human dermal fibroblasts. We observed elevated levels of ING3 in prostate cancer samples, which correlated with poorer patient survival. Consistent with an oncogenic role, gene-silencing experiments revealed that ING3 is required for the proliferation of breast, ovarian, and prostate cancer cells. Finally, ING3 controls the expression of an intricate network of cell cycle genes by associating with chromatin modifiers and the H3K4me3 mark at transcriptional start sites.

CONCLUSIONS

Our investigations create a shift in the prevailing view that ING proteins are tumour suppressors and redefine ING3 as an oncoprotein.

Laparoscopic renal surgery is here to stay

Objectives

To review the current literature comparing the outcomes of renal surgery via open, laparoscopic and robotic approaches.

Materials and methods

A comprehensive literature search was performed on PubMed, MEDLINE and Ovid, to look for studies comparing outcomes of renal surgery via open, laparoscopic, and robotic approaches.

Results

Limited good-quality evidence suggests that all three approaches result in largely comparable functional and oncological outcomes. Both laparoscopic and robotic approaches result in less blood loss, analgesia requirement, with a shorter hospital stay and recovery time, with similar complication rates when compared with the open approach. Robotic renal surgeries have not shown any significant clinical benefit over a laparoscopic approach, whilst the associated cost is significantly higher.

Conclusion

With the high cost and lack of overt clinical benefit of the robotic approach, laparoscopic renal surgery will likely continue to remain relevant in treating various urological pathologies.

Urothelial Carcinoma Stem Cells: Current Concepts, Controversies, and Methods

Cancer stem cells are defined as a self-renewing and self-protecting subpopulation of cancer cells able to differentiate into morphologically and functionally diverse cancer cells with a limited lifespan. To purify cancer stem cells, two basic approaches can be applied, the marker-based approach employing various more of less-specific cell surface marker molecules and a marker-free approach largely based on various self-protection mechanisms. Within the context of urothelial carcinoma, both methods could find use. The cell surface markers have been mainly derived from the urothelial basal cell, a probable cell of origin of muscle-invasive urothelial carcinoma, with CD14, CD44, CD90, and 67LR representing successful examples of this strategy. The marker-free approaches involve side population sorting, for which a detailed protocol is provided, as well as the Aldefluor assay, which rely on a specific overexpression of efflux pumps or the detoxification enzyme aldehyde dehydrogenase, respectively, in stem cells. These assays have been applied to both non-muscle-invasive and muscle-invasive bladder cancer samples and cell lines. Urothelial carcinoma stem cells feature a pronounced heterogeneity as to their molecular stemness mechanisms. Several aspects of urothelial cancer stem cell biology could enter translational development rather soon, e.g., a specific CD44⁺-derived gene expression signature able to identify non-muscle-invasive bladder cancer patients with a high risk of progression, or deciphering a mechanism responsible for repopulating activity of urothelial carcinoma stem cells within the context of therapeutic resistance.

A Unifying Theory of Branching Morphogenesis

The morphogenesis of branched organs remains a subject of abiding interest. Although much is known about the underlying signaling pathways, it remains unclear how macroscopic features of branched organs, including their size, network topology, and spatial patterning, are encoded. Here, we show that, in mouse mammary gland, kidney, and human prostate, these features can be explained quantitatively within a single unifying framework of branching and annihilating random walks. Based on quantitative analyses of large-scale organ reconstructions and proliferation kinetics measurements, we propose that morphogenesis follows from the proliferative activity of equipotent tips that stochastically branch and randomly explore their environment but compete neutrally for space, becoming proliferatively inactive when in proximity with neighboring ducts. These results show that complex branched epithelial structures develop as a self-organized process, reliant upon a strikingly simple but generic rule, without recourse to a rigid and deterministic sequence of genetically programmed events.

•

Branching morphogenesis follows conserved statistical rules in multiple organs

•

Ductal tips grow and branch as default state and stop dividing in high-density regions

•

Model reproduces quantitatively organ properties in a parameter-free manner

•

Shows that complex organ formation proceeds in a stochastic, self-organized manner

Corrigendum: Can we deliver randomized trials of focal therapy in prostate cancer?

This corrects the article DOI: 10.1038/nrclinonc.2014.44.

Multipotent Basal Stem Cells, Maintained in Localized Proximal Niches, Support Directed Long-Ranging Epithelial Flows in Human Prostates

Sporadic mitochondrial DNA mutations serve as clonal marks providing access to the identity and lineage potential of stem cells within human tissues. By combining quantitative clonal mapping with 3D reconstruction of adult human prostates, we show that multipotent basal stem cells, confined to discrete niches in juxta-urethral ducts, generate bipotent basal progenitors in directed epithelial migration streams. Basal progenitors are then dispersed throughout the entire glandular network, dividing and differentiating to replenish the loss of apoptotic luminal cells. Rare lineage-restricted luminal stem cells, and their progeny, are confined to proximal ducts and provide only minor contribution to epithelial homeostasis. In situ cell capture from clonal maps identified delta homolog 1 (DLK1) enrichment of basal stem cells, which was validated in functional spheroid assays. This study establishes significant insights into niche organization and function of prostate stem and progenitor cells, with implications for disease.

High-Risk Non-Muscle-Invasive Bladder Cancer-Therapy Options During Intravesical BCG Shortage

Bladder cancer is the second commonest urinary tract malignancy with 70–80 % being non-muscle invasive (NMIBC) at diagnosis. Patients with high-risk NMIBC (T1/Tis, with high grade/G3, or CIS) represent a challenging group as they are at greater risk of recurrence and progression. Intravesical Bacilli Calmette-Guerin (BCG) is commonly used as first line therapy in this patient group but there is a current worldwide shortage. BCG has been shown to reduce recurrence in high-risk NMIBC and is more effective that other intravesical agents including mitomycin C, epirubicin, interferon-alpha and gemcitabine. Primary cystectomy offers a high change of cure in this cohort (80–90 %) and is a more radical treatment option which patients need to be counselled carefully about. Bladder thermotherapy and electromotive drug administration with mitomycin C are alternative therapies with promising short-term results although long-term follow-up data are lacking.

Functional networks inference from rule-based machine learning models

BACKGROUND

Functional networks play an important role in the analysis of biological processes and systems. The inference of these networks from high-throughput (-omics) data is an area of intense research. So far, the similarity-based inference paradigm (e.g. gene co-expression) has been the most popular approach. It assumes a functional relationship between genes which are expressed at similar levels across different samples. An alternative to this paradigm is the inference of relationships from the structure of machine learning models. These models are able to capture complex relationships between variables, that often are different/complementary to the similarity-based methods.

RESULTS

We propose a protocol to infer functional networks from machine learning models, called FuNeL. It assumes, that genes used together within a rule-based machine learning model to classify the samples, might also be functionally related at a biological level. The protocol is first tested on synthetic datasets and then evaluated on a test suite of 8 real-world datasets related to human cancer. The networks inferred from the real-world data are compared against gene co-expression networks of equal size, generated with 3 different methods. The comparison is performed from two different points of view. We analyse the enriched biological terms in the set of network nodes and the relationships between known disease-associated genes in a context of the network topology. The comparison confirms both the biological relevance and the complementary character of the knowledge captured by the FuNeL networks in relation to similarity-based methods and demonstrates its potential to identify known disease associations as core elements of the network. Finally, using a prostate cancer dataset as a case study, we confirm that the biological knowledge captured by our method is relevant to the disease and consistent with the specialised literature and with an independent dataset not used in the inference process.

AVAILABILITY

The implementation of our network inference protocol is available at: http://ico2s.org/software/funel.html.

Evaluation of early response to neoadjuvant chemotherapy in muscle-invasive bladder cancer using dynamic contrast-enhanced MRI and diffusion weighted MRI: MARBLE study

403

Background: Functional imaging techniques which evaluate early treatment responses may identify non-responders who would benefit from a switch in therapy. This is a prospective feasibility study of serial diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI scanning in patients undergoing neoadjuvant chemotherapy for muscle-invasive bladder cancer. Methods: Scans were performed before and during chemotherapy (10-17 days after the first and second cycles). A repeatability DW-MRI scan was acquired on the first visit. Regions-of-interest (ROI) encompassing the entire tumour were defined. Analysis of MRI parameters was undertaken and related to findings from the routine restaging CT scan performed after 3 cycles of chemotherapy. Results: 10/16 patients were male, median age 59 years, 14/16 had T3/4 disease, and 5/16 were node positive. 10/16 have completed 3 or 4 cycles of chemotherapy to date and attended for the restaging CT scan. Radiological response was identified in all cases. In the DW-MRI analysis there was no significant difference in mean tumour ADC or tumour volume between baseline and repeatability scans (mean ADC 1.19 and 1.2 respectively, n=16). Visual assessment showed a fall in contrast agent uptake within the primary bladder tumour after treatment. Conclusions: The scanning protocols enabled visualisation of the bladder tumours and derivation of kinetic parameters. DW-MRI measurements were comparable between baseline and repeat scan, suggesting that a change in ADC was more likely to be attributable to treatment response or disease progression than measurement error or inherent variation. Statistically significant rises in mean ADC and decreases in tumour volume were observed early in the treatment pathway. No patients progressed on treatment in this study. Larger studies of DCE and DW-MRI as surrogate response imaging biomarkers in bladder cancer are recommended. Clinical trial information: Study ID 14489. [Table: see text]

Delays in the diagnosis and treatment of muscle invasive bladder cancer: A pilot project mapping the pathway

Background:

The patient pathway for muscle invasive bladder cancer (MIBC) is multidisciplinary. Trans-urethral resection of bladder tumour (TURBT) counts as the first definitive treatment and subsequent definitive therapy thereafter is often delayed, which may adversely affect outcome. We elected to scrutinise the management pathway in detail to understand these delays and improve the patient experience.

Method:

A retrospective mapping analysis was conducted on 17 patients with MIBC. The causes of any delays and measures to avoid these were identified. A prospective study of 17 patients with MIBC was then undertaken to see if the strategies used to re-engineer the patient care pathway had been effective.

Result:

The median time from GP referral to first appointment was 9 days (range: 1–37) and from TURBT to subsequent radical treatment was 75 days (range: 27–105) in keeping with published literature. The median time for a referral letter from urology to oncology following MDT was 15 days. We therefore modified the MDT proforma to use as a formal referral, and a project manager proactively managed the patient pathway. Capacity issues were addressed by protecting clinical slots for bladder patients and establishing monthly evening clinics. After implementing the strategies, the median days from first appointment to TURBT improved from 31 to 23 days and time from TURBT to subsequent treatment improved from 75 to 66 days. The time from MDT referral to being seen by an oncologist or urologist significantly reduced from 32 to 15 days.

Conclusion:

Retrospective analysis identified delays between initial TURBT to definitive therapy and strategies adopted to reduce these were effective. TURBT is a diagnostic process and if acknowledged as first treatment results in delays of what is the definitive treatment. We found the initial diagnostic pathway to work well but non-muscle invasive bladder cancer (NMIBC) and MIBC are then managed very differently and warrant two separate pathways.

Using induced pluripotent stem cells as a tool for modelling carcinogenesis

Cancer is a highly heterogeneous group of diseases that despite improved treatments remain prevalent accounting for over 14 million new cases and 8.2 million deaths per year. Studies into the process of carcinogenesis are limited by lack of appropriate models for the development and pathogenesis of the disease based on human tissues. Primary culture of patient samples can help but is difficult to grow for a number of tissues. A potential opportunity to overcome these barriers is based on the landmark study by Yamanaka which demonstrated the ability of four factors; Oct4, Sox2, Klf4, and c-Myc to reprogram human somatic cells in to pluripotency. These cells were termed induced pluripotent stem cells (iPSCs) and display characteristic properties of embryonic stem cells. This technique has a wide range of potential uses including disease modelling, drug testing and transplantation studies. Interestingly iPSCs also share a number of characteristics with cancer cells including self-renewal and proliferation, expression of stem cell markers and altered metabolism. Recently, iPSCs have been generated from a number of human cancer cell lines and primary tumour samples from a range of cancers in an attempt to recapitulate the development of cancer and interrogate the underlying mechanisms involved. This review will outline the similarities between the reprogramming process and carcinogenesis, and how these similarities have been exploited to generate iPSC models for a number of cancers.

A novel model of urinary tract differentiation, tissue regeneration, and disease: reprogramming human prostate and bladder cells into induced pluripotent stem cells

BACKGROUND

Primary culture and animal and cell-line models of prostate and bladder development have limitations in describing human biology, and novel strategies that describe the full spectrum of differentiation from foetal through to ageing tissue are required. Recent advances in biology demonstrate that direct reprogramming of somatic cells into pluripotent embryonic stem cell (ESC)-like cells is possible. These cells, termed induced pluripotent stem cells (iPSCs), could theoretically generate adult prostate and bladder tissue, providing an alternative strategy to study differentiation.

OBJECTIVE

To generate human iPSCs derived from normal, ageing, human prostate (Pro-iPSC), and urinary tract (UT-iPSC) tissue and to assess their capacity for lineage-directed differentiation.

DESIGN, SETTING, AND PARTICIPANTS

Prostate and urinary tract stroma were transduced with POU class 5 homeobox 1 (POU5F1; formerly OCT4), SRY (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (gut) (KLF4), and v-myc myelocytomatosis viral oncogene homolog (avian) (MYC, formerly C-MYC) genes to generate iPSCs.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The potential for differentiation into prostate and bladder lineages was compared with classical skin-derived iPSCs. The student t test was used.

RESULTS AND LIMITATIONS

Successful reprogramming of prostate tissue into Pro-iPSCs and bladder and ureter into UT-iPSCs was demonstrated by characteristic ESC morphology, marker expression, and functional pluripotency in generating all three germ-layer lineages. In contrast to conventional skin-derived iPSCs, Pro-iPSCs showed a vastly increased ability to generate prostate epithelial-specific differentiation, as characterised by androgen receptor and prostate-specific antigen induction. Similarly, UT-iPSCs were shown to be more efficient than skin-derived iPSCs in undergoing bladder differentiation as demonstrated by expression of urothelial-specific markers: uroplakins, claudins, and cytokeratin; and stromal smooth muscle markers: α-smooth-muscle actin, calponin, and desmin. These disparities are likely to represent epigenetic differences between individual iPSC lines and highlight the importance of organ-specific iPSCs for tissue-specific studies.

CONCLUSIONS

IPSCs provide an exciting new model to characterise mechanisms regulating prostate and bladder differentiation and to develop novel approaches to disease modelling. Regeneration of bladder cells also provides an exceptional opportunity for translational tissue engineering.