Reprint of: Stromogenic prostatic carcinoma pattern (carcinomas with reactive stromal grade 3) in needle biopsies predicts biochemical recurrence-free survival in patients after radical prostatectomy

Quantification of collagen content and stromal cellularity within reactive stroma is predictive of prostate cancer biochemical recurrence and specific death

Semiquantitative reactive stromal grading has been shown to be a predictor of biochemical recurrence and prostate cancer (PCa) specific death. It has been extensively validated. In this study we tested novel technologies to introduce quantitative measures of host response, in particular collagen content and stromal cellularity. We use 3 large retrospective cohorts, the Baylor College of Medicine cohort, the Brady cohort and the Pound cohort. Slides were stained and digitized using image deconvolution and analyzed using image segmentation and image analyses. PicroSirius red stain histochemical stains were used for collagen quantification. Area of cancer and stroma were measured independently, without regard to quality of stroma. Cellularity, in each compartment, was measured using image deconvolution, image segmentation and image analysis. Two biomarkers were tested in 3 independent cohorts with two endpoints, biochemical recurrence and prostate cancer specific death. Stromal cellularity (qCollCell) and stromal collagen area (qCollArea) are independently predictive biochemical recurrence in the Hopkins Brady cohort, particularly in Gleason 6-7 patients. Multivariate analysis demonstrated that increased stroma cellularity (qCollCell) was a significant predictor of PCa specific death, when compared to an established model of PCa, in the Baylor cohort. Stromal collagen (qCollArea) independently predicts PCa-specific death in the Hopkins Pound cohort. The introduction of a computerized quantitative test of the host response increases the probability that this test will be reproducible in other cohorts. The ability to improve prediction of prostate cancer specific death might lie in the study of the host and its response.

Low Tumor-to-Stroma Ratio Reflects Protective Role of Stroma against Prostate Cancer Progression

Tumor-to-stroma ratio (TSR) is a prognostic factor that expresses the relative amounts of tumor and intratumoral stroma. In this study, its clinical and molecular relevance was evaluated in prostate cancer (PCa). The feasibility of automated quantification was tested in digital scans of tissue microarrays containing 128 primary tumors from 72 PCa patients stained immunohistochemically for epithelial cell adhesion molecule (EpCAM), followed by validation in a cohort of 310 primary tumors from 209 PCa patients. In order to investigate the gene expression differences between tumors with low and high TSR, we applied multigene expression analysis (nCounter® PanCancer Progression Panel, NanoString) of 42 tissue samples. TSR scores were categorized into low (<1 TSR) and high (≥1 TSR). In the pilot cohort, 31 patients (43.1%) were categorized as low and 41 (56.9%) as high TSR score, whereas 48 (23.0%) patients from the validation cohort were classified as low TSR and 161 (77.0%) as high. In both cohorts, high TSR appeared to indicate the shorter time to biochemical recurrence in PCa patients (Log-rank test, p = 0.04 and p = 0.01 for the pilot and validation cohort, respectively). Additionally, in the multivariate analysis of the validation cohort, TSR predicted BR independent of other factors, i.e., pT, pN, and age (p = 0.04, HR 2.75, 95%CI 1.07-7.03). Our data revealed that tumors categorized into low and high TSR score show differential expression of various genes; the genes upregulated in tumors with low TSR score were mostly associated with extracellular matrix and cell adhesion regulation. Taken together, this study shows that high stroma content can play a protective role in PCa. Automatic EpCAM-based quantification of TSR might improve prognostication in personalized medicine for PCa.

Multiphoton Microscopy for Identifying Collagen Signatures Associated with Biochemical Recurrence in Prostate Cancer Patients

Prostate cancer is a heterogeneous disease that remains dormant for long periods or acts aggressively with poor clinical outcomes. Identifying aggressive prostate tumor behavior using current glandular-focused histopathological criteria is challenging. Recent evidence has implicated the stroma in modulating prostate tumor behavior and in predicting post-surgical outcomes. However, the emergence of stromal signatures has been limited, due in part to the lack of adoption of imaging modalities for stromal-specific profiling. Herein, label-free multiphoton microscopy (MPM), with its ability to image tissue with stromal-specific contrast, is used to identify prostate stromal features associated with aggressive tumor behavior and clinical outcome. MPM was performed on unstained prostatectomy specimens from 59 patients and on biopsy specimens from 17 patients with known post-surgery recurrence status. MPM-identified collagen content, organization, and morphological tumor signatures were extracted for each patient and screened for association with recurrent disease. Compared to tumors from patients whose disease did not recur, tumors from patients with recurrent disease exhibited higher MPM-identified collagen amount and collagen fiber intensity signal and width. Our study shows an association between MPM-identified stromal collagen features of prostate tumors and post-surgical disease recurrence, suggesting their potential for prostate cancer risk assessment.

The Tumor Microenvironment and Immunotherapy in Prostate and Bladder Cancer

Bladder cancer has been successfully treated with immunotherapy, whereas prostate cancer is a cold tumor with inadequate immune-related treatment response. A greater understanding of the tumor microenvironment and methods for harnessing the immune system to address tumor growth will be needed to improve immunotherapies for both prostate and bladder cancer. Here, we provide an overview of prostate and bladder cancer, including fundamental aspects of the disease and treatment, the elaborate cellular makeup of the tumor microenvironment, and methods for exploiting relevant pathways to develop more effective treatments.

Stromal reactivity differentially drives tumour cell evolution and prostate cancer progression

Prostate cancer (PCa) progression is a complex eco-evolutionary process driven by the feedback between evolving tumour cell phenotypes and microenvironmentally driven selection. To better understand this relationship, we used a multiscale mathematical model that integrates data from biology and pathology on the microenvironmental regulation of PCa cell behaviour. Our data indicate that the interactions between tumour cells and their environment shape the evolutionary dynamics of PCa cells and explain overall tumour aggressiveness. A key environmental determinant of this aggressiveness is the stromal ecology, which can be either inhibitory, highly reactive (supportive) or non-reactive (neutral). Our results show that stromal ecology correlates directly with tumour growth but inversely modulates tumour evolution. This suggests that aggressive, environmentally independent PCa may be a result of poor stromal ecology, supporting the concept that purely tumour epithelium-centric metrics of aggressiveness may be incomplete and that incorporating markers of stromal ecology would improve prognosis.

Fibroblast as a critical stromal cell type determining prognosis in prostate cancer

BACKGROUND

Tumor stroma associates with prostate cancer (PCa) progression, but its specific cellular composition and association to patient survival outcome have not been characterized.

METHODS

We analyzed stromal composition in human PCa using multiplex immunohistochemistry and quantitative, high-resolution image analysis in two retrospective, formalin-fixed paraffin embedded observational clinical cohorts (Cohort I, n = 117; Cohort II, n = 340) using PCa-specific mortality as outcome measurement.

RESULTS

A high proportion of fibroblasts associated with aggressive disease and castration-resistant prostate cancer (CRPC). In a multivariate analysis, increase in fibroblast proportion predicted poor cancer-specific outcome independently in the two clinical cohorts studied.

CONCLUSIONS

Fibroblasts were the most important cell type in determining prognosis in PCa and associated with CRPC. Thus, the stromal composition could be critically important in developing diagnostic and therapeutic approaches to aggressive prostate cancer.

PTEN loss in prostatic adenocarcinoma correlates with specific adverse histologic features (intraductal carcinoma, cribriform Gleason pattern 4 and stromogenic carcinoma)

BACKGROUND

The loss of PTEN tumor suppressor gene is one of the most common somatic genetic aberrations in prostate cancer (PCa) and is frequently associated with high-risk disease. Deletion or mutation of at least one PTEN allele has been reported to occur in 20% to 40% of localized PCa and up to 60% of metastases. The goal of this study was to determine if somatic alteration detected by PTEN immunohistochemical loss of expression is associated with specific histologic features.

METHODS

Two hundred sixty prostate core needle biopsies with PCa were assessed for PTEN loss using an analytically validated immunohistochemical assay. Blinded to PTEN status, each tumor was assessed for the Grade Group (GG) and the presence or absence of nine epithelial features. Presence of stromogenic PCa was also assessed and defined as grade 3 reactive tumor stroma as previously described: the presence of carcinoma associated stromal response with epithelial to stroma ratio of greater than 50% reactive stroma.

RESULTS

Eight-eight (34%) cases exhibited PTEN loss while 172 (66%) had intact PTEN. PTEN loss was significantly (P < 0.05) associated with increasing GG, poorly formed glands (74% of total cases with loss vs 49% of intact), and three well-validated unfavorable pathological features: intraductal carcinoma of the prostate (IDC-P) (69% of total cases with loss vs 12% of intact), cribriform Gleason pattern 4 (38% of total cases with loss vs 10% of intact) and stromogenic PCa (23% of total cases with loss vs 6% of intact). IDC-P had the highest relative risk (4.993, 95% confidence interval, 3.451-7.223, P < 0.001) for PTEN loss. At least one of these three unfavorable pathological features were present in 67% of PCa exhibiting PTEN loss, while only 11% of PCa exhibited PTEN loss when none of these three unfavorable pathological features were present.

CONCLUSIONS

PCa with PTEN loss demonstrates a strong correlation with known unfavorable histologic features, particularly IDC-P. This is the first study showing the association of PTEN loss with stromogenic PCa.

Moving Beyond Gleason Scoring

Context.—

The combination of grading and staging is the basis of current standard of care for prediction for most cancers. D. F. Gleason created the current prostate cancer (PCa) grading system. This system has been modified several times. Molecular data have been added. Currently, all grading systems are cancer-cell based.

Objective.—

To review the literature available on host response measures as reactive stroma grading and stromogenic carcinoma, and their predictive ability for PCa biochemical recurrence and PCa-specific death.

Data Sources.—

Our own experience has shown that reactive stroma grading and the subsequently binarized system (stromogenic carcinoma) can independently predict biochemical recurrence and/or PCa-specific death, particularly in patients with a Gleason score of 6 or 7. Stromogenic carcinoma has been validated by 4 other independent groups in at least 3 continents.

Conclusions.—

Broders grading and Dukes staging have been combined to form the most powerful prognostic tools in standard of care. The time has come for us to incorporate measures of host response (stromogenic carcinoma) into the arsenal of elements we use to predict cancer survival, without abandoning what we know works. These data also suggest that our current definition of PCa might need some revision.

Biopsy proportion of tumour predicts pathological tumour response and benefit from chemotherapy in resectable oesophageal carcinoma: results from the UK MRC OE02 trial

Background

Neoadjuvant chemotherapy followed by surgery is the standard of care for UK patients with locally advanced resectable oesophageal carcinoma (OeC). However, not all patients benefit from multimodal treatment and there is a clinical need for biomarkers which can identify chemotherapy responders. This study investigated whether the proportion of tumour cells per tumour area (PoT) measured in the pre-treatment biopsy predicts chemotherapy benefit for OeC patients.

Patients and methods

PoT was quantified using digitized haematoxylin/eosin stained pre-treatment biopsy slides from 281 OeC patients from the UK MRC OE02 trial (141 treated by surgery alone (S); 140 treated by 5-fluorouracil/cisplatin followed by surgery (CS)). The relationship between PoT and clinicopathological data including tumour regression grade (TRG), overall survival and treatment interaction was investigated.

Results

PoT was associated with chemotherapy benefit in a non-linear fashion (test for interaction, P=0.006). Only patients with a biopsy PoT between 40% and 70% received a significant survival benefit from neoadjuvant chemotherapy (N=129; HR (95%CI):1.94 (1.39-2.71), unlike those with lower or higher PoT (PoT<40%, N=39, HR:1.25 (0.66-2.35); PoT>70% (N=28, HR:0.65 (0.36-1.18)). High pre-treatment PoT was related to lack of primary tumour regression (TRG 4 or 5), P=0.0402.

Conclusions

This is the first study to identify in a representative subgroup of OeC patients from a large randomized phase III trial that the proportion of tumour in the pre-chemotherapy biopsy predicts benefit from chemotherapy and may be a clinically useful biomarker for patient treatment stratification.

Proportion of tumour is a novel biomarker which can be measured in the pre-treatment diagnostic biopsy and which may enable the identification of chemotherapy responders and non-responders among patients with oesophageal carcinoma. Proportion of tumour could easily become part of the routine reporting of oesophageal cancer biopsies and may aid in managing patients with borderline resectable cancer.

Interaction of prostate carcinoma-associated fibroblasts with human epithelial cell lines in vivo

Stromal-epithelial interactions play a crucial and poorly understood role in carcinogenesis and tumor progression. Mesenchymal-epithelial interactions have a long history of research in relation to the development of organs. Models designed to study development are often also applicable to studies of benign and malignant disease. Tumor stroma is a complex mixture of cells that includes a fibroblastic component often referred to as cancer-associated fibroblasts (CAF), desmoplasia or "reactive" stroma. Here we discuss the history of, and approaches to, understanding these interactions with particular reference to prostate cancer and to in vivo modeling using human cells and tissues. A series of studies have revealed a complex mixture of signaling molecules acting both within the stromal tissue and between the stromal and epithelial tissues. We are starting to understand the interactions of some of these pathways, however the work is still ongoing. This area of research provide a basis for new medical approaches aimed at stabilizing early stage cancers rendering them chronic rather than acute problems. Such work is especially relevant to slow growing tumors found in older patients, a class that would include many prostate cancers.

Reactive stroma component COL6A1 is upregulated in castration-resistant prostate cancer and promotes tumor growth

Castration-resistant prostate cancer (CRPC) remains the most critical challenge in the clinical management of prostate cancer (PCa). Reactive stromal changes in PCa are likely involved in the emergence of CRPC. In the present study, we identified a novel oncogene termed COL6A1 which was upregulated in the reactive stroma of CRPC. We established an androgen-independent LNCaP (LNCaP-AI) cell line in steroid-reduced (SR) medium within 2 months. We examined COL6A1 expression with western blot during the LNCaP-AI induction, and studied the function of COL6A1 in vitro and in vivo. Immunohistochemical staining of COL6A1 was performed in ten pairs of androgen-sensitive PCa and CRPC samples. We demonstrated that COL6A1 expression was markedly increased in LNCaP-AI cells and CRPC tissues compared with LNCaP cells and paired androgen-sensitive PCa specimens. In vitro, COL6A1 knockdown resulted in G1-S cell cycle arrest and descended vitality. Overexpression of COL6A1 was associated with accelerated S phase entry and elevated vitality in prostate cancer cells. COL6A1 also promoted tumorigenesis of LNCaP cells in vivo. Taken together, these data suggest an important role of COL6A1 in the molecular etiology of castration-resistant prostate cancer, and support the potential use of COL6A1 in CRPC therapy.

The role of androgen receptor expression in the curative treatment of prostate cancer with radiotherapy: a pilot study

The androgen receptor (AR) and its signaling pathway play an important role in the development and progression of prostate cancer (PCa). In the setting of primary treatment of PCa with radiotherapy (RT), where the AR can be expected to be of more importance, studies evaluating the AR expression are lacking. The goal of this research is to evaluate AR protein expression in hormone-naive PCa patients treated by RT and investigate its possible prognostic role. Primary biopsy samples of 18 patients treated with primary RT were analyzed including the corresponding clinical information. AR protein expression of the tumor epithelium (with highest Gleason pattern) and the surrounding stroma was quantified using the Quick score for steroid receptors. The differential expression between epithelium and stroma, respectively, between tumor and normal tissue (ΔTumor − ΔBenign >2 versus ≤2), was predictive for clinical progression-free survival in the biopsy samples (P = 0.014). Preliminary results of this research show already a promising role of differential AR expression in predicting clinical relapse after PCa treatment with primary EBRT. Further research is needed to validate these findings. Hopefully this can lead to a better understanding of PCa evolution and eventually lead to better therapy strategies.

Extracellular Hsp90 mediates an NF-κB dependent inflammatory stromal program: implications for the prostate tumor microenvironment

BACKGROUND

The tumor microenvironment (TME) plays an essential role in supporting and promoting tumor growth and progression. An inflammatory stroma is a widespread hallmark of the prostate TME, and prostate tumors are known to co-evolve with their reactive stroma. Cancer-associated fibroblasts (CAFs) within the reactive stroma play a salient role in secreting cytokines that contribute to this inflammatory TME. Although a number of inflammatory mediators have been identified, a clear understanding of key factors initiating the formation of reactive stroma is lacking.

METHODS

We explored whether tumor secreted extracellular Hsp90 alpha (eHsp90α) may initiate a reactive stroma. Prostate stromal fibroblasts (PrSFs) were exposed to exogenous Hsp90α protein, or to conditioned medium (CM) from eHsp90α-expressing prostate cancer cells, and evaluated for signaling, motility, and expression of prototypic reactive markers. In tandem, ELISA assays were utilized to characterize Hsp90α-mediated secreted factors.

RESULTS

We report that exposure of PrSFs to eHsp90 upregulates the transcription and protein secretion of IL-6 and IL-8, key inflammatory cytokines known to play a causative role in prostate cancer progression. Cytokine secretion was regulated in part via a MEK/ERK and NF-κB dependent pathway. Secreted eHsp90α also promoted the rapid and durable activation of the oncogenic inflammatory mediator signal transducer and activator of transcription (STAT3). Finally, eHsp90 induced the expression of MMP-3, a well-known mediator of fibrosis and the myofibroblast phenotype.

CONCLUSIONS

Our results provide compelling support for eHsp90α as a transducer of signaling events culminating in an inflammatory and reactive stroma, thereby conferring properties associated with prostate cancer progression.

Genes upregulated in prostate cancer reactive stroma promote prostate cancer progression in vivo

PURPOSE

Marked reactive stroma formation is associated with poor outcome in clinically localized prostate cancer. We have previously identified genes with diverse functions that are upregulated in reactive stroma. This study tests the hypothesis that expression of these genes in stromal cells enhances prostate cancer growth in vivo.

EXPERIMENTAL DESIGN

The expression of reactive stroma genes in prostate stromal cell lines was evaluated by reverse transcriptase (RT)-PCR and qRT-PCR. Genes were knocked down using stable expression of short-hairpin RNAs (shRNA) and the impact on tumorigenesis assessed using the differential reactive stroma (DRS) system, in which prostate stromal cell lines are mixed with LNCaP prostate cancer cells and growth as subcutaneous xenografts assessed.

RESULTS

Nine of 10 reactive stroma genes tested were expressed in one or more prostate stromal cell lines. Gene knockdown of c-Kit, Wnt10B, Bmi1, Gli2, or COMP all resulted in decreased tumorigenesis in the DRS model. In all tumors analyzed, angiogenesis was decreased and there were variable effects on proliferation and apoptosis in the LNCaP cells. Wnt10B has been associated with stem/progenitor cell phenotype in other tissue types. Using a RT-PCR array, we detected downregulation of multiple genes involved in stem/progenitor cell biology such as OCT4 and LIF as well as cytokines such as VEGFA, BDNF, and CSF2 in cells with Wnt10B knockdown.

CONCLUSIONS

These findings show that genes upregulated in prostate cancer-reactive stroma promote progression when expressed in prostate stromal cells. Moreover, these data indicate that the DRS model recapitulates key aspects of cancer cell/reactive stroma interactions in prostate cancer.

Tumour-microenvironment interactions: role of tumour stroma and proteins produced by cancer-associated fibroblasts in chemotherapy response

BACKGROUND

Cytotoxic chemotherapy improves survival for some, but not all, cancer patients. Non-responders may experience unnecessary toxicity and cancer progression, thus creating an urgent need for biomarkers that can predict the response to chemotherapy. So far, the search for such biomarkers has primarily been focused on the cancer cells and less on their surrounding stroma. This stroma is known to act as a key regulator of tumour progression and, in addition, has been associated with drug delivery and drug efficacy. Fibroblasts represent the major cell type in cancer-associated stroma and they secrete extracellular matrix proteins as well as growth factors. This Medline-based literature review summarises the results from studies on epithelial cancers and aimed at investigating relationships between the quantity and quality of the intra-tumoral stroma, the cancer-associated fibroblasts, the proteins they produce and the concomitant response to chemotherapy. Biomarkers were selected for review that are known to affect cancer-related characteristics and patient prognosis.

RESULTS

The current literature supports the hypothesis that biomarkers derived from the tumour stroma may be useful to predict response to chemotherapy. This notion appears to be related to the overall quantity and cellularity of the intra-tumoural stroma and the predominant constituents of the extracellular matrix.

CONCLUSION

Increasing evidence is emerging showing that tumour-stroma interactions may not only affect tumour progression and patient prognosis, but also the response to chemotherapy. The tumour stroma-derived biomarkers that appear to be most appropriate to determine the patient's response to chemotherapy vary by tumour origin and the availability of pre-treatment tissue. For patients scheduled for adjuvant chemotherapy, the most promising biomarker appears to be the PLAU: SERPINE complex, whereas for patients scheduled for neo-adjuvant chemotherapy the tumour stroma quantity appears to be most relevant.

Epidermal growth factor promotes protein degradation of epithelial protein lost in neoplasm (EPLIN), a putative metastasis suppressor, during epithelial-mesenchymal transition

Aberrant expression of EGF receptors has been associated with hormone-refractory and metastatic prostate cancer (PCa). However, the molecular mechanism for EGF signaling in promoting PCa metastasis remains elusive. Using experimental models of PCa metastasis, we demonstrated that EGF could induce robust epithelial-mesenchymal transition (EMT) and increase invasiveness. Interestingly, EGF was found to be capable of promoting protein turnover of epithelial protein lost in neoplasm (EPLIN), a putative suppressor of EMT and tumor metastasis. Mechanistic study revealed that EGF could activate the phosphorylation, ubiquitination, and degradation of EPLIN through an extracellular signal-regulated kinase 1/2 (ERK1/2)-dependent signaling cascade. Pharmacological inhibition of the ERK1/2 pathway effectively antagonized EGF-induced EPLIN degradation. Two serine residues, i.e. serine 362 and serine 604, were identified as putative ERK1/2 phosphorylation sites in human EPLIN, whose point mutation rendered resistance to EGF-induced protein turnover. This study elucidated a novel molecular mechanism for EGF regulation of EMT and invasiveness in PCa cells, indicating that blockade of EGF signaling could be beneficial in preventing and retarding PCa metastasis at early stages.

Biomarker identification with ligand-targeted nucleoprotein assemblies

AIMS

Since many biomarkers of both the tumor and its microenvironment are expected to involve differential expression of divalent proteins capable of protein or peptide ligand interaction, we are developing multivalent nanodevices for the identification of biomarkers in prostate cancer.

PATIENTS & METHODS

We compared a multivalent thioredoxin-targeted nanodevice with monovalent thioredoxin in binding to human prostate cell line(s) and freshly frozen tissue specimens obtained after resection from patients with biopsy-proven prostate cancer.

CONCLUSION

The nanodevice binds specifically with enhanced avidity to tumor microenvironment-associated stromal cells in prostate cancer tissue specimens. Cells that bind the nanodevice also reacted with antibodies to dimeric thioredoxin reductases 1 and 2, suggesting the utility of the nanodevice as a potentially specific and functional marker of tumor stromal cells.

Determining prostate cancer-specific death through quantification of stromogenic carcinoma area in prostatectomy specimens

We previously reported that reactive stroma grading in prostate cancer (PCa) is predictive of biochemical recurrence in prostatectomies and biopsies. In this study, we tested whether quantifying the percentage of reactive stromal grade 3 (RSG 3; stromogenic carcinoma pattern) in the entire tumor is predictive of PCa-specific death. Whole-mount prostatectomies operated by a single surgeon obtained between 1983 and 1998 were reviewed. Reactive stroma was evaluated as described previously, and areas of RSG 3 in the entire tumor were registered as percentages of total tumor. Statistical analysis was performed using Spearman, Kaplan-Meier, and Cox analyses. In all, 872 cases were evaluable. Quantification of RSG 3 percentage was an independent predictor of biochemical recurrence, analyzed as a continuous or grouped variable. Patients with higher RSG 3 percentages (larger tumor areas with RSG 3) had a significantly decreased biochemical recurrence-free survival than those with a lower RSG 3 percentage, even within the Gleason score 7 subset of patients. A nomogram introduced this new variable to the model. Furthermore, quantification of RSG 3 percentage was significantly predictive of PCa-specific death. Quantification of the RSG 3 (stromogenic carcinoma) area in PCa provides additional novel information on prognosis. These data substantiate the concept that the tumor microenvironment holds significant predictive information, as well as biological significance.

Tumor indicating normal tissue could be a new source of diagnostic and prognostic markers for prostate cancer

IMPORTANCE OF THE FIELD

Prostate cancer is a common and multifocal disease but the diagnostic methods available are unsatisfactory. Most tumors present are of low malignant potential, whereas others are highly aggressive. At present, imaging cannot be used to guide tissue biopsies safely towards the most aggressive tumor present. To handle this problem multiple needle biopsies are taken. The biopsies often contain only normal prostate tissue, and even if the tumor is sampled it is not known whether a more aggressive cancer is present elsewhere in the organ. If changes in the normal tissue indicate the presence and nature of tumors, this information could be used to improve diagnostics and prognostics of prostate cancer.

AREAS COVERED IN THIS REVIEW

Current evidence that the tumor-adjacent morphologically normal prostate tissue is not completely normal is reviewed, and that this tissue, named tumor indicating normal tissue (TINT) by the authors, can be used to diagnose prostate cancer.

WHAT THE READER WILL GAIN

The reader will understand that tumors need to affect their surroundings in order to grow and metastasize and that the normal prostate tissue is therefore tinted by the presence and nature of cancer and that this knowledge can be used to develop new diagnostic and prognostic markers.

TAKE HOME MESSAGE

TINT changes could probably, when more rigorously defined and validated, be used to diagnose and prognosticate prostate cancer.

Breast and prostate cancer: more similar than different

Breast cancer and prostate cancer are the two most common invasive cancers in women and men, respectively. Although these cancers arise in organs that are different in terms of anatomy and physiological function both organs require gonadal steroids for their development, and tumours that arise from them are typically hormone-dependent and have remarkable underlying biological similarities. Many of the recent advances in understanding the pathophysiology of breast and prostate cancers have paved the way for new treatment strategies. In this Opinion article we discuss some key issues common to breast and prostate cancer and how new insights into these cancers could improve patient outcomes.

The Sonic Hedgehog pathway stimulates prostate tumor growth by paracrine signaling and recapitulates embryonic gene expression in tumor myofibroblasts

The Hedgehog (Hh) pathway contributes to prostate cancer growth and progression. The presence of robust Sonic Hedgehog (Shh) expression in both normal prostate and localized cancer challenged us to explain the unique growth-promoting effect in cancer. We show here that paracrine Hh signaling exerts a non-cell autonomous effect on xenograft tumor growth and that Hh pathway activation in myofibroblasts alone is sufficient to stimulate tumor growth. Nine genes regulated by Hh in the mesenchyme of the developing prostate were found to be regulated in the stroma of Hh overexpressing xenograft tumors. Correlation analysis of gene expression in matched specimens of benign and malignant human prostate tissue revealed a partial five-gene fingerprint of Hh-regulated expression in stroma of all cancers and the complete nine-gene fingerprint in the subset of tumors exhibiting a reactive stroma. No expression fingerprint was observed in benign tissues. We conclude that changes in the prostate stroma due to association with cancer result in an altered transcriptional response to Hh that mimics the growth-promoting actions of the fetal mesenchyme. Patients with an abundance of myofibroblasts in biopsy tissue may comprise a subgroup that will exhibit a particularly good response to anti-Hh therapy.

Global gene expression analysis of reactive stroma in prostate cancer

PURPOSE

Marked reactive stroma formation, designated as grade 3 reactive stroma, is associated with poor outcome in clinically localized prostate cancer. To understand the biological processes and signaling mechanisms underlying the formation of such reactive stroma, we carried out microarray gene expression analysis of laser-captured reactive stroma and matched normal stroma.

EXPERIMENTAL DESIGN

Seventeen cases of reactive stroma grade 3 cancer were used to laser-capture tumor and normal stroma. Expression analysis was carried out using Agilent 44K arrays. Up-regulation of selected genes was confirmed by quantitative reverse transcription-PCR. Expression data was analyzed to identify significantly up- and down-regulated genes, and gene ontology analysis was used to define pathways altered in reactive stroma.

RESULTS

A total of 544 unique genes were significantly higher in the reactive stroma and 606 unique genes were lower. Gene ontology analysis revealed significant alterations in a number of novel processes in prostate cancer reactive stroma, including neurogenesis, axonogenesis, and the DNA damage/repair pathways, as well as evidence of increases in stem cells in prostate cancer reactive stroma.

CONCLUSIONS

Formation of reactive stroma in prostate cancer is a dynamic process characterized by significant alterations in growth factor and signal transduction pathways and formation of new structures, including nerves and axons.

Low stroma androgen receptor level in normal and tumor prostate tissue is related to poor outcome in prostate cancer patients

BACKGROUND

The role of androgen receptors (ARs) in the prostate tumor cell environment is largely unknown.

METHODS

AR immunostaining was evaluated in relation to stroma morphology, expression of AR co-activator ARA55, tumor characteristics and clinical outcome in normal and prostate cancer (PCa) tissue obtained at transurethral resection in men treated with expectancy, and in diagnostic transrectal core biopsies in men treated with surgical castration. Stroma composition was studied by Masson-trichrome and desmin staining. Levels of AR and ARA55 mRNA were quantified by laser micro-dissection and RT-PCR.

RESULTS

The percentage of cells with positive nuclear AR immunostaining in the tumor and normal stroma was inversely related to Gleason score, tumor size, tumor stage, metastasis, response to castration therapy, and cancer-specific survival. The AR staining in the normal stroma provided independent prognostic information in Cox multiple linear regression analysis. Loss of stroma AR staining was linked to low expression of ARA55 in stroma smooth muscle cells, and in tumors also to gradual disappearance of this cell type.

CONCLUSIONS

PCa aggressiveness and efficacy of castration therapy are related to AR levels in the tumor stroma and importantly to AR levels in the surrounding normal prostate tissue stroma. .