Transforming growth factor beta 1 as a biomarker for prostate cancer

TGF Beta1 Expression Correlates with Survival and Tumor Aggressiveness of Prostate Cancer

BACKGROUND

Although biopsy Gleason score and clinical stage can be used to inform treatment decisions for prostate cancer, identifying molecular markers of tumor aggressiveness could lead to a more tailored approaches to therapy. In the present study, we investigated the association of transforming growth factor (TGF)-β1 levels and various markers of tumor aggressiveness and explore some potential mechanisms underlying the associations.

METHODS

We used human and murine prostate cancer cell lines and their respective hormone resistance sub-lines, in vitro and in vivo to examine the changes in tumor aggressiveness, as well as the pathway responsible for these changes. Furthermore, 105 prostate cancer biopsy specimens were analyzed to correlate the level of TGF-β1 with the clinical characteristics of patients.

RESULTS

Our data revealed that activated TGF-β1 signaling resulted in more aggressive tumor growth and augmented the epithelial-mesenchymal transition. Activated IL-6 signaling was associated with TGF-β1 levels and the aggressive tumor features noted in TGF-β1-positive prostate cancers in vitro and in vivo. Furthermore, the TGF-β1 levels significantly correlated with Tregs accumulation in vivo. The clinical data indicated that TGF-β1 immunoreactivity had a moderate positive correlation with IL-6 staining, advanced clinical stage, higher Gleason score, and pretreatment PSA in patients with prostate cancer.

CONCLUSIONS

TGF-β1 levels are significantly associated with aggressive prostate features. In vitro and in vivo alternations of TGF-β1 expression impacts tumor invasiveness, tumor growth rate and recruitment of immunosuppressive Treg cells in the tumor microenvironment. TGF-β1 expression may represent a clinical useful biomarker to guide prostate cancer treatment decisions.

CIN85 modulates TGFβ signaling by promoting the presentation of TGFβ receptors on the cell surface

Members of the transforming growth factor β (TGFβ) family initiate cellular responses by binding to TGFβ receptor type II (TβRII) and type I (TβRI) serine/threonine kinases, whereby Smad2 and Smad3 are phosphorylated and activated, promoting their association with Smad4. We report here that TβRI interacts with the SH3 domains of the adaptor protein CIN85 in response to TGFβ stimulation in a TRAF6-dependent manner. Small interfering RNA-mediated knockdown of CIN85 resulted in accumulation of TβRI in intracellular compartments and diminished TGFβ-stimulated Smad2 phosphorylation. Overexpression of CIN85 instead increased the amount of TβRI at the cell surface. This effect was inhibited by a dominant-negative mutant of Rab11, suggesting that CIN85 promoted recycling of TGFβ receptors. CIN85 enhanced TGFβ-stimulated Smad2 phosphorylation, transcriptional responses, and cell migration. CIN85 expression correlated with the degree of malignancy of prostate cancers. Collectively, our results reveal that CIN85 promotes recycling of TGFβ receptors and thereby positively regulates TGFβ signaling.

Identification of plasma protein profiles associated with risk groups of prostate cancer patients

PURPOSE

Early detection of prostate cancer (PC) using prostate-specific antigen (PSA) in blood reduces PC-death among unscreened men. However, due to modest specificity of PSA at commonly used cut-offs, there are urgent needs for additional biomarkers contributing enhanced risk classification among men with modestly elevated PSA.

EXPERIMENTAL DESIGN

Recombinant antibody microarrays were applied for protein expression profiling of 80 plasma samples from routine PSA-measurements, a priori divided into four risk groups, based on levels of total and %free PSA.

RESULTS

The results demonstrated that plasma protein profiles could be identified that pin-pointed PC (a malignant biomarker signature) and most importantly that showed moderate to high correlation with biochemically defined PC risk groups. Notably, the data also implied that the risk group with midrange PSA and low %free PSA, a priori known to be heterogeneous, could be further stratified into two subgroups, more resembling the lowest and highest risk groups, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

In this pilot study, we have shown that plasma protein biomarker signatures, associated with risk groups of PC, could be identified from crude plasma samples using affinity proteomics. This approach could in the longer perspective provide novel opportunities for improved risk classification of PC patients.

Novel tools for prostate cancer prognosis, diagnosis, and follow-up

Prostate-specific antigen (PSA) is the main diagnostic tool when it comes to prostate cancer but it possesses serious limitations. Therefore, there is an urgent need for more sensitive and specific biomarkers for prostate cancer prognosis and patient follow-up. Recent advances led to the discovery of many novel diagnostic/prognostic techniques and provided us with many worthwhile candidates. This paper briefly reviews the most promising biomarkers with respect to their implementation in screening, early detection, diagnostic confirmation, prognosis, and prediction of therapeutic response or monitoring disease and recurrence; and their use as possible therapeutic targets. This review also examines the possible future directions in the field of prostate cancer marker research.

TGF-β cascade regulation by PPP1 and its interactors -impact on prostate cancer development and therapy

Protein phosphorylation is a key mechanism by which normal and cancer cells regulate their main transduction pathways. Protein kinases and phosphatases are precisely orchestrated to achieve the (de)phosphorylation of candidate proteins. Indeed, cellular health is dependent on the fine-tune of phosphorylation systems, which when deregulated lead to cancer. Transforming growth factor beta (TGF-β) pathway involvement in the genesis of prostate cancer has long been established. Many of its members were shown to be hypo- or hyperphosphorylated during the process of malignancy. A major phosphatase that is responsible for the vast majority of the serine/threonine dephosphorylation is the phosphoprotein phosphatase 1 (PPP1). PPP1 has been associated with the dephosphorylation of several proteins involved in the TGF-β cascade. This review will discuss the role of PPP1 in the regulation of several TGF-β signalling members and how the subversion of this pathway is related to prostate cancer development. Furthermore, current challenges on the protein phosphatases field as new targets to cancer therapy will be addressed.

Transforming growth factor-beta signaling promotes hepatocarcinogenesis induced by p53 loss

Hepatocellular carcinoma (HCC) results from the accumulation of deregulated tumor suppressor genes and/or oncogenes in hepatocytes. Inactivation of TP53 and inhibition of transforming growth factor-beta (TGF-β) signaling are among the most common molecular events in human liver cancers. Thus, we assessed whether inactivation of TGF-β signaling, by deletion of the TGF-β receptor, type II (Tgfbr2), cooperates with Trp53 loss to drive HCC formation. Albumin-cre transgenic mice were crossed with floxed Trp53 and/or floxed Tgfbr2 mice to generate mice lacking p53 and/or Tgfbr2 in the liver. Deletion of Trp53 alone (Trp53(KO) ) resulted in liver tumors in approximately 41% of mice by 10 months of age, whereas inactivation of Tgfbr2 alone (Tgfbr2(KO) ) did not induce liver tumors. Surprisingly, deletion of Tgfbr2 in the setting of p53 loss (Trp53(KO) ;Tgfbr2(KO) ) decreased the frequency of mice with liver tumors to around 17% and delayed the age of tumor onset. Interestingly, Trp53(KO) and Trp53(KO) ;Tgfbr2(KO) mice develop both HCC and cholangiocarcinomas, suggesting that loss of p53, independent of TGF-β, may affect liver tumor formation through effects on a common liver stem cell population. Assessment of potential mechanisms through which TGF-β signaling may promote liver tumor formation in the setting of p53 loss revealed a subset of Trp53(KO) tumors that express increased levels of alpha-fetoprotein. Furthermore, tumors from Trp53(KO) mice express increased TGF-β1 levels compared with tumors from Trp53(KO) ;Tgfbr2(KO) mice. Increased phosphorylated Smad3 and ERK1/2 expression was also detected in the tumors from Trp53(KO) mice and correlated with increased expression of the TGF-β responsive genes, Pai1 and Ctgf.

CONCLUSION

TGF-β signaling paradoxically promotes the formation of liver tumors that arise in the setting of p53 inactivation.

Transforming growth factor-beta signaling promotes hepatocarcinogenesis induced by p53 loss

Hepatocellular carcinoma (HCC) results from the accumulation of deregulated tumor suppressor genes and/or oncogenes in hepatocytes. Inactivation of TP53 and inhibition of transforming growth factor-beta (TGF-β) signaling are among the most common molecular events in human liver cancers. Thus, we assessed whether inactivation of TGF-β signaling, by deletion of the TGF-β receptor, type II (Tgfbr2), cooperates with Trp53 loss to drive HCC formation. Albumin-cre transgenic mice were crossed with floxed Trp53 and/or floxed Tgfbr2 mice to generate mice lacking p53 and/or Tgfbr2 in the liver. Deletion of Trp53 alone (Trp53(KO) ) resulted in liver tumors in approximately 41% of mice by 10 months of age, whereas inactivation of Tgfbr2 alone (Tgfbr2(KO) ) did not induce liver tumors. Surprisingly, deletion of Tgfbr2 in the setting of p53 loss (Trp53(KO) ;Tgfbr2(KO) ) decreased the frequency of mice with liver tumors to around 17% and delayed the age of tumor onset. Interestingly, Trp53(KO) and Trp53(KO) ;Tgfbr2(KO) mice develop both HCC and cholangiocarcinomas, suggesting that loss of p53, independent of TGF-β, may affect liver tumor formation through effects on a common liver stem cell population. Assessment of potential mechanisms through which TGF-β signaling may promote liver tumor formation in the setting of p53 loss revealed a subset of Trp53(KO) tumors that express increased levels of alpha-fetoprotein. Furthermore, tumors from Trp53(KO) mice express increased TGF-β1 levels compared with tumors from Trp53(KO) ;Tgfbr2(KO) mice. Increased phosphorylated Smad3 and ERK1/2 expression was also detected in the tumors from Trp53(KO) mice and correlated with increased expression of the TGF-β responsive genes, Pai1 and Ctgf.

CONCLUSION

TGF-β signaling paradoxically promotes the formation of liver tumors that arise in the setting of p53 inactivation.

The additional value of TGFβ1 and IL-7 to predict the course of prostate cancer progression

Background

Given the fact that prostate cancer incidence will increase in the coming years, new prognostic biomarkers are needed with regard to the biological aggressiveness of the prostate cancer diagnosed. Since cytokines have been associated with the biology of cancer and its prognosis, we determined whether transforming growth factor beta 1 (TGFβ1), interleukin-7 (IL-7) receptor and IL-7 levels add additional prognostic information with regard to prostate cancer-specific survival.

Materials and methods

Retrospective survival analysis of forty-four prostate cancer patients, that underwent radical prostatectomy, was performed (1989–2001). Age, Gleason score and pre-treatment PSA levels were collected. IL-7, IL-7 receptor and TGFβ1 levels in prostate cancer tissue were determined by quantitative real-time RT-PCR and their additional prognostic value analyzed with regard to prostate cancer survival. Hazard ratios and their confidence intervals were estimated, and Akaike’s information criterion was calculated for model comparison.

Results

The predictive ability of a model for prostate cancer survival more than doubled when TGFβ1 and IL-7 were added to a model containing only the Gleason score and pre-treatment PSA (AIC: 18.1 and AIC: 6.5, respectively).

Conclusion

IL-7 and TGFβ1 are promising markers to indicate those at risk for poor prostate cancer survival. This additional information may be of interest with regard to the biological aggressiveness of the diagnosed prostate cancer, especially for those patients screened for prostate cancer and their considered therapy.

Spotlight on differentially expressed genes in urinary bladder cancer

INTRODUCTION

We previously identified common differentially expressed (DE) genes in bladder cancer (BC). In the present study we analyzed in depth, the expression of several groups of these DE genes.

MATERIALS AND METHODS

Samples from 30 human BCs and their adjacent normal tissues were analyzed by whole genome cDNA microarrays, qRT-PCR and Western blotting. Our attention was focused on cell-cycle control and DNA damage repair genes, genes related to apoptosis, signal transduction, angiogenesis, as well as cellular proliferation, invasion and metastasis. Four publicly available GEO Datasets were further analyzed, and the expression data of the genes of interest (GOIs) were compared to those of the present study. The relationship among the GOI was also investigated. GO and KEGG molecular pathway analysis was performed to identify possible enrichment of genes with specific biological themes.

RESULTS

Unsupervised cluster analysis of DNA microarray data revealed a clear distinction in BC vs. control samples and low vs. high grade tumors. Genes with at least 2-fold differential expression in BC vs. controls, as well as in non-muscle invasive vs. muscle invasive tumors and in low vs. high grade tumors, were identified and ranked. Specific attention was paid to the changes in osteopontin (OPN, SPP1) expression, due to its multiple biological functions. Similarly, genes exhibiting equal or low expression in BC vs. the controls were scored. Significant pair-wise correlations in gene expression were scored. GO analysis revealed the multi-facet character of the GOIs, since they participate in a variety of mechanisms, including cell proliferation, cell death, metabolism, cell shape, and cytoskeletal re-organization. KEGG analysis revealed that the most significant pathway was that of Bladder Cancer (p = 1.5×10(-31)).

CONCLUSIONS

The present work adds to the current knowledge on molecular signature identification of BC. Such works should progress in order to gain more insight into disease molecular mechanisms.

Action, localization and structure-function relationship of growth factors and their receptors in the prostate

Whereas the direct action of sex steroids, namely of androgens, on prostate cell division was questioned as early as in the 1970s, and remains so, the interest in prostatic growth factors (GFs) is rather recent but has expanded tremendously in the last five years. This lag period can be partly explained by the fact that, at the time, androgen receptors had just been discovered, and newly developed hormonal regimens or strategies to treat patients with prostate carcinoma (PCa) or epithelioma had generated great enthusiasm and hopes in the medical and scientific community. Another point to consider was the difficulty in maintaining prostate tissues in organ cultures and the relative novelty of culturing prostate epithelial cells in monolayers. Failures of sex steroids to elicit a direct positive response on prostate cell divisionin vitro, as seenin vivo, were interpreted as resulting from inappropriate models or culture conditions. However, the increasing number of reports confirming the lack of mitogenic activity of sex steroidsin vitro, coupled with the powerful mitogenic activity of GFs displayed in other systems, the discovery of GF receptors (GF-Rs), and the elucidation of their signalling pathways showing sex steroid receptors as potential substrates of GF-activated protein kinases gradually led to an increased interest in the putative role of GFs in prostate physiopathology. Of utmost importance was the recognition that hormone refractiveness was responsible for PCa progression, and for the poor outcome of patients with advanced disease under endocrine therapies. This problem remains a major issue and it raises several key questions that need to be solved at the fundamental and clinical levels.

Murine CTLL-2 cells respond to mIL12: prospects for developing an alternative bioassay for measurement of murine cytokines IL12 and IL18

Cell line-based bioassays are becoming increasingly popular for assessment of biological activities of cytokines primarily because these are easy to perform and are not subject to donor variation. A well characterised cell line with world wide availability would further minimise the inter-assay variations. C57BL/6 mice derived T cell line; CTLL-2 fits this criterion. We explored the potential of CTLL-2 cells to develop a bioassay to detection of murine (m) IL12 and mIL18. Both cytokines have shown significant activity against a number of cancers and importantly, act synergistically via mutual upregulation of each other's receptors. The preliminary flow cytometric analyses of immunostained CTLL-2 cells showed that approximately 65% expressed mIL12 and approximately 5% expressed mIL18 receptors suggesting that these may respond to mIL12. As predicted, cells incubated with different doses of mIL12 or mIL18 for 72 h were responsive to mIL12 and not to mIL18. However, when pre-treated with mIL12 for 24 h prior to incubation with mIL18, there was a significant enhancement in response. The sensitivity of the response was comparable to that obtained using the conventional splenocyte-based IFNgamma release assay. The cytokine specificity of the response was proven unequivocally when significant reduction in CTLL-2 response was observed in the presence of the relevant neutralising antibodies. Finally, we could successfully detect lowest doses of approximately 0.1 pg/microL mIL12 or 40 pg/mL of mIL18 in cell supernatants in a cytokine specific manner, which is lower than the resting levels of these cytokines in mouse sera. Again the sensitivity was comparable to that observed in the conventional IFNgamma release assay. Hence, we have demonstrated the potential of CTLL-2-based bioassay to detect biologically active mIL12 and mIL18 in biological samples accurately and reproducibly.

Molecular markers of prostate cancer

Although prostate-specific antigen (PSA) has evolved as a very useful tool for detection of prostate cancer, there remains an urgent need for more accurate biomarkers to diagnose prostate cancer and predict cancer-related outcomes. Recent advances in the study of proteomics and high throughput techniques have led to the discovery of many potential biomarkers for prostate cancer. This article briefly reviews the current status of PSA testing and discusses several candidate protein biomarkers for prostate cancer, as well as highlighting some recent proteomic discoveries with the potential to supplement or even replace PSA for the diagnosis and prognosis of prostate cancer.

Tissue expression of transforming growth factor-beta1 and its receptors: correlation with pathologic features and biochemical progression in patients undergoing radical prostatectomy

OBJECTIVES

To determine whether the abnormal expression of transforming growth factor-beta1 (TGF-beta1) and/or its receptors (TGFbeta-RI and TGFbeta-RII) is associated with prostate cancer features and progression; and to investigate the relationship between tissue expression of TGFs and blood levels of TGF-beta1.

METHODS

Immunohistochemical staining for TGF-beta1, TGFbeta-RI, and TGFbeta-RII was carried out on archival specimens from 118 consecutive patients who underwent radical prostatectomy for clinically localized disease (median follow-up 57.5 months). Preoperative plasma TGF-beta1 levels were also measured.

RESULTS

TGF-beta1 was overexpressed in 71 (60%) of 118 patients, and TGFbeta-RI and TGFbeta-RII expression was decreased in 34 (29%) and 39 (33%) of 118 patients, respectively. Of the 118 patients, 82 (70%) had abnormal expression of at least one of the three TGFs and 22 (19%) had abnormal expression of all three. The concordance rates between the expression of TGF-beta1 and its receptors were 54% and 62%. Abnormal expression of all three TGFs was significantly associated with extracapsular disease. However, only decreased expression of TGFbeta-RI and TGFbeta-RII was significantly associated with seminal vesicle involvement and greater pathologic Gleason score. Preoperative plasma TGF-beta1 levels were significantly elevated in patients with abnormal expression of TGFs. TGFbeta-RI expression and surgical margin status were independently associated with biochemical progression.

CONCLUSIONS

Our results showed that abnormal expression of TGF-beta1 and its receptors is common in prostate cancer. TGF-beta1 overexpression is moderately but significantly associated with a loss of expression of TGFbeta-RI and TGFbeta-RII. Loss of TGFbeta-RI expression is a prognostic marker in patients with prostate cancer.

Immunopathological prognostic and predictive factors in prostate cancer

Prostate cancer is the leading male malignancy in the Western world. Patients with prostate cancer have an unpredictable clinical course, as three biologically different types of tumor exist. This review summarises some of the recent progress made in understanding the biology of prostate cancer with special reference to the prognostic and predictive role of immunohistochemical markers. The prognostic value of established prognostic variables is also discussed.

Neuroepithelial interactions in prostate cancer are enhanced in the presence ofprostatic stroma

OBJECTIVES

To develop an in vitro model that tests the involvement of prostatic stroma in the active reciprocal interactions between malignant epithelial cells and nerves that occur in perineural invasion.

METHODS

Each of three metastatic prostate cancer cell lines (LnCaP, PC3, and DU-145 at 10(3)) was co-cultured in sextuplet experiments with a human prostate stromal cell line (HTS-40C at 10(3)) and a mouse dorsal root ganglion in matrigel for 13 days. Carcinoma/ganglia co-cultures (10(6) cells) in the absence of stroma served as controls. Areas of carcinoma cell growth (day 1), neurite growth (days 1 and 3), and perineural invasion (neuroepithelial halo area, day 11) were quantified.

RESULTS

Mean neurite outgrowth was enhanced in the presence of stroma with LnCaP and PC3, but not with DU-145. Perineural invasion and carcinoma cell growth were enhanced in the presence of stroma in experiments with all three cell lines. The mean cell area (in square millimeters) increased 54.7% with LnCaP in the presence of stroma (P <0.001). PC3 and DU-145 growth was enhanced 88.5% and 43.4%, respectively, in the presence of stroma. The mean neurite growth (in millimeters) on days 1 and 3 increased 50.8% and 70.8% with LnCaP in the presence of stroma. This enhancement was observed with PC3 by 88.1% and 64.5%. The mean neurite growth decreased in the presence of stroma with DU-145 by 4.9% and 5.4%. Perineural invasion increased 33.8% in the presence of stroma with LnCaP and 24.3% and 26.1% with PC3 and DU-145, respectively.

CONCLUSIONS

These novel findings strongly suggest active stromal participation in perineural invasion. The identification of specific stromal factors may suggest ways of preventing the progression of prostate cancer.

Bcl-2 antagonizes the combined apoptotic effect of transforming growth factor-beta and dihydrotestosterone in prostate cancer cells

BACKGROUND

We previously demonstrated that dihydrotestosterone (DHT) enhances transforming growth factor-beta (TGF-beta) -induced apoptosis in human prostate cancer cells (Endocrinology 2001;142:2419-2426).

METHODS

In this study, the ability of the apoptosis suppressor bcl-2 to directly antagonize the combined apoptotic effect of TGF-beta and DHT in the androgen-sensitive LNCaP TbetaRII prostate cancer cells was examined. The previously cloned TGF-RbetaII receptor LNCaP cells, responsive to both TGF-beta and androgens, were engineered to overexpress the bcl-2 oncoprotein and the profile of apoptosis induction was analyzed in response to TGF-beta alone (5.0 ng/ml) or in combination with DHT (1 nM).

RESULTS

Biological characterization of cloned LNCaP TbetaRII hygromycin/bcl-2 transfectants demonstrated that bcl-2 overexpression resulted in a significant inhibition of the combined TGF-beta and DHT apoptotic effect in prostate cancer cells (P < 0.01). Furthermore, molecular analysis indicated that this antagonistic effect of bcl-2 on apoptosis was due to partial suppression of TGF-beta and DHT-mediated induction of caspase-1 expression and activation in LNCaP TbetaRII-hygro/bcl-2 transfectants. These results support a potential bcl-2 interference with the TGF-beta and androgen apoptotic signaling in prostate cancer cells by means of an antagonistic effect on caspase-1 activation.

CONCLUSION

This evidence may have mechanistic significance in understanding the contribution of bcl-2 overexpression in the development of androgen-independent prostate cancer by means of conferring resistance to TGF-beta-mediated apoptosis.

Dihydrotestosterone enhances transforming growth factor-beta-induced apoptosis in hormone-sensitive prostate cancer cells

In this study, the potential interactions between dihydrotestosterone (DHT), a survival factor, and transforming growth factor-beta (TGF-beta), an apoptotic inducer, were examined in a derivative of the hormone-sensitive prostate cancer cell line LNCAP: The LNCaP TGF-beta receptor II cells, engineered to express TGF-beta receptor II, are sensitive to both DHT and TGF-beta. Surprisingly, when the LNCaP TGF-beta receptor II cells were treated with TGF-beta in the presence of physiological levels of DHT, both cell cycle arrest and apoptosis induction were significantly enhanced over TGF-beta alone. This effect temporally correlated with an increased expression of the cell cycle regulator p21 as well as the apoptotic executioner, procaspase-1, and a parallel down-regulation of the antiapoptotic protein, bcl-2. Expression of bax and caspase-3 proteins remained unchanged following treatment. Furthermore, apoptosis induction was suppressed by the caspase-1 inhibitor, z-YVAD, but not the caspase-3 inhibitor, z-DQMD, thus demonstrating the functional significance of increased procaspase-1 expression in TGF-beta-mediated apoptosis in prostate cancer cells. These results indicate that TGF-beta-mediated apoptosis can actually be enhanced by androgens through specific mechanisms involving cell cycle and apoptosis regulators and provide initial evidence on the ability of physiological levels of androgens to stimulate the intrinsic apoptotic potential of prostate cancer cells. Therefore, this study provides a molecular basis for the priming of prostate cancer cells for maximal apoptosis induction, during hormone- ablation therapy.

Preoperative plasma levels of transforming growth factor beta(1) (TGF-beta(1)) strongly predict progression in patients undergoing radical prostatectomy

PURPOSE

Elevated local and circulating levels of transforming growth factor beta(1) (TGF-beta(1)) have been associated with prostate cancer invasion and metastasis. We tested the hypothesis that preoperative plasma TGF-beta(1) levels would independently predict cancer stage and prognosis in patients who undergo radical prostatectomy.

PATIENTS AND METHODS

The study group consisted of 120 consecutive patients who underwent radical prostatectomy for clinically localized prostate cancer (median follow-up, 53.8 months). Preoperative plasma levels of TGF-beta(1) were measured and correlated with pathologic parameters and clinical outcomes. TGF-beta(1) levels also were measured in 44 healthy men without cancer, in 19 men with prostate cancer metastatic to regional lymph nodes, and in 10 men with prostate cancer metastatic to bone.

RESULTS

Plasma TGF-beta(1) levels in patients with lymph node metastases (14.2 +/- 2.6 ng/mL) and bone metastases (15.5 +/- 2.4 ng/mL) were higher than those in radical prostatectomy patients (5.2 +/- 1.3 ng/mL) and healthy subjects (4.5 +/- 1.2 ng/mL) (P <.001). In a preoperative analysis, preoperative plasma TGF-beta(1) level and biopsy Gleason sum both were predictors of organ-confined disease (P =.006 and P =.006, respectively) and PSA progression (P <.001 and P =.021, respectively). In a postoperative multivariate analysis, preoperative plasma TGF-beta(1) level, pathologic Gleason sum, and surgical margin status were predictors of PSA progression (P =.020,P =.020, and P =.022, respectively). In patients who progressed, preoperative plasma TGF-beta(1) levels were higher in those with presumed distant compared with local-only failure (P =.019).

CONCLUSION

Plasma TGF-beta(1) levels are markedly elevated in men with prostate cancer metastatic to regional lymph nodes and bone. In men without clinical or pathologic evidence of metastases, the preoperative plasma TGF-beta(1) level is a strong predictor of biochemical progression after surgery, presumably because of an association with occult metastatic disease present at the time of radical prostatectomy.

Role of transforming growth factor-beta1 in prostate cancer

TGF-beta1 is an important regulator of the normal and malignant prostate. In the non-malignant prostate, TGF-beta1 stimulates cell differentiation, inhibits epithelial cell proliferation, and induces epithelial cell death. TGF-beta1 is secreted into semen where it is an important immunosuppressive factor. Prostate cancer cells express high levels of TGF-beta1, which seems to enhance prostate cancer growth and metastasis by stimulating angiogenesis and by inhibiting immune responses directed against tumour cells. Prostate cancer cells frequently lose their TGF-beta receptors and acquire resistance to the anti-proliferative and pro-apoptotic effects of TGF-beta1. Accordingly, high expression of TGF-beta1 and loss of TGF-beta receptor expression have been associated with a particularly bad prognosis in human prostate cancer patients. TGF-beta1 also seems to be a mediator of castration-induced apoptosis in androgen dependent normal and malignant prostate epithelial cells. The ability of some prostate tumours to avoid castration-induced apoptosis may not, however, be simply due to loss of TGF-beta receptor type I or type II expression in the tumour cells. It may also be related to an inability of these cells to up-regulate TGF-beta receptor levels in response to castration or possibly due to defects downstream of the receptors. Short-term therapy-induced changes in the TGF-beta system in prostate tumours can probably be used to predict the long-term response to androgen ablation treatment. Further investigations into the TGF-beta system in the prostate are needed, however, to elucidate how alterations in this system affect the behaviour of prostate tumours, and whether this system can be manipulated for therapeutical purposes.

Transforming growth factor-beta is an autocrine mitogen for a novel androgen-responsive murine prostatic smooth muscle cell line, PSMC1

A prostatic smooth muscle cell line (PSMC1) was established from the dorsolateral prostate of p53 null mice. The cell line is nontumorigenic when inoculated subcutaneously, under the renal capsule or intraprostatically in syngeneic mice. These cells express alpha-smooth muscle actin (alpha-SMA), indicating their smooth muscle origin, and TGF-beta significantly enhances expression of alpha-SMA. The cells express both androgen receptor (AR) mRNA and protein, and respond mitogenically to physiological concentrations of androgens. PSMC1 cells produce significant amounts of TGF-beta, which stimulates growth by an autocrine mechanism. Dihydrotestosterone (DHT) increases proliferation of PSMC1 cells by promoting TGF-beta secretion. Considering the significant inhibitory effect of TGF-beta on prostatic epithelial cells and its stimulatory effect on the PSMC1 cells, we postulate that TGF-beta produced by prostatic smooth muscle cells may have a paracrine effect on the prostatic epithelium. We also postulate that TGF-beta may be involved in the etiology of benign prostatic hyperplasia (BPH) by stimulating excessive stromal proliferation. Line PSMC1 is the first reported androgen-responsive murine smooth muscle cell line. It will be useful for in vivo and in vitro experiments to study the mechanisms of androgen action on prostatic stroma and for delineating the interactions that occur between prostatic smooth muscle and epithelium that may lead to prostatic diseases such as BPH.

Growth factors and epithelial-stromal interactions in prostate cancer development

Epithelial-stromal interactions are important not only in growth, development, and functional cytodifferentiation of the prostate but also in derangements of prostate gland such as BPH and prostate carcinoma. This chapter explores the roles of epithelium and stroma during this delicate process and highlights the role and mutual influence of each on the other. It also examines the importance of ECM in mediating the effects of androgens and drawn attention to estrogen and genetic factors in the process. During this process of epithelial-stromal interaction, growth factors play a central role in mediating the interactions. This chapter focuses on the role of several growth factors including epidermal growth factor, fibroblast growth factor, transforming growth factor alpha, transforming growth factor beta, insulin-like growth factor-1, vascular endothelial growth factor, nerve growth factor, platelet-derived growth factor, and hepatocyte growth factor. This chapter emphasizes the importance of epithelial-stromal interactions in tumorigenesis and highlights the switch of paracrine to autocrine mode during the process of carcinogenesis.

Analysis of type T1 and T2 cytokines in patients with prostate cancer

BACKGROUND

It has been proposed that a dysregulation in the balance between type T1 (IL-2, IFN-gamma) and type T2 (IL-4, IL-10) cytokines may be implicated in the development of cancer.

METHODS

We determined the expression of IL-2, IL-4, IL-10, and IFN-gamma in CD4 and CD8 lymphocytes by flow cytometry in 12 patients with prostate cancer and in 7 healthy subjects. In addition to the basal expression of these cytokines, their expression was also determined, following stimulation of lymphocytes with PMA (phorbol 12-mystirate 13 acetate) and ionomycin.

RESULTS

The basal expression of cytokines was scarce, while following stimulation this increased markedly. On the other hand, there was a dysregulation in the balance between T1 and T2 lymphocytes in patients with prostate cancer. To this effect, in relation to healthy subjects, we observed an increase in IL-10 expression and a decrease in IL-2 expression.

CONCLUSIONS

The disequilibrium observed in the balance between type T1 and type T2 cytokines may be implicated in the evolution of neoplastic disease.

Mouse prostate reconstitution model system: A series of in vivo and in vitro models for benign and malignant prostatic disease

BACKGROUND

An elucidation of the complex, morphological and molecular changes that underlie benign and malignant prostatic disease will likely lead to improved methods of diagnosis and therapy for those disorders. To identify and understand the interrelation of the phenotypic and genetic changes inherent in these important diseases requires the development and use of in vivo and in vitro models that closely mimic specific aspects of the disease process. Once the suspected molecular underpinnings of prostatic disease are uncovered, in vivo and in vitro models will be required for further testing of the functional significance of specific genetic alterations as they are identified. In addition models of prostatic disease are necessary to evaluate novel therapeutic approaches.

METHODS

The mouse prostate reconstitution (MPR) model system was developed more than a decade ago with these specific needs in mind. Over the years, specific modifications of the MPR model have demonstrated its versatility and applicability for the study of benign and malignant prostatic disease, including metastatic progression.

RESULTS

We discuss various modifications of the MPR model system made for its application to specific aspects of prostatic disease; the clinically relevant information that has been gleaned thus far from the use of this model system; and advances on the horizon for the expansion of its role in prostate research.

CONCLUSIONS

The MPR model system has contributed substantially to the understanding and treatment of benign and malignant prostatic diseases. Additional modifications in this series of in vivo and in vitro models will likely lead to further advances.

Analysis of cyclin-dependent kinase inhibitor expression and methylation patterns in human prostate cancers

BACKGROUND

Downregulation of genes which negatively control cell cycle progression represents a possible mechanism for prostate tumorigenesis. We examined the expression levels of the p16, p15, p14, and retinoblastoma-susceptibility (RB) genes in primary prostate cancers and human prostate cancer cell lines, and correlated this with the DNA methylation levels of two loci in p16.

METHODS

The mRNA levels of p16, p15, and p14 were examined by reverse transcriptase-PCR (RT-PCR). DNA methylation of the p16 5' CpG island was determined by bisulfite genomic sequencing, while methylation of exon 2 shared by the p16 and p14 genes was measured by a quantitative bisulfite-based technique, methylation-sensitive single-nucleotide primer extension (Ms-SNuPE). RB protein levels were assessed by immunohistochemical staining of histologic sections of normal and tumor prostate tissues, using a monoclonal antibody (mAB).

RESULTS

Overexpression of p16 mRNA was found in 6/9 (67) of prostate tumors compared to the adjacent normal prostate, whereas elevated p14 and p15 levels were only observed in 2/9 (22) and 1/6 (17) of prostate cases, respectively. There was no statistically significant association of grade (P = 0.18) and stage (P = 1.00) of prostate cancer to the elevated p16 levels in the tumors. The p16 5' CpG island was completely unmethylated in these tissues. In contrast, exon 2 of p16/p14 was methylated in both the tumor and normal adjacent prostates, and was increased in 8/11 (73) of tumors relative to normal tissues. There was no association between p16 overexpression and increased p16/p14 exon 2 methylation in these tumors (P = 1.00). Diminished RB levels in prostate tumors that had upregulated p16 mRNA were found, although absent RB was also detected in tumors without elevated p16 levels. The expression levels of the two genes, RB and p16, were not correlated statistically (P = 0.16).

CONCLUSIONS

Our studies show that although the levels of the cell cycle regulators p16, p15, p14, and Rb are altered in prostate cancers, there is no apparent correlation to grade, stage, or any pattern of regulation between the related genes. Exon 2 of p16/p14 is methylated in a majority of prostate tumors compared to the unmethylated upstream 5' region, and may be a potential tumor marker for human prostate cancer.

Transforming growth factor-beta1 and prostate cancer

Transforming growth factor-beta1 (TGF-beta1) is an important regulator of the normal and malignant prostate. In the non-malignant prostate, TGF-beta1 stimulates cell differentiation, inhibits epithelial cell proliferation and induces epithelial cell death. TGF-beta1 is secreted into semen and here it is an important immunosuppressive factor. Prostate cancer cells express high levels of TGF-beta1 and it seems to enhance prostate cancer growth and metastasis by stimulating angiogenesis and by inhibiting immune responses directed against tumour cells. Prostate cancer cells frequently lose their TGF-beta receptors and acquire resistance to the anti-proliferative and pro-apoptotic effects of TGF-beta1. Accordingly, high expression of TGF-beta1 and loss of TGF-beta receptor expression have been associated with a particularly bad prognosis in human prostate cancer patients. TGF-beta1 also seems to be a mediator of castration-induced apoptosis in androgen dependent normal and malignant prostate epithelial cells. The ability of some prostate tumours to avoid castration-induced apoptosis is however not simply due to loss of TGF-beta receptor type I or II expression in the tumour cells, but may also be related to an inability of these cells to up-regulate TGF-beta receptor levels in response to castration or possibly due to defects downstream of the receptors. Short-term therapy-induced changes in the TGF-beta system in prostate tumours can probably be used to predict the long-term response to androgen ablation treatment. Further investigations into the TGF-beta system in the prostate are, however, needed to elucidate how alterations in this system affect the behaviour of prostate tumours, and if this system can be manipulated for therapeutical purposes.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

Elevated levels of circulating interleukin-6 and transforming growth factor-beta1 in patients with metastatic prostatic carcinoma

PURPOSE

Specific cytokines have been found to be secreted by and influence the growth of prostate cancers in cell culture. Interleukin-6 (IL-6), tumor necrosis factor alpha (TNFalpha), granulocyte macrophage-colony stimulating factor (GM-CSF) and transforming growth factor-beta1 (TGF-beta1) have all been closely associated with prostate cancer. We analyzed the levels of these cytokines in the systemic circulation of patients with varying stages of prostate cancer compared to controls.

MATERIALS AND METHODS

Serum IL-6, TNFalpha and GM-CSF were measured using commercially available enzyme linked immunosorbent assays in 5 groups of patients, including controls-19 men presenting to prostate cancer screening with normal digital rectal examination and serum prostate specific antigen (PSA) no greater than 2.0 ng./ml., stage pT2-19 with cancer confined to the prostate in the radical prostatectomy specimen, stage pT3-10 with extraprostatic extension and/or seminal vesicle involvement, stage N1-12 with lymph node metastases at pelvic lymph node dissection, and stage M1-9 with bone metastases. Platelet poor plasma TGF-beta1 was measured using a commercially available enzyme linked immunosorbent assay in controls and patients with stage M1 disease only because it was not available for patients with stages pT2, pT3 and N1 disease. No patient had a history of any other malignancy. All blood specimens were collected before surgery and/or androgen ablation. Statistical analysis was done with the Kruskal-Wallis analysis of variance.

RESULTS

Serum IL-6 and platelet poor plasma TGF-beta1 were significantly elevated in patients with clinically evident metastases (p = 0.0008 and 0.0412, respectively) while serum GM-CSF and TNFalpha were not. IL-6 and TGF-beta1 correlated with increasing serum PSA (p = 0.0335 and 0.0386, respectively). GM-CSF did not correlate with PSA or age. In multivariate analysis TNFalpha correlated with age but not PSA.

CONCLUSIONS

IL-6 and TGF-beta1 correlate with tumor burden as assessed by serum PSA or clinically evident metastases. Further research is needed to determine the response to androgen ablation as well as the source(s) and actions of these cytokines.

Early castration-induced upregulation of transforming growth factor beta1 and its receptors is associated with tumor cell apoptosis and a major decline in serum prostate-specific antigen in prostate cancer patients

BACKGROUND

The mechanism behind castration-induced apoptosis in prostate cells is unknown, but data from other species suggest that transforming growth factor beta1 (TGF-beta1) may be involved.

METHODS

By using quantitative RT-PCR and immunohistochemistry, expression of TGF-beta1 and its receptors type I and II (RI and RII) was studied in normal and tumor areas of core biopsies taken before and 2-11 days after castration therapy. The TGF-beta responses were related to changes in apoptotic index and to changes in serum prostate-specific antigen (PSA).

RESULTS

In normal prostate tissue, apoptosis was generally increased by castration, and apoptosis was accompanied by an increase in TGF-beta1 and RII mRNA levels (P < 0.05). In tumors, apoptosis was seen only in 44% of the cases and in these, but not in the others, TGF-beta1, RI, and RII mRNA levels were increased (P < 0.05). In the patients showing a prognostically favorable PSA response (nadir PSA <5 ng/ml), but not in the others, RI and RII mRNA levels were significantly upregulated (P < 0.05).

CONCLUSIONS

Short-term upregulation of TGF-beta1 and its receptors is associated with apoptosis in human prostate and prostate cancer, and possibly with a favorable clinical outcome after castration therapy.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

TGFbeta signaling is necessary for carcinoma cell invasiveness and metastasis

BACKGROUND

Invasive growth of epithelial tumor cells, a major cause of death from cancer in humans, involves loss of epithelial polarity and dedifferentiation. Transforming growth factor beta (TGFbeta) is regarded as a major tumor suppressor during early tumor development because it inhibits cell-cycle progression and tumor growth. Many dedifferentiated, late-stage tumors are resistant to growth inhibition by TGFbeta, however, and even secrete TGFbeta. In line with this, TGFbeta is involved in angiogenesis, wound healing and epithelial-mesenchymal transition (EMT) during development. Ha-Ras-transformed mammary epithelial cells (EpRas) undergo TGFbeta-induced EMT maintained via a TGFbeta autocrine loop. Thus, we have analyzed whether signal transduction by the TGFbeta receptor (TGFbetaR) is required for local tumor cell invasion and metastasis.

RESULTS

A dominant-negative type II TGFbetaR (TGFbetaRII-dn) was expressed using retroviral vectors in EpRas cells and highly metastatic mesenchymal mouse colon carcinoma cells (CT26). In both cell types, TGFbetaRII-dn blocked TGFbetaR signaling and heavily delayed tumor formation. In EpRas cells, TGFbetaRII-dn prevented EMT. In the dedifferentiated mesenchymal CT26 cells, TGFbetaRII-dn caused mesenchymal-to-epithelial transition and inhibited their in vitro invasiveness in several assays. In addition, TGFbetaRII-dn completely abolished metastasis formation by CT26 cells. Furthermore, several human carcinoma lines lost in vitro invasiveness when treated with neutralizing TGFbeta antibodies or soluble receptor variants. Finally, human colon carcinoma cells (hnPCC) expressing a mutated, non-functional TGFbetaRII were non-invasive in vitro, a defect restored by re-expressing wild-type TGFbetaRII.

CONCLUSIONS

Cell-autonomous TGFbeta signaling is required for both induction and maintenance of in vitro invasiveness and metastasis during late-stage tumorigenesis. TGFbetaRII therefore represents a potential target for therapeutical intervention in human tumorigenesis.

Transforming growth factor beta1 is associated with angiogenesis, metastasis, and poor clinical outcome in prostate cancer

BACKGROUND

Prostate tumors express high levels of transforming growth factor-beta1 (TGF-beta1) and seem to acquire resistance to its antiproliferative effects with tumor progression. Moreover, TGF-beta1 could be involved in tumor-promoting processes such as angiogenesis, cell migration, and immunosuppression.

METHODS

Immunoreactivity for TGF-beta1 and its receptors type I and type II (TGFbeta-RI and TGFbeta-RII), tumor vascular count, and cell proliferation were studied in 73 cases of prostate cancer, diagnosed between 1975-1983 and followed with surveillance.

RESULTS

Patients with tumor overproduction of TGF-beta1 had shorter median cancer-specific survival than patients with normal TGF-beta1 immunoreactivity (5.0 vs. 10 years, P = 0.006). Furthermore, increased TGF-beta1 staining was associated with tumor grade, high vascular counts, and metastasis (P = 0.02, 0.02, and 0.01, respectively). Patients with loss of tumor TGFbeta-RII expression in combination with TGF-beta1 overproduction showed particularly short survival (2.6 vs. 10 years, P = 0.0000), when compared to patients with normal immunoreactivity.

CONCLUSIONS

Overproduction of TGF-beta1 and loss of TGFbeta-RII expression are associated with poor clinical outcome in prostate cancer, and TGF-beta1 may promote tumor progression by stimulating angiogenesis and metastasis.

Transforming growth factor beta 1 and its receptor types I and II. Comparison in human normal prostate, benign prostatic hyperplasia, and prostatic carcinoma

An immunohistochemical and semiquantitative comparative study of transforming growth factor beta 1 (TGF-beta 1) and its receptor types I (TGF-beta RI) and II (TGF-beta RII) was carried out in normal prostates and in the prostates from men with benign prostatic hyperplasia (BPH), and men with prostatic adenocarcinoma. Immunoreaction to TGF-beta 1 was limited to the basal epithelial cells in the normal prostates. Some cells in the connective tissue stroma were also stained. In BPH immunolabelling was also observed in columnar (secretory) cells of the epithelium. In prostatic adenocarcinoma, all epithelial cell types were intensely immunostained. Some stromal cells were also stained. Immunostaining to TGF-beta RI was only present in the basal cells in normal prostates. In BPH, this immunoreaction was found in the whole epithelium and in some stromal cells. In prostatic cancer, the immunostaining pattern for this receptor was similar to that of BPH but more intense in the epithelial cells. Immunoreactivity to TGF-beta RII appeared in some basal cells and some scattered columnar cells of the normal prostate epithelium. In the BPH sections, this pattern was maintained, and a weak immunolabelling was also observed in the stroma. In prostate cancer, all epithelial cells appeared intensely labelled. In the stroma, immunolabelling was similar to that of the BPH specimens. The results of the present study suggest that, in normal prostates, only the basal cells of the epithelium possess both receptor types, and hence can transduce TGF-beta 1 signal intracellularly. The basal cells can also secrete this growth factor which would act as an autocrine inhibitory growth factor for them. In addition, TGF-beta 1 is secreted in some zones by stromal cells, acting then as a paracrine growth factor for basal cells in those areas. In BPH, in addition to the basal cells, some secretory columnar cells also secrete TGF-beta 1 and possess both types of TGF-beta 1 receptors, and thus, both epithelial cell types are susceptible to TGF-beta 1 action. Since both receptor types are also present in some stromal cells, these cells also perform an autocrine secretion, in addition to their paracrine secretion to the epithelial cells. TGF-beta RIIs seem to be more numerous than TGF-beta RIs and this lead us to hypothesize that these incomplete receptors might be a protection against the inhibition caused by TGF-beta 1 action. In prostatic carcinoma all cell types display the same characteristics as in BPH, although both receptor types are found in similar numbers, and thus, the above mentioned protection would not occur.

Induction of smooth muscle cell phenotype in cultured human prostatic stromal cells

Stromal cells are key regulators of growth and differentiation in the adult human prostate. Alterations in the stroma are believed to initiate the development of benign prostatic hyperplasia, and stromal-epithelial interactions may have a role in malignant progression. The prostatic stroma is composed of two major cell types, smooth muscle cells and fibroblasts. Cell cultures from the prostatic stroma have been established by several investigators, but the phenotype of these cells has not been extensively characterized and it is not clear whether they are fibroblastic or smooth muscle-like. In this study, the response of stromal cells cultured from normal prostatic tissues to transforming growth factor-beta (TGF beta) was investigated. We confirmed a previous report that TGF beta inhibited the growth of prostatic stromal cells in serum-containing medium, and showed that inhibition also occurred in serum-free medium. Growth inhibition by TGF beta was irreversible after 24 to 72 h of exposure. In the absence of TGF beta, cells were fibroblastic and expressed vimentin and fibronectin but little alpha-smooth muscle actin. After 3 days of exposure to 1 ng/ml of TGF beta, the majority of cells expressed alpha-smooth muscle actin and desmin, as demonstrated by immunocytochemistry and immunoblot analysis. This effect was specific and alpha-smooth muscle actin was not induced by two other growth-inhibitory factors, retinoic acid or 1,25-dihydroxyvitamin D3. These results suggest that TGF beta is an important regulator of growth and differentiation of prostatic stromal cells and that a smooth muscle cell phenotype is promoted in the presence of TGF beta.

Expression of transforming growth factors beta-1, beta 2 and beta 3 in human bladder carcinomas

We previously detected elevated transforming growth factor beta-1 (TGF-beta1) serum levels in patients with invasive bladder carcinomas. In this study, we therefore investigated whether elevated serum levels correlate with enhanced TGF-beta expression in human bladder tumours. mRNA levels of TGF-beta1, -beta2 and -beta3 were reduced in bladder tumour tissue to 86%, 68% and 56%, respectively, of the levels in normal urothelium. On the other hand, TGF-beta1 protein levels were found to be higher in superficial tumours (Ta-T1) (mean level of 0.153 ng mg(-1)) and in invasive T2/T3 tumours (mean level of 0.104 ng mg(-1)) compared with normal urothelium (mean level of 0.065 ng mg(-1)). Invasive T4 tumours, however, contained only low amounts of TGF-beta1 (mean level of 0.02 ng mg(-1)). Neither in mean nor in individual patients were serum and tissue TGF-beta levels correlated with each other. Cell culture experiments on primary bladder cells revealed a 57% decrease in TGF-beta1 mRNA levels in tumour compared with normal epithelial cells. Tumour epithelial cells contained about two times higher levels of TGF-beta2 and TGF-beta3 mRNA than normal epithelial cells. Fibroblasts expressed about the same amount of TGF-beta1 or TGF-beta2 as epithelial cells. Yet, fibroblasts released only 19% and 13% of the amount secreted by tumour epithelial cells into the supernatant. TGF-beta3, on the other hand, was expressed by fibroblasts with higher levels than by epithelial cells. TGF-beta1 was the predominent isoform in bladder tissue and cells at protein as well as on mRNA levels indicating that TGFs-beta2 and -beta3 are of minor importance in bladder cancer. In summary, there is a lack of correlation between TGF-beta serum levels and TGF-beta expression in tumour tissue in bladder cancer.

Expression of transforming growth factor-beta receptor type I and type II in rat ventral prostate and Dunning R3327 PAP adenocarcinoma in response to castration and oestrogen treatment

In the normal prostate, transforming growth factor-beta 1 (TGF-beta 1) inhibits epithelial cell growth and is associated with apoptosis. The role of TGF-beta 1 in prostate cancer remains, however, unclear. In this work, the expression of TGF-beta receptor type I and II (TGF beta-RI and TGF beta-RII) in the Dunning R3327 PAP adenocarcinoma was studied, after castration and oestrogen treatment. Since castration induces apoptosis in the rat ventral prostate (VP) [21], but not in the Dunning R3327 PAP tumour [46], the TGF-beta receptor levels in the tumour were compared to the receptor levels in the VP. Methods used were competitive reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. In the VP, TGF beta-RI and TGF beta-RII expressions were increased after castration, indicating a negative regulation of TGF beta receptors by androgens. In the Dunning tumour, TGF beta-RI and TGF beta-RII levels were elevated and only TGF beta-RI showed a clear-cut increase after castration. The receptors were located in epithelial and smooth muscle cells in the VP and mainly in epithelial cells in the Dunning tumour. In conclusion, the elevated TGF beta receptor levels and the diminished androgen regulation of TGF beta-RII in the tumour distinguish the Dunning R3327 PAP tumour from the normal prostate and need to be further elucidated.

Transforming growth factor beta as a clinical biomarker for prostate cancer

OBJECTIVES

Tumor biomarkers to detect prostate cancer earlier may reduce prostate cancer deaths. Transforming growth factor-beta1 and -beta2 (TGF-beta1 and -beta2) become overexpressed in prostate cancer and might be useful tumor markers of prostate cancer.

METHODS

Plasma and urinary TGF-beta1 and plasma TGF-beta2 levels were studied preoperatively in 74 consecutive patients who had prostate cancer and underwent radical prostatectomy and were compared with those of 29 similarly aged male control patients who had no clinical evidence of prostate cancer.

RESULTS

Plasma TGF-beta1 levels were similar in both prostate cancer and control groups and did not correlate with serum prostate-specific antigen (PSA), clinical and pathologic stages, or Gleason grade. Urinary TGF-beta1 levels, however, increased 3.5-fold in patients with prostate cancer relative to controls and tended to be higher with advancing clinical and pathologic stages. Plasma TGF-beta2 levels, like plasma TGF-beta1 levels, were similar for both the study and control groups, but when stratified by pathologic stage or Gleason grade, patients with prostate cancer with pathologic Stage T2a and Gleason grade of 3 or less had significantly increased plasma TGF-beta2 levels as compared with either control patients or patients with prostate cancer with pathologic Stages T2b/T2c and T3/T4 or Gleason grade of 4 or more, suggesting that early prostate cancer may contribute to plasma TGF-beta2 levels.

CONCLUSIONS

Unlike plasma TGF-beta1 levels, urinary TGF-beta1 and plasma TGF-beta2 levels were higher in patients with prostate cancer and may be useful biomarkers of prostate cancer.

Expression of transforming growth factor beta 1 (TGF beta 1), -beta 2, and- beta 3 by cultured human prostate cells

Transforming growth factor beta s (TGF beta s) are members of a superfamily of polypeptides that control cell cycle progression and a variety of other cellular activities. TGF beta family members, -beta 1, -beta 2, and -beta 3, have been identified in prostate. The levels of expression of these TGF beta isotypes have been reported to vary with the pathologic state of the prostate. While the significance of these observations remains to be elucidated there is little doubt that TGF beta s play an important role in controlling growth of the prostate. The prostatic cells expressing TGF beta s have not been identified. This information would provide insight into the physiologic role of TGF beta s and suggest ways that growth control may be altered in prostate disease. We used stromal (PS) and epithelial (PE) cells, cultured from normal human prostate and benign prostatic hyperplasia (BPH), to study the effect of TGF beta s on cell proliferation and TGF beta transcript and protein expression. The proliferation of PS and PE was inhibited by pM quantities of TGF beta 1, -beta 2, and -beta 3. Both cell types expressed transcripts for all three TGF beta isotypes, but PS primarily secreted TGF beta 1, whereas PE secreted more TGF beta 2 than TGF beta 1. These observations suggest that TGF beta s are antiproliferative agents in vivo, and that the stroma is the source of TGF beta 1 while the epithelium is the major source of TGF beta 2 in prostate. There were no significant differences in the growth response to TGF beta s, the TGF beta-isotype expressed, or the amount of TGF beta secreted by cells cultured from normal prostate or BPH.

TGF-beta1 and Ha-Ras collaborate in modulating the phenotypic plasticity and invasiveness of epithelial tumor cells

Metastasis of epithelial tumor cells can be associated with the acquisition of fibroblastoid features and the ability to invade stroma and blood vessels. Using matched in vivo and in vitro culture systems employing fully polarized, mammary epithelial cells, we report here that TGF-beta1 brings about these changes in Ras-transformed cells but not in normal cells. When grown in collagen gels in the absence of TGF-beta, both normal and Ras-transformed mammary epithelial cells form organ-like structures in which the cells maintain their epithelial characteristics. Under these conditions, treatment of normal cells with TGF-beta results in growth arrest. The same treatment renders Ras-transformed epithelial cells fibroblastoid, invasive, and resistant to growth inhibition by TGF-beta. After this epithelial-fibroblastoid conversion, the Ras-transformed cells start to secrete TGF-beta themselves, leading to autocrine maintenance of the invasive phenotype and recruitment of additional cells to become fibroblastoid and invasive. More important, this cooperation of activated Ha-Ras with TGF-beta1 is operative during in vivo tumorigenesis and, as in wound healing processes, is dependent on epithelial-stromal interactions.

Transforming growth factor beta 1 expression in human colorectal tumours: an independent prognostic marker in a subgroup of poor prognosis patients

Members of the transforming growth factor beta (TGF-beta family, in particular TGF-beta 1, are some of the most potent inhibitory growth factors in a variety of cell types. Resistance to TGF-beta 1-induced growth inhibition is frequently observed in colorectal carcinomas and is associated with tumour progression. Perturbations of TGF-beta 1 expression and function, therefore, may contribute to the loss of some constraints on tumour cell growth. In this study we have examined the expression of TGF-beta 1 and its precursor latency-associated peptide (LAP)-TGF-beta in human colorectal tumours using immunohistochemical techniques. In 86% of the tumours the LAP-TGF-beta complex was present in both the stromal and epithelial cells, whereas the mature TGF-beta 1 peptide was expressed in the glandular epithelium of 58.3% of these tumours. Intense staining for TGF-beta 1 was positively associated with advanced Dukes' stage. Furthermore, there was a significant correlation between the presence of TGF-beta 1 in the tumours and a shorter post-operative survival. This was most significant in a subgroup of patients who had received only a palliative operation. These results suggest that TGF-beta 1 expression may be useful as an independent prognostic indicator for a subgroup of patients who have a particularly poor prognosis.

Regulation of prostatic growth and function by peptide growth factors

Polypeptide growth factors are positive and negative regulators of prostatic growth and function. Expression and biological effects of epidermal growth factor (EGF), transforming growth factors (TGFs) alpha and beta, fibroblast growth factors (FGFs), and insulin-like growth factors (IGFs) in the prostate have been extensively studied. EGF and TGF alpha, which share the same receptor, are strong mitogens for prostatic epithelial and stromal cells. Their paracrine mode of action in normal tissue and early-stage tumors is apparently altered towards an autocrine stimulation in hormone-independent tumors, which gain the ability to produce TGF alpha by themselves. TGF beta has a dual role in the regulation of prostatic growth. It inhibits growth of prostatic epithelial cells in culture and mediates programmed cell death after androgen withdrawal. However, advanced prostatic carcinomas become insensitive to the inhibitory effect of TGF beta. Several members of the FGF family have been identified in the prostate. They are mainly or exclusively expressed in the stromal cells, and stimulate the epithelial cells. In the rat Dunning tumor model, progression is accompanied by distinct changes in the expression of FGFs and their receptors. In the hyperplastic tissue, basic FGF (bFGF) is accumulated. This growth factor is also a potent angiogenic inducer, expression of which may determine the metastatic capability of a tumor. IGFs are paracrine growth stimulators in the normal and hyperplastic prostate. It is still under consideration whether prostatic cancer cells gain the ability to produce IGF-I by themselves and thus shift to an autocrine mode of IGF-I stimulation. Growth factors also interact with the androgen-signaling pathway. IGF-I in particular, other growth factors as well, can activate the androgen receptor.

The role of fibroblasts in tumor behavior

The prominent desmoplastic or stromal reaction seen in many invasive carcinomas suggests that stromal cells play a role in cancer pathogenesis. Investigations based on cell typing, using antibodies to cytoskeletal constituents, have revealed that most tumors contain various types of fibroblasts. Stromal cells with myofibroblastic differentiation features are the predominant cell type at the periphery of epithelial tumors. These tumor-activated fibroblasts play a major role in tumor development and spread, affecting the proliferation, differentiation, invasion or regression of cancer cells. This review considers the events inducing the different fibroblastic responses and the role of tumor-activated fibroblasts in both tumor development and anti-cancer treatments.

Stromal inhibition of prostatic epithelial cell proliferation not mediated by transforming growth factor beta

The paracrine influence of prostatic stroma on the proliferation of prostatic epithelial cells was investigated. Stromal cells from the human prostate have previously been shown to inhibit anchorage-dependent as well as anchorage-independent growth of the prostatic tumour epithelial cell lines PC-3 and LNCaP. Antiproliferative activity, mediated by a diffusible factor in the stromal cell conditioned medium, was found to be produced specifically by prostatic stromal cells. In the present study the characteristics of this factor were examined. It is demonstrated that prostate stroma-derived inhibiting factor is an acid- and heat-labile, dithiothreitol-sensitive protein. Although some similarities with type beta transforming growth factor (TGF-beta)-like inhibitors are apparent, evidence is presented that the factor is not identical to TGF-beta or to the TGF-beta-like factors activin and inhibin. Absence of TGF-beta activity was shown by the lack of inhibitory response of the TGF-beta-sensitive mink lung cell line CCL-64 to prostate stromal cell conditioned medium and to concentrated, partially purified preparations of the inhibitor. Furthermore, neutralising antibodies against TGF-beta 1 or TGF-beta 2 did not cause a decline in the level of PC-3 growth inhibition caused by partially purified inhibitor. Using Northern blot analyses, we excluded the involvement of inhibin or activin. It is concluded that the prostate stroma-derived factor may be a novel growth inhibitor different from any of the currently described inhibiting factors.