Transforming growth factor beta and prostate cancer

Emerging role of transforming growth factor-β-regulated long non-coding RNAs in prostate cancer pathogenesis

Prostate cancer (PCa) is the most common malignancy in men. Despite aggressive therapy involving surgery and hormonal treatments, the recurrence and emergence of metastatic castration-resistant prostate cancer (CRPCa) remain a major challenge. Dysregulation of the transforming growth factor-β (TGF-β) signaling pathway is crucial to PCa development and progression. This also contributes to androgen receptor activation and the emergence of CRPC. In addition, TGF-β signaling regulates long non-coding RNA (lncRNA) expression in multiple cancers, including PCa. Here, we discuss the complex regulatory network of lncRNAs and TGF-β signaling in PCa and their potential applications in diagnosing, prognosis, and treating PCa. Further investigations on the role of lncRNAs in the TGF-β pathway will help to better understand PCa pathogenesis.

Neferine attenuates development of testosterone-induced benign prostatic hyperplasia in mice by regulating androgen and TGF-β/Smad signaling pathways

Benign prostatic hyperplasia (BPH) is a common urinary disease among the elderly, characterized by abnormal prostatic cell proliferation. Neferine is a dibenzyl isoquinoline alkaloid extracted from Nelumbo nucifera and has antioxidant, anti-inflammatory and anti-prostate cancer effects. The beneficial therapeutic effects and mechanism of action of neferine in BPH remain unclear. A mouse model of BPH was generated by subcutaneous injection of 7.5 mg/kg testosterone propionate (TP) and 2 or 5 mg/kg neferine was given orally for 14 or 28 days. Pathological and morphological characteristics were evaluated. Prostate weight, prostate index (prostate/body weight ratio), expression of type Ⅱ 5α-reductase, androgen receptor (AR) and prostate specific antigen were all decreased in prostate tissue of BPH mice after administration of neferine. Neferine also downregulated the expression of pro-caspase-3, uncleaved PARP, TGF-β1, TGF-β receptor Ⅱ (TGFBR2), p-Smad2/3, N-cadherin and vimentin. Expression of E-cadherin, cleaved PARP and cleaved caspase-3 was increased by neferine treatment. 1-100 μM neferine with 1 μM testosterone or 10 nM TGF-β1 were added to the culture medium of the normal human prostate stroma cell line, WPMY-1, for 24 h or 48 h. Neferine inhibited cell growth and production of reactive oxygen species (ROS) in testosterone-treated WPMY-1 cells and regulated the expression of androgen signaling pathway proteins and those related to epithelial-mesenchymal transition (EMT). Moreover, TGF-β1, TGFBR2 and p-Smad2/3, N-cadherin and vimentin expression were increased but E-cadherin was decreased after 24 h TGF-β1 treatment in WPMY-1 cells. Neferine reversed the effects of TGF-β1 treatment in WPMY-1 cells. Neferine appeared to suppress prostate growth by regulating the EMT, AR and TGF-β/Smad signaling pathways in the prostate and is suggested as a potential agent for BPH treatment.

Shear loaded osteocyte-like-cells affect epithelial and mesenchymal gene expression in DU145 prostate cancer cells, while decreasing their invasion in vitro

Once prostate cancer (PC) metastasizes towards bone the 5-year survival rates drop with 70%, but it is largely unknown why. Bone is continuously mechanically loaded, which likely modulates the paracrine signaling from osteocytes towards PC cells to affect tumor behavior. We hypothesize that shear loaded osteocytes affect PC cell proliferation, invasion and epithelial and mesenchymal-related gene and protein expression. We cultured human DU145 cells, a commonly used cell line for prostate cancer metastases, in the conditioned medium (CM) from shear loaded or unloaded human osteocyte-like-cells (OCYLCs) for 1 and 3 days and assessed their number by staining nuclei with DAPI, their invasion by performing an invasion assay, and epithelial-to-mesenchymal (EMT)-related gene and protein expression by qPCR and immunocytochemistry. CM of shear loaded OCYLCs did not affect DU145 cell number compared to CM of static cultured OCYLCs, but decreased their invasion 1.34-fold. CM of shear loaded OCYLCs enhanced expression of epithelial genes: SYND1 and CDH1 after day 1, while it also enhanced CDH1 after day 3. CM of shear loaded osteocytes enhanced mesenchymal genes: VMN, Snail and MIP2 after day 1, while it decreased expression of mesenchymal CYR61 after day 3. We conclude that CM of shear loaded OCYLCs does not affect DU145 cell proliferation, but decreases their invasion, and differentially affects their EMT-related gene expression. Identifying paracrine signals from shear loaded osteocytes that decrease PC cell invasion may provide novel leads in developing treatments for bone metastases from PC.

Metformin regulates multiple signaling pathways within castration-resistant human prostate cancer cells

Background

The biguanide metformin has been shown to not only reduce circulating glucose levels but also suppress in vitro and in vivo growth of prostate cancer. However, the mechanisms underlying the anti-tumor effects of metformin in advanced prostate cancers are not fully understood. The goal of the present study was to define the signaling pathways regulated by metformin in androgen-receptor (AR) positive, castration-resistant prostate cancers.

Methods

Our group used RNA sequencing (RNA-seq) to examine genes regulated by metformin within the C4–2 human prostate cancer cell line. Western blot analysis and quantitative RT-PCR were used to confirm alterations in gene expression and further explore regulation of protein expression by metformin.

Results

Data from the RNA-seq analysis revealed that metformin alters the expression of genes products involved in metabolic pathways, the spliceosome, RNA transport, and protein processing within the endoplasmic reticulum. Gene products involved in ErbB, insulin, mTOR, TGF-β, MAPK, and Wnt signaling pathways are also regulated by metformin. A subset of metformin-regulated gene products were genes known to be direct transcriptional targets of p53 or AR. Western blot analyses and quantitative RT-PCR indicated these alterations in gene expression are due in part to metformin-induced reductions in AR mRNA and protein levels.

Conclusions

Together, our results suggest metformin regulates multiple pathways linked to tumor growth and progression within advanced prostate cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10115-3.

Long non-‑coding RNA SNHG16 functions as a tumor activator by sponging miR‑373‑3p to regulate the TGF‑β‑R2/SMAD pathway in prostate cancer

Long non‑coding RNAs (lncRNAs) are involved in the pathogenesis of prostate cancer (PCa) as competitive endogenous RNA. The present study aimed to investigate the molecular mech--anisms of lncRNA small nucleolar RNA host gene 16 (SNHG16) in the proliferation and metastasis of PCa cells. Cancer tissues and adjacent normal tissues were collected from 80 patients with PCa who did not receive any treatment. Reverse transcription‑quantitative PCR analysis was performed to detect the expression levels of SNHG16, hsa‑microRNA (miRNA/miR)‑373‑3p and transforming growth factor‑β receptor type 2 (TGF‑β‑R2), and Spearman's correlation coefficient analysis was performed to assess the correlations between these molecules. Furthermore, the effects of SNHG16 knockdown and overexpression on the biological functions of DU‑145 PCa cells and TGF‑β‑R2/SMAD signaling were analyzed. The dual‑luciferase reporter assay was performed to assess the associations between SNHG16 and miR‑373‑3p, and TGF‑β‑R2 and miR‑373‑3p, the effects of which were verified via rescue experiments. The results demonstrated that the expression levels of SNHG16 and TGF‑β‑R2 were significantly upregulated in PCa tissues, whereas miR‑373‑3p expression was significantly downregulated (P<0.001). In addition, negative correlations were observed between SNHG16 and miR‑373‑3p (rho, ‑0.631) and miR‑373‑3p and TGF‑β‑R2 (rho, ‑0.516). Overexpression of SNHG16 significantly promoted the proliferation, migration and invasion of PCa cells (P<0.05), and significantly increased the protein expression levels of TGF‑β‑R2, phosphorylated (p)‑SMAD2, p‑SMAD3, c‑Myc and E2F4 (P<0.001). Notably, the results revealed that miR‑373‑3p is a target of SNHG16, and miR‑373‑3p knockdown rescued short hairpin (sh)‑SNHG16‑suppressed cellular functions by promoting TGF‑β‑R2/SMAD signaling. The results also revealed that miR‑373‑3p targets TGF‑β‑R2. Notably, transfection with miR‑373‑3p inhibitor rescued sh‑TGF‑β‑R2‑suppressed cell proliferation and migration. Taken together, the results of the present study suggest that SNHG16 promotes the proliferation and migration of PCa cells by targeting the miR‑373‑3p/TGF‑β‑R2/SMAD axis.

Developmental estrogenization: Prostate gland reprogramming leads to increased disease risk with aging

While estrogens are involved in normal prostate morphogenesis and function, inappropriate early-life estrogenic exposures, either in type, dose or timing, can reprogram the prostate gland and lead to increased disease risk with aging. This process is referred to as estrogen imprinting or developmental estrogenization of the prostate gland. The present review discusses published and new evidence for prostatic developmental estrogenization that includes extensive research in rodent models combined with epidemiology findings that together have helped to uncover the architectural and molecular underpinnings that promote this phenotype. Complex interactions between steroid receptors, developmental morphoregulatory factors, epigenetic machinery and stem-progenitor cell targets coalesce to hard wire structural, cellular and epigenomic reorganization of the tissue which retains a life-long memory of early-life estrogens, ultimately predisposing the gland to prostatitis, hyperplasia and carcinogenesis with aging.

A novel highly potent trivalent TGF-β receptor trap inhibits early-stage tumorigenesis and tumor cell invasion in murine Pten-deficient prostate glands

The effects of transforming growth factor beta (TGF-β) signaling on prostate tumorigenesis has been shown to be strongly dependent on the stage of development, with TGF-β functioning as a tumor suppressor in early stages of disease and as a promoter in later stages. To study in further detail the paradoxical tumor-suppressive and tumor-promoting roles of the TGF-β pathway, we investigated the effect of systemic treatment with a TGF-β inhibitor on early stages of prostate tumorigenesis. To ensure effective inhibition, we developed and employed a novel trivalent TGF-β receptor trap, RER, comprised of domains derived from the TGF-β type II and type III receptors. This trap was shown to completely block TβRII binding, to antagonize TGF-β1 and TGF-β3 signaling in cultured epithelial cells at low picomolar concentrations, and it showed equal or better anti-TGF-β activities than a pan TGF-β neutralizing antibody and a TGF-β receptor I kinase inhibitor in various prostate cancer cell lines. Systemic administration of RER inhibited prostate tumor cell proliferation as indicated by reduced Ki67 positive cells and invasion potential of tumor cells in high grade prostatic intraepithelial neoplasia (PIN) lesions in the prostate glands of Pten conditional null mice. These results provide evidence that TGF-β acts as a promoter rather than a suppressor in the relatively early stages of this spontaneous prostate tumorigenesis model. Thus, inhibition of TGF-β signaling in early stages of prostate cancer may be a novel therapeutic strategy to inhibit the progression as well as the metastatic potential in patients with prostate cancer.

Fibrillar collagen genes are not coordinately upregulated with TGF β1 expression in finasteride-treated prostate

Benign prostatic hyperplasia (BPH) is the most common cause of lower urinary tract symptoms (LUTS) in older men. In this regard, recent studies have attempted to define the relationships between prostatic fibrosis, LUTS, and increased expression of transforming growth factor β1 (TGF β1) in BHP. Therapeutic approaches for BPH such as 5-α-reductase inhibitors and alpha-adrenergic blocking agents increase TGF β1 expression in the prostatic tissue. Here, we investigated the effects of the 5-α-reductase inhibitor-finasteride-on rat ventral prostate tissue, especially with regard to the tissue distribution and gene expression of fibrillar collagens. Adult Wistar rats (n = 15) were treated with finasteride (25 mg/kg/day) by subcutaneous injection for 7 and 30 days. Age-matched, vehicle-treated (n = 15) adult Wistar rats were used as control. Finasteride treatment reduced prostate size and increased the area of types I and III collagen fibers in the prostatic stroma. As expected, TGF β1 mRNA expression was upregulated by finasteride treatment. However, COL1A1 and COL3A1 mRNA expressions decreased after both 7 and 30 days of finasteride treatment, suggesting that finasteride treatment promotes prostate parenchyma and stroma changes, which lead to the observed types I and III collagen remodeling without de novo collagen synthesis. The upregulation of TGF β1 mRNA and protein associated with the 5-α-reductase inhibitor is more closely related to epithelial and stromal cell death pathways than to prostatic fibrosis.

Cytochrome P450 17A1 inhibitor abiraterone attenuates cellular growth of prostate cancer cells independently from androgen receptor signaling by modulation of oncogenic and apoptotic pathways

Abiraterone provides significant survival advantages in prostate cancer (PC), however, the current understanding of the molecular mechanisms of abiraterone is still limited. Therefore, the abiraterone impact on androgen receptor (AR)-positive LNCaP and AR-negative PC-3 cells was assessed by cellular and molecular analyses. The present study demonstrated, that abiraterone treatment significantly decreased cell growth, AR expression, and AR activity of AR-positive LNCaP cells. Notably, AR-negative PC-3 cells exhibited comparable reductions in cellular proliferation, associated with DNA fragmentation and pro-apoptotic modulation of p21, caspase-3, survivin, and transforming growth factor β (TGFβ). Our observations suggest that the attenuation of AR signaling is not the only rationale to explain the abiraterone anticancer activity. Abiraterone efficacy may play a more global role in PC progression control than originally hypothesized. In this regard, abiraterone is not only a promising drug for treatment of AR-negative PC stages, even more, abiraterone may represent an alternative for treatment of other malignancies besides prostate cancer.

Dichotomy in the Epigenetic Mark Lysine Acetylation is Critical for the Proliferation of Prostate Cancer Cells

The dynamics of lysine acetylation serve as a major epigenetic mark, which regulates cellular response to inflammation, DNA damage and hormonal changes. Microarray assays reveal changes in gene expression, but cannot predict regulation of a protein function by epigenetic modifications. The present study employs computational tools to inclusively analyze microarray data to understand the potential role of acetylation during development of androgen-independent PCa. The data revealed that the androgen receptor interacts with 333 proteins, out of which at least 92 proteins were acetylated. Notably, the number of cellular proteins undergoing acetylation in the androgen-dependent PCa was more as compared to the androgen-independent PCa. Specifically, the 32 lysine-acetylated proteins in the cellular models of androgen-dependent PCa were mainly involved in regulating stability as well as pre- and post-processing of mRNA. Collectively, the data demonstrate that protein lysine acetylation plays a crucial role during the transition of androgen-dependent to -independent PCa, which importantly, could also serve as a functional axis to unravel new therapeutic targets.

Mechanisms navigating the TGF-β pathway in prostate cancer

Few pharmacotherapies are currently available to treat castration resistant prostate cancer (CRPC), with low impact on patient survival. Transforming growth factor-β (TGF-β) is a multi-functional peptide with opposite roles in prostate tumorigenesis as an inhibitor in normal growth and early stage disease and a promoter in advanced prostate cancer. Dysregulated TGF-β signaling leads to a cascade of events contributing to oncogenesis, including up-regulated proliferation, decreased apoptosis, epithelial-to-mesenchymal transition (EMT) and evasion of immune surveillance. TGF-β signaling pathway presents an appropriate venue for establishing a therapeutic targeting platform in CRPC. Exploitation of TGF-β effectors and their cross talk with the androgen axis pathway will provide new insights into mechanisms of resistance of the current antiandrogen therapeutic strategies and lead to generation of new effective treatment modalities for CRPC. Points of functional convergence of TGF-β with key oncogenic pathways, including mitogen-activated protein kinase (MAPK) and androgen receptor (AR), are discussed as navigated within the EMT landscape in the tumor microenvironment. In this context the emerging anti-TGF-β pharmacotherapies for prostate cancer treatment are considered. Targeting the functional cross-talk between the TGF-β signaling effectors with the androgen axis supports the development of novel therapeutic strategies for treating CRPC with high specificity and efficacy in a personalized-medicine approach.

Restoring TGFβ1 pathway-related microRNAs: possible impact in metastatic prostate cancer development

In developed countries, prostate cancer (PC) is the neoplasia more frequently diagnosed in men. The signaling pathway induced by the transforming growth factor β1 (TGFβ1) has an important role in cell growth, differentiation, and development, the downregulation of this pathway being associated with cancer development. In PC, the activation of this signaling pathway is lost, resulting in favoring of tumor growth, proliferation, and evasion of apoptosis. Several studies have shown that microRNAs (miRNAs), small non-coding RNA, are closely associated with the development, invasion, and metastasis, suggesting that they have a critical role in cancer development. Recently, Smad proteins, the signal transducers of the TGFβ1 signaling pathway, were found to regulate miRNA expression, through both transcriptional and posttranscriptional mechanisms. In this review, we summarize the mechanisms underlying Smad-mediated regulation of miRNA biogenesis and the effects on cancer development, particularly in PC. We identify that TGFβ1-related miR-143, miR-145, miR-146a, and miR-199a may have a key role in the development of prostate cancer metastasis and the restoration of their expression may be a promising therapeutic strategy for PC treatment.

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.

Comprehensive gene expression analysis reveals multiple signal pathways associated with prostate cancer

Prostate cancer (PC) depends on androgenic signaling for growth and survival. To data, the exact molecular mechanism of hormone controlling proliferation and tumorigenesis in the PC remains unclear. Therefore, in this study, we explored the differentially expressed genes (DEGs) and identified featured genes related to hormone stimulus from PC. Two sets of gene expression data, including PC and normal control sample, were downloaded from Gene Expression Omnibus (GEO) database. The t-test was used to identify DEGs between PC and controls. Gene ontology (GO) functional annotation was applied to analyze the function of DEGs and screen hormone-related DEGs. Then these hormone-related DEGs were further analyzed in constructed cancer network and Human Protein Reference Database to screen important signaling pathways they participated in. A total of 912 DEGs were obtained which included 326 up-regulated genes and 586 down-regulated genes. GO functional enrichment analysis identified 50 hormone-related DEGs associated with PC. After pathway and PPI network analysis, we found these hormone-related DEGs participated in several important signaling pathways including TGF-β (TGFB2, TGFB3 and TGFBR2), MAPK (TGFB2, TGFB3 and TGFBR2), insulin (PIK3R3, SHC1 and EIF4EBP1), and p53 signaling pathways (CCND2 and CDKN1A). In addition, a total of five hormone-related DEGs (SHC1, CAV1, RXRA, CDKN1A and SRF) were located in the center of PPI network and 12 hormone-related DEGs formed six protein modules. These important signal pathways and hormone-related DEGs may provide potential therapeutic targets for PC.

Autophagy in prostate cancer and androgen suppression therapy

The role of autophagy is known to be highly complex and context-dependent, leading to both cancer suppression and progression in several tumors including melanoma, breast and prostate cancer. In the present review, recent advances in an understanding of the involvement of autophagy in prostate cancer treatment are described. The regulatory effects of androgens on prostate cancer cell autophagy are particularly discussed in order to highlight the effects of autophagy modulation during androgen deprivation. A critical evaluation of the studies examined in the present review suggests the attractive possibility of autophagy inhibition combined with hormonal therapy as a promising approach for prostate cancer treatment.

Overcoming drug resistance and treating advanced prostate cancer

Most of the prostate cancers (PCa) in advanced stage will progress to castration-resistant prostate cancer (CRPC). Within CRPC group, 50-70% of the patients will develop bone metastasis in axial and other regions of the skeleton. Once PCa cells spread to the bone, currently, no treatment regimens are available to eradicate the metastasis, and cancer-related death becomes inevitable. In 2012, it is estimated that there will be 28,170 PCa deaths in the United States. Thus, PCa bone metastasis-associated clinical complications and treatment resistance pose major clinical challenges. In this review, we will present recent findings on the molecular and cellular pathways that are responsible for bone metastasis of PCa. We will address several novel mechanisms with a focus on the role of bone and bone marrow microenvironment in promoting PCa metastasis, and will further discuss why prostate cancer cells preferentially metastasize to the bone. Additionally, we will discuss novel roles of several key pathways, including angiogenesis and extracellular matrix remodeling in bone marrow and stem cell niches with their relationship to PCa bone metastasis and poor treatment response. We will evaluate how various chemotherapeutic drugs and radiation therapies may allow aggressive PCa cells to gain advantageous mutations leading to increased survival and rendering the cancer cells to become resistant to treatment. The novel concept relating several key survival and invasion signaling pathways to stem cell niches and treatment resistance will be reviewed. Lastly, we will provide an update of several recently developed novel drug candidates that target metastatic cancer microenvironments or niches, and discuss the advantages and significance provided by such therapeutic approaches in pursuit of overcoming drug resistance and treating advanced PCa.

The reactive stroma microenvironment and prostate cancer progression

Reactive stroma initiates during early prostate cancer development and coevolves with prostate cancer progression. Previous studies have defined the key markers of reactive stroma and have established that reactive stroma biology influences prostate tumorigenesis and progression. The stem/progenitor cells of origin and the mechanisms that regulate their recruitment and activation to myofibroblasts or carcinoma-associated fibroblasts are essentially unknown. Key regulatory factors have been identified, including transforming growth factor β, interleukin-8, fibroblast growth factors, connective tissue growth factor, wingless homologs-Wnts, and stromal cell-derived factor-1, among others. The biology of reactive stroma in cancer is similar to the more predictable biology of the stroma compartment during wound repair at sites where the epithelial barrier function is breached and a stromal response is generated. The coevolution of reactive stroma and the biology of how reactive stroma-carcinoma interactions regulate cancer progression and metastasis are targets for new therapeutic approaches. Such approaches are strategically designed to inhibit cancer progression by uncoupling the reactive stroma niche.

Microsatellite instability in sarcoma: fact or fiction?

Microsatellite instability (MSI) is a unique molecular abnormality, indicative of a deficient DNA mismatch repair (MMR) system. Described and characterized in the colorectal cancer literature, the MSI-positive phenotype is predictive of disease susceptibility, pathogenesis, and prognosis. The clinical relevance of MSI in colorectal cancer has inspired similar inquisition within the sarcoma literature, although unfortunately, with very heterogeneous results. Evolving detection techniques, ill-defined sarcoma-specific microsatellite loci and small study numbers have hampered succinct conclusions. The literature does suggest that MSI in sarcoma is observed at a frequency similar to that of sporadic colorectal cancers, although there is little evidence to suggest that MSI-positive tumors share distinct biological attributes. Emerging evidence in Ewing sarcoma has demonstrated an intriguing mechanistic role of microsatellite DNA in the activation of key EWS/FLI-target genes. These findings provide an alternative perspective to the biological implications of microsatellite instability in sarcoma and warrant further investigation using sophisticated detection techniques, sensitive microsatellite loci, and appropriately powered study designs.

Gene variants in the angiogenesis pathway and prostate cancer

Although the causes of prostate cancer are still unknown, numerous studies support the role of genetic factors in the development and progression of this disease. Single nucleotide polymorphisms (SNPs) in key angiogenesis genes have been studied in prostate cancer. In this review, we provide an overview of the current knowledge of the role of genetic variants in the angiogenesis pathway in prostate cancer risk and progression. Of the 17 prostate cancer genome-wide association studies (GWAS) conducted to date, only one identified disease-associated SNPs in a region of an angiogenesis pathway gene. An association was observed between aggressive disease and three intergenic SNPs (rs11199874, rs10749408 and rs10788165) in a region on chromosome 10q26 that encompasses FGFR2. The majority (27/32, 84.4%) of primary candidate gene studies reviewed had a small (n < 800, 20/32, 62.5%) to medium sample size (n = 800-2000, 7/32, 21.9%), whereas only five (15.6%) had a large sample size (n ≥ 2000). Results from the large studies revealed associations with risk and aggressive disease for SNPs in NOS2A, NOS3 and MMP-2 and risk for HIF1-α. Meta-analyses have so far been conducted on FGFR2, TGF-β, TNF-α, HIF1-α and IL10 and the results reveal an association with risk for SNPs in FGFR2 and TGF-β and aggressive disease for SNPs in IL-10. Thus, existing evidence from GWAS and large candidate gene studies indicates that SNPs from a limited number of angiogenesis pathway genes are associated with prostate cancer risk and progression.

Androgen regulation of epithelial-mesenchymal transition in prostate tumorigenesis

Prostate cancer patient mortality is ascribed to the spread of cancerous cells to areas outside the prostate gland and the inability of current treatment strategies to effectively block progression to metastasis. Understanding the cellular mechanisms contributing to the dissemination of malignant cells and metastasis is critically significant to the generation of effective therapeutic modalities for improved patient survival while combating therapeutic resistance. In recent years, the phenomenon of epithelial-mesenchymal transitions (EMTs) has received considerable attention due to accumulating evidence indicating a role for this developmentally conserved process in tumorigenesis. Cancer cells at the invasive edges of tumors undergo EMT under the influence of contextual signals that they receive from the microenvironment, such as TGF-β. Also derived from developmental studies is the fact that EMT induction is reversible; thus, upon removal of EMT-inducing signals, cells occasionally revert to the epithelial state of their cellular ancestors via the process of mesenchymal-epithelial transition. This article discusses the current evidence supporting a central role for EMT and its reverse process, mesenchymal-epithelial transition, in the metastatic progression of prostate cancer to advanced disease and the involvement of androgen signaling in its regulation towards the development of castration-resistant prostate cancer.

Opposite functions of HIF-α isoforms in VEGF induction by TGF-β1 under non-hypoxic conditions

Transforming growth factor (TGF)-β1 has biphasic functions in prostate tumorigenesis, having a growth-inhibitory effect in the early stages, but in the late stages promoting tumor angiogenesis and metastasis. We demonstrate here that tumor-producing TGF-β1 induces vascular endothelial growth factor (VEGF) in prostate cancer cells, and hypoxia-inducible factor (HIF)-1α and HIF-2α has opposite functions in TGF-β1 regulation of VEGF expression under non-hypoxic conditions. The promoter response of VEGF to TGF-β1 was upregulated by the transfection of HIF-2α or siHIF-1α but downregulated by HIF-1α and siHIF-2α. Both HIF-1α and HIF-2α were induced by TGF-β1 at mRNA and protein levels, however, their nuclear translocation was differentially regulated by TGF-β1, suggesting its association with their opposite effects. VEGF induction by TGF-β1 occurred in a Smad3-dependent manner, and the Smad-binding element 2 (SBE2, -992 to -986) and hypoxia response element (-975 to -968) in the VEGF promoter were required for the promoter response to TGF-β1. Smad3 cooperated with HIF-2α in TGF-β1 activation of VEGF transcription and Smad3 binding to the SBE2 site was greatly impaired by knockdown of HIF-2α expression. Moreover, the VEGF promoter response to TGF-β1 was synergistically elevated by co-transfection of Smad3 and HIF-2α but attenuated by HIF-1α in a dose-dependent manner. Additionally, TGF-β1 was found to increase the stability of VEGF transcript by facilitating the cytoplasmic translocation of a RNA-stabilizing factor HuR. Collectively, our data show that tumor-producing TGF-β1 induces VEGF at the both transcription and post-transcriptional levels through multiple routes including Smad3, HIF-2α and HuR. This study thus suggests that autocrine TGF-β1 production may contribute to tumor angiogenesis via HIF-2α signaling under non-hypoxic conditions, providing a selective growth advantage for prostate tumor cells.

"Topological significance" analysis of gene expression and proteomic profiles from prostate cancer cells reveals key mechanisms of androgen response

BACKGROUND

The problem of prostate cancer progression to androgen independence has been extensively studied. Several studies systematically analyzed gene expression profiles in the context of biological networks and pathways, uncovering novel aspects of prostate cancer. Despite significant research efforts, the mechanisms underlying tumor progression are poorly understood. We applied a novel approach to reconstruct system-wide molecular events following stimulation of LNCaP prostate cancer cells with synthetic androgen and to identify potential mechanisms of androgen-independent progression of prostate cancer.

METHODOLOGY/PRINCIPAL FINDINGS

We have performed concurrent measurements of gene expression and protein levels following the treatment using microarrays and iTRAQ proteomics. Sets of up-regulated genes and proteins were analyzed using our novel concept of "topological significance". This method combines high-throughput molecular data with the global network of protein interactions to identify nodes which occupy significant network positions with respect to differentially expressed genes or proteins. Our analysis identified the network of growth factor regulation of cell cycle as the main response module for androgen treatment in LNCap cells. We show that the majority of signaling nodes in this network occupy significant positions with respect to the observed gene expression and proteomic profiles elicited by androgen stimulus. Our results further indicate that growth factor signaling probably represents a "second phase" response, not directly dependent on the initial androgen stimulus.

CONCLUSIONS/SIGNIFICANCE

We conclude that in prostate cancer cells the proliferative signals are likely to be transmitted from multiple growth factor receptors by a multitude of signaling pathways converging on several key regulators of cell proliferation such as c-Myc, Cyclin D and CREB1. Moreover, these pathways are not isolated but constitute an interconnected network module containing many alternative routes from inputs to outputs. If the whole network is involved, a precisely formulated combination therapy may be required to fight the tumor growth effectively.

Role of the VEGFR3/VEGFD receptor axis in TGFbeta1 activation of primary prostate cell lines

BACKGROUND

Reports indicate that vascular endothelial growth factor receptor type 3 (VEGFR3) regulates cellular functions such as invasion, proliferation, and chemo-resistance. However, the exact function of the VEGFR3 signaling axis in prostate epithelial cells is poorly characterized.

METHODS

The goal of this study was to evaluate whether TGFbeta1 in combination with VEGFD can promote pre-malignant invasive activities of intermediate basal cells (IBC-10a) isolated from human prostate cancer (Gleason score 6).

RESULTS

hTERT immortalized IBC-10a cells normally grew as confluent "cobblestoned" monolayers, but treatment with TGFbeta1 (10 ng/ml for 2-6 hr) dissociated the cell-cell junctions and induced VEGFR3 translocation to the cell surface. This event was not inhibited by 10 microM cycloheximide or puromycin, indicating transcription and protein synthesis were not required. We further discovered that TGFbeta1 in combination with VEGFD induced a significant increase in the invasive activity of IBC-10a cells (>26% and 53% after 24 and 48 hr, respectively) in modified Boyden Chamber assays. TGFbetaRII receptor antibodies specifically blocked TGFbeta1 induction of VEGFR3 translocation to the cell surface and blocked VEGFD-induced invasion. Zymograms revealed that TGFbeta1 (and not VEGFR3) stimulated the secretion of MMP-2 and MMP-9, presumably to promote cell invasion. The cell invasion assays confirmed that antibodies specific for TGFbetaII receptor, MMP-2 and MMP-9 and VEGFR3, independently blocked TGFbeta1-induced invasion.

CONCLUSIONS

For the first time, we have demonstrated the mechanism by which TGFbeta1 stimulates VEGFD/VEGFR3 receptor axis activation leading to increased cell migration and invasion by primary intermediate basal cell cultures.

Androgen receptor and growth factor signaling cross-talk in prostate cancer cells

Androgens promote the growth and differentiation of prostate cells through ligand activation of the androgen receptor (AR). Sensitization of the androgenic response by multifunctional growth factor signaling pathways is one of the mechanisms via which AR contributes to the emergence of androgen-independent prostate tumors. The ability of AR to cross-talk with key growth factor signaling events toward the regulation of cell cycle, apoptosis, and differentiation outcomes in prostate cancer cells is established. In this paper, we review the functional interaction between AR and an array of growth factor signal transduction events (including epidermal growth factor; fibroblast growth factor; IGF1; vascular endothelial growth factor; transforming growth factor-beta) in prostate tumors. The significance of this derailed cross-talk between androgens and key signaling networks in prostate cancer progression and its value as a therapeutic forum targeting androgen-independent metastatic prostate cancer is discussed.

Involvement of Cyr61 in growth, migration, and metastasis of prostate cancer cells

Cyr61 has been reported to participate in the development and progression of various cancers; however, its role in prostate cancer (PCa) still remains poorly understood. In this study, we explored the function of Cyr61 in a series of malignant PCa cell lines, including LnCap, Du145, and PC3. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and crystal violet assays demonstrated that Cyr61 was essential for the proliferation of PCa cells. Soft agar assay and xenograft analysis showed that downregulation of Cyr61 suppressed the tumorigenicity of Du145 cells both in vitro and in vivo. Either silencing the cellular Cyr61 by RNA interference or neutralising the endogenous Cyr61 by antibody inhibited the migration of Du145 cells. In contrast, purified protein of Cyr61 promoted the migration of LnCap cells in a dose-dependent manner. These results suggested that Cyr61 was involved in the migration of PCa cells. We also observed the accumulation of mature focal adhesion complexes associated with the impaired migration through Cyr61 downregulation. Also, further studies showed that Cyr61 regulated the level of activated Rac1 as well as its downstream targets, including phosphorylated JNK, E-cadherin, and p27^kip1, which are key molecules involved in cell growth, migration, and invasion. The in vivo mouse tail vein injection experiment revealed that Cyr61 affected the metastatic capacity of Du145 cells, suggesting that Cyr61 was required for prostate tumour metastasis. Altogether, our results demonstrated that Cyr61 played an important role in the tumorigenicity and metastasis of PCa cells, which will benefit the development of therapeutic strategy for PCas.

Broccoli consumption interacts with GSTM1 to perturb oncogenic signalling pathways in the prostate

BACKGROUND

Epidemiological studies suggest that people who consume more than one portion of cruciferous vegetables per week are at lower risk of both the incidence of prostate cancer and of developing aggressive prostate cancer but there is little understanding of the underlying mechanisms. In this study, we quantify and interpret changes in global gene expression patterns in the human prostate gland before, during and after a 12 month broccoli-rich diet.

METHODS AND FINDINGS

Volunteers were randomly assigned to either a broccoli-rich or a pea-rich diet. After six months there were no differences in gene expression between glutathione S-transferase mu 1 (GSTM1) positive and null individuals on the pea-rich diet but significant differences between GSTM1 genotypes on the broccoli-rich diet, associated with transforming growth factor beta 1 (TGFbeta1) and epidermal growth factor (EGF) signalling pathways. Comparison of biopsies obtained pre and post intervention revealed more changes in gene expression occurred in individuals on a broccoli-rich diet than in those on a pea-rich diet. While there were changes in androgen signalling, regardless of diet, men on the broccoli diet had additional changes to mRNA processing, and TGFbeta1, EGF and insulin signalling. We also provide evidence that sulforaphane (the isothiocyanate derived from 4-methylsuphinylbutyl glucosinolate that accumulates in broccoli) chemically interacts with TGFbeta1, EGF and insulin peptides to form thioureas, and enhances TGFbeta1/Smad-mediated transcription.

CONCLUSIONS

These findings suggest that consuming broccoli interacts with GSTM1 genotype to result in complex changes to signalling pathways associated with inflammation and carcinogenesis in the prostate. We propose that these changes may be mediated through the chemical interaction of isothiocyanates with signalling peptides in the plasma. This study provides, for the first time, experimental evidence obtained in humans to support observational studies that diets rich in cruciferous vegetables may reduce the risk of prostate cancer and other chronic disease.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00535977.

WDR19 expression is increased in prostate cancer compared with normal cells, but low-intensity expression in cancers is associated with shorter time to biochemical failures and local recurrence

PURPOSE

Prostate cancer is the third leading cause of cancer death in the United States, following lung and colorectal cancer. We previously identified WDR19 as a prostate-specific, androgen-regulated gene. Here, we evaluate its utility as a prostate cancer tissue marker for diagnosis and prognostic evaluation.

EXPERIMENTAL DESIGN

Real-time quantitative PCR was done on a panel of prostate tissue isolated by laser capture microdissection. After generating antibodies against WDR19, tissue microarrays (TMA) were employed to compare WDR19 expression between normal, benign prostatic hyperplasia, and prostate cancer tissue.

RESULTS

Using microarrays and real-time quantitative PCR, we showed that WDR19 mRNA expression was increased in cancer. We further showed that WDR19 protein is localized to cytoplasmic subcellular granules and is expressed exclusively in prostate epithelia. Large-scale immunohistochemical staining using TMAs reveals a significant percentage of increase in intensely staining tissue cores in cancer tissue when compared with normal or benign prostatic hyperplastic tissue. Based on the analysis of a separate TMA for which clinical follow-up information was available, low-intensity WDR19 staining was significantly associated with decreased time to biochemical failure (P = 0.006) and with decreased time to locoregional recurrence (P = 0.050).

CONCLUSIONS

WDR19 should be added to the list of prostate cancer tissue markers. The continued expansion of a multiple-marker panel will conceivably increase the sensitivity and specificity of prostate cancer diagnosis and prognosis.

Global expression analysis of prostate cancer-associated stroma and epithelia

Characterization of gene expression profiles in tumor cells and the tumor microenvironment is an important step in understanding neoplastic progression. To date, there are limited data available on expression changes that occur in the tumor-associated stroma as either a cause or consequence of cancer. In the present study, we employed a 54,000 target oligonucleotide microarray to compare expression profiles in the 4 major components of the microenvironment: tumor epithelium, tumor-associated stroma, normal epithelium, and normal stroma. Cells from 5 human, whole-mount prostatectomy specimens were microdissected and the extracted and amplified mRNA was hybridized to an Affymetrix Human Genome U133 Plus 2.0 GeneChip. Using the intersection of 2 analysis methods, we identified sets of differentially expressed genes among the 4 components. Forty-four genes were found to be consistently differentially expressed in the tumor-associated stroma; 35 were found in the tumor epithelium. Interestingly, the tumor-associated stroma showed a predominant up-regulation of transcripts compared with normal stroma, in sharp contrast to the overall down-regulation seen in the tumor epithelium relative to normal epithelium. These data provide insight into the molecular changes occurring in tumor-associated stromal cells and suggest new potential targets for future diagnostic, imaging, or therapeutic intervention.

Steroid hormones and carcinogenesis of the prostate: the role of estrogens

Androgens have long been known to be the major sex hormones that target the prostate during development, maturation, and carcinogenesis. It is now apparent that estrogens, both those synthesized by the body as well as those from our environment, also target the prostate during all stages of development. Little is known about the mechanisms involved in estrogen stimulation of carcinogenesis and less is known about how to prevent or treat prostate cancer through estrogenic pathways. To better understand how estrogens mediate their carcinogenic effects, the respective roles of estrogen receptor (ER)-alpha and ER-beta must be elucidated in the epithelial and stromal cells that constitute the prostate. Lastly, the significance of ER signaling during various ontogenic periods must be determined. Answers to these questions will further our understanding of the mechanisms of estrogen/ER signaling and will serve as a basis for chemopreventive and/or chemotherapeutic strategies for prostate cancer.

Cancer statistics, 2007

Each year, the American Cancer Society (ACS) estimates the number of new cancer cases and deaths expected in the United States in the current year and compiles the most recent data on cancer incidence, mortality, and survival based on incidence data from the National Cancer Institute, Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries and mortality data from the National Center for Health Statistics. This report considers incidence data through 2003 and mortality data through 2004. Incidence and death rates are age-standardized to the 2000 US standard million population. A total of 1,444,920 new cancer cases and 559,650 deaths for cancers are projected to occur in the United States in 2007. Notable trends in cancer incidence and mortality rates include stabilization of the age-standardized, delay-adjusted incidence rates for all cancers combined in men from 1995 through 2003; a continuing increase in the incidence rate by 0.3% per year in women; and a 13.6% total decrease in age-standardized cancer death rates among men and women combined between 1991 and 2004. This report also examines cancer incidence, mortality, and survival by site, sex, race/ethnicity, geographic area, and calendar year, as well as the proportionate contribution of selected sites to the overall trends. While the absolute number of cancer deaths decreased for the second consecutive year in the United States (by more than 3,000 from 2003 to 2004) and much progress has been made in reducing mortality rates and improving survival, cancer still accounts for more deaths than heart disease in persons under age 85 years. Further progress can be accelerated by supporting new discoveries and by applying existing cancer control knowledge across all segments of the population.

Integration of Rapid Signaling Events with Steroid Hormone Receptor Action in Breast and Prostate Cancer

Steroid hormone receptors (SRs) are ligand-activated transcription factors and sensors for growth factor-initiated signaling pathways in hormonally regulated tissues, such as the breast or prostate. Recent discoveries suggest that several protein kinases are rapidly activated in response to steroid hormone binding to cytoplasmic SRs. Induction of rapid signaling upon SR ligand binding ensures that receptors and coregulators are appropriately phosphorylated as part of optimal transcription complexes. Alternatively, SR-activated kinase cascades provide additional avenues for SR-regulated gene expression independent of SR nuclear action. We provide an overview of SR and signaling cross talk in breast and prostate cancers, using the human progesterone receptor (PR) and androgen receptor (AR) as models. Kinases are emerging as key mediators of SR action. Cross talk between SR and membrane-initiated signaling events suggests a mechanism for coordinate regulation of gene subsets by mitogenic stimuli in hormonally responsive normal tissues; such cross talk is suspected to contribute to cancer biology.

Targeting factors involved in bone remodeling as treatment strategies in prostate cancer bone metastasis

Prostate cancer is the most commonly diagnosed cancer in men within the western world and the third leading cause of cancer-related deaths. Even if the cancer is considered localized to the prostate, there is a 15% to 20% incidence of subsequent metastatic disease. Prostate cancer has a very high proclivity for metastasizing to bone, with approximately 90% of men with advanced disease having skeletal lesions. The prostate cancer metastases are characteristically osteoblastic, with extensive new bone deposition, unlike other tumors that metastasize to bone and cause an osteolytic response reflective of bone degradation. There are a considerable number of studies relating to inhibition of the osteoblastic response, including interference with endothelin-1, bone morphogenetic proteins, and Wnt signaling pathways. Within the past few years, several studies showed that increased osteolytic activity also occurs in the background of the prostate cancer skeletal metastases. Because growth factors are being released from the bone matrix during degradation, it suggests that inhibition of osteolysis might be effective in slowing tumor growth. Several strategies are being developed and applied to affect directly the osteolytic events, including use of bisphosphonates and targeting the critical biological regulators of osteoclastogenesis, receptor activator of nuclear factor-kappaB and receptor activator of nuclear factor-kappaB ligand. This review focuses on several of the clinical and preclinical strategies to inhibit the growth of prostate cancer cells in bone and to alleviate the multitude of associated skeletal-related events.

Three-color FISH analysis of TMPRSS2/ERG fusions in prostate cancer indicates that genomic microdeletion of chromosome 21 is associated with rearrangement

The recent description of novel recurrent gene fusions in approximately 80% of prostate cancer (PCa) cases has generated increased interest in the search for new translocations in other epithelial cancers and emphasizes the importance of understanding the origins and biologic implications of these genomic rearrangements. Analysis of 15 PCa cases by reverse transcription-polymerase chain reaction was used to detect six ERG-related gene fusion transcripts with TMPRSS2. No TMPRSS2/ETV1 chimeric fusion was detected in this series. Three-color fluorescence in situ hybridization confirms that TMPRSS2/ERG fusion may be accompanied by a small hemizygous sequence deletion on chromosome 21 between ERG and TMPRSS2 genes. Analysis of genomic architecture in the region of genomic rearrangement suggests that tracts of microhomology could facilitate TMPRSS2/ERG fusion events.

Growth factor signalling in prostatic growth: significance in tumour development and therapeutic targeting

The intricate balance maintained between cell growth and proliferation factors and apoptosis-inducing factors is fundamental to the regulation of prostate growth. Disruptions in this homeostasis often trigger the loss of apoptosis and the over-expression of factors promoting cell survival and proliferation, inevitably leading to tumorigenesis and cancer. Deregulation of prostate growth during prostate cancer development and progression is characterized by apoptotic evasion, uncontrolled proliferation, and increased invasive potential. Thus, in advanced stages of disease progression, surviving prostate tumour cells acquire the ability to migrate and invade heterotopic tissues, with the bone and lymph nodes being the most common sites for human prostate cancer metastasis. The challenges in the implementation of effective therapeutic strategies for the treatment of advanced metastatic prostate cancer reflect the multidimensional nature and functional significance of antiapoptotic pathways in the emergence of therapeutic resistance of prostate tumours. In this chapter, we discuss the current understanding of the molecular mechanisms governing growth factor signalling pathways with often overlapping functions that contribute to loss of apoptosis control and activation of cell proliferation towards aggressive prostate tumorigenic growth and metastatic behaviour. While a full understanding of the prosurvival characteristics of these growth factor pathways is still evolving, the impact that growth factors such a epidermal growth factor and transforming growth factor-beta can be recognized by the vigorous attempts at therapeutic targeting of their key signalling steps.

Quinazoline α1-Blockers: Are there any News about their Efficacy in Inhibiting Prostate Tumor Growth?

α1-adrenoceptor agonists have recently been recognized as growth factors for several cell types, including both stromal smooth muscle- and epithelial cells of the prostate gland, by triggering off a cascade of intracellular signal transduction pathway that controls cell proliferation. On the contrary, quinazoline α1 -blockers (doxazosin, terazosin, prazosin) inhibit cell kinetics and induce, above all, anoikis and apoptotic death of both stromal smooth muscle- and epithelial cells, through α1 -adrenoceptor-indipendent mechanisms, thus preventing or delaying prostate tumor growth.