Amplification and overexpression of vinculin are associated with increased tumour cell proliferation and progression in advanced prostate cancer

The Potential of Extracellular Matrix- and Integrin Adhesion Complex-Related Molecules for Prostate Cancer Biomarker Discovery

Prostate cancer is among the top five cancer types according to incidence and mortality. One of the main obstacles in prostate cancer management is the inability to foresee its course, which ranges from slow growth throughout years that requires minimum or no intervention to highly aggressive disease that spreads quickly and resists treatment. Therefore, it is not surprising that numerous studies have attempted to find biomarkers of prostate cancer occurrence, risk stratification, therapy response, and patient outcome. However, only a few prostate cancer biomarkers are used in clinics, which shows how difficult it is to find a novel biomarker. Cell adhesion to the extracellular matrix (ECM) through integrins is among the essential processes that govern its fate. Upon activation and ligation, integrins form multi-protein intracellular structures called integrin adhesion complexes (IACs). In this review article, the focus is put on the biomarker potential of the ECM- and IAC-related molecules stemming from both body fluids and prostate cancer tissue. The processes that they are involved in, such as tumor stiffening, bone turnover, and communication via exosomes, and their biomarker potential are also reviewed.

Focal adhesion signaling pathway involved in skin immune response of tongue sole Cynoglossus semilaevis to Vibrio vulnificus infection

Focal adhesion (FA) plays a key role in cell adhesion, migration and antibacterial immune, but it remained unclear in fish. In this study, half-smooth tongue sole Cynoglossus semilaevis were infected with Vibrio vulnificus, and then immune-related protein in the skin, especially for FA signaling pathway were screened and identified by iTRAQ analysis. Results showed that the differentially expressed proteins (DEPs) in skin immune response (eg., ITGA6, FN, COCH, AMBP, COL6A1, COL6A3, COL6A6, LAMB1, LAMC1, FLMNA) were firstly found in FA signaling pathway. Furthermore, the validation analysis of FA-related genes were basically consistent with the iTRAQ data at 36 hpi (r = 0.678, p < 0.01), and their spatio-temporal expressions were confirmed by qPCR analysis. The molecular characterization of vinculin of C. semilaevis was described. This study will provide a new perspective for understanding the molecular mechanism of FA signaling pathway in the skin immune response in marine fish.

Cervical cancer-derived exosomal miR-663b promotes angiogenesis by inhibiting vinculin expression in vascular endothelial cells

BACKGROUND

Angiogenesis provides essential nutrients and oxygen for tumor growth and has become the main mechanism of tumor invasion and metastasis. Exosomes are nanoscale membrane vesicles containing proteins, lipids, mRNA and microRNA (miRNA), which mediate intercellular communication and play an important role in tumor progression. Accumulated evidence indicates that tumor-derived exosomal miRNAs participate in the tumor microenvironment and promote angiogenesis.

METHODS

Bioinformatic target prediction and dual luciferase reporter assays were performed to identify the binding site between miR-663b and the 3'-UTR of vinculin (VCL). VCL overexpression lentivirus and miR-663b overexpression/inhibition lentivirus were used to create a VCL overexpression model and miR-663b overexpression/inhibition model in-vitro. Immunohistochemistry (IHC) assays and western blot assays were used to detect protein expression. Exosome-cell cocultures, wound healing assays, tube formation assays and transwell assays were used to measure the migration and tube formation ability of vascular endothelial cells [human umbilical vein endothelial cells (HUVECs)]. siRNA targeted VCL was used to knockdown VCL.

RESULTS

In the present study, we found that miR-663b was elevated in cervical cancer tissue and exosomes. miR-663b could bind the 3'-UTR of VCL and inhibit its expression. VCL is downregulated in cervical cancer, and decreased VCL has a negative correlation with a high level of miR-663b. Further studies demonstrated that exosomes secreted by cervical cancer cells can deliver miR-663b to HUVECs and inhibit the expression of VCL, thereby promoting angiogenesis and tumor growth.

CONCLUSIONS

miR-663b derived from cancer cell exosomes acts as a driving factor for angiogenesis and a potential target of antiangiogenic therapy in cervical cancer. Our findings illustrated a new signaling pathway, including exosomes, miRNAs and target genes, which provides potential targets for antiangiogenic therapy.

Patterns of stemness-associated markers in the development of castration-resistant prostate cancer

BACKGROUND

Putative castration-resistant (CR) stem-like cells (CRSC) have been identified based on their ability to initiate and drive prostate cancer (PCa) recurrence following castration in vivo. Yet the relevance of these CRSC in the course of the human disease and particularly for the transition from hormone-naive (HN) to castration-resistance is unclear. In this study, we aimed at deciphering the significance of CRSC markers in PCa progression.

METHODS

We constructed a tissue microarray comprising 112 matched HN and CR tissue specimens derived from 55 PCa patients. Expression of eight stemness-associated markers (ALDH1A1, ALDH1A3, ALDH3A1, BMI1, NANOG, NKX3.1, OCT4, SOX2) was assessed by immunohistochemistry and scored as a percentage of positive tumor cells. For each marker, the resulting scores were statistically analyzed and compared to pathological and clinical data associated with the samples. Unsupervised clustering analysis was performed to stratify patients according to the expression of the eight CRSC markers. Publicly-available transcriptional datasets comprising HN and CR PCa samples were interrogated to assess the expression of the factors in silico.

RESULTS

Immunohistochemical assessment of paired samples revealed atypical patterns of expression and intra- and intertumor heterogeneity for a subset of CRSC markers. While the expression of particular CRSC markers was dynamic over time in some patients, none of the markers showed significant changes in expression upon the development of castration resistance (CR vs HN). Using unsupervised clustering approaches, we identified phenotypic subtypes based on the expression of specific stem-associated markers. In particular, we found (a) patterns of mutual exclusivity for ALDH1A1 and ALDH1A3 expression, which was also observed at the transcriptomic level in publicly-available PCa datasets, and (b) a phenotypic cluster associated with more aggressive features. Finally, by comparing HN and CR matched samples, we identified phenotypic cluster switches (ie, change of phenotypic cluster between the HN and CR state), that may be associated with clinical and predictive relevance.

CONCLUSIONS

Our findings indicate stemness-associated patterns that are associated with the development of castration-resistance. These results pave the way toward a deeper understanding of the relevance of CRSC markers in PCa progression and resistance to androgen-deprivation therapy.

Vinculin presents unfavorable prediction in ovarian cancer and prevents proliferation and migration of ovarian cancer cells

The influences of Vinculin on many cancers were blurry, including ovarian cancer. Thus, we concentrated on the efficient role of Vinculin in ovarian cancer and explored the potential mechanism(s). Expression of Vinculin in ovarian cancer tissues and cell lines was investigated by real-time polymerase chain reaction, immunohistochemistry, and Western blot. The Kaplan-Meier manner with the logrank was performed to assess overall survival. We further evaluated the relations between Vinculin expression and clinicopathological features of ovarian cancer. Moreover, Vinculin was overexpressed or silenced by respectively transfection with pcDNA-Vinculin or small interfering (si-Vinculin) into human ovarian cancer cell line Caov3 or human ovarian epithelial cell line (HOEpiC). Thereafter, cell viability, cell apoptosis, and migration were checked by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide, flow cytometer, and scratch assay, respectively. Likewise, the apoptosis- and migration-related proteins were distinguished by Western blot. Compared to the nontumor tissues or HOEpiC cells, Vinculin was significantly lower expressed in the ovarian cancer tissues and cells. Furthermore, we found out that Vinculin was primarily distributed at the cell membrane and cytoplasm. Moreover, Vinculin was negatively associated with International Federation of Gynecology and Obstetrics stage, grade, and distant metastasis. Overexpression of Vinculin dramatically weakened cell viability and migration and stimulated apoptosis. Conversely, suppression of Vinculin showed opposite results. Vinculin presents unfavorable prediction in ovarian cancer and inhibits ovarian cancer proliferation and migration.

Xenograft-derived mRNA/miR and protein interaction networks of systemic dissemination in human prostate cancer

BACKGROUND

Distant metastasis formation is the major clinical problem in prostate cancer (PCa) and the underlying mechanisms remain poorly understood. Our aim was to identify novel molecules that functionally contribute to human PCa systemic dissemination based on unbiased approaches.

METHODS

We compared mRNA, microRNA (miR) and protein expression levels in established human PCa xenograft tumours with high (PC-3), moderate (VCaP) or weak (DU-145) spontaneous micrometastatic potential. By focussing on those mRNAs, miRs and proteins that were differentially regulated among the xenograft groups and known to interact with each other we constructed dissemination-related mRNA/miR and protein/miR networks. Next, we clinically and functionally validated our findings.

RESULTS

Besides known determinants of PCa progression and/or metastasis, our interaction networks include several novel candidates. We observed a clear role of epithelial-to-mesenchymal transition (EMT) pathways for PCa dissemination, which was additionally confirmed by an independent human PCa model (ARCAP-E/-M). Two converging nodes, CD46 (decreasing with metastatic potential) and DDX21 (increasing with metastatic potential), were used to test the clinical relevance of the networks. Intriguingly, both network nodes consistently added prognostic information for patients with PCa whereas CD46 loss predicted poor outcome independent of established parameters. Accordingly, depletion of CD46 in weakly metastatic PCa cells induced EMT-like properties in vitro and spontaneous micrometastasis formation in vivo.

CONCLUSIONS

The clinical and functional relevance of the dissemination-related interaction networks shown here could be successfully validated by proof-of-principle experiments. Therefore, we suggest a direct pro-metastatic, clinically relevant role for the multiple novel candidates included in this study; these should be further exploited by future studies.

Vinculin promotes gastric cancer proliferation and migration and predicts poor prognosis in patients with gastric cancer

Vinculin is a highly conserved protein involved in cell proliferation, migration, and adhesion. However, the effects of vinculin on gastric cancer (GC) remain unclear. Therefore, we aimed to explore the functional role of vinculin in GC, as well as its underlying mechanism. Expression of vinculin in patients with GC was analyzed by real-time polymerase chain reaction, Western blot analysis, and immunohistochemistry. Overall survival was evaluated by the Kaplan-Meier method with the log-rank test. The relationship between vinculin and clinicopathological characteristics of patients with GC was further identified. In addition, we assessed the expression of vinculin in GC cell lines. Besides, vinculin was suppressed or overexpressed by transfection with small interfering (si-vinculin) or pcDNA-vinculin and then cell viability, cell apoptosis, and/or migration was respectively examined by the 3-(4, 5-dimethylthiazole-2-yl)-2, 5-biphenyl tetrazolium bromide assay, flow cytometer, and scratch assay, respectively. Moreover, the cell cycle- and apoptosis-related proteins were detected by Western blot analysis. The expression of vinculin was significantly increased in the GC tissues and cells compared with the nontumor tissues or cells. Vinculin protein positive staining was mainly located in the cell membrane and cytoplasm. Moreover, vinculin was significantly associated with Tumor Node Metastasis (TNM) and poor differentiation. Patients with high vinculin levels had significantly worse overall survival than those with low levels. Suppression of vinculin significantly decreased cell viability and migration and promoted cell apoptosis. However, overexpression of vinculin statistically increased cell viability but had no effects on cell apoptosis. Vinculin promotes GC proliferation and migration and predicts poor prognosis in patients with GC.

Connexins, important players in the dissemination of prostate cancer cells

Over the past 50years, increasing experimental evidences have established that connexins (Cxs) and gap junctional intercellular communication (GJIC) ensure an important role in both the onset and development of cancerous processes. In the present review, we focus on the impact of Cxs and GJIC during the development of prostate cancer (PCa), from the primary growth mainly localized in acinar glands and ducts to the distant metastasis mainly concentrated in bone. As observed in several other types of solid tumours, Cxs and especially Cx43 exhibit an ambivalent role with a tumour suppressor effect in the early stages and, conversely, a rather pro-tumoural profile for most of invasion and dissemination steps to secondary sites. We report here the current knowledge on the function of Cxs during PCa cells migration, cytoskeletal dynamics, proteinases activities and the cross talk with the surrounding stromal cells in the microenvironment of the tumour and the bones. In addition, we discuss the role of Cxs in the bone tropism even if the prostate model is rarely used to study the complete sequence of cancer dissemination compared to breast cancer or melanoma. Even if not yet fully understood, these recent findings on Cxs provide new insights into their molecular mechanisms associated with progression and bone targeted behaviour of PCa. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.

Vinculin promotes nuclear localization of TAZ to inhibit ECM stiffness-dependent differentiation into adipocytes

Extracellular matrix (ECM) stiffness regulates the lineage commitment of mesenchymal stem cells (MSCs). Although cells sense ECM stiffness through focal adhesions, how cells sense ECM stiffness and regulate ECM stiffness-dependent differentiation remains largely unclear. In this study, we show that the cytoskeletal focal adhesion protein vinculin plays a critical role in the ECM stiffness-dependent adipocyte differentiation of MSCs. ST2 mouse MSCs differentiate into adipocytes and osteoblasts in an ECM stiffness-dependent manner. We find that a rigid ECM increases the amount of cytoskeleton-associated vinculin and promotes the nuclear localization and activity of the transcriptional coactivator paralogs Yes-associated protein (YAP, also known as YAP1) and transcriptional coactivator with a PDZ-binding motif (TAZ, also known as WWTR1) (hereafter YAP/TAZ). Vinculin is necessary for enhanced nuclear localization and activity of YAP/TAZ on the rigid ECM but it does not affect the phosphorylation of the YAP/TAZ kinase LATS1. Furthermore, vinculin depletion promotes differentiation into adipocytes on rigid ECM, while it inhibits differentiation into osteoblasts. Finally, TAZ knockdown was less effective at promoting adipocyte differentiation in vinculin-depleted cells than in control cells. These results suggest that vinculin promotes the nuclear localization of transcription factor TAZ to inhibit the adipocyte differentiation on rigid ECM.

Celecoxib exhibits an anti-gastric cancer effect by targeting focal adhesion and leukocyte transendothelial migration-associated genes

Gastric cancer (GC) is a prevalent cancer, which remains incurable, and therefore requires an alternative treatment method. Celecoxib is a nonsteroidal anti-inflammatory drug that targets cyclooxygenase-2, and exhibits anticancer effects. The present study aimed to investigate the anti-GC mechanism of celecoxib using bioinformatics methods. Gene expression datasets GSE56807 (GC tissues and normal gastric tissues) and GSE54657 (celecoxib-treated and non-treated human GC epithelial AGS cells) were downloaded from the Gene Expression Omnibus database. Two groups of differentially expressed genes (DEGs) were identified using limma package in R language. The criterion for GSE56807 was a false discovery rate of <0.05, while that for GSE54657 was P<0.01. Overlapping DEGs from the two datasets were screened out. Subsequently, pathway enrichment analysis was performed using Database for Annotation, Visualization and Integrated Discovery software (P<0.1; gene count ≥2). In addition, the protein-protein interactions (PPIs) among the overlapped DEGs were obtained based on IntAct, Database of Interacting Proteins, Biomolecular Interaction Network Database and Human Protein Reference Database. Finally, a PPI network was visualized using Cytoscape software. A total of 137 overlapped DEGs were obtained, and DEGs with opposite regulation directions in the two datasets were significantly enriched in focal adhesion and leukocyte transendothelial migration. Subsequently, a PPI network of overlapped DEGs was constructed. Comprehensively, a total of 8 key DEGs [cysteine and glycine rich protein 1 (CSRP1), thrombospondin 1 (THBS1), myosin light chain 9 (MYL9), filamin A (FLNA), actinin alpha 1 (ACTN1), vinculin (VCL), laminin subunit gamma 2 (LAMC2) and claudin 1 (CLDN1)] were upregulated in GC tissues and downregulated in celecoxib-treated cells. In conclusion, celecoxib may exhibit anti-GC effects by suppressing the expression of CSRP1, THBS1, MYL9, FLNA, ACTN1, VCL, LAMC2 and CLDN1, and inhibiting leukocyte transendothelial migration and focal adhesion. However, relevant experiments are required to confirm the conclusion of the present study.

Bioinformatics analysis of differentially expressed proteins in prostate cancer based on proteomics data

We mined the literature for proteomics data to examine the occurrence and metastasis of prostate cancer (PCa) through a bioinformatics analysis. We divided the differentially expressed proteins (DEPs) into two groups: the group consisting of PCa and benign tissues (P&b) and the group presenting both high and low PCa metastatic tendencies (H&L). In the P&b group, we found 320 DEPs, 20 of which were reported more than three times, and DES was the most commonly reported. Among these DEPs, the expression levels of FGG, GSN, SERPINC1, TPM1, and TUBB4B have not yet been correlated with PCa. In the H&L group, we identified 353 DEPs, 13 of which were reported more than three times. Among these DEPs, MDH2 and MYH9 have not yet been correlated with PCa metastasis. We further confirmed that DES was differentially expressed between 30 cancer and 30 benign tissues. In addition, DEPs associated with protein transport, regulation of actin cytoskeleton, and the extracellular matrix (ECM)–receptor interaction pathway were prevalent in the H&L group and have not yet been studied in detail in this context. Proteins related to homeostasis, the wound-healing response, focal adhesions, and the complement and coagulation pathways were overrepresented in both groups. Our findings suggest that the repeatedly reported DEPs in the two groups may function as potential biomarkers for detecting PCa and predicting its aggressiveness. Furthermore, the implicated biological processes and signaling pathways may help elucidate the molecular mechanisms of PCa carcinogenesis and metastasis and provide new targets for clinical treatment.

Gene interference strategies as a new tool for the treatment of prostate cancer

Prostate cancer (PCa) is one of the most common cancer in men. It affects older men and the incidence increases with age; the median age at diagnosis is 67 years. The diagnosis of PCa is essentially based on three tools: digital rectal exam, serum concentration of prostate specific antigen, and transrectal ultrasound-guided biopsy. Currently, the therapeutic treatments of this cancer are different and range from the prostatectomy to hormonal therapy, to radiation therapy, to immunotherapy, and to chemotherapy. However, additional efforts are required in order to find new weapons for the treatment of metastatic setting of disease. The purpose of this review is to highlight new therapeutic strategies based on gene interference; in fact, numerous siRNA and miRNA in the therapeutic treatment of PCa are reported below.

Integrin β4 and vinculin contained in exosomes are potential markers for progression of prostate cancer associated with taxane-resistance

Treatment with taxanes for castration-resistant prostate cancer often leads to the development of resistance. It has been recently demonstrated that exosomes present in the body fluids contain proteins and RNAs in the cells from which they are derived and could serve as a diagnostic marker for various diseases. In the present study, we aimed to identify proteins contained in exosomes that could be markers for progression and taxane-resistance of prostate cancer. Exosomes were isolated by differential centrifugation from the culture medium of taxane-resistant human prostate cancer PC-3 cells (PC-3R) and their parental PC-3 cells. Isolated exosomes were subjected to iTRAQ-based quantitative proteomic analysis. Exosomes were also isolated from the culture medium by using anti-CD9 antibody-conjugated magnetic beads. Protein expression was knocked down by siRNA transfection followed by analysis of the silencing effects. Proteomic analysis showed that integrin β4 (ITGB4) and vinculin (VCL) were upregulated in exosomes derived from PC-3R cells compared to PC-3 cells. The elevation of ITGB4 and VCL was confirmed in exosomes captured by anti-CD9 antibody from the culture medium of PC-3R cells. Silencing of ITGB4 and VCL expression did not affect proliferation and taxane-resistance of PC-3R cells, but ITGB4 knockdown attenuated both cell migration and invasion and VCL knockdown reduced invasion. Our results suggest that ITGB4 and VCL in exosomes could be useful markers for progression of prostate cancer associated with taxane-resistance, providing the basis for development of an exosome-based diagnostic system.

Identification and validation of potential new biomarkers for prostate cancer diagnosis and prognosis using 2D-DIGE and MS

This study was designed to identify and validate potential new biomarkers for prostate cancer and to distinguish patients with and without biochemical relapse. Prostate tissue samples analyzed by 2D-DIGE (two-dimensional difference in gel electrophoresis) and mass spectrometry (MS) revealed downregulation of secernin-1 (P < 0.044) in prostate cancer, while vinculin showed significant upregulation (P < 0.001). Secernin-1 overexpression in prostate tissue was validated using Western blot and immunohistochemistry while vinculin expression was validated using immunohistochemistry. These findings indicate that secernin-1 and vinculin are potential new tissue biomarkers for prostate cancer diagnosis and prognosis, respectively. For validation, protein levels in urine were also examined by Western blot analysis. Urinary vinculin levels in prostate cancer patients were significantly higher than in urine from nontumor patients (P = 0.006). Using multiple reaction monitoring-MS (MRM-MS) analysis, prostatic acid phosphatase (PAP) showed significant higher levels in the urine of prostate cancer patients compared to controls (P = 0.012), while galectin-3 showed significant lower levels in the urine of prostate cancer patients with biochemical relapse, compared to those without relapse (P = 0.017). Three proteins were successfully differentiated between patients with and without prostate cancer and patients with and without relapse by using MRM. Thus, this technique shows promise for implementation as a noninvasive clinical diagnostic technique.

The role of phosphoinositide-regulated actin reorganization in chemotaxis and cell migration

Reorganization of the actin cytoskeleton is essential for cell motility and chemotaxis. Actin-binding proteins (ABPs) and membrane lipids, especially phosphoinositides PI(4,5)P2 and PI(3,4,5)P3 are involved in the regulation of this reorganization. At least 15 ABPs have been reported to interact with, or regulated by phosphoinositides (PIPs) whose synthesis is regulated by extracellular signals. Recent studies have uncovered several parallel intracellular signalling pathways that crosstalk in chemotaxing cells. Here, we review the roles of ABPs and phosphoinositides in chemotaxis and cell migration.

LINKED ARTICLES

This article is part of a themed section on Cytoskeleton, Extracellular Matrix, Cell Migration, Wound Healing and Related Topics. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-24.

Intracellular modifiers of integrin alpha 6p production in aggressive prostate and breast cancer cell lines

Cancer metastasis is a multi-step process in which tumor cells gain the ability to invade beyond the primary tumor and colonize distant sites. The mechanisms regulating the metastatic process confer changes to cell adhesion receptors including the integrin family of receptors. Our group previously discovered that the α6 integrin (ITGA6/CD49f) is post translationally modified by urokinase plasminogen activator (uPA) and its receptor, urokinase plasminogen activator receptor (uPAR), to form the variant ITGA6p. This variant of ITGA6 is a cleaved form of the receptor that lacks the ligand-binding domain. Although it is established that the uPA/uPAR axis drives ITGA6 cleavage, the mechanisms regulating cleavage have not been defined. Intracellular integrin dependent "inside-out" signaling is a major regulator of integrin function and the uPA/uPAR axis. We hypothesized that intracellular signaling molecules play a role in formation of ITGA6p to promote cell migration during cancer metastasis. In order to test our hypothesis, DU145 and PC3B1 prostate cancer and MDA-MB-231 breast cancer cell lines were treated with small interfering RNA targeting actin and the intracellular signaling regulators focal adhesion kinase (FAK), integrin linked kinase (ILK), and paxillin. The results demonstrated that inhibition of actin, FAK, and ILK expression resulted in significantly increased uPAR expression and ITGA6p production. Inhibition of actin increased ITGA6p, although inhibition of paxillin did not affect ITGA6p formation. Taken together, these results suggest that FAK and ILK dependent "inside-out" signaling, and actin dynamics regulate extracellular production of ITGA6p and the aggressive phenotype.

Chemical proteomics identifies heterogeneous nuclear ribonucleoprotein (hnRNP) A1 as the molecular target of quercetin in its anti-cancer effects in PC-3 cells

Quercetin, a flavonoid abundantly present in plants, is widely used as a phytotherapy in prostatitis and prostate cancer. Although quercetin has been reported to have a number of therapeutic effects, the cellular target(s) responsible for its anti-cancer action has not yet been clearly elucidated. Here, employing affinity chromatography and mass spectrometry, we identified heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) as a direct target of quercetin. A specific interaction between quercetin and hnRNPA1 was validated by immunoblotting and in vitro binding experiments. We found that quercetin bound the C-terminal region of hnRNPA1, impairing the ability of hnRNPA1 to shuttle between the nucleus and cytoplasm and ultimately resulting in its cytoplasmic retention. In addition, hnRNPA1 was recruited to stress granules after treatment of cells with quercetin for up to 48 h, and the levels of cIAP1 (cellular inhibitor of apoptosis), an internal ribosome entry site translation-dependent protein, were reduced by hnRNPA1 regulation. This is the first report that anti-cancer effects of quercetin are mediated, in part, by impairing functions of hnRNPA1, insights that were obtained using a chemical proteomics strategy.

GM-CSF Production by Tumor Cells Is Associated with Improved Survival in Colorectal Cancer

PURPOSE

Colorectal cancer infiltration by CD16(+) myeloid cells correlates with improved prognosis. We addressed mechanistic clues and gene and protein expression of cytokines potentially associated with macrophage polarization.

EXPERIMENTAL DESIGN

GM-CSF or M-CSF-stimulated peripheral blood CD14(+) cells from healthy donors were cocultured with colorectal cancer cells. Tumor cell proliferation was assessed by (3)H-thymidine incorporation. Expression of cytokine genes in colorectal cancer and autologous healthy mucosa was tested by quantitative, real-time PCR. A tumor microarray (TMA) including >1,200 colorectal cancer specimens was stained with GM-CSF- and M-CSF-specific antibodies. Clinicopathological features and overall survival were analyzed.

RESULTS

GM-CSF induced CD16 expression in 66% ± 8% of monocytes, as compared with 28% ± 1% in cells stimulated by M-CSF (P = 0.011). GM-CSF but not M-CSF-stimulated macrophages significantly (P < 0.02) inhibited colorectal cancer cell proliferation. GM-CSF gene was expressed to significantly (n = 45, P < 0.0001) higher extents in colorectal cancer than in healthy mucosa, whereas M-CSF gene expression was similar in healthy mucosa and colorectal cancer. Accordingly, IL1β and IL23 genes, typically expressed by M1 macrophages, were expressed to significantly (P < 0.001) higher extents in colorectal cancer than in healthy mucosa. TMA staining revealed that GM-CSF production by tumor cells is associated with lower T stage (P = 0.02), "pushing" growth pattern (P = 0.004) and significantly (P = 0.0002) longer survival in mismatch-repair proficient colorectal cancer. Favorable prognostic effect of GM-CSF production by colorectal cancer cells was confirmed by multivariate analysis and was independent from CD16(+) and CD8(+) cell colorectal cancer infiltration. M-CSF expression had no significant prognostic relevance.

CONCLUSIONS

GM-CSF production by tumor cells is an independent favorable prognostic factor in colorectal cancer.

Molecular pathology of prostate cancer revealed by next-generation sequencing: opportunities for genome-based personalized therapy

PURPOSE OF REVIEW

This article reviews recently identified genomic mutations in prostate cancer.

RECENT FINDINGS

Advanced sequencing technologies have made it possible to obtain large amounts of data on genomes and transcriptomes of cancers. Such technologies have been used to sequence prostate cancer of different stages, from treatment-naive cancers, to advanced, castration-resistant cancers to the aggressive small cell neuroendocrine carcinomas. For each category of prostate cancer, distinct and overlapping DNA sequence alterations were discovered, including point mutations, small insertions or deletions, copy number changes and chromosomal rearrangements. There appears to be a stepwise increase in genomic alterations from low risk to high risk to advanced cancers.

SUMMARY

These novel findings have significantly increased our knowledge of the genetic basis of human prostate cancer and the molecular mechanisms responsible for disease progression and treatment resistance. Some of the lesions are potential therapeutic targets. Studies along this direction will eventually make it possible to design personalized management plans for individual patients.

Characterization and clinical relevance of ALDHbright populations in prostate cancer

PURPOSE

High aldehyde dehydrogenase (ALDH) has been suggested to selectively mark cells with high tumorigenic potential in established prostate cancer cell lines. However, the existence of cells with high ALDH activity (ALDH(bright)) in primary prostate cancer specimens has not been shown so far. We investigated the presence, phenotype, and clinical significance of ALDH(bright) populations in clinical prostate cancer specimens.

EXPERIMENTAL DESIGN

We used ALDEFLUOR technology and fluorescence-activated cell-sorting (FACS) staining to identify and characterize ALDH(bright) populations in cells freshly isolated from clinical prostate cancer specimens. Expression of genes encoding ALDH-specific isoforms was evaluated by quantitative real-time PCR in normal prostate, benign prostatic hyperplasia (BPH), and prostate cancer tissues. ALDH1A1-specific expression and prognostic significance were assessed by staining two tissue microarrays that included more than 500 samples of BPH, prostatic intraepithelial neoplasia (PIN), and multistage prostate cancer.

RESULTS

ALDH(bright) cells were detectable in freshly excised prostate cancer specimens (n = 39) and were mainly included within the EpCAM((+)) and Trop2((+)) cell populations. Although several ALDH isoforms were expressed to high extents in prostate cancer, only ALDH1A1 gene expression significantly correlated with ALDH activity (P < 0.01) and was increased in cancers with high Gleason scores (P = 0.03). Most importantly, ALDH1A1 protein was expressed significantly more frequently and at higher levels in advanced-stage than in low-stage prostate cancer and BPH. Notably, ALDH1A1 positivity was associated with poor survival (P = 0.02) in hormone-naïve patients.

CONCLUSIONS

Our data indicate that ALDH contributes to the identification of subsets of prostate cancer cells of potentially high clinical relevance.

Estrogen receptor β expression and androgen receptor phosphorylation correlate with a poor clinical outcome in hormone-naive prostate cancer and are elevated in castration-resistant disease

Patients with advanced prostate cancer (PC) are usually treated with androgen withdrawal. While this therapy is initially effective, nearly all PCs become refractory to it. As hormone receptors play a crucial role in this process, we constructed a tissue microarray consisting of PC samples from 107 hormone-naïve (HN) and 101 castration-resistant (CR) PC patients and analyzed the androgen receptor (AR) gene copy number and the protein expression profiles of AR, Serin210-phosphorylated AR (pAR(210)), estrogen receptor (ER)β, ERα and the proliferation marker Ki67. The amplification of the AR gene was virtually restricted to CR PC and was significantly associated with increased AR protein expression (P<0.0001) and higher tumor cell proliferation (P=0.001). Strong AR expression was observed in a subgroup of HN PC patients with an adverse prognosis. In contrast, the absence of AR expression in CR PC was significantly associated with a poor overall survival. While pAR(210) was predominantly found in CR PC patients (P<0.0001), pAR(210) positivity was observed in a subgroup of HN PC patients with a poor survival (P<0.05). Epithelial ERα expression was restricted to CR PC cells (9%). ERβ protein expression was found in 38% of both HN and CR PCs, but was elevated in matched CR PC specimens. Similar to pAR(210), the presence of ERβ in HN patients was significantly associated with an adverse prognosis (P<0.005). Our results strongly suggest a major role for pAR(210) and ERβ in HN PC. The expression of these markers might be directly involved in CR tumor growth.

Sequencing the transcriptional network of androgen receptor in prostate cancer

The progression of prostate cancer is largely dependent on the activity of the androgen receptor (AR), which in turn, correlates with the net output of the AR transcriptional regulatory network. A detailed and thorough understanding of the AR transcriptional regulatory network is therefore critical in the strategic manipulation of AR activity for the targeted eradication of prostate cancer cells. In this mini-review, we highlight some of the novel and unexpected mechanistic and functional insights of the AR transcriptional network derived from recent targeted sequencing (ChIP-Seq) studies of AR and its coregulatory factors in prostate cancer cells.

High NRBP1 expression in prostate cancer is linked with poor clinical outcomes and increased cancer cell growth

BACKGROUND

We recently established the rationale that NRBP1 (nuclear receptor binding protein 1) has a potential growth-promoting role in cell biology. NRBP1 interacts directly with TSC-22, a potential tumor suppressor gene that is differently expressed in prostate cancer. Consequently, we analyzed the role of NRBP1 expression in prostate cancer cell lines and its expression on prostate cancer tissue microarrays (TMA).

METHODS

The effect of NRBP1 expression on tumor cell growth was analyzed by using RNAi. NRBP1 protein expression was evaluated on two TMAs containing prostate samples from more than 1,000 patients. Associations with clinico-pathological features, the proliferation marker Ki67 and survival data were analyzed.

RESULTS

RNAi mediated silencing of NRBP1 expression in prostate cancer cell lines resulted in reduced cell growth (P < 0.05). TMA analysis revealed NRBP1 protein expression in benign prostate hyperplasia in 6% as compared to 60% in both, high-grade intraepithelial neoplasia and prostate cancer samples. Strong NRBP1 protein expression was restricted to prostate cancer and correlated with higher expression of the proliferation marker Ki67 (P < 0.05). Further, patients with strong NRBP1 protein expression showed poor clinical outcomes (P < 0.05). Analysis of matched localized cancer tissues before and after castration revealed that post-therapy-related repression of NRBP1 expression was significantly associated with better overall survival.

CONCLUSIONS

We demonstrate that expression of NRBP1 is up-regulated during the progression of prostate cancer and that high NRBP1 expression is linked with poor prognosis and enhanced tumor cell growth.

Efficacy of cetuximab in metastatic castration-resistant prostate cancer might depend on EGFR and PTEN expression: results from a phase II trial (SAKK 08/07)

PURPOSE

The EGF receptor (EGFR) is overexpressed in the majority of metastatic castration-resistant prostate cancers (mCRPC) and might represent a valid therapeutic target. The combination of docetaxel and cetuximab, the monoclonal antibody against EGFR, has not been tested in patients with prostate cancer.

EXPERIMENTAL DESIGN

Patients with mCRPC progressing during or within 90 days after at least 12 weeks of docetaxel were included in this phase II trial. Treatment consisted of docetaxel (75 mg/m(2) every 3 weeks or 35 mg/m(2) on days 1, 8, 15 every 4 weeks) in combination with cetuximab (400 mg/m(2) on day 1 and then 250 mg/m(2) weekly). The primary endpoint was progression-free survival (PFS) at 12 weeks defined as the absence of prostate-specific antigen (PSA), radiographic, or clinical progression. Evaluation of known biomarkers of response and resistance to cetuximab (EGFR, PTEN, amphiregulin, epiregulin) was conducted.

RESULTS

Thirty-eight patients were enrolled at 15 Swiss centers. Median age was 68 years and median PSA was 212 ng/mL. PFS at 12 weeks was 34% [95% confidence interval (CI), 19%-52%], PFS at 24 weeks was 20%, and median overall survival (OS) was 13.3 months (95% CI, 7.3-15.4). Seven patients (20%) had a confirmed ≥ 50% and 11 patients (31%) a confirmed ≥ 30% PSA decline. About 47% of enrolled patients experienced grade 3 and 8% grade 4 toxicities. A significantly improved PFS was found in patients with overexpression of EGFR and persistent activity of PTEN.

CONCLUSIONS

EGFR inhibition with cetuximab might improve the outcome of patients with mCRPC. A potential correlation between EGFR overexpression, persistent expression of PTEN, and EGFR inhibition should be investigated further.

Proteomic differential display identifies upregulated vinculin as a possible biomarker of pancreatic cancer

Pancreatic cancer (PC) is characterized by rapid tumor spread, and very few patients with PC survive for more than 5 years. It is imperative to discover additional diagnostic biomarkers or specific therapeutic targets in order to improve the treatment of patients with PC. In search for useful biomarkers, we analyzed ten pairs of non-cancerous and cancer tissues from patients with PC by two-dimensional gel electrophoresis (2-DE). Nineteen protein spots showed differential expression on 2-DE gels between the cancer and non-cancerous tissues. Six upregulated protein spots were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) as calreticulin, glutathione synthetase, stathmin, vinculin, α-enolase and glyceraldehyde-3-phosphate dehydrogenase. Western blotting demonstrated that vinculin was predominantly expressed in the pancreatic cancer tissues compared with to non-cancerous tissues. Our findings indicate that vinculin may be a clinically useful biomarker of PC.

PAGE4 positivity is associated with attenuated AR signaling and predicts patient survival in hormone-naive prostate cancer

Aberrant activation of the androgen receptor (AR) plays a key role during prostate cancer (PCa) development and progression to castration-resistant prostate cancer (CR-PCa) after androgen deprivation therapy, the mainstay systemic treatment for PCa. New strategies to abrogate AR activity and biomarkers that predict aggressive tumor behavior are essential for improved therapeutic intervention. PCa tissue microarrays herein reveal that prostate-associated gene 4 (PAGE4), an X-linked cancer/testis antigen, is highly up-regulated in the epithelium of preneoplastic lesions compared with benign epithelium, but subsequently decreases with tumor progression. We show that AR signaling is attenuated in PAGE4-expressing cells both in vitro and in vivo, most likely via impaired androgen-induced AR nuclear translocation and subsequently reduced AR protein stabilization and phosphorylation at serines 81 and 213. Consistently, epithelial PAGE4 protein levels inversely correlated with AR activation status in hormone-naive and CR-PCa clinical specimens. Moreover, PAGE4 impaired the development of CR-PCa xenografts, and strong PAGE4 immunoreactivity independently predicted favorable patient survival in hormone-naive PCa. Collectively, these data suggest that dysregulation of epithelial PAGE4 modulates AR signaling, thereby promoting progression to advanced lethal PCa and highlight the potential value of PAGE4 as a prognostic and therapeutic target.

Proteomic analysis of microvesicles released by the human prostate cancer cell line PC-3

Cancer biomarkers are invaluable tools for cancer detection, prognosis, and treatment. Recently, microvesicles have appeared as a novel source for cancer biomarkers. We present here the results from a proteomic analysis of microvesicles released to the extracellular environment by the metastatic prostate cancer cell line PC-3. Using nanocapillary liquid chromatography-tandem mass spectrometry 266 proteins were identified with two or more peptide sequences. Further analysis showed that 16% of the proteins were classified as extracellular and that intracellular proteins were annotated in a variety of locations. Concerning biological processes, the proteins found in PC-3 cell-released microvesicles are mainly involved in transport, cell organization and biogenesis, metabolic process, response to stimulus, and regulation of biological processes. Several of the proteins identified (tetraspanins, annexins, Rab proteins, integrins, heat shock proteins, cytoskeletal proteins, 14-3-3 proteins) have previously been found in microvesicles isolated from other sources. However, some of the proteins seem to be more specific to the vesicular population released by the metastatic prostate cancer PC-3 cell line. Among these proteins are the tetraspanin protein CD151 and the glycoprotein CUB domain-containing protein 1. Interestingly, our results show these proteins are promising biomarkers for prostate cancer and therefore candidates for clinical validation studies in biological fluids.