Protein expression of matriptase and its cognate inhibitor HAI-1 in human prostate cancer: a tissue microarray and automated quantitative analysis

Predicting chemosensitivity using drug perturbed gene dynamics

Background

One of the current directions of precision medicine is the use of computational methods to aid in the diagnosis, prognosis, and treatment of disease based on data driven approaches. For instance, in oncology, there has been a particular focus on development of algorithms and biomarkers that can be used for pre-clinical and clinical applications. In particular large-scale omics-based models to predict drug sensitivity in in vitro cancer cell line panels have been used to explore the utility and aid in the development of these models as clinical tools. Additionally, a number of web-based interfaces have been constructed for researchers to explore the potential of drug perturbed gene expression as biomarkers including the NCI Transcriptional Pharmacodynamic Workbench. In this paper we explore the influence of drug perturbed gene dynamics of the NCI Transcriptional Pharmacodynamics Workbench in computational models to predict in vitro drug sensitivity for 15 drugs on the NCI60 cell line panel.

Results

This work presents three main findings. First, our models show that gene expression profiles that capture changes in gene expression after 24 h of exposure to a high concentration of drug generates the most accurate predictive models compared to the expression profiles under different dosing conditions. Second, signatures of 100 genes are developed for different gene expression profiles; furthermore, when the gene signatures are applied across gene expression profiles model performance is substantially decreased when gene signatures developed using changes in gene expression are applied to non-drugged gene expression. Lastly, we show that the gene interaction networks developed on these signatures show different network topologies and can be used to inform selection of cancer relevant genes.

Conclusion

Our models suggest that perturbed gene signatures are predictive of drug response, but cannot be applied to predict drug response using unperturbed gene expression. Furthermore, additional drug perturbed gene expression measurements in in vitro cell lines could generate more predictive models; but, more importantly be used in conjunction with computational methods to discover important drug disease relationships.

Dysregulation of Type II Transmembrane Serine Proteases and Ligand-Dependent Activation of MET in Urological Cancers

Unlike in normal epithelium, dysregulated overactivation of various proteases have been reported in cancers. Degradation of pericancerous extracellular matrix leading to cancer cell invasion by matrix metalloproteases is well known evidence. On the other hand, several cell-surface proteases, including type II transmembrane serine proteases (TTSPs), also induce progression through activation of growth factors, protease activating receptors and other proteases. Hepatocyte growth factor (HGF) known as a multifunctional growth factor that upregulates cancer cell motility, invasiveness, proliferative, and anti-apoptotic activities through phosphorylation of MET (a specific receptor of HGF). HGF secreted as inactive zymogen (pro-HGF) from cancer associated stromal fibroblasts, and the proteolytic activation by several TTSPs including matriptase and hepsin is required. The activation is strictly regulated by HGF activator inhibitors (HAIs) in physiological condition. However, downregulation is frequently observed in cancers. Indeed, overactivation of MET by upregulation of matriptase and hepsin accompanied by the downregulation of HAIs in urological cancers (prostate cancer, renal cell carcinoma, and bladder cancer) are also reported, a phenomenon observed in cancer cells with malignant phenotype, and correlated with poor prognosis. In this review, we summarized current reports focusing on TTSPs, HAIs, and MET signaling axis in urological cancers.

Cell surface-anchored serine proteases in cancer progression and metastasis

Over the last two decades, a novel subgroup of serine proteases, the cell surface-anchored serine proteases, has emerged as an important component of the human degradome, and several members have garnered significant attention for their roles in cancer progression and metastasis. A large body of literature describes that cell surface-anchored serine proteases are deregulated in cancer and that they contribute to both tumor formation and metastasis through diverse molecular mechanisms. The loss of precise regulation of cell surface-anchored serine protease expression and/or catalytic activity may be contributing to the etiology of several cancer types. There is therefore a strong impetus to understand the events that lead to deregulation at the gene and protein levels, how these precipitate in various stages of tumorigenesis, and whether targeting of selected proteases can lead to novel cancer intervention strategies. This review summarizes current knowledge about cell surface-anchored serine proteases and their role in cancer based on biochemical characterization, cell culture-based studies, expression studies, and in vivo experiments. Efforts to develop inhibitors to target cell surface-anchored serine proteases in cancer therapy will also be summarized.

Semen AMACR protein as a novel method for detecting prostate cancer

BACKGROUND

Alpha methylacyl A coenzyme racemase (AMACR) has shown to be an excellent immunohistological biomarker for prostate cancer (CaP). Given the connection between prostate and urethra, we hypothesized that semen ejaculate would be an ideal specimen for detection of CaP specific biomarkers, such as AMACR. This study explores the detection of semen AMACR protein in men with and without CaP.

METHODS

Semen ejaculates from 28 biopsy proven CaP patients prior to radical prostatectomy and 15 age-comparable controls were analyzed. An indirect sandwich ELISA chemiluminescence assay was used to detect semen AMACR, PSA, and Matriptase proteins. Tissue AMACR protein was quantified in 12 corresponding prostatectomy specimens using automated quantitative analysis (AQUA).

RESULTS

Semen AMACR protein was detected in 23 of 28 (82%) CaP patients and 23 of 24 (96%) CaP patients with significant tumor volume (>0.5 cc or 0.3 g). Among the 5 cancer patients with undetectable semen AMACR, 4 patients had small tumor volumes (<1% or 0.3 g). Semen AMACR protein was also detected in 7 of 15 (47%) control noncancer patients. Using 76 ng/ml as a cutoff value, 20 of 28 (71%) patients and 20 of 24 (83%) patients with significant tumor volume were positive for semen AMACR protein, whereas only 5 of 15 (33%) age-comparable controls were positive. AMACR levels degrade with time.

CONCLUSIONS

This is the first study to demonstrate that AMACR protein is detectable in semen ejaculate. The higher AMACR levels detected in cancer patients suggests that semen AMACR protein may be useful as a noninvasive test for prostate cancer. Further validation is warranted.

Delineating the HMGB1 and HMGB2 interactome in prostate and ovary epithelial cells and its relationship with cancer

High Mobility Group B (HMGB) proteins are involved in cancer progression and in cellular responses to platinum compounds used in the chemotherapy of prostate and ovary cancer. Here we use affinity purification coupled to mass spectrometry (MS) and yeast two-hybrid (Y2H) screening to carry out an exhaustive study of HMGB1 and HMGB2 protein interactions in the context of prostate and ovary epithelia. We present a proteomic study of HMGB1 partners based on immunoprecipitation of HMGB1 from a non-cancerous prostate epithelial cell line. In addition, HMGB1 and HMGB2 were used as baits in yeast two-hybrid screening of libraries from prostate and ovary epithelial cell lines as well as from healthy ovary tissue. HMGB1 interacts with many nuclear proteins that control gene expression, but also with proteins that form part of the cytoskeleton, cell-adhesion structures and others involved in intracellular protein translocation, cellular migration, secretion, apoptosis and cell survival. HMGB2 interacts with proteins involved in apoptosis, cell motility and cellular proliferation. High confidence interactors, based on repeated identification in different cell types or in both MS and Y2H approaches, are discussed in relation to cancer. This study represents a useful resource for detailed investigation of the role of HMGB1 in cancer of epithelial origins, as well as potential alternative avenues of therapeutic intervention.

Phase Ib placebo-controlled, tissue biomarker trial of diindolylmethane (BR-DIMNG) in patients with prostate cancer who are undergoing prostatectomy

Epidemiologic, preclinical, and early phase I studies of the cruciferous vegetable bioactive metabolite, 3,3'-diindolylmethane (DIM), support its potential prostate cancer chemopreventive ability. We performed a multicenter, double-blind, placebo-controlled trial of DIM in patients diagnosed with prostate cancer and scheduled for radical prostatectomy. A total of 45 patients with organ-confined prostate cancer were randomized to 21-28 days of an absorption-enhanced formulation of DIM (BR-DIM) at doses of 100 or 200 mg per os twice daily or to placebo twice daily. Prostate tissue levels of DIM were the primary endpoint, with selected secondary biomarker endpoints including blood levels of DIM, total prostate-specific antigen, testosterone, and the insulin-like growth factor-1: insulin-like growth factor binding protein-3 ratio and the urinary 2-hydroxyestrone/16-hydroxyestrone ratio, obtained at baseline, at day 15, and before surgery, as well as tissue expression of androgen receptor, prostate-specific antigen, Ki67, caspase 3 with cytochrome p450 mRNA expression and genotyping (polymorphisms). DIM was well tolerated with excellent study compliance and relatively rapid accrual of all 45 patients within 1 year. DIM levels were detected in only seven of 28 prostate tissue specimens. There was a statistically significant difference in the change in the urinary 2-hydroxyestrone/16-hydroxyestrone ratio from baseline until before surgery between the placebo and 400 mg DIM groups, with otherwise statistically nonsignificant changes in plasma biomarker expression. The administration of BR-DIM to prostate cancer patients before prostatectomy yields detectable plasma levels but without consistent or significant tissue accumulation or biomarker modulation. This study demonstrates the feasibility of biologic evaluation of relatively nontoxic preventive agents in the preprostatectomy setting with the potential for rapid accrual.

KLK14 interactions with HAI-1 and HAI-2 serine protease inhibitors: A molecular dynamics and relative free-energy calculations study

Kallikrein 14 (KLK14) is a serine protease linked to several pathologies including prostate cancer and positively correlates with Gleason score. Though KLK14 functioning in cancer is poorly understood, it has been implicated in HGF/Met signaling, given that KLK14 proteolytically inhibits HGF activator-inhibitor 1 (HAI-1), which strongly inhibits pro-HGF activators, thereby contributing to tumor progression. In this work, KLK14 binding to either hepatocyte growth factor activator inhibitor type-1 (HAI-1) or type-2 (HAI-2) was essayed using homology modeling, molecular dynamic simulations and free-energy calculations through MM/PBSA and MM/GBSA. KLK14 was successfully modeled. Calculated free energies suggested higher binding affinity for the KLK14/HAI-1 interaction than for KLK14/HAI-2. This difference in binding affinity is largely explained by the higher stability of the hydrogen-bond networks in KLK14/HAI-1 along the simulation trajectory. A key arginine residue in both HAI-1 and HAI-2 is responsible for their interaction with the S1 pocket in KLK14. Additionally, MM/GBSA free-energy decomposition postulates that KLK14 Asp174 and Trp196 are hotspots for binding HAI-1 and HAI-2.

Persistence of senescent prostate cancer cells following prolonged neoadjuvant androgen deprivation therapy

Purpose

Androgen deprivation therapy (ADT) commonly leads to incomplete cell death and the fate of persistent cells involves, in part, a senescent phenotype. Senescence is terminal growth arrest in response to cell stress that is characterized by increased lysosomal-β-galactosidase (GLB1) the origin of senescence associated-β-gal activity (SA-β-gal). In the current study senescence is examined in vivo after ADT use in a neoadjuvant trial.

Methods and materials

Tissue microarrays were generated from prostate cancer specimens (n = 126) from a multicenter neoadjuvant ADT trial. Arrays were subjected to multiplexed immunofluorescent staining for GLB1, Ki67, cleaved caspase 3 (CC3) and E-cadherin. Automated quantitative imaging was performed using Vectra™ and expression correlated with clinicopathologic features.

Results

Tissue was analyzed from 59 patients treated with neoadjuvant ADT and 67 receiving no therapy preoperatively. Median follow-up was 85.3 mo and median ADT treatment was 5 mo. In PC treated with neoadjuvant ADT, GLB1 expression increased in intermediate Gleason score (GS 6–7; p = 0.001), but not high grade (GS 8–10) cancer. Significantly higher levels of GLB1 were seen in tissues undergoing neoadjuvant ADT longer than 5 months compared to untreated tissues (p = 0.002). In contrast, apoptosis significantly increased earlier (1–4 mo) after ADT treatment (p<0.5).

Conclusions

Increased GLB1 after neoadjuvant ADT occurs primarily among more clinically favorable intermediate grade cancers and enrichment of the phenotype occurs in a temporally prolonged fashion. Senescence may explain the persistence of PCa cells after ADT. Given concerns for the detrimental longer term presence of senescent cells, targeting these cells for removal may improve outcomes.

In vitro evidence that KLK14 regulates the components of the HGF/Met axis, pro-HGF and HGF-activator inhibitor 1A and 1B

Kallikrein-related peptidase (KLK) 14 is a serine protease linked to several pathologies including prostate cancer. We show that KLK14 has biphasic effects in vitro on activating and inhibiting components of the prostate cancer associated hepatocyte growth factor (HGF)/Met system. At 5–10 nm, KLK14 converts pro-HGF to the two-chain heterodimer required for Met activation, while higher concentrations degrade the HGF α-chain. HGF activator-inhibitor (HAI)-1A and HAI-1B, which inhibit pro-HGF activators, are degraded by KLK14 when protease:inhibitor stoichiometry is 1:1 or the protease is in excess. When inhibitors are in excess, KLK14 generates HAI-1A and HAI-1B fragments known to inhibit pro-HGF activating serine proteases. These in vitro data suggest that increased KLK14 activity could contribute at multiple levels to HGF/Met-mediated processes in prostate and other cancers.

Expression of spermidine/spermine N(1) -acetyl transferase (SSAT) in human prostate tissues is related to prostate cancer progression and metastasis

INTRODUCTION

Prostate cancer (PCa) in many patients remains indolent for the rest of their lives, but in some patients, it progresses to lethal metastatic disease. Gleason score is the current clinical method for PCa prognosis. It cannot reliably identify aggressive PCa, when GS is ≤ 7. It is shown that oxidative stress plays a key role in PCa progression. We have shown that in cultured human PCa cells, an activation of spermidine/spermine N(1) -acetyl transferase (SSAT; EC 2.3.1.57) enzyme initiates a polyamine oxidation pathway and generates copious amounts of reactive oxygen species in polyamine-rich PCa cells.

METHOD

We used RNA in situ hybridization and immunohistochemistry methods to detect SSAT mRNA and protein expression in two tissue microarrays (TMA) created from patient's prostate tissues. We analyzed 423 patient's prostate tissues in the two TMAs.

RESULTS

Our data show that there is a significant increase in both SSAT mRNA and the enzyme protein in the PCa cells as compared to their benign counterpart. This increase is even more pronounced in metastatic PCa tissues as compared to the PCa localized in the prostate. In the prostatectomy tissues from early-stage patients, the SSAT protein level is also high in the tissues obtained from the patients who ultimately progress to advanced metastatic disease.

DISCUSSION

Based on these results combined with published data from our and other laboratories, we propose an activation of an autocrine feed-forward loop of PCa cell proliferation in the absence of androgen as a possible mechanism of castrate-resistant prostate cancer growth.

Overexpression of the novel senescence marker β-galactosidase (GLB1) in prostate cancer predicts reduced PSA recurrence

Purpose

Senescence is a terminal growth arrest that functions as a tumor suppressor in aging and precancerous cells and is a response to selected anticancer compounds. Lysosomal-β-galactosidase (GLB1) hydrolyzes β-galactose from glycoconjugates and is the origin of senescence-associated β-gal activity (SA-β-gal). Using a new GLB1 antibody, senescence biology was investigated in prostate cancer (PCa) tissues.

Experimental Design

In vitro characterization of GLB1 was determined in primary prostate epithelial cell cultures passaged to replicative senescence and in therapy-induced senescence in PCa lines using chemotherapeutic agents. FFPE tissue microarrays were subjected to immunofluorescent staining for GLB1, Ki67 and HP1γ and automated quantitative imaging initially using AQUA in exploratory samples and Vectra in a validation series.

Results

GLB1 expression accumulates in replicative and induced senescence and correlates with senescent morphology and P16 (CDKN2) expression. In tissue arrays, quantitative imaging detects increased GLB1 expression in high-grade prostatic intraepithelial neoplasia (HGPIN), known to contain senescent cells, and cancer compared to benign prostate tissues (p<0.01) and senescent cells contain low Ki67 and elevated HP1γ. Within primary tumors, elevated GLB1 associates with lower T stage (p=0.01), localized versus metastatic disease (p=0.0003) and improved PSA-free survival (p=0.03). Increased GLB1 stratifies better PSA-free survival in intermediate grade PCa (0.01). Tissues that elaborate higher GLB1 display increased uniformity of expression.

Conclusion

Increased GLB1 is a valuable marker in formalin-fixed paraffin-embedded (FFPE) tissues for the senescence-like phenotype and associates with improved cancer outcomes. This protein addresses a lack of senescence markers and should be applicable to study the biologic role of senescence in other cancers.

Hepatocyte growth factor activator inhibitor type‑1 in cancer: advances and perspectives (Review)

Cancer is one of the most common diseases, with high morbidity and mortality rates. Large‑scale efforts have been made to understand the pathogenesis of the disease, particularly in the advanced stages, in order to develop effective therapeutic approaches. Hepatocyte growth factor activator inhibitor type-1 (HAI-1), also known as serine protease inhibitor Kunitz type 1, inhibits the activity of several trypsin-like serine proteases. In particular, HAI-1 suppresses hepatocyte growth factor (HGF) activator and matriptase, resulting in subsequent inhibition of HGF/scatter factor and macrophage‑stimulating protein (MSP). HGF and MSP are involved in cancer development and progression, via the receptors Met receptor tyrosine kinase (RTK) and Ron RTK, respectively. Therefore, HAI-1-mediated downregulation of HGF and MSP signaling may suppress tumorigenesis and progression in certain types of cancers. Abnormal HAI-1 expression levels have been observed in various types of human cancer. The exact function of HAI-1 in cancer pathogenesis, however, has not been fully elucidated. In this review, the focus is on the potential impact of aberrant HAI-1 expression levels on tumorigenesis and progression, the underlying mechanisms, and areas that require further investigation to clarify the precise role of HAI-1 in cancer.

Down-regulation of HAI-1 is associated with poor-differentiation status of colorectal cancer

Hepatocyte growth factor activator inhibitor type 1 (HAI-1) is a Kunitz-type serine protease inhibitor which is widely expressed in epithelial cells. The purpose of this study is to investigate the relationship between HAI-1 expression and differentiation status of colorectal epithelia. The expression of HAI-1 in clinical samples of both cancerous and normal colorectal tissues was evaluated by immunohistochemical staining. An in vitro epithelial differentiation model of Caco-2 cell was established, and the characteristics of differentiation of Caco-2 cells were observed by transmission electron microscopy. The expression of HAI-1 in Caco-2 cells at different differentiation stages was examined by western blot. Immunohistochemical staining of 52 human colorectal cancer tissues showed a definite correlation between HAI-1 expression and differentiation status: IHC score (mean ± SE) of HAI-1 was higher for well- or moderately-differentiated colorectal cancer tissues than for poorly-differentiated colorectal cancer tissues, with significant differences in HAI-1 positive rate (P < 0.01 and P < 0.05 for well-differentiated vs. poorly-differentiated and moderately-differentiated vs. poorly-differentiated, respectively). Immunohistochemical staining of normal colorectal tissues showed positive HAI-1 expression in well-differentiated epithelial cells whereas the under-differentiated crypt cells showed very weak HAI-1 staining signals. The result of western blot also showed the gradual increasing of HAI-1 expression during the process of Caco-2 differentiation in vitro. HAI-1 expression correlates with the differentiation status of colorectal epithelia and could serve as a differentiation marker.

Sex steroid receptor expression and localization in benign prostatic hyperplasia varies with tissue compartment

Androgens and estrogens, acting via their respective receptors, are important in benign prostatic hyperplasia (BPH). The goals of this study were to quantitatively characterize the tissue distribution and staining intensity of androgen receptor (AR) and estrogen receptor-alpha (ERα), and assess cells expressing both AR and ERα, in human BPH compared to normal prostate. A tissue microarray composed of normal prostate and BPH tissue was used and multiplexed immunohistochemistry was performed to detect AR and ERα. We used a multispectral imaging platform for automated scanning, tissue and cell segmentation and marker quantification. BPH specimens had an increased number of epithelial and stromal cells and increased percentage of epithelium. In both stroma and epithelium, the mean nuclear area was decreased in BPH relative to normal prostate. AR expression and staining intensity in epithelial and stromal cells was significantly increased in BPH compared to normal prostate. ERα expression was increased in BPH epithelium. However, stromal ERα expression and staining intensity was decreased in BPH compared to normal prostate. Double positive (AR and ERα) epithelial cells were more prevalent in BPH, and fewer double negative (AR and ERα) stromal and epithelial negative cells were observed in BPH. These data underscore the importance of tissue layer localization and expression of steroid hormone receptors in the prostate. Understanding the tissue-specific hormone action of androgens and estrogens will lead to a better understanding of mechanisms of pathogenesis in the prostate and may lead to better treatment for BPH.

Identification of estrogen receptor dimer selective ligands reveals growth-inhibitory effects on cells that co-express ERα and ERβ

Estrogens play essential roles in the progression of mammary and prostatic diseases. The transcriptional effects of estrogens are transduced by two estrogen receptors, ERα and ERβ, which elicit opposing roles in regulating proliferation: ERα is proliferative while ERβ is anti-proliferative. Exogenous expression of ERβ in ERα-positive cancer cell lines inhibits cell proliferation in response to estrogen and reduces xenografted tumor growth in vivo, suggesting that ERβ might oppose ERα's proliferative effects via formation of ERα/β heterodimers. Despite biochemical and cellular evidence of ERα/β heterodimer formation in cells co-expressing both receptors, the biological roles of the ERα/β heterodimer remain to be elucidated. Here we report the identification of two phytoestrogens that selectively activate ERα/β heterodimers at specific concentrations using a cell-based, two-step high throughput small molecule screen for ER transcriptional activity and ER dimer selectivity. Using ERα/β heterodimer-selective ligands at defined concentrations, we demonstrate that ERα/β heterodimers are growth inhibitory in breast and prostate cells which co-express the two ER isoforms. Furthermore, using Automated Quantitative Analysis (AQUA) to examine nuclear expression of ERα and ERβ in human breast tissue microarrays, we demonstrate that ERα and ERβ are co-expressed in the same cells in breast tumors. The co-expression of ERα and ERβ in the same cells supports the possibility of ERα/β heterodimer formation at physio- and pathological conditions, further suggesting that targeting ERα/β heterodimers might be a novel therapeutic approach to the treatment of cancers which co-express ERα and ERβ.

Mechanisms for the control of matriptase activity in the absence of sufficient HAI-1

Matriptase proteolytic activity must be tightly controlled for normal placental development, epidermal function, and epithelial integrity. Although hepatocyte growth factor activator inhibitor-1 (HAI-1) represents the predominant endogenous inhibitor for matriptase and the protein molar ratio of HAI-1 to matriptase is determined to be >10 in epithelial cells and the majority of carcinoma cells, an inverse HAI-1-to-matriptase ratio is seen in some ovarian and hematopoietic cancer cells. In the current study, cells with insufficient HAI-1 are investigated for the mechanisms through which the activity of matriptase is regulated. When matriptase activation is robustly induced in these cells, activated matriptase rapidly forms two complexes of 100- and 140-kDa in addition to the canonical 120-kDa matriptase-HAI-1 complex already described. Both 100- and 140-kDa complexes contain two-chain, cleaved matriptase but are devoid of gelatinolytic activity. Further biochemical characterization shows that the 140-kDa complex is a matriptase homodimer and that the 100-kDa complexes appear to contain reversible, tight binding serine protease inhibitor(s). The formation of the 140-kDa matriptase dimer is strongly associated with matriptase activation, and its levels are inversely correlated with the ratio of HAI-1 to matriptase. Given these observations and the likelihood that autoactivation requires the interaction of two matriptase molecules, it seems plausible that this activated matriptase homodimer may represent a matriptase autoactivation intermediate and that its accumulation may serve as a mechanism to control matriptase activity when protease inhibitor levels are limiting. These data suggest that matriptase activity can be rapidly inhibited by HAI-1 and other HAI-1-like protease inhibitors and "locked" in an inactive autoactivation intermediate, all of which places matriptase under very tight control.

Matriptase is inhibited by extravascular antithrombin in epithelial cells but not in most carcinoma cells

Antithrombin, a major anticoagulant, is robustly transported into extravascular compartments where its target proteases are largely unknown. This serpin was previously detected in human milk as complexes with matriptase, a membrane-bound serine protease broadly expressed in epithelial and carcinoma cells, and under tight regulation by hepatocyte growth factor activator inhibitor (HAI)-1, a transmembrane Kunitz-type serine protease inhibitor that forms heat-sensitive complexes with active matriptase. In the current study, we detect, in addition to matriptase-HAI-1 complexes, heat-resistant matriptase complexes generated by nontransformed mammary, prostate, and epidermal epithelial cells that we show to be matriptase-antithrombin complexes. These findings suggest that in addition to HAI-1, interstitial antithrombin participates in the regulation of matriptase activity in epithelial cells. This physiological mechanism appears, however, to largely be lost in cancer cells since matriptase-antithrombin complexes were not detected in all but two of a panel of seven breast, prostate, and ovarian cancer cell lines. Using purified active matriptase, we further characterize the formation of matriptase-antithrombin complex and show that heparin can significantly potentiate the inhibitory potency of antithrombin against matriptase. Second-order rate constants for the inhibition were determined to be 3.9 × 10(3) M(-1)s(-1) in the absence of heparin and 1.2 × 10(5) M(-1)s(-1) in the presence of heparin, a 30-fold increase, consistent with the established role of heparin in activating antithrombin function. Taken together these data suggest that normal epithelial cells employ a dual mechanism involving HAI-1 and antithrombin to control matriptase and that the antithrombin-based mechanism appears lost in the majority of carcinoma cells.

Eastern Cooperative Oncology Group Phase II Trial of lapatinib in men with biochemically relapsed, androgen dependent prostate cancer

PURPOSE

Activation of the epidermal growth factor pathway is important in prostate cancer development and the transcription of androgen receptor regulated genes. This study evaluated the potential activity of lapatinib in men with biochemically-relapsed androgen-dependent (stage D0) prostate cancer.

PATIENTS AND METHODS

Patients with a rising PSA after primary therapy for prostate cancer were enrolled. A PSA doubling time (PSADT) <12 months was required. Lapatinib was administered at 1,500 mg orally daily. Outcome measures were changes in PSA kinetics. Primary tumor blocks were obtained and assessed for EGFR expression, EGFR Q787Q polymorphism, and Kras 38 mutational status.

RESULTS

Forty-nine patients were enrolled (14 ineligible), resulting in 35 patients for analysis. No PSA response was observed; best response was stable disease (n = 28, 80.0%). Pretreatment average slope was 0.19 log (PSA)/month (PSADT = 3.70 months), in contrast to on-treatment average slope of 0.13 log (PSA)/month (PSADT = 5.44 months) using linear mixed effects models (P = 0.006). Median progression-free survival (PFS) was 17.4 months for the high EGFR group and 6.0 months for the low EGFR group (P = 0.50). Patients with Kras 38 mutation had shorter PFS than those without Kras 38 mutation (P = 0.09).

CONCLUSION

Although no PSA responses (primary endpoint) was observed, lapatinib may have biologic activity in men with stage D0 prostate cancer as evidenced by a decrease in PSA slope in this non-randomized study. Additional trials assessing the role of EGFR overexpression and Kras wild type status in prostate cancer should be investigated.

Laminin-332 cleavage by matriptase alters motility parameters of prostate cancer cells

BACKGROUND

Matriptase, a type II transmembrane serine protease, has been linked to initiation and promotion of epidermal carcinogenesis in a murine model, suggesting that deregulation of its role in epithelia contributes to transformation. In human prostate cancer, matriptase expression correlates with progression. It is therefore of interest to determine how matriptase may contribute to epithelial neoplastic progression. One approach for studying this is to identify potential matriptase substrates involved in epithelial integrity and/or transformation like the extracellular matrix macromolecule, laminin-332 (Ln-332), which is found in the basement membrane of many epithelia, including prostate. Proteolytic processing of Ln-332 regulates cell motility of both normal and transformed cells, which has implications in cancer progression.

METHODS

In vitro cleavage experiments were performed with purified Ln-332 protein and matriptase. Western blotting, enzyme inhibition assays, and mass spectrometry were used to confirm cleavage events. Matriptase overexpressing LNCaP prostate cancer cells were generated and included in Transwell migration assays and single cell motility assays, along with other prostate cells.

RESULTS

We report that matriptase proteolytically cleaves Ln-332 in the β3 chain. Substrate specificity was confirmed by blocking cleavage with the matriptase inhibitor, Kunitz domain-1. Transwell migration assays showed that DU145 cell motility was significantly enhanced when plated on matriptase-cleaved Ln-332. Similarly, Transwell migration of matriptase-overexpressing LNCaP cells was significantly increased on Ln-332 and, as determined by live single-cell microscopy, two motility parameters of this cell line, speed and directional persistence, were also higher.

CONCLUSIONS

Proteolytic processing of Ln-332 by matriptase enhances speed and directional persistence of prostate cancer cells.

Use of tissue microarray and automated quantitative analysis for screening and validation of potential biomarkers in mantle cell lymphoma

BACKGROUND

Cancer biomarker studies using the combination of tissue microarray and automated quantitative assessment of immunofluorescence (TMA-AQUA) have been successfully performed for various types of human carcinoma, but its performance characteristics have yet to be evaluated in human lymphoma.

METHODS

A pilot TMA was constructed containing duplicate 1.5 mm cores from 15 cases of mantle cell lymphoma (MCL), 3 cases of low-grade B-cell lymphoma, and 3 cases of benign lymphoid tissue. Protein expression of c-Myc, Cdc2, Cyclin D1, Ki-67, Mcm2, and p27 by immunofluorescence and chromagenic staining were evaluated by AQUA and visual scoring, respectively. Gene expression of cMYC, CDC2, and CCND1 was determined by quantitative nuclease protection assay.

RESULTS

Protein expression between duplicate cores determined by AQUA showed excellent correlation for all markers [correlation coefficient (R)=0.79 to 0.94] and Cyclin D1 expression was significantly higher in MCL cases compared with non-MCL cases (P=0.00019). Overall correlation of AQUA with scoring of chromagenic staining by 2 pathologists was good for all markers (R=0.56 to 0.90), except Cdc2 (R=0.25). Localization of expression to cytoplasmic and/or nuclear compartments was comparable with chromagenic staining patterns for all markers except Ki-67 and Mcm2, where a significant difference between nuclear and cytoplasmic expression could not be appreciated by AQUA, despite clear nuclear localization by chromagenic staining. Correlation of gene expression with protein expression was variable for CDC2, cMYC, and CCND1 (R=0.32, 0.35, and 0.69).

CONCLUSIONS

TMA-AQUA has the potential to be successfully used as a high-throughput protein biomarker screening platform for MCL; however, appropriate target protein selection and antibody performance validation are factors that need to be considered.

Loss of the matriptase inhibitor HAI-2 during prostate cancer progression

BACKGROUND

Prostate cancer progression is accompanied by increased levels of extracellular proteases that are capable of remodeling the extracellular matrix as well as cleaving and activating growth factors and their receptors that are critically involved in pro-cancerous signaling pathways. The membrane anchored serine protease matriptase (also known as MT-SP1, epithin, and TADG15) has been implicated in prostate cancer. Several studies have demonstrated that the expression of this protease, both on the RNA and protein level is significantly increased during prostate cancer progression. Hepatocyte activator growth factor inhibitor-2 (HAI-2) has recently been identified as a physiological inhibitor of matriptase. It has been proposed that the increase of matriptase with a concomitant loss of its inhibitors may play a critical role in cancer progression.

METHODS

In this study, we used immunohistochemistry to determine the expression of HAI-2 protein in 136 prostate cancer samples, 20 prostate benign prostatic hyperplasia (BPH) samples, and 31 normal or tumor-adjacent prostate samples. Specificity of detection was ensured by using two unrelated HAI-2 antibodies and corresponding non-immune IgG antibodies.

RESULTS

We demonstrate that HAI-2 protein is significantly decreased in malignant lesions as compared to normal and BPH lesions, and that the most poorly differentiated tumors (Gleason score 8-10) have the lowest level of HAI-2 expression.

CONCLUSION

These data suggest that the loss of HAI-2 may be actively involved in prostate cancer progression by causing a reduced inhibitory capacity of proteolysis possibly of the physiological target for HAI-2 matriptase.

Melatonin resynchronizes dysregulated circadian rhythm circuitry in human prostate cancer cells

Prostate cancer (PCa) is a major age-related malignancy as increasing age correlates with increased risk for developing this neoplasm. Similarly, alterations in circadian rhythms have also been associated with the aging population and cancer risk. The pineal hormone melatonin is known to regulate circadian rhythms, which is under the control of a core set of genes: Period 1, 2, 3 (Per 1-3); Cryptochrome 1, 2 (Cry 1, 2); Clock, and Bmal 1, 2. Melatonin levels have been shown to decrease in patients with cancer and exogenous melatonin exhibits antiproliferative effects against certain cancers. In this study, we challenged the hypothesis that melatonin imparts antiproliferative effects in prostate cancer via resynchronization of deregulated core clock circuitry. We found that Clock and Per2 protein levels were downregulated whereas Bmal1 protein levels were upregulated in PCa cells, compared to normal prostate cells. Additionally, employing automated quantitative analysis of a microarray containing human tissues, we found that compared to benign tissues, Clock and Per2 levels were downregulated, whereas Bmal1 levels were upregulated in PCa and other proliferative prostatic conditions. Overexpression of Per2 was found to result in a significant loss of PCa cell growth and viability. Interestingly, melatonin treatment resulted in an increase in Per2 and Clock and a reduction in Bmal1 in PCa cells. Further, melatonin treatment resulted in a resynchronization of oscillatory circadian rhythm genes (Dbp and Per2). Our data support our hypothesis and suggest that melatonin should be thoroughly investigated as an agent for the management of PCa and other age-related malignancies.

Induction of autophagy and inhibition of melanoma growth in vitro and in vivo by hyperactivation of oncogenic BRAF

Activating mutations in NRAS and BRAF are found frequently in cutaneous melanomas. Because concurrent mutations of both BRAF and RAS are extremely rare, it is thought that transformation by RAS and BRAF occurs through a common mechanism. Also, there is evidence for a relationship of synthetic lethality between NRAS and BRAF oncogenes that leads to selection against cells with a hyperactive mitogen-activated protein kinase (MAPK) pathway. However, it is not known whether the hyperactivation of the MAPK pathway by overexpression of either oncogene alone could also inhibit melanoma tumorigenesis. Here, we show that in melanoma cells with oncogenic BRAF (mBRAF), high levels of mBRAF induce hyperactivation of ERK and senescence-like phenotype and trigger autophagy by inhibiting the mammalian target of rapamycin complex signaling. Growth inhibition and cell death caused by high mBRAF levels are partially rescued by downregulation of BRAF protein or inhibition of autophagy, but not by inhibition of the MAPK or apoptotic pathways. In nude mice, growth of mBRAF-overexpressing tumors is inhibited. Quantitative immunohistochemical analysis of human melanomas and cell lines showed a significant positive correlation between the levels of BRAF protein and autophagy marker light chain 3. Our data suggest that high oncogenic BRAF levels trigger autophagy, which may have a role in melanoma tumor progression.

TMPRSS2, a serine protease expressed in the prostate on the apical surface of luminal epithelial cells and released into semen in prostasomes, is misregulated in prostate cancer cells

TMPRSS2, a type II transmembrane serine protease, is highly expressed by the epithelium of the human prostate gland. To explore the regulation and function of TMPRSS2 in the prostate, a panel of monoclonal antibodies with high sensitivity and specificity were generated. Immunodetection showed TMPRSS2 on the apical plasma membrane of the prostate luminal cells and demonstrated its release into semen as a component of prostasomes, organelle-like vesicles that may facilitate sperm function and enhance male reproduction. In prostate cancer cells, TMPRSS2 expression was increased and the protein mislocalized over the entire tumor cell membrane. In both LNCaP prostate cancer cells and human semen, TMPRSS2 protein was detected predominantly as inactive zymogen forms as part of an array of multiple noncovalent and disulfide-linked complexes, suggesting that TMPRSS2 activity may be regulated by unconventional mechanisms. Our data suggested that TMPRSS2, an apical surface serine protease, may have a normal role in male reproduction as a component of prostasomes. The aberrant cellular localization, and increased expression of the protease seen in cancer, may contribute to prostate tumorigenesis by providing access of the enzyme to nonphysiological substrates and binding-proteins.

Evaluation of mRNA by Q-RTPCR and protein expression by AQUA of the M2 subunit of ribonucleotide reductase (RRM2) in human tumors

PURPOSE

The purpose of this study was to evaluate baseline RRM2 protein and gene expression in tumors of patients receiving 3-AP.

METHODS

Tumor blocks from patients enrolled in phase I and II clinical studies using 3-AP, were evaluated for RRM2 gene and protein expression by quantitative real time polymerase chain reaction (Q-RTPCR) and automated quantitative analysis (AQUA).

RESULTS

Esophageal and gastric cancers overexpressed RRM2 protein when compared to prostate cancer (Z-score, 0.68 +/- 0.94 SD, vs 0.41 +/- 0.84 SD, respectively; p = 0.04). Esophageal and gastric cancers also overexpressed RRM2 mRNA when compared to prostate cancer (relative gene expression 2.56 +/- 1.49 SD, vs 0.29 +/- 0.20 SD, respectively; p = 0.02). Protein and gene expression were moderately associated (Spearman's rank correlation = 0.30; p = 0.12).

CONCLUSION

RRM2 gene and protein expression varies by tumor type.

Identification of PDE4D as a proliferation promoting factor in prostate cancer using a Sleeping Beauty transposon-based somatic mutagenesis screen

Retroviral and transposon-based mutagenesis screens in mice have been useful for identifying candidate cancer genes for some tumor types. However, many of the organs that exhibit the highest cancer rates in humans, including the prostate, have not previously been amenable to these approaches. This study shows for the first time that the Sleeping Beauty transposon system can be used to identify candidate prostate cancer genes in mice. Somatic mobilization of a mutagenic transposon resulted in focal epithelial proliferation and hyperplasia in the prostate. Efficient methods were established to identify transposon insertion sites in these lesions, and analysis of transposon insertions identified candidate prostate cancer genes at common insertion sites, including Pde4d. PDE4D was also overexpressed in human prostate cancer patient samples and cell lines, and changes in PDE4D mRNA isoform expression were observed in human prostate cancers. Furthermore, knockdown of PDE4D reduced the growth and migration of prostate cancer cells in vitro, and knockdown of PDE4D reduced the growth and proliferation rate of prostate cancer xenografts in vivo. These data indicate that PDE4D functions as a proliferation promoting factor in prostate cancer, and the Sleeping Beauty transposon system is a useful tool for identifying candidate prostate cancer genes.

Matriptase: a culprit in cancer?

Pericellular proteases can degrade extracellular matrix proteins and reshape their microenvironment, as well as cleave and activate signaling molecules such as growth factors and their receptors. In this capacity, pericellular proteolysis is essential for multiple biological processes, including development, tissue homeostasis and tissue repair. On the flip side, dysregulated pericellular proteolysis is a hallmark in many pathological conditions including cancer, and is believed to be critically involved in tumor growth, invasion and dissemination of cancer cells to other organs. Matriptase is a member of the family of Type II transmembrane serine proteases, and has been implicated in a variety of epithelial cancers. This review summarizes current knowledge about matriptase and its role in cancer based on expression studies, biochemical characterization, cell-culture based studies and in vivo experiments.