Constraints to counting bioluminescence producing cells by a commonly used transgene promoter and its implications for experimental design.

It is routine to genetically modify cells to express fluorescent or bioluminescent reporter proteins to enable tracking or quantification of cells in vitro and in vivo. Herein, we characterized the stability of luciferase reporter systems in C4-2B prostate cancer cells in mono-culture and in co-culture with bone marrow-derived mesenchymal stem/stromal cells (BMSC). An assumption made when employing the luciferase reporter is that the luciferase expressing cell number and bioluminescence signal are linearly proportional. We observed instances where luciferase expression was significantly upregulated in C4-2B cell populations when co-cultured with BMSC, resulting in a significant disconnect between bioluminescence signal and cell number. We subsequently characterized luciferase reporter stability in a second C4-2B reporter cell line, and six other cancer cell lines. All but the single C4-2B reporter cell population had stable luciferase reporter expression in mono-culture and BMSC co-culture. Whole-genome sequencing revealed that relative number of luciferase gene insertions per genome in the unstable C4-2B reporter cell population was lesser than stable C4-2B, PC3 and MD-MBA-231 luciferase reporter cell lines. We reasoned that the low luciferase gene copy number and genome insertion locations likely contributed to the reporter gene expression being exquisitely sensitive BMSC paracrine signals. In this study, we show that it is possible to generate a range of stable and reliable luciferase reporter prostate- and breast- cancer cell populations but advise not to assume stability across different culture conditions. Reporter stability should be validated, on a case-by-case basis, for each cell line and culture condition.

The Microwell-mesh: A high-throughput 3D prostate cancer spheroid and drug-testing platform.

Treatment following early diagnosis of Prostate cancer (PCa) is increasingly successful, whilst the treatment of advanced and metastatic PCa remains challenging. A major limitation in the development of new therapies is the prediction of drug efficacy using in vitro models. Classic in vitro 2-dimensional (2D) cell monolayer cultures are hypersensitive to anti-cancer drugs. As a result, there has been a surge in the development of platforms that enable three dimensional (3D) cultures thought to better replicate natural physiology and better predict drug efficacy. A deficiency associated with most 3D culture systems is that their complexity reduces the number of replicates and combination therapies that can be feasibly evaluated. Herein, we describe the use of a microwell platform that utilises a nylon mesh to retain 3D micro-tumours in discrete microwells; termed the Microwell-mesh. The Microwell-mesh enables the manufacture of ~150 micro-tumours per well in a 48-well plate, and response to anti-tumour drugs can be readily quantified. Our results demonstrate that 3D micro-tumours, unlike 2D monolayers, are not hypersensitive to Docetaxel or Abiraterone Acetate, providing a superior platform for the evaluation of sequential drug treatment. In summary, the Microwell-mesh provides an efficient 3D micro-tumour platform for single and sequential drug screening.

A humanised tissue-engineered bone model allows species-specific breast cancer-related bone metastasis in vivo.

Bone metastases frequently occur in the advanced stages of breast cancer. At this stage, the disease is deemed incurable. To date, the mechanisms of breast cancer-related metastasis to bone are poorly understood. This may be attributed to the lack of appropriate animal models to investigate the complex cancer cell-bone interactions. In this study, two established tissue-engineered bone constructs (TEBCs) were applied to a breast cancer-related metastasis model. A cylindrical medical-grade polycaprolactone-tricalcium phosphate scaffold produced by fused deposition modelling (scaffold 1) was compared with a tubular calcium phosphate-coated polycaprolactone scaffold fabricated by solution electrospinning (scaffold 2) for their potential to generate ectopic humanised bone in NOD/SCID mice. While scaffold 1 was found not suitable to generate a sufficient amount of ectopic bone tissue due to poor ectopic integration, scaffold 2 showed excellent integration into the host tissue, leading to bone formation. To mimic breast cancer cell colonisation to the bone, MDA-MB-231, SUM1315, and MDA-MB-231BO breast cancer cells were cultured in polyethylene glycol-based hydrogels and implanted adjacent to the TEBCs. Histological analysis indicated that the breast cancer cells induced an osteoclastic reaction in the TEBCs, demonstrating analogies to breast cancer-related bone metastasis seen in patients.

Determining Protease Substrates Within a Complex Protein Background Using the PROtein TOpography and Migration Analysis Platform (PROTOMAP).

The PROtein TOpography and Migration Analysis Platform (PROTOMAP) approach is a degradomics technique used to determine protease substrates within complex protein backgrounds. The method involves protein separation according to protein relative mobility, using sodium dodecyl sulfate polyacrylamide gel electrophoresis. Gel lanes are then sliced into horizontal sections, and in-gel trypsin digestion performed for each gel slice. Extracted peptides and corresponding proteins are identified using liquid chromatography-tandem mass spectrometry and bioinformatics. Results are compiled in silico to generate a peptograph for every identified protein, being a pictorial representation of sodium dodecyl sulfate polyacrylamide gel electrophoresis. Proteins shown by their peptograph to have migrated further through the gel (i.e., to a lower gel slice) in the lane containing the active protease(s) of interest, as compared to the control, are deemed putative protease substrates. PROTOMAP has broad applicability to a range of experimental conditions and protein pools. Coupling this with its simple and robust methodology, the PROTOMAP approach has emerged as a valuable tool with which to determine protease substrates in complex systems.

The kallikrein-related peptidase family: Dysregulation and functions during cancer progression.

Cancer is the second leading cause of death with 14 million new cases and 8.2 million cancer-related deaths worldwide in 2012. Despite the progress made in cancer therapies, neoplastic diseases are still a major therapeutic challenge notably because of intra- and inter-malignant tumour heterogeneity and adaptation/escape of malignant cells to/from treatment. New targeted therapies need to be developed to improve our medical arsenal and counter-act cancer progression. Human kallikrein-related peptidases (KLKs) are secreted serine peptidases which are aberrantly expressed in many cancers and have great potential in developing targeted therapies. The potential of KLKs as cancer biomarkers is well established since the demonstration of the association between KLK3/PSA (prostate specific antigen) levels and prostate cancer progression. In addition, a constantly increasing number of in vitro and in vivo studies demonstrate the functional involvement of KLKs in cancer-related processes. These peptidases are now considered key players in the regulation of cancer cell growth, migration, invasion, chemo-resistance, and importantly, in mediating interactions between cancer cells and other cell populations found in the tumour microenvironment to facilitate cancer progression. These functional roles of KLKs in a cancer context further highlight their potential in designing new anti-cancer approaches. In this review, we comprehensively review the biochemical features of KLKs, their functional roles in carcinogenesis, followed by the latest developments and the successful utility of KLK-based therapeutics in counteracting cancer progression.

Murine, but not human, ephrin-B2 can be efficiently cleaved by the serine protease kallikrein-4: implications for xenograft models of human prostate cancer.

BACKGROUND: Ephrin-B2 is the sole physiologically-relevant ligand of the receptor tyrosine kinase EphB4, which is over-expressed in many epithelial cancers, including 66% of prostate cancers, and contributes to cancer cell survival, invasion and migration. Crucially, however, the cancer-promoting EphB4 signalling pathways are independent of interaction with its ligand ephrin-B2, as activation of ligand-dependent signalling causes tumour suppression. Ephrin-B2, however, is often found on the surface of endothelial cells of the tumour vasculature, where it can regulate angiogenesis to support tumour growth. Proteolytic cleavage of endothelial cell ephrin-B2 has previously been suggested as one mechanism whereby the interaction between tumour cell-expressed EphB4 and endothelial cell ephrin-B2 is regulated to support both cancer promotion and angiogenesis. METHODS: An in silico approach was used to search accessible surfaces of 3D protein models for cleavage sites for the key prostate cancer serine protease, KLK4, and this identified murine ephrin-B2 as a potential KLK4 substrate. Mouse ephrin-B2 was then confirmed as a KLK4 substrate by in vitro incubation of recombinant mouse ephrin-B2 with active recombinant human KLK4. Cleavage products were visualised by SDS-PAGE, silver staining and Western blot and confirmed by N-terminal sequencing. RESULTS: At low molar ratios, KLK4 cleaved murine ephrin-B2 but other prostate-specific KLK family members (KLK2 and KLK3/PSA) were less efficient, suggesting cleavage was KLK4-selective. The primary KLK4 cleavage site in murine ephrin-B2 was verified and shown to correspond to one of the in silico predicted sites between extracellular domain residues arginine 178 and asparagine 179. Surprisingly, the highly homologous human ephrin-B2 was poorly cleaved by KLK4 at these low molar ratios, likely due to the 3 amino acid differences at this primary cleavage site. CONCLUSION: These data suggest that in in vivo mouse xenograft models, endogenous mouse ephrin-B2, but not human tumour ephrin-B2, may be a downstream target of cancer cell secreted human KLK4. This is a critical consideration when interpreting data from murine explants of human EphB4+/KLK4+ cancer cells, such as prostate cancer cells, where differential effects may be seen in mouse models as opposed to human clinical situations.

PITX2 and non-canonical Wnt pathway interaction in metastatic prostate cancer.

The non-canonical Wnt pathway, a regulator of cellular motility and morphology, is increasingly implicated in cancer metastasis. In a quantitative PCR array analysis of 84 Wnt pathway associated genes, both non-canonical and canonical pathways were activated in primary and metastatic tumors relative to normal prostate. Expression of the Wnt target gene PITX2 in a prostate cancer (PCa) bone metastasis was strikingly elevated over normal prostate (over 2,000-fold) and primary prostate cancer (over 200-fold). The elevation of PITX2 protein was also evident on tissue microarrays, with strong PITX2 immunostaining in PCa skeletal and, to a lesser degree, soft tissue metastases. PITX2 is associated with cell migration during normal tissue morphogenesis. In our studies, overexpression of individual PITX2A/B/C isoforms stimulated PC-3 PCa cell motility, with the PITX2A isoform imparting a specific motility advantage in the presence of non-canonical Wnt5a stimulation. Furthermore, PITX2 specific shRNA inhibited PC-3 cell migration toward bone cell derived chemoattractant. These experimental results support a pivotal role of PITX2A and non-canonical Wnt signaling in enhancement of PCa cell motility, suggest PITX2 involvement in homing of PCa to the skeleton, and are consistent with a role for PITX2 in PCa metastasis to soft and bone tissues. Our findings, which significantly expand previous evidence that PITX2 is associated with risk of PCa biochemical recurrence, indicate that variation in PITX2 expression accompanies and may promote prostate tumor progression and metastasis.

Growth of confined cancer spheroids: a combined experimental and mathematical modelling approach.

A critical step in the dissemination of ovarian cancer is the formation of multicellular spheroids from cells shed from the primary tumour. The objectives of this study were to apply bioengineered three-dimensional (3D) microenvironments for culturing ovarian cancer spheroids in vitro and simultaneously to build on a mathematical model describing the growth of multicellular spheroids in these biomimetic matrices. Cancer cells derived from human epithelial ovarian carcinoma were embedded within biomimetic hydrogels of varying stiffness and grown for up to 4 weeks. Immunohistochemistry, imaging and growth analyses were used to quantify the dependence of cell proliferation and apoptosis on matrix stiffness, long-term culture and treatment with the anti-cancer drug paclitaxel. The mathematical model was formulated as a free boundary problem in which each spheroid was treated as an incompressible porous medium. The functional forms used to describe the rates of cell proliferation and apoptosis were motivated by the experimental work and predictions of the mathematical model compared with the experimental output. This work aimed to establish whether it is possible to simulate solid tumour growth on the basis of data on spheroid size, cell proliferation and cell death within these spheroids. The mathematical model predictions were in agreement with the experimental data set and simulated how the growth of cancer spheroids was influenced by mechanical and biochemical stimuli including matrix stiffness, culture duration and administration of a chemotherapeutic drug. Our computational model provides new perspectives on experimental results and has informed the design of new 3D studies of chemoresistance of multicellular cancer spheroids.

Identification of a novel prostate cancer susceptibility variant in the KLK3 gene transcript.

Genome-wide association studies (GWAS) have identified more than 30 prostate cancer (PrCa) susceptibility loci. One of these (rs2735839) is located close to a plausible candidate susceptibility gene, KLK3, which encodes prostate-specific antigen (PSA). PSA is widely used as a biomarker for PrCa detection and disease monitoring. To refine the association between PrCa and variants in this region, we used genotyping data from a two-stage GWAS using samples from the UK and Australia, and the Cancer Genetic Markers of Susceptibility (CGEMS) study. Genotypes were imputed for 197 and 312 single nucleotide polymorphisms (SNPs) from HapMap2 and the 1000 Genome Project, respectively. The most significant association with PrCa was with a previously unidentified SNP, rs17632542 (combined P = 3.9 × 10(-22)). This association was confirmed by direct genotyping in three stages of the UK/Australian GWAS, involving 10,405 cases and 10,681 controls (combined P = 1.9 × 10(-34)). rs17632542 is also shown to be associated with PSA levels and it is a non-synonymous coding SNP (Ile179Thr) in KLK3. Using molecular dynamic simulation, we showed evidence that this variant has the potential to introduce alterations in the protein or affect RNA splicing. We propose that rs17632542 may directly influence PrCa risk.

Compartmentalized expression of kallikrein 4 (KLK4/hK4) isoforms in prostate cancer: nuclear, cytoplasmic and secreted forms.

The prostate-specific antigen-related serine protease gene, kallikrein 4 (KLK4), is expressed in the prostate and, more importantly, overexpressed in prostate cancer. Several KLK4 mRNA splice variants have been reported, but it is still not clear which of these is most relevant to prostate cancer. Here we report that, in addition to the full-length KLK4 (KLK4-254) transcript, the exon 1 deleted KLK4 transcripts, in particular, the 5'-truncated KLK4-205 transcript, is expressed in prostate cancer. Using V5/His6 and green fluorescent protein (GFP) carboxy terminal tagged expression constructs and immunocytochemical approaches, we found that hK4-254 is cytoplasmically localized, while the N-terminal truncated hK4-205 is in the nucleus of transfected PC-3 prostate cancer cells. At the protein level, using anti-hK4 peptide antibodies specific to different regions of hK4-254 (N-terminal and C-terminal), we also demonstrated that endogenous hK4-254 (detected with the N-terminal antibody) is more intensely stained in malignant cells than in benign prostate cells, and is secreted into seminal fluid. In contrast, for the endogenous nuclear-localized N-terminal truncated hK4-205 form, there was less difference in staining intensity between benign and cancer glands. Thus, KLK4-254/hK4-254 may have utility as an immunohistochemical marker for prostate cancer. Our studies also indicate that the expression levels of the truncated KLK4 transcripts, but not KLK4-254, are regulated by androgens in LNCaP cells. Thus, these data demonstrate that there are two major isoforms of hK4 (KLK4-254/hK4-254 and KLK4-205/hK4-205) expressed in prostate cancer with different regulatory and expression profiles that imply both secreted and novel nuclear roles.

Kallikrein 4 (hK4) and prostate-specific antigen (PSA) are associated with the loss of E-cadherin and an epithelial-mesenchymal transition (EMT)-like effect in prostate cancer cells.

Prostate-specific antigen (PSA) and the related kallikrein family of serine proteases are current or emerging biomarkers for prostate cancer detection and progression. Kallikrein 4 (KLK4/hK4) is of particular interest, as KLK4 mRNA has been shown to be elevated in prostate cancer. In this study, we now show that the comparative expression of hK4 protein in prostate cancer tissues, compared with benign glands, is greater than that of PSA and kallikrein 2 (KLK2/hK2), suggesting that hK4 may play an important functional role in prostate cancer progression in addition to its biomarker potential. To examine the roles that hK4, as well as PSA and hK2, play in processes associated with progression, these kallikreins were separately transfected into the PC-3 prostate cancer cell line, and the consequence of their stable transfection was investigated. PC-3 cells expressing hK4 had a decreased growth rate, but no changes in cell proliferation were observed in the cells expressing PSA or hK2. hK4 and PSA, but not hK2, induced a 2.4-fold and 1.7-fold respective increase, in cellular migration, but not invasion, through Matrigel, a synthetic extracellular matrix. We hypothesised that this increase in motility displayed by the hK4 and PSA-expressing PC-3 cells may be related to the observed change in structure in these cells from a typical rounded epithelial-like cell to a spindle-shaped, more mesenchymal-like cell, with compromised adhesion to the culture surface. Thus, the expression of E-cadherin and vimentin, both associated with an epithelial-mesenchymal transition (EMT), was investigated. E-cadherin protein was lost and mRNA levels were significantly decreased in PC-3 cells expressing hK4 and PSA (10-fold and 7-fold respectively), suggesting transcriptional repression of E-cadherin, while the expression of vimentin was increased in these cells. The loss of E-cadherin and associated increase in vimentin are indicative of EMT and provides compelling evidence that hK4, in particular, and PSA have a functional role in the progression of prostate cancer through their promotion of tumour cell migration.

Hypermethylation of the 5' CpG island of the gene encoding the serine protease Testisin promotes its loss in testicular tumorigenesis.

The Testisin gene (PRSS21) encodes a glycosylphosphatidylinositol (GPI)-linked serine protease that exhibits testis tissue-specific expression. Loss of Testisin has been implicated in testicular tumorigenesis, but its role in testis biology and tumorigenesis is not known. Here we have investigated the role of CpG methylation in Testisin gene inactivation and tested the hypothesis that Testisin may act as a tumour suppressor for testicular tumorigenesis. Using sequence analysis of bisulphite-treated genomic DNA, we find a strong relationship between hypermethylation of a 385 bp 5' CpG rich island of the Testisin gene, and silencing of the Testisin gene in a range of human tumour cell lines and in 100% (eight/eight) of testicular germ cell tumours. We show that treatment of Testisin-negative cell lines with demethylating agents and/or a histone deacetylase inhibitor results in reactivation of Testisin gene expression, implicating hypermethylation in Testisin gene silencing. Stable expression of Testisin in the Testisin-negative Tera-2 testicular cancer line suppressed tumorigenicity as revealed by inhibition of both anchorage-dependent cell growth and tumour formation in an SCID mouse model of testicular tumorigenesis. Together, these data show that loss of Testisin is caused, at least in part, by DNA hypermethylation and histone deacetylation, and suggest a tumour suppressor role for Testisin in testicular tumorigenesis.

Polyethylene glycol/surfactant mixtures improve lung function after HCl and endotoxin lung injuries.

Addition of nonionic polymers such as polyethylene glycol (PEG) and dextran ameliorates inactivation of Survanta by a variety of substances in vitro. Addition of polymers to Survanta also improves pulmonary function when used to treat rats with lung injury caused by instillation of human meconium. To find whether this approach is effective in lung injuries that more closely resemble adult respiratory distress syndrome (ARDS), we have compared the use of Survanta with Survanta + PEG in two additional models of lung injury caused by either lipopolysaccharide (LPS) or HCl in adult rats. Significant improvement of serial measures for arterial oxygenation and of postmortem pressure-volume measurements were found after treatment with Survanta + PEG compared with Survanta alone. PEG added to Survanta increased resistance to inactivation caused by tracheal fluid taken from animals injured with HCl. Other work suggests that PEG promotes surfactant aggregation, separates surfactant from surfactant inhibitors, and enhances access of surfactant to the gas-liquid interface. The addition of polymers to surfactants may also be useful in the treatment of lung injury where inactivation of surfactant has already occurred.

TTYH2, a human homologue of the Drosophila melanogaster gene tweety, is located on 17q24 and upregulated in renal cell carcinoma.

Using differential display PCR, we identified a novel gene upregulated in renal cell carcinoma. Characterization of the full-length cDNA and gene revealed that the encoded protein is a human homologue of the Drosophila melanogaster Tweety protein, and so we have termed the novel protein TTYH2. The orthologous mouse cDNA was also identified and the predicted mouse protein is 81% identical to the human protein. The encoded human TTYH2 protein is 534 amino acids and, like the other members of the tweety-related protein family, is a putative cell surface protein with five transmembrane regions. TTYH2 is located at 17q24; it is expressed most highly in brain and testis and at lower levels in heart, ovary, spleen, and peripheral blood leukocytes. Expression of this gene is upregulated in 13 of 16 (81%) renal cell carcinoma samples examined. In addition to a putative role in brain and testis, the over-expression of TTYH2 in renal cell carcinoma suggests that it may have an important role in kidney tumorigenesis.

NO2 interfacial transfer is reduced by phospholipid monolayers.

Nitrogen dioxide (NO2) is a ubiquitous, pollutant gas that produces a broad range of pathological and physiological effects on the lung. Absorption of inhaled NO2 is coupled to near-interfacial reactions between the solute gas and constituents of the airway and alveolar epithelial lining fluid. Although alveolar surfactant imparts limited resistance to respiratory gas exchange compared with that contributed by either the pulmonary membrane or uptake in red blood cells, resistance to NO2 flux could have a significant effect on NO2 absorption kinetics. To investigate the effect of interfacial surfactant on NO2 absorption, we designed an apparatus permitting exposure of variably compressed monolayers. Our results suggest that compressed monolayers enriched in 1,2-dipalmitoyl-sn-3-glycero-phosphocholine present significant resistance to NO2 absorption even at surface tensions greater than those achieved in vivo. However, monolayers composed of pure unsaturated phospholipids failed to alter NO2 absorption significantly when compressed, in spite of similar reductions in surface tension. The results demonstrate that phospholipid monolayers appreciably limit NO2 absorption and further that monolayer-induced resistance to NO2 flux is related to physicochemical properties of the film itself rather than alterations within the aqueous and gas phases. On the basis of these findings, we propose that pulmonary surfactant may influence the intrapulmonary gas phase distribution of inhaled NO2.

Characterization of a novel gene, STAG1/PMEPA1, upregulated in renal cell carcinoma and other solid tumors.

Using differential display-polymerase chain reaction, we identified a novel gene sequence, designated solid tumor-associated gene 1 (STAG1), that is upregulated in renal cell carcinoma (RCC). The full-length cDNA (4839 bp) encompassed the recently reported androgen-regulated prostatic cDNA PMEPA1, and so we refer to this gene as STAG1/PMEPA1. Two STAG1/PMEPA1 mRNA transcripts of approximately 2.7 and 5 kb, with identical coding regions but variant 3' untranslated regions, were predominantly expressed in normal prostate tissue and at lower levels in the ovary. The expression of this gene was upregulated in 87% of RCC samples and also was upregulated in stomach and rectal adenocarcinomas. In contrast, STAG1/PMEPA1 expression was barely detectable in leukemia and lymphoma samples. Analysis of expressed sequence tag databases showed that STAG1/PMEPA1 also was expressed in pancreatic, endometrial, and prostatic adenocarcinomas. The STAG1/PMEPA1 cDNA encodes a 287-amino-acid protein containing a putative transmembrane domain and motifs that suggest that it may bind src homology 3- and tryptophan tryptophan domain-containing proteins. This protein shows 67% identity to the protein encoded by the chromosome 18 open reading frame 1 gene. Translation of STAG1/PMEPA1 mRNA in vitro showed two products of 36 and 39 kDa, respectively, suggesting that translation may initiate at more than one site. Comparison to genomic clones showed that STAG1/PMEPA1 was located on chromosome 20q13 between microsatellite markers D20S183 and D20S173 and spanned four exons and three introns. The upregulation of this gene in several solid tumors indicated that it may play an important role in tumorigenesis.

Human kallikrein 4 (KLK4) is highly expressed in serous ovarian carcinomas.

Previous studies indicated that a new member of the human kallikrein (KLK) gene family, KLK4, was expressed in prostate, breast, and endometrial carcinoma cell lines and may have potential as a tumor marker. The aim of this study was to examine the expression of KLK4 in the normal ovary and ovarian tumors of different histology, stage, and differentiation and to determine its association with ovarian tumor progression. Using reverse transcription-PCR, Southern blot, and densitometry analyses, we found the level of KLK4 expression was higher in late stage serous (SER) epithelial-derived ovarian carcinomas than in normal ovaries, mucinous epithelial tumors, and granulosa cell tumors. KLK4 was highly expressed in all of the SER ovarian carcinoma cell lines (eight of eight), SER epithelial carcinomas (11 of 11), and two adenomas, whereas it was expressed at a lower level (or not at all) in normal ovaries (four of six), mucinous epithelial tumors (three of four), endometrioid carcinomas (four of five), clear cell carcinomas (two of three), or granulosa cell tumors (three of six). Of particular interest, KLK4 mRNA variants were detected in SER ovarian carcinoma cell lines and primary cultured ovarian tumor cells, but they were not present in normal ovaries. In situ hybridization analysis showed that KLK4 mRNA transcripts are localized to adenocarcinoma cells of ovarian tumor tissues. Similarly, immunohistochemical staining of ovarian carcinoma sections showed immunoreactivity to KLK4 protein product (hK4) antipeptide antibodies. In addition, intracellular hK4 levels, as detected on Western blot analysis, were induced by 100 nM estrogen treatment of the estrogen receptor positive ovarian carcinoma cell line OVCAR-3, >8-24 h. Our results show that the level of KLK4 expression and expression of KLK4 mRNA variants are associated with progression of ovarian cancer, particularly late stage SER adenocarcinomas. Moreover, hK4 may be a candidate marker for the diagnosis and/or monitoring of ovarian epithelial carcinomas.

Kallikrein gene expression in the gonadotrophin-stimulated rat ovary.

The kallikreins (KLKs) are a highly conserved multi-gene family of serine proteases that are expressed in a wide variety of tissues and act on a diverse range of substrates. KLK-like enzyme activity has variously been reported to increase or decrease during the period leading up to ovulation in the equine chorionic gonadotrophin (eCG)primed, human chorionic gonadotrophin (hCG)-stimulated immature rat ovary. These earlier studies, which used biochemical assays to detect enzyme activity, lacked the specificity and sensitivity necessary to characterise conclusively the activity of the individual KLK gene family members. In this study, we have used a gene-specific RT-PCR/Southern hybridisation strategy to delineate the expression patterns of six of the individual KLK genes expressed in the rat ovary (rKLK1-3 and rKLK7-9). We have identified three broad patterns of expression in the eCG/hCG-stimulated ovary in which there is either a post-eCG increase/pre-ovulatory decrease in rKLK expression (rKLK1, rKLK3), a peri-ovulatory decrease in expression (rKLK2, rKLK8) or a relatively unchanged pattern of expression (rKLK7, rKLK9). In addition to clarifying the earlier biochemical studies, these findings support a differential role for the individual KLKs in the ovulatory process.

Identification and characterization of KLK14, a novel kallikrein serine protease gene located on human chromosome 19q13.4 and expressed in prostate and skeletal muscle.

The kallikreins are a subfamily of serine proteases encoded in human, mouse, and rat by highly conserved tightly clustered multigene families. Here we report the identification and characterization of KLK14, a novel kallikrein gene located within the human kallikrein locus at 19q13.4. KLK14 is approximately 5.4 kb in length spanning seven exons and, by Northern blot analysis, transcribes two alternative transcripts present only in prostate (1.5 kb) and skeletal muscle (1.9 kb). The protein product, K14, predicted to be a 251-amino-acid secreted serine protease with trypsin-like substrate specificity, is translated in vitro with a molecular mass of approximately 31 kDa. In situ hybridization revealed that, in prostate, KLK14 is expressed by both benign and malignant glandular epithelial cells, thus exhibiting an expression pattern similar to that of two other prostatic kallikreins, KLK2 and KLK3, which encode K2 and prostate-specific antigen, respectively.