Association of KLK5 overexpression with invasiveness of urinary bladder carcinoma cells

KLK6 Functions as an Oncogene and Unfavorable Prognostic Factor in Bladder Urothelial Carcinoma

Background

Kallikrein-related peptidase 6 (KLK6) has been substantiated as a diagnostic, prognostic, and therapeutic molecular in several cancer types. In our study, we attempt to explore the biological functions of KLK6 in bladder urothelial carcinoma (BLCA).

Methods

KLK6 gene expression prognostic, gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), gene set enrichment analysis (GSEA), and immune infiltration were analyzed using The Cancer Genome Atlas (TCGA) database. In vitro and in vivo experimental measurements, including CCK8, transwell migration, TUNEL, and nude mouse transplanted tumor model, were used to evaluate the antineoplastic activities of KLK6 loss-of-function.

Results

The combination of bioinformatics analyses and experimental measurements demonstrate that KLK6 expression is aberrantly upregulated in human specimens and cell lines of BLCA. GO and GSEA enrichment analyses exhibited that KLK6 is implicated in the inflammatory response and immune infiltration, suggesting that upregulation of KLK6 may be associated with the progression of BLCA. Knockdown of KLK6 is able to inhibit the growth and migration and trigger apoptosis of RT4 and T24 cells. Moreover, the TCGA database indicates that KLK6 high expression in BLCA patients showed a poorer prognosis than those patients with KLK6 low expression. Univariate and multivariate regression analyses suggest KLK6 as an independent prognostic factor to predict unfavorable OS in patients with BLCA.

Conclusion

KLK6 is an independent prognostic factor and an antitumor target of BLCA. KLK6 expression positively correlates with several immune cells infiltration, indicating that inhibition of KLK6 may contribute to immunotherapy of BLCA.

Clinical significance of kallikrein 5 as a novel prognostic biomarker in gastric adenocarcinoma

Backgrounds

Gastric cancer is one of the most common cancers with unsatisfied prognosis. It is challenging to predict gastric cancer prognosis due to its highly heterogeneous nature. Kallikrein 5 (KLK5) belongs to the family of kallikreins, which plays a crucial role in serine proteolysis and exerts diverse physiological functions. The role of KLK5 in human gastric adenocarcinoma (GAC) has not been elucidated. In the present study, we aimed to examine the expression level of KLK5 and dissect whether the KLK5 expression was associated with GAC prognosis.

Patients and methods

Clinicopathological analyses were performed in a retrospective GAC patient cohort (n = 138). The expression of KLK5 was tested by quantitative RT‐PCR and immunohistochemistry staining. The prognostic role of KLK5 in GAC was assessed by univariate and multivariate analyses. The effects of KLK5 on cell proliferation, migration, and invasion were examined through cellular experiments.

Results

The data showed that KLK5 expression was elevated in GAC tissues compared with normal stomach tissues. Protein expression of KLK5 was positively correlated with tumor invasion depth and lymph node metastasis. Patients with higher KLK5 expression had poorer overall survival. KLK5 was identified to be an independent risk factor according to multivariate analysis. Using human GAC cell lines, we found that KLK5 can promote tumor cell migration and invasion.

Conclusions

Our study demonstrated that higher expression of KLK5 was significantly correlated with a poorer prognosis of GAC patients, implying the potential of KLK5 as a novel prognostic biomarker in GAC.

Quantitative assessment and clinical relevance of kallikrein-related peptidase 5 mRNA expression in advanced high-grade serous ovarian cancer

Background

In ovarian cancer, dysregulation of mRNA expression of several components of the family of the kallikrein-related peptidases (KLKs) is observed. In this study, we have analyzed the KLK5 mRNA expression pattern in tumor tissue of patients suffering from high-grade serous ovarian cancer stage FIGO III/IV. Moreover, we have correlated the KLK5 mRNA levels with clinical outcome.

Methods

We assessed the mRNA expression levels of KLK5 in tumor tissue of 138 patients using quantitative PCR (qPCR). The mRNA levels were correlated with KLK5 antigen tumor tissue levels measured by ELISA (available for 41 of the 138 patients), established clinical features as well as patients’ outcome, using Chi-square-tests, Mann-Whitney U-tests and Spearman rank calculations as well as Cox regression models, Kaplan-Meier survival analysis and the log-rank test.

Results

A highly significant correlation between the mRNA expression levels and protein levels of KLK5 in tumor tissues was observed (r_s = 0.683, p < 0.001). In univariate Cox regression analysis, elevated KLK5 mRNA expression was remarkably associated with reduced progression-free survival (PFS; p = 0.047), but not with overall survival (OS). Association of KLK5 mRNA expression with PFS was validated in silico using The Cancer Genome Atlas. For this, Affymetrix-based mRNA data (n = 377) were analyzed applying the Kaplan-Meier Plotter tool (p = 0.027). In multivariable Cox analysis, KLK5 mRNA values revealed a trend towards statistical significance for PFS (p = 0.095), whereas residual tumor mass (0 mm vs. > 0 mm), but not ascites fluid volume (≤500 ml vs. > 500 ml), remained an independent indicator for both OS and PFS (p < 0.001, p = 0.005, respectively).

Conclusions

These results obtained with a homogenous patient group with all patients suffering from advanced high-grade serous ovarian cancer support previous results suggesting elevated KLK5 mRNA levels as an unfavorable marker in ovarian cancer.

Effect of Productive Human Papillomavirus 16 Infection on Global Gene Expression in Cervical Epithelium

Human papillomavirus (HPV) infection is the world's most common sexually transmitted infection and is responsible for most cases of cervical cancer. Previous studies of global gene expression changes induced by HPV infection have focused on the cancerous stages of infection, and therefore, not much is known about global gene expression changes at early preneoplastic stages of infection. We show for the first time the global gene expression changes during early-stage HPV16 infection in cervical tissue using 3-dimensional organotypic raft cultures, which produce high levels of progeny virions. cDNA microarray analysis showed that a total of 594 genes were upregulated and 651 genes were downregulated at least 1.5-fold with HPV16 infection. Gene ontology analysis showed that biological processes including cell cycle progression and DNA metabolism were upregulated, while skin development, immune response, and cell death were downregulated with HPV16 infection in cervical keratinocytes. Individual genes were selected for validation at the transcriptional and translational levels, including UBC, which was central to the protein association network of immune response genes, and top downregulated genes RPTN, SERPINB4, KRT23, and KLK8 In particular, KLK8 and SERPINB4 were shown to be upregulated in cancer, which contrasts with the gene regulation during the productive replication stage. Organotypic raft cultures, which allow full progression of the HPV life cycle, allowed us to identify novel gene modulations and potential therapeutic targets of early-stage HPV infection in cervical tissue. Additionally, our results suggest that early-stage productive infection and cancerous stages of infection are distinct disease states expressing different host transcriptomes.IMPORTANCE Persistent HPV infection is responsible for most cases of cervical cancer. The transition from precancerous to cancerous stages of HPV infection is marked by a significant reduction in virus production. Most global gene expression studies of HPV infection have focused on the cancerous stages. Therefore, little is known about global gene expression changes at precancerous stages. For the first time, we measured global gene expression changes at the precancerous stages of HPV16 infection in human cervical tissue producing high levels of virus. We identified a group of genes that are typically overexpressed in cancerous stages to be significantly downregulated at the precancerous stage. Moreover, we identified significantly modulated genes that have not yet been studied in the context of HPV infection. Studying the role of these genes in HPV infection will help us understand what drives the transition from precancerous to cancerous stages and may lead to the development of new therapeutic targets.

Clinical utility of kallikrein-related peptidases (KLK) in urogenital malignancies

Kallikrein-related peptidases (KLK), which represent a major tissue-associated proteolytic system, stand for a rich source of biomarkers that may allow molecular classification, early diagnosis and prognosis of human malignancies as well as prediction of response or failure to cancer-directed drugs. International research points to an important role of certain KLKs in female and male urogenital tract malignancies, in addition to cancers of the lung, brain, skin, head and neck, and the gastrointestinal tract. Regarding the female/male urogenital tract, remarkably, all of the KLKs are expressed in the normal prostate, testis, and kidney whereas the uterus, the ovary, and the urinary bladder are expressing a limited number of KLKs only. Most of the information regarding KLK expression in tumour-affected organs is available for ovarian cancer; all of the 12 KLKs tested so far were found to be elevated in the malignant state, depicting them as valuable biomarkers to distinguish between the normal and the cancerous phenotype. In contrast, for kidney cancer, a series of KLKs was found to be downregulated, while other KLKs were not expressed. Evidently, depending on the type of cancer or cancer stage, individual KLKs may show characteristics of a Janus-faced behaviour, by either expanding or inhibiting cancer progression and metastasis.

Kallikrein-related peptidase expression in odontogenic cysts and tumors: An immunohistochemical comparative study

AIM

The aim of the present study was to profile the expression of human kallikrein (KLK)-related peptidases (KLK) in odontogenic lesions.

METHODS

Paraffin-embedded, formalin-fixed, non-odontogenic (control) and odontogenic lesions were stained for KLK using a standard immunohistochemical technique. The intensity and proportion of epithelial cells stained was scored. Reverse transcription-polymerase chain reaction was utilized to evaluate KLK 1-15 mRNA expression in ameloblastomas.

RESULTS

KLK 3, 4, 9, 11, and 14 were present in all lesions. KLK 3 staining was increased in ameloblastomas and keratocystic odontogenic tumors. KLK 5 was present only in Keratocystic odontogenic tumor. KLK 6 was significantly higher in ameloblastomas than in other lesions. For KLK 7, keratocystic odontogenic tumors and nasopalatine duct cysts were significantly different. KLK 6, 8, 10, 11, and 13 were significantly higher in ameloblastomas than in other lesions. KLK 9 was increased in keratocystic odontogenic tumors and dentigerous cysts. The expression of KLK 1, 4, 7, 8, 10, and 12 mRNA was found in ameloblastomas.

CONCLUSION

The results suggested that KLK 6, 8, 10, and 13 could be involved in the progression of ameloblastomas. KLK 10 could have a greater role in odontogenic lesions, rather than non-odontogenic lesions. Future studies aim to define the specific roles of KLK cascades in odontogenic lesions.

Downregulated KLK13 expression in bladder cancer highlights tumor aggressiveness and unfavorable patients' prognosis

PURPOSE

Despite recent research advantages on the molecular and subcellular background, bladder cancer (BlCa) remains a clinically neglected malignancy. This is strongly reflected by the generic approach of disease diagnosis and management. Additionally, patients' prognosis became a rather demanding task due to the great disease heterogeneity. Here, we aimed to evaluate, for the first time, the clinical value of KLK13 in BlCa.

METHODS

A total of 279 bladder specimens (137 tumors, 107 adjacent normal tissues and 35 healthy samples) were included. Total RNA was extracted, reverse transcribed, and KLK13 expression was assessed by quantitative real-time PCR.

RESULTS

KLK13 expression is significantly increased in bladder tumors compared to normal adjacent epithelium. However, reduced KLK13 expression is correlated with disease aggressiveness, including higher tumor stage and grade, and high-risk TaT1 tumors according to the EORTC stratification. Moreover, Kaplan-Meier and Cox regression analysis highlighted the prognostic value of the reduced KLK13 expression for the prediction of TaT1 patients' recurrence and shorter disease-free survival following TURBT. Finally, the combination of KLK13 expression with EORTC-risk stratification results to an improved prediction of TaT1 patients' outcome.

CONCLUSION

This first clinical study of KLK13 in BlCa reveals its deregulated expression in bladder tumors and highlights KLK13 as a promising marker for improving TaT1 patients' prognosis following treatment.

Growth and survival of lung cancer cells: regulation by kallikrein-related peptidase 6 via activation of proteinase-activated receptor 2 and the epidermal growth factor receptor

The dysregulated expression of kallikrein-related peptidase 6 (KLK6) is involved in non-small cancer (NSCLC) cell growth. However, the mechanism that sustains KLK6 signaling remains unknown. We used an isogenic non-small cell lung cancer (NSCLC) cell model system to demonstrate that KLK6 promotes the proliferation of lung tumoral cells and restrains their apoptosis in vitro via ligand-dependent EGFR transactivation. KLK6 activated the ERK and Akt pathways and triggered the nuclear translocation of β-catenin. The stimulating effects of KLK6 required its proteolytic activity and were dependent on the protease-activated receptor 2 (PAR2). These observations support the concept of a role for KLK6 in the oncogenesis of NSCLC.

Development of monoclonal antibodies to human kallikrein-related peptidase 6 (KLK6) and their use in an immunofluorometric assay for free KLK6

We have raised monoclonal antibodies against KLK6 and constructed a 'sandwich' type immunoassay using 8A8G3 as capture and 3H3E9 as tracer antibodies. 8A8G3 bound to one side of KLK6, whereas 3H3E9 probably bound near its catalytic site. The assay did not detect complexed forms of KLK6, indicating that it quantifies only free KLK6 (fKLK6). fKLK6 was higher in serum of patients with ovarian cancer (11.34 μg/l±1.37) than in controls (3.39 μg/l±0.42). The cerebrospinal fluid contained high concentrations of fKLK6 (257-965 μg/l). This assay could facilitate the evaluation of fKLK6 in human diseases.

Predictions for the future of kallikrein-related peptidases in molecular diagnostics

Kallikrein-related peptidases (KLKs) form a cancer-related ensemble of serine proteases. This multigene family hosts the most widely used cancer biomarker that is PSA-KLK3, with millions of tests performed annually worldwide. The present report provides an overview of the biomarker potential of the extended KLK family (KLK1-KLK15) in various disease settings and envisages approaches that could lead to additional KLK-driven applications in future molecular diagnostics. Particular focus is given on the inclusion of KLKs into multifaceted cancer biomarker panels that provide enhanced diagnostic, prognostic and/or predictive accuracy in several human malignancies. Such panels have been described so far for prostate, ovarian, lung and colorectal cancers. The role of KLKs as biomarkers in non-malignant disease settings, such as Alzheimer's disease and multiple sclerosis, is also commented upon. Predictions are given on the challenges and future directions regarding clinically oriented KLK research.

Identification of prefoldin amplification (1q23.3-q24.1) in bladder cancer using comparative genomic hybridization (CGH) arrays of urinary DNA

BACKGROUND

Array-CGH represents a comprehensive tool to discover genomic disease alterations that could potentially be applied to body fluids. In this report, we aimed at applying array-CGH to urinary samples to characterize bladder cancer.

METHODS

Urinary DNA from bladder cancer patients and controls were hybridized on 44K oligonucleotide arrays. Validation analyses of identified regions and candidates included fluorescent in situ hybridization (FISH) and immunohistochemistry in an independent set of bladder tumors spotted on custom-made tissue arrays (n = 181).

RESULTS

Quality control of array-CGH provided high reproducibility in dilution experiments and when comparing reference pools. The most frequent genomic alterations (minimal recurrent regions) among bladder cancer urinary specimens included gains at 1q and 5p, and losses at 10p and 11p. Supervised hierarchical clustering identified the gain at 1q23.3-q24.1 significantly correlated to stage (p = 0.011), and grade (p = 0.002). The amplification and overexpression of Prefoldin (PFND2), a selected candidate mapping to 1q23.3-q24.1, correlated to increasing stage and tumor grade by means of custom-designed and optimized FISH (p = 0.013 and p = 0.023, respectively), and immunohistochemistry (p ≤0.0005 and p = 0.011, respectively), in an independent set of bladder tumors included in tissue arrays. Moreover, PFND2 overexpression was significantly associated with poor disease-specific survival (p ≤0.0005). PFND2 was amplified and overexpressed in bladder tumors belonging to patients providing urinary specimens where 1q23.3q24.1 amplification was detected by array-CGH.

CONCLUSIONS

Genomic profiles of urinary DNA mirrowed bladder tumors. Molecular profiling of urinary DNA using array-CGH contributed to further characterize genomic alterations involved in bladder cancer progression. PFND2 was identified as a tumor stratification and clinical outcome prognostic biomarker for bladder cancer patients.

The physiology and pathobiology of human kallikrein-related peptidase 6 (KLK6)

The human kallikrein-related peptidase 6 (KLK6) gene belongs to the 15-member kallikrein (KLK) gene family mapping to chromosome 19q13.3-13.4. Encoding for an enzyme with trypsin-like properties, KLK6 can degrade components of the extracellular matrix. The successful utilisation of another KLK member (KLK3/PSA) for prostate cancer diagnosis has led many to evaluate KLK6 as a potential biomarker for other cancer and diseased states. The observed dysregulated expression in cancers, neurodegenerative diseases and skin conditions has led to the discovery that KLK6 participates in other cellular pathways including inflammation, receptor activation and regulation of apoptosis. Moreover, the improvements in high-throughput genomics have not only enabled the identification of sequence polymorphisms, but of transcript variants, whose functional significances have yet to be realised. This comprehensive review will summarise the current findings of KLK6 pathophysiology and discuss its potential as a viable biomarker.

Protein-binding microarray analysis of tumor suppressor AP2α target gene specificity

Cheap and massively parallel methods to assess the DNA-binding specificity of transcription factors are actively sought, given their prominent regulatory role in cellular processes and diseases. Here we evaluated the use of protein-binding microarrays (PBM) to probe the association of the tumor suppressor AP2α with 6000 human genomic DNA regulatory sequences. We show that the PBM provides accurate relative binding affinities when compared to quantitative surface plasmon resonance assays. A PBM-based study of human healthy and breast tumor tissue extracts allowed the identification of previously unknown AP2α target genes and it revealed genes whose direct or indirect interactions with AP2α are affected in the diseased tissues. AP2α binding and regulation was confirmed experimentally in human carcinoma cells for novel target genes involved in tumor progression and resistance to chemotherapeutics, providing a molecular interpretation of AP2α role in cancer chemoresistance. Overall, we conclude that this approach provides quantitative and accurate assays of the specificity and activity of tumor suppressor and oncogenic proteins in clinical samples, interfacing genomic and proteomic assays.

Expression and function of the kallikrein-related peptidase 6 in the human melanoma microenvironment

Cutaneous malignant melanoma is an aggressive disease of poor prognosis. Clinical and experimental studies have provided major insight into the pathogenesis of the disease, including the functional interaction between melanoma cells and surrounding keratinocytes, fibroblasts and immune cells. Nevertheless, patients with metastasized melanoma have a very poor prognosis and are largely refractory to clinical therapies. Hence, novel diagnostic tools to monitor melanoma development as well as therapeutic targets are urgently needed. We investigated the expression pattern of the kallikrein-related peptidase 6 (KLK6) in human melanoma tissue sections throughout tumor development. Although, KLK6 was not detectable in tumor cells, we found strong KLK6 protein expression in keratinocytes and stromal cells located adjacent to benign nevi, primary melanomas and cutaneous metastatic lesions, suggesting a paracrine function of extracellular KLK6 during neoplastic transformation and malignant progression. Accordingly, recombinant Klk6 protein significantly induced melanoma cell migration and invasion accompanied by an accelerated intracellular Ca²⁺-flux. We could further demonstrate that KLK6-induced intracellular Ca²⁺-flux and tumor cell invasion critically depends on the protease-activated receptor PAR1. Our data provide experimental evidence that specific inhibition of the KLK6-PAR1 axis may interfere with the deleterious effect of tumor-microenvironment interaction and represent a potential option for translational melanoma research.

Down-regulation of kallikrein-related peptidase 5 (KLK5) expression in breast cancer patients: a biomarker for the differential diagnosis of breast lesions

Background

Kallikrein-related peptidase 5 (KLK5) is a secreted trypsin-like protease of the KLK family, encoded by the KLK5 gene. KLK5 has been found to cleave various extracellular matrix components, as well as to activate several other KLK proteases, triggering the stimulation of tissue microenvironment proteolytic cascades.

Material and Methods

KLK5 expression levels were quantified in 102 cancerous and benign breast tissue specimens, obtained by randomly chosen patients, using RT-qPCR assay. Subsequently, advanced biostatistics were applied in order to analyze the KLK5 expression profile in the two patients' cohorts and also to evaluate its clinical significance for the discrimination of breast tumors.

Results

A statistically significant (p < 0.001) down-regulation of the KLK5 expression levels were observed in the malignant specimens compared to the benign ones. Logistic regression and ROC curve analysis revealed the significant (p < 0.001) and the independent (p < 0.001) value of the KLK5 expression quantification, for the discrimination of the malignant from the benign mammary gland biopsies. Moreover, KLK5 expression levels correlate with the pre-menopausal status (p < 0.005) as well as the ER-negative staining (p = 0.028) of women with breast cancer.

Conclusions

The quantification of KLK5 expression in breast tissue biopsies may be considered as a novel and independent biomarker for the differential diagnosis between malignant and benign tumors of the mammary gland.

Identification and validation of genes involved in cervical tumourigenesis

Background

Cervical cancer is the most common cancer among Indian women. This cancer has well defined pre-cancerous stages and evolves over 10-15 years or more. This study was undertaken to identify differentially expressed genes between normal, dysplastic and invasive cervical cancer.

Materials and methods

A total of 28 invasive cervical cancers, 4 CIN3/CIS, 4 CIN1/CIN2 and 5 Normal cervix samples were studied. We have used microarray technique followed by validation of the significant genes by relative quantitation using Taqman Low Density Array Real Time PCR. Immunohistochemistry was used to study the protein expression of MMP3, UBE2C and p16 in normal, dysplasia and cancers of the cervix. The effect of a dominant negative UBE2C on the growth of the SiHa cells was assessed using a MTT assay.

Results

Our study, for the first time, has identified 20 genes to be up-regulated and 14 down-regulated in cervical cancers and 5 up-regulated in CIN3. In addition, 26 genes identified by other studies, as to playing a role in cervical cancer, were also confirmed in our study. UBE2C, CCNB1, CCNB2, PLOD2, NUP210, MELK, CDC20 genes were overexpressed in tumours and in CIN3/CIS relative to both Normal and CIN1/CIN2, suggesting that they could have a role to play in the early phase of tumorigenesis. IL8, INDO, ISG15, ISG20, AGRN, DTXL, MMP1, MMP3, CCL18, TOP2A AND STAT1 were found to be upregulated in tumours. Using Immunohistochemistry, we showed over-expression of MMP3, UBE2C and p16 in cancers compared to normal cervical epithelium and varying grades of dysplasia. A dominant negative UBE2C was found to produce growth inhibition in SiHa cells, which over-expresses UBE2C 4 fold more than HEK293 cells.

Conclusions

Several novel genes were found to be differentially expressed in cervical cancer. MMP3, UBE2C and p16 protein overexpression in cervical cancers was confirmed by immunohistochemistry. These will need to be validated further in a larger series of samples. UBE2C could be evaluated further to assess its potential as a therapeutic target in cervical cancer.

Genomic instability and copy-number heterogeneity of chromosome 19q, including the kallikrein locus, in ovarian carcinomas

Many tissue kallikrein (KLK) genes and proteins are candidate diagnostic, prognostic and predictive biomarkers for ovarian cancer (OCa). We previously demonstrated that the KLK locus (19q13.3/4) is subject to copy-number gains and structural rearrangements in a pilot study of cell lines and ovarian cancer primary tissues, shown to overexpress KLK gene family members. To determine the overall frequency of genomic instability and copy-number changes, a retrospective study was conducted using formalin-fixed paraffin embedded (FFPE) tissues. Eighty-one chemotherapy naïve serous OCas were examined using 3-colour fluorescence in situ hybridization (FISH) to identify structural and numerical changes on 19q, including the KLK locus; in addition to immunohistochemistry (IHC) for KLK6, which has been shown to be overexpressed in OCa. The KLK locus was subject to copy-number changes in ∼83% of cases: net gain in 51%, net loss in 30% and amplified in 2%; and found to be chromosomally unstable (p < 0.001). All cases showed a wide range of immuoreactivity for KLK6 by IHC. Although no strong correlation could be found with copy-number, the latter was contributing factor to the observed KLK6 protein overexpression. Moreover, univariate and multivariate analyses showed an association between the net loss of the KLK locus and longer disease-free survival. Interestingly, FISH analyses indicated that chromosome 19q was subjected to structural rearrangement in 62% of cases and was significantly correlated to tumor grade (p < 0.001). We conclude that numerical and structural aberrations of chromosome 19q, affect genes including the KLK gene members, may contribute to ovarian carcinoma progression and aggressiveness.

LY6K is a novel molecular target in bladder cancer on basis of integrate genome-wide profiling

Background:

The aim of this study is to find a novel molecular target based on chromosomal alteration and array-based gene expression analyses in bladder cancer (BC). We investigated a cancer testis antigen, LY6K, which is located on chromosome 8q24.3.

Methods:

Five BC cell lines were subjected to high-resolution array-comparative genomic hybridisation with 244 000 probes. The expression levels of LY6K mRNA were evaluated in BC cell lines and clinical BC specimens by real-time reverse transcription–PCR. The cell lines were subjected to fluorescence in situ hybridisation of LY6K. Cell viability was evaluated by cell growth, wound healing, and matrigel invasion assays.

Results:

Typical gained loci (P<0.0001) at 6p21.33-p21.32, 8q24.3, 9q34.13, 11q13.1-q14.1, 12q13.12-q13.13, 16p13.3, and 20q11.21-q13.33 were observed in all of the cell lines. We focused on 8q24.3 locus where LY6K gene harbours, and it was the top upregulated one in the gene profile from the BC cell line. LY6K mRNA expression was significantly higher in 91 BCs than in 37 normal bladder epitheliums (P<0.0001). Fluorescence in situ hybridisation validated that the high LY6K mRNA expression was due to gene amplification in the region where the gene harbours. Cell viability assays demonstrated that significant inhibitions of cell growth, migration, and invasion occured in LY6K knock down BC cell lines; converse phenomena were observed in a stable LY6K transfectant; and LY6K knockdown of the transfectant retrieved the original phenotype from the LY6K transfectant.

Conclusion:

Upregulation of the oncogenic LY6K gene located on the gained locus at 8q24.3 may contribute BC development.

Kallikreins on steroids: structure, function, and hormonal regulation of prostate-specific antigen and the extended kallikrein locus

The 15 members of the kallikrein-related serine peptidase (KLK) family have diverse tissue-specific expression profiles and putative proteolytic functions. The kallikrein family is also emerging as a rich source of disease biomarkers with KLK3, commonly known as prostate-specific antigen, being the current serum biomarker for prostate cancer. The kallikrein locus is also notable because it is extraordinarily responsive to steroids and other hormones. Indeed, at least 14 functional hormone response elements have been identified in the kallikrein locus. A more comprehensive understanding of the transcriptional regulation of kallikreins may help the field make more informed hypotheses about the physiological functions of kallikreins and their effectiveness as biomarkers. In this review, we describe the organization of the kallikrein locus and the structure of kallikrein genes and proteins. We also focus on the transcriptional regulation of kallikreins by androgens, progestins, glucocorticoids, mineralocorticoids, estrogens, and other hormones in animal models and human prostate, breast, and reproductive tract tissues. The interaction of the androgen receptor with androgen response elements in the promoter and enhancer of KLK2 and KLK3 is also summarized in detail. There is evidence that all kallikreins are regulated by multiple nuclear receptors. Yet, apart from KLK2 and KLK3, it is not clear whether all kallikreins are direct transcriptional targets. Therefore, we argue that gaining more detailed information about the mechanisms that regulate kallikrein expression should be a priority of future studies and that the kallikrein locus will continue to be an important model in the era of genome-wide analyses.

Prognostic value and biological role of the kallikrein-related peptidases in human malignancies

Cancer is a substantial health problem for the populations of the Western world. The discovery of new molecular biomarkers for diagnosis, prognosis and monitoring patients' response to therapy can aid in combating this complicated disease. The human kallikrein-related peptidases (human tissue kallikreins [KLKs]) are encoded by a continuous multigene family, located on chromosomal region 19q13.3-4. KLK3 (prostate-specific antigen) is the most efficient cancer biomarker ever employed. KLK genes are expressed abnormally in various malignancies, where they affect cancer-cell growth and metastasis. Their deregulated expression pattern, often associated with various clinicopathological characteristics of cancer patients, can be exploited, solely or within multiparametric panels, as a prognostic biomarker. Recent data illustrate that discernible molecular modulations of KLKs, occurring as a result of cancer cells' treatment with antitumor agents, may serve as new potential biomarkers, possibly predicting patients' treatment response. It is believed that KLKs might be employed in future clinical practice as novel and effective tumor markers.

Dysregulation of kallikrein-related peptidases in renal cell carcinoma: potential targets of miRNAs

Renal cell carcinoma (RCC) accounts for 3% of all adult malignancies and currently no diagnostic marker exists. Kallikrein-related peptidases (KLKs) have been implicated in numerous cancers including ovarian, prostate, and breast carcinoma. KLKs 5, 6, 10, and 11 have decreased expression in RCC when compared to normal kidney tissue. Our bioinformatic analysis indicated that theKLK 1,6, and7genes have decreased expression in RCC. We experimentally verified these results and found that decreased expression ofKLKs 1and3were significantly associated with the clear cell RCC subtype (p<0.001). An analysis of miRNAs differentially expressed in RCC showed that 61 of the 117 miRNAs that were reported to be dysregulated in RCC were predicted to target KLKs. We experimentally validated two targets using two independent approaches. Transfection of miR-224 into HEK-293 cells resulted in decreased KLK1 protein levels. A luciferase assay demonstrated that hsa-let-7f can target KLK10 in the RCC cell line ACHN. Our results, showing differential expression of KLKs in RCC, suggest that KLKs could be novel diagnostic markers for RCC and that their dysregulation could be under miRNA control. The observation that KLKs could represent targets for miRNAs suggests a post-transcriptional regulatory mechanism with possible future therapeutic applications.

Three dysregulated miRNAs control kallikrein 10 expression and cell proliferation in ovarian cancer

BACKGROUND

Kallikrein-related peptidases (KLKs) are a family of serine proteases that have been shown to be dysregulated in several malignancies including ovarian cancer. The control of kallikrein genes and their physiological function in cancer is not well understood. We hypothesized that microRNAs (miRNAs) represent a novel mechanism for post-transcriptional control of KLK expression in cancer.

METHODS

We first analysed miRNA expression in ovarian cancer in silico. A total of 98 miRNAs were reported to have altered expression in ovarian cancer. Three of these miRNAs were predicted to target KLK10. We experimentally verified the predicted miR-KLK10 interaction using two independent techniques, a luciferase assay with a construct containing the KLK10 3' untranslated region (UTR), pMIR-KLK10, and measuring KLK10 protein levels after transfection with miRNA.

RESULTS

When we co-transfected cells with pMIR-KLK10 and either let-7f, miR-224, or mR-516a, we saw decreased luciferase signal, suggesting that these miRNAs can target KLK10. We then examined the effect of these three miRNAs on KLK10 protein expression and cell growth. Transfection of all miRNAs, let-7f, miR-224, and miR-516a led to a decrease in protein expression and cellular growth. This effect was shown to be dose dependent. The KLK10 protein levels were partially restored by co-transfecting let-7f and its inhibitor. In addition, there was a slight decrease in KLK10 mRNA expression after transfection with let-7f.

CONCLUSION

Our results confirm that KLKs can be targeted by more than one miRNA. Increased expression of certain miRNAs in ovarian cancer can lead to decreased KLK protein expression and subsequently have a negative effect on cell proliferation. This dose-dependent effect suggests that a 'tweaking' or 'fine-tuning' mechanism exists in which the expression of one KLK can be controlled by multiple miRNAs. These data together suggest that miRNA may be used as potential therapeutic options and further studies are required.

Quantitative Analysis of Human Kallikrein 5 (KLK5) Expression in Prostate Needle Biopsies: An Independent Cancer Biomarker

Background: Kallikrein 5 (KLK5), a recently cloned member of the kallikrein family, codes for the secreted protein KLK5. Active KLK5 protein has a trypsin activity, and the expression of KLK5 gene seems to be regulated by steroid hormones. We performed an expression analysis and clinical evaluation of the KLK5 gene, at the mRNA level, in prostate needle biopsies.

Methods: We examined KLK5 mRNA concentrations in 103 prostate tissue specimens. After testing of RNA quality, cDNA was prepared by reverse transcription. A highly sensitive quantitative real-time PCR (qRT-PCR) method for KLK5 mRNA quantification was developed using the SYBR Green chemistry. GAPDH was used as a housekeeping gene.

Results: Specimens from patients with benign prostatic hyperplasia (BPH) showed higher levels of KLK5 mRNA expression than those from patients with prostate cancer (PCa) (P = 0.024). ROC analysis demonstrated that KLK5 expression had significant discriminatory value between BPH and PCa (AUC 0.64; P = 0.016). KLK5 mRNA expression showed a statistically significant negative correlation with the total PSA serum concentration in the PCa patients (P = 0.003). Early-stage tumors showed higher KLK5 expression than late-stage ones (P = 0.014), whereas KLK5 expression was negatively correlated to Gleason score (P = 0.005).

Conclusions: KLK5 mRNA, analyzed by quantitative PCR in prostate needle biopsies, could be an independent biomarker for the differential diagnosis and prognosis in prostate cancer.

Parallel underexpression of kallikrein 5 and kallikrein 7 mRNA in breast malignancies

Kallikrein (KLK) 5 and KLK7 were reported to be overexpressed in several cancers, but underexpressed in prostate and breast cancers. However, the expression levels of KLK5 and KLK7 in benign breast tissues and metastases, and the relationship between KLK5 and KLK7, have not been reported. In addition, the value of KLK5 and KLK7 in the diagnosis and prognosis prediction of breast cancer patients is far from clear. To further determine their role and clinical significance in breast cancer and to explore the relationship between KLK5 and KLK7, the mRNA levels of KLK5 and KLK7 in normal breast tissues, benign breast tissues, primary tumors, and lymph node metastases were detected by real-time reverse transcription-polymerase chain reaction and microarray. The relationship between KLK5 and KLK7 expression and clinicopathological parameters, and the correlation between the mRNA levels of KLK5 and KLK7 as well as the 5'-uncoding regions of KLK5 and KLK7 were analyzed. The mRNA levels of KLK5 and KLK7 were both downregulated in breast cancers relative to normal and benign tissues, and downregulated in metastases compared to primary cancers. Underexpression of KLK5 and KLK7 was correlated with postmenopausal status and positive estrogen receptor status. The mRNA levels of KLK5 and KLK7 were positively correlated in breast malignancies. Moreover, four homologous sequences and 10 transcription factors as potential regulators were found on the control regions of both KLK5 and KLK7. Thus, KLK5 and KLK7 were underexpressed in parallel, potentially with the same regulation pathways, in breast malignancies, which might contribute to the carcinogenesis and development of breast cancer. They are potential biomarkers for breast cancer.

Molecular Pathology of the Genitourinary Tract: Prostate and Bladder

The knowledge of cellular mechanisms in tumors of the prostate and bladder has grown exponentially. Molecular technologies have led to the discovery of TMPRSS2 in prostate cancer and the molecular pathways distinguishing low- and high-grade urothelial neoplasms. UroVysion with fluorescence in situ hybridization is already commonplace as an adjunct to cytologic diagnosis of urothelial neoplasms. This trend portends the future in which classification and diagnosis of tumors of the prostate and bladder through morphologic analysis will be supplemented by molecular information correlating with prognosis and targeted therapy. This article outlines tumor molecular pathology of the prostate and bladder encompassing current genomic, epigenomic, and proteonomic findings.

Impact of cytogenetic and genomic aberrations of the kallikrein locus in ovarian cancer

The tissue kallikrein (KLK) genes are a new source for biomarkers in ovarian cancer. However, there has been no systematic analysis of copy number and structural rearrangements related to their protein expression. Chromosomal rearrangements and copy number changes of the KLK region were studied by FISH with protein levels measured by ELISA. Ovarian cancer and cell lines revealed the KLK region was subject to copy number imbalances or involved in unbalanced translocations and were associated with increased protein expression of KLKs 5, 6, 7, 8, 9, 10 and 11. In this initial study, we introduce the potential for long-range chromosomal effects and copy number as a mechanism for the previously reported aberrant expression of many KLK genes in ovarian cancers.

microRNAs: a new frontier in kallikrein research

microRNAs (miRNAs) are a recently discovered class of small non-coding RNAs that regulate gene expression. Rapidly accumulating evidence has revealed that miRNAs are associated with cancer. The human tissue kalli-krein gene family is the largest contiguous family of proteases in the human genome, containing 15 genes. Many kallikreins have been reported as potential tumor markers. In this review, recent bioinformatics and experimental evidence is presented indicating that kallikreins are potential miRNA targets. The available experimental approaches to investigate these interactions and the potential diagnostic and therapeutic applications are also discussed. miRNAs represent a possible regulatory mechanism for controlling kallikrein expression at the post-transcriptional level. Many miRNAs were predicted to target kallikreins and a single miRNA can target more than one kallikrein. Recent evidence suggests that miRNAs can also exert ‘quantitative’ control of kallikreins by utilizing multiple targeting sites in the kallikrein mRNA. More research is needed to experimentally verify the in silico predictions and to investigate the possible role in tumor initiation and/or progression.

Activation of hepatocyte growth factor activator zymogen (pro-HGFA) by human kallikrein 1-related peptidases

Hepatocyte growth factor activator (HGFA) is a serine protease and a potent activator of prohepatocyte growth factor/scatter factor (pro-HGF/SF), a multifunctional growth factor that is critically involved in tissue morphogenesis, regeneration, and tumor progression. HGFA circulates as a zymogen (pro-HGFA) and is activated in response to tissue injury. Although thrombin is considered to be an activator of pro-HGFA, alternative pro-HGFA activation pathways in tumor microenvironments remain to be identified. In this study, we examined the effects of kallikrein 1-related peptidases (KLKs), a family of extracellular serine proteases, on the activation of pro-HGFA. Among the KLKs examined (KLK2, KLK3, KLK4 and KLK5), we identified KLK4 and KLK5 as novel activators of pro-HGFA. Using N-terminal sequencing, the cleavage site was identified as the normal processing site, Arg407-Ile408. The activation of pro-HGFA by KLK5 required a negatively charged substance such as dextran sulfate, whereas KLK4 could process pro-HGFA without dextran sulfate. KLK5 showed more efficient pro-HGFA processing than KLK4, and was expressed in 50% (13/25) of the tumor cell lines examined. HGFA processed by these KLKs efficiently activated pro-HGF/SF, and led to cellular scattering and invasion in vitro. The activities of both KLK4 and KLK5 were strongly inhibited by HGFA inhibitor type 1, an integral membrane Kunitz-type serine protease inhibitor that inhibits HGFA and other pro-HGF/SF-activating proteases. These data suggest that KLK4 and KLK5 mediate HGFA-induced activation of pro-HGF/SF within tumor tissue, which may thereafter trigger a series of events leading to tumor progression via the MET receptor.