Kallikrein-related peptidase 4 (KLK4) mRNA predicts short-term relapse in colorectal adenocarcinoma patients

High Intratumoral i-tRF-GlyGCC Expression Predicts Short-Term Relapse and Poor Overall Survival of Colorectal Cancer Patients, Independent of the TNM Stage

Colorectal cancer (CRC), one of the most prevalent types of cancer, requires the discovery of new tumor biomarkers for accurate patient prognosis. In this work, the prognostic value of the tRNA fragment i-tRF-Gly^GCC in CRC was examined. Total RNA extraction from 211 CRC patient cancer tissue specimens and 83 adjacent normal tissues was conducted. Each RNA extract was subjected to in vitro polyadenylation and reverse transcription. A real-time quantitative PCR assay was used to quantify i-tRF-Gly^GCC in all samples. Extensive biostatics analysis showed that i-tRF-Gly^GCC levels in CRC tissues were significantly lower than in matched normal colorectal tissues. Additionally, the disease-free survival (DFS) and overall survival (OS) time intervals were considerably shorter in CRC patients with high i-tRF-Gly^GCC expression. i-tRF-Gly^GCC expression maintained its prognostic value independently of other established prognostic factors, as shown by the multivariate Cox regression analysis. Additionally, survival analysis after TNM stage stratification revealed that higher i-tRF-Gly^GCC levels were linked to shorter DFS time intervals in patients with TNM stage II tumors, as well as an increased probability of having a worse OS for patients in TNM stage II. In conclusion, i-tRF-Gly^GCC has the potential to be a useful molecular tissue biomarker in CRC, independent of other clinicopathological variables.

MicroRNA-675-5p Overexpression Is an Independent Prognostic Molecular Biomarker of Short-Term Relapse and Poor Overall Survival in Colorectal Cancer

Colorectal cancer (CRC) is the main cause of cancer-related deaths globally, highlighting the importance of accurate biomarkers for early detection and accurate prognosis. MicroRNAs (miRNAs) have emerged as effective cancer biomarkers. The aim of this study was to investigate the prognostic potential of miR-675-5p as a molecular prognostic biomarker in CRC. For this reason, a quantitative PCR assay was developed and applied to determine miR-675-5p expression in cDNAs from 218 primary CRC and 90 paired normal colorectal tissue samples. To assess the significance of miR-675-5p expression and its association with patient outcome, extensive biostatistical analysis was performed. miR-675-5p expression was found to be significantly downregulated in CRC tissue samples compared to that in adjacent normal colorectal tissues. Moreover, high miR-675-5p expression was associated with shorter disease-free (DFS) and overall survival (OS) in CRC patients, while it maintained its unfavorable prognostic value independently of other established prognostic factors. Furthermore, TNM stage stratification demonstrated that higher miR-675-5p levels were associated with shorter DFS and OS intervals, particularly in patients with CRC of TNM stage II or III. In conclusion, our findings suggest that miR-675-5p overexpression constitutes a promising molecular biomarker of unfavorable prognosis in CRC, independent of other established prognostic factors, including TNM staging.

5-Hydroxymethylcytosine signature in circulating cell-free DNA as a potential diagnostic factor for early-stage colorectal cancer and precancerous adenoma

Approximately 85% colorectal cancers (CRCs) are thought to evolve through the adenoma‐to‐carcinoma sequence associated with specific molecular alterations, including the 5‐hydroxymethylcytosine (5hmC) signature in circulating cell‐free DNA (cfDNA). To explore colorectal disease progression and evaluate the use of cfDNA as a potential diagnostic factor for CRC screening, here, we performed genome‐wide 5hmC profiling in plasma cfDNA and tissue genomic DNA (gDNA) acquired from 101 samples (63 plasma and 38 tissues), collected from 21 early‐stage CRC patients, 21 AD patients, and 21 healthy controls (HC). The gDNA and cfDNA 5hmC signatures identified in gene bodies and promoter regions in CRC and AD groups were compared with those in HC group. All the differential 5hmC‐modified regions (DhMRs) were gathered into four clusters: Disease‐enriched, AD‐enriched, Disease‐lost, and AD‐lost, with no overlap. AD‐related clusters, AD‐enriched and AD‐lost, displayed the unique 5hmC signals in AD patients. Disease‐enriched and Disease‐lost clusters indicated the general 5hmC changes when colorectal lesions occurred. Cancer patients with a confirmable adenoma history segmentally gathered in AD‐enriched clusters. KEGG functional enrichment and GO analyses determined distinct differential 5hmC‐modified profiles in cfDNA of HC individuals, AD, and CRC patients. All patients had comprehensive 5hmC signatures where Disease‐enriched and Disease‐lost DhMR clusters demonstrated similar epigenetic modifications, while AD‐enriched and AD‐lost DhMR clusters indicated complicated subpopulations in adenoma. Analysis of CRC patients with adenoma history showed exclusive 5hmC‐gain characteristics, consistent with the ‘parallel’ evolution hypothesis in adenoma, either developed through the adenoma‐to‐carcinoma sequence or not. These findings deepen our understanding of colorectal disease and suggest that the 5hmC modifications of different pathological subtypes (cancer patients with or without adenoma history) could be used to screen early‐stage CRC and assess adenoma malignancy with large‐scale follow‐up studies in the future.

Low expression of miR-20b-5p indicates favorable prognosis in laryngeal squamous cell carcinoma, especially in patients with non-infiltrated regional lymph nodes

PURPOSE

Tumor recurrence and distant metastasis are very common in laryngeal squamous cell carcinoma (LSCC). In this study, we examined the potential prognostic value of microRNA-20b-5p (miR-20b-5p), a component of the tumor-related miR-106a/363 cluster.

MATERIALS AND METHODS

Total RNA was purified from 105 tissue specimens resected from patients having undergone surgical treatment for primary LSCC. After in vitro polyadenylation and reverse transcription, a sensitive real-time quantitative polymerase chain reaction (qPCR) methodology was applied for the relative quantification of miR-20b-5p levels. Then, we proceeded with biostatistical analysis, seeking to assess the prognostic value of miR-20b-5p expression in LSCC.

RESULTS

miR-20b-5p positivity constitutes a predictor of inferior DFS and OS in LSCC (P < 0.001 and P = 0.002, respectively). The significant prognostic value of miR-20b-5p expression status seems to be independent of tumor size, histological grade, and TNM stage, as revealed by the multivariate bootstrap Cox regression analysis. Kaplan-Meier survival analysis showed also that miR-20b-5p expression status can stratify LSCC patients with non-infiltrated regional lymph nodes (N0) into two subgroups with distinct prognosis (P = 0.004 and P = 0.004, respectively).

CONCLUSIONS

The miR-20b-5p expression status is a promising molecular tissue biomarker in LSCC, with an independent prognostic value, and thus merits further validation in larger cohorts of patients.

DNA methylation in Hepatoblastoma-a literature review

Hepatoblastoma (HB) is the most common malignant liver tumor in children. Abnormal activation of the Wnt/β-catenin signaling pathway plays an important role in the formation and development of HB. Genes in HB show a global hypomethylation change, accompanied by hypermethylation of specific tumor suppressor genes (TSGs). This article reviews the hypermethylation changes in several TSGs, such as RASSF1A, SOCS1, APC, HHIP, and P16, and analyzes the pathways and mechanisms of TSGs regulating gene expression. The role of the methylation-regulating enzymes DNA methyltransferases (DNMTs) and ten-eleven translocation (TET) family members enzymes in the methylation changes of HB was analyzed, and it was speculated that the occurrence of HB is partly due to the obstruction of liver differentiation in the early stage of differentiation. The origin cells may be incompletely differentiated hepatocytes remaining in the liver of children after birth. Therefore, further studying the role of methylation regulating enzymes in methylation changes in HB is a promising future research direction.

Biomarker implication of kallikrein-related peptidases as prognostic tissue substrates of poor survival in colorectal cancer

Background

Recent studies have demonstrated that the kallikrein and kallikrein-related peptidases (KLKs) exhibit aberrant expression in patients with colorectal cancer (CRC) and might be considered as potential prognostic biomarkers of CRC. However, inconsistent findings have been reported, which promote us to summarize the global prognostic roles of KLKs for survival in CRC patients.

Methods

Eligible published studies were identified by searching electronic databases with several search strategies. The patients’ baseline characteristics and survival results were extracted from enrolled studies and pooled as combined hazard ratio (HR) with 95% confidence interval (95% CI) to estimate the effect size.

Results

A total of 25 and 22 eligible studies were included in the meta-analysis to evaluate the prognostic roles of KLKs on overall survival (OS) and disease-free survival (DFS), respectively. KLKs overexpression was significantly associated with worse OS (pooled HR = 1.43, 95% CI 1.27–1.60, P < 0.001) and short DFS (pooled HR = 1.35, 95% CI 1.21–1.51, P < 0.001). Importantly, subgroup and meta-regression analyses revealed the survival differences among different races and detection methods of KLKs. Furthermore, several specific members of KLKs were identified to be more significantly related to worse OS and DFS compared with other members.

Conclusion

The present study demonstrated that KLKs may have the potential to serve as promising biomarkers to monitor CRC prognosis and progression. The promising results concerning the utility of KLKs in clinical practice encourage the further investigation of their clinical utility applicability as tumor markers of CRC.

Circular RNA Circ_0025033 Promotes the Evolvement of Ovarian Cancer Through the Regulation of miR-330-5p/KLK4 Axis

Background

Circular RNAs (circRNAs) are significant molecular targets in various types of human cancers. The functional mechanism of circRNA_0025033 (circ_0025033) in ovarian cancer (OC) was discussed in the current report.

Methods

The quantitative real-time polymerase chain reaction (qRT-PCR) was used for determining the circ_0025033 and microRNA-330-5p (miR-330-5p) levels. Cell Counting Kit-8 (CCK-8) and transwell assays were separately exploited to analyze cell viability and migration/invasion. Cell apoptosis was assessed using flow cytometry. The protein levels of epithelial–mesenchymal transition (EMT)-related makers and kallikrein-related peptidase 4 (KLK4) were measured by Western blotting. The target combination was confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) and RNA pull-down assays. And the effect of circ_0025033 on OC in vivo was explored via xenograft tumor assay.

Results

Circ_0025033 was overexpressed in OC tissues and cells. Circ_0025033 knockdown inhibited OC cell viability, migration, invasion and EMT while expedited apoptosis. MiR-330-5p was a target of circ_0025033 and circ_0025033 regulated OC cellular behaviors by sequestering miR-330-5p. Moreover, miR-330-5p targeted KLK4 and circ_0025033 affected the KLK4 expression by sponging miR-330-5p. And miR-330-5p functioned as a tumor inhibitor in OC via targeting KLK4. In vivo, circ_0025033 promoted OC growth by the miR-330-5p/KLK4 axis.

Conclusion

This study demonstrated that circ_0025033 contributed to the progression of OC via the miR-330-5p/KLK4 axis and might be a candidate target in the identification and treatment of OC.

MicroRNA-378-3p/5p represses proliferation and induces apoptosis of oral squamous carcinoma cells via targeting KLK4

Oral squamous cell carcinoma (OSCC) is one of the most common types of head and neck neoplasm. Down-regulation of hsa-microRNA-378 (miR-378) has been proved in OSCC tissues, suggesting that miR-378 might play crucial roles in the progression of OSCC. The present study aimed to evaluate the effect of miR-378-3p/5p on the proliferation and apoptosis of OSCC in vitro and in vivo. According to the results, lentivirus-mediated overexpression of miR-378 lowered the colony formation efficiency, blocked cell cycle progression, and decreased the percentage of Ki-67 positive cells, whereas knockdown of miR-378-3p/5p led to the opposite results. Furthermore, the apoptosis of OSCC cells was induced by the overexpression of miR-378 as evidenced by decreasing Bcl-2/Bax ratio, increasing cleaved caspase-9, cleaved caspase-3, and cleaved PARP levels, and promoting the release of cytochrome c into the cytoplasm. However, the above results were reversed by miR-378-3p/5p silencing. In addition, the overexpression of miR-378 inhibited the activation of PI3K/AKT signalling pathway. Conversely, miR-378-3p/5p knockdown resulted in the inactivation of PI3K/AKT signalling pathway. Mechanically, we validated that miR-378-3p/5p could target kallikrein-related peptidase 4 (KLK4), and enforced overexpression of KLK4 counteracted miR-378 overexpression-induced apoptosis. Finally, tumourigenesis in nude mice was suppressed by the overexpression of miR-378, which was promoted by miR-378-3p/5p silencing. Taken together, these results suggest that miR-378 may be a potential target in the diagnoses and treatment of OSCC.

Uncovering the clinical impact of kallikrein-related peptidase 5 (KLK5) mRNA expression in the colorectal adenoma-carcinoma sequence

Background Kallikrein-related peptidases (KLKs) are a subgroup of serine proteases located on chromosome 19q13.3. Most KLKs have been extensively studied as potential biomarkers for several carcinomas and other diseases. KLK5 was originally identified from a keratinocyte library, and its enzyme was purified from the stratum corneum of human skin. KLK5 was shown to be differentially expressed in a variety of endocrine tumors, although it is not as yet examined widely in colorectal cancer (CRC). Methods In this study, we quantitatively assessed the mRNA expression status of KLK5 in 197 colorectal tissues from 133 patients (70 cancerous and their paired normal colonic mucosa for 64 of them, as well as 63 colorectal adenomas) by quantitative real-time PCR (qPCR) using TaqMan probes. Statistical analysis evaluated the results. Results It was shown that KLK5 expression is reduced following the histologically non-cancerous-adenoma sequence (p<0.001), whereas it is increased during the sequence adenoma-carcinoma (p<0.001). Furthermore, KLK5 positive expression is associated with positive nodal status (p=0.022), advanced tumor stage (p=0.038) and high histological grade (p=0.033). Cox univariate analysis revealed that KLK5 positive expression is associated with disease-free survival (DFS) (p=0.028) and overall survival (OS) of patients (p=0.048). Kaplan-Meyer survival models showed that patients with positive KLK5 expression have lower DFS (p=0.009) and OS (p=0.019). Receiver operating characteristic (ROC) analysis demonstrated for first time that KLK5 expression had significant discriminatory values between cancer and adenoma tissues (area under the curve [AUC] 0.77; 95% confidence interval [CI]=0.69-0.85, p=0.03). Conclusions KLK5 mRNA expression may be useful for the differentiation of CRC from colorectal adenoma and represents a potential unfavorable prognostic biomarker for CRC.

Expression of vimentin (VIM) and metastasis-associated 1 (MTA1) protein in laryngeal squamous cell carcinoma are associated with prognostic outcome of patients

PURPOSE

Laryngeal squamous cell carcinoma (LSCC), a common type of head and neck cancer, is associated with high rates of metastasis and recurrence. In this study, we investigated the potential combinatorial prognostic value of NOTCH1, Vimentin (VIM), and Metastasis-associated 1 (MTA1) protein in LSCC, using immunohistochemistry.

MATERIALS AND METHODS

Tissue specimens from 69 patients with LSCC were immunohistochemically evaluated for the protein expression of NOTCH1, VIM, and MTA1. Then, biostatistical analysis was performed, in order to assess the prognostic value of the expression of each one of these proteins.

RESULTS

NOTCH1 expression status was not a significant prognosticator in LSCC, as shown in Kaplan-Meier survival analysis. On the contrary, both VIM and MTA1 seem to have an important prognostic potential, independently of TNM staging and histological grade of the tumor. In fact, positive VIM expression was shown to predict patients' relapse and poor outcome regarding patients' overall survival, in contrast with MTA1, the positive expression of which predicts higher disease-free survival (DFS) and overall survival (OS) rates in LSCC.

CONCLUSIONS

VIM and MTA1 constitute potential tumor biomarkers in LSCC and could be integrated into a multiparametric prognostic model. Undoubtedly, their prognostic value needs further validation in larger cohorts of LSCC patients.

Kallikrein-related peptidases and associated microRNAs as promising prognostic biomarkers in gastrointestinal malignancies

Gastrointestinal (GI) malignancies represent a wide spectrum of diseases of the GI tract and its accessory digestive organs, including esophageal (EC), gastric (GC), hepatocellular, pancreatic (PC) and colorectal cancers (CRC). Malignancies of the GI system are responsible for nearly 30% of cancer-related morbidity and approximately 40% of cancer-related mortality, worldwide. For this reason, the discovery of novel prognostic biomarkers that can efficiently provide a better prognosis, risk assessment and prediction of treatment response is an imperative need. Human kallikrein-related peptidases (KLKs) are a subgroup of trypsin and chymotrypsin-like serine peptidases that have emerged as promising prognosticators for many human types of cancer, being aberrantly expressed in cancerous tissues. The aberrant expression of KLKs in human malignancies is often regulated by KLK/microRNAs (miRNAs) interactions, as many miRNAs have been found to target KLKs and therefore alter their expression levels. The biomarker utility of KLKs has been elucidated not only in endocrine-related human malignancies, including those of the prostate and breast, but also in GI malignancies. The main purpose of this review is to summarize the existing information regarding the prognostic significance of KLKs in major types of GI malignancies and highlight the regulatory role of miRNAs on the expression levels of KLKs in these types of cancer.

Quantitative analysis and study of the mRNA expression levels of apoptotic genes BCL2, BAX and BCL2L12 in the articular cartilage of an animal model of osteoarthritis

Background

Given that apoptosis of chondrocytes is one of the most important factors related to the pathogenesis of osteoarthritis (OA), the recent research interest adds progress not only to the knowledge of the molecular signals that mediate apoptosis but also to find new therapeutic targets. This study attempts to investigate the differential expression of BCL2 family genes in the articular cartilage of an experimental animal model of OA.

Methods

In total, 26 New Zealand white rabbits underwent an anterior cruciate ligament transaction, 26 more were subjected to a placebo surgery and 18 specimens constituted the control non-operated group. Thirteen weeks later, samples of cartilage from the osteoarthritic and non-osteoarthritic knees were collected and subjected to analysis of the BCL2, BAX and BCL2L12 gene expression at the mRNA level.

Results

Installed osteoarthritic alterations of varied intensity and of grade 1 up to grade 5, were confirmed according to the OARSI system. Contrary to the physiologically healthy samples, in the osteoarthritic samples the mRNA expression levels of BAX and BCL2L12 genes were found significantly upregulated by signals which can activate apoptosis. However, the difference between BCL2 mRNA expression levels in healthy and osteoarthritic samples was not supported statistically.

Conclusions

Since apoptosis is the main feature of the cartilage degeneration in OA, the effective inhibition of apoptosis of chondrocytes can provide novel and interesting therapeutic strategies for the treatment of OA. Therefore, BAX and BCL2L12 are highlighted as potential therapeutic targets in OA.

Non-coding RNAs: the riddle of the transcriptome and their perspectives in cancer

Non-coding RNAs (ncRNAs) constitute a heterogeneous group of RNA molecules in terms of biogenesis, biological function as well as length and structure. These biological molecules have gained attention recently as a potentially crucial layer of tumor cell progression or regulation. ncRNAs are expressed in a broad spectrum of tumors, and they play an important role not only in maintaining but also in promoting cancer development and progression. Recent discoveries have revealed that ncRNAs may act as key signal transduction mediators in tumor signaling pathways by interacting with RNA or proteins. These results reinforce the hypothesis, that ncRNAs constitute therapeutic targets, and point out their clinical potential as stratification markers. The major purpose of this review is to mention the emergence of the importance of ncRNAs, as molecules which are correlated with cancer, and to discuss their clinical implicit as prognostic diagnostic indicators, biomarkers, and therapeutic targets.

Alternative Splicing Detection Tool-a novel PERL algorithm for sensitive detection of splicing events, based on next-generation sequencing data analysis

Next-generation sequencing (NGS) can provide researchers with high impact information regarding alternative splice variants or transcript identifications. However, the enormous amount of data acquired from NGS platforms make the analysis of alternative splicing events hard to accomplish. For this reason, we designed the "Alternative Splicing Detection Tool" (ASDT), an algorithm that is capable of identifying alternative splicing events, including novel ones from high-throughput NGS data. ASDT is available as a PERL script at http://aias.biol.uoa.gr/~mtheo and can be executed on any system with PERL installed. In addition to the detection of annotated and novel alternative splicing events from high-throughput NGS data, ASDT can also analyze the intronic regions of genes, thus enabling the detection of novel cryptic exons residing in annotated introns, extensions of previously annotated exons, or even intron retentions. Consequently, ASDT demonstrates many innovative and unique features that can efficiently contribute to alternative splicing analysis of NGS data.

Identification of methylation sites and signature genes with prognostic value for luminal breast cancer

Background

Robust and precise molecular prognostic predictors for luminal breast cancer are required. This study aimed to identify key methylation sites in luminal breast cancer, as well as precise molecular tools for predicting prognosis.

Methods

We compared methylation levels of normal and luminal breast cancer samples from The Cancer Genome Atlas dataset. The relationships among differentially methylated sites, corresponding mRNA expression levels and prognosis were further analysed. Differentially expressed genes in normal and cancerous samples were analysed, followed by the identification of prognostic signature genes. Samples were divided into low- and high-risk groups based on the signature genes. Prognoses of low- and high-risk groups were compared. The Gene Expression Omnibus dataset were used to validate signature genes for prognosis prediction. Prognosis of low- and high-risk groups in Luminal A and Luminal B samples from the TCGA and the Metabric cohort dataset were analyzed. We also analysed the correlation between clinical features of low- and high- risk groups as well as their differences in gene expression.

Results

Fourteen methylation sites were considered to be related to luminal breast cancer prognosis because their methylation levels, mRNA expression and prognoses were closely related to each other. The methylation level of SOSTDC1 was used to divide samples into hypo- and hyper-methylation groups. We also identified an mRNA signature, comprising eight transcripts, ESCO2, PACSIN1, CDCA2, PIGR, PTN, RGMA, KLK4 and CENPA, which was used to divide samples into low- and high-risk groups. The low-risk group showed significantly better prognosis than the high-risk group. A correlation analysis revealed that the risk score was an independent prognostic factor. Low- and high- risk groups significantly correlated with the survival ratio in Luminal A samples, but not in Luminal B samples on the basis of the TCGA and the Metabric cohort dataset. Further functional annotation demonstrated that the differentially expressed genes were mainly involved in cell cycle and cancer progression.

Conclusions

We identified several key methylation sites and an mRNA signature for predicting luminal breast cancer prognosis. The signature exhibited effective and precise prediction of prognosis and may serve as a prognostic and diagnostic marker for luminal breast cancer.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4314-9) contains supplementary material, which is available to authorized users.

Discovery of novel transcripts of the human tissue kallikrein (KLK1) and kallikrein-related peptidase 2 (KLK2) in human cancer cells, exploiting Next-Generation Sequencing technology

Tissue kallikrein, kallikrein-related peptidases (KLKs), and plasma kallikrein form the largest group of serine proteases in the human genome, sharing many structural and functional properties. Several KLK transcripts have been found aberrantly expressed in numerous human malignancies, confirming their prognostic or/and diagnostic values. However, the process of alternative splicing can now be studied in-depth due to the development of Next-Generation Sequencing (NGS). In the present study, we used NGS to discover novel transcripts of the KLK1 and KLK2 genes, after nested touchdown PCR. Bioinformatics analysis and PCR experiments revealed a total of eleven novel KLK transcripts (two KLK1 and nine KLK2 transcripts). In addition, the expression profiles of each novel transcript were investigated with nested PCR experiments using variant-specific primers. Since KLKs are implicated in human malignancies, qualifying as potential biomarkers, the quantification of the presented novel transcripts in human samples may have clinical applications in different types of cancer.

Molecular cloning of novel transcripts of human kallikrein-related peptidases 5, 6, 7, 8 and 9 (KLK5 - KLK9), using Next-generation sequencing

Alternative splicing of cancer-related genes is a common cellular mechanism accounting for cancer cell transcriptome complexity and affecting cell cycle control, proliferation, apoptosis, angiogenesis, invasion, and metastasis. In this study, we describe the discovery and molecular cloning of thirty novel transcripts of the human KLK5, KLK6, KLK7, KLK8 and KLK9 genes, using 3′ rapid amplification of cDNA ends (3′ RACE) and NGS technology, as well as their expression analysis in many established cell lines, originating from several distinct cancerous and normal tissues. Extensive bioinformatic analysis revealed novel splice variants of these five members of the KLK family, comprising entirely new exons, previously unknown boundaries of the already annotated exons (extensions and truncations) as well as alternative splicing events between these exons. Nested RT-PCR in a panel of human cell lines originating from seventeen cancerous and two normal tissues with the use of variant-specific pairs of primers was carried out for expression analysis of these novel splice variants, and Sanger sequencing of the respective amplicons confirmed our NGS results. Given that some splice variants of KLK family members possess clinical value, novel alternatively spliced transcripts appear as new candidate biomarkers for diagnostic and/or prognostic purposes and as targets for therapeutic strategies.

Aberrant KLK4 gene promoter hypomethylation in pediatric hepatoblastomas

DNA methylation has a crucial role in cancer biology and has been recognized as an activator of oncogenes and inactivator of tumor suppressor genes, both of which are mechanisms for tumorigenesis. Kallikrein-related peptidase 4 (KLK4), has been suggested to be an oncogene in various types of cancer. The aim of the present study was to assess the DNA methylation patterns of the KLK4 gene in cancerous samples harvested from patients with hepatoblastoma (HB). KLK4 mRNA expression levels were detected using reverse transcription-quantitative polymerase chain reaction and assessed its DNA methylation patterns using high-throughput mass spectrometry on a matrix-assisted laser desorption/ionization time-of-flight mass array. A total of 10 HB and 10 normal liver tissue samples were obtained from patients with HB. The results of the present study showed that a significantly higher level of KLK4 mRNA expression levels were detected in HB tissues, as compared with the matched controls. Furthermore, the KLK4 gene promoter region was distinctively less methylated in the HB samples compared with the controls and negatively correlated with KLK4 mRNA expression levels. These findings indicate that aberrant methylation of KLK4 may contribute to its upregulated mRNA expression in HB.

Involvement of Kallikrein-Related Peptidases in Normal and Pathologic Processes

Human kallikrein-related peptidases (KLKs) are a subgroup of serine proteases that participate in proteolytic pathways and control protein levels in normal physiology as well as in several pathological conditions. Their complex network of stimulatory and inhibitory interactions may induce inflammatory and immune responses and contribute to the neoplastic phenotype through the regulation of several cellular processes, such as proliferation, survival, migration, and invasion. This family of proteases, which includes one of the most useful cancer biomarkers, kallikrein-related peptidase 3 or PSA, also has a protective effect against cancer promoting apoptosis or counteracting angiogenesis and cell proliferation. Therefore, they represent attractive therapeutic targets and may have important applications in clinical oncology. Despite being intensively studied, many gaps in our knowledge on several molecular aspects of KLK functions still exist. This review aims to summarize recent data on their involvement in different processes related to health and disease, in particular those directly or indirectly linked to the neoplastic process.

KLK11 mRNA expression predicts poor disease-free and overall survival in colorectal adenocarcinoma patients

BACKGROUND

Dysregulated expression of several KLK family members has been observed in colorectal adenocarcinoma. In the present study, the prognostic value of KLK11 mRNA expression as a molecular tissue biomarker in colorectal adenocarcinoma was examined.

MATERIALS & METHODS

Using quantitative real-time PCR, KLK11 mRNA expression was studied in 120 cancerous and 41 paired noncancerous colorectal specimens obtained from 120 patients with primary colorectal adenocarcinoma.

RESULTS

A significant upregulation of KLK11 transcripts in colorectal tumors was observed. KLK11 mRNA expression was associated with the depth of tumor invasion and the histological grade. Furthermore, KLK11 mRNA expression predicted poor disease-free and overall survival, independently of patient gender, age, tumor size, location, histological subtype, grade, venous invasion, lymphatic invasion, TNM stage, radiotherapy and chemotherapy treatment.

CONCLUSION

KLK11 mRNA expression could be considered as a new molecular prognostic biomarker in colorectal adenocarcinoma, with additional prognostic value in patients with highly invasive tumors and/or positive lymph nodes.

Kallikrein-related peptidase-6 (KLK6) mRNA expression is an independent prognostic tissue biomarker of poor disease-free and overall survival in colorectal adenocarcinoma

Members of the family of tissue kallikrein and kallikrein-related peptidases possess important prognostic value in cancer. Moreover, the oncogenic role of kallikrein-related peptidase-6 (KLK6) in colorectal cancer has been well documented so far. This study investigated the prognostic value of KLK6 mRNA expression as a molecular tissue biomarker in colorectal adenocarcinoma. For this purpose, KLK6 mRNA expression was studied in 110 primary colorectal adenocarcinomas and 39 paired noncancerous colorectal specimens. A dramatic upregulation of KLK6 mRNA expression was observed in colorectal tumors. KLK6 mRNA overexpression was associated with high depth of tumor invasion, presence of distant metastases, and tumor-node-metastasis (TNM) stage of patients. Furthermore, KLK6 mRNA expression was shown to predict poor disease-free and overall survival independently of patient gender, age, tumor size, location, histological subtype, grade, venous invasion, lymphatic invasion, TNM stage, radiotherapy, and chemotherapy treatment. Moreover, Kaplan-Meier survival analysis revealed that colorectal adenocarcinoma patients with negative regional lymph nodes (N0) and those without distant metastases (M0) harboring KLK6 mRNA-positive colorectal tumors tended to relapse and die earlier than N0 and M0 patients with KLK6 mRNA-negative colorectal adenocarcinoma. Thus, KLK6 mRNA expression could be considered as an independent, unfavorable molecular prognostic biomarker in colorectal adenocarcinoma, with additional prognostic value in patients without regional or distant metastases.

The role of kinin receptors in cancer and therapeutic opportunities

Kinins are generated within inflammatory tissue microenvironments, where they exert diverse functions, including cell proliferation, leukocyte activation, cell migration, endothelial cell activation and nociception. These pleiotropic functions depend on signaling through two cross talking receptors, the constitutively expressed kinin receptor 2 (B2R) and the inducible kinin receptor 1 (B1R). We have reviewed evidence, which supports the concept that kinin receptors, especially kinin receptor 1, are promising targets for cancer therapy, since (1) many tumor cells express aberrantly high levels of these receptors; (2) some cancers produce kinins and use them as autocrine factors to stimulate their growth; (3) activation of kinin receptors leads to activation of macrophages, dendritic cells and other cells from the tumor microenvironment; (4) kinins have pro-angiogenic properties; (5) kinin receptors have been implicated in cancer migration, invasion and metastasis; and (6) selective antagonists for either B1R or B2R have shown anti-proliferative, anti-inflammatory, anti-angiogenic and anti-migratory properties. The multiple cross talks between kinin receptors and renin-angiotensin system (RAS) as well as its implications for targeting KKS or RAS for the treatment of malignancies are also discussed. It is expected that B1R antagonists would interfere less with housekeeping functions and therefore would be attractive compounds to treat selected types of cancer. Reliable clinical studies are needed to establish the translatability of these data to human settings and the usefulness of kinin receptor antagonists.

The kinin-kallikrein system: physiological roles, pathophysiology and its relationship to cancer biomarkers

The kinin-kallikrein system (KKS) is an endogenous multiprotein cascade, the activation of which leads to triggering of the intrinsic coagulation pathway and enzymatic hydrolysis of kininogens with the consequent release of bradykinin-related peptides. This system plays a crucial role in inflammation, vasodilation, smooth muscle contraction, cardioprotection, vascular permeability, blood pressure control, coagulation and pain. In this review, we will outline the physiology and pathophysiology of the KKS and also highlight the association of this system with carcinogenesis and cancer progression.

Clinical significance of kallikrein-related peptidase (KLK10) mRNA expression in colorectal cancer

OBJECTIVES

Colorectal cancer (CRC) is one of the three most common cancers in both genders. Even though several biomarkers are in use in diagnosis and prognosis of the disease, they are marred by limited specificity and sensitivity. The human kallikrein-related peptidase 10 (KLK10) gene is a member of the human tissue kallikrein family. Because prostate specific antigen (PSA), the best biomarker for detecting and monitoring prostate cancer, is a member of this family, many other members, including KLK10, have been widely examined as novel biomarkers for different cancer types. In previous studies, KLK10 has been proposed as a diagnostic biomarker for ovarian carcinoma, while its methylation on exon 3 has been proposed as a prognostic marker for early-stage breast cancer patients. The purpose of this study was to analyse KLK10 mRNA expression and examine its prognostic value and potential clinical application as a novel molecular tissue biomarker in CRC.

DESIGN AND METHODS

The study group consisted of 190 colorectal samples. Total RNA was extracted from pulverised tissues and cDNA was prepared by reverse transcription. KLK10 was amplified by real-time PCR. B2M was used as a reference gene and HT-29 cells as positive control.

RESULTS

KLK10 expression was significantly higher in cancer tissues (P<0.001). Tumours of advanced TNM and Dukes' stage showed high KLK10 expression status (P=0.036; P=0.025). Patients with high KLK10 expression had a shorter disease-free and overall survival rates (P=0.014; P=0.020).

CONCLUSION

Our results suggest that KLK10 may serve as a new marker of unfavourable prognosis of colorectal cancer.

Kallikrein-related peptidases (KLKs) in gastrointestinal cancer: mechanistic and clinical aspects

The human tissue kallikrein (KLK1) and kallikrein-related peptidases (KLKs) are secreted serine proteases with diverse expression patterns and physiological roles in different systems, including the digestive system. The aberrant expression of KLKs in gastrointestinal malignancies as well as their implication in carcinogenesis including cell growth regulation, angiogenesis, invasion, and metastasis, has prompted scientists to investigate their potential as cancer biomarkers. Expression of distinct KLKs is associated with various clinic-pathological parameters of patients with gastric, colorectal, pancreatic, hepatic, and esophageal cancer. Moreover, several KLKs possess significant favourable or unfavourable prognostic value in these human malignancies. Identification of novel diagnostic, prognostic and predictive biomarkers will contribute utmost to clinical decision-making, since early diagnosis of gastrointestinal cancer and early detection of recurrence following surgery are critical for the effective treatment of patients and for a positive clinical outcome. The current review provides a brief overview of the functional role of KLKs in gastric, colorectal, pancreatic, hepatic, and esophageal cancer, and describes the current status of KLKs as potential tumour biomarkers in these human malignancies.