Kallikrein-related peptidase 13 (KLK13) gene expressional status contributes significantly in the prognosis of primary gastric carcinomas

Triterpenoid ursolic acid regulates the environmental carcinogen benzo[a]pyrene-driven epigenetic and metabolic alterations in SKH-1 hairless mice for skin cancer interception

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental carcinogens accountable to developing skin cancers. Recently, we reported that exposure to benzo[a]pyrene (B[a]P), a common PAH, causes epigenetic and metabolic alterations in the initiation, promotion and progression of non-melanoma skin cancer (NMSC). As a follow-up investigation, this study examines how dietary triterpenoid ursolic acid (UA) regulates B[a]P-driven epigenetic and metabolic pathways in SKH-1 hairless mice. Our results show UA intercepts against B[a]P-induced tumorigenesis at different stages of NMSC. Epigenomic cytosines followed by guanine residues (CpG) methyl-seq data showed UA diminished B[a]P-mediated differentially methylated regions (DMRs) profiles. Transcriptomic RNA-seq revealed UA revoked B[a]P-induced differentially expressed genes (DEGs) of skin cancer-related genes, such as leucine-rich repeat LGI family member 2 (Lgi2) and kallikrein-related peptidase 13 (Klk13), indicating UA plays a vital role in B[a]P-mediated gene regulation and its potential consequences in NMSC interception. Association analysis of DEGs and DMRs found that the mRNA expression of KLK13 gene was correlated with the promoter CpG methylation status in the early-stage comparison group, indicating UA could regulate the KLK13 by modulating its promoter methylation at an early stage of NMSC. The metabolomic study showed UA alters B[a]P-regulated cancer-associated metabolisms like thiamin metabolism, ascorbate and aldarate metabolism during the initiation phase; pyruvate, citrate and thiamin metabolism during the promotion phase; and beta-alanine and pathothenate coenzyme A (CoA) biosynthesis during the late progression phase. Taken together, UA reverses B[a]P-driven epigenetic, transcriptomic and metabolic reprogramming, potentially contributing to the overall cancer interception against B[a]P-mediated NMSC.

Prospective quantitative gene expression analysis of kallikrein-related peptidase KLK10 as a diagnostic biomarker for childhood acute lymphoblastic leukemia

Background

The most common malignancy in children is acute lymphoblastic leukemia (ALL). This study aimed to explore KLK10 mRNA expression as a potential diagnostic biomarker for ALL in children and to examine the effect of chemotherapy on KLK10 mRNA expression following the induction and after three months of receiving chemotherapy.

Methods

In this prospective study, total RNA was extracted from blood samples of 23 pediatric ALL patients on diagnosis, after one month and three months of receiving chemotherapy. Healthy pediatric volunteers (n = 12) were selected as control individuals. After cDNA synthesis, KLK10 mRNA gene expression levels were quantified using quantitative real-time PCR (qRT-PCR).

Results

KLK10 mRNA expression levels were significantly decreased in leukemic cells compared to their levels in cells of normal blood samples (p = 0.0001). KLK10 expression levels in ALL patients after one month and three months of receiving chemotherapy decreased compared to normal blood samples (p < 0.0001 and p = 0.0175 respectively). The expression level of KLK10 mRNA in ALL patients after one month of chemotherapy was decreased compared to their level on diagnosis (p = 0.4413). KLK10 mRNA expression levels in ALL patients after three months of chemotherapy were increased compared to their level on diagnosis (p = 0.0602). The ROC curve illustrated that KLK10 mRNA expression could very efficiently discriminate ALL patients from normal counterparts (AUC=0.886, 95% CI [0.7720-1.000], SE = 0.0582, p = 0.0004).

Conclusion

KLK10 mRNA expression could serve as a potential diagnostic molecular biomarker for ALL in children.

Analysis of urinary kallikrein-related peptidase 13 for monitoring bladder cancer

BACKGROUND

Bladder cancer (BC) is one of the 10 most common types of cancer worldwide, with approximately 550,000 new cases each year. Early detection and appropriate diagnosis are important factors in successful treatment of the disease.

MATERIAL AND METHODS

We used specific fluorogenic substrate for the quantitative determination of urine kallikrein 13 (KLK13) activity in healthy (n = 15) and BC (n = 54) patients. The proteolytic activity in individual urine samples was determined by fluorescence measurements. Then, immunoenzymatic analyses (ELISA, Western blot) were performed to confirm the presence of KLK13 in the tested samples.

RESULTS

Urine samples from patients with G2 and G3 grade BC contained proteolytically active KLK13, as confirmed by kinetic analysis and immunochemical detection. KLK13 was not detected in the urine of patients with G1 grade BC.

DISCUSSION

Previous clinical study reveals the KLK13 significance for BC prognosis as increased KLK13 expression was highlighted in bladder tumours compared to normal adjacent tissues. Our findings correlate to the report. KLK13 activity was confirmed in BC patients with G2 and G3 stage of disease development.

CONCLUSIONS

Using specific chromogenic/fluorogenic peptides could be useful for the non-invasive disease monitoring of BC progress.

Cancer-related proteins in serum are altered in workers occupationally exposed to polycyclic aromatic hydrocarbons: a cross-sectional study

Exposure to some polycyclic aromatic hydrocarbons (PAH) increases the risk of cancer and is common particularly for workers in occupations such as chimney sweeping. In exposed workers, screening of early cancer-related markers provides important information to identify individuals at risk. Here, we aimed to elucidate the associations between PAH exposure and serum levels of cancer-related proteins in 118 chimney sweeps and 126 occupationally unexposed controls, all non-smoking males from Sweden. Monoydroxylated metabolites of pyrene, phenanthrene, benzo[a]pyrene and benzo[a]anthracene were measured in urine using liquid chromatography coupled to tandem mass spectrometry and 90 cancer-related proteins were measured in serum using a proximity extension assay. Linear regression analysis adjusted for age and body mass index, and false discovery rate (FDR) identified 17 serum proteins that were differentially expressed (16 upregulated and 1 downregulated) in chimney sweeps compared with controls (FDR < 0.05). Concentrations of the peptidase kallikrein 13 (KLK13) showed significant positive associations with urinary concentrations of the PAH metabolites 3-hydroxybenzo[a]pyrene (3-OH-BaP) [B, 95% confidence interval (CI): 0.042, 0.008–0.076] and 3-hydroxybenzo[a]anthracene (3-OH-BaA) (B, 95% CI: 0.068, 0.002–0.134). Moreover, dose–response relationships were observed between KLK13 and 3-OH-BaP (trend test P = 0.027) and 3-OH-BaA (P = 0.035). Pathway and gene ontology analyses showed that cell movement, cell adhesion and cell migration were the predominant molecular functions associated with the top differentially expressed proteins. In conclusion, we found a number of putative cancer-related proteins differentially expressed in workers exposed to PAH. This warrants effective measure to reduce PAH exposure among workers as well as further investigation to confirm these findings.

Searching for serum protein markers of equine squamous gastric disease using gel electrophoresis and mass spectrometry

BACKGROUND

Equine squamous gastric disease (ESGD) is a very common disorder but an accurate and practical screening technique for detecting ESGD is currently lacking.

OBJECTIVES

To identify serum protein markers to detect ESGD using electrophoresis and mass spectrometry.

STUDY DESIGN

Proteomic analysis and bioinformatics.

METHODS

ESGD was diagnosed using gastroscopy in 30 horses. Gastric ulceration was categorised into three groups: normal, mild/moderate and severe ESGD. Pooled sera from each group were compared using 1D electrophoresis and mass spectrometry. The candidate proteins for ESGD markers were selected based on their specifically high expression in nonglandular stomach, and their association with gastric ulceration using public gene and protein databases.

RESULTS

The prevalence of ESGD in this study was 43% (with mild/moderate ESGD at 33% and severe ESGD at 10%). The proteomic study revealed that the identified serum protein markers for normal equine stomach were B4GALNT2 and XDH. The marker for mild/moderate EGSD was KRT10, while the marker for severe ESGD was KLK13. Furthermore, markers for both ulcer types were SLC4A7, PPARG, FCGBP, PKP1, ASPRV1 and KRT5-like proteins.

MAIN LIMITATIONS

The functions of the identified proteins are not well characterised in horse. Proteomics is a tool for screening protein markers, but confirmation of putative protein markers with specific antibodies is required.

CONCLUSIONS

In total, 10 serum proteins found in this study may be used as putative markers for ESGD. However, confirmation of candidate proteins with specific antibodies in a larger study cohort is necessary before it can be used in the veterinary clinic or on horse farms. The Summary is available in Portuguese - see Supporting Information.

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.

Advanced high-grade serous ovarian cancer: inverse association of KLK13 and KLK14 mRNA levels in tumor tissue and patients' prognosis

PURPOSE

Gene expression of a variety of the 15 members of the KLK serine protease family is dysregulated in ovarian cancer. We aimed at determining the clinical relevance of KLK13 and KLK14 mRNA expression in tumor tissues of a homogeneous patient cohort afflicted with advanced high-grade serous ovarian cancer (FIGO stage III/IV).

METHODS

mRNA expression levels of KLK13 and KLK14 were assessed by quantitative PCR in tumor tissue of 91 patients and related with clinical factors and patients' outcome.

RESULTS

There was no significant association of KLK13 and KLK14 mRNA expression with the clinical factors ascitic fluid volume or residual tumor mass. In univariate Cox regression analysis, elevated KLK13 mRNA levels were significantly linked with shorter progression-free (PFS; hazard ratio [HR] = 1.97, P = 0.020) and overall survival (OS; HR = 1.81, P = 0.041). High KLK14 mRNA levels were significantly associated with prolonged PFS (HR = 0.44, P = 0.017) and showed a trend towards significance for OS (HR = 0.55, P = 0.070). In multivariable analysis, including the factors age, residual tumor mass, ascitic fluid volume, KLK13, and KLK14, both KLKs, apart from residual tumor mass, remained statistically independent predictive markers: patients with high KLK13 mRNA expression levels displayed a more than twofold increase risk for shorter PFS (HR = 2.14, P = 0.020) as well as OS (HR = 2.05, P = 0.028), whereas elevated KLK14 mRNA values were found to be significant for both, prolonged PFS (HR = 0.36, P = 0.007) and OS (HR = 0.46, P = 0.037).

CONCLUSION

These results indicate that in advanced high-grade serous ovarian cancer KLK13 may become proficient for tumor-supporting functions, whereas KLK14 may have adopted tumor-suppressing activity.

Downregulation of KLK13 promotes the invasiveness and metastasis of oesophageal squamous cell carcinoma

KLK13 downregulation occurs in tumour tissues in comparison with adjacent normal tissues from patients with oesophageal squamous cell carcinoma (OSCC). KLK13 mRNA levels were tested in OSCC tumour tissues and adjacent noncancerous tissues from 138 patients. In addition, the correlation between KLK13 mRNA levels and OSCC clinicopathologic features was analysed. KLK13 mRNA levels decreased notably in tumour tissues compared with those in adjacent noncancerous tissues. And decreased KLK13 mRNA levels indicated significant correlations with higher tumour grade, elevated TNM (UICC, 2009) stage classification, deeper infiltration and more lymph node metastases. And thus KLK13 may be a promising diagnostic marker. Decreased KLK13 mRNA levels also correlate with poor survival, which indicates that KLK13 mRNA expression may be a potential prognostic marker, although it could not be an independent prognostic factor by multivariate analysis. In vitro experiments of the OSCC cell lines KYSE150 and KYSE450 demonstrated that overexpression of KLK13 inhibits cell invasion and migration. Thus, KLK13 is a unique novel molecule useful for monitoring OSCC progression. Full elucidation of the role of KLK13 in OSCC may reveal avenues for investigating the molecule's functional potential as a novel therapeutic drug for targeting OSCC.

Plasmin(ogen) serves as a favorable biomarker for prediction of survival in advanced high-grade serous ovarian cancer

In serous ovarian cancer, the clinical relevance of tumor cell-expressed plasmin(ogen) (PLG) has not yet been evaluated. Due to its proteolytic activity, plasmin supports tumorigenesis, however, angiostatin(-like) fragments, derived from PLG, can also function as potent anti-tumorigenic factors. In the present study, we assessed PLG protein expression in 103 cases of advanced high-grade serous ovarian cancer (FIGO III/IV) by immunohistochemistry (IHC). In 70/103 cases, positive staining of tumor cells was observed. In univariate Cox regression analysis, PLG staining was positively associated with prolonged overall survival (OS) [hazard ratio (HR)=0.59, p=0.026] of the patients. In multivariable analysis, PLG, together with residual tumor mass, remained a statistically significant independent prognostic marker (HR=0.49, p=0.009). In another small patient cohort (n=29), we assessed mRNA expression levels of PLG by quantitative PCR. Here, elevated PLG mRNA levels were also significantly associated with prolonged OS of patients (Kaplan-Meier analysis; p=0.001). This finding was validated by in silico analysis of a microarray data set (n=398) from The Cancer Genome Atlas (Kaplan-Meier analysis; p=0.031). In summary, these data indicate that elevated PLG expression represents a favorable prognostic biomarker in advanced (FIGO III/IV) high-grade serous ovarian cancer.

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.

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.

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.

Prognostic significance of human tissue kallikrein-related peptidases 11 and 15 in gastric cancer

Human tissue kallikrein-related peptidases (KLK) are a group of 15 serine proteases which have been investigated as potential cancer biomarkers. This study determined the prognostic significance of KLK 11 and 15 expression levels in gastric carcinoma specimens. Expression of KLK11 and KLK15 was assessed by immunohistochemistry staining on a tissue microarray constructed from 113 gastrectomy specimens from patients with gastric carcinoma. To minimize inter-observer variability, expression levels were quantified using an automated algorithm. Epithelial and stromal staining were assessed separately. Both KLK11 and KLK15 were expressed in gastric carcinoma. There was no significant correlation between either KLK11 or KLK15 expression and the presence of lymph node metastases or Lauren classification (intestinal vs. diffuse). Higher levels of KLK11 expression in gastric carcinoma were associated with significantly worse overall survival (p = 0.008), and a multivariate analysis showed that it had prognostic value independent of tumor stage and differentiation (p = 0.004). Variations in KLK15 expression were not significantly associated with prognosis. KLK11 shows promise as a potential independent prognostic marker for gastric carcinoma.

Kallikrein-related peptidase 13: an independent indicator of favorable prognosis for patients with nonsmall cell lung cancer

The KLK13 gene is dysregulated in several carcinomas, and its expression levels seem to be associated with disease prognosis. The aim of our study was to investigate the prognostic potential of KLK13 mRNA expression for patients with nonsmall cell lung cancer (NSCLC). Total RNA was isolated from cancerous and normal tissues from a cohort of 128 NSCLC patients. The KLK13 mRNA transcription levels were measured using a sensitive quantitative RT-PCR method. The results were normalized by dividing the KLK13 mRNA values with the geometric mean of mRNA expression from four reference genes: beta-actin, TATA-binding protein, hypoxanthine phosphoribosyltransferase 1, and acidic ribosomal phosphoprotein P0. The malignant tissues from the majority of patients (59.3 %) contained significantly more KLK13 mRNA transcripts than did the paired nonmalignant tissues (median difference 11.1-fold, P = 0.008). KLK13 was expressed at higher levels in females than that in males (P = 0.021). No other statistically significant association with clinicopathological data was observed. Kaplan-Meier survival analyses demonstrated that patients with KLK13-positive tumors survived significantly longer than those with KLK13-negative ones (P = 0.009). KLK13 expression was also shown to be able to stratify high-risk individuals among patients with early disease stages (P = 0.030). Multivariate Cox regression analysis showed that KLK13 expression is a favorable, independent prognostic indicator of overall survival (OS) (P = 0.024). Our results suggest that KLK13 mRNA expression constitutes a novel biomarker for the prediction of overall survival in NSCLC and that its quantitative assessment in tumor tissues can aid in treatment decision making.

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.

Decreased expression of kallikrein-related peptidase 13: possible contribution to metastasis of human oral cancer

The human kallikrein-related peptidase family is comprised of 15 serine protease genes on chromosome 19q13.4. Our previous microarray analyses showed that the gene kallikrein-related peptidase 13 (KLK13) was down-regulated in oral squamous cell carcinoma (OSCC) cell lines. We evaluated the expression status of KLK13 in primary OSCCs and performed functional molecular experiments in OSCC cell lines. In 102 primary tumors studied, KLK13 expression significantly (P < 0.05) decreased compared with matched normal counterparts. Interestingly, KLK13-negative cases correlated significantly (P < 0.05) with regional lymph node metastasis. In vitro, cells overexpressing KLK13 (oeKLK13) had decreased invasiveness and motility and up-regulation of adhesion molecules (E-cadherin, α-catenin, β-catenin, junction plakoglobin, plakophilin4, desmocollin2, desmoglein3, and desmoplakin) compared with control cells. A rescue experiment that transfected oeKLK13 cells with siRNA against KLK13 restored invasiveness and migration activities with down-regulated adhesion molecules. Based on our results, we concluded that KLK13 may play an important role in regulating cellular migration and invasiveness, making the loss of KLK13 a potential biomarker for early detection of lymph node metastasis in OSCCs.

Clinical significance of human kallikrein 12 gene expression in gastric cancer

AIM: To investigate whether the expression of kallikrein 12 (KLK12) is related to the development of gastric cancer (GC) and to determine the role of KLK12 in gastric cancer cells growth, invasion and migration.

METHODS: Between September 2007 and March 2008, 133 patients with histologically confirmed GC were recruited for the study. Expression of KLK12 was detected in samples from GC patients by quantitative real-time reverse transcription polymerase chain reaction and immunohistochemistry. The relationship between KLK12 protein expression and clinicopathological features of GC was analyzed. The difference in 5-year survival rates between the high KLK12 protein expression group and the low KLK12 expression group was compared. Additionally, the expression of KLK12 was examined in various human GC cell lines, including MKN-28, SGC-7901 and MKN-45. Small interfering RNA (siRNA) was used to inhibit KLK12 expression in MKN-45 cells. Cell clones stably transfected with KLK12 siRNA were tested for KLK12 expression by quantitative real-time reverse transcription-polymerase chain reaction and Western blotting. Furthermore, a series of functional assays were performed in this study to assess the biological features of transfected cells. Cell proliferation was assessed using the methylthiazolyltetrazoliumassay. Finally, cell migration and invasion were assessed using transwell chamber assays.

RESULTS: Of the 133 GC patients included in the study, 126 (94.7%) showed a higher expression level of KLK12 mRNA when compared to noncancerous tissue specimens. Expression of KLK12 mRNA was significantly higher in GC tissues than in normal tissue (P < 0.001). KLK12 protein expression was detected in 96 of 133 (72.2%) GC samples with moderate or strong staining primarily in the cytoplasm. In contrast, negative immunostaining for KLK12 protein was observed in the corresponding normal gastric mucosal tissue. Overexpression of KLK12 protein was significantly associated with lymph node metastasis (P = 0.001), histological type (P < 0.001) and tumor-node-metastasis stage (P = 0.005), while no significant correlation was observed between expression of KLK12 protein and sex, age, depth of invasion, tumor size or lymphatic invasion. Furthermore, patients with high KLK12 expression had a significantly poorer 5-year survival rate than those with low KLK12 expression (P = 0.002). Expression of KLK12 mRNA was significantly higher in MKN-45 GC cells compared to normal mucosal cells or two other GC cell lines (P < 0.01). Expression of KLK12 in MKN-45 cells was downregulated after transfection with siRNA. Knockdown of KLK12 markedly decreased the proliferation of MKN-45 cells when compared with parent or mock-transfected cells (P = 0.001), especially from the 3rd to the 5th day of the assay. In migration assays, fewer KLK12 siRNA cells migrated through the chambers (22.00 ± 1.81) when compared to the parent (46.47 ± 2.42) or mock-transfected cells (45.40 ± 1.99); these differences were statistically significant (P < 0.001). However, in the invasion assay, the number of KLK12 siRNA cells that invaded the chambers was 18.40 ± 1.12, closely similar to both the parent (18.67 ± 0.98) and mock-transfected cells (18.53 ± 0.92). There was no significantly difference between the three groups in the invasion assay (P = 0.054).

CONCLUSION: The KLK12 gene is markedly overexpressed in GC tissue, and its expression status may be a powerful prognostic indicator for patients with GC. KLK12 might serve as a novel diagnosis and prognosis biomarker in GC.

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

The members of the kallikrein-related peptidase (KLK) family are aberrantly expressed in cancer, including colorectal adenocarcinoma. KLK4 is an endogenous activator of protease-activated receptor 1 (PAR1) in HT-29 colorectal adenocarcinoma cells, inducing PAR1 signaling and subsequent ERK1/2 activation. The aim of this study was to analyze KLK4 mRNA expression in colorectal adenocarcinoma and to examine its prognostic value as a novel molecular tissue biomarker in this malignancy. Therefore, total RNA was isolated from primary tumors of 81 colorectal adenocarcinoma patients, cDNA was prepared, and KLK4 mRNA expression analysis was performed using quantitative real-time PCR. KLK4 mRNA was significantly associated with the Dukes stage, tumor invasion, size, and histological grade. Survival analysis demonstrated that KLK4 mRNA expression constitutes an unfavorable prognostic biomarker in colorectal adenocarcinoma, predicting poor disease-free survival (DFS), independently of the nodal status and tumor size. Furthermore, KLK4 mRNA predicts short-term relapse of lymph node-negative patients or those with tumors of early Dukes stage. In conclusion, KLK4 mRNA expression can be regarded as a novel potential tissue biomarker in colorectal adenocarcinoma.