Identification and validation of Kallikrein-ralated peptidase 11 as a novel prognostic marker of gastric cancer based on immunohistochemistry

KLK11 acts as a tumor-inhibitor in laryngeal squamous cell carcinoma through the inactivation of Akt/Wnt/β-catenin signaling

Kallikrein-associated peptidase 11 (KLK11) has emerged as a key tumor-associated protein that is implicated in a wide spectrum of tumor types. However, the detailed involvement of KLK11 in laryngeal squamous cell carcinoma (LSCC) has not been well studied. The aims of our work were to evaluate whether KLK11 plays a role in LSCC. We found that both the mRNA and protein expression of KLK11 were significantly lower in LSCC tissues than in normal tissues. Low expression of KLK11 was also observed in LSCC cell lines, and the up-regulation of KLK11 caused a significant inhibitory effect on the proliferation, colony formation and invasion of LSCC cells. On the contrary, the knockdown of KLK11 markedly accelerated the proliferative and invasive abilities of LSCC cells. Molecular mechanism research revealed that KLK11 overexpression decreased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and down-regulated the expression of active β-catenin, leading to the inactivation of Wnt/β-catenin signaling in LSCC cells. Furthermore, GSK-3β inhibition markedly abrogated the KLK11-mediated suppressive effect on Wnt/β-catenin signaling. Notably, the reactivation of Wnt/β-catenin partially reversed KLK11-mediated tumor-inhibition effect in LSCC. In addition, the xenograft tumor assay demonstrated that the up-regulation of KLK11 retarded tumor formation and the growth of LSCC cells in vivo. Taken together, the findings of our work demonstrate that KLK11 exerts a tumor-inhibition role in LSCC by down-regulating Wnt/β-catenin signaling. Our work highlights a pivotal role of KLK11 in LSCC progression and suggests it as an attractive anticancer target for LSCC treatment.

Novel splice variants of the human kallikrein-related peptidases 11 (KLK11) and 12 (KLK12), unraveled by 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 characteristics. In this study, we describe the molecular cloning of four novel splice variants of the human KLK11 and KLK12 genes, discovered by combining 3' rapid amplification of cDNA ends (3' RACE), next-generation sequencing (NGS) technology, advanced bioinformatic analysis and Sanger sequencing. Expression analysis of these new transcripts in cell lines originating from 17 cancerous and two normal tissues revealed the expression pattern of each transcript. These novel KLK11 and KLK12 splice variants represent new potential cancer biomarkers.

Alterations in gene expression and DNA methylation profiles in gastric cancer cells obtained from ascitic fluids collected before and after chemotherapy

Resistance to anticancer drugs is a critical issue in cancer treatment. Alterations in gene expression and DNA methylation profiles that accompany the acquisition of drug resistance are associated with resistance mechanisms. To analyze chemotherapy-associated alterations in gene expression and DNA methylation in gastric cancer cells obtained from ascites, ascitic fluids were collected from a patient with gastric cancer before chemotherapy with capecitabine and oxaliplatin (CapeOX), and after the disease had progressed. The fluids were cultured for 10 days, passaged into new flasks, and cultured for an additional 2 weeks. Normal cells, including white blood cells and mesothelial cells, were removed. The expression and DNA methylation profiles of 18,185 genes were analyzed using microarray, and compared between cells in ascitic fluids collected before and after the chemotherapy with CapeOX. In addition, fluorouracil- and oxaliplatin-resistant AGS cells were established and analyzed. Pathways having genes with expression profiles altered by CapeOX included those associated with 'signaling by G-protein-coupled receptor' and the 'immune system'. Genes that were commonly expressed at higher levels in CapeOX-resistant ascitic cells, fluorouracil-resistant AGS cells. and oxaliplatin-resistant AGS cells compared with those in untreated cells included telomerase reverse transcriptase (TERT), apolipoprotein C1 (APOC1) and serine/threonine/tyrosine kinase 1 (STYK1), whereas genes commonly expressed at lower levels in the three drug-resistant cell types compared with the untreated cells included defensin β4A (DEFB4A). A comparatively large number of genes exhibited altered methylation levels in drug-resistant AGS cells compared with the CapeOX-resistant cells. In addition, among the genes expressed at higher levels in decitabine-treated AGS cells, the majority were expressed at higher levels in fluorouracil-resistant AGS cells, and exhibited lower methylation levels. Taken together, the present study has demonstrated that comparing the expression profiles of gastric cancer cells obtained from ascitic fluids before and after chemotherapy with the expression profiles of drug-resistant cultured cells is a useful method for analyzing the molecular mechanisms underlying chemotherapy resistance.

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.

Knockdown of KLK11 reverses oxaliplatin resistance by inhibiting proliferation and activating apoptosis via suppressing the PI3K/AKT signal pathway in colorectal cancer cell

Introduction

Kallikrein 11 (KLK11) plays a crucial role in drug-resistance to oxaliplatin (L-OHP) in the treatment of metastatic colorectal cancer (mCRC). The study aimed to investigate the role of KLK11 in chemoresistance, and to clarify the mechanism underlying reverse of L-OHP resistance by knockdown of KLK11.

Materials and Methods

Resistance to oxaliplatin was induced in HCT-8 (HCT-8/L-OHP) colorectal adenocarcinoma cell lines by exposing cells to increasing concentrations of L-OHP. MTT, RT-qPCR, and Western blot were used to evaluate the resistance to L-OHP. We then knocked down KLK11 in HCT-8/L-OHP cells to explore the mechanism through which KLK11 reverses L-OHP resistance. The mRNA and protein expression of KLK11 in tissues from mCRC patients were detected by RT-qPCR and immunohistochemistry.

Results

The drug resistance index (RI) of HCT-8/L-OHP cell line to L-OHP, 5-Fluorouracil (5-FU), Irinotecan (CPT-11), Vincristine (VCR) and Cis-diamminedichloroplatinum (CDDP) were 10, 5.35, 3.23, 1.28, and 6.64, respectively. Increased expression of multi-drug resistant genes ABCC1, ABCB1, GSTP1 and ERCC1 were detected in HCT-8/L-OHP cell line. Moreover, the activated PI3K/AKT pathway was related to L-OHP-resistance. Knockdown of KLK11 in HCT-8/L-OHP cell reversed L-OHP-resistance by inhibiting cell growth and activating apoptosis via suppressing the PI3K/AKT signaling pathway. Moreover, high expression of KLK11 in chemoresistant-patients was associated with lymph node metastases and histopathology.

Conclusion

KLK11 was highly expressed in chemoresistant-patients and L-OHP-resistant cell lines. Moreover, L-OHP resistance was associated with activated PI3K/AKT signal pathway. Knockdown of KLK11 can reverse L-OHP resistance by blocking PI3K/AKT signaling pathway.

Clinical relevance of kallikrein-related peptidase 9, 10, 11, and 15 mRNA expression in advanced high-grade serous ovarian cancer

KLK9, 10, 11, and 15 may represent potential cancer biomarkers for evaluating ovarian cancer prognosis. In the present study, we selected a homogeneous cohort including 139 patients of advanced high-grade serous ovarian cancer (FIGO stage III/IV) and assessed the mRNA levels of KLK9, 10, 11, and 15 in tumor tissue by quantitative PCR. No significant associations of KLK9, 10, 11, and 15 mRNA with established clinical parameters (residual tumor mass, ascitic fluid volume) were found. Pronounced correlations between KLK10/KLK11 (rs = 0.647) and between KLK9/KLK15 (rs = 0.716) mRNA, but not between other combinations, indicate coordinate expression of distinct pairs of peptidases. In univariate Cox regression analysis, elevated KLK11 mRNA levels were significantly linked with prolonged overall survival (OS; p = 0.021) and progression-free survival (PFS; p = 0.008). KLK15 mRNA levels showed a trend towards significance in case of OS (p = 0.06); KLK9 and KLK10 mRNA expression levels were not associated with patients' outcome. In multivariable Cox analysis, KLK11 mRNA expression levels, apart from residual tumor mass, remained an independent predictive marker for OS (p = 0.007) and PFS (p = 0.015). Here, elevated KLK15 mRNA expression levels turned out to be significantly related to prolonged OS (p = 0.025) as well. High KLK11 but not the other KLK mRNA levels can be considered as strong independent favorable prognostic factor in this major ovarian cancer subtype.

Elevated expression of CST1 promotes breast cancer progression and predicts a poor prognosis

Cystatin SN (CST1) belongs to the type 2 cystatin (CST) superfamily, which restricts the proteolytic activities of cysteine proteases. CST1 has been recently considered to be involved in the development of several human cancers. However, the prognostic significance and function of CST1 in breast cancer remains unknown. In the current study, we found that CST1 was generally upregulated in breast cancer at both mRNA and protein level. Furthermore, overall survival (OS) and disease-free survival (DFS) in the low CST1 expression subgroup were significantly superior to the high CST1 expression subgroup (OS, p < 0.001; DFS, p < 0.001), which indicated that CST1 expression level was closely correlated to the survival risk of these patients. Univariate and multivariate analyses demonstrated that CST1 expression was an independent prognostic factor, the same as ER status and nodal status. Next, CST1 overexpression promoted breast cancer cell proliferation, clonogenicity, migration, and invasion abilities. By contrast, knockdown of CST1 attenuated these malignant characteristics in breast cancer cells. Collectively, our study indicates that CST1 cannot only serve as a significant prognostic indicator but also as a potential therapeutic target for breast cancer.

KEY MESSAGES

High CST1 expression is negatively correlated with survival of breast cancer patients. CST1 promotes cell proliferation, clone formation, and metastasis in breast cancer cells. CST1 is a novel potential prognostic biomarker and therapeutic target for breast cancer.

Knockdown of KLK11 inhibits cell proliferation and increases oxaliplatin sensitivity in human colorectal cancer

It has been reported that kallikrein 11 (KLK11) is crucially involved in the development and progression of various types of cancer. However, the molecular mechanisms that underlie the involvement of KLK11 in aberrant colorectal cancer (CRC) cell growth remain largely unclear. The aim of the present study was to investigate the role of KLK11 and the effects of KLK11 on oxaliplatin (L-OHP) chemosensitivity by knocking down KLK11 in LOVO and HCT-8 cells. Loss-of-function assays revealed KLK11 inhibition significantly inhibited growth and induced apoptosis of CRC cells in vitro. Notably, further experiments found that knockdown of KLK11 expression increased the L-OHP chemosensitivity of CRC cells. KLK11 inhibition of increased L-OHP-induced apoptosis may be associated with activation of caspase-3 cleavage and the apoptosis signaling pathway. The present results indicated that KLK11 may be an potential target of interest for future research into therapies for CRC.

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.

SILAC-based quantitative proteomic analysis of gastric cancer secretome

PURPOSE

Gastric cancer is a commonly occurring cancer in Asia and one of the leading causes of cancer deaths. However, there is no reliable blood-based screening test for this cancer. Identifying proteins secreted from tumor cells could lead to the discovery of clinically useful biomarkers for early detection of gastric cancer.

EXPERIMENTAL DESIGN

A SILAC-based quantitative proteomic approach was employed to identify secreted proteins that were differentially expressed between neoplastic and non-neoplastic gastric epithelial cells. Proteins from the secretome were subjected to SDS-PAGE and SCX-based fractionation, followed by mass spectrometric analysis on an LTQ-Orbitrap Velos mass spectrometer. Immunohistochemical labeling was employed to validate a subset of candidates using tissue microarrays.

RESULTS

We identified 2205 proteins in the gastric cancer secretome of which 263 proteins were overexpressed greater than fourfold in gastric cancer-derived cell lines as compared to non-neoplastic gastric epithelial cells. Three candidate proteins, proprotein convertase subtilisin/kexin type 9 (PCSK9), lectin mannose binding 2 (LMAN2), and PDGFA-associated protein 1 (PDAP1) were validated by immunohistochemical labeling.

CONCLUSIONS AND CLINICAL RELEVANCE

We report here the largest cancer secretome described to date. The novel biomarkers identified in the current study are excellent candidates for further testing as early detection biomarkers for gastric adenocarcinoma.

Identification and validation that up-expression of HOXA13 is a novel independent prognostic marker of a worse outcome in gastric cancer based on immunohistochemistry

Homeobox (HOX) gene family is known to be classic examples of the intimate relationship between embryogenesis and tumorigenesis. However, less is known about the involvement of HOX gene family with gastric cancerogenesis. Here, we screened the expression of HOX gene family in gastric cancers and explored the relationships between them by cDNA microarray. We found several differentially expressed HOX genes in gastric cancers, especially HOXA10 (11/12) and HOXA13 (11/12) with significantly higher expression in the cancerous tissues. Furthermore, we validated HOXA13 as a novel prognostic marker in gastric cancer based on immunohistochemistry and statistical analysis. HOXA13 expression was significantly up-regulated in cancerous tissues compared with the corresponding non-cancerous mucosa (P < 0.001). Up-expression of HOXA13 was significantly correlated with T stage (P = 0.002), M stage (P = 0.024), advanced UICC stage (P < 0.001), histological differentiation (P = 0.005), and relapse (P = 0.001). Patients with positive HOXA13 expression had a obviously lower overall survival (OS) and disease-free survival (DFS) rate than patients with negative HOXA13 expression (HR 3.331, 95 % CI 1.722-6.442, P < 0.001; HR 3.289, 95 % CI 1.703-6.351, P < 0.001, respectively). Univariate and multivariate Cox analysis confirmed that HOXA13 could serve as a significant independent prognostic factor for DFS and OS. Therefore, our results indicated that several HOX genes might be closely involved in the process of the gastric tumorigenesis. Furthermore, up-expression of HOXA13 might be associated with highly aggressive phenotype of gastric cancer. HOXA13 was a significant independent prognostic factor and could serve as a putative biomarker for diagnosis and prognosis of gastric 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.

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.