Human kallikrein-related peptidase 12 (KLK12) splice variants expression in breast cancer and their clinical impact

Prognostic value of kallikrein-related peptidase 12 (KLK12) mRNA expression in triple-negative breast cancer patients

BACKGROUND

The serine protease KLK12 belongs to the human fifteen-member family of kallikrein-related peptidases. Differential expression accompanied by either increased or decreased enzymatic activity has been linked to several diseases including cancer. Triple-negative breast cancer (TNBC) represents a very aggressive subgroup of breast cancer with high tumor recurrence rates and poor patient prognosis. Here, we quantified the KLK12 mRNA expression levels in tumor tissue of TNBC patients and analyzed their prognostic value.

METHODS

In the present study, KLK12 mRNA expression in tumor tissue of TNBC patients (n = 116) was determined by quantitative real-time PCR assay. The association of KLK12 mRNA levels with clinical parameters, and patients' outcome was analyzed using Chi-square tests, Cox regression models and Kaplan-Meier survival analysis.

RESULTS

Positive, but low KLK12 mRNA levels were detected in about half of the cases (54 out of 116; 47%), the other samples were negative for KLK12 mRNA expression. No significant association was observed between KLK12 mRNA levels and clinicopathological variables (age, lymph node status, tumor size, and histological grade). In univariate Cox analyses, positive KLK12 mRNA expression was significantly associated with shortened disease-free survival (DFS; hazard ratio [HR] = 2.12, 95% CI = 1.19-3.78, p = 0.010) as well as overall survival (OS; HR = 1.91, 95% CI = 1.04-3.50, p = 0.037). In multivariable Cox analysis, including all clinical parameters plus KLK12 mRNA, the latter - together with age - remained an independent unfavorable predictive marker for DFS (HR = 2.33, 95% CI = 1.28-4.24, p = 0.006) and showed a trend towards significance in case of OS (HR = 1.80, 95% CI = 0.96-3.38, p = 0.066).

CONCLUSIONS

Positive KLK12 expression is remarkably associated with shortened DFS and OS, suggesting that KLK12 plays a tumor-supporting role in TNBC.

Knockdown of KLK12 inhibits viability and induces apoptosis in human colorectal cancer HT-29 cell line

Kallikrein-related peptidase 12 (KLK12) is overexpressed in cancer tissues including gastric, breast and prostate cancer. However, the role of KLK12 in colorectal cancer is not fully understood. In the present study, the level of KLK12 was determined by performing reverse transcription-polymerase chain reaction (RT-qPCR) in colorectal cancer tissues and cell lines. Lipofectamine^® 2000 was used to transfect HT-29 cells to overexpress and knockdown KLK12. Cell viability, migration, invasion and apoptosis were detected by MTT, wound healing, Transwell and flow cytometry assays, respectively. The mRNA and protein expression levels of EMT-associated proteins, apoptosis-associated proteins, phosphorylated adenosine monophosphate-activated protein kinase (p-AMPK) and phosphorylated mammalian target of rapamycin (p-mTOR) were determined by RT-qPCR and western blot analysis. It was identified that the KLK12 mRNA levels were increased significantly in colorectal cancer tissues and cell lines. KLK12 small interfering RNA inhibited cell viability, migration and invasion. Furthermore, epithelial-mesenchymal transition (EMT)-associated proteins were altered by siKLK12. Cell apoptosis was induced by KLK12 downregulation, which was demonstrated by the changes in apoptosis-associated proteins; however, KLK12 overexpression produced the opposite effect. SiKLK12 enhanced the expression of p-AMPK and suppressed the expression of p-mTOR, while KLK12 overexpression had the opposite effect. Promotion of KLK12 overexpression-induced cell viability was reversed by 5-aminoimidazole-4-carboxamide ribonucleotide, an activator of the AMPK signaling pathway, and rapamycin, a specific inhibitor of the mTOR signaling pathway. Taken together, the results of the present study indicated that KLK12 was overexpressed in colorectal cancer and may regulate cell behavior, potentially via the AMPK and mTOR pathways.

Kallikrein-related peptidases in lung diseases

Human tissue kallikreins (KLKs) are 15 members of the serine protease family and are present in various healthy human tissues including airway tissues. Multiple studies have revealed their crucial role in the pathophysiology of a number of chronic, infectious and tumour lung diseases. KLK1, 3 and 14 are involved in asthma pathogenesis, and KLK1 could be also associated with the exacerbation of this inflammatory disease caused by rhinovirus. KLK5 was demonstrated as an influenza virus activating protease in humans, and KLK1 and 12 could also be involved in the activation and spread of these viruses. KLKs are associated with lung cancer, with up- or downregulation of expression depending on the KLK, cancer subtype, stage of tumour and also the microenvironment. Functional studies showed that KLK12 is a potent pro-angiogenic factor. Moreover, KLK6 promotes malignant-cell proliferation and KLK13 invasiveness. In contrast, KLK8 and KLK10 reduce proliferation and invasion of malignant cells. Considering the involvement of KLKs in various physiological and pathological processes, KLKs appear to be potential biomarkers and therapeutic targets for lung diseases.

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.

The miRNA-kallikrein interaction: a mosaic of epigenetic regulation in cancer

The kallikrein-related peptidases (KLKs) constitute a family of 15 highly conserved serine proteases with trypsin- and chymotrypsin-like activities. Dysregulated expression and/or aberrant activation of KLKs has been linked to various pathophysiological processes, including cancer. Many KLKs have been identified as potential cancer biomarkers. microRNAs (miRNAs) are a class of small non-coding RNAs that regulate gene expression by pairing to the 3' untranslated region (UTR) of complimentary mRNA targets. miRNAs are dysregulated in many cancers, including prostate, kidney and ovarian cancers. Several studies have shown that miRNAs are involved in the post-transcriptional regulation of KLKs. However, recent evidence suggests that miRNAs can also act as downstream effectors of KLKs. In this review, we provide an update on the epigenetic regulation of KLKs by miRNAs. We also present recent experimental evidence that supports the regulatory role of KLKs on miRNA networks. The potential diagnostic and therapeutic applications of miRNA-kallikrein interactions are also discussed.

Roles of Smads Family and Alternative Splicing Variants of Smad4 in Different Cancers

Transforming Growth Factor β (TGF-β) is one of the most common secretory proteins which are recognized by membrane receptors joined to transcription regulatory factor. TGF-β signals are transduced by the Smads family that regulate differentiation, proliferation, early growth, apoptosis, homeostasis, and tumor development. Functional study of TGF-β signaling pathway and Smads role is vital for certain diseases such as cancer. Alternative splicing produces a diverse range of protein isoforms with unique function and the ability to react differently with various pharmaceutical products. This review organizes to describe the general study of Smads family, the process of alternative splicing, the general aspect of alternative splicing of Smad4 in cancer and the possible use of spliceoforms for the diagnosis and therapeutic purpose. The main aim and objective of this article are to highlight some particular mechanisms involving in alternatives splicing of cancer and also to demonstrate new evidence about alternative splicing in different steps given cancer initiation and progression.

Human kallikrein-related peptidase 12 (KLK12) splice variants discriminate benign from cancerous breast tumors

OBJECTIVES

As kallikrein-related peptidase 12 (KLK12) has been implicated in the cancer progression and alternative splicing plays significant role in this disease, the aim of this study was to examine the expression profile and the clinical impact of the KLK12 splice variants in breast cancer.

DESIGN AND METHODS

Total RNA was isolated and reverse transcripted from 141 tissues. Afterwards, quantitative real-time PCR were conducted, followed by the performance of the comparative CT (2-ΔΔCT) method for relative quantification, whilst their correlation with the clinicopathological features of breast malignancies were assessed by statistical analysis.

RESULTS

Both KLK12sv1/2 and KLK12sv3 showed higher expression in non-cancerous than in cancerous samples. KLKsv1/2 (P = 0.001) upregulated and KLK12sv3 (P < 0.001) downregulated in the malignant compared to the benign tumors and their discriminative ability was verified by ROC curve analysis. Moreover, KLK12sv3 was associated with grade (P = 0.012) and hormonal receptor status (P = 0.001). Furthermore, Kaplan-Meier and Cox regression analyses showed that patients with positive KLK12sv1/2 and KLK12sv3 levels presented a significantly longer disease-free survival (P = 0.014 and P = 0.013, respectively) and overall survival (P = 0.062 and P = 0.004, respectively).

CONCLUSIONS

Our results demonstrate the discriminative value of KLK12sv1/2 and KLK12sv3 between benign and malignant breast tumors as well as their potential favorable prognostic significance in breast adenocarcinoma.

Human kallikrein-related peptidase 12 stimulates endothelial cell migration by remodeling the fibronectin matrix

Kallikrein-related peptidase 12 (KLK12) is a kallikrein family peptidase involved in angiogenesis - a complex biological process in which the sprouting, migration and stabilization of endothelial cells requires extracellular matrix remodeling. To characterize the molecular mechanisms associated with KLK12's proangiogenic activity, we evaluated its ability to hydrolyze various matrix proteins. Our results show that KLK12 efficiently cleaved the human extracellular matrix proteins fibronectin and tenascin, both of which are involved in the regulation of endothelial cell adhesion and migration. For fibronectin, the major proteolytic product generated by KLK12 was a 29 kDa fragment containing the amino-terminal domain and the first five type I fibronectin-domains, which are essential for regulating fibronectin assembly. We also demonstrated that KLK12-mediated fibronectin proteolysis antagonizes fibronectin polymerization and fibronectin fibril formation by endothelial cells, leading to an increase in cell migration. Furthermore, a polyclonal antibody raised against KLK12's proteolytic cleavage site on fibronectin prevented the KLK12-dependent inhibition of fibronectin polymerization and the KLK12-mediated pro-migratory effect on endothelial cells. Taken as a whole, our results indicate that KLK12's proangiogenic effect is mediated through several molecular mechanisms.

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.

Transcriptome profiling of cancer and normal tissues from cervical squamous cancer patients by deep sequencing

Cervical cancer is the fourth leading cause of cancer mortality in women worldwide. High‑risk human papillomavirus infection is a major cause of cervical cancer. A previous study revealed the role of different oncogenes and tumor suppressors in cervical cancer initiation and progression. However, the complicated genetic network regulating cervical cancer remains largely unknown. The present study reported transcriptome sequencing analysis of three cervical squamous cell cancer tissues and paired normal cervical tissues. Transcriptomic analysis revealed that 2,519 genes were differently expressed between cervical cancer tissues and their corresponding normal tissues. Among these, 236 differentially expressed genes (DEGs) were statistically significant, including many DEGs that were novel in cervical cancer, including gastrulation brain homeobox 2,5‑hydroxytryptamine receptor 1D and endothelin 3. These 236 significant DEGs were highly enriched in 28 functional gene ontology categories. The Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis suggested involvement of these DEGs in multiple pathways. The present study provides a transcriptome landscape of cervical cancer in Chinese patients and an improved understanding of the genetic regulatory network in cervical cancer tumorigenesis.

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.

Transcriptome changes upon in vitro challenge with Mycobacterium bovis in monocyte-derived macrophages from bovine tuberculosis-infected and healthy cows

As innate immune cells, macrophages are expected to respond to mycobacterial infection equally in both Mycobacterium bovis-infected cows and healthy cows. We previously found that monocyte-derived macrophages (MDMs) from M. bovis-infected cows respond differently than MDMs from healthy cows when exposed to in vitro M. bovis challenge. We have now used the Agilent™ Bovine Gene Expression Microarray to examine transcriptional differences between these MDMs. At a high multiplicity of infection (10), in vitro challenge led to changes in several thousands of genes, with dysregulation at multiple orders of magnitude. For example, significant changes were seen for colony stimulating factor 3 (granulocyte) (CSF3), colony stimulating factor 2 (granulocyte-macrophage) (CSF2), and chemokine (C-C motif) ligand 20 (CCL20). Classical macrophage activation was also observed, although to a lesser degree in interleukin 12 (IL12) expression. For macrophages, kallikrein-related peptidase 12 (KLK12) and protease, serine, 2 (trypsin 2) (PRSS2), as well as a secreted protein, acidic, cysteine-rich (osteonectin) (SPARC)-centered matricellular gene network, were differentially expressed in infected animals. Finally, global transcriptome fold-changes caused by in vitro challenge were higher in healthy cows than in tuberculosis-positive cows, suggesting that healthy macrophages responded marginally better to in vitro infection. Macrophages from healthy and already infected animals can both be fully activated during M. bovis infection, yet there are differences between these macrophages: distinct expression pattern in matricellular proteins, and their different responses to in vitro infection.

SigFuge: single gene clustering of RNA-seq reveals differential isoform usage among cancer samples

High-throughput sequencing technologies, including RNA-seq, have made it possible to move beyond gene expression analysis to study transcriptional events including alternative splicing and gene fusions. Furthermore, recent studies in cancer have suggested the importance of identifying transcriptionally altered loci as biomarkers for improved prognosis and therapy. While many statistical methods have been proposed for identifying novel transcriptional events with RNA-seq, nearly all rely on contrasting known classes of samples, such as tumor and normal. Few tools exist for the unsupervised discovery of such events without class labels. In this paper, we present SigFuge for identifying genomic loci exhibiting differential transcription patterns across many RNA-seq samples. SigFuge combines clustering with hypothesis testing to identify genes exhibiting alternative splicing, or differences in isoform expression. We apply SigFuge to RNA-seq cohorts of 177 lung and 279 head and neck squamous cell carcinoma samples from the Cancer Genome Atlas, and identify several cases of differential isoform usage including CDKN2A, a tumor suppressor gene known to be inactivated in a majority of lung squamous cell tumors. By not restricting attention to known sample stratifications, SigFuge offers a novel approach to unsupervised screening of genetic loci across RNA-seq cohorts. SigFuge is available as an R package through Bioconductor.

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

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

The diagnostic and prognostic value of serum human kallikrein-related peptidases 11 in non-small cell lung cancer

The aim of this study was to explore the diagnostic and prognostic value of serum human kallikrein-related peptidases 11 (KLK11) level in non-small cell lung cancer (NSCLC). Serum specimens from 138 patients with NSCLC and 40 healthy controls were collected. The concentration of KLK11 was measured by enzyme-linked immunosorbent assay (ELISA). The concentration of KLK11 in NSCLC was significantly higher compared to that in the controls (P<0.01). The serum KLK11 levels decreased with stage, presence of lymph node, and distant metastases, regardless of histology, age, and sex. With a cutoff point of 1.05 ng/ml, KLK11 showed a good diagnostic performance for NSCLC. Univariate analysis revealed that NSCLC patients with serum high KLK11 had a longer overall survival (OS) and progression-free survival (PFS) than those with low KLK11 (HR of 0.36, P=0.002; HR of 0.46, P=0.009). Cox multivariate analysis indicated that KLK11 was an independent prognostic indicator of PFS and OS (HR of 0.53, P=0.042; HR of 0.48, P=0.037). Kaplan-Meier survival curves further confirmed that patients with high KLK11 have longer PFS and OS (P=0.003 and P=0.018, respectively). In conclusion, the measurement of KLK11 might be a useful diagnostic and prognostic test for NSCLC patients.

Angiogenesis stimulated by human kallikrein-related peptidase 12 acting via a platelet-derived growth factor B-dependent paracrine pathway

KLK12, a kallikrein peptidase, is thought to take part in the control of angiogenesis. Our analysis of the secretome of endothelial cells (ECs) that had been treated with KLK12 showed that KLK12 converts the extracellular matrix- or membrane-bound precursor of platelet-derived growth factor B (PDGF-B) into a soluble form. Both PDGF-B and vascular endothelial growth factor A (VEGF-A) take part in the induction of angiogenesis by KLK12 in a coculture model of angiogenesis that mimics endothelial tubule formation. We used a cellular approach to analyze the interplay between KLK12, PDGF-B, and VEGF-A and showed that release of PDGF-B by KLK12 leads to the fibroblast-mediated secretion of VEGF-A. This then stimulates EC differentiation and the formation of capillary tube-like structures. Thus, KLK12 favors the interaction of ECs and stromal cells. The released PDGF-B acts as a paracrine factor that modulates VEGF-A secretion by stromal cells, which ultimately leads to angiogenesis. Moreover, the genes encoding KLK12 and PDGFB are both expressed in ECs and up-regulated in tumor cells kept under hypoxic conditions, which is consistent with the physiological involvement of KLK12 in PDGF-B maturation.

Alternative splicing for diseases, cancers, drugs, and databases

Alternative splicing is a major diversification mechanism in the human transcriptome and proteome. Several diseases, including cancers, have been associated with dysregulation of alternative splicing. Thus, correcting alternative splicing may restore normal cell physiology in patients with these diseases. This paper summarizes several alternative splicing-related diseases, including cancers and their target genes. Since new cancer drugs often target spliceosomes, several clinical drugs and natural products or their synthesized derivatives were analyzed to determine their effects on alternative splicing. Other agents known to have modulating effects on alternative splicing during therapeutic treatment of cancer are also discussed. Several commonly used bioinformatics resources are also summarized.

Parallel overexpression and clinical significance of kallikrein-related peptidases 7 and 14 (KLK7KLK14) in colon cancer

Currently available colon cancer (CC) markers lack sensitivity and specificity. Kallikrein-related peptidases (KLKs) present a new class of biomarkers under investigation for diverse diseases, including cancer. KLKs are co-expressed in various tissues participating in proteolytic cascades. KLK7 in human tumours facilitates metastasis by degrading components of the extracellular matrix. KLK14 promotes tumourigenesis by activating proteinase-activated receptors. In the present study we examined the concomitant expression of KLK7 and KLK14 in245 colonic tissue specimens from 175 patients; 70 were pairs of cancerous-normal tissues, 31 were cancerous tissues and 74 were colonic adenomas. We used quantitative real-time PCR and proved that both genes are up-regulated in CC at the mRNA level. Receiver-operating characteristic (ROC) analysis of our results showed that both genes have discriminatory value between CC and adenoma tissues, with KLK14 obtaining greater distinguishing power (area under the curve [AUC]=0.708 for KLK14; AUC=0.669 for KLK7). Current work showed that the two genes are fairly co-expressed in all three types of colon tissues examined (normal rs=0.667, p<0.001, adenomas rs=0.373, p=0.001, carcinomas rs=0.478, p<0.001). KLK14 is associated with shorter disease-free survival (DFS) and overall survival (OS) of patients (p=0.003, p=0.016 respectively), whereas KLK7only with shorter DFS (p=0.004). KLK7 and KLK14 gene expression can be regarded as markers of poor prognosis for CC patients with discriminating power between CC and adenoma patients.

Kallikrein-related peptidase 6 (KLK6)gene expression in intracranial tumors

Kallikrein-related peptidases (KLKs) are emerging novel new biomarkers for prognosis, diagnosis and therapeutic intervention of cancer. Kallikrein-related peptidase 6 (KLK6) has the highest expression in normal brain among other tissues. Although its expression has been extensively studied in many types of cancer and in neurodegenerative diseases, very little is known for its expression in intracranial tumors. In the present study, 73 intracranial tumor samples were examined for KLK6 messenger ribunucleic acid (mRNA) gene expression using quantitative real-time polymerase chain reaction. Statistical analysis revealed the significant association of KLK6 expression with clinical and pathological parameters. Follow-up information was available for a median time of 20 months (range 1-59 months). KLK6 is expressed more frequently in tumors of high malignancy like the glioblastomas (70.6 %) and less in tumors of low malignancy like the meningiomas (12.5 %). KLK6 positive expression is associated with tumor grade (p < 0.001), malignancy status (p < 0.001), and tumor histologic type (p = 0.001). Cox proportional hazard regression model using univariate analysis revealed for the first time that positive KLK6 expression is a significant factor for disease-free survival (DFS; p = 0.041) of patients suffering from intracranial tumors. Kaplan-Meier survival curves demonstrated that negative KLK6 expression is significantly associated with longer DFS (p = 0.032). KLK6 gene expression may have clinical utility as a marker of unfavorable prognosis for intracranial tumors, and consequently, it could be used as target for therapeutic intervention.