Tumor-specific downregulation and methylation of the CDH13 (H-cadherin) and CDH1 (E-cadherin) genes correlate with aggressiveness of human pituitary adenomas

Clinicopathological significance and potential drug target of T-cadherin in NSCLC

Background

Previous studies demonstrate that T-cadherin is a candidate tumor suppressor in several types of human tumors, including non-small cell lung cancer (NSCLC). Lack of protein expression of T-cadherin by hypermethylation has been found to play an important role in lung alveolar differentiation regulation and epithelial tumorigenesis. However, the correlation between T-cadherin hypermethylation and clinicopathological characteristics of NSCLC remains unclear. Here we conducted a systematic review and meta-analysis to quantitatively evaluate the effects of T-cadherin hypermethylation on the incidence of NSCLC and clinicopathological characteristics.

Methods

A detailed literature search was carried out for related research publications. Analyses of pooled data were performed. Odds ratio (OR) and hazard ratio (HR) were calculated and summarized, respectively.

Results

Final analysis of 1,172 NSCLC patients from 15 eligible studies was performed. T-cadherin hypermethylation was observed to be significantly higher in NSCLC than in normal lung tissue, based on the pooled OR from nine studies including 532 NSCLC and 372 normal lung tissue samples (OR=8.19, 95% confidence interval [CI]=5.41–12.39, P<0.00001). T-cadherin hypermethylation may also be associated with pathological types. The pooled OR was obtained from four studies including 111patients with squamous cell carcinoma and 106 with adenocarcinoma (OR=0.35, 95% CI=0.19–0.66, P=0.001), which indicated that T-cadherin hypermethylation plays a more important role in the pathogenesis of adenocarcinoma. We did not find that T-cadherin hypermethylation was correlated with the sex or smoking status, clinical stages, or epidermal growth factor receptor (EGFR) mutation status. However, T-cadherin hypermethylation was found to be significantly higher in poorly differentiated NSCLC than in moderately and highly differentiated NSCLC, and NSCLC patients with T-cadherin hypermethylation had a lower survival rate than those without T-cadherin hypermethylation.

Conclusion

The results of this meta-analysis suggest that T-cadherin hypermethylation is associated with an increased risk and worse survival in NSCLC. T-cadherin hypermethylation, which induces the inactivation of T-cadherin gene, plays an important role in the carcinogenesis, cancer progression, as well as clinical outcome.

Prognostic significance of CDH13 hypermethylation and mRNA in NSCLC

Aberrant methylation of CpG dinucleotides is a commonly observed epigenetic modification in human cancer. Thus, detection of aberrant gene promoter methylation as a tool for diagnosis of tumors or as a prognostic marker has been widely described for many types of cancers, including nonsmall cell lung cancer (NSCLC). Emerging evidence indicates that CDH13 is a candidate tumor suppressor in several types of human tumors, including NSCLC. However, the correlation between CDH13 hypermethylation and clinicopathological characteristics of NSCLC remains unclear. In the current study, we conducted a systematic review and meta-analysis to quantitatively evaluate the effects of CDH13 hypermethylation on the incidence of NSCLC and clinicopathological characteristics. Final analysis of 803 NSCLC patients from eleven eligible studies was performed. CDH13 hypermethylation was observed to be significantly higher in NSCLC than in normal lung tissue, with the pooled odds ratio (OR) from seven studies including 448 NSCLC and 345 normal lung tissue (OR, 7.85; 95% confidence interval, 5.12-12.03; P<0.00001). CDH13 hypermethylation was also associated with pathological types. The pooled OR was obtained from four studies, including 111 squamous cell carcinoma and 106 adenocarcinoma (OR, 0.35; 95% confidence interval, 0.19-0.66; P=0.001), which indicated that CDH13 hypermethylation plays a more important role in the pathogenesis of adenocarcinoma. NSCLC with CDH13 hypermethylation was found more frequently in poorly differentiated NSCLC patients. NSCLC patients with CDH13 hypermethylation had a lower survival rate than those without CDH13 hypermethylation. In addition, CDH13 mRNA high expression was found to correlate with better overall survival for all NSCLC patients followed for 20 years (hazard ratio, 0.81; P=0.0056). Interestingly, CDH13 mRNA overexpression was found to correlate with better overall survival only in adenocarcinoma patients (hazard ratio, 0.42; P=9.6e-09), not in squamous cell carcinoma patients (hazard ratio, 0.93; P=0.59). The results of this meta-analysis suggest that CDH13 hypermethylation is associated with an increased risk and worse survival in NSCLC. CDH13 hypermethylation and mRNA expression play an important role in carcinogenesis, progression, and development, as well as clinical outcomes.

A pilot genome-scale profiling of DNA methylation in sporadic pituitary macroadenomas: association with tumor invasion and histopathological subtype

Pituitary adenomas (PAs) are neoplasms that may cause a variety of neurological and endocrine effects. Although known causal contributors include heredity, hormonal influence and somatic mutations, the pathophysiologic mechanisms driving tumorigenesis and invasion of sporadic PAs remain unknown. We hypothesized that alterations in DNA methylation are associated with PA invasion and histopathology subtype, and that genome-scale methylation analysis may complement current classification methods for sporadic PAs. Twenty-four surgically-resected sporadic PAs with varying histopathological subtypes were assigned dichotomized Knosp invasion scores and examined using genome-wide DNA methylation profiling and RNA sequencing. PA samples clustered into subgroups according to functional status. Compared with hormonally-active PAs, nonfunctional PAs exhibited global DNA hypermethylation (mean beta-value 0.47 versus 0.42, P = 0.005); the most significant site of differential DNA methylation was within the promoter region of the potassium voltage-gated channel KCNAB2 (FDR = 5.11×10⁻¹⁰). Pathway analysis of promoter-associated CpGs showed that nonfunctional PAs are potentially associated with the ion-channel activity signal pathway. DNA hypermethylation tended to be negatively correlated with gene expression. DNA methylation analysis may be used to identify candidate genes involved in PA function and may potentially complement current standard immunostaining classification in sporadic PAs. DNA hypermethylation of KCNAB2 and downstream ion-channel activity signal pathways may contribute to the endocrine-inactive status of nonfunctional PAs.

Genetic and epigenetic mutations of tumor suppressive genes in sporadic pituitary adenoma

Human pituitary adenomas are the most common intracranial neoplasms. Approximately 5% of them are familial adenomas. Patients with familial tumors carry germline mutations in predisposition genes, including AIP, MEN1 and PRKAR1A. These mutations are extremely rare in sporadic pituitary adenomas, which therefore are caused by different mechanisms. Multiple tumor suppressive genes linked to sporadic tumors have been identified. Their inactivation is caused by epigenetic mechanisms, mainly promoter hypermethylation, and can be placed into two groups based on their functional interaction with tumor suppressors RB or p53. The RB group includes CDKN2A, CDKN2B, CDKN2C, RB1, BMP4, CDH1, CDH13, GADD45B and GADD45G; AIP and MEN1 genes also belong to this group. The p53 group includes MEG3, MGMT, PLAGL1, RASSF1, RASSF3 and SOCS1. We propose that the tumor suppression function of these genes is mainly mediated by the RB and p53 pathways. We also discuss possible tumor suppression mechanisms for individual genes.

MicroRNAs in Human Pituitary Adenomas

MicroRNAs (miRNAs) are a class of recently identified noncoding RNAs that regulate gene expression at posttranscriptional level. Due to the large number of genes regulated by miRNAs, miRNAs play important roles in many cellular processes. Emerging evidence indicates that miRNAs are dysregulated in pituitary adenomas, a class of intracranial neoplasms which account for 10-15% of diagnosed brain tumors. Deregulated miRNAs and their targets contribute to pituitary adenomas progression and are associated with cell cycle control, apoptosis, invasion, and pharmacological treatment of pituitary adenomas. To provide an overview of miRNAs dysregulation and functions of these miRNAs in pituitary adenoma progression, we summarize the deregulated miRNAs and their targets to shed more light on their potential as therapeutic targets and novel biomarkers.

Different levels of various glucocorticoid-regulated genes in corticotroph adenomas

Recently, correlations between corticotroph tumor dedifferentiation and both E-cadherin immunostaining and reduced mRNA expression of the E-cadherin gene (CDH1) have been demonstrated. The purpose of this study was to explore whether tumor dedifferentiation correlated with glucocorticoid resistance and whether the resistance was associated with both positively and negatively regulated genes. Tumor material from 20 patients with verified Cushing's disease or Nelson's syndrome operated on at Rikshospitalet, Oslo. Reverse transcription polymerase chain reaction analysis of genes such as E-cadherin (CDH1), proopiomelanocortin (POMC), glucocorticoid-induced leucine zipper (GILZ), and thioredoxin-interacting protein (TXNIP) was performed. The correlations between the expression of the GILZ, TXNIP, and POMC genes in different stages of corticotroph adenomas, the E-cadherin mRNA expression and staining pattern, and the preoperative 24-h cortisol excretion were examined. The GILZ and TXNIP expression levels were positively correlated to the CDH1 expression and were highest in microadenomas and in tumors with a high membranous E-cadherin reactivity. In contrast, the POMC expression was not significantly different between the groups. This divergence between the genes that were positively and negatively regulated by glucocorticoids could not be supported by other gene expression analyses. No correlations to urinary cortisol were found. The expression of the glucocorticoid-responsive genes POMC, GILZ, and TXNIP in corticotroph adenomas showed a remarkable variation. The pattern and variability of glucocorticoid resistance in corticotroph adenomas seem to correlate with a loss of the epithelial phenotype associated with corticotroph tumor dedifferentiation.

Silencing of RASSF3 by DNA hypermethylation is associated with tumorigenesis in somatotroph adenomas

The pathogenic mechanisms underlying pituitary somatotroph adenoma formation, progression are poorly understood. To identify candidate tumor suppressor genes involved in pituitary somatotroph adenoma tumorigenesis, we used HG18 CpG plus Promoter Microarray in 27 human somatotroph adenomas and 4 normal human adenohypophyses. RASSF3 was found with frequent methylation of CpG island in its promoter region in somatotroph adenomas but rarely in adenohypophyses. This result was confirmed by pyrosequencing analysis. We also found that RASSF3 mRNA level correlated negatively to its gene promoter methylation level. RASSF3 hypermethylation and downregulation was also observed in rat GH3 and mouse GT1.1 somatotroph adenoma cell lines. 5-Aza-2′ deoxycytidine and trichostatin-A treatment induced RASSF3 promoter demethylation, and restored its expression in GH3 and GT1.1 cell lines. RASSF3 overexpression in GH3 and GT1.1 cells inhibited proliferation, induced apoptosis accompanied by increased Bax, p53, and caspase-3 protein and decreased Bcl-2 protein expression. We also found that the antitumor effect of RASSF3 was p53 dependent, and p53 knockdown blocked RASSF3-induced apoptosis and growth inhibition. Taken together, our results suggest that hypermethylation-induced RASSF3 silencing plays an important role in the tumorigenesis of pituitary somatotroph adenomas.

Expression and Significance of E-Cadherin and β-Catenins in Pituitary Adenoma

This study used immunohistochemical methods for detecting the expression of E-cadherin and β-catenin in pituitary adenoma. Specimens were collected from 91 cases. EnVision was used for immunohistochemical staining. The results were graded depending on the staining intensity and range. Associations between E-cadherin and β-catenin expression and tumor subtype, invasiveness, and postoperative recurrence were investigated. There was a significant downregulation of E-cadherin and β-catenin in growth hormone (GH)-type tumors when compared with prolactin-type tumors ( uc = 2.693 and 2.109, respectively; P < .05). E-cadherin and β-catenin were downregulated in invasive pituitary adenomas ( uc = 3.563 and 4.166, respectively; P < .05) and in clinically recurring pituitary adenomas ( uc = 2.871 and 3.866, respectively; P < .05). There was no difference in the percentage of invasive prolactin and GH secreting tumors (28.57% and 22.86%, respectively; P > .05). The expression of E-cadherin and β-catenin in pituitary adenoma was significantly downregulated and related to subtype, invasiveness, and postoperative recurrence.

The significance of epigenetic alterations in lung carcinogenesis

Lung cancer is recognized as a leading cause of cancer-related death worldwide and its frequency is still increasing. The prognosis in lung cancer is poor and limited by the difficulties of diagnosis at early stage of disease, when it is amenable to surgery treatment. Therefore, the advance in identification of lung cancer genetic and epigenetic markers with diagnostic and/or prognostic values becomes an important tool for future molecular oncology and personalized therapy. As in case of other tumors, aberrant epigenetic landscape has been documented also in lung cancer, both at early and late stage of carcinogenesis. Hypermethylation of specific genes, mainly tumor suppressor genes, as well as hypomethylation of oncogenes and retrotransposons, associated with histopathological subtypes of lung cancer, has been found. Epigenetic aberrations of histone proteins and, especially, the lower global levels of histone modifications have been associated with poorer clinical outcome in lung cancer. The recently discovered role of epigenetic modifications of microRNA expression in tumors has been also proven in lung carcinogenesis. The identified epigenetic events in lung cancer contribute to its specific epigenotype and correlated phenotypic features. So far, some of them have been suggested to be cancer biomarkers for early detection, disease monitoring, prognosis, and risk assessment. As epigenetic aberrations are reversible, their correction has emerged as a promising therapeutic target.

ADAM10 promotes pituitary adenoma cell migration by regulating cleavage of CD44 and L1

ADAM10 is a metalloproteinase that regulates invasiveness in many tumors. Here, we found that ADAM10 expression correlates with the invasiveness of pituitary adenomas and contributes to invasion by cleaving L1 and CD44. In high-grade pituitary adenoma patients, ADAM10 expression levels were found to be elevated compared with low-grade pituitary adenomas. In a phorbol 12-myristate 13-acetate (PMA)-stimulated pituitary adenoma cell line, AtT-20 cells, we found that the cleavage of L1 was correspondingly enhanced with the increased interaction between Src and Shc. Increases in PMA-induced L1 cleavage and the phosphorylation of residue 418 of Src (418Src) were promoted by overexpression of ADAM10. Inversely, knockdown of Adam10 suppressed PMA-induced L1 cleavage and the phosphorylation of Src, which was blocked by the Src inhibitor PP2 and the MEK inhibitor PD98059. On the other hand, calcium flux activation in AtT-20 cells resulted in increased CD44 cleavage, with reduction of the interaction between calmodulin and ADAM10. The induction of enhanced CD44 cleavage by calcium flux activation was inhibited by knockdown of Adam10. In addition, Adam10 knockdown repressed AtT-20 cell migration, which was reversed by CD44EXT (CD44 ectodomain cleavage). Collectively, these data indicated that ADAM10 facilitated cell migration through modulation of CD44 and L1 cleavage.

DNA methylation based biomarkers: practical considerations and applications

A biomarker is a molecular target analyzed in a qualitative or quantitative manner to detect and diagnose the presence of a disease, to predict the outcome and the response to a specific treatment allowing personalized tailoring of patient management. Biomarkers can belong to different types of biochemical molecules such as proteins, DNA, RNA or lipids, whereby protein biomarkers have been the most extensively studied and used, notably in blood-based protein quantification tests or immunohistochemistry. The rise of interest in epigenetic mechanisms has allowed the identification of a new type of biomarker, DNA methylation, which is of great potential for many applications. This stable and heritable covalent modification mostly affects cytosines in the context of a CpG dinucleotide in humans. It can be detected and quantified by a number of technologies including genome-wide screening methods as well as locus- or gene-specific high-resolution analysis in different types of samples such as frozen tissues and FFPE samples, but also in body fluids such as urine, plasma, and serum obtained through non-invasive procedures. In some cases, DNA methylation based biomarkers have proven to be more specific and sensitive than commonly used protein biomarkers, which could clearly justify their use in clinics. However, very few of them are at the moment used in clinics and even less commercial tests are currently available. The objective of this review is to discuss the advantages of DNA methylation as a biomarker, the practical considerations for their development, and their use in disease detection, prediction of outcome or treatment response, through multiple examples mainly focusing on cancer, but also to evoke their potential for complex diseases and prenatal diagnostics.

Reduced levels of E-cadherin correlate with progression of corticotroph pituitary tumours

OBJECTIVES

Loss of E-cadherin is an important marker of epithelial tumour progression. The aims of this study were to explore whether E-cadherin expression and localization correlate to corticotroph tumour progression, relate the expression of the E-cadherin gene (CDH1) to immunohistochemical E-cadherin staining pattern, and study whether the E-cadherin levels were correlated to methylation status of the CDH1 promoter region.

DESIGN

Immunohistochemical analyses of E-cadherin protein were performed, as was RT-qPCR of the CDH1 and the POMC genes. Methylation pattern of the promoter region of CDH1 was measured using pyrosequencing of bisulfite-treated DNA.

PATIENTS

Forty-five patients operated at a tertiary referral centre in Oslo, Norway. Adenoma tissue sections and RNA samples from patients with verified Cushing's disease or Nelson's syndrome were collected.

MEASUREMENTS

Expression of E-cadherin mRNA and protein in pituitary corticotroph adenomas and average percentage of methylated cytosines in a cytosine-phosphate-guanosine island of the CDH1 promoter.

RESULTS

Correlations were observed between tumour progression and both nuclear expression of E-cadherin and reduced CDH1 mRNA. The E-cadherin expression was not determined by the methylation pattern of the CDH1 promoter.

CONCLUSIONS

Corticotroph tumour progression was associated with reduced expression of the epithelial marker E-cadherin.

Methylator phenotype of malignant germ cell tumours in children identifies strong candidates for chemotherapy resistance

BACKGROUND

Yolk sac tumours (YSTs) and germinomas are the two major pure histological subtypes of germ cell tumours. To date, the role of DNA methylation in the aetiology of this class of tumour has only been analysed in adult testicular forms and with respect to only a few genes.

METHODS

A bank of paediatric tumours was analysed for global methylation of LINE-1 repeat elements and global methylation of regulatory elements using GoldenGate methylation arrays.

RESULTS

Both germinomas and YSTs exhibited significant global hypomethylation of LINE-1 elements. However, in germinomas, methylation of gene regulatory regions differed little from control samples, whereas YSTs exhibited increased methylation at a large proportion of the loci tested, showing a 'methylator' phenotype, including silencing of genes associated with Caspase-8-dependent apoptosis. Furthermore, we found that the methylator phenotype of YSTs was coincident with higher levels of expression of the DNA methyltransferase, DNA (cytosine-5)-methyltransferase 3B, suggesting a mechanism underlying the phenotype.

CONCLUSION

Epigenetic silencing of a large number of potential tumour suppressor genes in YSTs might explain why they exhibit a more aggressive natural history than germinomas and silencing of genes associated with Caspase-8-dependent cell death might explain the relative resistance of YSTs to conventional therapy.

Promoter methylation of H-cadherin is a potential biomarker in patients with bladder transitional cell carcinoma

OBJECTIVES

H-cadherin, functions as a tumor suppressor, is frequently silenced by promoter methylation in human cancers. The aim of this study was to evaluate the feasibility of using H-cadherin methylation in tumor tissues as a potential biomarker in patients with bladder transitional cell carcinoma (TCC).

MATERIALS AND METHODS

We examined the methylation status of H-cadherin in 133 primary bladder TCC samples and 43 normal bladder epithelial tissues using methylation-specific polymerase chain reaction (MSP) and then analyzed the associations between H-cadherin methylation and clinicopathologic features as well as patients' outcome.

RESULTS

H-cadherin methylation was detected in 47 (35.3%) bladder TCC samples, but not found in controls (P = 0.0000). Moreover, H-cadherin methylation was significantly associated with advanced stage (P = 0.0006), high grade (P = 0.0165), larger tumor size (P = 0.0225), tumor recurrence (P = 0.0106), and poor prognosis (P = 0.0000). In addition, multivariate analysis indicated that H-cadherin methylation is independently associated with poor outcome and had a relative risk of death of 3.832 (P = 0.0071, 95% confidence interval: 1.443-10.176).

CONCLUSIONS

The results suggest that H-cadherin methylation may be used as a potential biomarker for the malignancy of bladder TCC and as an independent prognostic biomarker in patients with bladder TCC.

Impact of MTHFR gene C677T polymorphism on Bcl-2 gene methylation and protein expression in colorectal cancer

OBJECTIVE

To investigate the impact of MTHFR C677T polymorphism on Bcl-2 gene promoter CpG island (CGI) methylation and Bcl-2 protein expression.

MATERIAL AND METHODS

MTHFR polymorphisms of 86 sporadic colorectal cancer (CRC) patients and 100 healthy volunteers were analyzed by PCR-based restriction fragment length polymorphism, and Bcl-2 promoter CGI methylation in 86 CRC tissues and 86 paired nonneoplastic adjacent tissues was determined by methylation-specific PCR. Bcl-2 oncoprotein expression in 70 CRC tissues and paired nonneoplastic adjacent tissues was detected by immunohistochemistry.

RESULTS

The frequency of MTHFR 677 T allele and combined variant genotypes (677CT + TT) in CRC patients was significantly higher than that in healthy controls (p = 0.023 and p = 0.035, respectively), and there is a significant association between 677TT or 677(CT + TT) genotypes and CRC (OR = 2.534, p = 0.045 and OR = 1.888, p = 0.035, respectively). The frequency of methylated Bcl-2 promoter CGI in tumor tissues was significantly lower than that in nonneoplastic adjacent tissues (p = 0.014). The frequency of methylated Bcl-2 promoter CGI in CRC tissues of the individuals with CC genotype was significantly higher than that of those with CT/TT genotypes (p = 0.018), there was significant distribution difference of C and T alleles between individuals with methylated and unmethylated Bcl-2 promoter CGI in colorectal cancer tissues (p = 0.023). Bcl-2 promoter hypomethylation was significantly correlated with Bcl-2 oncoprotein expression in colorectal cancer tissues (r = 0.558, p < 0.001).

CONCLUSION

Bcl-2 promoter is hypomethylated in colorectal cancer tissue, and there is a significant correlation between MTHFR 677 TT or CT/TT genotypes and CRC or Bcl-2 promoter CGI methylation/oncoprotein expression in CRC.

Cadherin 13 in cancer

We review the evidence suggesting the involvement of Cadherin 13 (CDH13, T-cadherin, H-cadherin) in various cancers. CDH13 is an atypical member of the cadherin family, devoid of a transmembrane domain and anchored to the exterior surface of the plasma membrane via a glycosylphosphatidylinositol anchor. CDH13 is thought to affect cellular behavior largely through its signaling properties. It is often down-regulated in cancerous cells. CDH13 down-regulation has been associated with poorer prognosis in various carcinomas, such as lung, ovarian, cervical and prostate cancer. CDH13 re-expression in most cancer cell lines inhibits cell proliferation and invasiveness, increases susceptibility to apoptosis, and reduces tumor growth in in vivo models. These properties suggest that CDH13 may represent a possible target for therapy in some cancers. At the same time, CDH13 is up-regulated in blood vessels growing through tumors and promotes tumor neovascularization. In contrast to most cancer cell lines, CDH13 overexpression in endothelial cells promotes their proliferation and migration, and has a pro-survival effect. We also discuss molecular mechanisms that may regulate CDH13 expression and underlie its roles in cancer.

The expression of E-cadherin in somatotroph pituitary adenomas is related to tumor size, invasiveness, and somatostatin analog response

CONTEXT

Appropriate cell-to-cell adhesion is fundamental for the epithelial phenotype of pituitary cells. Loss of the adhesion protein E-cadherin has been associated with invasiveness, metastasis, and poor prognosis in cancers of epithelial origin. In somatotroph adenomas, a variable and reduced expression of E-cadherin has been demonstrated. In addition, nuclear translocation of E-cadherin was found to correlate with pituitary tumor invasion.

OBJECTIVE

The objective was to examine the protein expression of E-cadherin in somatotroph pituitary adenomas in relation to adenoma size, invasiveness, and somatostatin analog (SMS) efficacy.

PATIENTS AND METHODS

Eighty-three patients were included, and 29 were treated preoperatively with SMS. Adenoma E-cadherin protein expression was analyzed by Western blot (61 patients) and immunohistochemistry (IHC) (80 patients) with antibodies directed against both extracellular and intracellular domains (IHC). The acute (direct surgery group) and long-term (preoperatively treated group) SMS responses were evaluated. Baseline tumor volume and invasiveness were measured on magnetic resonance imaging scans.

RESULTS

Membranous E-cadherin was lost in several adenomas. Nine of these were nuclear E-cadherin positive. The E-cadherin protein expression correlated negatively to tumor size and positively to acute SMS response. Low E-cadherin levels (preoperatively treated group only) and loss of membranous E-cadherin correlated to tumor invasiveness. The E-cadherin level correlated positively to tumor reduction after SMS treatment, and adenomas with nuclear E-cadherin staining had lower IGF-I reduction and tumor shrinkage. Preoperatively treated adenomas had reduced E-cadherin protein levels, but the IHC expression was unaltered.

CONCLUSION

Reduced E-cadherin expression may correlate to a dedifferentiated phenotype in the somatotroph pituitary adenomas.

Expression of extracellular matrix-proteins in perisellar connective tissue and dura mater

PURPOSE

To describe the pattern of expression of extracellular matrix (ECM) proteins in perisellar connective tissue.

METHODS

Dural and perisellar specimens from ten individuals were investigated immunohistochemically for collagens I to IV, tenascin, fibronectin, elastin, laminin, and vitronectin.

FINDINGS

Collagen I and III and fibronectin were strongly expressed and collagen IV, tenascin, and vitronectin were moderately expressed in the boundaries of the sella and around the CS. In six of nine specimens from the anterior boundary of the sella, and in 11 of 19 samples from the lateral boundary of the sella (medial wall of CS), two different layers could be detected by the expression of different ECM proteins. None of the antigens generally allowed differentiation between two layers of the pituitary envelope.

CONCLUSIONS

The pituitary boundary may consist of a single or a double layer, infrequently differentiated from each other by the expression of different ECM proteins.

Expression and clinical significance of p120 catenin mRNA and protein in pancreatic carcinoma

The aim of this work was investigate the association of P120 catenin expression with the clinicopathologic features and prognosis of pancreatic carcinoma. RT-PCR was performed to investigate the expression of P120 catenin mRNA and western blotting were performed to investigate the expression of P120 catenin protein in 52 patients with pancreatic carcinoma. The relationships between P120 catenin expression and clinicopathological characteristics and prognosis were analyzed. The mRNA and protein expression of P120 catenin detected by RT-PCR and western blotting in pancreatic carcinoma was significantly lower than that in normal pancreatic tissues (0.227+/-0.067 vs 0.793+/-0.162, t=9.157, P =0.000; 0.665+/-0.192 vs 0.936+/-0.251, t=3.857, P=0.002). Reduced expression of P120 catenin mRNA and protein was significantly correlated with lymph node metastasis (P =0.004, P =0.006), vascular invasion (P =0.022, P =0.039 ), distant metastasis (P =0.037 , P =0.025), differentiated (P =0.033, P =0.013) and pTNM stage (P =0.003, P =0.022) of tumours. Additionally, reduced expression of P120 catenin mRNA and protein in tumour correlated with a worse prognosis and normal expression with a better survival rate (P=0.022, P=0.007). The reduced expression of both P120 catenin mRNA and protein in pancreatic carcinoma suggest that low expressions relate to pancreatic carcinoma development. P120 catenin may be related to pancreatic carcinoma behaviour and be a potential prognostic molecule.

Altered gene expression and miRNA expression associated with cancerous IEC-6 cell transformed by MNNG

Background

Tumorigenesis is thought to be the consequence of gene mutation and disordered gene expression. However, the detailed molecular mechanism underlying the development and progress of colon cancer have not been elucidate completely. This study aimed to find out the genes associated with cancer biological pathways involved in transformation and tumorigenesis.

Methods

Normal intestinal cell line 6 (IEC-6) cells were transformed to cancer cells by treatment with cancerogenic agent of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and Phorbol 12-myristate 13 acetate (PMA). Then we investigated the altered gene expression of transformed IEC-6 cells by the microarray containing 113 genes associated with cancer pathway. Also the altered miRNAs of transformed IEC-6 cells were analyzed by array hybridization (miRCURY Array v9.2, Exiqon). The levels of acetylated histone H3 in transformed IEC-6 cells was evaluated by western blot.

Results

Cell proliferation was significantly increased as IEC-6 cells were transformed and tumor xenografts could be detected in animals as transformed IEC-6 cells were inoculated subcutaneously in nude mice. Result of microarray showed nine genes were increased and two decreased, as well as 13 miRNA were increased and 97 decreased. Verification by real-time PCR implies that the data obtained from microarray analysis were reliable. Western blot showed the levels of acetylated histone H3 were increased dramatically after MNNG/PMA treatment.

Conclusion

Our results showed many important biological pathways and miRNAs were involved in transformation and tumorigenesis of IEC-6 cells, which suggested the transformation of normal cells was involved with large mount of genetic and epigenetic variation.

Nuclear accumulation of e-cadherin correlates with loss of cytoplasmic membrane staining and invasion in pituitary adenomas

CONTEXT

Loss of the cell adhesion protein E-cadherin is associated with invasion and metastasis in a number of malignancies. Recent studies have highlighted that loss of E-cadherin cell membrane expression may be accompanied by its detection in the nucleus, suggesting cellular redistribution during neoplasia. Pituitary tumors, although typically benign, may be locally invasive, and loss of membranous E-cadherin has been reported as a marker of invasion in prolactinomas.

OBJECTIVE

Our objective was to study E-cadherin expression in pituitary adenomas, specifically whether nuclear redistribution occurs in this setting.

METHODS

Immunohistochemistry, RT-PCR, and direct sequencing were performed.

RESULTS

Strong cytoplasmic membrane staining was present in all eight normal samples but completely absent in 21 of 44 adenomas (48%) with weak staining in an additional 11 adenomas using an antibody against the extracellular domain of E-cadherin. To identify nuclear translocation of the protein, immunohistochemistry was performed using an antibody against the cytoplasmic domain. Nuclear staining was present in 38 of 44 adenomas (86%) and absent in normal tissue. Nuclear E-cadherin inversely correlated with loss of E-cadherin cytoplasmic membrane staining and was associated with tumor invasion (P = 0.009). To investigate the mechanism of nuclear redistribution of E-cadherin, we performed RT-PCR of mRNA and sequenced tumor DNA. E-cadherin mRNA expression was reduced in only one of 30 samples (3%). No mutations were detected.

CONCLUSIONS

E-cadherin was frequently lost at the cytoplasmic membrane but detected in the nucleus, suggesting that cleavage of the extracellular domain and nuclear translocation of E-cadherin is a common event that may determine local invasion in pituitary adenomas.

Overexpression of HMGA2 relates to reduction of the let-7 and its relationship to clinicopathological features in pituitary adenomas

High-mobility group A2 is highly expressed during embryogenesis and in various benign and malignant tumors. Recent studies report that high-mobility group A2 is negatively regulated by the let-7 microRNAs (miRNAs) family in vitro. The development of pituitary adenomas in high-mobility group A2 transgenic mice showed that high-mobility group A2 may be involved in pituitary tumorigenesis. However, no studies have investigated the clinical significance of high-mobility group A2 and its relationship to the let-7 miRNA family in human pituitary adenomas. Using immunohistochemistry, we analyzed high-mobility group A2 expression with respect to various clinicopathologic factors in 98 pituitary adenomas. Overexpression of high-mobility group A2 was observed in 39% (38/98) of pituitary adenomas compared with normal adenohypophysial tissue and was frequently found in adenomas including prolactin (PRL), adrenocorticotrophic hormone, or follicle-stimulating hormone/luteinizing hormone and in null cell adenomas, but relatively rare in growth hormone (GH) and mixed GH/PRL adenomas. High-mobility group A2 expression was significantly associated with tumor invasion (P<0.05) and was significantly higher in grade IV than in grades I, II, and III adenomas (P<0.05). High levels of high-mobility group A2 expression were more frequently observed in macroadenomas than in microadenomas (P<0.05). High levels of high-mobility group A2 expression also significantly correlated with the proliferation marker Ki-67 (P<0.0001). Real-time quantitative RT-PCR analysis was carried out to evaluate the expression of let-7 in 55 pituitary adenomas. Subsequently, decreased expression of let-7 was confirmed in 23 of 55 (42%) adenomas and was correlated with high-grade tumors (P<0.05). An inverse correlation between let-7 and high-mobility group A2 expression was evident (R=-0.33, P<0.05). These findings support a causal link between let-7 and high-mobility group A2 whereby loss of let-7 expression induces high-mobility group A2 upregulation that represents an important mechanism in pituitary tumorigenesis and progression.

Pituitary gland and beta-catenin signaling: from ontogeny to oncogenesis

Although pituitary tumors are mostly benign, they share certain molecular events with more malignant neoplasia, although their precise pathogenesis is far from established. The acquisition of new functional characteristics during their evolution suggests a multistep process that leads to tumor transformation. Mutations in classical tumor suppressor genes or oncogenes are infrequently associated with pituitary tumorigenesis. However, alterations in different signaling pathways, especially those involved in pituitary gland development, have emerged as significant features in pituitary adenomas. In particular, changes in inhibitory components of the beta-catenin pathway and its relationship to the cadherin family of peptides may well play an important role in tumorigenesis. We review and assess the role of the beta-catenin signaling pathway in the pathogenesis of pituitary adenomas.

DNA methylation patterns in bladder cancer and washing cell sediments: a perspective for tumor recurrence detection

Background

Epigenetic alterations are a hallmark of human cancer. In this study, we aimed to investigate whether aberrant DNA methylation of cancer-associated genes is related to urinary bladder cancer recurrence.

Methods

A set of 4 genes, including CDH1 (E-cadherin), SFN (stratifin), RARB (retinoic acid receptor, beta) and RASSF1A (Ras association (RalGDS/AF-6) domain family 1), had their methylation patterns evaluated by MSP (Methylation-Specific Polymerase Chain Reaction) analysis in 49 fresh urinary bladder carcinoma tissues (including 14 cases paired with adjacent normal bladder epithelium, 3 squamous cell carcinomas and 2 adenocarcinomas) and 24 cell sediment samples from bladder washings of patients classified as cancer-free by cytological analysis (control group). A third set of samples included 39 archived tumor fragments and 23 matched washouts from 20 urinary bladder cancer patients in post-surgical monitoring. After genomic DNA isolation and sodium bisulfite modification, methylation patterns were determined and correlated with standard clinic-histopathological parameters.

Results

CDH1 and SFN genes were methylated at high frequencies in bladder cancer as well as in paired normal adjacent tissue and exfoliated cells from cancer-free patients. Although no statistically significant differences were found between RARB and RASSF1A methylation and the clinical and histopathological parameters in bladder cancer, a sensitivity of 95% and a specificity of 71% were observed for RARB methylation (Fisher's Exact test (p < 0.0001; OR = 48.89) and, 58% and 17% (p < 0.05; OR = 0.29) for RASSF1A gene, respectively, in relation to the control group.

Conclusion

Indistinct DNA hypermethylation of CDH1 and SFN genes between tumoral and normal urinary bladder samples suggests that these epigenetic features are not suitable biomarkers for urinary bladder cancer. However, RARB and RASSF1A gene methylation appears to be an initial event in urinary bladder carcinogenesis and should be considered as defining a panel of differentially methylated genes in this neoplasia in order to maximize the diagnostic coverage of epigenetic markers, especially in studies aiming at early recurrence detection.

Reduction of GSTP1 expression by DNA methylation correlates with clinicopathological features in pituitary adenomas

Pi-class glutathione-S-transferase (GSTP1) located on chromosome 11q13 encodes a phase II metabolic enzyme that detoxifies reactive electrophilic intermediates. GSTP1 plays an important role in the protecting cells from cytotoxic and carcinogenic agents and is expressed in normal tissues at variable levels in different cell types. Altered GSTP1 activity and expression have been reported in many tumors and this is largely due to GSTP1 DNA hypermethylation. The role of GSTP1 in pituitary tumorigenesis has not been investigated. In this study, we evaluated the GSTP1 expression level and GSTP1 DNA methylation status in a series of pituitary adenomas. Using immunohistochemistry, we identified expression of GSTP1 in all of the various normal hormone-producing adenohypophysial cell types. In pituitary adenomas, loss or reduced expression of GSTP1 was detected in 27 of 53 tumors (50.9%). Expression of GSTP1 was significantly lower in invasive adenomas than in noninvasive adenomas (P<0.05). Using methylation-specific polymerase chain reaction (MS-PCR), GSTP1 DNA promoter hypermethylation was detected in adenomas (38 of 53, 71.7%) but not in normal tissues. GSTP1 methylation was more frequent in grade II, III, and IV tumors (66.7, 85, and 83%, respectively) than in grade I tumors (33%, P<0.05). In addition, the frequency of GSTP1 methylation was higher in invasive tumors (85%) than in noninvasive tumors (59%; P<0.05). Methylation status correlated with significant downregulation of GSTP1 expression; the frequency of GSTP1 methylation was higher in tumors with reduced-GSTP1 expression (85%) than in tumors with normal or high GSTP1 expression (54%; P<0.05). These data indicate that GSTP1 inactivation through CpG hypermethylation is common in pituitary adenomas and may contribute to aggressive pituitary tumor behavior.

Reduced expression of P120 catenin in cholangiocarcinoma correlated with tumor clinicopathologic parameters

AIM: To investigate the relationship between the expression of P120 and the clinicopathologic parameters in intrahepatic cholangiocarcinoma (ICC).

METHODS: An immunohistochemical study of E-cadherin and P120 catenin was performed on 42 specimens of ICC with a Dako Envision kit.

RESULTS: The expression of E-cadherin and P120 was reduced in 27 cases (64.3%) and 31 cases (73.8%), respectively. Both E-cadherin and P120 expressions were significantly correlated with the tumor histological grade (χ² = 9.333, P = 009 and χ² = 11.71, P = 0.003), TNM stage (χ²= 8.627, P = 0.035 and χ² = 13.123, P = 0.004), intrahepatic metastasis (χ²= 7.292, P = 0.007 and χ² = 4.657, P = 0.041, respectively) and patients’ survival (χ²= 6.351, P = 0.002 and χ² = 4.023, P = 0.000, respectively). In addition, the expression of P120 was in concordance with that of E-cadherin (χ² = 13.797, P = 0.000), indicating that the expression of P120 may be dependent on that of E-cadherin. Finally, only P120 expression was found to be an independent prognostic factor in Cox regression model (r = 0.088, P = 0.049).

CONCLUSION: Down-regulated expression of E-cadherin and P120 occurs frequently in ICC and contributes to the progression and development of tumor. Both of them may be valuable biologic markers for predicting tumor invasion, metastasis and patients’ survival, but only P120 is an independent prognostic factor for ICC.