Expression of E-, P-, n-cadherins and catenins in human bladder carcinoma cell lines

Identification of differentially expressed genes and biological pathways in bladder cancer

The purpose of the present study was to identify key genes and investigate the related molecular mechanisms of bladder cancer (BC) progression. From the Gene Expression Omnibus database, the gene expression dataset GSE7476 was downloaded, which contained 43 BC samples and 12 normal bladder tissues. GSE7476 was analyzed to screen the differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed for the DEGs using the DAVID database, and a protein-protein interaction (PPI) network was then constructed using Cytoscape software. The results of the GO analysis showed that the upregulated DEGs were significantly enriched in cell division, nucleoplasm and protein binding, while the downregulated DEGs were significantly enriched in ‘extracellular matrix organization’, ‘proteinaceous extracellular matrix’ and ‘heparin binding’. The results of the KEGG pathway analysis showed that the upregulated DEGs were significantly enriched in the ‘cell cycle’, whereas the downregulated DEGs were significantly enriched in ‘complement and coagulation cascades’. JUN, cyclin-dependent kinase 1, FOS, PCNA, TOP2A, CCND1 and CDH1 were found to be hub genes in the PPI network. Sub-networks revealed that these gene were enriched in significant pathways, including the ‘cell cycle’ signaling pathway and ‘PI3K-Akt signaling pathway’. In summary, the present study identified DEGs and key target genes in the progression of BC, providing potential molecular targets and diagnostic biomarkers for the treatment of BC.

CD300LG improves the cytotoxic activity of CIK

To investigate the effect of CD300LG-γ induction on the cytotoxic activity of CIK. Eukaryotic expression plasmid hCD300LG-γ/pEGFP-C3, which can express human CD300LG-γ, was constructed and transfected into CHO cells by lipofectamine. The expression of CD300LG-γ was confirmed by immunofluorescence, RT-PCR, and Western Blot. To produce CIK cells, human peripheral blood mononuclear cells (PBMC) were isolated and induced, respectively, by cell lysates extracted from hCD300LG-γ/CHO cells, pEGFP-C3/CHO cells, and CHO cells, concurrently with the standard CIK inductive agent. The cytotoxic activity of these CIK cells against hCD300LG-γ/CHO cells, pEGFP-C3/CHO cells, CHO cells, and K562 cells was tested. The results showed that eukaryotic expression of plasmid hCD300LG-γ/pEGFP-C3 was constructed and transfected into CHO cells successfully. After being induced by cell lysates, the cytotoxicity of hCD300LG-γ/CHO-CIK was improved compared with the other CIK cells. In particular, the activity of killing pEGFP-C3/CHO and CHO cells was improved significantly. Meanwhile, the activity of hCD300LG-γ/CHO-CIK killing K562 was improved significantly compared with the other CIK cells. The results indicated that hCD300LG-γ induction can significantly improve the killing activity of CIK cells.

Cell adhesion and urothelial bladder cancer: the role of cadherin switching and related phenomena

Cadherins are mediators of cell-cell adhesion in epithelial tissues. E-cadherin is a known tumour suppressor and plays a central role in suppressing the invasive phenotype of cancer cells. However, the abnormal expression of N- and P-cadherin ('cadherin switching', CS) has been shown to promote a more invasive and m̀alignant phenotype of cancer, with P-cadherin possibly acting as a key mediator of invasion and metastasis in bladder cancer. Cadherins are also implicated in numerous signalling events related to embryonic development, tissue morphogenesis and homeostasis. It is these wide ranging effects and the serious implications of CS that make the cadherin cell adhesion molecules and their related pathways strong candidate targets for the inhibition of cancer progression, including bladder cancer. This review focuses on CS in the context of bladder cancer and in particular the switch to P-cadherin expression, and discusses other related molecules and phenomena, including EpCAM and the development of the cancer stem cell phenotype.

Estrogen receptor β (ERβ) is a novel prognostic marker of recurrence survival in non-muscle-invasive bladder cancer potentially by inhibiting cadherin switch

OBJECTIVE

The function and significance of estrogen receptor β (ERβ) in bladder cancer remains a field of hot debate. In this study, we aimed to (a) evaluate ERβ as a novel prognostic marker of recurrence free survival; and (b) digest the underlying mechanism by elucidating the relationship between ERβ expression and cadherin switch.

METHODS

We examined the expression levels of ERβ, E-cadherin and N-cadherin in 42 initial non-muscle-invasive urothelial bladder carcinomas via immunohistochemistry. Correlation analysis was performed among ERβ expression, cadherin switch and recurrence free survival. Moreover, in vitro studies were performed to validate the identified correlation using two bladder cancer cell lines RT4 and 253J. Upon stimulation with an ERβ selective agonist diarylpropionitrile, E-cadherin, N-cadherin expressions; cell migration and invasion capacity were assessed.

RESULTS

Expression of ERβ protein was seen in 34 bladder cancer cases (80.9%), and 21 (50%) specimens showed non-cadherin switch (positive E-cadherin and negative N-cadherin). ERβ expression and the non-cadherin switch are both accompanied with better recurrence free survival. Also, the least ERβ expression was observed in specimens that undergo cadherin switch. Moreover, these results were consistent with our observations in bladder cancer RT4 and 253J cell lines studies. Diarylpropionitrile stimulation resulted in an increase in E-cadherin, a decrease in N-cadherin expression and abolished cell migration and invasion.

CONCLUSION

ERβ is a prognostic marker of recurrence free rate in non-muscle-invasive bladder cancer, potentially through suppressing cadherin switch, and may act as a potential target for bladder cancer therapy.

Inhibition of presenilins attenuates proliferation and invasion in bladder cancer cells through multiple pathways

OBJECTIVE

Presenilin (PS)/γ-secretase is a key protease that initiates various biological processes. We investigated the effect of PS/γ-secretase on the expression and inhibition of urothelial cell carcinoma of bladder (UCB) as a potential alternative therapeutic target for UCB.

MATERIALS AND METHODS

PS-1 and PS-2 were identified in normal and malignant human bladder transitional cells by immunohistochemistry. We blocked PSs using a PS/γ-secretase inhibitor N-(N-[3,5-difluorophenacetyl]-L-alanyl)-S-phenylglycine-t-butylester (DAPT), and the proliferative and invasive potential of UCB cells SW780, BIU-87, 5637, and T24, and human normal urothelial cell line SV-HUC-1 were analyzed using Western blot, cell viability test, flow cytometry, and transwell assay. All experiments were repeated at least 3 times.

RESULTS

Human bladder samples of UCB, SW780, BIU-87, 5637, and T24 cells expressed higher PS-1 compared with normal ones. Cell vitality test demonstrated that DAPT attenuated UCB cell proliferation more than SV-HUC-1. Flow cytometry and transwell assay showed that T24 cells were arrested at G1/S checkpoint and its invasive ability was impaired. Western blot assay markedly showed that protein levels of CD44-intracellular domain, insulinlike growth factor-1Rβ, extracellular regulated protein kinase 1/2, cyclin D1, proliferating cell nuclear antigen, and matrix metalloproteinase-9 were downregulated by DAPT, whereas vascular endothelial growth factor receptor-2 and vascular endothelial growth factor-165 were upregulated.

CONCLUSIONS

Our study revealed that PS-1 might be implicated in the proliferation and invasion of UCB, and that it may serve as a potential therapeutic target for UCB, but further studies are warranted to verify the effects of inhibition of PS/γ-secretase on angiogenesis.

Estrogen receptor β (ERβ) is a novel prognostic marker of recurrence survival in non-muscle-invasive bladder cancer potentially by inhibiting cadherin switch

OBJECTIVE

The function and significance of estrogen receptor β (ERβ) in bladder cancer remains a field of hot debate. In this study, we aimed to (a) evaluate ERβ as a novel prognostic marker of recurrence-free survival and (b) digest the underlying mechanism by elucidating the relationship between ERβ expression and cadherin switch.

METHODS

We examined the expression levels of ERβ, E-cadherin and N-cadherin in 42 initial non-muscle-invasive urothelial bladder carcinomas via immunohistochemistry. Correlation analysis was performed among ERβ expression, cadherin switch, and recurrence-free survival. Moreover, in vitro studies were performed to validate the identified correlation using two bladder cancer cell lines RT4 and 253 J. Upon stimulation with an ERβ-selective agonist diarylpropionitrile, E-cadherin, N-cadherin expressions; cell migration, and invasion capacity were assessed.

RESULTS

Expression of ERβ protein was seen in 34 bladder cancer cases (80.9%), and 21 (50%) specimens showed non-cadherin switch (positive E-cadherin and negative N-cadherin). ERβ expression and the non-cadherin switch are both accompanied with better recurrence-free survival. Also, the least ERβ expression was observed in specimens that undergo cadherin switch. Moreover, these results were consistent with our observations in bladder cancer RT4 and 253 J cell lines studies. Diarylpropionitrile stimulation resulted in an increase in E-cadherin, a decrease in N-cadherin expressions and abolished cell migration and invasion.

CONCLUSION

ERβ is a prognostic marker of recurrence-free rate in non-muscle-invasive bladder cancer, potentially through suppressing cadherin switch, and may act as a potential target for bladder cancer therapy.

Twisted epithelial-to-mesenchymal transition promotes progression of surviving bladder cancer T24 cells with hTERT-dysfunction

Background

Human cancer cells maintain telomeres to protect cells from senescence through telomerase activity (TA) or alternative lengthening of telomeres (ALT) in different cell types. Moreover, cellular senescence can be bypassed by Epithelial-to-mesenchymal transition (EMT) during cancer progression in diverse solid tumors. However, it has not been elucidated the characteristics of telomere maintenance and progression ability after long-term culture in bladder cancer T24 cells with hTERT dysfunction.

Methodology/Principal Findings

In this study, by using a dominant negative mutant human telomerase reverse transcriptase (hTERT) vector to inhibit TA in bladder cancer T24 cells, we observed the appearance of long phenotype of telomere length and the ALT-associated PML body (APB) complex after the 27^th passage, indicating the occurrence of ALT-like pathway in surviving T24/DN868A cells with telomerase inhibition. Meanwhile, telomerase inhibition resulted in significant EMT as shown by change in cellular morphology concomitant with variation of EMT markers. Consistently, the surviving T24/DN868A cells showed increased progression ability in vitro and in vivo. In addition, we found Twist was activated to mediate EMT in surviving T24/DN868A samples.

Conclusions/Significance

Taken together, our findings indicate that bladder cancer T24 cells may undergo the telomerase-to-ALT-like conversion and promote cancer progression at advanced stages through promoting EMT, thus providing novel possible insight into the mechanism of resistance to telomerase inhibitors in cancer treatment.

N-cadherin as a novel prognostic marker of progression in superficial urothelial tumors

PURPOSE

Loss of intercellular adhesion and increased cell motility promote tumor cell invasion and spreading. In bladder cancer, loss or reduced E-cadherin expression has been associated with poor survival, and aberrant expression of N-cadherin has been associated with the invasive phenotype of bladder carcinoma cells. The purpose of this study was to investigate whether N-cadherin expression was associated with the bladder tumor progression.

EXPERIMENTAL DESIGN

E-cadherin and N-cadherin expression was evaluated by immunohistochemistry in 101 tumors (pT1 and pT2-T3) and by reverse transcription-PCR analysis and immunohistochemistry in 28 other fresh frozen tumors (pT(a), pT1, and pT2-T3).

RESULTS

N-cadherin expression was absent in normal urothelium, appeared in stage pT1, and increased in pT2-pT3 tumors. In most cases, increased N-cadherin expression in invasive tumors was associated with loss of E-cadherin expression. Progression-free survival and multivariate analyses revealed that N-cadherin expression is an independent prognostic marker for pT1 tumor progression. Analysis of the 28 frozen tumors by immunohistochemistry and reverse transcription-PCR showed a good correlation between protein and gene expression in pT1 and pT2-T3 tumors. Interestingly, in pT(a) tumors, N-cadherin was not immunodetected, whereas mRNA was present in 50% of cases.

CONCLUSION

Regulatory defects in the N-cadherin promoter, abnormalities at the translational, or protein processing levels could explain the discrepancies between protein and mRNA expression. Most importantly, this study identified N-cadherin as a novel prognostic marker of progression in superficial urothelial tumors. Clearly, N-cadherin acts in an invasive mode in bladder cancer, but whether it has a primary role in urothelial neoplastic progression has yet to be investigated.

Hypoxia attenuates the expression of E-cadherin via up-regulation of SNAIL in ovarian carcinoma cells

Since ovarian carcinoma cells detach from the primary lesion and metastasize via peritoneal dissemination, we hypothesized that these cells are exposed to hypoxia, which may affect cell attachment and invasiveness. To address this hypothesis, we first examined in vivo the immunohistochemical expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and its topological correlation with E-cadherin expression in ovarian carcinomas. We then examined in vitro the effect of hypoxia on the mRNA and protein expressions of E-cadherin using two ovarian cancer cell lines, SKOV3 and OVCAR3, and normal ovarian surface epithelial (OSE) cells. In addition, hypoxia-induced change in the expression of SNAIL, a transcriptional factor repressing E-cadherin expression, was also analyzed. Finally, we examined the facilitation of invasiveness of ovarian cancer cells under hypoxia using Matrigel invasion assay. Immunohistochemically, nuclear localization of HIF-1alpha was observed in 32 of the 76 (42%) carcinomas studied, and showed a topological correlation with loss of E-cadherin expression. Northern blotting, real-time PCR and Western blotting demonstrated that E-cadherin expression was remarkably decreased under hypoxia in both SKOV3 and OVCAR3 cells, but not in normal OSE cells. mRNA expression of SNAIL was increased under hypoxia in both ovarian cancer cell lines. Invasion assay revealed that hypoxia increases the invasiveness of ovarian cancer cells. Accordingly, the present study demonstrated that hypoxia induces down-regulation of E-cadherin in ovarian carcinoma cells, via up-regulation of the transcriptional repressor SNAIL. These findings suggest that hypoxia plays an important role in the change in intercellular attachment, which may be involved in the initiation of tumor progression of ovarian cancer cells.

Different glycosylation of cadherins from human bladder non-malignant and cancer cell lines

BACKGROUND

The aim of the present study was to determine whether stage of invasiveness of bladder cancer cell lines contributes to alterations in glycan pattern of their cadherins.

RESULTS

Human non-malignant epithelial cell of ureter HCV29, v-raf transfected HCV29 line (BC3726) and transitional cell cancers of urine bladder Hu456 and T24 were grown in cell culture. Equal amounts of protein from each cell extracts were separated by SDS-PAGE electrophoresis and were blotted on an Immobilon P membrane. Cadherins were immunodetected using anti-pan cadherin mAb and lectin blotting assays were performed, in parallel. N-oligosaccharides were analysed by specific reaction with Galanthus nivalis agglutinin (GNA), Sambucus nigra agglutinin (SNA), Maackia amurensis agglutinin (MAA), Datura stramonium agglutinin (DSA), Aleuria aurantia agglutinin (AAA), Phaseolus vulgaris agglutinin (PHA-L) and wheat germ agglutinin (WGA). The cadherin from HCV29 cell line possessed bi- and/or 2,4-branched triantennary complex type glycans, some of which were alpha2,6-sialylated. The cadherin from BC3726 cell line exhibited exclusively high mannose type glycans. Cadherins from Hu456 and T24 cell lines expressed high mannose type glycans as well as beta1,6-branched oligosaccharides with poly-N-acetyllactosamine structures and alpha2,3-linked sialic acid residues. Additionally, the presence of fucose and alpha2,6-sialic acid residues on the cadherin from T24 cell line was detected.

CONCLUSIONS

These results indicate that N-glycosylation pattern of cadherin from bladder cancer cell line undergoes modification during carcinogenesis.

Relationship between the expression of E-, N-cadherins and beta-catenin and tumor grade in astrocytomas

Cadherins are cell-surface glycoproteins that mediate Ca2+-dependent, homophilic cell-cell adhesion. The classical cadherins, E- and N-cadherins, connect to beta-catenin, the lining protein. There appears to be a relationship between their dysfunction and tumor invasion and metastasis. The aim of our study was to examine the possibility of a relationship between alterations in the E- and N-cadherin and catenin expression and malignancy in astrocytomas. Forty-five astrocytomas (18 glioblastomas, 16 anaplastic astrocytomas, and 11 diffuse astrocytomas) were collected and stained immunohistochemically for cadherins and beta-catenin. None of the astrocytomas were immunoreactive for E-cadherin. N-cadherin and beta-catenin were present at cell-cell borders in 61% of glioblastomas and 31% of anaplastic astrocytomas. The incidence of immunoreactivity for N-cadherin and beta-catenin increased significantly with the histological grade of astrocytomas (p = 0.001, by Kruskal-Wallis test). Moreover, in anaplastic astrocytomas and glioblastomas, the Ki-67 labeling indices in both N-cadherin-positive and beta-catenin-positive cases were higher than that in negative cases (p = 0.05 and 0.03, respectively, by Fisher's exact test). These results suggest that the expression of N-cadherin or beta-catenin may be related to the biological behavior of astrocytomas.

Tumor suppressor PTEN inhibits nuclear accumulation of beta-catenin and T cell/lymphoid enhancer factor 1-mediated transcriptional activation

beta-Catenin is a protein that plays a role in intercellular adhesion as well as in the regulation of gene expression. The latter role of beta-catenin is associated with its oncogenic properties due to the loss of expression or inactivation of the tumor suppressor adenomatous polyposis coli (APC) or mutations in beta-catenin itself. We now demonstrate that another tumor suppressor, PTEN, is also involved in the regulation of nuclear beta-catenin accumulation and T cell factor (TCF) transcriptional activation in an APC-independent manner. We show that nuclear beta-catenin expression is constitutively elevated in PTEN null cells and this elevated expression is reduced upon reexpression of PTEN. TCF promoter/luciferase reporter assays and gel mobility shift analysis demonstrate that PTEN also suppresses TCF transcriptional activity. Furthermore, the constitutively elevated expression of cyclin D1, a beta-catenin/TCF-regulated gene, is also suppressed upon reexpression of PTEN. Mechanistically, PTEN increases the phosphorylation of beta-catenin and enhances its rate of degradation. We define a pathway that involves mainly integrin-linked kinase and glycogen synthase kinase 3 in the PTEN-dependent regulation of beta-catenin stability, nuclear beta-catenin expression, and transcriptional activity. Our data indicate that beta-catenin/TCF-mediated gene transcription is regulated by PTEN, and this may represent a key mechanism by which PTEN suppresses tumor progression.