Micro-encapsulation of MDCK-ras-e cells prevents loss of E-cadherin invasion-suppressor function in vivo

Microencapsulation for the Therapeutic Delivery of Drugs, Live Mammalian and Bacterial Cells, and Other Biopharmaceutics: Current Status and Future Directions

Microencapsulation is a technology that has shown significant promise in biotherapeutics, and other applications. It has been proven useful in the immobilization of drugs, live mammalian and bacterial cells and other cells, and other biopharmaceutics molecules, as it can provide material structuration, protection of the enclosed product, and controlled release of the encapsulated contents, all of which can ensure efficient and safe therapeutic effects. This paper is a comprehensive review of microencapsulation and its latest developments in the field. It provides a comprehensive overview of the technology and primary goals of microencapsulation and discusses various processes and techniques involved in microencapsulation including physical, chemical, physicochemical, and other methods involved. It also summarizes the state-of-the-art successes of microencapsulation, specifically with regard to the encapsulation of microorganisms, mammalian cells, drugs, and other biopharmaceutics in various diseases. The limitations and future directions of microencapsulation technologies are also discussed.

Differential regulation of cadherin expression by osteotropic hormones and growth factors in vitro in human osteoprogenitor cells

AIM

To examine if cadherins are expressed constitutively in human bone marrow stromal cells (hBMSC) and investigate the regulation of cadherin expression by various osteotropic hormones and local factors.

METHODS

Cadherin expression was examined in first passaged (secondary) hBMSC as well as in the conditionally-immortalized human osteoprogenitor cell line (hOP-7). Using a monoclonal antibody (MoAb C-1821) to a cytoplasmic domain common to all known cadherins (pan-cadherin MoAb), cadherins were immunolocalized in first passaged hBMSC as well as in hOP-7 cells. In addition, intense immunostaining for cadherin expression was associated with alkaline phosphatase (ALP) in nodules formed in the high density cultures of hOP-7 cells. Human E-cadherin (HECD) was specifically detected by Western blotting in extracts of untreated hBMSC using an anti-HECD MoAb 004FD.

RESULTS

Differential regulation of cadherin expression by various osteotropic hormones and local factors (parathyroid hormone, dexamethasone, estradiol, prostaglandin E2, basic fibroblast growth factor, and tumor necrosis factor-beta) was also observed. In addition, blocking cadherins with the MoAb C-1821 increased basal ALP activity and had an additive effect on 1, 25(OH) 2D3-induced ALP activity.

CONCLUSION

Cadherins are expressed in human osteoprogenitor cells and are involved in the osteogenic differentiation. The differential modulation of cadherin expression by osteotropic agents indicates that these agents may regulate osteoprogenitor cells through different cadherins and these cadherins may play different roles.

Biological relevance of E-cadherin-catenin complex proteins in primary epithelial ovarian tumours

This study analysed the biological relevance of E-cadherin, alpha-catenin, beta-catenin and gamma-catenin immunoexpression pattern (reduced vs. preserved phenotype) in epithelial ovarian tumours. Immunohistochemistry was used to evaluate the expression of these proteins in 154 epithelial ovarian tumours, consisting of 17 benign, 33 borderline and 104 malignant tumours. In borderline tumours, the immunoexpression pattern of E-cadherin (p = 0.014) and alpha-catenin (p = 0.030) associated with histological type. In malignant tumours, the immunoexpression pattern of E-cadherin was related with histological type (p = 0.001). The immunoexpression pattern of beta-catenin associated with histological type and tumour differentiation (p = 0.005, p = 0.025, respectively). The preserved phenotype of E-cadherin was most frequently observed in mucinous tumours, whereas reduced E-cadherin was most frequently observed in serous tumours. The preserved phenotype of beta-catenin associated with endometrioid carcinomas, while reduced beta-catenin associated with poorly differentiated serous and clear cell carcinomas. Although the reduced phenotype was the most frequent immunoexpression observed for all proteins of the E-cadherin-catenin complex in epithelial ovarian tumours, only beta-catenin showed a significant difference between benign, borderline and malignant tumours (p = 0.045), since borderline and malignant tumours most frequently showed the reduced phenotype. The immunohistochemical profile of beta-catenin was shown to be of biological relevance: reduced beta-catenin was correlated with loss of tumour differentiation and serous carcinomas that are known to depict aggressive biological behaviour in epithelial ovarian tumours.

Association of E-cadherin and β-catenin immunoexpression with clinicopathologic features in primary ovarian carcinomas

Epithelial cadherin forms a complex with alpha-, beta-, and gamma-catenin proteins. Reduced expression of E-cadherin-catenins has been shown in human carcinomas and is associated with low histologic differentiation, increased risk of invasion, and metastatic disease. The immunoexpression pattern of E-cadherin and beta-catenin (reduced versus preserved phenotype) was evaluated in 104 primary ovarian carcinomas and related to clinicopathologic features of the tumors. The immunoexpression pattern of E-cadherin was associated with International Federation of Gynaecology and Obstetrics (FIGO) staging (P = 0.043), histologic subtype (P = 0.001), peritoneal metastasis (P = 0.006), and residual tumor (P = 0.036). The reduced phenotype of E-cadherin that was observed in 64% of the carcinomas (67/104) was associated with advanced stage tumors, serous carcinomas, presence of peritoneal metastasis, and residual tumor larger than 2 cm. The immunoexpression pattern of beta-catenin was associated with histologic subtype (P = 0.005), tumor differentiation (P = 0.025), and peritoneal metastasis (P = 0.041). The reduced phenotype of beta-catenin that was observed in 74% of the carcinomas (77/104) was associated with advanced stage tumors, poorly differentiated serous and clear cell carcinomas, presence of peritoneal metastasis, and residual tumor. The immunoexpression pattern of E-cadherin was correlated with beta-catenin (P = 0.001). The reduced phenotype for both E-cadherin and beta-catenin was associated with histologic subtype (P < 0.001) and peritoneal metastasis (P = 0.001). In conclusion, the immunohistochemical profile of E-cadherin and beta-catenin may be useful in identifying a particular subpopulation of ovarian cancer patients who are characterized by an adverse clinical outcome, because the reduced phenotype of these molecules was associated with poor tumor differentiation, peritoneal metastasis, and advanced FIGO stage tumors.

Loss of E-cadherin expression in melanoma cells involves up-regulation of the transcriptional repressor Snail

Malignant transformation of melanocytes frequently coincides with loss of E-cadherin expression. Here we show that loss of E-cadherin in melanoma cell lines does not involve mutations in the E-cadherin gene, promoter methylation, or alterations in expression of AP-2 transcription factors as suggested previously. In a panel of different melanoma cell lines, E-cadherin expression was negatively regulated by up-regulation of the transcription factor Snail. In comparison with primary human melanocytes, where Snail expression was not detected by reverse transcription-polymerase chain reaction, significant expression was found in all eight melanoma cell lines. In parallel, Western blot and reverse transcription-polymerase chain reaction analysis revealed strong reduction of E-cadherin expression in the melanoma cells. Consistently, transient transfection of a Snail expression plasmid into human primary melanocytes led to significant down-regulation of E-cadherin, whereas transient and stable transfection of an antisense Snail construct induced reexpression of E-cadherin in Mel Ju and Mel Im melanomas. In summary, we conclude that activation of Snail expression plays an important role in down-regulation of E-cadherin and tumorigenesis of malignant melanomas.

Methylation patterns of the E-cadherin 5' CpG island are unstable and reflect the dynamic, heterogeneous loss of E-cadherin expression during metastatic progression

Metastatic progression of most common epithelial tumors involves a heterogeneous, transient loss of expression of the homotypic cell adhesion protein, E-cadherin, rather than the uniform loss of a functional protein resulting from coding region mutation. Indeed, whereas E-cadherin loss may promote invasion, reexpression may facilitate cell survival within metastatic deposits. The mechanisms underlying such plasticity are unclear. We now show that the heterogeneous loss of E-cadherin expression in primary human breast cancers reflects a heterogeneous pattern of promoter region methylation, which begins early prior to invasion. In cultured human tumor cells, such heterogeneous methylation is dynamic, varying from allele to allele and shifting in relation to the tumor microenvironment. Following invasion in vitro, which favors diminished E-cadherin expression, the density of promoter methylation markedly increased. When these cells were cultured as spheroids, which requires homotypic cell adhesion, promoter methylation decreased dramatically, and E-cadherin was reexpressed. These data show that the methylation associated with E-cadherin loss in human breast cancer is heterogeneous and unstable and suggest that such epigenetic plasticity may contribute to the dynamic, phenotypic heterogeneity that drives metastatic progression.

Inhibition of adhesion and induction of epithelial cell invasion by HAV-containing E-cadherin-specific peptides

The E-cadherin/catenin complex, an organizer of epithelial structure and function, is disturbed in invasive cancer. The HAV (histidine alanine valine) sequence in the first extracellular domain of E-cadherin is crucial for homophilic interactions between cadherins. We report that specific peptides containing an HAV sequence interfere with the functions of the E-cadherin/catenin complex. Cells either expressing specific cadherins or not were challenged with both cadherin and noncadherin peptides comprising a central HAV sequence. Specific E-cadherin peptides inhibited cell aggregation, disturbed the epithelial morphotype and were able to stimulate invasion of cells expressing E-cadherins. Conditioned medium, containing E-cadherin fragments, also stimulated invasion in contrast to conditioned medium from which the E-cadherin fragments were removed. Our studies show that E-cadherin functions are inhibited by homologous proteolytic HAV-containing fragments that are released in an autocrine manner and subsequently inhibit the E-cadherin/catenin complex. In this way such cadherin fragments may induce and support cancer invasion.

E-cadherin and its associated protein catenins, cancer invasion and metastasis

E-cadherin is a cell-cell adhesion molecule which is anchored to the cytoskeleton via catenins. There is increasing evidence which suggests that E-cadherin also acts as a suppressor of tumour invasion and metastasis. Both in vitro and in vivo studies have revealed that expression of E-cadherin correlates inversely with the motile and invasive behaviour of a tumour cell; it also correlates inversely with metastasis in patients with cancer. The function of E-cadherin is highly dependent on the functional activity of catenins. This review summarizes progress, from both basic and clinical research, in our understanding of the roles of E-cadherin and catenins, and discusses the clinical relevance of the discoveries.