Adriamycin activates E-cadherin-mediated cell-cell adhesion in human breast cancer cells

The E-Cadherin and N-Cadherin Switch in Epithelial-to-Mesenchymal Transition: Signaling, Therapeutic Implications, and Challenges

Epithelial-to-Mesenchymal Transition (EMT) has been shown to be crucial in tumorigenesis where the EMT program enhances metastasis, chemoresistance and tumor stemness. Due to its emerging role as a pivotal driver of tumorigenesis, targeting EMT is of great therapeutic interest in counteracting metastasis and chemoresistance in cancer patients. The hallmark of EMT is the upregulation of N-cadherin followed by the downregulation of E-cadherin, and this process is regulated by a complex network of signaling pathways and transcription factors. In this review, we summarized the recent understanding of the roles of E- and N-cadherins in cancer invasion and metastasis as well as the crosstalk with other signaling pathways involved in EMT. We also highlighted a few natural compounds with potential anti-EMT property and outlined the future directions in the development of novel intervention in human cancer treatments. We have reviewed 287 published papers related to this topic and identified some of the challenges faced in translating the discovery work from bench to bedside.

Adriamycin-Induced Models of VACTERL Association

Animal models are of great importance for medical research. They have enabled analysis of the aetiology and pathogenesis of complex congenital malformations and have also led to major advances in the surgical and therapeutic management of these conditions. Animal models allow us to comprehend the morphological and molecular basis of disease and consequently to discover novel approaches for both surgical and medical therapy. The anthracycline antibiotic adriamycin was incidentally found to have teratogenic effects on rats, producing a range of defects remarkably similar to the VACTERL association of congenital anomalies in humans, providing a reproducible animal model of this condition. VACTERL association is a spectrum of birth defects which includes vertebral, anal, cardiovascular, tracheo-oesophageal, renal and limb anomalies. In recent years, adriamycin rodent models of VACTERL have provided valuable insights into the pathogenesis of this complex association, particularly in relation to tracheo-oesophageal malformations. The adriamycin rat model and adriamycin mouse model are now well established in the investigation of the morphology of faulty organogenesis and the regulation of gene expression in tracheo-oesophageal anomalies.

Anti-apoptotic effect of claudin-1 on TNF-α-induced apoptosis in human breast cancer MCF-7 cells

Accumulating evidence reveals that aberrant expression of claudins manifests in various tumors; however, their biological functions are poorly understood. Here, we report on the elevated expression of claudin-1 in human breast cancer MCF-7 cells under tumor necrosis factor (TNF)-α treatment. Interestingly, the increased expression of claudin-1 contributes to an anti-apoptotic role in TNF-α-induced apoptosis. In line with this, upon TNF-α stimulus, downregulation of claudin-1 by siRNA knockdown results in a significant increase in cleavage of caspase-8 and poly (ADP-ribose) polymerase, a decrease of cyclinD1 expression, and DNA fragmentation. Consistently, TdT-mediated dUTP nick end labeling assay also shows that loss of claudin-1 increases the susceptibility of MCF-7 cells to TNF-α-induced apoptosis. However, there is no obvious effect on the expression of Bax and p53 after the treatment aforementioned. In addition, TNF-α increases the amount of claudin-1 and the cytoplasmic accumulation of β-catenin, while claudin-1 siRNA increases the amount of β-catenin in the cell membrane as well as the amount of E-cadherin in the cytoplasm. In conclusion, our data reveal a novel role of claudin-1 in regulating apoptosis in MCF-7 cells.

Screening of drugs to counteract human papillomavirus 16 E6 repression of E-cadherin expression

Persistent infections with certain high-risk human papillomavirus (HPV) types such as 16 and 18 can result in the development of cervical cancer. Neither of the two prophylactic vaccines against HPV16 and 18 that are in current use have any therapeutic efficacy for prevalent HPV infections. Ablative therapy is widely used for the treatment of HPV cervical dysplasia however disease recurrence is a widely recognized problem. Thus there is a continuing need for therapeutic approaches for the treatment of HPV infections. The HPV16 E6 viral oncoprotein represses surface expression of the cellular adhesion molecule, E-cadherin. Reduced E-cadherin expression on HPV-infected keratinocytes is associated with lowered numbers of antigen-presenting Langerhans cells in the infected epidermis, potentially reducing immune surveillance for HPV. Four chemicals reported to up-regulate E-cadherin were screened for their ability to counteract E6 repression of surface E-cadherin. 5-Aza-2'-deoxycytidine (AzaDC), a DNA methyltransferase inhibitor, and Indole-3-carbinol (I3C), reported to increase E-cadherin through a p21(Waf1/Cip1)-dependent mechanism, had low cytotoxicity and increased or restored E-cadherin expression and adhesive function in HPV16 E6 expressing HCT116 cells. Doxorubicin, also known to induce p21(Waf1/Cip1), increased E-cadherin in E6 expressing cells but had some associated cytotoxicity. Tamoxifen, which can restore adhesive function of surface E-cadherin, was ineffective in counteracting E6 repression of E-cadherin. AzaDC and I3C both show potential to restore antigen-presenting cells to HPV infected skin by antagonizing E6 repression of E-cadherin, thereby counteracting an important immune evasion mechanism of HPV16 and reinstating immune function at the infected site.

Anti-apoptotic effect of claudin-1 in tamoxifen-treated human breast cancer MCF-7 cells

Background

Claudin-1 is a membrane protein of tight junctions, and is associated with the development of various cancers. However, the significance of claudin-1 expression in cancer cells is not well understood. Here, we showed for the first time the anti-apoptotic effect of claudin-1 in human breast cancer MCF-7 cells.

Methods

Human breast cancer MCF-7 and T47 D cells were treated with or without tamoxifen, siRNA against claudin-1, or tamoxifen and claudin-1 siRNA. The samples were analyzed by RT-PCR, Western blotting or immunofluorescent staining.

Results

The expression of claudin-1 was upregulated in tamoxifen-treated MCF-7 cells, whereas the expression of claudin-1 was not altered in tamoxifen-treated T47 D cells. Knockdown of claudin-1 by siRNA increased the amount of poly (ADP-ribose) polymerase (PARP) regardless of tamoxifen treatment in MCF-7 cells, but not T47 D cells. In the cell membranes of the MCF-7 cells, tamoxifen treatment increased the amount of claudin-1, but decreased the amount of β-catenin. Claudin-1 siRNA increased the amount of E-cadherin in the cytoplasm of the MCF-7 cells as well as the amount of β-catenin in their cell membranes.

Conclusion

These results indicate that claudin-1 has anti-apoptotic effects, and is involved in the regulation of the expression and subcellular localization of β-catenin and E-cadherin in MCF-7, but not T47 D cells.

Multiparametric monitoring of tumor response to chemotherapy by noninvasive imaging

With the emerging concept of individualized cancer therapy, it becomes crucial to develop methods for the noninvasive assessment of treatment outcome. With this in mind, we designed a novel approach for the comprehensive evaluation of response to chemotherapy with the established agent doxorubicin in a preclinical breast cancer model. This approach delivers information not only about change in tumor size but also about target antigen expression. Our strategy relies on a tumor-specific contrast agent (MN-EPPT) targeting the underglycosylated MUC-1 (uMUC-1) tumor antigen, found on more than 90% of breast cancers and predictive of chemotherapeutic response. MN-EPPT consists of superparamagnetic iron oxide nanoparticles (MN) for magnetic resonance imaging, modified with Cy5.5 dye (for near-IR fluorescence optical imaging), and conjugated to peptides (EPPT), specifically recognizing uMUC-1. In vivo, treatment of mice bearing orthotopic human breast carcinomas with doxorubicin led to a reduction in tumor mass and resulted in down-regulation of uMUC-1. The tumor-specific accumulation of MN-EPPT allowed the assessment of change in tumor volume by noninvasive imaging. Furthermore, in mice injected with MN-EPPT, tumor delta-T2 was significantly reduced after treatment with doxorubicin, indicating a lower accumulation of MN-EPPT and reflecting the reduced expression of uMUC-1. With these studies, we have shown the utility of magnetic resonance imaging for the multiparametric characterization of breast tumor response to chemotherapy. This approach has the potential of significantly advancing our ability to better direct the development of molecularly targeted individualized therapy protocols because it permits the monitoring of therapy on a molecular scale.

Role of cell adhesion signal molecules in hepatocellular carcinoma cell apoptosis

AIM: Cell adhesion molecules and their signal molecules play a very important role in carcinogenesis. The aim of this study is to elucidate the role of these molecules and the signal molecules of integrins and E-cadherins, such as (focal adhesion kinase) FAK, (integrin linked kinase) ILK, and β-catenin in hepatocellular carcinoma cell apoptosis.

METHODS: We first synthesized the small molecular compound, S-(1,2-dichlorovinyl)-L-cysteine (DCVC), and identified it, by element analysis and ¹H NMR. To establish the apoptosis model of the SMMC-7721 hepatocellular carcinoma cell, we treated cells with DCVC in EBSS for different concentrations or for various length times in the presence of 20 μmol/L N,N’-diphenyl-p-phenylenediamine, which blocks necrotic cell death and identified this model by flow cytometry and DNA ladder. Then we studied the changes of FAK, ILK, β-catenin, and PKB in this apoptotic model by Western blot.

RESULTS: We found that the loss or decrease of cell adhesion signal molecules is an important reason in apoptosis of SMMC-7721 hepatocellular carcinoma cell and the apoptosis of SMMC-7721 cell was preceded by the loss or decrease of FAK, ILK, PKB, and β-catenin or the damage of cell-matrix and cell-cell adhesion.

CONCLUSION: Our results suggested that the decrease of adhesion signal molecules, FAK, ILK, PKB, and β-catenin, could induce hepatocellular carcinoma cell apoptosis.

A pituitary gene encodes a protein that produces differentiation of breast and prostate cancer cells

A cDNA clone of 1.1 kb encoding a 108-aa polypeptide was isolated from a human pituitary cDNA library by expression cloning. This protein was named tumor differentiation factor (TDF). The recombinant TDF protein and a 20-aa peptide, P1, selected from the ORF of the gene, induced morphological and biochemical changes consistent with differentiation of human breast and prostate cancer cells. Fibroblast, kidney, hepatoma, and leukemic lymphocytic cell lines were unaffected. Breast and prostate cancer cells aggregated in spheroid-like structures within 24 h of exposure to TDF. This effect was abrogated by a specific affinity-purified rabbit polyclonal anti-P1 Ab. E-cadherin expression was increased in a dose-dependent manner by TDF. Treatment of MCF7 cells with TDF led to production of a lactalbumin-related protein. Peptide P1 significantly decreased the growth of androgen-independent DU145 prostate cancer in severe combined immunodeficient mice. The presence of TDF protein in human sera was detected by the anti-P1 Ab, suggesting a role of TDF in endocrine metabolism. The fact that all activities of TDF can be mimicked by a peptide derived from the encoding TDF sequence opens the possibility of therapeutic applications.

Cadherin junctions in mammary tumors

Cadherins are the transmembrane component of adherens junctions found between interacting cells in tissues. The cadherins bind cells to one another in a specific manner and link to the actin cytoskeleton through intracellular catenins. In addition to promoting strong cell-cell adhesion, cadherins appear to initiate and modify intracellular signaling pathways. The loss of E-cadherin function in epithelial cells is thought to be an important step in tumorigenesis. Moreover, anomalous expression of inappropriate cadherins in epithelial cells alters their behavior and may contribute to the tumorigenic phenotype. For breast cancer the decreased expression of E-cadherin alone may have limited value as a prognostic indicator; however, examining the repertoire of cadherins and catenins expressed by tumors may provide useful prognostic information.