ABSTRACT
BACKGROUND: The epithelial cell adhesion molecule (EpCAM) is a type I transmembrane and glycosylated protein, which is overexpressed in many neoplasms. However, EpCAM has no known ligand partners and the mechanisms by which it functions are not fully understood. AIM: This study was performed to discover novel partners of EpCAM, which may provide a better understanding of its functions. METHODS: The membrane fraction of the ERα+ noninvasive breast cancer cell line ZR-75-1 and MCF-7 was extracted and followed by co-immunoprecipitation of EpCAM using C-10, a mouse monoclonal antibody raised against amino acids 24-93 of the EpCAM molecule. As a negative control, MDA-MB-231 and Hs578T were used since they express a negligible amount of EpCAM and are known as EpCAM-/low ERα-/low invasive and tumorigenic breast cancer cell lines. RESULTS: Annexin A2 (ANXA2) was found to be selectively and differentially co-immunoprecipitated with EpCAM in the ERα+ breast cancer cells MCF-7 and ZR-75-1. ANXA2 is a multifunctional protein and known to act as a co-receptor for tissue plasminogen activator (tPA) on the surface of endothelial and cancer cells, thereby affecting fibrinolytic activity and neoangiogenesis as well as invasive and metastatic properties. In this study, the association between EpCAM and ANXA2 was found to affect the activity of tPA. CONCLUSION: This study concludes that ANXA2 co-localizes with EpCAM at the plasma membrane, and the co-localization may have functional implications. Data suggest that EpCAM supports ANXA2 to function as a co-receptor for the tPA, and that EpCAM has a regulatory function on the expression and subcellular localization of ANXA2.
Subject(s)
Annexin A2 , Breast Neoplasms , Animals , Annexin A2/metabolism , Cell Line, Tumor , Epithelial Cell Adhesion Molecule/metabolism , Estrogen Receptor alpha/metabolism , Female , Humans , MCF-7 Cells , Mice , Tissue Plasminogen Activator/metabolismABSTRACT
Both functional ovaries and estrogen replacement therapy (ERT) reduce the risk of type 2 diabetes (T2D). Understanding the mechanisms underlying the antidiabetic effects of 17ß-estradiol (E2) may permit the development of a molecular targeting strategy for the treatment of metabolic disease. This study examines how the promotion of insulin sensitivity and weight loss by E2 treatment in high-fat-diet (HFD)-fed mice involve several anti-adipogenic processes in the visceral adipose tissue. Magnetic resonance imaging (MRI) revealed specific reductions in visceral adipose tissue volume in HFD+E2 mice, compared with HFD mice. This loss of adiposity was associated with diminished visceral adipocyte size and reductions in expression of lipogenic genes, adipokines and of the nuclear receptor nr2c2/tr4. Meanwhile, expression levels of adipose triglyceride lipase/pnpla2 and leptin receptor were increased. As mRNA levels of stat3, a transcription factor involved in brown adipose tissue differentiation, were also increased in visceral adipose, the expression of other brown adipose-specific markers was assessed. Both expression and immunohistochemical staining of ucp-1 were increased, and mRNA levels of dio-2, and of adrß3, a regulator of ucp-1 expression during the thermogenic response, were increased. Furthermore, expression of cpt-1b, a brown adipose-specific gene involved in fatty acid utilization, was also increased. Methylation studies demonstrated that the methylation status of both dio-2 and adrß3 was significantly reduced. These results show that improved glycemic control and weight loss due to E2 involve anti-adipogenic mechanisms which include suppressed lipogenesis and augmented fatty acid utilization, and in addition, the activation of brown adipose tissue-specific gene expression in association with E2-dependent epigenetic modifications in these genes.
Subject(s)
Adipogenesis/drug effects , Adipose Tissue, Brown/metabolism , Biomarkers/metabolism , Estradiol/pharmacology , Gene Expression Regulation/drug effects , Intra-Abdominal Fat/metabolism , Obesity/metabolism , Adipose Tissue, Brown/drug effects , Adipose Tissue, Brown/pathology , Animals , Blotting, Western , DNA Methylation , Diet, High-Fat/adverse effects , Female , Gene Expression Profiling , Insulin Resistance , Intra-Abdominal Fat/cytology , Intra-Abdominal Fat/drug effects , Mice , Mice, Inbred C57BL , Obesity/etiology , Obesity/pathology , Oligonucleotide Array Sequence Analysis , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
A picornavirus (Ljungan virus) has been associated with diabetes in its wild rodent reservoir and in diabetes-prone biobreeding (DP-BB) rats. We attempted to alter the development of diabetes in DP-BB rats using two anti-picornavirus compounds (pleconaril and APO-N039), singly or in combination. Antiviral therapy was initiated 2 weeks before expected onset of diabetes. Pleconaril or APO-N039 alone did not affect the debut of diabetes. However, animals receiving a combination of both compounds were protected for at least the entire period of treatment (4 weeks after expected time of diabetes onset). Immunohistochemistry demonstrated that the presence and distribution of virus antigen in the pancreatic islets coincided with the clinical status of the animal. Data indicate that a treatable picornavirus can be involved in the cellular assault resulting in diabetes and in these cases the disease mechanism appears to involve a virus present in the pancreatic beta cell mass itself.
