Over‐expression of epidermal growth factor receptor (EGFR) in ovarian cancer has been well documented. Human NIH:OVCAR‐8 ovarian carcinoma cells were transfected with an expression vector containing the anti‐sense orientation of truncated human EGFR cDNA. EGFR anti‐sense over‐expression resulted in decreased EGFR protein and mRNA expression, cell proliferation and tumor formation in nude mice. In accordance with the reduced levels of EGFR in EGFR anti‐sense–expressing cells, tyrosine phosphorylation of EGFR was decreased compared to untransfected parental cells treated with EGF. In EGFR anti‐sense–transfected cells, expression of erbB‐3, but not erbB‐2, was increased. In addition, basal and heregulin‐β1–stimulated tyrosine phosphorylation of erbB‐3 was higher in EGFR anti‐sense vector–transfected cells. A morphological alteration in EGFR anti‐sense gene–expressing cells was correlated with a decrease in the expression of E‐cadherin, α‐catenin and, to a lesser extent, β‐catenin. Changes in the expression of these proteins were associated with a reduction in complex formation among E‐cadherin, β‐catenin and α‐catenin and between β‐catenin and EGFR in EGFR anti‐sense–expressing cells compared to sense‐transfected control cells. These results demonstrate that EGFR expression in ovarian carcinoma cells regulates expression of cell adhesion proteins that may enhance cell growth and invasiveness. Int. J. Cancer 88:566–574, 2000. © 2000 Wiley‐Liss, Inc.

We previously demonstrated that antibodies against myelin basic protein (MBP) obtained from animals with experimental allergic encephalomyelitis (EAE), induced with MBP and purified by affinity chromatography, have the property to recognize a neuronal protein, synapsin Ia and Ib. To investigate whether this crossreactivity also occurs at the cellular level, we purified spleen and lymph node mononuclear cells from rats sensitized with MBP or synapsin using polystyrene plates coated with the respective antigen. We observed that animals injected with MBP have T lymphocytes that bind both antigens. Using the same system, each purified cell population was confronted again to the studied antigens. The anti-MBP cells recognized once more epitopes of MBP and about 40% of them also recognized synapsin. On the other hand, cells that first were attached to synapsin, in the second exposure to antigens bound to MBP and synapsin in similar amounts. Double immunofluorescent labeling of the mononuclear cells isolated from animals injected with bovine myelin or MBP showed that the same lymphocyte was able to recognize MBP as well as synapsin. In both experimental systems the quantitative results were similar indicating that in bovine myelin- or MBP-sensitized animals practically all the cells that recognize synapsin are anti-MBP cells, and of the total cells raised against MBP, around 40% of them show this crossreactivity. On the contrary, animals injected with synapsin have cells that bind to this protein but not to MBP indicating that the described crossreactivity, as observed at humoral level, is only in one way.(ABSTRACT TRUNCATED AT 250 WORDS)

Cripto-1 (CR-1) is an epidermal growth factor (EGF)-related protein. CR-1 can inhibit b-casein and whey acidic protein expression in mouse mammary epithelial cells. The present study demonstrates that CR-1 can induce apoptosis in HC-11 mouse mammary epithelial cells, as measured by bisbenzimide stained nuclei, TUNEL assay and cell death ELISA. Apoptosis could be observed after 2 days of exposure of confluent HC-11 cells to CR-1 in the absence of the survival factors EGF and insulin, with maximum apoptosis occurring at 3 days. A reduction in poly(ADP-ribose) polymerase (PARP) expression and an increase in b-catenin cleavage was found after 18 h of exposure to CR-1 suggesting that apoptosis was preceded by the induction of a caspase activity since the caspase inhibitor ZFAD.FMK could block the CR-1-induced reduction in PARP expression and CR-1-induced apoptosis. CR-1 was found to increase the expression of caspase-3-like protease. Although, the levels of p27 kip1 and p21Bax did not change after exposure to CR-1 for 18 h, the levels of Bcl-x L became undetectable. These studies suggest that CR-1 promotes apoptosis by mediating the induction of caspase-3-like protease and downregulating the expression of Bcl-x L .