Differential expression of apoptotic genes in gestational trophoblastic diseases

DUMUR C.I.; ALMENARA J.A.; DURAND E.S.; FLURY A.; PATRITO L.C.

Buenos Aires

Simposio; Common Themes in Transcription and RNA Processing; 1999

International Centre for Genetic Engineering and Biotechnology (Italy), Agencia Nacional de Promoción de Ciencia y Tecnología, Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular, y Universidad de Buenos Aires (Argentina)

Gestational trophoblastic diseases comprise a group of interrelated neoplasms, including complete hydatidiform mole (CHM), persistent gestational trophoblastic tumor (GTT), and choriocarcinoma. To better define the molecular features of these diseases, a CHM cDNA library was constructed and a novel cDNA sequence, named CHMS-l, was isolated by differential screening. This transcript is highly expressed in CHM in comparison with both normal early and term placenta but undetectable in CHM derived persistent GTT and in the human choriocarcinoma derived JEG-3 cells. The CHMS-l sequence share a 62% homology with the tumor necrosis factor receptor 2 cDNA and its amino acid deduced sequence shared a high level of homology with the "death domain" region found in two members of the TNF-Rs superfamily, TNF-R1 and Fas. The presence of a potential "death domain" in CHMS-1 together with its high expression level in CHM, strongIy suggests that the CHMS-l gene encodes a protein that might be involved in tumor regression processes, through an apoptotic mechanism. In order to define the potential role of CHMS-1 in transducing apoptotic signals, its death domain was fused to the green fluorescent protein (GFP). Transient expression of CHMS-1-GFP fusion protein in the COS-7 cell line causes morphological changes associated to apoptosis. This cell death process is accurately regulated by several master proteins such as the transcription factor p53 that regulates the Bcl-2 family, and death receptors that transduce external signals. In that way we also analyze the Bcl-2 protein expression profile in gestational trophoblastic diseases by immunohistochemistry. BcI-2 immunostaining was most prominent in the highly invasive tissues such as normal early placenta and persistent GTT. It was also found in CHM, whereas staining was weak. These staining patterns inversely correlate with the p53 mRNA expression. This transcript was largely expressed in CHM as revealed Northern blotting analysis. CollectiveIy, these results may explain the normal molar tissue regression occurring at later stages of molar development by an apoptotic way. This work was supported by grants from CONICET, FONCYf and SECyT.