HUMAN CHORIONIC GONADOTROPIN-BETA SUBUNIT GENE-EXPRESSION IN CULTUREDHUMAN FETAL AND CANCER-CELLS OF DIFFERENT TYPES AND ORIGINS

Background. The authors' previous investigations using living cultured human cancer cells and cells isolated from cancer tissues, analytical flow cytometry, and monoclonal antibodies directed to epitopes locate d in five different sites of the human chorionic gonadotropin (hCG) mo lecule, identified the presence of membrane-associated hCG, its subuni ts and fragments, by cells from all cancers, irrespective of type and origin, indicating that the expression of these sialoglycoproteins is a common phenotypic characteristic of cancer, Although benign neoplasm s do not express these compounds, cultured human embryonic and fetal c ells also express the same materials, To corroborate these findings, f ive fetal cell lines and 28 cancer cell lines were randomly selected f rom those previously studied, to determine the presence of translatabl e levels of hCG-beta (hCG beta) mRNA. Methods. All cell lines were gro wn under identical conditions, Determination of hCG beta mRNA was made by extracting the total RNA from the cells, followed by synthesis of cDNA with RNase H- reverse transcriptase and polymerase chain reaction amplification using specific hCG beta-luteinizing hormone-beta (hLH b eta) primers. The presence of amplified hCG beta cDNA was corroborated by hybridization of the product with an hCG beta-specific oligonucleo tide and Southern blot analyses of the hybridization products, Gestati onal choriocarcinoma cells and HeLa adenocarcinoma of cervical cells, known producers of biologically active hCG, were positive control subj ects, and human pituitary cells were used as negative control subjects . Results. The results showed single and multiple hCG beta gene activa tion by the fetal cells and the different types of cancer, indicating that at any given time, there is the possibility of activation of as m any as four genes of the six genes of the hCG beta-hLH beta gene clust er, even though alternative gene splicing cannot be ruled out. Conclus ions. In addition to the authors' previous findings, the results of th ese studies support the concept that cancer is a problem of developmen t and differentiation, and, to the authors' knowledge, prove definitiv ely for the first time that synthesis and expression of hCG, its subun its, and its fragments, is a common biochemical denominator of cancer, providing the scientific basis for studies of its prevention and/or c ontrol by active and/or passive immunization against these sialoglycop roteins.