Production of human-mouse somatic cell hybrids and characterization for carcinoembryonic antigen expression

Abstract

Carcinoembryonic antigen (CEA), a human tumor-associated marker for many epithelial tumors, has been well characterized immunologically and structurally but its biological function(s) remains a mystery. The objectives of this investigation were to produce interspecific somatic cell hybrids between human colorectal, CEA expressing/secreting, cancer cell lines (LS174T, SKC01 and HT29) and mouse cell lines (NS1 SP2/0, RAG, PG19 and STO) and to characterize the resultant hybrids for CEA expression/secretion with the longer term goal of assigning the CEA gene(s) to a particular chromosome. -- Fusions were performed using a polyethylene glycol (PEG) suspension technique and hybrids were isolated by hypoxanthine-aminopterin-thymidine/ouabain double selection and characterized for CEA expression/secretion in specific CEA immunoassays. Forty-eight fusions were performed (43, monolayer-suspension; 5, monolayer-monolayer) producing 344 hybrid colonies of the following types (SKCO1xRAG, SKCO1xSTO, HT29xRAG, HT29xSTO and HT29xNS1). Chromosomal analysis by Giemsa differential staining confirmed that these fusion products were definite hybrids containing human and mouse chromosomes.--- This study has demonstrated (1) the successful production of human-mouse somatic cell hybrids, (2) that fusion of monolayer-monolayer cell lines resulted in a greater yield of hybrids and (3) that none of the hybrids obtained showed high levels of CEA expression/secretion, probably because the RAG and STO cell lines were nonpermissive fusion partners.