The HuT series of 'carcinogen-transformed' human fibroblast cell lines are derived from the human fibrosarcoma cell line 8387

In 1977 Kakunaga reported the carcinogen-induced transformationof the diploid human fibroblast cell line KD into focus-forming,morphologically altered cells. Cell lines were developed from15 individual foci. These exhibited an infinite lifespan inculture and all those that were tested (7/7) formed malignanttumors(sarcomas) in athymic mice. The existing cell lines, designatedHuT-11 to HuT-14, have been studied intensively during the pastdecade as examples of human fibroblasts malignantly transformedby treatment with a chemical carcinogen, 4-nitroquinoline-1-oxide.Recently, in comparing the HuT-1, HuT-12 and HuT-14 cell lineswith KD cells, McCormick and Maher (Mutat. Res., 199, 273–291,1988) found evidence that the malignant cells could not havebeen derived from the latter. But, this did not rule out thepossibility that as the target cells for his original studyof carcinogen-induced transformation, Kakunaga had inadvertentlyused cells from some other, unidentified normal individual.Since the donor of such cells would not be known and the originalcell line was not available, it would be impossible to determinethe degree of identity between such a target cell line and theHuT cell lines. However, in the course of examining methodsfor such testing, we recently became aware that the isozymepattern of these HuT cell lines was identical to that of thehuman fibrosarcoma-derived cell line 8387 established in 1966.We here report that the HuT cell lines and the 8387 cell linealso exhibit an identical series of HLA determinants and identicalrestriction fragment length polymorphisms(RFLPs). Assuming thateach of these three assays measures independently inheritedcharacteristics, the chance that an unrelated donor of the fibroblaststhat gave rise to the HuT cell lines happened to possess characteristicsidentical to those of the patient whose fibrosarcoma gave riseto the 8387 cell line is 1 x 10^–8. Therefore, we concludethat 8387 cells are the source of the malignant cells designatedHuT from Kakunaga's original transformation experiment. AdditionalRFLP analysis, using a probe made from M13 bacteriophage DNAwhich detects a hyperpolymorphic ‘minisatellite’pattern in human DNA, also showed that DNA from HuT-14 cellsand from 8387 cells exhibit identical banding patterns, indicatingthat the cell lines were taken from the same individual.Thelatter banding patterns differed from that observed with DNAfrom KD cells. Karyotyping studies showed that HuT-12 and HuT-14cells have six marker chromosomes and that these are identicalto the six marker chromosomes seen in the 8387 cells. The resultsemphasize the necessity of validating in vitro transformationexperiments by showing that the parental cells and the malignantcells have a common origin.