In vitro derived mouse A9 cell clones differing in malignancy: analysis by somatic cell hybridization with YACIR lymphoma cell clones.

Abstract

A culture of mouse A9 cells yielded clones of both high and low malignancy. Confirmation of the differences in malignancy of the clones was obtained after their hybridization with subclones of YACIR, a lymphoma induced by Moloney leukemia virus. Low malignant A9 clones suppressed the malignancy of the YACIR partner in the hybrids. Hybrids between a highly malignant A9 clone and two different clones of YACIR "complemented" to yield hybrids of reduced malignancy.No correlation was found between the malignancy of a particular A9 clone and its ability to produce a focus-forming mouse C-type virus.A9, a variant of mouse L cells deficient in hypoxanthine/guanine phosphoribosyltransferase (HGPRT) (1), has been used extensively as a parental cell in the analysis of malignancy by somatic cell hybridization (2, 3). The standard A9 subline used is of low malignancy and has been fused with a variety of highly malignant murine tumors. Such hybrids are of low malignancy when inoculated into x-irradiated syngeneic newborn mice so long as the hybrid retains all or nearly all the chromosomes of both parental cells. These data are consistent with the presence in the low malignant cells of genetic information whose expression is incompatible with tumor formation. If such information is lost, or its expression is blocked, a highly malignant subline can develop.Fluctuation in the take incidence of L cells passaged in culture over many years has been reported (4), but conclusive evidence for the simultaneous presence of cells of both high and low malignancy within a single cultured cell line has not previously been documented. Highly malignant variants of L cells (4) and of A9 (A9HT) (5) (7,8).Somatic Cell Hybridization. Beta propiolactone-inactivated Sendai virus was used to fuse the cells essentially as described (9). The hybrid cells originated as single colonies, one colony only being taken from a particular bottle.Cell Cloning. A9 cells were cloned either by suspension in 0.3% agarose-containing medium at a density of 10 cells per ml (10) or in liquid culture in petri dishes with an initial inoculum of five cells per 60 mm petri dish. One clone only was subsequently picked from each dish.Chromosome Preparation. Metaphase spreads were prepared essentially as described (11) and stained with Giemsa.Test for Malignancy. Viable cells (1 X 105) were inoculated to x-irradiated (4 J/kg) syngeneic newborn mice. Mice were scored for tumor formation (a "take") during the 3 subsequent months, after which the experiment was terminated. Animals not developing tumors by this time were scored as negative. with phosphate-buffered saline and infected with 0.5 ml volumes of virus dilutions. The virus source was cell culture supernatant that had been passed through a Millipore filter of 0.45 ,m pore size. The virus was allowed to adsorb to the cells for 60 min at 370 and then the cultures were rinsed with medium. The medium was changed every third day. The cultures were observed at days 7, 10, and 17 for morphologically altered foci accordi...

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“…5). Figure 5 shows a typical record from an A9 cell (Clements et al 1976) perfused with a large‐diameter pipette tip. The solutions employed in Fig.…”

An abnormal membrane glycoprotein associated with malignancy in a wide range of different tumours

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Adaptive Evolution of Mus Apobec3 Includes Retroviral Insertion and Positive Selection at Two Clusters of Residues Flanking the Substrate Groove

“…A sample of M. m. macedonicus DNA was provided by R. Elliott (Roswell Park, Buffalo). Cell lines used as DNA and RNA sources included NZB-Q and M. fragilicauda cells obtained from J. Hartley (NIAID, Bethesda, MD), cells from some wild mouse species obtained from J. Rodgers (Baylor College of Medicine, Houston, TX), and NIH 3T3, M. dunni [48] , SC-1 [49] , A9 (C3H/He) [50] , and CMT93 (C57BL) (ATCC CCL-223).…”