Efficient one-step selection of hepatoma cell variants of a variety of phenotypes by use of aflatoxin B1

Corcos, Laurent; Weiss, Mary C.

doi:10.1111/j.1432-0436.1988.tb00207.x

Cited by 4 publications

(3 citation statements)

References 25 publications

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“…Morphologically heterogeneous dedifferentiated variants isolated from populations of differentiated hepatoma cells (23,59) spontaneously display this dissociation, which we refer to as an uncoupled phenotype. We have analyzed cells of the uncoupled phenotype with the following two aims in mind: (i) to determine whether the phenotype is intermediate between the differentiated and the dedifferentiated states of hepatoma cells and (ii) to understand why genes coding for hepatic functions fail to be expressed even though the LETF, and in particular HNF4 and HNF1, are present.…”

Section: Discussionmentioning

confidence: 97%

“…One approach to the identification of such new activators or silencers of hepatic differentiation consists of a phenotypic characterization of cells of common origin that do and do not display a dissociation between expression of the LETF and their target functions. In the extensively characterized rat hepatoma H4IIEC3 cell system, appropriate cell lines to search for such a dissociation turned out to be morphologically heterogeneous variants, previously designated as unstable (11,23,59). Moore and Weiss (59) demonstrated that certain of these clonal variants selected from differentiated hepatoma cells can give rise to both dedifferentiated and differentiated progeny clones.…”

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confidence: 99%

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Liver-Enriched Transcription Factors Uncoupled from Expression of Hepatic Functions in Hepatoma Cell Lines

Chaya

Fougère-Deschatrette

Weiss

1997

Molecular and Cellular Biology

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Among the liver-enriched transcription factors identified to date, only expression of hepatocyte nuclear factor 4 (HNF4) and hepatocyte nuclear factor 1 (HNF1) is in strict correlation with hepatic differentiation in cultured rat hepatoma cells. Indeed, differentiated hepatoma cells that stably express an extensive set of adult hepatic functions express liver-enriched transcription factors, while dedifferentiated cells that have lost expression of all these hepatic functions no longer express HNF4 and HNF1. We describe a new heritable phenotype, designated as uncoupled, in which there is a spontaneous dissociation between the expression of these transcription factors and that of the hepatic functions. Cells presenting this phenotype, isolated from differentiated hepatoma cells, cease to accumulate all transcripts coding for hepatic functions but nevertheless maintain expression of HNF4 and HNF1. Transitory transfection experiments indicate that these two factors present in these cells have transcriptional activity similar to that of differentiated hepatoma cells. Characterization of the appropriate intertypic cell hybrids demonstrates that this new phenotype is recessive to the dedifferentiated state and fails to be complemented by differentiated cells. These results indicate the existence of mechanisms that inhibit transcription of genes coding for hepatocyte functions in spite of the presence of functional HNF4 and HNF1. Cells of the uncoupled phenotype present certain properties of oval cells described for pathological states of the liver.Genetic analysis of hepatoma-derived cell lines revealed, many years ago, that expression of differentiated functions is regulated in trans by mechanisms whose final effects are negative (extinction) or positive (activation) (78). More recent studies of these hepatoma lines further showed that maintenance of the hepatic phenotype is an active process operating at the level of transcription (21,42). By analysis of DNA sequences implicated in liver-specific transcription, the identification and cloning of members of four major families of liverenriched transcription factors (LETF) have been achieved. These families, each characterized by structurally related DNA binding domains, include the hepatocyte nuclear factor families HNF1, HNF3, and HNF4 and the CCAAT enhancer binding protein (C/EBP) family (13,82). Determination of the tissue distribution of these factors and analysis of their hierarchical relations led to the hypothesis that the combinatorial action of LETF together with the ubiquitous transcriptional machinery of the cell is necessary and maybe even sufficient for the maintenance of liver-specific gene transcription (30, 81). Indeed, the H4IIEC3 differentiated rat hepatoma cells and their derivatives that stably express an extensive set of adult hepatic functions express all the LETF identified to date, while in the rare dedifferentiated rat hepatoma cells that have lost expression of all these hepatic functions, HNF4 and HNF1 are systematically absent. In addition,...

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Section: Discussionmentioning

confidence: 97%

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confidence: 99%

Liver-Enriched Transcription Factors Uncoupled from Expression of Hepatic Functions in Hepatoma Cell Lines

Chaya

Fougère-Deschatrette

Weiss

1997

Molecular and Cellular Biology

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“…Till now, only the Hep G2-A16 clone has been derived from the ori ginal line and frequently been used for malaria research purposes. Seen the described obvious shift of the average characteristics of Hep G2 subpopulations (susceptibility for infection, biochemical properties and growth parameters) we believe that cloning should be the best tool in a selec tion procedure, combined with already described methods (Corcos and Weiss 1988). Cloning of the Hep G2 (London) cells proved to be not too easy (low cloning efficiency), but feasible.…”

Section: Discussionmentioning

confidence: 98%

Plasmodium berghei :susceptibility and growth characteristics of hepatoma cells as hosts for malaria schizonts

François

Desombere

Wéry

1991

Ann. Parasitol. Hum. Comp.

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Three different human hepatoma cell lines (Hep G2, London; Hep G2, Brussels; Mahlavu) have been compared with respect to susceptibility for in vitro infection with Plasmodium berghei sporozoites and subsequent development of mature schizonts and infectious merozoites. The results were very different, even with host cells derived from the same parent line. Both Hep G2 lines were able to function as host cells, but the Mahlavu line was completely refractory. Hep G2 (London) was even more susceptible than the Hep G2-A16 clone. Hepatoma cells harbouring young exoerythrocytic forms permitted their development to mature schi zonts and production of merozoites inside the intraperitoneal cavity of OF1 mice. Pronounced differences in growth parameters of subpopulations of Hep G2 cells were stated as well. Optimal condi tions for in vitro culture of the most suitable cell line were identi fied. Finally, the seeding, plating and cloning efficiencies were determined. Les résultats furent très différents, même entre 2 lignées cellu laires dérivées de la même souche parentale. Les 2 lignées Hep G2 se comportèrent en cellules hôtes, tandis que la lignée Mahlavu se montra totalement réfractaire. Hep G2 (Londres) fut plus sus ceptible que le clône Hep G2-16.Les cellules contenant des formes exoérythrocytaires jeunes per mirent leur développement en schizontes mûrs, dont le transfert dans la cavité péritonéale de souris OF1 entraîna la production de mérozoïtes et une parasitémie.Les sous-populations Hep G2 présentèrent une diversité mar quée de leurs paramètres de croissance. Les conditions optimales pour la culture in vitro de la lignée la plus susceptible furent pré cisées, de même que les indices d'efficacité d'ensemencement, d'éta lement et de clônage.

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Genetic analysis of aflatoxin B1 activation in rat hepatoma cells

Corcos

Rousset

Kiefer³

et al. 1990

Mol Gen Genet

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We present a strategy to elucidate the rate-limiting steps in activation of carcinogenic compounds by cytochromes P450. The principle was to select Reuber rat hepatoma cells for resistance to a procarcinogen. The hypothesis was that resistant cells should be systematically deficient in the P450 enzyme(s) involved in the activation process. Here we present an example of the use of this approach using aflatoxin B1 (AFB1), a potent hepatocarcinogen, as the selective agent. Parental cells as well as individual and pooled colonies selected for AFB1 resistance from three independent rat hepatoma lines were characterized for their content of 1) mRNA hybridizing to cDNA and/or oligonucleotide probes for cytochromes P450IIB1, P450IIB2 and albumin; and 2) aldrin epoxidase activity. Parental aflatoxin B1-sensitive cells were shown to express P450IIB1 but not P450IIB2. The majority of the aflatoxin B1-resistant clones failed to accumulate cytochrome P450IIB1 mRNA and expressed no or only very low aldrin epoxidase activity. Albumin mRNA levels remained unchanged, demonstrating that loss of expression of cytochrome P450IIB1 was not a consequence of a general dedifferentiation event. A revertant population showing restoration of both cytochrome P450IIB1 mRNA accumulation and aldrin epoxidase activity was fully sensitive to aflatoxin B1. The correlation between expression of cytochrome P450IIB1 and sensitivity to aflatoxin B1 in both parental cells and revertants strongly suggests that cytochrome P450IIB1 is a major contributor to the activation of aflatoxin B1 in rat hepatoma cells. The kind of strategy described here could be applied to other compounds that become cytotoxic for hepatoma cells following activation by cytochromes P450.

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Efficient one-step selection of hepatoma cell variants of a variety of phenotypes by use of aflatoxin B1

Cited by 4 publications

References 25 publications

Liver-Enriched Transcription Factors Uncoupled from Expression of Hepatic Functions in Hepatoma Cell Lines

Liver-Enriched Transcription Factors Uncoupled from Expression of Hepatic Functions in Hepatoma Cell Lines

Plasmodium berghei :susceptibility and growth characteristics of hepatoma cells as hosts for malaria schizonts

Genetic analysis of aflatoxin B1 activation in rat hepatoma cells

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