Hepatoma cells are a promising cell source for the construction of bioartificial liver (BAL) systems owing to their high proliferative capability. However, their low liver function compared with primary hepatocytes is a major problem. In a previous study, we established a genetically modified hepatoma cell line, Hepa/8F5, in which eight liver-enriched transcription factor (LETF) genes were transduced into mouse hepatoma Hepa1-6 cells using a drug-inducible transactivator system. These cells proliferate actively under normal culture conditions, meaning that large quantities can be prepared easily. When the overexpression of the LETFs is induced by the addition of an inducer drug, cell growth stops and cell morphology changes with concomitant high expression of liver functions. However, the liver functions largely depend on the presence of the inducer drug, which must be continuously added to maintain these enhanced functions. In the present study, we attempted to modify the method of induction of LETF overexpression in Hepa/8F5 cells to remove the requirement for continual drug addition. To this end, we constructed a system in which the artificial transactivator was transcribed and amplified under the control of a heat-shock protein promoter, and introduced the system into the genome of Hepa/8F5 cells. In our modified cell line, heat-triggered LETF expression was confirmed to induce high liver function. After drug-screening of transfected cells, we established a hepatoma cell line (Hepa/HS), which exhibited high, heat-inducible liver functions. The Hepa/HS cells may represent a new cell source for hepatic studies such as the construction of BAL systems.
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