Effect of 5-aminolevulinic acid on the expression of carcinogenesis-related proteins in cultured primary hepatocytes
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Acute intermittent porphyria (AIP) is a heme pathway disorder caused by a decrease in the activity and synthesis of porphobilinogen deaminase. Thus, the first heme precursor 5-aminolevulinic acid (ALA) accumulates in the liver. Reactive oxygen species (ROS) resulting from ALA oxidation may be correlated to a higher incidence of hepatocellular carcinoma (HCC) in AIP patients. However, the molecular mechanisms of this relationship have not been thoroughly elucidated to date. In this study, we investigated the effect of increasing levels of ALA on the expression of proteins related to DNA repair, oxidative stress, apoptosis, proliferation and lipid metabolism. Primary rat hepatocytes were isolated by the collagenase perfusion method, lipoperoxidation was evaluated by a TBA fluorimetric assay and Western blotting was used to assess protein abundance. The data showed that ALA treatment promoted a dose-dependent increase of p53 expression, downregulation of Bcl-2, HMG-CoA reductase and OGG1 and an increase in lipoperoxidation. There was no alteration in the expression of the transcription factor NF-κB, catalase and superoxide dismutase. ALA oxidation products induced protein regulation patterns, suggesting the interconnection of cellular processes, such as the intrinsic pathway of apoptosis, redox homeostasis, cell proliferation, lipid metabolism and DNA repair. This study helps to elucidate the molecular mechanisms of hepatotoxicity mediated by ALA pro-oxidant effects and supports the hypothesis that ALA accumulation correlates with a higher incidence of hepatic carcinogenic events.
Keywords5-Aminolevulinic acid Acute intermittent porphyria Hepatocellular carcinoma Protein expression Reactive oxygen species Primary rat hepatocytes
β-Cell lymphoma 2
8-Oxoguanine DNA glycosylase I
Acute intermittent porphyria
Glyceraldehyde 3-phosphate dehydrogenase
Nuclear factor κB
Reactive oxygen species
Tumor protein p53
This work was supported by the “Fundação de Amparo à Pesquisa do Estado de São Paulo” FAPESP (Grants: 07/01966-5 and 10/51068-6). PRM and CBG received fellowships from “Coordenação de Aperfeiçoamento de Pessoal de Nível Superior” - CAPES (Biotechnology Program-USP-33002010156PO and “Programa de Estudantes-Convênio de Pós-Graduação”-PEC-PG notice 042/2012)”.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
The experimental procedure was approved by the animal ethics committee of Butantan Institute (CEUAIB 755/10) and was performed in accordance with the U.K. Animals (Scientific Procedures) Act, 1986 and the associated guidelines, the EU Directive 2010/63/EU for animal experiments and complied with the ARRIVE guidelines.
Research involving human participants
All authors declare that this article does not contain any studies with human participants performed by any of the authors.
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