Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma.

Article Details

Citation

Martinez-Chantar ML, Garcia-Trevijano ER, Latasa MU, Martin-Duce A, Fortes P, Caballeria J, Avila MA, Mato JM

Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma.

Gastroenterology. 2003 Apr;124(4):940-8.

PubMed ID
12671891 [ View in PubMed
]
Abstract

BACKGROUND & AIMS: Of the 2 genes (MAT1A, MAT2A) encoding methionine adenosyltransferase, the enzyme that synthesizes S-adenosylmethionine, MAT1A, is expressed in liver, whereas MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. Here, we identified the beta subunit as a regulator of proliferation in human hepatoma cell lines. The beta subunit has been cloned and shown to lower the K(m) of methionine adenosyltransferase II alpha2 (the MAT2A product) for methionine and to render the enzyme more susceptible to S-adenosylmethionine inhibition. METHODS: Methionine adenosyltransferase II alpha2 and beta subunit expression was analyzed in human and rat liver and hepatoma cell lines and their interaction studied in HuH7 cells. beta Subunit expression was up- and down-regulated in human hepatoma cell lines and the effect on DNA synthesis determined. RESULTS: We found that beta subunit is expressed in rat extrahepatic tissues but not in normal liver. In human liver, beta subunit expression associates with cirrhosis and hepatoma. beta Subunit is expressed in most (HepG2, PLC, and Hep3B) but not all (HuH7) hepatoma cell lines. Transfection of beta subunit reduced S-adenosylmethionine content and stimulated DNA synthesis in HuH7 cells, whereas down-regulation of beta subunit expression diminished DNA synthesis in HepG2. The interaction between methionine adenosyltransferase II alpha2 and beta subunit was demonstrated in HuH7 cells. CONCLUSIONS: Our findings indicate that beta subunit associates with cirrhosis and cancer providing a proliferative advantage in hepatoma cells through its interaction with methionine adenosyltransferase II alpha2 and down-regulation of S-adenosylmethionine levels.

DrugBank Data that Cites this Article

Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
AdemetionineS-adenosylmethionine synthase isoform type-1ProteinHumans
Unknown
Cofactor
Details
AdemetionineS-adenosylmethionine synthase isoform type-2ProteinHumans
Unknown
Cofactor
Details
Polypeptides
NameUniProt ID
Methionine adenosyltransferase 2 subunit betaQ9NZL9Details