MAGE-A tumor antigens target p53 transactivation function through histone deacetylase recruitment and confer resistance to chemotherapeutic agents.

The MAGE gene family is characterized by a conserved domain (MAGE Homology Domain). A subset of highly homologous MAGE genes (group A; MAGE-A) belong to the chromosome X-clustered cancer/testis antigens. MAGE-A genes are normally expressed in the human germ line and overexpressed in various tumor types; however, their biological function ...
is largely unknown. Here we present evidence indicating that MageA2 protein, belonging to the MAGE-A subfamily, confers wild-type-p53-sensitive resistance to etoposide (ET) by inducing a novel p53 inhibitory loop involving recruitment of histone deacetylase 3 (HDAC3) to MageA2/p53 complex, thus strongly down-regulating p53 transactivation function. In fact, enhanced MageA2 protein levels, in addition to ET resistance, correlate with impaired acetylation of both p53 and histones surrounding p53-binding sites. Association between MAGE-A expression levels and resistance to ET treatment is clearly shown in short-term cell lines obtained from melanoma biopsies harboring wild-type-p53, whereas cells naturally, or siRNA-mediated expressing low MAGE-A levels, correlate with enhanced p53-dependent sensitivity to ET. In addition, combined trichostatin A/ET treatment in melanoma cells expressing high MAGE-A levels reestablishes p53 response and reverts the chemoresistance.
Mesh Terms:
Antigens, Neoplasm, Antineoplastic Agents, Apoptosis, Cell Line, Tumor, DNA Damage, Drug Resistance, Neoplasm, Gene Expression Regulation, Neoplastic, Histone Deacetylases, Humans, Hydroxamic Acids, Melanoma, Neoplasm Proteins, Protein Structure, Tertiary, Transcriptional Activation, Tumor Suppressor Protein p53
Proc. Natl. Acad. Sci. U.S.A.
Date: Jul. 25, 2006
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