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

ABSTRACT: 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.

SUBMITTER: Monte M

PROVIDER: S-EPMC1544058 | biostudies-literature | 2006 Jul

REPOSITORIES: biostudies-literature

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

Monte Martin M Simonatto Marta M Peche Leticia Y LY Bublik Debora R DR Gobessi Stefania S Pierotti Marco A MA Rodolfo Monica M Schneider Claudio C

Proceedings of the National Academy of Sciences of the United States of America 20060717 30

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 et ...[more]

PMID: 16847267

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Project description:The cytochrome b5 domain containing 2 (CYB5D2; Neuferricin) protein has been reported to bind heme, however, the critical residues responsible for heme-binding are undefined. Furthermore, the relationship between heme-binding and CYB5D2-mediated intracellular functions remains unknown. Previous studies examining heme-binding in two cytochrome b5 heme-binding domain-containing proteins, damage-associated protein 1 (Dap1; Saccharomyces cerevisiae) and human progesterone receptor membrane component 1 (PGRMC1), have revealed that conserved tyrosine (Y) 73, Y79, aspartic acid (D) 86, and Y127 residues present in human CYB5D2 may be involved in heme-binding. CYB5D2 binds to type b heme, however, only the substitution of glycine (G) at D86 (D86G) within its cytochrome b5 heme-binding (cyt-b5) domain abolished its heme-binding ability. Both CYB5D2 and CYB5D2(D86G) localize to the endoplasmic reticulum. Ectopic CYB5D2 expression inhibited cell proliferation and anchorage-independent colony growth of HeLa cells. Conversely, CYB5D2 knockdown and ectopic CYB5D2(D86G) expression increased cell proliferation and colony growth. As PGRMC1 has been reported to regulate the expression and activities of cytochrome P450 proteins (CYPs), we examined the role of CYB5D2 in regulating the activities of CYPs involved in sterol synthesis (CYP51A1) and drug metabolism (CYP3A4). CYB5D2 co-localizes with cytochrome P450 reductase (CYPOR), while CYB5D2 knockdown reduced lanosterol demethylase (CYP51A1) levels and rendered HeLa cells sensitive to mevalonate. Additionally, knockdown of CYB5D2 reduced CYP3A4 activity. Lastly, CYB5D2 expression conferred HeLa cell survival from chemotherapeutic agents (paclitaxel, cisplatin and doxorubicin), with its ability to promote survival being dependent on its heme-binding ability. Taken together, this study provides evidence that heme-binding is critical for CYB5D2 in regulating HeLa cell growth and survival, with endogenous CYB5D2 being required to modulate CYP activities.

Dataset Information

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

Publications

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

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