Potential role of 5-aza-2'-deoxycytidine induced MAGE-A4 expression in immunotherapy for anaplastic thyroid cancer

Surgery. 2013 Dec;154(6):1456-62; discussion 1462. doi: 10.1016/j.surg.2013.07.009.

Abstract

Background: Melanoma antigen gene family (MAGE)-A4, a member of the cancer testis antigen family, has been reported in various cancers including melanoma, bladder, head and neck, oral, and lung, and is a potential target for T-cell-receptor-based immunotherapy. Baseline expression levels of the MAGE-A4 gene in thyroid cancer cell lines have not been previously studied thoroughly.

Methods: Human thyroid cancer cell lines (8505c, HTh7, BCPAP, and TPC-1) were treated with either 10 μmol/L 5'-azacytidine (Aza) or 10 μmol/L 5-AZA-2'deoxycytidine (DAC) and evaluated for various MAGEA gene expression. Later melanoma cell lines A375 and 8505c were treated with PLX4720 in combination with DAC and evaluated for MAGE-A4 expression.

Results: Only BCPAP cells expressed moderate levels of MAGE-A3 and MAGE-A6 at baseline. Treatment with DAC/Aza induced the expression of MAGE-A4 and MAGE-A1 in 8505c cells. PLX4720 treatment did not affect MAGE-A4 expression in 8505c cells, but increased its expression in A375 cells. In contrast, addition of PLX4720 to DAC-treated 8505c cells decreased the previously induced MAGE-A4 expression by DAC in these cells. A similar decrease in MAGE-A4 expression by DAC was also seen in 8505cBRAF(-/-) cells. Although DAC treatment resulted in demethylation of the MAGE-A4 promoter in 2 CpG sites, PLX addition to DAC did not affect the demethylation status.

Conclusion: Demethylating agents increased the expression of MAGE genes in thyroid cancer cells. The effect of BRAFV600E inhibitors on MAGE-A4 expression suggest the role of downstream MEK/BRAF signaling in its expression apart from promoter demethylation being the sole requirement. Expression of MAGE-A4 may make immunotherapeutic intervention possible in selected patients with thyroid cancer.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Antigens, Neoplasm / genetics*
  • Azacitidine / analogs & derivatives*
  • Azacitidine / pharmacology
  • Cell Line, Tumor
  • CpG Islands
  • DNA Methylation / drug effects
  • DNA Methylation / genetics
  • Decitabine
  • Gene Expression / drug effects
  • Humans
  • Immunotherapy / methods*
  • Indoles / pharmacology
  • MAP Kinase Signaling System / drug effects
  • Melanoma / genetics
  • Melanoma / immunology
  • Melanoma / therapy
  • Neoplasm Proteins / genetics*
  • Promoter Regions, Genetic / drug effects
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors
  • Proto-Oncogene Proteins B-raf / genetics
  • Proto-Oncogene Proteins B-raf / metabolism
  • Sulfonamides / pharmacology
  • Thyroid Carcinoma, Anaplastic
  • Thyroid Neoplasms / genetics
  • Thyroid Neoplasms / immunology
  • Thyroid Neoplasms / therapy*

Substances

  • Antigens, Neoplasm
  • Indoles
  • MAGEA4 protein, human
  • Neoplasm Proteins
  • PLX 4720
  • Sulfonamides
  • Decitabine
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • Azacitidine