Induction of MAGE-3 expression in lung and esophageal cancer cells.
BACKGROUND
Although MAGE-3 has been detected in approximately 40% of lung and esophageal cancers, expression of this cancer testis antigen appears to be below the threshold for immune recognition in patients with these malignancies. The aim of this study was to determine if the demethylating agent, 5-Aza-2'-deoxycytidine (DAC) and if the histone deacetylase inhibitor Depsipeptide FR901228 (DP) could enhance MAGE-3 expression in lung and esophageal cancer cells.


METHODS
Eleven lung and esophageal cancer lines and cultured normal human bronchial epithelial (NHBE) cells were exposed to normal media (NM), DAC, DP, or combination DAC/DP at varying concentrations and exposure durations. MAGE-3 expression was evaluated by quantitative RT-PCR (TaqMan) and immunohistochemistry techniques. Trypan blue exclusion techniques were used to examine the proliferation of cancer cells after drug exposure.


RESULTS
Relative to untreated controls, MAGE-3 expression was enhanced 32-fold (range 3.9 to 110) by DAC alone (0.1 micromol/L x 72 h), 2.1-fold (0.4 to 4.2) by DP alone (25 ng/mL x 6h), and 57-fold (4.6 to 209) by sequential DAC/DP exposure. Increased MAGE-3 mRNA copy numbers coincided with enhanced protein levels in these cells. MAGE-3 expression persisted after drug exposure. Flow cytometry confirmed the presence of functional HLA class I expression in these cells. Sequential DAC/DP treatment mediated pronounced growth inhibition in cancer cells but not NHBE.


CONCLUSIONS
Sequential DAC/DP treatment may be a novel strategy to simultaneously augment MAGE-3 expression and induce growth arrest in thoracic malignancies.
Weiser
T S
TS
Thoracic Oncology Section, Surgery Branch, National Cancer Institute, Bethesda, Maryland 20892-1502, USA.
Ohnmacht
G A
GA
Guo
Z S
ZS
Fischette
M R
MR
Chen
G A
GA
Hong
J A
JA
Nguyen
D M
DM
Schrump
D S
DS
D000230:Adenocarcinoma / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000951:Antigens, Neoplasm / Q000378:metabolism*; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism; D015254:DNA Modification Methylases / Q000037:antagonists & inhibitors; D000077209:Decitabine; D047630:Depsipeptides; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004938:Esophageal Neoplasms / Q000378:metabolism*; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D007150:Immunohistochemistry; D008175:Lung Neoplasms / Q000378:metabolism*; D008545:Melanoma / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D010456:Peptides, Cyclic; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000900:Anti-Bacterial Agents; D000903:Antibiotics, Antineoplastic; D000951:Antigens, Neoplasm; D047630:Depsipeptides; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; C072013:MAGEA3 protein, human; D009363:Neoplasm Proteins; D010456:Peptides, Cyclic; D012333:RNA, Messenger; D000077209:Decitabine; C087123:romidepsin; D015254:DNA Modification Methylases; D001374:Azacitidine