Cancer testis antigens in human melanoma stem cells: expression, distribution, and methylation status.
Neoplastic populations with stem cell potential have been most recently identified in human cutaneous melanoma, and initially characterized for their phenotypic profile. Being melanoma stem cells (MSC) the most desirable target of therapeutic intervention, we asked whether they express the epigenetically-regulated cancer testis antigens (CTA) on which melanoma immunotherapy is increasingly focusing. Reverse transcription-PCR analyses identified the presence of the large majority of investigated CTA (i.e., MAGE, GAGE, NY-ESO, and SSX families) in different MSC populations. MSC expressed MAGE-A proteins as detected by western blot; noteworthy, the distribution of MAGE-A proteins was highly homogeneous within given MSC populations as shown by confocal immunofluorescence. Promoter methylation studies unveiled a homogeneously-demethylated MAGE-A3 promoter that paired MAGE-A3 expression in MSC. Altogether these findings demonstrate that MSC can be efficiently targeted by CTA-directed immunotherapeutic approaches, and suggest that epigenetic patterns most likely drive the expression of CTA in MSC as previously shown for melanoma cells.
Sigalotti
Luca
L
Cancer Bioimmunotherapy Unit, Department of Medical Oncology, Centro di Riferimento Oncologico, Istituto di Ricovero e Cura a Carattere Scientifico, Aviano, Italy.
Covre
Alessia
A
Zabierowski
Susan
S
Himes
Benjamin
B
Colizzi
Francesca
F
Natali
Pier Giorgio
PG
Herlyn
Meenhard
M
Maio
Michele
M
D000951:Antigens, Neoplasm / Q000235:genetics* / Q000378:metabolism*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D005455:Fluorescent Antibody Technique; D006801:Humans; D008297:Male; D008545:Melanoma / Q000378:metabolism* / Q000473:pathology; D018613:Microscopy, Confocal; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000378:metabolism*; D013737:Testis / Q000276:immunology*; D014018:Tissue Distribution
D000951:Antigens, Neoplasm