Linked Life Data

15604288

Source:http://linkedlifedata.com/resource/pubmed/id/15604288

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
24
pubmed:dateCreated
2004-12-17
pubmed:abstractText
Cancer/testis antigens (CTA) are suitable targets for immunotherapy of human malignancies, and clinical trials are mainly focusing on MAGE-A3. However, the heterogeneous intratumor expression of CTA may hamper the effectiveness of CTA-directed vaccination through the emergence of CTA-negative neoplastic clones. We investigated the intratumor heterogeneity of CTA in human melanoma and the underlying molecular mechanism(s) at clonal level using 14 single cell clones generated from the melanoma lesion Mel 313. Reverse transcription-PCR revealed a highly heterogeneous expression of MAGE-A1, -A2, -A3, -A4, -A6, GAGE 1-6, SSX 1-5, and PRAME among melanoma clones. Only nine clones expressed MAGE-A3 and competitive reverse transcription-PCR identified relative differences in the number of mRNA molecules of up to 130-fold between clones 5 and 14. This clonal heterogeneity of MAGE-A3 expression correlated with the methylation status of specific CpG dinucleotides in MAGE-A3 promoter: i.e., hypomethylated CpG dinucleotides at positions -321, -151, -19, -16, -5, -2, +21, and +42 were found in clones expressing high but not low levels of MAGE-A3. Supporting the role of DNA methylation in generating the intratumor heterogeneity of CTA, the DNA hypomethylating agent 5-aza-2'-deoxycytidine (5-AZA-dCyd) invariably induced their expression in all CTA-negative clones. Furthermore, 5-AZA-dCyd-treatment reduced to 6 folds the differential expression of MAGE-A3 between clones 5 and 14, which became recognized to a similar extent by T cells specific for a MAGE-A-encoded peptide. These findings identify promoter methylation as directly responsible for the intratumoral heterogeneity of therapeutic CTA in melanoma and foresee the use of 5-AZA-dCyd to overcome the limitations set by their intratumor heterogeneous expression to CTA-based vaccine therapy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0008-5472
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
64
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9167-71
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Intratumor heterogeneity of cancer/testis antigens expression in human cutaneous melanoma is methylation-regulated and functionally reverted by 5-aza-2'-deoxycytidine.
pubmed:affiliation
Cancer Bioimmunotherapy Unit, Department of Medical Oncology, Centro di Riferimento Oncologico, Istituto di Ricovero e Cura a Carattere Scientifico, Aviano, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't