Intertumor and intratumor NY-ESO-1 expression heterogeneity is associated with promoter-specific and global DNA methylation status in ovarian cancer.
OBJECTIVE
The cancer/germline antigen NY-ESO-1 is variably expressed in epithelial ovarian cancer (EOC), with most tumors showing low or heterogeneous expression, which limits patient responses to NY-ESO-1 vaccine therapy. We tested the hypothesis that promoter and global genomic DNA methylation status correlates with intertumor and intratumor NY-ESO-1 expression status in EOC.


METHODS
We utilized 78 EOC tumors and 10 normal ovary controls for quantitative DNA methylation analyses and NY-ESO-1 expression analysis by immunohistochemistry (IHC) and quantitative reverse transcriptase PCR. A subset of EOC tumors were used to perform microdissections of NY-ESO-1 IHC-positive and NY-ESO-1 IHC-negative tissue regions, followed by DNA methylation analyses. EOC cell lines were treated in vitro with decitabine to determine the functional contribution of DNA methylation to NY-ESO-1 gene regulation in EOC.


RESULTS
Compared with normal ovary, bulk EOC tissues display increased NY-ESO-1 expression, reduced NY-ESO-1 promoter methylation, and reduced LINE-1 DNA methylation. However, NY-ESO-1 expression is not significantly associated with NY-ESO-1 promoter methylation status in bulk tumors. We hypothesized that this resulted from heterogeneous intratumor NY-ESO-1 expression. Supporting this idea, experiments using microdissected material revealed that intertumor and intratumor NY-ESO-1 expression heterogeneity is significantly correlated with promoter and global DNA methylation status in EOC. Moreover, decitabine treatment functionally restored NY-ESO-1 expression in nonexpressing EOC cell lines.


CONCLUSIONS
DNA methylation status is associated with both intertumor and intratumor NY-ESO-1 expression status in EOC. These findings support a novel chemoimmunotherapy approach using decitabine to augment NY-ESO-1 vaccine therapy for treatment of recurrent EOC.
Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Anna
A
Woloszynska-Read
Paulette
P
Mhawech-Fauceglia
Jihnhee
J
Yu
Kunle
K
Odunsi
Adam R
AR
Karpf
D000951:Antigens, Neoplasm / Q000096:biosynthesis / Q000235:genetics*; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000951:Antigens, Neoplasm; C104948:CTAG1B protein, human; D008565:Membrane Proteins