Epigenetic regulation of maspin expression in human ovarian carcinoma cells.
OBJECTIVE
Maspin expression is often deregulated in human cancer cells compared to their normal cells due to loss of epigenetic control. In contrast to normal human ovarian surface epithelial (HOSE) cells, ovarian carcinoma cells display a gain of maspin mRNA expression. The objective of this study was to determine whether gain of maspin expression in ovarian cancer is governed by epigenetic mechanisms.


METHODS
We examined the cytosine methylation and chromatin accessibility status of the maspin promoter in normal HOSE cells and ovarian carcinoma cells with real-time RT-PCR, sodium bisulfite genomic sequencing, and chromatin accessibility assays. 5-Aza-2'-deoxycytidine (5-aza-dC) was used to induce demethylation of the maspin promoter. Ad p53 was used to induce transient overexpression of wild-type p53.


RESULTS
Normal HOSE cells were maspin-negative in association with methylation of the maspin promoter. In the maspin-positive ovarian cancer cell lines, the maspin promoter was unmethylated. Increased maspin expression in ovarian carcinoma cells was accompanied by a more accessible chromatin structure in the maspin promoter. In the maspin-negative ovarian cancer cell line A222, maspin could be induced following 5-aza-dC treatment or by forced overexpression of p53.


CONCLUSIONS
These results suggest that changes in cytosine methylation and chromatin accessibility play an important role in maspin expression in human ovarian carcinoma. Deregulation of maspin expression in ovarian cancer is due to loss of epigenetic control as has been shown in other cancers. This observation provides further evidence of the strict epigenetic control of the maspin gene.
Rose
Stephen L
SL
Department of Obstetrics and Gynecology, The University of Iowa Hospitals and Clinics, The Holden Comprehensive Cancer Center, 4630 John Colloton Pavilion, 200 Hawkins Drive, Iowa City, IA 52242, USA.
Fitzgerald
Matthew P
MP
White
Natalie O
NO
Hitchler
Michael J
MJ
Futscher
Bernard W
BW
De Geest
Koen
K
Domann
Frederick E
FE
D002843:Chromatin / Q000235:genetics; D019175:DNA Methylation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015843:Serpins / Q000096:biosynthesis / Q000235:genetics*
D002843:Chromatin; D012333:RNA, Messenger; C085344:SERPIN-B5; D015843:Serpins