There are several potential limitations in this meta-analysis

jority of the samples included in our analysis were obtained during the proliferative phase. Moreover, it is challenging to date the endometrium for cycle phase since many women with uterine leiomyomas have irregular cycles with prolonged bleeding. The small number of secretory phase samples did not permit us to compare biological differences as a function of the cycle phase. Since the correlation between differences in DNA methylation and gene expression was evaluated in paired samples from the same patient, the effect of cycle phase on this analysis was further minimized. In this study, we noted a key epigenetic mechanism whereby increased promoter methylation leads to transcriptional suppression in uterine leiomyoma compared with matched normal myometrial tissues. The second predominant mechanism was hypomethylation associated with overexpression of genes indicating an overall inverse relationship between DNA methylation and gene expression in uterine leiomyoma. However, we also observed some genes to be hypermethylated and upregulated, and other genes to be hypomethylated and downregulated. The absence of an inverse relationship between promoter DNA methylation and mRNA expression in this minor group of genes is consistent with previously published data. For example, methylation of one particular CpG island in the NR5A1 gene is associated with transcriptional suppression, whereas methylation of another CpG island located 4 kb downstream is associated with 12829792 overexpression ” of NR5A1 mRNA. It is conceivable that the effects of a single methylated CpG island on gene expression may be either gene-specific or location-specific within the same gene. We DM-1 verified the effects of promoter DNA methylation on transcriptional inhibition of three tumor suppressor genes namely, KLF11, DLEC1, and KRT19. KLF11 is a transcription factor and a member of the transforming growth factor beta family, which is involved in key cellular functions such as apoptosis, proliferation, and differentiation. KLF11 is expressed in a number of human tissues, and it is repressed in several human cancers. It inhibits neoplastic transformation and cell growth both in vivo and in vitro. We previously demonstrated the downregulation of KLF11 expression in uterine leiomyoma tissues compared with normal matched myometrial tissue. Although the mechanism involved in KLF11-regulated cell proliferation is not fully understood, we demonstrated for the Genome-Wide DNA Methylation in Uterine Leiomyoma 7 Genome-Wide DNA Methylation in Uterine Leiomyoma first time that KLF11 is epigenetically regulated by DNA methylation, with hypermethylation correlating with a repressed state in uterine leiomyoma. Recently, KLF11 was also shown to be aberrantly hypermethylated in myelodysplastic syndromes. It has been suggested that KLF11 inhibits gene expression through a Sin3a-HDAC interacting domain and recruitment of the corepressor mSin3a. We plan to investigate this mechanism further, and identify the DNMTs and DNA methyl binding proteins that are involved in silencing of KLF11. DLEC1 is an epigenetically modified tumor suppressor gene. DLEC1 is localized in the cytoplasm ubiquitously expressed in all human tissues, and repressed in several human cancers. Hypermethylation of the DLEC1 promoter is associated with its transcriptional repression in a wide variety of malignant tumors originating from lung, esophagus, kidney, ovary, nasopharynx, and liver. The DLEC1 promoter region contains a CpG isl