The objective of this study was to identify and characterize a self-renewing subpopulation of human ovarian tumor cells (ovarian cancer-initiating cells, OCICs) fully capable of serial propagation of their original tumor phenotype in animals.

Common sites of breast cancer metastasis include the lung, liver, and bone, and of these secondary metastatic sites, estrogen receptor A (ERA)-positive breast cancer often favors bone. Within secondary organs, cancer cells would predictably encounter tissue-specific fibroblasts or their soluble factors, yet our understanding of how tissue-specific fibroblasts directly affect cancer cell growth rates and survival remains largely unknown. Therefore, we tested the hypothesis that mesenchymal fibroblasts isolated from common sites of breast cancer metastasis provide a more favorable microenvironment with respect to tumor growth rates. We found a direct correlation between the ability of breast, lung, and bone fibroblasts to enhance ERA-positive breast cancer cell growth and the level of soluble interleukin-6 (IL-6) produced by each organ-specific fibroblast, and fibroblast-mediated growth enhancement was inhibited by the removal or inhibition of IL-6. Interestingly, mice coinjected with MCF-7 breast tumor cells and senescent skin fibroblasts, which secrete IL-6, developed tumors, whereas mice coinjected with presenescent skin fibroblasts that produce little to no IL-6 failed to form xenograft tumors. We subsequently determined that IL-6 promoted growth and invasion of breast cancer cells through signal transducer and activator of transcription 3-dependent up-regulation of Notch-3, Jagged-1, and carbonic anhydrase IX. These data suggest that tissue-specific fibroblasts and the factors they produce can promote breast cancer disease progression and may represent attractive targets for development of new therapeutics. [Cancer Res 2008;68(21):9087-95]

Testing for DNA methylation has potential in cancer screening. Most previous studies of DNA methylation in cervical cancer used a candidate gene approach. The aim our study was to identify novel genes that are methylated in cervical cancers and to test their potential in clinical applications. We did a differential methylation hybridization using a CpG island (CGI) microarray containing 8640 CGI tags to uncover methylated genes in squamous cell carcinomas (SCC) of the uterine cervix. Pooled DNA from cancer tissues and normal cervical swabs were used for comparison. Methylation-specific polymerase chain reaction, bisulfite sequencing and reverse transcription polymerase chain reaction were used to confirm the methylation status in cell lines, normal cervices (n 5 45), low-grade lesions (n 5 45), high-grade lesions (HSIL; n 5 58) and invasive squamous cell carcinomas (SCC; n 5 22 from swabs and n 5 109 from tissues). Human papillomavirus (HPV) was detected using reverse line blots. We reported 6 genes (SOX1, PAX1, LMX1A, NKX6-1, WT1 and ONECUT1) more frequently methylated in SCC tissues (81.5, 94.4, 89.9, 80.4, 77.8 and 20.4%, respectively) than in their normal controls (2.2, 0, 6.7, 11.9, 11.1 and 0%, respectively; p < 0.0001). Parallel testing of HPV and PAX1 methylation in cervical swabs confers an improved sensitivity than HPV testing alone (80% vs. 66%) without compromising specificity (63% vs. 64%) for HSIL/SCC. Testing PAX1 methylation marker alone, the specificity for HSIL/SCC is 99%. The analysis of these novel DNA methylations may be a promising approach for the screening of cervical cancers. ' 2008 Wiley-Liss, Inc.Key words: cervical cancer; epigenetics; hpv; methylation; microarray In addition to genetic changes, epigenetic alterations such as DNA methylation and histone modifications can result in heritable gene silencing without changes to genetic sequences and are recognized as important causes of cancer.1-3 DNA methylation mostly occurs at the 5 0 cytosine in the palindromic sequence, 5 0 -CpG-3 0 . CpG islands are CpG-rich areas of 1 kb that are usually located in the vicinity of genes, often near the promoters of widely expressed genes.4,5 Methylation of CpG sites in the human genome is catalyzed by a family of DNA methyltransferases (DNMTs). DNMT1 is a maintenance methyltransferase with a preference for hemimethylated DNA whereas DNMT3a and DNMT3b are de novo methyltransferases with approximately equal preferences for methylated and unmethylated DNA.2,6 The addition of methyl groups by DNMTs recruits complexes with transcription repressors that modify histones and thus silence genes. Global DNA hypomethylation and site-specific hypermethylation result in genomic instability and transcriptional gene inactivation, respectively, both of which are associated with cancer. 7,8 As epigenetic silencing of tumor suppressor genes by promoter hypermethylation is commonly observed in human cancers, DNA methylation could serve as a marker for early diagnosis of cancer and as a means of assessing the prognos...

Estrogen imprinting is used to describe a phenomenon in which early developmental exposure to endocrine disruptors increases breast cancer risk later in adult life. We propose that long-lived, self-regenerating stem and progenitor cells are more susceptible to the exposure injury than terminally differentiated epithelial cells in the breast duct. Mammospheres, containing enriched breast progenitors, were used as an exposure system to simulate this imprinting phenomenon in vitro. Using MeDIP-chip, a methylation microarray screening method, we found that 0.5% (120 loci) of human CpG islands were hypermethylated in epithelial cells derived from estrogenexposed progenitors compared with the non-estrogen-exposed control cells. This epigenetic event may lead to progressive silencing of tumor suppressor genes, including RUNX3, in these epithelial cells, which also occurred in primary breast tumors. Furthermore, normal tissue in close proximity to the tumor site also displayed RUNX3 hypermethylation, suggesting that this aberrant event occurs in early breast carcinogenesis. The high prevalence of estrogen-induced epigenetic changes in primary tumors and the surrounding histologically normal tissues provides the first empirical link between estrogen injury of breast stem/progenitor cells and carcinogenesis. This finding also offers a mechanistic explanation as to why a tumor suppressor gene, such as RUNX3, can be heritably silenced by epigenetic mechanisms in breast cancer. [Cancer Res 2008;68(6):1786-96]