An epigenome-wide analysis of socioeconomic position and tumor DNA methylation in breast cancer patients.

BACKGROUND: Disadvantaged socioeconomic position (SEP), including lower educational attainment and household income, may influence cancer risk and outcomes. We hypothesized that DNA methylation could function as an intermediary epigenetic mechanism that internalizes and reflects the biological impact of SEP. METHODS: Based on tumor DNA methylation data from the Illumina 450 K array from 694 breast cancer patients in the Women's Circle of Health Study, we conducted an epigenome-wide analysis in relation to educational attainment and household income. Functional impact of the identified CpG sites was explored in silico using data from publicly available databases. RESULTS: We identified 25 CpG sites associated with household income at an array-wide significance level, but none with educational attainment. Two of the top CpG sites, cg00452016 and cg01667837, were in promoter regions of NNT and GPR37, respectively, with multiple epigenetic regulatory features identified in each region. NNT is involved in ß-adrenergic stress signaling and inflammatory responses, whereas GPR37 is involved in neurological and immune responses. For both loci, gene expression was inversely correlated to the levels of DNA methylation. The associations were consistent between Black and White women and did not differ by tumor estrogen receptor (ER) status. CONCLUSIONS: In a large breast cancer patient population, we discovered evidence of the significant biological impact of household income on the tumor DNA methylome, including genes in the ß-adrenergic stress and immune response pathways. Our findings support biological effects of socioeconomic status on tumor tissues, which might be relevant to cancer development and progression.

Deletion of Foxa1 in the mouse mammary gland results in abnormal accumulation of luminal progenitor cells: a link between reproductive factors and ER-/TNBC breast cancer?

In humans, parity without breastfeeding increases risk of estrogen receptor-negative (ER-) breast cancer and is associated with hypermethylation of FOXA1, a pioneer factor regulating lineage commitment of mammary gland luminal progenitor cells. We postulate that pregnancy-associated repression of FOXA1 results in the accumulation of aberrant, differentiation-arrested luminal progenitor cells which, following additional genetic and epigenetic insults, may give rise to ER- tumors. Consistent with this hypothesis, we show that deletion of Foxa1 in the mouse mammary gland results in a two-fold increase in the proportion of luminal progenitor cells and a reduction in mammary gland epithelial cells that stain positive for ER. These results provide compelling support for the notion that reduced Foxa1 expression is sufficient to alter mammary gland luminal cell fate determination in vivo, which could be a mechanism linking parity with ER- breast cancer.

FOXA1 Protein Expression in ER+ and ER- Breast Cancer in Relation to Parity and Breastfeeding in Black and White Women.

BACKGROUND: Forkhead box protein A1 (FOXA1) promotes luminal differentiation, and hypermethylation of the gene can be a mechanism of developing estrogen receptor-negative (ER-) breast cancer. We examined FOXA1 in breast tumor and adjacent normal tissue in relation to reproductive factors, particularly higher parity and no breastfeeding, that are associated with ER- tumors. METHODS: We performed IHC for FOXA1 in breast tumors (n = 1,329) and adjacent normal tissues (n = 298) in the Women's Circle of Health Study (949 Blacks and 380 Whites). Protein expression levels were summarized by histology (H) scores. Generalized linear models were used to assess FOXA1 protein expression in relation to reproductive factors by ER status. RESULTS: ER-positive (ER+) versus ER- tumors had higher FOXA1 protein expression (P < 0.001). FOXA1 expression was higher in tumor versus paired adjacent normal tissue in women with ER+ or non-triple-negative cancer (both P < 0.001), but not in those with ER- or triple-negative cancer. Higher number of births (1, 2, and 3+) was associated with lower FOXA1 protein expression in ER+ tumors [differences in H score, or ß = -8.5; 95% confidence interval (CI), -15.1 to -2.0], particularly among parous women who never breastfed (ß = -10.4; 95% CI, -19.7 to -1.0), but not among those who breastfed (ß = -7.5; 95% CI, -16.9 to 1.8). The associations for ER- tumors were similar, although they were not statistically significant. CONCLUSIONS: In this tumor-based study, higher parity was associated with lower FOXA1 expression in ER+ tumors, and breastfeeding may ameliorate the influence. IMPACT: These findings contribute to our understanding of FOXA1 methylation and breast cancer etiology.

BORIS Expression in Ovarian Cancer Precursor Cells Alters the CTCF Cistrome and Enhances Invasiveness through GALNT14.

High-grade serous carcinoma (HGSC) is the most aggressive and predominant form of epithelial ovarian cancer and the leading cause of gynecologic cancer-related death. We have previously shown that CTCFL (also known as BORIS, Brother of the Regulator of Imprinted Sites) is expressed in most ovarian cancers, and is associated with global and promoter-specific DNA hypomethylation, advanced tumor stage, and poor prognosis. To explore its role in HGSC, we expressed BORIS in human fallopian tube secretory epithelial cells (FTSEC), the presumptive cells of origin for HGSC. BORIS-expressing cells exhibited increased motility and invasion, and BORIS expression was associated with alterations in several cancer-associated gene expression networks, including fatty acid metabolism, TNF signaling, cell migration, and ECM-receptor interactions. Importantly, GALNT14, a glycosyltransferase gene implicated in cancer cell migration and invasion, was highly induced by BORIS, and GALNT14 knockdown significantly abrogated BORIS-induced cell motility and invasion. In addition, in silico analyses provided evidence for BORIS and GALNT14 coexpression in several cancers. Finally, ChIP-seq demonstrated that expression of BORIS was associated with de novo and enhanced binding of CTCF at hundreds of loci, many of which correlated with activation of transcription at target genes, including GALNT14. Taken together, our data indicate that BORIS may promote cell motility and invasion in HGSC via upregulation of GALNT14, and suggests BORIS as a potential therapeutic target in this malignancy. IMPLICATIONS: These studies provide evidence that aberrant expression of BORIS may play a role in the progression to HGSC by enhancing the migratory and invasive properties of FTSEC.

Blocked transcription through KvDMR1 results in absence of methylation and gene silencing resembling Beckwith-Wiedemann syndrome.

The maternally methylated KvDMR1 ICR regulates imprinted expression of a cluster of maternally expressed genes on human chromosome 11p15.5. Disruption of imprinting leads to Beckwith-Wiedemann syndrome (BWS), an overgrowth and cancer predisposition condition. In the majority of individuals with BWS, maternal-specific methylation at KvDMR1 is absent and genes under its control are repressed. We analyzed a mouse model carrying a poly(A) truncation cassette inserted to prevent RNA transcripts from elongation through KvDMR1. Maternal inheritance of this mutation resulted in absence of DNA methylation at KvDMR1, which led to biallelic expression of Kcnq1ot1 and suppression of maternally expressed genes. This study provides further evidence that transcription is required for establishment of methylation at maternal gametic DMRs. More importantly, this mouse model recapitulates the molecular phenotypic characteristics of the most common form of BWS, including loss of methylation at KvDMR1 and biallelic repression of Cdkn1c, suggesting that deficiency of maternal transcription through KvDMR1 may be an underlying cause of some BWS cases.

Thymosin ß10 as a predictive biomarker of response to 5-fluorouracil chemotherapy in cholangiocarcinoma.

UNLABELLED:  Introduction and aim. 5-Fluorouracil (5-FU) is the most commonly used chemotherapeutic drug in the treatment of cholangiocarcinoma (CCA). Since development of drug resistance to 5-FU in CCA patients is the primary cause of treatment failure, a better understanding of the mechanism of drug resistance of this cancer is essential to improve the efficacy of 5-FU in CCA therapy. MATERIAL AND METHODS: A 5-FU resistant CCA cell line (M214-5FUR) for a comparative chemo-resistance study was established. Real time RT-PCR was used to determine gene expression levels. Cell cytotoxicity was measured by the MTT assay. Protein expression levels were detected by the immunofluorescene method. RESULTS: It was found that 5-FU resistance was associated with the overexpression of T?10 in CCA cell lines. 5-FU treatment at various concentrations induced the expressions of T?10 and ABC transporters (ABCB1, ABCG2 ABCA3) in two CCA cell lines, KKU-M055 and KKU-M214. M214-5FUR, a 5-FU-resistant cell line, exhibited a 5-FU resistant phenotype with a 16-fold extremely high expression of T?10 and ABC transporters, as compared to the parental cells, KKU-M214. siRNA targeted to T?10 significantly reduced expression of ABC transporters tested in the M214-5FUR cells (P < 0.05). CONCLUSIONS: The present novel findingsof T?10 connected with drug resistance as shown in this study provides a new insight for the therapeutic value of T?10 as a predictive biomarker of 5-FU chemoresistance. Inhibiting T?10 may be a valuable adjunct for suppression of ABC transporters and sensitizing chemotherapy treatment, especially 5-FU in CCA patients.

Suppression of thymosin ß10 increases cell migration and metastasis of cholangiocarcinoma.

BACKGROUND: Thymosin ß10 (Tß10) expression is associated with malignant phenotypes in many cancers. However, the role and mechanisms of Tß10 in liver fluke-associated cholangiocarcinoma (CCA) are not fully understood. In this study, we investigated the expression of Tß10 in CCA tumor tissues and cell lines as well as molecular mechanisms of Tß10 in tumor metastasis of CCA cell lines. METHODS: Tß10 expression was determined by real time RT-PCR or immunocytochemistry. Tß10 silence or overexpression in CCA cells was achieved using gene delivery techniques. Cell migration was assessed using modified Boyden chamber and wound healing assay. The effect of silencing Tß10 on CCA tumor metastasis was determined in nude mice. Phosphorylation of ERK1/2 and the expression of EGR1, Snail and matrix metalloproteinases (MMPs) were studied. RESULTS: Ten pairs of CCA tissues (primary and metastatic tumors) and 5 CCA cell lines were studied. With real time RT-PCR and immunostaining analysis, Tß10 was highly expressed in primary tumors of CCA; while it was relatively low in the metastatic tumors. Five CCA cell lines showed differential expression levels of Tß10. Silence of Tß10 significantly increased cell migration, invasion and wound healing of CCA cells in vitro; reversely, overexpression of Tß10 reduced cell migration compared with control cells (P<0.05). In addition, silence of Tß10 in CCA cells increased liver metastasis in a nude mouse model of CCA implantation into the spleen. Furthermore, silence of Tß10 activated ERK1/2 and increased the expression of Snail and MMPs in CCA cell lines. Ras-GTPase inhibitor, FPT inhibitor III, effectively blocked Tß10 silence-associated ERK1/2 activation, Snail expression and cell migration. CONCLUSIONS: Low expression of Tß10 is associated with metastatic phenotype of CCA in vitro and in vivo, which may be mediated by the activation of Ras, ERK1/2 and upregulation of Snail and MMPs. This study suggests a new molecular pathway of CCA pathogenesis and a novel strategy to treat or prevent CCA metastasis.

Roles and mechanisms of ß-thymosins in cell migration and cancer metastasis: an update.

ß-thymosins, including thymosin ß4 (Tß4), Tß10, and Tß15, are a family of highly conserved 5 kDa peptides. They are involved not only in normal cell migration, but also in tumor metastasis. However, the molecular mechanisms of ß-thymosins to regulate cell migration and other functions are not fully understood. Recently, this important area is under active investigation worldwide. Many new discoveries have been made from molecular biology and cell culture models as well as animal models and human diseases. This timely review provides the most updated information about functional roles and molecular mechanisms of ß-thymosins in normal tissues and disease conditions.

Advances in thymosin beta10 research: differential expression, molecular mechanisms, and clinical implications in cancer and other conditions.

Thymosin beta 10 (Tbeta10) is a member of the beta-thymosin family, which has biological activities as an actin-sequestering protein involved in cell motility. Tbeta10 may be correlated with tumor biology such as cell proliferation, apoptosis, angiogenesis, and metastasis behavior. However, the molecular mechanisms of action of Tbeta10 in cancer are largely unknown. Tbeta10 is differentially expressed in embryogenesis and neuronal development. Its expression is also increased in many inflammatory conditions and tumorigenesis. This review briefly summarizes recent advances in Tbeta10 research including differential expression, functions, mechanisms, gene regulation, and therapeutic applications in cancer, wound healing, and other diseases.