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ABSTRACT: Progesterone (Pg) is an essential steroid hormone during mammary gland development and tumorigenesis, including the maintenance of epithelial stem/progenitor cells. Pg functions through interaction with the progesterone receptors (PR) and Pg-PR signaling is thought to be mediated by key transcription factors, which are largely unidentified. In this study, we have identified the ATBF1 transcription factor as a transcriptional target of Pg-PR signaling in mammary epithelial cells. Pg treatment dramatically increased ATBF1 expression at both mRNA and protein levels in cultured cells and mammary tissues. As expected, the induction of ATBF1 was PR-dependent, as it only occurred in PR-positive but not in PR-negative cells, and pretreatment with the Pgantagonist RU-486 or RNAi-mediated knockdown of PR abolished the upregulation of ATBF1 by Pg. Promoter-reporter and ChIP assays further showed that Pg-activated PR directly binds to the ATBF1 promoter to induce its transcription. Prevention of ATBF1 induction inhibited the function of Pg in promoting progenitor cell transition, as indicated by colony formation in a Matrigel culture assay and expression of stem cell markers CD49f and CD44. These findings suggest that ATBF1 plays a crucial role in the Pg-PR signaling pathway in mammary epithelial cells.
Biochemical and Biophysical Research Communications 11/2012; · 2.48 Impact Factor
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Xiao Wu,
Zhengmao Zhu,
Weidong Li,
Xiaoying Fu,
Dan Su, Liya Fu,
Zhiqian Zhang,
Ang Luo,
Xiaodong Sun,
Li Fu,
Jin-Tang Dong
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ABSTRACT: The chromodomain helicase DNA binding protein 5 (CHD5) has recently been identified as a tumor suppressor in a mouse model. The CHD5 locus at 1p36 is deleted, and its mutation has been detected in breast cancer. We, therefore, evaluated whether CHD5 plays a role in human breast cancer.
We screened mutations in 55 tumors, determined promoter methylation in 39 tumors, measured RNA expression in 90 tumors, analyzed protein expression in 289 tumors, and correlated expression changes with clinicopathological characteristics of breast cancer. Functional effects of CHD5 on cell proliferation, invasion and tumorigenesis were also tested.
Although only one mutation was detected, CHD5 mRNA expression was significantly reduced, accompanied by frequent genomic deletion and promoter methylation, in breast cancer. The extent of methylation was significantly associated with reduced mRNA expression, and demethylating treatment restored CHD5 expression. Lower CHD5 mRNA levels correlated with lymph node metastasis (P = 0.026). CHD5 protein expression was also reduced in breast cancer, and lack of CHD5 expression significantly correlated with higher tumor stage, ER/PR-negativity, HER2 positivity, distant metastasis and worse patient survival (P ≤ 0.01). Functionally, ectopic expression of CHD5 in breast cancer cells inhibited cell proliferation and invasion in vitro and tumorigenesis in nude mice. Consistent with the inhibition of invasion, CHD5 down-regulated mesenchymal markers vimentin, N-cadherin and ZEB1 in breast cancer cells.
Down-regulation of CHD5, mediated at least in part by promoter methylation, contributes to the development and progression of human breast cancer.
Breast cancer research: BCR 05/2012; 14(3):R73. · 5.24 Impact Factor
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Dan Su,
Xiaoying Fu,
Songqing Fan,
Xiao Wu,
Xin-Xin Wang, Liya Fu,
Xue-Yuan Dong,
Jianping Jenny Ni,
Li Fu,
Zhengmao Zhu,
Jin-Tang Dong
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ABSTRACT: Whereas estrogen-estrogen receptor α (ER) signaling plays an important role in breast cancer growth, it is also necessary for the differentiation of normal breast epithelial cells. How this functional conversion occurs, however, remains unknown. Based on a genome-wide sequencing study that identified mutations in several breast cancer genes, we examined some of the genes for mutations, expression levels, and functional effects on cell proliferation and tumorigenesis. We present the data for C1orf64 or ER-related factor (ERRF) from 31 cell lines and 367 primary breast cancer tumors. Whereas mutation of ERRF was infrequent (1 of 79 or 1.3%), its expression was up-regulated in breast cancer, and the up-regulation was more common in lower-stage tumors. In addition, increased ERRF expression was significantly associated with ER and/or progesterone receptor (PR) positivity, which was still valid in human epidermal growth factor receptor 2 (HER2)-negative tumors. In ER-positive tumors, ERRF expression was inversely correlated with HER2 status. Furthermore, higher ERRF protein expression was significantly associated with better disease-free survival and overall survival, particularly in ER- and/or PR-positive and HER2-negative tumors (luminal A subtype). Functionally, knockdown of ERRF in two ER-positive breast cancer cell lines, T-47D and MDA-MB-361, suppressed cell growth in vitro and tumorigenesis in xenograft models. These results suggest that ERRF plays a role in estrogen-ER-mediated growth of breast cancer cells and could, thus, be a potential therapeutic target.
American Journal Of Pathology 03/2012; 180(3):1189-201. · 4.89 Impact Factor
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ABSTRACT: It has become increasingly clear that microRNAs (miRNAs) play important roles in tumorigenesis and metastasis. Recently, miR-203 was reported as a suppressor microRNA often silenced in different malignancies including hepatocellular carcinoma, prostate cancer, oral cancer, and hematopoietic malignancy, but little is known about its potential role in breast carcinogenesis. In this study, we found that in breast cancer, miR-203 was upregulated in primary tumors and some nonmetastatic cell lines but was significantly downregulated in metastatic cell lines including BT549, Hs578T, and MDA-MB-231, as measured by regular and real-time PCR. Downregulation of miR-203 in metastatic breast cancer cells appeared to be caused by hypermethylation of its promoter. Functionally, ectopic expression of miR-203 in BT549 and MDA-MB-231 breast cancer cell lines caused cell cycle arrest and apoptosis and inhibited cell invasion and migration in vitro. Bioinformatic analysis predicted the snail homolog 2 (SNAI2 or SLUG), a transcription factor that promotes cell invasion and tumor metastasis, as a target of miR-203, and the prediction was validated by expression analysis and luciferase reporter assay of the 3' untranslated region of SNAI2 that contains the miR-203 target sequences. These results suggest that in malignant breast cancer cells, miR-203 is epigenetically silenced, and the silencing promotes tumor cell growth and invasion at least in part by upregulating the SNAI2 transcription factor.
Genes & cancer 08/2011; 2(8):782-91.
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Xin-Xin Wang,
Zhengmao Zhu,
Dan Su,
Ting Lei,
Xiao Wu,
Yu Fan,
Xin Li,
Jing Zhao,
Liya Fu,
Jin-Tang Dong, Li Fu
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ABSTRACT: Leucine zipper putative tumor suppressor 1 is down-regulated by promoter methylation, but not frequently, in human malignancies, including breast cancer. Recent studies suggest that leucine zipper putative tumor suppressor 1 is a candidate for the metastasis modifier locus on human chromosome 8p in melanoma. In this study, we evaluated whether leucine zipper putative tumor suppressor 1 plays a role in breast cancer metastasis. We found that leucine zipper putative tumor suppressor 1 protein expression was significantly reduced or absent in a series of 340 invasive breast carcinomas compared to normal breast tissue. Lower levels of leucine zipper putative tumor suppressor 1 correlated with high histologic grade, lymph node metastasis, and poor prognosis. Functional studies demonstrated that ectopic expression of leucine zipper putative tumor suppressor 1 in the highly malignant MDA-MB-231 breast cancer cell line suppressed cell proliferation, migration, and invasion in vitro. Expression of leucine zipper putative tumor suppressor 1 in MDA-MB-231 cells also induced a series of changes that are characteristic of mesenchymal-to-epithelial transition, including phenotypic change, up-regulation of epithelial markers E-cadherin, β-catenin, and cytokeratin and down-regulation of the mesenchymal marker vimentin. Expression of leucine zipper putative tumor suppressor 1 also repressed the transcription of Slug and Snail, which both repress E-cadherin expression during epithelial-to-mesenchymal transition. These findings suggest that epithelial-to-mesenchymal transition likely inhibits breast cancer metastasis by intervening in epithelial-to-mesenchymal transition in breast cancer.
Human pathology 03/2011; 42(10):1410-9. · 3.03 Impact Factor
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ABSTRACT: The mixed-lineage leukemia 3 (MLL3) gene, which encodes an important component of a histone H3 lysine 4 methyltransferase complex named the ASC-2- and Mll3-containing complex (ASCOM), has been implicated as a tumor suppressor gene due to its frequent mutations in multiple types of human tumors as well as tumor induction upon targeted inactivation of the gene in mice. The role of MLL3 in breast cancer, however, remains unknown. In this study, we sequenced all 59 exons of MLL3 (14.7 Kb coding sequence) in 38 breast cancers from Chinese women, and found three somatic mutations in two of the cases, including one frameshift mutation (c.2687 ins A) that truncates the majority of the MLL3 protein, and two synonymous mutations. In addition to 24 known single nucleotide polymorphisms (SNPs), 5 novel SNPs were also detected in the 38 women; and interestingly, all the 5 novel SNPs alter amino acid sequences of MLL3 thus could have functional consequences. We also examined the expression of MLL3 mRNA in 30 breast tumors and their matched normal breast tissues. While no associations were found between expression change and clinicopathologic parameters, 40% of the samples showed reduced expression in cancer tissues. These results suggest that mutation of MLL3 plays a role in the development of breast cancer.
Pathology & Oncology Research 11/2010; 17(2):429-33. · 1.37 Impact Factor
