Chia-Yi Hsu

Phthalates induce proliferation and invasiveness of estrogen receptor-negative breast cancer through the AhR/HDAC6/c-Myc signaling pathway

The environmentally present group of chemical phthalates, or phthalate esters, has been recognized as a rising threat to public health, including cancer. While most studies have addressed the estrogenic effects of phthalates in malignancies of the breast and the prostate, little is known about their role in the etiology of hormone‐independent cancer. Here we show that treatments with the phthalates n‐butyl benzyl phthalate (BBP) and dibutyl phthalate (DBP) at 1 μM induced proliferation (BBP, 3.2‐fold; DBP, 3.2‐fold), migration (BBP, 2.6‐fold; DBP, 2.6‐fold), invasion (BBP, 2.7‐fold; DBP, 3.1‐fold), and tumor formation (EC50: BBP, 0.12 μM; DBP, 0.22 μM) in estrogen receptor (ER)‐negative breast cancer cells (MDA‐MB‐231). We further demonstrate that phthalates stimulated the cell surface aryl hydrocarbon receptor (AhR) and triggered the downstream cyclic AMP (cAMP)‐PKA‐CREB1 signaling cascade. The pathway led to increased expression of HDAC6, which facilitated nuclear assembly of the β‐catenin‐LEF1/TCF4 transcriptional complex and transactivation of the c‐Myc oncogene. This nongenomic pathway emanated from the phthalateinduced AhR promoted tumorigenesis of ER‐negative breast cancer. Collectively, our findings revealed a novel oncogenic mechanism of phthalates in breast cancer independent from their estrogenic activities.—Hsieh, T.‐H., Tsai, C.‐F., Hsu, C.‐Y., Kuo, P.‐L., Lee, J.‐N., Chai, C.‐Y., Wang, S.‐C., Tsai, E.‐M. Phthalates induce proliferation and invasiveness of estrogen receptor‐negative breast cancer through the AhR/HDAC6/c‐Myc signaling pathway. FASEB J. 26, 778–787 (2012). www.fasebj.org

miRNA-199a-5p regulates VEGFA in endometrial mesenchymal stem cells and contributes to the pathogenesis of endometriosis.

It is believed that endometrial miRNAs contribute to the aetiology of endometriosis in stem cells; however, the mechanisms remain unclear. Here we collected serum samples from patients with or without endometriosis and characterized the miRNA expression profiles of these two groups. MicroRNA‐199a‐5p (miR‐199a‐5p) was dramatically down‐regulated in patients with endometriosis compared with control patients. In addition, we found that the tumour suppressor gene, SMAD4, could elevate miR‐199a‐5p expression in ectopic endometrial mesenchymal stem cells. Up‐regulation of miR‐199a‐5p suppressed cell proliferation, motility and angiogenesis of these ectopic stem cells by targeting the 3′ untranslated region of VEGFA. Furthermore, we established an animal model of endometriosis and found that miR‐199a‐5p could decrease the size of endometriotic lesions in vivo. Taken together, this newly identified miR‐199a‐5p module provides a new avenue to the understanding of the processes of endometriosis development, especially proliferation, motility and angiogenesis, and may facilitate the development of potential therapeutics against endometriosis. Copyright

n-Butyl Benzyl Phthalate Promotes Breast Cancer Progression by Inducing Expression of Lymphoid Enhancer Factor 1

Environmental hormones play important roles in regulating the expression of genes involved in cell proliferation, drug resistance, and breast cancer risk; however, their precise role in human breast cancer cells during cancer progression remains unclear. To elucidate the effect of the most widely used industrial phthalate, n-butyl benzyl phthalate (BBP), on cancer progression, we evaluated the results of BBP treatment using a whole human genome cDNA microarray and MetaCore software and selected candidate genes whose expression was changed by more than ten-fold by BBP compared with controls to analyze the signaling pathways in human breast cancer initiating cells (R2d). A total of 473 genes were upregulated, and 468 were downregulated. Most of these genes are involved in proliferation, epithelial-mesenchymal transition, and angiogenesis signaling. BBP induced the viability, invasion and migration, and tube formation in vitro, and Matrigel plug angiogenesis in vivo of R2d and MCF-7. Furthermore, the viability and invasion and migration of these cell lines following BBP treatment was reduced by transfection with a small interfering RNA targeting the mRNA for lymphoid enhancer-binding factor 1; notably, the altered expression of this gene consistently differentiated tumors expressing genes involved in proliferation, epithelial-mesenchymal transition, and angiogenesis. These findings contribute to our understanding of the molecular impact of the environmental hormone BBP and suggest possible strategies for preventing and treating human breast cancer.

Phthalates Stimulate the Epithelial to Mesenchymal TransitionThrough an HDAC6-Dependent Mechanism in Human BreastEpithelial Stem Cells

Phthalates are environmental hormone-like molecules that are associated with breast cancer risk and are involved in metastasis, a process that requires the epithelial-mesenchymal transition (EMT). However, few studies have addressed the potential effects of phthalates on stem cells. Here we tested the hypothesis that phthalates such as butyl benzyl phthalate and di-n-butyl phthalate induce EMT in R2d cells, a stem cell-derived human breast epithelial cell line that is responsive to estradiol for tumor development. We observed that phthalates induced EMT as evidenced by morphological changes concomitant with increased expression of mesenchymal markers and decreased expression of epithelial markers. Molecular mechanism studies revealed that histone deacetylase 6 (HDAC6) is required for phthalate-induced cell migration and invasion during EMT in vitro and metastasis into the lungs of nude mice. We also constructed a series of mutant HDAC6 promoter fragments and found that the transcription factor AP-2a plays a novel role in regulating the HDAC6 promoter. Furthermore, phthalates stimulated estrogen receptors and triggered the downstream EGFR-PKA signaling cascade, leading to increased expression of AP-2a in the nucleus. We also observed that phthalates increased expression of the PP1/HDAC6 complex and caused Akt activation and GSK3β inactivation, leading to transcriptional activation of vimentin through the β-catenin-TCF-4/LEF1 pathway. Understanding the signaling cascades of phthalates that activate EMT through HDAC6 in breast epithelial stem cells provides the identification of novel therapeutic target for human breast cancer.

Possible mechanism of phthalates-induced tumorigenesis

Phthalates—substances used in the manufacture of plastics—are considered as possible human carcinogens and tumor‐promoting agents. The worldwide annual production of plastics surpassed 300 million tons in 2010. Plastics are an indispensable material in modern society, and many products manufactured from plastics are a boon to public health; however, plastics also pose health risks. Animal studies have indicated that phthalates are carcinogenic, but human epidemiological data confirming this carcinogenicity in humans are limited. The activation of peroxisome proliferator‐activated receptor α (PPARα), which has been observed in rodent carcinogenesis, has not been observed in humans. Here, we review the hypothesis that the aryl hydrocarbon receptor (AhR) and its downstream signaling cascade promote phthalate‐induced tumorigenesis.

A novel cell-penetrating peptide suppresses breast tumorigenesis by inhibiting β-catenin/LEF-1 signaling

The inhibition of β-catenin/LEF-1 signaling is an emerging strategy in cancer therapy. However, clinical targeted treatment of the β-catenin/LEF-1 complex remains relatively ineffective. Therefore, development of specific molecular targets is a key approach for identifying new cancer therapeutics. Thus, we attempted to synthesize a peptide (TAT-NLS-BLBD-6) that could interfere with the interaction of β-catenin and LEF-1 at nuclei in human breast cancer cells. TAT-NLS-BLBD-6 directly interacted with β-catenin and inhibited breast cancer cell growth, invasion, migration, and colony formation as well as increased arrest of sub-G1 phase and apoptosis; it also suppressed breast tumor growth in nude mouse and zebrafish xenotransplantation models, showed no signs of toxicity, and did not affect body weight. Furthermore, the human global gene expression profiles and Ingenuity Pathway Analysis software showed that the TAT-NLS-BLBD-6 downstream target genes were associated with the HER-2 and IL-9 signaling pathways. TAT-NLS-BLBD-6 commonly down-regulated 27 candidate genes in MCF-7 and MDA-MB-231 cells, which are concurrent with Wnt downstream target genes in human breast cancer. Our study suggests that TAT-NLS-BLBD-6 is a promising drug candidate for the development of effective therapeutics specific for Wnt/β-catenin signaling inhibition.

KRAS mutation coupled with p53 loss is sufficient to induce ovarian carcinosarcomas in mice

Ovarian carcinosarcoma cancer is the most lethal form of gynecological malignancy, but the pathogenesis and biological function for this ovarian cancer remain unknown. We establishment the transgenic mouse model of K‐rasG12Dp53loxP/loxP and found that K‐ras mutation and p53 deletion within the ovarian surface epithelium gave rise to ovarian lesions with a hyperproliferation and endometrioid glandular morphology. Furthermore, double mutant ovaries formed ovarian carcinosarcomas that were high grade and poorly differentiated. Induction was widely metastatic and spread to abdominal organs including liver, spleen, and kidney at 4 wk. We also confirmed the role of K‐rasG12D in ovarian cancer cell lines MCAS and PA‐1 and showed that K‐rasG12D overexpression strongly induced cell proliferation, migration, and invasion. The ovarian cancer model we developed recapitulates the specific tumor histomorphology and the probable mechanism of malignant transformation in endometriosis.

Synthetic Steroid Hormones Regulated Cell Proliferation Through MicroRNA-34a-5p in Human Ovarian Endometrioma

ABSTRACT Endometriosis is the hormone-dependent product of endometrial tissue found outside the uterus. Recently, micro-RNAs (miRNAs) were shown to play a role in endometriotic lesion development. However, the mechanism of steroid hormones responsible for miRNA remains obscure. In the present study, we assayed for the effects of synthetic steroid hormones (danazol, progesterone, and medroxyprogesterone acetate [MPA]) on miRNAs in endometriosis. We used a global miRNA expression profile microarray to evaluate miRNA expression in endometrial mesenchymal stem cells (EN-MSCs) of ovarian endometrioma following treatment with 1 μM danazol, progesterone, or MPA. Furthermore, we selected candidate miRNAs whose expression changed more than fivefold and compared the effects of danazol, progesterone, and MPA treatments and also compared those results with controls in EN-MSCs. Among those with a fivefold change, we found 13 ectopically upregulated miRNAs in EN-MSCs. To understand the function of these 13 miRNAs, we subjected their sequences to Ingenuity Pathway Analysis. According to both the etiology and pathogenesis of endometriosis, we found that miR-199a-5p and miR-34a-5p showed specific association with the disease, including molecular and cellular functions. Steroid hormone treatment elevated the levels of miR-199a-5p and miR-34a-5p. An inhibitor of miR-34a-5p also reduced the synthetic steroid hormones effects on cell proliferation. In vivo data revealed that miRNA levels in endometriotic lesions correlated with findings following in vitro synthetic hormone treatment. Our data show the effects of synthetic steroid hormones on miRNA regulation. These findings contribute to our understanding of the molecular impact of the synthetic steroid hormones and suggest a potential mechanism for endometriosis treatment.

Benzyl butyl phthalate decreases myogenic differentiation of endometrial mesenchymal stem/stromal cells through miR-137-mediated regulation of PITX2

Phthalate, an environmental toxin, has been considered as an endocrine-disrupting chemical. Growing evidence has demonstrated links between endocrine-disrupting chemicals, tissue development, and reproductive physiology, but the mechanisms of gene expression regulation by environmental factors that affect cell differentiation are unclear. Herein, we investigated the effects of butyl benzyl phthalate (BBP) on human endometrial mesenchymal stem/stromal cell (EN-MSC) differentiation and identified a novel signaling pathway. Differentiation of endometrial mesenchymal stem/stromal cells decreased after administration of BBP. We analyzed BBP regulation of gene expression in EN-MSC using cDNA microarrays and Ingenuity Pathway Analysis software to identify affected target genes and their biological functions. PITX2 emerged as a common gene hit from separate screens targeting skeletal and muscular disorders, cell morphology, and tissue development. BBP decreased transcription of PITX2 and elevated expression of the microRNA miR-137, the predicted upstream negative regulator of PITX2. These data indicated that BBP affects PITX2 expression through miR-137 targeting of the 3′ untranslated region of PITX2 mRNA. PITX2 down-regulation also decreased MyoD transcript levels in EN-MSC. Our results demonstrate that BBP decreases EN-MSC myogenic differentiation through up-regulation of miR-137, contribute to our understanding of EN-MSC differentiation, and underline the hazardous potential of environmental hormones.