Kuei Yang Hsiao

Histone H4 deacetylation facilitates 53BP1 DNA damage signaling and double-strand break repair

53BP1 and other DNA damage response (DDR) proteins form foci at double-strand breaks (DSBs) which promote their repair by nonhomologous end joining (NHEJ). Focal accumulation of 53BP1 depends on the specific interaction of its tandem Tudor domain with dimethylated lysine 20 in histone H4 (H4K20me2). How 53BP1 foci dynamics are regulated is unclear since H4K20me2 is highly abundant, established largely in the absence of DNA damage, and uncertainty exists about the roles of candidate H4K20 methyltransferases in 53BP1 foci formation. Here, we show that 53BP1 foci assemble primarily on H4K20me2 established prior to DNA damage by the SETD8 and SUV420 methyltransferases rather than de novo H4K20 methylation mediated by MMSET/WHSC1. Moreover, we define a novel role for H4K16 acetylation in regulating 53BP1 foci dynamics. Concurrent acetylation at H4K16 antagonizes 53BP1 binding to extant H4K20me2 until DSBs elicit transient, localized H4 deacetylation that facilitates 53BP1 foci formation and NHEJ, and is associated with global repression of gene transcription. Our findings demonstrate that rapid induction of H4 deacetylation by DSBs affects multiple aspects of the DDR, and also suggest that antagonism of 53BP1 binding to H4K20me2 by H4K16 hyperacetylation may contribute to the efficacy of histone deacetylase inhibitors for cancer therapy.

Noncoding effects of circular RNA CCDC66 promote colon cancer growth and metastasis

Circular RNA (circRNA) is a class of noncoding RNA whose functions remain mostly unknown. Recent studies indicate circRNA may be involved in disease pathogenesis, but direct evidence is scarce. Here, we characterize the functional role of a novel circRNA, circCCDC66, in colorectal cancer. RNA-Seq data from matched normal and tumor colon tissue samples identified numerous circRNAs specifically elevated in cancer cells, several of which were verified by quantitative RT-PCR. CircCCDC66 expression was elevated in polyps and colon cancer and was associated with poor prognosis. Gain-of-function and loss-of-function studies in colorectal cancer cell lines demonstrated that circCCDC66 controlled multiple pathological processes, including cell proliferation, migration, invasion, and anchorage-independent growth. In-depth characterization revealed that circCCDC66 exerts its function via regulation of a subset of oncogenes, and knockdown of circCCDC66 inhibited tumor growth and cancer invasion in xenograft and orthotopic mouse models, respectively. Taken together, these findings highlight a novel oncogenic function of circRNA in cancer progression and metastasis. Cancer Res; 77(9); 2339-50. ©2017 AACR.

Three‐dimensional power Doppler imaging of ovarian stromal blood flow in women with endometriosis undergoing in vitro fertilization

The aims of this retrospective study were to investigate whether the quantification of ovarian stromal blood flow and/or leptin concentration are predictive of in vitro fertilization (IVF) outcomes in women after laparoscopic ovarian cystectomy for large endometriomas.

Upregulation of Steroidogenic Enzymes and Ovarian 17β-Estradiol in Human Granulosa-Lutein Cells by Cordyceps sinensis Mycelium

Abstract There is increasing evidence that 17β-estradiol (E2) directly influences the quality of maturing oocytes and thus the outcome of assisted reproduction treatment. Although Cordyceps sinensis (CS) mycelium, a Chinese herbal medicine, is believed to enhance libido and fertility in both sexes, the mechanism of its effect in women has not been determined. The aim of the present study was to evaluate the effects of CS on steroidogenic enzyme expression and E2 biosynthesis in human granulosa-lutein cells (GLC). We found that CS induced E2 production by GLC in a dose- and time-dependent manner and that a 3-h treatment with CS induced increased levels of mRNAs coding for the P450 side chain cleavage enzyme (P450scc), 3β-hydroxysteroid dehydrogenase (3β-HSD), and aromatase. Western blot analysis demonstrated that, after treatment with CS for 3 h, protein levels of steroidogenic acute regulatory protein (StAR) and aromatase were upregulated while P450scc and 3β-HSD levels showed no substantial change. New protein synthesis was required for CS-induced E2 production because it was abrogated by cycloheximide pretreatment. Addition of 22(R)-hydroxycholesterol, thus bypassing the need for StAR protein, did not induce as much E2 production as CS treatment, indicating that upregulation of StAR protein was not the only factor contributing to CS-induced steroidogenesis. Cotreatment of GLCs with CS and aminoglutethimide, an aromatase inhibitor, completely abolished CS-induced E2 production. In conclusion, treatment of GLCs with CS results in increased E2 production due, at least in part, to increased StAR and aromatase expression. These data may help in the development of treatment regimens to improve the success rate of in vitro fertilization.

Inhibition of dual specificity phosphatase-2 by hypoxia promotes interleukin-8-mediated angiogenesis in endometriosis

STUDY QUESTION How does hypoxia-mediated down-regulation of dual specificity phosphatase-2 (DUSP2) promote endometriotic lesion development? SUMMARY ANSWER Inhibition of DUSP2 by hypoxia enhances endometriotic lesion growth via promoting interleukin-8 (IL-8)-dependent angiogenesis. WHAT IS KNOWN ALREADY Angiogenesis is a prerequisite for the development of endometriosis. DUSP2 is down-regulated in endometriotic stromal cells in a hypoxia inducible factor-1α-dependent manner. Down-regulation of DUSP2 contributes to the pathological process of endometriosis. STUDY DESIGN, SIZE, DURATION A laboratory study recruiting 20 patients of reproductive age with endometriosis and normal menstrual cycles, and an autoimplant-induced mouse model of endometriosis using 13 mice in a 28-day treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS IL-8 mRNA levels were assayed in endometrial stromal cells maintained in normoxic or hypoxic (1% O2) conditions, with or without DUSP2 knockdown. Promoter activity and chromatin immunoprecipitation (ChIP) assays were conducted to characterize the regulation of IL-8 by DUSP2. Conditioned media from cells maintained in normoxic or hypoxic conditions, and cells with/without DUSP2 knockdown were collected to investigate the angiogenic capacity using an in vitro tube formation assay. Reparixin, an IL-8 receptor blocker, was administered to investigate the role of IL-8 in hypoxia-mediated angiogenesis and the development of endometriotic-like lesions in an autotransplanted mouse model. MAIN RESULTS AND THE ROLE OF CHANCE IL-8 mRNA was increased by both hypoxia and DUSP2 knockdown in endometrial stromal cells in an extracellular signal-regulated protein kinase-dependent manner (P < 0.05 versus control). Promoter activity and ChIP assays demonstrated that expression of IL-8 was regulated by CCAAT/enhancer binding protein α (P < 0.05 versus control). Furthermore, conditioned media collected from hypoxia-exposed or DUSP2 knockdown endometrial stromal cells promoted tube formation, which was abolished by co-treatment with reparixin (P < 0.05 versus control). Results from the autotransplanted mouse model demonstrated that number of blood vessels and size of endometriotic-like lesions were markedly reduced in recipient mice treated with reparixin (P < 0.05 versus control). LIMITATIONS, REASONS FOR CAUTION This study was conducted in primary human cell cultures and a mouse model, therefore may not fully reflect the situation in vivo. WIDER IMPLICATIONS OF THE FINDINGS This is the first study to highlight the potential application of an IL-8 receptor blocker as a therapeutic target to treat endometriosis. This study demonstrates IL-8 as a key angiogenic factor regulated by hypoxia/DUSP2, which suggests an alternative mechanism through which hypoxia may promote angiogenesis. STUDY FUNDING/COMPETING INTERESTS This study was funded by the National Science Council of Taiwan (NSC101-2314-B-006-043-MY2). The author declares that there is no conflict of interest.

Hypoxia-inhibited dual-specificity phosphatase-2 expression in endometriotic cells regulates cyclooxygenase-2 expression.

Endometriosis is one of the most common gynaecological diseases that significantly reduces the life qualify of affected women and their families. Aberrant expression of cyclooxygenase‐2 (COX‐2), and thus over‐production of prostaglandin E2 (PGE2) has been shown to play critical roles in the development of this disease. However, the mechanism responsible for COX‐2 over‐expression remains obscure. Here, we provide evidence for what we believe is a novel mechanism in regulating COX‐2 expression in endometriotic stromal cells. Dual‐specificity phosphatase‐2 (DUSP2), a nuclear phosphatase that inactivates mitogen‐activated protein kinase (MAPK), is markedly down‐regulated in stromal cells of ectopic endometriotic tissues, which results in prolonged activation of extracellular signal‐regulated kinase (ERK) and p38 MAPK and increased COX‐2 expression. Expression of DUSP2 is inhibited by hypoxia inducible factor‐1α (HIF‐1α) at the transcriptional level. Treatment of normal endometrial stromal cells with hypoxia, or chemicals that cause HIF‐1α accumulation, results in DUSP2 down‐regulation, prolonged ERK phosphorylation and COX‐2 over‐expression. In contrast, forced expression of DUSP2 under hypoxia abolishes HIF‐1α‐induced ERK phosphorylation and COX‐2 expression. Furthermore, suppression of DUSP2 by HIF‐1α in eutopic endometrial stromal cells increases sensitivity of cox‐2 gene to interleukin‐1β stimulation, a phenomenon resembling endometriotic stromal cell characteristics. Taken together, these data suggest that DUSP2 is an important molecule in endometrial physiology and that hypoxia‐inhibited DUSP2 expression is a critical factor for the development of endometriosis. Copyright

Circular RNA – New member of noncoding RNA with novel functions

A growing body of evidence indicates that circular RNAs are not simply a side product of splicing but a new class of noncoding RNAs in higher eukaryotes. The progression for the studies of circular RNAs is accelerated by combination of several advanced technologies such as next generation sequencing, gene silencing (small interfering RNAs) and editing (CRISPR/Cas9). More and more studies showed that dysregulated expression of circular RNAs plays critical roles during the development of several human diseases. Herein, we review the current advance of circular RNAs for their biosynthesis, molecular functions, and implications in human diseases. Impact statement The accumulating evidence indicate that circular RNA (circRNA) is a novel class of noncoding RNA with diverse molecular functions. Our review summarizes the current hypotheses for the models of circRNA biosynthesis including the direct interaction between upstream and downstream introns and lariat-driven circularization. In addition, molecular functions such as a decoy of microRNA (miRNA) termed miRNA sponge, transcriptional regulator, and protein-like modulator are also discussed. Finally, we reviewed the potential roles of circRNAs in neural system, cardiovascular system as well as cancers. These should provide insightful information for studying the regulation and functions of circRNA in other model of human diseases.

Hypoxia-inhibited DUSP2 expression promotes IL-6/STAT3 signaling in endometriosis

How does hypoxia‐mediated downregulation of dual‐specificity phosphatase‐2 (DUSP2) promote the development of endometriotic lesions?

Pathological functions of hypoxia in endometriosis.

Endometriosis is one of the most common gynecological diseases that significantly reduce the life quality of affected women. Research results from the past decade clearly demonstrated that aberrant production of estrogen and cyclooxygenase-2-derived prostaglandin E2 play indispensable roles in the pathogenesis of this disease. However, the etiology of endometriosis remains obscure. Recent evidence reveals a new facet of endometriotic pathogenesis by showing that hypoxia induces the expression of many important downstream genes to regulate the implantation, survival, and maintenance of ectopic endometriotic lesions. These new findings shed lights on future investigations of delineating the etiology of endometriosis and designing new therapeutic strategy for endometriosis.

Loss of dual‐specificity phosphatase‐2 promotes angiogenesis and metastasis via up‐regulation of interleukin‐8 in colon cancer

Dual‐specificity phosphatase 2 (DUSP2) is a negative regulator of mitogen‐activated protein kinases. Our previous study showed that DUSP2 expression is down‐regulated in many human cancers and loss of DUSP2 promotes cancer progression; however, the underlying mechanism remains largely uncharacterized. Herein, we found that loss of DUSP2 induces angiogenesis, while forced expression of DUSP2 inhibits microvessel formation in xenografted mouse tumours. Genome‐wide screening of expression profiles, and meta‐analysis of clinical data, identified that the level of interleukin‐8 (IL‐8) correlated negatively with that of DUSP2, suggesting that it may be a downstream target of DUSP2. Molecular characterization revealed that DUSP2 inversely regulates IL‐8 expression, mediated by ERK1/2 and C/EBPα‐dependent transcriptional regulation. Further study showed that hypoxia‐induced IL‐8 expression in cancer cells is also mediated via down‐regulation of DUSP2. Treatment with the IL‐8 receptor inhibitor reparixin or knockdown of IL‐8 in cancer cells abolished angiogenesis induced by loss of DUSP2. Functionally, knockdown of DUSP2 enhanced tumour growth and metastasis, which were abolished by treatment with reparixin or knockdown of IL‐8 in an orthotopic mouse model. Taken together, our results demonstrate that hypoxia inhibits DUSP2 expression in colon cancer, leading to up‐regulation of IL‐8, which facilitates angiogenesis and tumour metastasis. Our findings suggest that blocking hypoxia–DUSP2–IL‐8 signalling may be a plausible approach for therapeutic intervention in cancer. Copyright