Michelle Ky Siu

Stem cell transcription factor NANOG controls cell migration and invasion via dysregulation of E-cadherin and FoxJ1 and contributes to adverse clinical outcome in ovarian cancers

Ovarian cancer is the most lethal of all gynecological malignancies, and the identification of novel prognostic and therapeutic targets for ovarian cancer is crucial. It is believed that only a small subset of cancer cells are endowed with stem cell properties, which are responsible for tumor growth, metastatic progression and recurrence. NANOG is one of the key transcription factors essential for maintaining self-renewal and pluripotency in stem cells. This study investigated the role of NANOG in ovarian carcinogenesis and showed overexpression of NANOG mRNA and protein in the nucleus of ovarian cancers compared with benign ovarian lesions. Increased nuclear NANOG expression was significantly associated with high-grade cancers, serous histological subtypes, reduced chemosensitivity, and poor overall and disease-free survival. Further analysis showed NANOG is an independent prognostic factor for overall and disease-free survival. Moreover, NANOG was highly expressed in ovarian cancer cell lines with metastasis-associated property and in clinical samples of metastatic foci. Stable knockdown of NANOG impeded ovarian cancer cell proliferation, migration and invasion, which was accompanied by an increase in mRNA expression of E-cadherin, caveolin-1, FOXO1, FOXO3a, FOXJ1 and FOXB1. Conversely, ectopic NANOG overexpression enhanced ovarian cancer cell migration and invasion along with decreased E-cadherin, caveolin-1, FOXO1, FOXO3a, FOXJ1 and FOXB1 mRNA expression. Importantly, we found Nanog-mediated cell migration and invasion involved its regulation of E-cadherin and FOXJ1. This is the first report revealing the association between NANOG expression and clinical outcome of patients with ovarian cancers, suggesting NANOG to be a potential prognostic marker and therapeutic molecular target in ovarian cancer.

Aberrant activation of hedgehog signaling pathway contributes to endometrial carcinogenesis through β -catenin

The hedgehog and Wnt signaling pathways play important roles in human cancers with possible interaction. This study aimed at analysis and correlation of the expression of Gli1, a transcriptional factor and target gene of hedgehog signaling pathway, with clinicopathological parameters and expression of β-catenin, an important member of the Wnt pathway, in normal, hyperplastic and malignant endometrium. Immunohistochemical study on 15 normal endometrium, 14 simple and complex hyperplasia without atypia, 37 atypical complex hyperplasia and 80 endometrial cancers showed significant Gli1 overexpression and β-catenin nuclear immunoreactivity in endometrial cancers and atypical endometrial hyperplasia when compared with normal endometrium (P<0.05). Overexpression of Gli1 in endometrial cancers correlated with well-differentiated histological grade (P<0.001), non-myometrial invasion (P=0.004) and superficial myometrial invasion (P=0.041). β-Catenin nuclear immunoreactivity was also associated with well-differentiated histology (P=0.013). Gli1 overexpression positively correlated with β-catenin nuclear immunoreactivity in atypical complex hyperplasia (P=0.013) and endometrial carcinoma (P=0.017). Similar Gli1 and β-catenin protein expression pattern was observed in normal and endometrial cancer cell lines by western blotting. We further showed a complex formation between Gli1 and β-catenin protein in endometrial cancer cell lines in an immunoprecipitation study. Ectopic overexpression of Gli1 into endometrial cancer cells led to reduced expression of β-catenin in cell cytoplasm and increased expression of β-catenin in the nuclei. In summary, overexpression of Gli1 was an early event in endometrial carcinogenesis. Aberrant activation of hedgehog pathway may play important roles in endometrial cancer through β-catenin nuclear accumulation.

p63 expression in ovarian tumours: a marker for Brenner tumours but not transitional cell carcinomas.

Aims:  To investigate p63 expression in ovarian neoplasms.

Activated Stat3 expression in gestational trophoblastic disease: correlation with clinicopathological parameters and apoptotic indices

Aims:  To assess the expression profile of the activated form of signal transducer and activator of transcription (Stat)3 in gestational trophoblastic disease (GTD) and correlate the findings with clinicopathological parameters.

Overexpression of prostate stem cell antigen is associated with gestational trophoblastic neoplasia

Aims:  Hydatidiform mole (HM) is the most common type of gestational trophoblastic disease. A proportion of patients with HM develop gestational trophoblastic neoplasia (GTN) requiring chemotherapy. The aim was to identify differentially expressed genes that are associated with development of GTN.

TrkB as a therapeutic target for ovarian cancer.

Background: In many countries, ovarian cancer is the most lethal gynecological malignancy. Its poor prognosis is mainly due to the late stage of disease with metastasis at presentation. The significant failure rate of chemotherapy in patients with advanced stage disease is also a main concern. As such, developing novel therapeutic targets is essential to improve long-term survival. Overexpression of Tropomyosin-related kinase B (TrkB), a tyrosine kinase receptor, has been documented in ovarian cancer and is found to be correlated with poor prognosis. Objective/methods: We discuss the functional roles and the related downstream signaling pathways of TrkB and its ligand brain-derived neurotrophic factor (BDNF) in ovarian cancer. The possible crosstalk between TrkB/BDNF and other putative molecular targets in ovarian cancer is also discussed. Results/conclusions: All these latest findings shed light on the application of TrkB as a therapeutic target for ovarian cancer.

Abstract LB-270: Hexokinase II (HK2) regulates stemness of ovarian cancer cells

Cancer stem cells (CSCs) constitute a small proportion of tumor cells and can drive tumor growth, metastasis and recurrence. Identification of CSCs in ovarian cancer has been reported. However, the mechanisms regulating ovarian cancer CSCs remain unknown. High lactate production and low glucose oxidation, despite oxygen availability, termed as the Warburg effect, are commonly found in cancers. Hexokinase 2 (HK2) converts glucose to glucose-6-phosphate, the first committed step in the Warburg effect. HK2 regulates tumorigenesis in different cancers. Yet, roles of HK2 and its underline mechanisms in ovarian cancer remain to be explored. In this study, we investigate the clinical significance, effects and mechanisms of HK2 on cell metastasis and CSCs regulation in ovarian cancer. HK2 was found to be up-regulated in ovarian cancer patients by immunohistochemistry when compared with benign ovarian cystadenomas. Significantly higher HK2 immunoreactivity was detected in metastatic foci than their corresponding primary tumors and associated with shorter disease-free survival. Decreased lactate production, impaired cell migration and invasion were detected in HK2 knockdown A2780CP cells using lactate assay, Transwell migration and invasion assays, respectively. Oppositely, ectopic expression of HK2 increased lactate production, cell migration and invasion in SKOV3 cells. We also found ectopic expression of HK2 in SKOV3 cells promoted anchorage-independent growth by soft agar assay. Then we further investigated the effect of HK2 on CSC load of ovarian cancer. Stable knockdown of HK2 in OVCAR3 cells led to impaired capacity to grow as multi-cellular spheroids in stem-condition culture system by sphere formation. Knockdown of HK2 in OVCAR3 cells down-regulated CD117 as measured by flow cytometry, which was accompanied by decreased mRNA/protein expression of Nanog, Bmi-1 and Klf-4, genes related to ovarian CSCs. Inversely, ectopic expression of HK2 in SKOV-3 cells promoted spheroids growth and increased CD117 proportion, which was accompanied by increased Nanog, Bmi-1 and Klf-4 mRNA/protein expression. Our data suggested that HK2 was associated with ovarian cancer progression, metastasis and stemness. HK2 could be a novel prognostic marker and potential therapeutic molecular target in ovarian cancer. Citation Format: Yuxin JIANG, Michelle KY Siu, Jingjing Wang, Thomas HY Leung, Annie NY Cheung, Hextan YS Ngan, Karen KL Chan. Hexokinase II (HK2) regulates stemness of ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-270. doi:10.1158/1538-7445.AM2017-LB-270

Abstract LB-269: PFKP/PFKFB3 modulate metabolic switch and chemoresistance to cisplatin in ovarian cancer

Background: Late diagnosis and occurrence of chemoresistance contribute ovarian cancer the most malignant gynaecological cancer. High lactate generation and low glucose oxidation, regardless of oxygen availability, termed as the Warburg effect, are commonly found in cancers. Phosphofructokinase-1 (PFK-1) irreversibly converts fructose-6-phosphate to fructose-1,6-bisphosphate, the first committed step in the Warburg effect. PFK1 can be activated by fructose-2,6-bisphosphate (F2,6BP), which in turn is generated and degraded by 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatases (PFKFB). The platelet isoform of PFK (PFKP) and inducible PFKFB3 isoform modulate glycolysis and contribute to tumorigenesis in other human cancers, the precise mechanisms have yet to be elucidated. Moreover, PFKP and PFKFB3 in ovarian cancer remain to be characterized. We hypothesize that PFKP, which is regulated by mi106a-5p, along with PFKFB3 modulate cancer metabolic switch and chemoresistance to cisplatin in ovarian cancer. Methods: Expression of PFKP and PFKFB3 in ovarian cancer cell lines was investigated by qPCR and immunoblotting. Expression of PFKP in 123 ovarian cancer tissue samples was evaluated by immunohistochemistry. The correlation between PFKP and clinicopathological parameters was analyzed. Ectopic expression or knockdown of PFKP/PFKFB3/miR106a-5p and treatment with 3PO (a PFKFB3 inhibitor), followed by lactate assay and TUNEL assay or annexin V/propidium iodide staining after treatment with cisplatin were performed in ovarian cancer cell lines to detect the effects on cancer metabolic switch and chemoresistance to cisplatin respectively. Additionally, the related apoptosis signaling pathway was explored by RT 2 profiler PCR array and immuoblotting. Results: We found up-regulation of PFKP in ovarian cancer cell lines and patient samples with significantly higher PFKP found in chemoresistant than chemosensitive cell lines and clinical samples. Higher PFKP was correlated to shorter overall and disease-free survival. Higher PFKFB3 was also detected in chemoresistant than chemosensitive cell lines. Functionally, knockdown of PFKP/PFKFB3 in ovarian cancer resistant cells decreased lactate level, sensitized cells to cisplatin treatment, which was accompanied by increased cleavage of PARP. 3PO also reduced lactate level and sensitized A2780CP cells to cisplatin treatment, along with altered c-IAP1, c-IAP2, survivin and CD70 expression, and increased cleavage of caspases-9/7 and PARP. Ectopic expression of miR106a-5p decreased PFKP expression, reduced lactate level and sensitized A2780CP cells to cisplatin treatment. Conclusion: Our findings suggest that PFKP/PFKFB3 may overcome chemoresistance in ovarian cancer cells through apoptosis related pathway. Results also show the potential use of PFKFB3 inhibitor as therapeutic targets either alone or in combination with cisplatin and PFKP as a novel prognostic marker for ovarian cancer. Citation Format: Jingjing Wang, Michelle KY Siu, Yuxin Jiang, Thomas HY Leung, Hextan YS NGAN, Annie NY Cheung, Karen KL Chan. PFKP/PFKFB3 modulate metabolic switch and chemoresistance to cisplatin in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr LB-269. doi:10.1158/1538-7445.AM2017-LB-269

Abstract 2107: Downregulation of ASPP2 in choriocarcinoma contributes to increased migratory potential through Src activation

Poster Session 7 - Signaling Pathways Involved in Oncogenesis and Tumor Suppression: abstract no. 2107

Abstract LB-15: Overexpression of Pak1 and Pak4 contributes to endometrial carcinogenesis

Late-Breaking Poster Session - Late-Breaking Research: Cellular and Molecular Biology 1: abstract no. LB-15