Zongyuan Yang

miR-222 is upregulated in epithelial ovarian cancer and promotes cell proliferation by downregulating P27(kip1.)

Epithelial ovarian cancer (EOC) is the leading cause of female reproductive system cancer mortality in females. The majority of cases of ovarian carcinomas are not identified until a late stage. Identifying the molecular changes that occur during the development and progression of ovarian cancer is an urgent requirement. MicroRNAs (miRNAs) have been identified as gene expression regulators that induce mRNA degradation or translation blockade through pairing to the 3′ untranslated region (3-‘UTR) of the target mRNAs. In the present study, miR-222 was observed to be frequently upregulated in ovarian cancer. miR-222 upregulation induced an enhancement of ovarian cancer cell proliferation potential, possibly by downregulating its target, P27Kip1. A bioinformatic analysis showed that the 3′-UTR of the P27Kip1 mRNA contained a highly-conserved putative miR-222 binding site. Luciferase reporter assays demonstrated that P27Kip1 was a direct target of miR-222. Consistently, there was an inverse correlation between the P27Kip1 and miR-222 expression levels in the ovarian cancer cell lines and tissues. Overall, the present results suggest that miR-222 upregulation in human ovarian cancer may promote ovarian cancer cell proliferation during ovarian carcinogenesis.

Quercetin induces endoplasmic reticulum stress to enhance cDDP cytotoxicity in ovarian cancer: involvement of STAT3 signaling

There is an urgent need to make cisplatin (cDDP) more effective and less toxic in the treatment of ovarian cancer for its systemic side effects and high resistance rate. In this study, we investigated the effect of quercetin (Qu) pretreatment on the potentiation of cDDP in ovarian cancer. We found that Qu pretreatment significantly enhanced cDDP cytotoxicity in an ovarian cancer cell line and primary cancer cells. In addition, we demonstrated that Qu elicited obvious endoplasmic reticulum stress (ERS) and activated all three branches of ERS in ovarian cancer. Specific inhibitors of each ERS pathway, as well as the general ERS stabilizer tauroursodeoxycholic acid, notably diminished such enhancing effects. Furthermore, Qu notably suppressed STAT3 phosphorylation, leading to downregulation of the BCL‐2 gene downstream of STAT3. Moreover, blocking ERS restored the protein levels of phosphorylated STAT3 as well as BCL‐2 expression, thus abolishing the chemosensitization potency of Qu; these results revealed that Qu affected the STAT3 pathway to enhance cDDP cytotoxicity, and this effect involved ERS signaling. In a xenograft mouse model of ovarian cancer, Qu enhanced the antitumor effect of cDDP. Tumors from mice treated with cDDP in combination with Qu pretreatment had repressed STAT3 phosphorylation, lower BCL‐2 and higher apoptosis levels compared with those from the other groups. Meanwhile, Qu markedly reduced the elevation of blood creatinine during cDDP intervention. These data indicate that Qu pretreatment potentiates the antitumor effects of cDDP in ovarian cancer while protecting the kidneys against damage. Therefore the strategy of Qu pretreatment may be beneficial in enhancing the therapeutic efficacy of cDDP against ovarian cancer.

Quercetin induces protective autophagy and apoptosis through ER stress via the p-STAT3/Bcl-2 axis in ovarian cancer

Quercetin (3,3′,4′,5,7-pentahydroxyflavone, Qu) is a promising cancer chemo-preventive agent for various cancers because it inhibits disease progression and promotes apoptotic cell death. In our previous study, we demonstrated that Qu could evoke ER stress to enhance drug cytotoxicity in ovarian cancer (OC). However, Qu-induced ER stress in OC is still poorly understood. Here, we demonstrated that Qu evoked ER stress to involve in mitochondria apoptosis pathway via the p-STAT3/Bcl-2 axis in OC cell lines and in primary OC cells. Unexpectedly, inhibition of ER stress did not reverse Qu-induced cell death. Further functional studies revealed that Qu-induced ER stress could activate protective autophagy concomitantly by activating the p-STAT3/Bcl-2 axis in this process. Moreover, the autophagy scavenger 3-MA was shown to enhance Qu’s anticancer effects in an ovarian cancer mice xenograft model. These findings revealed a novel role of ER stress as a “double edge sword” participating in Qu-induced apoptosis of OC and might provide a new angle to consider in clinical studies of biological modifiers that may circumvent drug resistance in patients by targeting protective autophagy pathways.

MARCKS contributes to stromal cancer-associated fibroblast activation and facilitates ovarian cancer metastasis

The Cancer Genome Atlas network has revealed that the ‘mesenchymal’ epithelial ovarian cancer (EOC) subtype represents the poorest outcome, indicating a crucial role of stromal cancer-associated fibroblasts (CAFs) in disease progression. The cooperative role of CAFs in EOC metastasis has long been recognized, but the mechanisms of stromal CAFs activation are still obscure. Therefore, we carried out an integrative analysis to identify the regulator genes that are responsible for CAFs activation in microdissected tumor stroma profiles. Here, we determined that myristoylated alanine-rich C-kinase substrate (MARCKS) was highly expressed in ovarian stroma, and was required for the differentiation and tumor promoting function of CAFs. Suppression of MARCKS resulted in the loss of CAF features, and diminished role of CAFs in supporting tumor cell growth in 3D organotypic cultures and in murine xenograft model. Mechanistically, we found that MARCKS maintained CAF activation through suppression of cellular senescence and activation of the AKT/Twist1 signaling. Moreover, high MARCKS expression was associated with poor patient survival in EOC. Collectively, our findings identify the potential of MARCKS inhibition as a novel stroma-oriented therapy in EOC.

Activation of Integrin β1 Mediates the Increased Malignant Potential of Ovarian Cancer Cells Exerted by Inflammatory Cytokines

Epithelial ovarian cancer (EOC) is a highly lethal gynecological malignancy since it could not be discovered until at late stage. Identifying the molecular phenotype alteration during the development and progression of ovarian cancer is an urgent demand for the targeted intervention therapy. Recently, inflammation and Integrin beta 1(ITGB1), a subunit of heterodimeric transmembrane receptors family, had been pointed out to be involved in promoting ovarian tumorigenesis and cancer progression, respectively. However, the relationship between ITGB1 and the inflammatory mediators in ovarian cancer progression remains obscure. In the present study, ITGB1 was observed to be frequently upregulated in ovarian cancer, overexpression of ITGB1 led to a more invasive and mesenchymal phenotype. Furthermore, our results also provided evidence concerning the role of inflammatory cytokines (IL-6, TGF-β1 and SDF-1) in ITGB1 expression as well as in the malignant potential of ovarian cancer cells. Consistently, sh-RNA mediated knocking down of ITGB1 evidently reduced tumor growth and peritoneal dissemination in in vivo Nod-scid SKOV3 orthotopic xenograft mice. Overall, the present data suggested that ITGB1 upregulation was involved in the regulation of tumorigenesis and disease exacerbation exerted by inflammatory cytokines as IL-6, TGF-β1 and SDF-1, and suggested that targeting ITGB1 and the underlying inflammatory modulator was an attractive strategy for therapeutic intervention during ovarian carcinogenesis.

Reprogramming of stromal fibroblasts by SNAI2 contributes to tumor desmoplasia and ovarian cancer progression

BackgroundMolecular profiling in ovarian cancer (OC) revealed that the desmoplasia subtype presented the poorest prognosis, highlighting the contribution of stromal fibroblasts in tumor progression. This study aimed to investigate the molecular characteristics of SNAI2 driving the transcriptional reprogramming of fibroblasts within tumors.MethodsSNAI2 expression was evaluated in microdissected profiles of various cancers and in various molecular subtypes of OC. Gene set enrichment analysis (GSEA) and single sample GSEA (ssGSEA) were performed to explore the correlation between SNAI2 and stromal fibroblast activation. The SNAI2 defined signature in the mesenchymal OC subtype was identified through an integrative analysis of the TCGA and the Tothill datasets. The predictive value of this signature was validated in independent datasets. SNAI2 expression alteration influence of tumor growth in primary CAFs was evaluated in 3D organotypic and murine xenograft models.ResultsWe demonstrated that SNAI2 was frequently activated in the tumor stroma, correlated with fibroblast activation and worse patient outcome in OC. SNAI2 transformed normal fibroblasts to a CAF-like state and boosted their tumor–supporting role in 3D organotypic culture and in OC xenograft model. SNAI2 drove a transcriptional signature in the mesenchymal subtype of OC that contributed to tumor desmoplasia, which fed back to increase SNAI2 expression and sustain fibroblast activation.ConclusionsOur results address the role of SNAI2 in reprogramming stromal fibroblasts. The identified SNAI2 mesenchymal signature has both a predictive value and biological relevance and might be a therapeutic target for stroma-oriented therapy against the desmoplasia OC subtype.

Metformin Suppresses Tumor Progression by Inactivating Stromal Fibroblasts in Ovarian Cancer

Ovarian cancer is a devastating disease due to its high incidence of relapse and chemoresistance. The tumor microenvironment, especially the tumor stroma compartment, was proven to contribute tremendously to the unsatisfactory chemotherapeutic efficacy in ovarian cancer. Cytotoxic agents not only effect tumor cells, but also modulate the phenotype and characteristics of the vast stromal cell population, which can in turn alter the tumor cell response to chemointervention. In this study, we focused on the tumor stroma response to cytotoxic agents and the subsequent effect on the ovarian cancer tumor cells. First, we found a significant stromal overexpression of IL6 in patient samples that received cisplatin-based treatment, which was further validated in purified fibroblasts challenged with cisplatin. Stromal fibroblast–derived IL6 was proven to mediate ovarian cancer tumor cell chemoresistance. For the first time, we found that the tumor stroma of patients with routine metformin administration exhibited lower IL6 expression. Thus, we presumed that metformin was a potent alleviator of stromal inflammation in ovarian cancer. We found that metformin partly reversed cisplatin-stimulated IL6 secretion in the stromal fibroblasts and attenuated fibroblast-facilitated tumor growth in 3D organotypic cocultures and murine xenograft models. Mechanistically, we found that metformin inhibited IL6 secretion via suppressing NFκB signaling, an upstream controller of stromal inflammation. Collectively, our findings introduced a novel mechanism of metformin in suppressing ovarian cancer progression through diminishing chemotherapy-induced stromal activation. Therefore, we provide an alternative therapeutic option in targeting stromal inflammation and a potential scheme of combination therapy to improve the chemosensitivity in ovarian cancer. Mol Cancer Ther; 17(6); 1291–302. ©2018 AACR.

Isoform expression patterns of EPHA10 protein mediate breast cancer progression by regulating the E-Cadherin and β-catenin complex

Overexpression of EPHA10 protein was reported in concomitance with clinical severity of breast cancer. In this study, we annotate overexpression of EPHA10 protein with changes of isoform expression as EphA10s (EPHA10 isoform 2) and EphA10 (EPHA10 isoform 3). In the process of malignant transformation, secretory protein EphA10s is in low expression, and pseudo-kinase EphA10 is overexpressed and cytoplasmically enriched. Down-regulated EphA10s blunts stabilization of membrane-associate β-catenin via the interaction with ephrin A5. Cytoplasmic EphA10 maintains phosphorylation of E-cadherin. Restoring isoform expression pattern by up-regulated EphA10s and down-regulated cytoplasmic EphA10 inhibits cell invasion and lymph node metastasis by strengthening the stability of the complex of E-cadherin and β-catenin in membrane. Taken together, we defined the novel interaction via expression patterns of EphA10s and EphA10 that promote malignant transformation of breast cancer, and demonstrated the potential benefit in clinical usage.

Targeting Leptin as a Therapeutic Strategy against Ovarian Cancer Peritoneal Metastasis.

BACKGROUND/AIMS Epithelial ovarian cancer (OC) is the leading cause of death in patients with gynecologic malignancy. Malignant ascites, a shared symptom of advanced OC patients, plays an important role in the peritoneal metastasis cascade of OC. Since leptin existed in great amount in malignant ascites, we speculated that it might be involved in the modulation of tumor cells malignant behavior. METHOD Here, we demonstrated that blocking of leptin could significantly suppress ovarian malignant ascitesinduced metastatic aggravation of OC cells. Furthermore, our results suggested that leptin was highly expressed in OC and correlated with poor outcome of OC patients. Recombinant leptin notably promoted the migration, invasion and proliferation of OC cells. RESULT Mechanistically, we found that leptin induced epithelial-mesenchymal transition (EMT) program in OC cells through the activation of the PI3K/Akt/mTOR pathway. Pharmacological inhibition of the PI3K/Akt/mTOR pathway partly impaired leptin-induced malignant transformation of OC cells. More importantly, our in vivo xenograft experiment showed that blocking of leptin could dramatically inhibit OC cells peritoneal dissemination. CONCLUSION Collectively, this study emphasized the importance of leptin in OC progression and illustrated a novel mechanism that the PI3K/Akt/mTOR pathway was involved in leptin-induced EMT. Our findings provide new insights into leptin exertion on OC metastasis and identify the potential of leptin neutralizing as a novel strategy against OC peritoneal dissemination.

C/EBPβ enhances platinum resistance of ovarian cancer cells by reprogramming H3K79 methylation

Chemoresistance is a major unmet clinical obstacle in ovarian cancer treatment. Epigenetics plays a pivotal role in regulating the malignant phenotype, and has the potential in developing therapeutically valuable targets that improve the dismal outcome of this disease. Here we show that a series of transcription factors, including C/EBPβ, GCM1, and GATA1, could act as potential modulators of histone methylation in tumor cells. Of note, C/EBPβ, an independent prognostic factor for patients with ovarian cancer, mediates an important mechanism through which epigenetic enzyme modifies groups of functionally related genes in a context-dependent manner. By recruiting the methyltransferase DOT1L, C/EBPβ can maintain an open chromatin state by H3K79 methylation of multiple drug-resistance genes, thereby augmenting the chemoresistance of tumor cells. Therefore, we propose a new path against cancer epigenetics in which identifying and targeting the key regulators of epigenetics such as C/EBPβ may provide more precise therapeutic options in ovarian cancer.In ovarian cancer, the mechanism of chemoresistance is a key question. Here, the authors demonstrate that C/EBPβ and DOT1L together increase methylation of H3K79, which upregulates expression of oncogenic genes and drives poor platinum response and poor survival in ovarian cancer.