Orthotopic Mouse Model Of Ovarian Cancer Research Articles

Abstract 7549: Overcoming resistance to anti-VEGF therapy via epigenetic regulation of BARD1

Abstract DNA methylation inhibitors such as 5-azacytidine (Aza) and 5-aza-2′-deoxycytidine have been extensively used in patients with hematologic disorders and other neoplasms since their approval by the FDA. However, global DNA demethylating agents can result in intolerable toxicities; therefore, targeted epigenetic modulation is needed. Here, we searched for epigenetic changes with adaptive resistance to anti-VEGF antibody (AVA) in the TME and a novel strategy for targeted demethylation. Methods: We examined methylation and transcriptional changes in orthotopic ovarian cancer models with emergence of AVA resistance. We developed a targeted demethylation strategy for BARD1 to enhance the effectiveness of AVA. We used a novel dCas9-CRISPR-based system for targeted BARD1 CpG demethylation (derived by fusing the deactivated Cas9 [dCas9] with the TET1 catalytic domain) delivered in vivo using a nanoliposomal carrier. Results: We identified BARD1 methylation and reduced expression as lead candidate with AVA resistance; multiple CpG island sites in the BARD1 gene from adaptive AVA-resistant tumors were methylated. Next, we investigated the biological effects of global and targeted DNA methylation. Azacytidine along with AVA therapy was tested in a series of models (fibrosarcoma, PDX and orthotopic ovarian cancer models) and resulted in reduced tumor burden compared with the control and monotherapy groups (p<0.01). Next, to determine whether targeted demethylated BARD1 would have antitumor effects in vivo, we used an orthotopic SKOV3ip1luc ovarian cancer mouse model. Mice were treated with DOPC-dCas9-TET1-sgcontrol- (control) and DOPC-dCas9-TET1-sgBARD1 (sgBARD1). Tumor weight in the sgBARD1-3 group was significantly (p<0.01) reduced compared with the control group with no significant change in mouse body weight. We found that BARD1 expression was significantly increased in sgBARD1-treated group compared with control (p<0.001). Next, to determine whether demethylated BARD1 would combine well with AVA therapy in the SKOV3ip1 model, we combined sgBARD1-3 with bevacizumab (bev); sgBARD1-3 alone led to a significant decrease in tumor burden compared with control groups. Moreover, tumor burden was significantly reduced in the sgBARD1-3 and bevacizumab combination group compared with the sgcontrol group and bev alone group. BARD1 expression was significantly increased in sgBARD1-3-treated and in combination tumor samples compared with controls. To check for potential off-target effects, we tested the efficacy of another sgBARD1 and found that tumor burden in the sgBARD1-1 group was significantly reduced compared with control group. Conclusion: Our novel targeted approach results in robust antitumor effects when combined with AVA therapy in multiple cancer models. Collectively, our findings provide a novel approach for gene targeted demethylation and could have implications for epigenetic therapies. Citation Format: Emine Bayraktar, Cristian Rodriguez-Aguayo, Elaine Stur, Sudhir Kumar, Lingegowda S. Mangala, Nazende Nur Bayram, Pahul Hanjra, Sara Corvigno, Stephen Baylin, Gabriel Lopez-Berestein, Anil K. Sood. Overcoming resistance to anti-VEGF therapy via epigenetic regulation of BARD1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7549.

Kynurenine in IDO1high cancer cell-derived extracellular vesicles promotes angiogenesis by inducing endothelial mitophagy in ovarian cancer

BackgroundMitophagy, a prominent cellular homeostasis process, has been implicated in modulating endothelial cell function. Emerging evidence suggests that extracellular vesicles (EVs) participate in intercellular communication, which could modulate tumor angiogenesis, a hallmark of ovarian cancer (OC) progression. However, the underlying mechanisms through how EVs regulate endothelial mitophagy associated with tumor angiogenesis during OC development remain obscure.MethodsThe effect of cancer cell-derived EVs on endothelial mitophagy and its correlation with tumor angiogenesis and OC development were explored by in vitro and in vivo experiments. Multi-omics integration analysis was employed to identify potential regulatory mechanisms of cancer cell-derived EVs on endothelial mitophagy, which is involved in tumor angiogenesis associated with OC development. These insights were then further corroborated through additional experiments. An orthotopic OC mouse model was constructed to assess the antiangiogenic and therapeutic potential of the Indoleamine 2,3 dioxygenase-1 (IDO1) inhibitor.ResultsCancer cell-derived EVs promoted tumor angiogenesis via the activation of endothelial mitophagy, contributing to the growth and metastasis of OC. The aberrantly high expression of IDO1 mediated abnormal tryptophan metabolism in cancer cells and promoted the secretion of l-kynurenine (L-kyn)-enriched EVs, with associated high levels of L-kyn in EVs isolated from both the tumor tissues and patient plasma in OC. EVs derived from IDO1high ovarian cancer cells elevated nicotinamide adenine dinucleotide (NAD +) levels in endothelial cells via delivering L-kyn. Besides, IDO1high ovarian cancer cell-derived EVs upregulated sirt3 expression in endothelial cells by increasing acetylation modification. These findings are crucial for promoting endothelial mitophagy correlated with tumor angiogenesis. Notably, both endothelial mitophagy and tumor angiogenesis could be suppressed by the IDO1 inhibitor in the orthotopic OC mouse model.ConclusionsTogether, our findings unveil a mechanism of mitophagy in OC angiogenesis and indicate the clinical relevance of EV enriched L-kyn as a potential biomarker for tumorigenesis and progression. Additionally, IDO1 inhibitors might become an alternative option for OC adjuvant therapy.Graphical

Abstract PR016: Carcinoma-associated mesenchymal stem cells promote ovarian cancer metastasis by increasing tumor heterogeneity through direct mitochondrial transfer

Abstract Ovarian cancer is characterized by early, diffuse metastatic spread with most women presenting with widespread abdominal metastasis at the time of diagnosis. Prior work demonstrates carcinoma-associated mesenchymal stem cells (CA-MSCs) enhance ovarian cancer metastasis through a process of direct cellular interaction and formation of heterocellular CA-MSC and tumor cell complexes. Here we demonstrate CA-MSCs enhance metastasis via increasing tumor cell heterogeneity through mitochondrial donation. CA-MSCs directly interact with ovarian cancer cells forming tunneling nanotubules (TNTs). CA-MSCs transfer live mitochondria via these TNTs to ovarian cancer cells. This mitochondrial donation preferentially occurs in ovarian cancer cells with the least endogenous mitochondria (‘mito poor’ cancer cells). Mito poor cancer cells demonstrate decreased proliferation, increased sensitivity to chemotherapy and decreased oxidative phosphorylation compared to ‘mito rich’ cancer cells. CA-MSCs rescue the phenotype of these mito poor cancer cells restoring their proliferative capacity, increasing chemotherapy resistance and increasing oxidative phosphorylation. We validated these findings in a fully autologous system using CA-MSCs and cancer cells derived from the same patient to prevent confounding effects of cellular response to foreign organelle/DNA. Using a knockdown of the mitochondrial motor protein, MIRO1, we demonstrate mitochondrial transfer is necessary for the CA-MSC-mediated rescue of mito poor cancer cells. We developed a haplotype-specific quantification of mitochondrial DNA to differentiate CA-MSC derived mitochondria from endogenous tumor cell mitochondria. We used this system to both quantify the amount of CA-MSC mitochondrial donation and to demonstrate CA-MSC donated mitochondria persist in tumor cells over at least 14 days. Importantly, CA-MSC mitochondrial donation occurs in vivo and is associated with decreased survival in an orthotopic ovarian cancer mouse model. A DNA barcoding system was used to quantify tumor cell clonal heterogeneity. Using this system, we demonstrate CA-MSCs significantly enhance tumor cell heterogeneity, particularly during metastasis. This increase in tumor cell heterogeneity is dependent on CA-MSC mitochondrial transfer. Collectively, we report CA-MSC mitochondrial transfer as a critical mediator of ovarian cancer survival, heterogeneity and metastasis representing a potentially powerful therapeutic target. Citation Format: Leonard G. Frisbie, Catherine A. Pressimone, Huda I. Atiya, Alexander T. Pearson, Lan G. Coffman. Carcinoma-associated mesenchymal stem cells promote ovarian cancer metastasis by increasing tumor heterogeneity through direct mitochondrial transfer [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr PR016.

FAK PROTAC Inhibits Ovarian Tumor Growth and Metastasis by Disrupting Kinase Dependent and Independent Pathways.

Focal adhesion kinase (FAK) is highly expressed in a variety of human cancers and is a target for cancer therapy. Since FAK kinase inhibitors only block the kinase activity of FAK, they are not highly effective in clinical trials. FAK also functions as a scaffold protein in a kinase-independent pathway. To effectively target FAK, it is required to block both FAK kinase-dependent and FAK-independent pathways. Thus, we tested a new generation drug FAK PROTAC for ovarian cancer therapy, which blocks both kinase and scaffold activity. We tested the efficacy of FAK PROTAC and its parent kinase inhibitor (VS-6063) in ovarian cancer cell lines in vitro by performing cell functional assays including cell proliferation, migration, invasion. We also tested in vivo activity in orthotopic ovarian cancer mouse models. In addition, we assessed whether FAK PROTAC disrupts kinase-dependent and kinase-independent pathways. We demonstrated that FAK PROTAC is highly effective as compared to its parent FAK kinase inhibitor VS-6063 in inhibiting cell proliferation, survival, migration, and invasion. FAK PROTAC not only inhibits the FAK kinase activity but also FAK scaffold function by disrupting the interaction between FAK and its interaction protein ASAP1. We further showed that FAK PROTAC effectively inhibits ovarian tumor growth and metastasis. Taken together, FAK PROTAC inhibits both FAK kinase activity and its scaffold protein activity by disrupting the interaction between FAK and ASAP1 and is highly effective in inhibiting ovarian tumor growth and metastasis.

Adipose-Derived Stem Cells Facilitate Ovarian Tumor Growth and Metastasis by Promoting Epithelial to Mesenchymal Transition Through Activating the TGF-β Pathway.

Adipose-derived stem cells (ADSC) are multipotent mesenchymal stem cells derived from adipose tissues and are capable of differentiating into multiple cell types in the tumor microenvironment (TME). The roles of ADSC in ovarian cancer (OC) metastasis are still not well defined. To understand whether ADSC contributes to ovarian tumor metastasis, we examined epithelial to mesenchymal transition (EMT) markers in OC cells following the treatment of the ADSC-conditioned medium (ADSC-CM). ADSC-CM promotes EMT in OC cells. Functionally, ADSC-CM promotes OC cell proliferation, survival, migration, and invasion. We further demonstrated that ADSC-CM induced EMT via TGF-β growth factor secretion from ADSC and the ensuing activation of the TGF-β pathway. ADSC-CM-induced EMT in OC cells was reversible by the TGF-β inhibitor SB431542 treatment. Using an orthotopic OC mouse model, we also provide the experimental evidence that ADSC contributes to ovarian tumor growth and metastasis by promoting EMT through activating the TGF-β pathway. Taken together, our data indicate that targeting ADSC using the TGF-β inhibitor has the therapeutic potential in blocking the EMT and OC metastasis.

Synthesis and biological evaluation of selective survivin inhibitors derived from the MX-106 hydroxyquinoline scaffold.

The survivin (BIRC5) expression is very low in normal differentiated adult tissues, but it is one of the most widely upregulated genes in tumor cells. The overexpression of survivin in many cancer types has been positively correlated with resistance to chemotherapy, tumor metastasis, and poor patient survival. Survivin is considered to be a cancer specific biomarker and serves as a potential cancer drug target. In this report, we describe the design and syntheses of a series of novel selective survivin inhibitors based on the hydroxyquinoline scaffold from our previously reported lead compound MX-106. The best compound identified in this study is compound 12b. Invitro, 12b inhibited cancer cell proliferation with an average IC50 value of 1.4μM, using a panel of melanoma, breast, and ovarian cancer cell lines. The metabolic stability of 12b improved over MX-106 by 1.7-fold (88 vs 51min in human microsomes). Western blot analyses demonstrated that treatments with 12b selectively decreased survivin protein levels, but negligibly affected other closely related members in the IAP family proteins, and strongly induced cancer cell apoptosis. Invivo, compound 12b effectively inhibited melanoma tumor growth when tested using a human A375 melanoma xenograft model. Further evaluation using an aggressive, orthotopic ovarian cancer mouse model showed that 12b was highly efficacious in suppressing both primary tumor growth in ovaries and tumor metastasis to multiple peritoneal organs. Collectively, results in this study strongly suggest that the hydroxyquinoline scaffold, represented by 12b and our earlier lead compound MX-106, has abilities to selectively target survivin and is promising for further preclinical development.

An Orthotopic Mouse Model of Ovarian Cancer using Human Stroma to Promote Metastasis.

Ovarian cancer is characterized by early, diffuse metastasis with 70% of women having metastatic disease at the time of diagnosis. While elegant transgenic mouse models of ovarian cancer exist, these mice are expensive and take a long time to develop tumors. Intraperitoneal injection xenograft models lack human stroma and do not accurately model ovarian cancer metastasis. Even patient derived xenografts (PDX) do not fully recapitulate the human stromal microenvironment as serial PDX passages demonstrate significant loss of human stroma. The ability to easily model human ovarian cancer within a physiologically relevant stromal microenvironment is an unmet need. Here, the protocol presents an orthotopic ovarian cancer mouse model using human ovarian cancer cells combined with patient-derived carcinoma-associated mesenchymal stem cells (CA-MSCs). CA-MSCs are stromal progenitor cells, which drive the formation of the stromal microenvironment and support ovarian cancer growth and metastasis. This model develops early and diffuses metastasis mimicking clinical presentation. In this model, luciferase expressing ovarian cancer cells are mixed in a 1:1 ratio with CA-MSCs and injected into the ovarian bursa of NSG mice. Tumor growth and metastasis are followed serially over time using bioluminescence imaging. The resulting tumors grow aggressively and form abdominal metastases by 14 days post injection. Mice experienced significant decreases in body weight as a marker of systemic illness and increased disease burden. By day 30 post injection, mice met endpoint criteria of >10% body weight loss and necropsy confirmed intra-abdominal metastasis in 100% of mice and 60%-80% lung and parenchymal liver metastasis. Collectively, orthotopic engraftment of ovarian cancer cells and stroma cells generates tumors that closely mimic the early and diffuse metastatic behavior of human ovarian cancer. Furthermore, this model provides a tool to study the role of ovarian cancer cell: stroma cell interactions in metastatic progression.

A Luminacin D Analog HL142 Inhibits Ovarian Tumor Growth and Metastasis by Reversing EMT and Attenuating the TGFβ and FAK Pathways.

Epithelial to mesenchymal transition (EMT) is known to contribute to tumor metastasis and chemoresistance. Reversing EMT using small molecule inhibitors to target EMT associated gene expression represents an effective strategy for cancer treatment. The purpose of this study is to test whether a new luminacin D analog HL142 reverses EMT in ovarian cancer (OC) and has the therapeutic potential for OC. We chemically synthesized HL142 and tested its functions in OC cells in vitro and its efficacy in inhibiting ovarian tumor growth and metastasis in vivo using orthotopic OC mouse models. We first demonstrate that ASAP1 is co-amplified and interacts with the focal adhesion kinase (FAK) protein in serous ovarian carcinoma. HL142 inhibits ASAP1 and its interaction protein FAK in highly invasive OVCAR8 and moderately invasive OVCAR3 cells. HL142 inhibits EMT phenotypic switch, accompanied by upregulating epithelial marker E-cadherin and cytokeratin-7 and downregulating mesenchymal markers vimentin, β-catenin, and snail2 in both cell lines. Functionally, HL142 inhibits proliferation, colony formation, migration, and invasion. HL142 also sensitizes cell responses to chemotherapy drug paclitaxel treatment and inhibits ovarian tumor growth and metastasis in orthotopic OC mouse models. We further show that HL142 attenuates the TGFβ and FAK pathways in vitro using OC cells and in vivo using orthotopic mouse models.

Zinc regulates primary ovarian tumor growth and metastasis through the epithelial to mesenchymal transition

BackgroundThe trace element zinc plays an indispensable role in human health and diseases including cancer due to its antioxidant properties. While zinc supplements have been used for cancer prevention, zinc is also a risk factor for cancer development. It is still unclear how zinc plays a role in ovarian cancer. MethodsTo understand how zinc contributes to ovarian tumor growth and metastasis, we examined whether zinc contributes to tumor metastasis by regulating epithelial to mesenchymal transition (EMT) using ovarian cancer cells in vitro. Cell migration and invasion were examined using transwell plates and EMT markers were examined using Western blot. Primary ovarian tumor growth and metastasis were assessed using orthotopic ovarian cancer mouse models in vivo. ResultsZinc promoted EMT, while TPEN (N, N, N’, N’-tetrakis-(2-pyridylmethyl)-ethylenediamine), a membrane-permeable selective zinc chelator, inhibited EMT in a dose dependent manner in ovarian cancer cells. Moreover, zinc promoted ovarian cancer cell migration and invasion, while TPEN inhibited cell migration and invasion. Zinc activated expression of the metal response transcriptional factor-1 (MTF-1), while TPEN inhibited MTF-1 expression in a dose dependent manner. Knockout of MTF-1 inhibited zinc-induced cell migration, invasion and augmented the inhibitory effect of TPEN on cell migration and invasion. Loss of MTF-1 attenuated zinc-induced ERK1/2 and AKT activation and augmented the effect of TPEN in attenuating the ERK1/2 and AKT pathways. TPEN effectively inhibited primary ovarian tumor growth and metastasis in an orthotopic ovarian cancer mouse model by suppressing EMT. Conclusionzinc contributes to ovarian tumor metastasis by promoting EMT through a MTF-1 dependent pathway. Zinc depletion by TPEN may be a novel approach for ovarian cancer therapy by inhibiting EMT and attenuating the ERK1/2 and AKT pathways.

Abstract 4184: Genetic and pharmacological disruption of survivin suppressed primary and metastatic tumor growth by attenuating TGFB pathway in ovarian cancer

Abstract Introduction: Survivin, a member of the inhibitor of apoptosis family, is upregulated in multiple cancers including ovarian cancer, but is rarely detectable in normal tissues. Therefore, it is a potential drug target. However, targeting survivin is still challenge and small molecule inhibitors failed in clinical trials. It's very important to understand how survivin contributes to tumor development. In this study, we investigated the role of survivin in ovarian cancer using ovarian cancer cell lines in vitro and mouse models in vivo and examined how survivin contributes to ovarian primary ovarian tumor growth and metastasis by examining epithelial to mesenchymal transition (EMT). Methods: To define the role of survivin in EMT in ovarian cancer cells, we established survivin knockout cell lines using lentiviral CRISPR/Cas9 nickase and pharmacologically inhibited survivin with a novel inhibitor MX106. We examined EMT markers, migration and invasion assays in survivin disrupted ovarian cancer cells using Transwell plates. We also assessed primary ovarian tumor growth and metastasis in an orthotopic ovarian cancer mouse models through intrabursal injecting survivin KO cell line and also treatment using MX106. Findings: We found that disruption of survivin expression inhibited EMT by attenuating the TGFβ pathway in ovarian cancer cells. Cell proliferation, migration, and invasion were significantly inhibited in survivin knockout or MX106 treatment in SKOV3 and OVCAR3 cell lines compared to control cells. Inhibition of survivin sensitized cell responses to paclitaxel treatment and overcame chemoresistance in vitro. Lentiviral CRISPR/Cas9 mediated survivin knockout or MX106 treatment efficiently inhibited primary ovarian tumor growth and metastasis in orthotopic ovarian cancer mouse models. Conclusions: Our data demonstrate that inhibition of survivin using either genetic knockout or a novel inhibitor MX106 suppresses primary ovarian tumor growth and metastasis by attenuating TGFβ pathway. MX106, as a novel survivin inhibitor effectively overcame chemoresistance compared to commercial YM155, which provides a novel approach for ovarian cancer therapy. Citation Format: Junming Yue. Genetic and pharmacological disruption of survivin suppressed primary and metastatic tumor growth by attenuating TGFB pathway in ovarian cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4184.

The regulation of RNA Polymerase II mediated transcription by Caspase-8 in ovarian cancer.

e18082 Background: According to the WHO, in 2018, the number of new cases and mortality worldwide due to ovarian cancer, were 295,414 and 184,799, respectively, making it one of the most lethal gynaecological cancers in the world. The standard therapy of ovarian cancers is still comprehensive cytoreductive surgery followed by a combination of platinum-taxane based primary chemotherapy. Second line therapies include Carboplatin or Cisplatin in combination with Paclitaxel, PLD or Gemcitabine, with or without Bevacizumab. Unfortunately, late stage ovarian cancer cases are still incurable, however, several new drugs are under development or are undergoing clinical trials. At present, these new approaches can only stabilize the disease or delay its recurrence. Caspase-8, the predominant initiator of the extrinsic apoptotic pathway, also plays critical roles in a number of other non-apoptotic functions. It is also frequently down-regulated in ovarian cancer and we wanted to understand how this down-regulation could support the development of ovarian cancer. Methods: The analysis of the association between CASP8 expression and patient prognosis in ovarian cancer patients found that low CASP8 expression was significantly correlated with poor OS, with a median OS of 37.43 (low expression) and 49.97 (high expression) months, and higher clinical stages. CRISPR/Cas9 mediated CASP8 KO in multiple high- and low-grade ovarian cancer cell lines resulted in significant increases in their invasiveness. Results: Caspase-8 interactome analysis revealed that it can regulate the RNA Pol II mediated transcription, which was corroborated through multiple in vitro and ex vivo experiments. Global Transcriptomics and Proteomics analysis of the KO cells revealed significant upregulation of genes involved in metastasis, which was again verified in in vitro and ex vivo experiments. Additionally, the KO cells were significantly resistant towards standard chemotherapeutics like Carboplatin, a transcription inhibitor, either alone or in combination with Paclitaxel. Conclusions: Presently, we are working on orthotopic ovarian cancer mouse models to validate - the potential of Caspase-8 to regulate metastasis; and the targeting of RNA Pol II to sensitize them to standard chemotherapeutics. We are also developing organoid banks from patient derived ovarian cancer tissues, with low Caspase-8 expression, to validate the upregulation of genes identified in our ‘omics’ data and the potential of targeting them, along with RNA Pol II, to sensitize them to standard chemotherapeutics.

Ovarian Primary and Metastatic Tumors Suppressed by Survivin Knockout or a Novel Survivin Inhibitor.

Survivin, a member of the inhibitor of apoptosis family, is upregulated in multiple cancers including ovarian cancer, but is rarely detectable in normal tissues. We previously reported that survivin promoted epithelial-to-mesenchymal transition (EMT) in ovarian cancer cells, suggesting that survivin may contribute to ovarian tumor metastasis and chemoresistance. In this study, we tested whether knockout or pharmacologic inhibition of survivin overcomes chemoresistance and suppresses tumor metastasis. The genetic loss of survivin suppressed tumor metastasis in an orthotopic ovarian cancer mouse model. To pharmacologically test the role of survivin on ovarian tumor metastasis, we treated chemo-resistant ovarian cancer cells with a selective survivin inhibitor, MX106, and found that MX106 effectively overcame chemoresistance in vitro MX106 inhibited cell migration and invasion by attenuating the TGFβ pathway and inhibiting EMT in ovarian cancer cells. To evaluate the efficacy of MX106 in inhibiting ovarian tumor metastasis, we treated an orthotopic ovarian cancer mouse model with MX106, and found that MX106 efficiently inhibited primary tumor growth in ovaries and metastasis in multiple peritoneal organs as compared with vehicle-treated control mice. Our data demonstrate that inhibition of survivin using either genetic knockout or a novel inhibitor MX106 suppresses primary ovarian tumor growth and metastasis, supporting that targeting survivin could be an effective therapeutic approach in ovarian cancer.

Abstract 3579: Long non-coding RNA ADAMTS9-AS2 inhibits ovarian tumor growth via Annexin A1

Abstract Non-coding RNAs (ncRNA), which account for more than 75% genome transcripts, have unique functions in regulating cancer pathogenesis. Long non-coding RNAs (lncRNAs) are key regulators of gene expression and are involved in cancer progression and metastasis. However, the role of long non-coding RNAs (lncRNAs) in high-grade serous ovarian cancer (HGSC) is not well understood. We used the NCode™ non-coding RNA array to screen downregulated lncRNAs in HGSCs. After analyzing the array data of lncRNAs in HGSCs (n=29) and normal ovarian (n=11) samples, the probes mapping to the top 25 most down-regulated non-coding RNAs were analyzed. Two lncRNAs (ADAMTS9-AS1 and ADAMTS9-AS2) were identified as the antisense of gene ADAMTS9, and we validate by in vitro translation assay, q-RT-PCR, in-situ hybridization and the biological functions of ADAMTS9-AS2 in ovarian cancer cells. Moreover, using A2780-CP20 orthotopic mouse models of ovarian cancer, we further demonstrated restoring ADAMTS9-AS2 resulted in profound reduction of tumor growth and metastasis. Here, we demonstrate that ADAMTS9-AS2 is highly down-regulated (5.01x10-13 and 1.6x10-19) in ovarian cancers. Overexpression of ADAMTS9-AS2 leads to significantly increased apoptosis (7.5% control and 19.5% AS2OE) and decreased proliferation (49.5% control and 37.0% AS2OE) compared with controls. Consistently, increased expression of ADAMTS9-AS2 led to significantly reduced tumor burden in A2780-CP20 orthotopic ovarian cancer mouse models. We identified the promoter region of Annexin A1 as the major target of ADAMTS9-AS2. The binding of lncRNA ADAMTS9-AS2 to the promoter region can facilitate the expression of tumor suppressor Annexin A1 thereby decrease the proliferation and increase apoptosis of cancer cells. Collectively, our data point to an important role for ADAMTS9-AS2 as a tumor suppressor in ovarian cancer. Note: This abstract was not presented at the meeting. Citation Format: Cristian Rodriguez-Aguayo, Emine Bayraktar, Lingegowda S. Mangala, Cristina Ivan, Gabriel Lopez-Berestein, Anil K. Sood. Long non-coding RNA ADAMTS9-AS2 inhibits ovarian tumor growth via Annexin A1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3579.

Cyclin D1 silencing impairs DNA double strand break repair, sensitizes BRCA1 wildtype ovarian cancer cells to olaparib

ObjectivePoly(ADP-ribose) polymerase inhibitors (PARPi) are active in cancer cells that have impaired repair of DNA by the homologous recombination (HR) pathway. Strategies that disrupt HR may sensitize HR-proficient tumors to PARP inhibition. As a component of the core cell cycle machinery, cyclin D1 has unexpected function in DNA repair, suggesting that targeting cyclin D1 may represent a plausible strategy for expanding the utility of PARPi in ovarian cancer. MethodsBRCA1 wildtype ovarian cancer cells (A2780 and SKOV3) were treated with a combination of CCND1 siRNA and olaparib in vitro. Cell viability was assessed by MTT. The effects of the combined treatment on DNA damage repair and cell cycle progression were examined to dissect molecular mechanisms. In vivo studies were performed in an orthotopic ovarian cancer mouse model. Animals were treated with a combination of lentivirus-mediated CCND1 shRNA and olaparib or olaparib plus scrambled shRNA. Molecular downstream effects were examined by immunohistochemistry. ResultsSilencing of cyclin D1 sensitized ovarian cancer cells to olaparib through interfering with RAD51 accumulation and inducing cell cycle G0/G1 arrest. Treatment of lentivirus-mediated CCND1-shRNA in nude mice statistically significantly augmented the olaparib response (mean tumor weight ± SD, CCND1-shRNA plus olaparib vs scrambled shRNA plus olaparib: 0.172 ± 0.070 g vs 0.324 ± 0.044 g, P< 0.05). ConclusionsSilencing of cyclin D1 combined with olaparib may lead to substantial benefit for ovarian cancer management by mimicking a BRCAness phenotype, and induction of G0/G1 cell cycle arrest.

MiR-199a-3p enhances cisplatin sensitivity of ovarian cancer cells by targeting ITGB8.

Drug resistance remains a large obstacle for the treatment of ovarian cancer. miRNAs have been reported to be involved in cisplatin (CDDP) resistance in ovarian cancer. The aim of the present study was to investigate the function and mechanism of miR-199a-3p in the CDDP resistance in ovarian cancer. We found that miR-199a-3p was significantly downregulated in chemoresistant ovarian cancer tissues, as well as CDDP-resistant SKOV3/CDDP cells, compared to chemosensitive carcinomas and SKOV3 cells. Restoration of miR-199a-3p in SKOV3/CDDP cells reduced cell proliferation, G1 phase cell cycle arrest, cell invasion, and increased cell apoptosis, resulting in enhanced CDDP sensitivity, while miR-199a-3p inhibition resulted in the opposite effects. Luciferase reporter assay showed that integrin β8 (ITGB8), one of the integrins that is involved in the regulation of cell cycle and motility, was a direct target of miR-199a-3p. Overexpression of miR-199a-3p downregulated ITGB8 expression via binding to its 3′-UTR. In addition, overexpression of ITGB8 restored CDDP resistance inhibited by miR-199a-3p. Moreover, orthotopic ovarian cancer mouse model showed that miR-199a-3p enhanced CDDP sensitivity of ovarian cancer in vivo. Therefore, our results indicate that miR-199a-3p enhances CDDP sensitivity of ovarian cancer cells through downregulating ITGB8 expression, and miR-199a-3p may serve as a therapeutic target for the treatment of ovarian cancer patients with CDDP-resistance.

Targeting the centriolar replication factor STIL synergizes with DNA damaging agents for treatment of ovarian cancer.

Advanced ovarian cancer is an incurable disease. Thus, novel therapies are required. We wished to identify new therapeutic targets for ovarian cancer. ShRNA screen performed in 42 ovarian cancer cell lines identified the centriolar replication factor STIL as an essential gene for ovarian cancer cells. This was verified in-vivo in orthotopic human ovarian cancer mouse models. STIL depletion by administration of siRNA in neutral liposomes resulted in robust anti-tumor effect that was further enhanced in combination with cisplatin. Consistent with this finding, STIL depletion enhanced the extent of DNA double strand breaks caused by DNA damaging agents. This was associated with centrosomal depletion, ongoing genomic instability and enhanced formation of micronuclei. Interestingly, the ongoing DNA damage was not associated with reduced DNA repair. Indeed, we observed that depletion of STIL enhanced canonical homologous recombination repair and increased BRCA1 and RAD51 foci in response to DNA double strand breaks. Thus, inhibition of STIL significantly enhances the efficacy of DNA damaging chemotherapeutic drugs in treatment of ovarian cancer.

Long Noncoding RNA Ceruloplasmin Promotes Cancer Growth by Altering Glycolysis.

Long noncoding RNAs (lncRNAs) significantly influence the development and regulation of genome expression in cells. Here, we demonstrate the role of lncRNA ceruloplasmin (NRCP) in cancer metabolism and elucidate functional effects leading to increased tumor progression. NRCP was highly upregulated in ovarian tumors, and knockdown of NRCP resulted in significantly increased apoptosis, decreased cell proliferation, and decreased glycolysis compared with control cancer cells. In an orthotopic mouse model of ovarian cancer, siNRCP delivered via a liposomal carrier significantly reduced tumor growth compared with control treatment. We identified NRCP as an intermediate binding partner between STAT1 and RNA polymerase II, leading to increased expression of downstream target genes such as glucose-6-phosphate isomerase. Collectively, we report a previously unrecognized role of the lncRNA NRCP in modulating cancer metabolism. As demonstrated, DOPC nanoparticle-incorporated siRNA-mediated silencing of this lncRNA in vivo provides therapeutic avenue toward modulating lncRNAs in cancer.

The HMG-CoA reductase inhibitor, simvastatin, exhibits anti-metastatic and anti-tumorigenic effects in ovarian cancer

Ovarian cancer is the 5th leading cause of cancer death among women in the United States. The mevalonate pathway is thought to be a potential oncogenic pathway in the pathogenesis of ovarian cancer. Simvastatin, a 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) inhibitor, is a widely used drug for inhibiting the synthesis of cholesterol and may also have anti-tumorigenic activity. Our goal was to evaluate the effects of simvastatin on ovarian cancer cell lines, primary cultures of ovarian cancer cells and in an orthotopic ovarian cancer mouse model. Simvastatin significantly inhibited cellular proliferation, induced cell cycle G1 arrest and apoptosis, and caused cellular stress via reduction in the enzymatic activity of HMGCR and inhibition of the MAPK and mTOR pathways in ovarian cancer cells. Furthermore, simvastatin induced DNA damage and reduced cell adhesion and invasion. Simvastatin also exerted anti-proliferative effects on primary cell cultures of ovarian cancer. Treatment with simvastatin in an orthotopic mouse model reduced ovarian tumor growth, coincident with decreased Ki-67, HMGCR, phosphorylated-Akt and phosphorylated-p42/44 protein expression. Our findings demonstrate that simvastatin may have therapeutic benefit for ovarian cancer treatment and be worthy of further exploration in clinical trials.

MiR-506: a regulator of chemo-sensitivity through suppression of the RAD51-homologous recombination axis.

Ovarian carcinoma is the most lethal gynecologic malignancy. Resistance to platinum is considered the major problem affecting prognosis. Our recent study established that microRNA-506 (miR-506) expression was closely associated with progression-free survival and overall survival in two independent patient cohorts totaling 598 epithelial ovarian cancer cases. Further functional study demonstrated that miR-506 could augment the response to cisplatin and olaparib through targeting RAD51 and suppressing homologous recombination in a panel of ovarian cancer cell lines. Systemic delivery of miR-506 in an orthotopic ovarian cancer mouse model significantly augmented the cisplatin response, thus recapitulating the clinical observation. Therefore, miR-506 plays a functionally important role in homologous recombination and has important therapeutic value for sensitizing cancer cells to chemotherapy, especially in chemo-resistant patients with attenuated expression of miR-506.

Abstract 5466: Integrative TCGA analyses identify Basonuclin1 (BNC1) as a key mediator for platinum resistance

Abstract Objective. We have previously shown that platinum-resistant (disease progression within 6 months of diagnosis) high-grade serous ovarian cancer (HGSOC) expresses higher levels of basonuclin1 (BNC1) compared to platinum-sensitive tumors (no disease progression for more than 2 years). Here, we aim to systematically examine the functional effects of BNC1 silencing on tumor sensitivity to platinum and other commonly used chemotherapeutic agents in multiple cancer models. Methods. An integrative analysis was performed using The Cancer Genome Atlas (TCGA) dataset to systematically identify genes associated with platinum-resistance in patients with HGSOC. The biological effects of BNC1, one of the lead candidates identified, were studied in HGSOC (HeyA8-MDR, PEO4), endometrioid ovarian (A2780-CP20), clear cell ovarian (ES2), and squamous cell lung (H1299) cancer models both in vitro and in vivo. The effects of BNC1 silencing or overexpression on the sensitivity of cancer cells to paclitaxel, gemcitabine, doxorubicin, and cisplatin treatments were assessed. Results. BNC1 expression was increased by more than two-fold in platinum-resistant tumors in the TCGA ovarian cancer dataset. BNC1 silencing increased the sensitivity of A2780-CP20, HeyA8-MDR, PEO4, ES2, and H1299 cells to cisplatin and doxorubicin treatments, but not to gemcitabine or taxane-based therapies. BNC1-silenced cells showed a 3-fold average increase in the percentage of apoptotic cells following cisplatin treatment, when compared to cells treated with control siRNA. Importantly, combination treatment of siBNC1 and cisplatin resulted in a 90% reduction in tumor burden in platinum-resistant A2780-CP20 and HeyA8-MDR orthotopic ovarian cancer mouse models when compared to control siRNA plus cisplatin treatment group. Overexpression of BNC1 in platinum-sensitive A2780 cells led to a 2.5-fold reduction in cisplatin sensitivity in vivo as measured by total tumor burden 4 weeks after therapy. Conclusion. Collectively, BNC1 represents an important target for enhancing platinum-sensitivity in ovarian and lung cancer. Targeting BNC1 in platinum-resistant malignancies may improve patient survival. Note: This abstract was not presented at the meeting. Citation Format: Sherry Y. Wu, Justyna Filant, Michael McGuire, Rajesha Rupaimoole, Sunila Pradeep, Anna Unruh, Herbrich Shelley, Cristina Ivan, Ruder Dennis, Cristian Rodriguez-Aguayo, Vasudha Sehgal, Takahito Miyake, Archana Nagaraja, Kshipra Gharpure, Guillermo Armaiz, Rebecca Previs, Gabriel Lopez-Berestein, Prahlad Ram, Keith Baggerly, Anil Sood. Integrative TCGA analyses identify Basonuclin1 (BNC1) as a key mediator for platinum resistance. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5466. doi:10.1158/1538-7445.AM2015-5466