Ovarian Carcinoma Cells Research Articles

Integrated proteomics identifies PARP inhibitor-induced prosurvival signaling changes as potential vulnerabilities in ovarian cancer

BRCA1/2-deficient ovarian carcinoma (OC) has been shown to be particularly sensitive to poly (ADP-ribose) polymerase inhibitors (PARPis). Furthermore, BRCA1/2 mutation status is currently used as a predictive biomarker for PARPi therapy. Despite providing a major clinical benefit to the majority of patients, a significant proportion of BRCA1/2-deficient OC tumors do not respond to PARPis for reasons that are incompletely understood. Using an integrated chemical, phospho- and ADP-ribosylation proteomics approach, we sought here to develop additional mechanism-based biomarker candidates for PARPi therapy in OC and identify new targets for combination therapy to overcome primary resistance. Using chemical proteomics with PARPi baits in a BRCA1-isogenic OC cell line pair, as well as patient-derived BRCA1-proficient and BRCA1-deficient tumor samples, and subsequent validation by coimmunoprecipitation, we showed differential PARP1 and PARP2 protein complex composition in PARPi-sensitive, BRCA1-deficient UWB1.289 (UWB) cells compared to PARPi-insensitive, BRCA1-reconstituted UWB1.289+BRCA1 (UWB+B) cells. In addition, global phosphoproteomics and ADP-ribosylation proteomics furthermore revealed that the PARPi rucaparib induced the cell cycle pathway and nonhomologous end joining (NHEJ) pathway in UWB cells but downregulated ErbB signaling in UWB+B cells. In addition, we observed AKT PARylation and prosurvival AKT-mTOR signaling in UWB+B cells after PARPi treatment. Consistently, we found the synergy of PARPis with DNAPK or AKT inhibitors was more pronounced in UWB+B cells, highlighting these pathways as actionable vulnerabilities. In conclusion, we demonstrate the combination of chemical proteomics, phosphoproteomics, and ADP-ribosylation proteomics can identify differential PARP1/2 complexes and diverse, but actionable, drug compensatory signaling in OC.

Bufogarlides A-C, three new bufadienolides with Δ 14,15 double bond from the skins of Bufo bufo gargarizans

Three new bufadienolides with a Δ 14,15 double bond, named bufogarlides A-C (1-3), together with three known analogs (4-6), were isolated from the skins of Bufo bufo gargarizans. Their structures were identified by analyses of spectroscopic data (1 D and 2 D NMR, HR-ESIMS), and comparison with the literature data. All the isolates were evaluated for their cytotoxic activities against ovarian carcinoma cell lines A2780 and SKOV3. Among them, compound 5 showed the highest potential for the growth inhibition of cancerous cells A2780 and SKOV3 with the IC50 values of 21.09 and 67.08 nM, respectively.

Extracellular Matrix Modulates Outgrowth Dynamics in Ovarian Cancer.

Ovarian carcinoma (OC) forms outgrowths that extend from the outer surface of an afflicted organ into the peritoneum. OC outgrowth formation is poorly understood due to the limited availability of cell culture models examining the behavior of cells that form outgrowths. Prompted by immunochemical evaluation of extracellular matrix (ECM) components in human tissues, laminin and collagen-rich ECM-reconstituted cell culture models amenable to studies of cell clusters that can form outgrowths are developed. It is demonstrated that ECM promotes outgrowth formation in fallopian tube non-ciliated epithelial cells (FNE) expressing mutant p53 and various OC cell lines. Outgrowths are initiated by cells that underwent outward translocation and retained the ability to intercalate into mesothelial cell monolayers. Electron microscopy, optical coherence tomography, and small amplitude oscillatory shear experiments reveal that increased ECM levels led to increased fibrous network thickness and high shear elasticity of the microenvironment. These physical characteristics are associated with outgrowth suppression. The low ECM microenvironment mimicks the viscoelasticity of malignant peritoneal fluid (ascites) and supports cell proliferation, cell translocation, and outgrowth formation. These results highlight the importance of the ECM microenvironment in modulating OC growth and can provide additional insights into the mode of dissemination of primary and recurrent ovarian tumors.

Chemical Composition and Antioxidant, Antiviral, Antifungal, Antibacterial and Anticancer Potentials of Opuntia ficus-indica Seed Oil

Opuntia ficus-indica (OFI) is a cactus that is widely cultivated in the Kingdom of Saudi Arabia especially in the Taif region due to its favorable weather for growing, and it has benefits as a food and traditional medicine. The aim of the current study was to chemically characterize Opuntia ficus-indica seed oil from Taif, Kingdom of Saudi Arabia, using GC-MS and HPLC analysis and evaluate its antioxidant, antiviral, antifungal, antibacterial and anticancer activities. Linolenic acid was the dominating fatty acid in OFI oil, followed by oleic acid, linoleic acid, palmitic acid and stearic acid. Total tocopherol (α-, β-, Ɣ-tocopherol) was found to be 24.02 μg/mL. Campesterol was the main phytosterol, followed by γ- & β -sitosterol, and Stigmasterol. The phenolic components scored 30.5 mg gallic acid equivalent per ml of oil with 89.2% antioxidant activity (% DPPH radical inhibition) at 200 µL/mL of OFI oil. OFI oil showed an inhibition efficacy against microbial strains especially Saccharomyces cervisiae with a diameter (28.3 ± 0.4), MBC (15 µg/mL) and MIC bacteriostatic (10 µg/mL). While OFI oil had no effect against Aspergillus niger, OFI oil showed weak inhibitory activity against A-2780 (Ovarian carcinoma) cell line, although it showed significant inhibitory activity against PC-3 (Prostate carcinoma) cell line. OFI oil exhibited an antiviral effect (22.67 ± 2.79%) at 300 µg/mL of Oil against herpes simplex type 2 (HSV-2) virus. The bioactive compounds of OFI oil, as well as its main biological activities, make it a promising candidate for the non-communicable disease management.

MiR-4284 inhibits sensitivity to paclitaxel in human ovarian carcinoma SKOV3ip1 and HeyA8 cells by targeting DMC1.

An increasing number of studies have confirmed that microRNAs (miRNAs) are involved in various biological processes, including tumor growth and drug resistance. MiR-4284 has been proved to be abnormally regulated in several cancers, but the function of miR-4284 in ovarian carcinoma (OC) is unclear. Paclitaxel resistance is a key obstacle in OC treatment. Here, the role of miR-4284 in cell sensitivity to paclitaxel in OC was investigated. Two OC cell lines (SKOV3ip1 and HeyA8) were utilized for the establishment of paclitaxel-resistant cell lines. Reverse transcription-quantitative PCR (RT-qPCR) was applied to analyze the levels of miR-4284 and potential mRNAs in OC cell lines. Western blotting was performed to evaluate the levels of DNA meiotic recombinase 1 (DMC1) protein and cell cycle-associated proteins. Identification of the relationship between miR-4284 and DMC1 was achieved by luciferase reporter assay. CCK-8 and flow cytometry assays were utilized for evaluating the impact of miR-4284 on the malignant characteristics of paclitaxel-resistant OC cells. MiR-4284 was upregulated in paclitaxel-resistant OC cell lines and correlated with an adverse prognosis in OC patients. Depletion of miR-4284 suppressed cell proliferation and cell cycle progression of paclitaxel-resistant OC. MiR-4284 targeted DMC1 which was downregulated in paclitaxel-resistant cells and reversed the inhibitory influence of miR-4284 silencing on the malignant characters of paclitaxel-resistant OC cells. MiR-4284 targets DMC1 to suppress sensitivity to paclitaxel in human OC cells.

Chemophototherapeutic Ablation of Doxorubicin-Resistant Human Ovarian Tumor Cells.

Porphyrin-phospholipid (PoP) liposomes loaded with Doxorubicin (Dox) have been demonstrated to be an efficient vehicle for chemophototherapy (CPT). Multidrug resistance (MDR) of cancer cells is a problematic phenomenon in which tumor cells develop resistance to chemotherapy. Herein, we report that Dox-resistant tumor cells can be ablated using our previously described formulation termed long-circulating Dox loaded in PoP liposomes (LC-Dox-PoP), which is a PEGylated formulation containing 2 mol. % of the PoP photosensitizer. In vitro studies using free Dox and LC-Dox-PoP showed that human ovarian carcinoma A2780 cells were more susceptible to Dox compared to the corresponding Dox-resistant A2780-R cells. When CPT was applied with LC-Dox-PoP liposomes, effective killing of both nonresistant and resistant A2780 cell lines was observed. An invivo study to assess the efficiency of LC-Dox-PoP showed effective tumor shrinkage and prolonged survival of athymic nude mice bearing subcutaneous Dox-resistant A2780-R tumor xenografts when they were irradiated with a red laser. Biodistribution analysis demonstrated enhanced tumoral drug uptake in Dox-resistant tumors with CPT, suggesting that increased drug delivery was sufficient to induce ablation of resistant tumor cells.

Efficacy of combining tumor treating fields (TTFields) with a PARP inhibitor in ovarian cell lines (300.5)

Objectives: PARP inhibition demonstrates clinical effectiveness in patients with solid tumors and deleterious BRCA mutations. The use of PARP inhibitors is specifically relevant in ovarian cancer, as one of three women with this malignancy harbor BRCA mutations. Tumor Treating Fields (TTFields) are alternating electric fields with antimitotic effects on cancerous cells, which are approved to treat patients with glioblastoma and malignant pleural mesothelioma. TTFields were shown to induce a state of BRCAness in several cancerous cell lines. The objective of this study was to explore the potential of combining TTFields with PARP inhibition for the treatment of ovarian cancer based on in vitro work. Methods: Ovarian carcinoma cells, A2780 (BRCA1/2 wild type) and OVCAR3 (BRCA1 wild type, BRCA2 mutated), were treated for 72 h with TTFields (at an intensity of 1.2 V/cm RMS and frequency of 200 kHz) using the in vitro system. The effectiveness of TTFields in combination with the PARP inhibitor niraparib was examined by measuring cell counts, clonogenic potential, overall effect (multiplicity product of cytotoxicity and clonogenicity), and apoptosis induction. Results: The application of TTFields to A2780 or OVCAR3 cells resulted in about 50% reduction in cell counts. Niraparib displayed a dose-dependent cytotoxic effect on both cell lines. Co-application of niraparib and TTFields resulted in enhanced cytotoxicity compared to the effect of niraparib or TTFields alone. TTFields also elevated the effects of niraparib on the colony-forming ability of the cells, the overall effect, and apoptosis. Conclusions: These results suggest a potential benefit for concomitant treatment of TTFields with niraparib in ovarian cancer. Additional experiments will examine the effect on the BRCA-FANC pathway in ovarian cancer. Objectives: PARP inhibition demonstrates clinical effectiveness in patients with solid tumors and deleterious BRCA mutations. The use of PARP inhibitors is specifically relevant in ovarian cancer, as one of three women with this malignancy harbor BRCA mutations. Tumor Treating Fields (TTFields) are alternating electric fields with antimitotic effects on cancerous cells, which are approved to treat patients with glioblastoma and malignant pleural mesothelioma. TTFields were shown to induce a state of BRCAness in several cancerous cell lines. The objective of this study was to explore the potential of combining TTFields with PARP inhibition for the treatment of ovarian cancer based on in vitro work. Methods: Ovarian carcinoma cells, A2780 (BRCA1/2 wild type) and OVCAR3 (BRCA1 wild type, BRCA2 mutated), were treated for 72 h with TTFields (at an intensity of 1.2 V/cm RMS and frequency of 200 kHz) using the in vitro system. The effectiveness of TTFields in combination with the PARP inhibitor niraparib was examined by measuring cell counts, clonogenic potential, overall effect (multiplicity product of cytotoxicity and clonogenicity), and apoptosis induction. Results: The application of TTFields to A2780 or OVCAR3 cells resulted in about 50% reduction in cell counts. Niraparib displayed a dose-dependent cytotoxic effect on both cell lines. Co-application of niraparib and TTFields resulted in enhanced cytotoxicity compared to the effect of niraparib or TTFields alone. TTFields also elevated the effects of niraparib on the colony-forming ability of the cells, the overall effect, and apoptosis. Conclusions: These results suggest a potential benefit for concomitant treatment of TTFields with niraparib in ovarian cancer. Additional experiments will examine the effect on the BRCA-FANC pathway in ovarian cancer.

Carbonic anhydrase XII as biomarker and therapeutic target in ovarian carcinomas.

Targeting the tumor-associated carbonic anhydrase XII (CA XII) is considered a promising strategy to improve cancer treatment. As such progress is highly demanded for ovarian carcinomas, the present study aimed to provide deeper information about their CA XII expression profile. A large collection of tissue specimens was stained immunohistochemically with a specific anti-CA XII antibody to evaluate the expression in neoplastic and non-neoplastic epithelial ovarian cells. In addition, flow cytometry was used to measure CA XII expression on tumor cells from malignant ascites fluid. Binding of the antibody revealed a significant CA XII expression in most ovarian carcinoma tissue samples and ascites-derived ovarian carcinoma cells. Moreover, CA XII was expressed at higher levels in ovarian carcinomas as compared to borderline ovarian tumors and non-neoplastic ovarian epithelia. Within the carcinoma tissues, high expression of CA XII was associated with higher tumor grading and a trend towards shorter overall survival. Our results indicate that CA XII plays a crucial role for the malignancy of ovarian carcinoma cells and emphasize the potential of CA XII as a diagnostic marker and therapeutic target in the management of ovarian carcinomas.

CBX8 Together with SET Facilitates Ovarian Carcinoma Growth and Metastasis by Suppressing the Transcription of SUSD2.

Our study uncovers a novel mechanism CBX8 explores to execute gene repression, and provides new therapeutic targets for ovarian carcinoma.

IFN-γ/Doxorubicin Complex Nanoparticles for Enhancing Therapy in the Context of Human Ovarian Carcinoma

The cytokine interferon gamma (IFN-γ) and doxorubicin mono-therapy has been approved by the Food and Drug Administration (FDA) for the treatment of tumors. The importance of IFN-γ in the immune system lies in its immunomodulatory effects, and the importance of doxorubicin in antitumor therapy lies in inhibiting RNA and DNA synthesis. In this work, the role of IFN-γ in the antitumor activity in combination with doxorubicin was investigated. Meanwhile, IFN-γ was used as a vehicle to load doxorubicin over immunotherapy and chemotherapy for synergistic therapy. IFN-γ/doxorubicin complex nanoparticles were prepared by a fusion method with a size of approximately 13 nm and a low polydispersity index. The doxorubicin release profile was analyzed with different pH ranges, and it showed an enhanced release in acidic pH. The ability of IFN-γ/doxorubicin complex nanoparticles to induce human ovarian carcinoma cell (Skov 3) apoptosis was evaluated by the cytotoxicity test. The cellular uptake of IFN-γ/doxorubicin complex nanoparticles was time-dependent, and the IFN-γ/doxorubicin complex nanoparticles showed a higher apoptosis efficiency than free doxorubicin by flow cytometry analysis and fluorescence imaging. This work bridged IFN-γ with doxorubicin to utilize their potential for antitumor activities, opening new avenues for their use in clinical settings.

Toward a Topology-Based Therapeutic Design of Membrane Proteins: Validation of NaPi2b Topology in Live Ovarian Cancer Cells.

NaPi2b is a sodium-dependent phosphate transporter that belongs to the SLC34 family of transporters which is mainly responsible for phosphate homeostasis in humans. Although NaPi2b is widely expressed in normal tissues, its overexpression has been demonstrated in ovarian, lung, and other cancers. A valuable set of antibodies, including L2 (20/3) and MX35, and its humanized versions react strongly with an antigen on the surface of ovarian and other carcinoma cells. Although the topology of NaPi2b was predicted in silico, no direct experimental data are available for the orientation of NaPi2b extracellular domains in cancer cells. The presented results of antibody mapping of untagged NaPi2b in live ovarian carcinoma cells OVCAR-4 provide a platform for current and future epitope-based cancer therapies and serological diagnostics.

Stable CDK12 Knock-Out Ovarian Cancer Cells Do Not Show Increased Sensitivity to Cisplatin and PARP Inhibitor Treatment.

Cyclin-dependent kinase 12 (CDK12) is a serine/threonine kinase involved in the regulation of RNA polymerase II and in the transcription of a subset of genes involved in the DNA damage response. CDK12 is one of the most mutated genes in ovarian carcinoma. These mutations result in loss-of-function and can predict the responses to PARP1/2 inhibitor and platinum. To investigate the role of CDK12 in ovarian cancer, CRISPR/Cas9 technology was used to generate a stable CDK12 knockout (KO) clone in A2780 ovarian carcinoma cells. This is the first report on a CDK12 null cell line. The clone had slower cell growth and was less clonogenic than parental cells. These data were confirmed in vivo, where CDK12 KO transplanted cells had a much longer time lag and slightly slower growth rate than CDK12-expressing cells. The slower growth was associated with a higher basal level of apoptosis, but there were no differences in the basal level of autophagy and senescence. While cell cycle distribution was similar in parental and knockout cells, there was a doubling in DNA content, with an almost double modal number of chromosomes in the CDK12 KO clone which, however did not display any increase in γH2AX, a marker of DNA damage. We found partial down-regulation of the expression of DNA repair genes at the mRNA level and, among the down-regulated genes, an enrichment in the G2/M checkpoint genes. Although the biological features of CDK12 KO cells are compatible with the function of CDK12, contrary to some reports, we could not find any difference in the sensitivity to cisplatin and olaparib between wild-type and CDK12 KO cells.

The activation of M2 muscarinic receptor inhibits cell growth and survival in human epithelial ovarian carcinoma.

Ovarian cancer is the fifth leading cause of cancer-related deaths in females. Many ovarian tumor cell lines express muscarinic receptors (mAChRs), and their expression is correlated with reduced survival of patients. We have characterized the expression of mAChRs in two human ovarian carcinoma cell lines (SKOV-3, TOV-21G) and two immortalized ovarian surface epithelium cell lines (iOSE-120, iOSE-398). Among the five subtypes of mAChRs (M1-M5 receptors), we focused our attention on the M2 receptor, which is involved in the inhibition of tumor cell proliferation. Western blot analysis and real-time PCR analyses indicated that the levels of M2 are statistically downregulated in cancer cells. Therefore, we investigated the effect of arecaidine propargyl ester hydrobromide (APE), a preferential M2 agonist, on cell growth and survival. APE treatment decreased cell number in a dose and time-dependent manner by decreasing cell proliferation and increasing cell death. FACS and immunocytochemistry analysis have also demonstrated the ability of APE to accumulate the cells in G2/M phase of the cell cycle and to increase the percentage of abnormal mitosis. The higher level of M2 receptors in the iOSE cells rendered these cells more sensitive to APE treatment than cancer cells. The data here reported suggest that M2 has a negative role in cell growth/survival of ovarian cell lines, and its downregulation may favor tumor progression.

Prognostic value of regulatory T cells and T helper 17 cells in high grade serous ovarian carcinoma

PurposeIn recent years the tumor microenvironment and its interaction with the tumor has emerged into research focus with increased attention to the composition of Tumor-infiltrating lymphocytes. We wanted to quantify the composition of Regulatory T cells (Tregs) and T helper 17 cells (Th17 cells) and their prognostic impact in high-grade serous tubo-ovarian carcinoma.MethodsTregs and Th17 cells were determined by immunohistochemical analysis of CD25 FoxP3 and RORγt, respectively on tissue microarrays of a cohort of 222 patients with reviewed histology and available clinical data. Expression was analyzed with Qupath for quantification and integration with clinical data enabled calculation of prognostic impact. For validation FOXP3 and RORC mRNA expression levels from 502 patients with HGSC in publicly available datasets were evaluated.ResultsAn average percentage of 0.93 Tregs and of 0.06 Th17 cells was detected per cells in overall tissue. Optimal cut-offs were determined and higher Tregs were associated with a better overall survival in stroma (p = 0.006), tumor area (p = 0.0012) and overall tissue (p = 0.02). After accounting for well-known prognostic factors age at diagnosis, residual tumor and FIGO stage, this association remained significant for stromal Tregs with overall survival (p = 0.02). Survival analysis for Th17 cells revealed no significant association with survival rates. Moreover, lower Th17/Treg ratios had a positive impact on patient overall survival (p = 0.025 tumor, p = 0.049 stroma and p = 0.016 overall tissue).ConclusionOur results outline a positive prognostic effect for higher Tregs but not for Th17 in high grade serous tubo-ovarian carcinoma.

Collision Tumor of the Ovary Involving Sertoli-Leydig Cell Tumor and High-Grade Serous Carcinoma-Report of the First Case.

We report a collision tumor in the ovary of a 60-yr-old woman composed of high-grade serous carcinoma and Sertoli-Leydig cell tumor. Collision tumors in the ovary are rare and to the best of our knowledge, combination of ovarian high-grade serous carcinoma and Sertoli-Leydig cell tumor has not been described before.

Anti-tumor and anti-metastatic activity of the FGF2 118-126 fragment dependent on the loop structure.

Fibroblast Growth Factor/FGF Receptor 1 (FGF2/FGFR1) system regulates the growth and metastasis of different cancers. Inhibition of this signaling pathway is an attractive target for cancer therapy. Here, we aimed to reproduce the 118-126 fragment of FGF2 to interfere with the FGF2-FGFR1 interaction. To determine whether the loop structure affects the function of this fragment, we compared cyclic (disulfide-bonded) and linear peptide variants. The cyclic peptide (referred to as BGF1) effectively inhibited the FGF2-induced proliferation of HUVECs, 4T1 mammary carcinoma, U87 glioblastoma, and SKOV3 ovarian carcinoma cells. It led to apoptosis induction in HUVECs, whereas the linear peptide (referred to as BGF2) was ineffective. In a murine 4T1 tumor model, BGF1 inhibited tumor growth more effectively than Avastin and increased animals' survival without causing weight loss, but the linear peptide BGF2 had no significant anti-tumor effects. According to immunohistochemical studies, the anti-tumor properties of BGF1 were associated with suppression of tumor cell proliferation (Ki-67 expression), angiogenesis (CD31 expression), and apoptosis induction (as was shown by increased p53 expression and TUNEL staining and decreased Bcl-2 expression). The potential of BGF1 to suppress tumor invasion was indicated by quantitative analysis of the metastasis-related proteins, including FGFR1, pFGFR1, NF-κB, p-NF-κB, MMP-9, E-cadherin, N-cadherin, and Vimentin, and supported by small animal positron emission tomography (PET) used 18Fluorodeoxyglucose (18F-FDG). These results demonstrate that the functional properties of the 118-126 region of FGF2 depend on the loop structure and the peptide derived from this fragment encourages further preclinical investigations.

Abstract LB542: Overexpression of the short isoform of Brd4 in ovarian carcinoma leads to highly aggressive tumor phenotype

Abstract High-grade serous ovarian carcinoma (HGSOC) is one of the deadliest types of cancer in the US. Occurrence of sporadic HGSOC is associated with high genomic instability, which causes amplification and deletion of several different genes. BRD4 is one of the most frequently amplified genes in ovarian carcinoma patients. BRD4 amplification leads to overexpression of BRD4 proteins including long and short BRD4 isoforms (BRD4-L and BRD4-S, respectively), and is associated with poor patient prognosis. Recently, it has been shown that the short isoform BRD4-S contributes to oncogenic properties of several tumor types; however, little is known about its role in ovarian cancer. Therefore, in order to interrogate the function of different BRD4 isoforms in HGSOC, we generated ovarian cancer cell lines stably overexpressing BRD4 isoforms (BRD4-L and BRD-S). Our data revealed that overexpression of BRD4-S in ovarian carcinoma cell lines induces a highly aggressive tumor phenotype in vitro and in vivo. Ovcar4-BRD4-S cells showed significantly higher cell proliferation rate and increased anchorage-independent growth when compared with parental cell lines. In addition, Ovcar4-BRD4-S presents a high level of DNA damage reflected by increased pH2AX foci. We also observed a disruption of cell cycle in Ovcar4-BRD4-S cells associated with a higher number of cells arrested in G2/M phase and increased population of polyploid cells. In vivo experiments demonstrated that BRD4-S expressing tumors grow significantly faster than parental tumors. BRD4-S overexpressing tumors are also very resistant to DNA-damage agents including standard of care platinum drugs. Finally, our preliminary drug screening demonstrated that Ovcar4-BRD4-S cells are highly sensitive to Wee1 inhibitor MK-1775. Furthermore, the combination of MK-1775 with paclitaxel synergistically increased the antitumor effect. In summary, our studies indicate that amplification of the BRD4 gene in HGSOC patients might lead to an increase in splicing of BRD4-S transcript, which in consequence promotes highly aggressive and platinum-resistant tumors. Precision therapies targeting BRD4 amplified tumors, such as Wee1 inhibitors in combination with paclitaxel hold great promise to improve ovarian cancer treatment and reduce chemotherapy resistance, which is a critical problem for eradication of this aggressive tumor. Citation Format: Ana Luiza Drumond-Bock, Luyao Wang, Lin Wang, Magdalena Cybula, Maria Rostworowska, Magdalena Bieniasz. Overexpression of the short isoform of Brd4 in ovarian carcinoma leads to highly aggressive tumor phenotype [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB542.

Abstract 1117: Investigating PD-1/PD-L1 checkpoint inhibition as a treatment for platinum-resistant ovarian cancer

Abstract Ovarian cancer is the deadliest cancer of the female reproductive system, with the majority of patients experiencing relapse on first-line platinum-based chemotherapies. Identifying potential targets for additional second-line therapies is critical for treating platinum-resistant ovarian cancer. To that end, the evolution of platinum resistance in a cell-based model of ovarian cancer was monitored via characterization of proteomic changes in cancer-derived extracellular vesicles (EVs) after progressive rounds of cisplatin treatment. The content of cancer-derived EVs was analyzed via reverse phase protein array, mass spectrometry, and Western blotting to identify pathways that could be targeted by second-line therapies. Several therapeutically relevant markers were upregulated, including phospho-EGFR (Y1068), multidrug transporter ABCE1, and PD-L1. Monoclonal antibody-based therapies (mAbs) targeting PD-1/PD-L1 have been deployed successfully as second-line treatments for a variety of cancers, but their success has yet to be translated to ovarian cancer. Current mAb-based immunotherapies suffer from several pitfalls including poor tissue penetration, a long-standing issue in ovarian cancer treatment. To offer an alternative to mAb-based immunotherapies, we developed a small interfering peptide consisting of a portion of the PD-L1 interface sequence. This lead peptide underwent several rounds of in silico optimization via molecular dynamics and modeling simulations to identify modifications that could improve affinity for PD-1 or stability in serum. When efficacy was assessed in vitro via Amplified Luminescent Proximity Homogeneous Assay screening, the modifications to the lead peptide were not shown to improve efficacy. However, serum stability studies indicated the modifications dramatically improved peptide stability, with detectable levels still quantifiable via mass spectrometry after 48 hours. The stabilized peptide, titled MN1.4, was chosen for further efficacy testing in cell-based models. A cisplatin-treated daughter line from the OVCAR8 high grade serous ovarian carcinoma cell line was created to model the effects of clinical platinum-based chemotherapy treatments on the most common ovarian cancer subtype. OVCAR8 cells were co-cultured in the presence of stimulated Jurkat T cells to measure markers of T cell activation, including IL-2, via ELISA after treatment with MN1.4 in the presence or absence of EVs derived from cisplatin-treated cells. This model allows for examination of the potential sensitization effects of first-line cisplatin treatment on PD-1/PD-L1 immunotherapy, and how cancer-derived EVs from cisplatin-treated cells can abrogate this effect. We conclude that exosomal PD-L1 may impair responses to PD-1/PD-L1 immunotherapy and should be considered when assessing the viability of this treatment option for ovarian cancer patients. Citation Format: Rachel Carter, Marissa Howard, James Erickson, Paul Russo, Alessandra Luchini, Amanda Haymond, Fatah Kashanchi, Mikell Paige, Lance Liotta. Investigating PD-1/PD-L1 checkpoint inhibition as a treatment for platinum-resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1117.

Abstract 2601: Concomitant treatment of ovarian cell lines with Tumor Treating Fields (TTFields) and PARP inhibitors

Abstract Background: PARP inhibitors (PARPi) are an effective treatment option for ovarian cancer patients harboring deleterious BRCA mutations. While such mutations prevail in one third of ovarian cancer patients, most of the other patients gain little survival benefit by the use of PARPi. Tumor Treating Fields (TTFields) are alternating electric fields with antimitotic effects on cancerous cells, also shown to induce a state of BRCAness in several types of cancer cell lines. The current study aimed to explore the potential of combining TTFields with PARP inhibition for the treatment of ovarian cancer in vitro. Methods: Ovarian carcinoma cells A2780 (BRCA1/2 wild type) and OVCAR3 (BRCA1 wild type, BRCA2 deep deletion) were treated with TTFields using the inovitro system. Treatment was applied for 72 h at an intensity of 1.2 V/cm RMS and frequency of 200 kHz. The efficacy of concomitant application of TTFields with the PARP inhibitors niraparib and olaparib was examined via measurements of cell survival, colony forming ability, overall effect (multiplicity product of cytotoxicity and clonogenicity), and apoptosis induction. Results: A2780 or OVCAR3 cells treated with TTFields displayed about 50% reduction in cell counts. Co-application of TTFields with PARPi enhanced the cytotoxic effect compared to that demonstrated by TTFields or PARPi alone. Concomitant application also resulted in reduced clonogenicity, enhanced overall effect, and increased apoptosis. Conclusions: The results suggest potential benefits for TTFields concomitant with PARP inhibiting agents for treatment of ovarian cancer. Citation Format: Antonia Martinez-Conde, Eyal Dor-On, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti. Concomitant treatment of ovarian cell lines with Tumor Treating Fields (TTFields) and PARP inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2601.

Insights of clinical significance from solid tumor profiles with FoundationOneCDx.

3126 Background: FoundationOne CDx (F1CDx) is a US FDA-approved companion diagnostic test to identify patients who may benefit from treatment in accordance with the approved therapeutic product labeling for 28 drug therapies. Tumor profiling with F1CDx detects genomic findings with evidence of additional clinical significance. This study analyzes the breadth and impact of clinical decision insights from F1CDx clinical reports across solid tumors. Methods: F1CDx consecutive reports (n = 109,695) were retrospectively analyzed for the type and frequency of clinically significant predictive, prognostic, and diagnostic genomic alterations and signatures in common cancer types and across solid tumors. Predictive markers were defined as therapeutically relevant markers in drug labels or NCCN guidelines or targets of ESCAT evidence Tier I/II (Mateo et al., 2018; PMID: 30137196). Prognostic and diagnostic markers were determined in accordance with NCCN, ESMO, or WHO guidelines. We also describe the frequency and targets of interventional clinical trials with targeted therapies or immune checkpoint inhibitors that were matched to tumor profiles based on clinical or strong preclinical evidence. Results: Predictive genomic findings of clinical significance were identified in more than half of non-small cell lung cancer (NSCLC), colorectal cancer (CRC), breast cancer (BC), and melanoma (MEL) tissue samples; over a third of ovarian cancer (OC), urothelial carcinoma (UC), and head and neck squamous cell carcinoma (HNSCC); approximately a fourth of prostate cancer (PC), gastro-esophageal adenocarcinoma (GEA), cholangiocarcinoma (CA), and glioma (GL) samples; and one in 18 pancreatic adenocarcinoma (PA) samples (Table). Prognostic markers were reported for patients with NSCLC (18%), CRC (10%), BC (16%), PC (25%), CA (8.1%), MEL (24%), GL (74%), or HNSCC (7.1%). Diagnostic markers were frequently detected for patients with GL and noted for patients with BC, GEA, or MEL (Table). Interventional clinical trials were evidence-matched to most F1CDx tumor profiles (89%, range 82% in PC to 99% in PA), with the targets of approved therapies accounting for a small subset of targets in clinical development. Conclusions: F1CDx reports support clinical decision making by interpreting predictive, prognostic, and diagnostic markers according to professional guidelines as well as investigational markers for the enrollment in clinical trials. [Table: see text]