CRISPR/Cas9-Mediated Trp53 and Brca2 Knockout to Generate Improved Murine Models of Ovarian High-Grade Serous Carcinoma

The Tie2 antagonist rebastinib reduces ovarian cancer growth in a syngeneic murine model

BACKGROUND

The receptor tyrosine kinase TIE2 and its ligands, angiopoietins (ANGPTs), promote angiogenesis. In addition to expression on vascular endothelial cells, TIE2 is expressed on M2-like pro-tumorigenic macrophages. Thus, the TIE2 inhibitor rebastinib was developed as a potential therapy to address multiple cancers. The objective of this study was to determine the effects of rebastinib alone and combined with chemotherapy in a syngeneic murine model of ovarian cancer.

METHODS

Female C57Bl6J mice were intraperitoneally injected with syngeneic ID8 ovarian cancer cells. Once tumors were established, mice were untreated (control) or treated with rebastinib, carboplatin plus paclitaxel (chemotherapy), or rebastinib plus chemotherapy. In one set of experiments, survival was followed for 140 days. In other experiments, ascites was harvested 24 h after the last treatment and analyzed by flow cytometry. In in vitro experiments, RNA sequencing was performed on ID8 cells and murine peritoneal macrophage cells (PMJ2R) after treatment with rebastinib, chemotherapy, or rebastinib plus chemotherapy.

RESULTS

Tumor-bearing mice treated with rebastinib plus chemotherapy had longer median survival than mice treated with chemotherapy (132.5 vs. 127 days, P < 0.01). Ascites from mice treated with rebastinib had more CD45 + macrophages (P < 0.03) and cytotoxic T cells (P < 0.0001) than ascites from mice treated with chemotherapy. Rebastinib had no significant effect on the numbers of regulatory T cells, Tie2 + macrophages, or Tie2 + M2 macrophages. In ID8 cells, in vitro, rebastinib treatment upregulated 1528 genes and downregulated 3115 genes. In macrophages, in vitro, rebastinib treatment upregulated 2302 genes and downregulated 2970 genes. Rebastinib differentially regulated ANGPT-like proteins in both types of cells, including several ANGPT-like genes involved in tumorigenesis, angiogenesis, and proliferation. ANGPTL1, an anti-angiogenic and anti-apoptotic gene, was increased tenfold in ID8 cells treated with rebastinib (P < 0.001) but was not altered in macrophages.

CONCLUSIONS

Rebastinib plus chemotherapy extends survival in a syngeneic murine model of ovarian cancer. Rebastinib alters proportions of immune cell subsets, increases cytotoxic T cells in ascites, and alters gene expression in tumor cells and macrophages.

The chemokine CX3CL1 promotes intraperitoneal tumour growth despite enhanced T-cell recruitment in ovarian cancer

T-cell recruiting chemokines are required for a successful immune intervention in ovarian cancer, and also for the efficacy of modern anticancer agents such as PARP inhibitors. The chemokine CX3CL1 recruits tumour-suppressive T-cells into solid tumours, but also mediates cell-cell adhesions, e.g. of tumour cells, through its membrane-bound form. So far, its role in ovarian cancer has only been rudimentarily addressed. We show that high CX3CL1 expression significantly correlates with worsened survival in human high-grade serous ovarian cancer (n=219). In preclinical ovarian cancer, CX3CL1 plays a dual role, as it enhances the adaptive anti-tumour response, but overall still promotes tumour growth, the latter as a feature of the intraperitoneal environment. Moreover, PARP inhibitors are able to increase CX3CL1 release from human ovarian cancer cells. Collectively, our study shows that CX3CL1 is a driver of intraperitoneal tumour growth in ovarian cancer, a feature that may compromise the anticancer effect of CX3CL1-inducing PARP inhibitors.

SMARCA4 regulates the NK-mediated killing of senescent cells

Induction of senescence by chemotherapeutic agents arrests cancer cells and activates immune surveillance responses to contribute to therapy outcomes. In this investigation, we searched for ways to enhance the NK-mediated elimination of senescent cells. We used a staggered screen approach, first identifying siRNAs potentiating the secretion of immunomodulatory cytokines to later test for their ability to enhance NK-mediated killing of senescent cells. We identified that genetic or pharmacological inhibition of SMARCA4 enhanced senescent cell elimination by NK cells. SMARCA4 expression is elevated during senescence and its inhibition derepresses repetitive elements, inducing the SASP via activation of cGAS/STING and MAVS/MDA5 pathways. Moreover, a PROTAC targeting SMARCA4 synergized with cisplatin to increase the infiltration of CD8 T cells and mature, activated NK cells in an immunocompetent model of ovarian cancer. Our results indicate that SMARCA4 inhibitors enhance NK-mediated surveillance of senescent cells and may represent senotherapeutic interventions for ovarian cancer.

Implication of fibroblast growth factor 7 in ovarian cancer metastases and patient survival

Background/Objectives

Patients with ovarian cancer commonly experience metastases and recurrences, which contribute to high mortality. Our objective was to better understand ovarian cancer metastasis and identify candidate biomarkers and drug targets for predicting and preventing ovarian cancer recurrence.

Methods

Transcripts of 770 cancer-associated genes were compared in cells collected from ascitic fluid versus resected tumors of an ES-2 orthotopic ovarian cancer mouse model. Associated cell types and pathways were explored with bioinformatics. FGF7 protein was measured using capillary-based immunoassays or ELISA in mouse and clinical specimens. Significances of differential gene expression and patient prognosis were determined by volcano plot and log-rank test, respectively.

Results

Tumor transcriptomes exhibited higher endothelial cells, oxygenation, proteasome activity, and metabolism in comparison to ascites, but similar percentages of cancer-associated fibroblasts and immune cells. FGF7 mRNA was significantly higher in mouse tumors compared to ascites. FGF7 protein was significantly higher in tumors than in ascites in independent mouse models and clinical specimens. Serum FGF7 protein levels above the median of 25 patients with ovarian cancer were associated with worse progression-free and overall survival (p = 0.005 and 0.019, respectively) independent of patient and tumor characteristics.

Conclusions

In comparison to ascites, tumors exhibit different transcriptomic profiles that identify candidate biomarkers and drug targets for predicting and preventing recurrence. Among these, elevated tumoral FGF7 validated at the protein level and elevated serum FGF7 were significantly associated with worse patient survival. These results support further development of FGF7 receptor-targeted drugs and serum FGF7 to prevent and predict recurrence, respectively.

EHMT1/2 Inhibition Promotes Regression of Therapy-Resistant Ovarian Cancer Tumors in a CD8 T-cell-Dependent Manner

Poly ADP-ribose polymerase inhibitors (PARPi) are first-line maintenance therapy for ovarian cancer and an alternative therapy for several other cancer types. However, PARPi-resistance is rising, and there is currently an unmet need to combat PARPi-resistant tumors. Here, we created an immunocompetent, PARPi-resistant mouse model to test the efficacy of combinatory PARPi and euchromatic histone methyltransferase 1/2 inhibitor (EHMTi) in the treatment of PARPi-resistant ovarian cancer. We discovered that inhibition of EHMT1/2 resensitizes cells to PARPi. Markedly, we show that single EHMTi and combinatory EHMTi/PARPi significantly reduced PARPi-resistant tumor burden and that this reduction is partially dependent on CD8 T cells. Altogether, our results show a low-toxicity drug that effectively treats PARPi-resistant ovarian cancer in an immune-dependent manner, supporting its entry into clinical development and potential incorporation of immunotherapy. Implications: Targeting the epigenome of therapy-resistant ovarian cancer induces an antitumor response mediated in part through an antitumor immune response.

Myeloid activation clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of <30% due to the persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of β-glucan and IFNγ (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. β-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

Characterization of DNA damage repair pathway utilization in high-grade serous ovarian cancers yields rational therapeutic approaches

While poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have improved the prognosis of ovarian high-grade serous carcinoma (HGSC) tumors that are homologous recombination (HR) deficient (HRD), new therapeutic strategies are needed for tumors that are HR proficient (HRP) because they demonstrate greater resistance to current treatments and thus have poorer clinical outcomes. Additionally, clinical precautionary statements regarding potential risks associated with PARPi, such as myelodysplastic syndrome, highlight the need for combinatorial approaches that can lessen the dose and duration of PARPi treatment to reduce toxicities. Here, we evaluated DNA double-strand damage repair pathways in HRD and HRP ovarian cancer cell lines and found that in HRD cell lines, PARPi therapy reduced non-homologous end joining (NHEJ)-mediated repair, specifically due to decreased theta-mediated end-joining. The combination of PARPi with ATM serine/threonine kinase inhibitor (ATMi) suppressed both NHEJ and HR pathways in HRD and HRP cell lines, with synergistic increases in apoptosis and decreases in cell viability and colony formation. Interestingly, PARPi plus ATMi also decreased NF-κB p65 phosphorylation, which was not observed when PARPi was combined with inhibition of the ATR kinase (ATRi). These findings indicate that PARPi plus ATMi is a promising strategy for HGSC independent of underlying tumor HR status.

USP1 deubiquitinates PARP1 to regulate its trapping and PARylation activity

PARP inhibitors (PARPi) represent a game-changing treatment for patients with ovarian cancer with tumors deficient for the homologous recombination (HR) pathway treated with platinum (Pt)-based therapy. PARPi exert their cytotoxic effect by both trapping PARP1 on the damaged DNA and by restraining its enzymatic activity (PARylation). How PARP1 is recruited and trapped at the DNA damage sites and how resistance to PARPi could be overcome are still matters of investigation. Here, we described PARP1 as a substrate of the deubiquitinase USP1. At molecular level, USP1 binds PARP1 to remove its K63-linked polyubiquitination and controls PARP1 chromatin trapping and PARylation activity, regulating sensitivity to PARPi. In both Pt/PARPi-sensitive and -resistant cells, USP1/PARP1 combined blockade enhances replicative stress, DNA damage, and cell death. Our work dissected the biological interaction between USP1 and PARP1 and recommended this axis as a promising and powerful therapeutic choice for not only sensitive but also chemoresistant patients with ovarian cancer irrespective of their HR status.

PTEN Loss Shapes Macrophage Dynamics in High-Grade Serous Ovarian Carcinoma

High-grade serous ovarian carcinoma (HGSC) remains a disease with poor prognosis that is unresponsive to current immune checkpoint inhibitors. Although PI3K pathway alterations, such as PTEN loss, are common in HGSC, attempts to target this pathway have been unsuccessful. We hypothesized that aberrant PI3K pathway activation may alter the HGSC immune microenvironment and present a targeting opportunity. Single-cell RNA sequencing identified populations of resident macrophages specific to Pten-null omental tumors in murine models, which were confirmed by flow cytometry. These macrophages were derived from peritoneal fluid macrophages and exhibited a unique gene expression program, marked by high expression of the enzyme heme oxygenase-1 (HMOX1). Targeting resident peritoneal macrophages prevented the appearance of HMOX1hi macrophages and reduced tumor growth. In addition, direct inhibition of HMOX1 extended survival in vivo. RNA sequencing identified IL33 in Pten-null tumor cells as a likely candidate driver, leading to the appearance of HMOX1hi macrophages. Human HGSC tumors also contained HMOX1hi macrophages with a corresponding gene expression program. Moreover, the presence of these macrophages was correlated with activated tumoral PI3K/mTOR signaling and poor overall survival in patients with HGSC. In contrast, tumors with low numbers of HMOX1hi macrophages were marked by increased adaptive immune response gene expression. These data suggest targeting HMOX1hi macrophages as a potential therapeutic strategy for treating poor prognosis HGSC. Significance: Macrophages with elevated HMOX1 expression are enriched in PTEN-deficient high-grade serous ovarian carcinoma, promote tumor growth, and represent a potential therapeutic target.

Egfl6 promotes ovarian cancer progression by enhancing the immunosuppressive functions of tumor-associated myeloid cells

Tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs) play a critical role in resistance to immunotherapy. In this study, we identified epidermal growth factor-like 6 (Egfl6) as a regulator of myeloid cell functions. Our analyses indicated that Egfl6, via binding with β3 integrins and activation of p38 and SYK signaling, acts as a chemotactic factor for myeloid cell migration and promotes their differentiation toward an immunosuppressive state. In syngeneic mouse models of ovarian cancer (OvCa), tumor expression of Egfl6 increased the intratumoral accumulation of polymorphonuclear (PMN) MDSCs and TAMs and their expression of immunosuppressive factors, including CXCL2, IL-10, and PD-L1. Consistent with this, in an immune 'hot' tumor model, Egfl6 expression eliminated response to anti-PD-L1 therapy, while Egfl6 neutralizing antibody decreased the accumulation of tumor-infiltrating CD206+ TAMs and PMN-MDSCs and restored the efficacy of anti-PD-L1 therapy. Supporting a role in human tumors, in human OvCa tissue samples, areas of high EGFL6 expression colocalized with myeloid cell infiltration. scRNA-Seq analyses revealed a correlation between EGFL6 and immune cell expression of immunosuppressive factors. Our data provide mechanistic insights into the oncoimmunologic functions of EGFL6 in mediating tumor immune suppression and identified EGFL6 as a potential therapeutic target to enhance immunotherapy in patients with OvCa.

Combination non-targeted and sGRP78-targeted nanoparticle drug delivery outperforms either component to treat metastatic ovarian cancer

Metastatic ovarian cancer (MOC) is highly deadly, due in part to the limited efficacy of standard-of-care chemotherapies to metastatic tumors and non-adherent cancer cells. Here, we demonstrated the effectiveness of a combination therapy of GRP78-targeted (TNPGRP78pep) and non-targeted (NP) nanoparticles to deliver a novel DM1-prodrug to MOC in a syngeneic mouse model. Cell surface-GRP78 is overexpressed in MOC, making GRP78 an optimal target for selective delivery of nanoparticles to MOC. The NP + TNPGRP78pep combination treatment reduced tumor burden by 15-fold, compared to untreated control. Increased T cell and macrophage levels in treated groups also suggested antitumor immune system involvement. The NP and TNPGRP78pep components functioned synergistically through two proposed mechanisms of action. The TNPGRP78pep targeted non-adherent cancer cells in the peritoneal cavity, preventing the formation of new solid tumors, while the NP passively targeted existing solid tumor sites, providing a sustained release of the drug to the tumor microenvironment.

Acetate drives ovarian cancer quiescence via ACSS2-mediated acetyl-CoA production

Quiescence is a reversible cell cycle exit traditionally thought to be associated with a metabolically inactive state. Recent work in muscle cells indicates that metabolic reprogramming is associated with quiescence. Whether metabolic changes occur in cancer to drive quiescence is unclear. Using a multi-omics approach, we found that the metabolic enzyme ACSS2, which converts acetate into acetyl-CoA, is both highly upregulated in quiescent ovarian cancer cells and required for their survival. Indeed, quiescent ovarian cancer cells have increased levels of acetate-derived acetyl-CoA, confirming increased ACSS2 activity in these cells. Furthermore, either inducing ACSS2 expression or supplementing cells with acetate was sufficient to induce a reversible quiescent cell cycle exit. RNA-Seq of acetate treated cells confirmed negative enrichment in multiple cell cycle pathways as well as enrichment of genes in a published G0 gene signature. Finally, analysis of patient data showed that ACSS2 expression is upregulated in tumor cells from ascites, which are thought to be more quiescent, compared to matched primary tumors. Additionally, high ACSS2 expression is associated with platinum resistance and worse outcomes. Together, this study points to a previously unrecognized ACSS2-mediated metabolic reprogramming that drives quiescence in ovarian cancer. As chemotherapies to treat ovarian cancer, such as platinum, have increased efficacy in highly proliferative cells, our data give rise to the intriguing question that metabolically-driven quiescence may affect therapeutic response.

Ablation of hematopoietic stem cell derived adipocytes reduces tumor burden in syngeneic mouse models of high-grade serous carcinoma

In this study we examined the influence of hematopoietic stem cell-derived adipocytes (HSCDAs) on the proliferation and metastasis of high-grade serous carcinoma (HGSC) - the most common type of ovarian cancer. HSCDAs are a subtype of adipocytes that differentiate from myeloid precursors that traffic from bone marrow to adipose tissue and accumulate therein. These are distinct from conventional mesenchymal adipocytes (CMAs), which are derived from mesenchymal precursors. We hypothesized that HSCDAs promote HGSC progression and establish a pro-tumoral niche within peritoneal adipose tissues such as the omentum. Primary human white adipose tissue samples were obtained via biopsy and then sorted into myeloid and mesenchymal populations through flow cytometry. These adipose precursors were then differentiated in vitro into mature HSCDAs and CMAs, respectively. Transcriptomic analysis showed that HSCDAs have a distinct transcriptional profile from CMAs, including downregulation of cell cycle and upregulation of multiple metabolic and adipogenic pathways. Using ELISA, we found that HSCDAs secreted greater amounts of inflammatory cytokines IL-6 and IL-8 than CMAs. Next, we incubated HGSC cells in conditioned media from HSCDAs and CMAs and performed proliferation and protein expression profiling. HGSC cells in HSCDA media, compared to those in CMA media, had elevated expression of protein markers related to epithelial to mesenchymal plasticity, including fibronectin, as well as increased serine phosphorylation of pro-survival AKT1/2. Conversely, HGSC cells in HSCDA media exhibited comparably downregulated expression of tumor suppressors including the Wnt regulator GSK3β. Depending on the cell line and adipose donor, HGSC cells also showed altered growth rates in conditioned media. We next investigated the role of HSCDAs in HGSC progression and metastasis in vivo . We generated immunocompetent mice that were either HSCDA Proficient (can make both adipocyte subtypes) or Deficient (can only make CMAs). Using these models, we conducted two independent tumor studies using the ID8 ( Tp53-/- , Brca2-/- ) and SO ( Tp53-/- , Brca1/2 wild-type, Hras and Myc amplified) syngeneic models. Overall tumor burden was lower in HSCDA Deficient mice in both models. In the ID8 model, omental tumors from HSCDA Deficient mice showed reduced proliferation (Ki67) and apoptosis (cleaved caspase 3) relative to those from Proficient mice. Transcriptionally, omental ID8 tumors from HSCDA Deficient downregulated oxidative phosphorylation, adipogenesis, and fatty acid metabolism relative to tumors from HSCDA Proficient mice. These pathways were enriched in HSCDA cells in vitro , suggesting that ablation of HSCDAs had a significant influence on the tumor metabolic environment. Reduced inflammatory pathways in ID8 tumors from HSCDA Deficient mice were also observed leading us to interrogate immune cell infiltration into omental tumors. Compared to HSCDA Proficient mice, tumors from HSCDA Deficient mice showed reduced densities of dendritic cells (DC) and natural killer (NK) cells, as well as fewer DCs, NKs, and B-cells in proximity to tumor cells, as determined by spatial analysis. Overall, our data suggest that HSCDAs promote HGSC survival and plasticity while downregulating expression of tumor suppressors and altering the peritoneal immune and metabolic environment to promote HGSC progression.

Neoadjuvant PARPi or chemotherapy in ovarian cancer informs targeting effector Treg cells for homologous-recombination-deficient tumors

Homologous recombination deficiency (HRD) is prevalent in cancer, sensitizing tumor cells to poly (ADP-ribose) polymerase (PARP) inhibition. However, the impact of HRD and related therapies on the tumor microenvironment (TME) remains elusive. Our study generates single-cell gene expression and T cell receptor profiles, along with validatory multimodal datasets from >100 high-grade serous ovarian cancer (HGSOC) samples, primarily from a phase II clinical trial (NCT04507841). Neoadjuvant monotherapy with the PARP inhibitor (PARPi) niraparib achieves impressive 62.5% and 73.6% response rates per RECIST v.1.1 and GCIG CA125, respectively. We identify effector regulatory T cells (eTregs) as key responders to HRD and neoadjuvant therapies, co-occurring with other tumor-reactive T cells, particularly terminally exhausted CD8+ T cells (Tex). TME-wide interferon signaling correlates with cancer cells upregulating MHC class II and co-inhibitory ligands, potentially driving Treg and Tex fates. Depleting eTregs in HRD mouse models, with or without PARP inhibition, significantly suppresses tumor growth without observable toxicities, underscoring the potential of eTreg-focused therapeutics for HGSOC and other HRD-related tumors.

Advances in delivery systems for CRISPR/Cas-mediated cancer treatment: a focus on viral vectors and extracellular vesicles

The delivery of CRISPR/Cas systems holds immense potential for revolutionizing cancer treatment, with recent advancements focusing on extracellular vesicles (EVs) and viral vectors. EVs, particularly exosomes, offer promising opportunities for targeted therapy due to their natural cargo transport capabilities. Engineered EVs have shown efficacy in delivering CRISPR/Cas components to tumor cells, resulting in inhibited cancer cell proliferation and enhanced chemotherapy sensitivity. However, challenges such as off-target effects and immune responses remain significant hurdles. Viral vectors, including adeno-associated viruses (AAVs) and adenoviral vectors (AdVs), represent robust delivery platforms for CRISPR/Cas systems. AAVs, known for their safety profile, have already been employed in clinical trials for gene therapy, demonstrating their potential in cancer treatment. AdVs, capable of infecting both dividing and non-dividing cells, offer versatility in CRISPR/Cas delivery for disease modeling and drug discovery. Despite their efficacy, viral vectors present several challenges, including immune responses and off-target effects. Future directions entail refining delivery systems to enhance specificity and minimize adverse effects, heralding personalized and effective CRISPR/Cas-mediated cancer therapies. This article underscores the importance of optimized delivery mechanisms in realizing the full therapeutic potential of CRISPR/Cas technology in oncology. As the field progresses, addressing these challenges will be pivotal for translating CRISPR/Cas-mediated cancer treatments from bench to bedside.

Immunogenomic profiles and therapeutic options of the pan-programmed cell death-related lncRNA signature for patients with bladder cancer

Programmed cell death (PCD) is a process that eliminates infected, damaged, or possibly neoplastic cells to sustain homeostatic multicellular organisms. Although long noncoding RNAs (lncRNAs) are involved in various types of PCD and regulate tumor growth, invasion, and migration, the role of PCD-related lncRNAs in bladder cancer still lacks systematic exploration. In this research, we integrated multiple types of PCD as pan-PCD and identified eight pan-PCD-related lncRNAs (LINC00174, HCP5, HCG27, UCA1, SNHG15, GHRLOS, CYB561D2, and AGAP11). Then, we generated a pan-PCD-related lncRNA prognostic signature (PPlncPS) with excellent predictive power and reliability, which performed equally well in the E-MTAB-4321 cohort. In comparison with the low-PPlncPS score group, the high-PPlncPS score group had remarkably higher levels of angiogenesis, matrix, cancer-associated fibroblasts, myeloid cell traffic, and protumor cytokine signatures. In addition, the low-PPlncPS score group was positively correlated with relatively abundant immune cell infiltration, upregulated expression levels of immune checkpoints, and high tumor mutation burden (TMB). Immunogenomic profiles revealed that patients with both low PPlncPS scores and high TMB had the best prognosis and may benefit from immune checkpoint inhibitors. Furthermore, for patients with high PPlncPS scores, docetaxel, staurosporine, and luminespib were screened as potential therapeutic candidates. In conclusion, we generated a pan-PCD-related lncRNA signature, providing precise and individualized prediction for clinical prognosis and some new insights into chemotherapy and immune checkpoint inhibitor therapy for bladder cancer.

BRCA Status Dictates Wnt Responsiveness in Epithelial Ovarian Cancer

The association of BRCA1 and BRCA2 mutations with increased risk for developing epithelial ovarian cancer is well established. However, the observed clinical differences, particularly the improved therapy response and patient survival in BRCA2-mutant patients, are unexplained. Our objective is to identify molecular pathways that are differentially regulated upon the loss of BRCA1 and BRCA2 functions in ovarian cancer. Transcriptomic and pathway analyses comparing BRCA1-mutant, BRCA2-mutant, and homologous recombination wild-type ovarian tumors showed differential regulation of the Wnt/β-catenin pathway. Using Wnt3A-treated BRCA1/2 wild-type, BRCA1-null, and BRCA2-null mouse ovarian cancer cells, we observed preferential activation of canonical Wnt/β-catenin signaling in BRCA1/2 wild-type ovarian cancer cells, whereas noncanonical Wnt/β-catenin signaling was preferentially activated in the BRCA1-null ovarian cancer cells. Interestingly, BRCA2-null mouse ovarian cancer cells demonstrated a unique response to Wnt3A with the preferential upregulation of the Wnt signaling inhibitor Axin2. In addition, decreased phosphorylation and enhanced stability of β-catenin were observed in BRCA2-null mouse ovarian cancer cells, which correlated with increased inhibitory phosphorylation on GSK3β. These findings open venues for the translation of these molecular observations into modalities that can impact patient survival.

SIGNIFICANCE

We show that BRCA1 and BRCA2 mutation statuses differentially impact the regulation of the Wnt/β-catenin signaling pathway, a major effector of cancer initiation and progression. Our findings provide a better understanding of molecular mechanisms that promote the known differential clinical profile in these patient populations.

Tumor-Intrinsic Activity of Chromobox 2 Remodels the Tumor Microenvironment in High-grade Serous Carcinoma

Chromobox 2 (CBX2), an epigenetic reader and component of polycomb repressor complex 1, is highly expressed in >75% of high-grade serous carcinoma. Increased CBX2 expression is associated with poorer survival, whereas CBX2 knockdown leads to improved chemotherapy sensitivity. In a high-grade serous carcinoma immune-competent murine model, knockdown of CBX2 decreased tumor progression. We sought to explore the impact of modulation of CBX2 on the tumor immune microenvironment (TIME), understanding that the TIME plays a critical role in disease progression and development of therapy resistance. Exploration of existing datasets demonstrated that elevated CBX2 expression significantly correlated with specific immune cell types in the TIME. RNA sequencing and pathway analysis of differentially expressed genes demonstrated immune signature enrichment. Confocal microscopy and co-culture experiments found that modulation of CBX2 leads to increased recruitment and infiltration of macrophages. Flow cytometry of macrophages cultured with CBX2-overexpressing cells showed increased M2-like macrophages and decreased phagocytosis activity. Cbx2 knockdown in the Trp53-null, Brca2-null ID8 syngeneic murine model (ID8 Trp53-/-Brca2-/-) led to decreased tumor progression compared with the control. NanoString immuno-oncology panel analysis suggested that knockdown in Cbx2 shifts immune cell composition, with an increase in macrophages. Multispectral immunohistochemistry (mIHC) further confirmed an increase in macrophage infiltration. Increased CBX2 expression leads to recruitment and polarization of protumor macrophages, and targeting CBX2 may serve to modulate the TIME to enhance the efficacy of immune therapies.

SIGNIFICANCE

CBX2 expression correlates with the TIME. CBX2 modulation shifts the macrophage population, potentially leading to an immunosuppressive microenvironment, highlighting CBX2 as a target to improve efficacy of immunotherapy.

Adipose microenvironment promotes hypersialylation of ovarian cancer cells

Introduction

Ovarian and other peritoneal cancers have a strong tendency to metastasize into the surrounding adipose tissue. This study describes an effect of the adipose microenvironment on upregulation of sialic acid-containing glycans in ovarian cancer (OC). Heterogeneous populations of glycosylated OC tumors converged to a highly sialylated cell state that regulates tumorigenesis in an immune-dependent manner.

Methods

We modeled the adipose microenvironment by conditioning growth media with human patient-derived adipose tissue. OC cell lines grown in the presence vs. absence of adipose conditioned media (ACM) were characterized by transcriptomics, western blotting, and chemical biology glycan labeling methods. Fluorescence-activated cell sorting was used to separate adipose-driven upregulation of hypersialylated ("SNA-high") vs. hyposialylated ("SNA-low") OC subpopulations. The two subpopulations were characterized by further transcriptomic and quantitative polymerase chain reaction analyses, then injected into a syngeneic mouse model. Immune system involvement was implicated using wild type and athymic nude mice with a primary endpoint of overall survival.

Results

Adipose conditioning resulted in upregulation of sialyltransferases ST3GAL1, ST6GAL1, ST6GALNAC3, and ST8Sia1. In culture, OC cells displayed two distinct sialylated subpopulations that were stable for up to 9 passages, suggesting inherent heterogeneity in sialylation that is maintained throughout cell division and media changes. OC tumors that implanted in the omental adipose tissue exclusively reprogrammed to the highly sialylated subpopulation. In wild type C57BL/6 mice, only the hypersialylated SNA-high subpopulation implanted in the adipose, whereas the hyposialylated SNA-low subpopulation failed to be tumorigenic (p=0.023, n=5). In the single case where SNA-low established a tumor, post-mortem analysis revealed reprogramming of the tumor to the SNA-high state in vivo. In athymic nude mice, both subpopulations rapidly formed tumors, implicating a role of the adaptive immune system.

Conclusions

These findings suggest a model of glycan-dependent tumor evolution wherein the adipose microenvironment reprograms OC to a tumorigenic state that resists the adaptive immune system. Mechanistically, adipose factors upregulate sialyltransferases. To our knowledge, this is the first demonstration of the effect of adipose microenvironment on OC tumor sialylation. Our results set the stage for translational applications targeting sialic acid pathways in OC and other peritoneal cancer tumorigenesis and metastasis.

Nonviral CRISPR/Cas9 mutagenesis for streamlined generation of mouse lung cancer models

Functional analysis in mouse models is necessary to establish the involvement of a set of genetic variations in tumor development. A modeling platform to facilitate and cost-effectively analyze the role of multiple genes in carcinogenesis would be valuable. Here, we present an innovative strategy for lung mutagenesis using CRISPR/Cas9 ribonucleoproteins delivered via cationic polymers. This approach allows the simultaneous inactivation of multiple genes. We validate the effectiveness of this system by targeting a group of tumor suppressor genes, specifically Rb1, Rbl1, Pten, and Trp53, which were chosen for their potential to cause lung tumors, namely small cell lung carcinoma (SCLC). Tumors with histologic and transcriptomic features of human SCLC emerged after intratracheal administration of CRISPR/polymer nanoparticles. These tumors carried loss-of-function mutations in all four tumor suppressor genes at the targeted positions. These findings were reproduced in two different pure genetic backgrounds. We provide a proof of principle for simplified modeling of lung tumorigenesis to facilitate functional testing of potential cancer-related genes.

Monocyte infiltration is an independent positive prognostic biomarker in vulvar squamous cell carcinoma

BACKGROUND

Vulvar squamous cell carcinoma (VSCC) arises after an HPV infection or the mutation of p53 or other driver genes and is treated by mutilating surgery and/or (chemo) radiation, with limited success and high morbidity. In-depth information on the immunological make up of VSCC is pivotal to assess whether immunotherapy may form an alternative treatment.

METHODS

A total of 104 patient samples, comprising healthy vulva (n = 27) and VSCC (n = 77), were analyzed. Multispectral immunofluorescence (15 markers) was used to study both the myeloid and lymphoid immune cell composition, and this was linked to differences in transcriptomics (NanoString nCounter, 1258 genes) and in survival (Kaplan-Meier analyses).

RESULTS

Healthy vulva and VSCC are both well infiltrated but with different subpopulations of lymphoid and myeloid cells. In contrast to the lymphoid cell infiltrate, the density and composition of the myeloid cell infiltrate strongly differed per VSCC molecular subtype. A relative strong infiltration with epithelial monocytes (HLADR-CD11c-CD14+CD68-CD163-CD33-) was prognostic for improved survival, independent of T cell infiltration, disease stage or molecular subtype. A strong infiltration with T cells and/or monocytes was associated with drastic superior survival: 5-year survival > 90% when either one is high, versus 40% when both are low (p < 0.001).

CONCLUSION

A hot myeloid and/or lymphoid infiltrate predicts excellent survival in VSCC. Based on the response of similarly high-infiltrated other tumor types, we have started to explore the potential of neoadjuvant checkpoint blockade in VSCC.

Intraperitoneal activation of myeloid cells clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of less than 30% due to persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of β-glucan and IFNγ (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. β-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

Genomic profiling informs therapies and prognosis for patients with hepatocellular carcinoma in clinical practice

Hepatocellular carcinoma (HCC) genomic research has discovered actionable genetic changes that might guide treatment decisions and clinical trials. Nonetheless, due to a lack of large-scale multicenter clinical validation, these putative targets have not been converted into patient survival advantages. So, it's crucial to ascertain whether genetic analysis is clinically feasible, useful, and whether it can be advantageous for patients. We sequenced tumour tissue and blood samples (as normal controls) from 111 Chinese HCC patients at Qingdao University Hospital using the 508-gene panel and the 688-gene panel, respectively. Approximately 95% of patients had gene variations related to targeted treatment, with 50% having clinically actionable mutations that offered significant information for targeted therapy. Immune cell infiltration was enhanced in individuals with TP53 mutations but decreased in patients with CTNNB1 and KMT2D mutations. More notably, we discovered that SPEN, EPPK1, and BRCA2 mutations were related to decreased median overall survival, although MUC16 mutations were not. Furthermore, we found mutant MUC16 as an independent protective factor for the prognosis of HCC patients after curative hepatectomy. In conclusion, this study connects genetic abnormalities to clinical practice and potentially identifies individuals with poor prognoses who may benefit from targeted treatment or immunotherapy.

Blockade of TGF-β and PD-L1 by bintrafusp alfa promotes survival in preclinical ovarian cancer models by promoting T effector and NK cell responses

BACKGROUND

Failure of immunotherapy in high-grade serous ovarian cancer (HGSC) may be due to high levels of transforming growth factor-β (TGF-β) in ascites or tumour immune microenvironment (TIME). Here, we test whether coordinated blockade of TGF-β and PD-L1 with bintrafusp alfa (BA) can provoke anti-tumour immune responses in preclinical HGSC models.

METHODS

BA is a first-in-class bifunctional inhibitor of TGF-β and PD-L1, and was tested for effects on overall survival and altered TIME in syngeneic HGSC models.

RESULTS

Using a mouse ID8-derived HGSC syngeneic model with IFNγ-inducible PD-L1 expression, BA treatments significantly reduced ascites development and tumour burden. BA treatments depleted TGF-β and VEGF in ascites, and skewed the TIME towards cytotoxicity compared to control. In the BR5 HGSC syngeneic model, BA treatments increased tumour-infiltrating CD8 T cells with effector memory and cytotoxic markers, as well as cytolytic NK cells. Extended BA treatments in the BR5 model produced ∼50% BA-cured mice that were protected from re-challenge. These BA-cured mice had increased peritoneal T-effector memory and NK cells compared to controls.

CONCLUSIONS

Our preclinical studies of BA in advanced ovarian cancer models support further testing of BA as an improved immunotherapy option for patients with advanced ovarian cancer.

Adipose microenvironment promotes hypersialylation of ovarian cancer cells

Sialylation, the addition of negatively charged sialic acid sugars to terminal ends of glycans, is upregulated in most cancers. Hypersialylation supports multiple pro-tumor mechanisms such as enhanced migration and invasion, resistance to apoptosis and immune evasion. A current gap in knowledge is the lack of understanding on how the tumor microenvironment regulates cancer cell sialylation. The adipose niche is a main component of most peritoneal cancers' microenvironment. This includes ovarian cancer (OC), which causes most deaths from all gynecologic cancers. In this report, we demonstrate that the adipose microenvironment is a critical regulator of OC cell sialylation. In vitro adipose conditioning led to an increase in both ⍺2,3- and ⍺2,6-linked cell surface sialic acids in both human and mouse models of OC. Adipose-induced sialylation reprogramming was also observed in vivo from intra-peritoneal OC tumors seeded in the adipose-rich omentum. Mechanistically, we observed upregulation of at least three sialyltransferases, ST3GAL1, ST6GAL1 and ST3GALNAC3. Hypersialylated OC cells consistently formed intra-peritoneal tumors in both immune-competent mice and immune-compromised athymic nude mice. In contrast, hyposiaylated OC cells persistently formed tumors only in athymic nude mice demonstrating that sialylation impacts OC tumor formation in an immune dependent manner. To our knowledge, this is the first demonstration of the effect of adipose microenvironment on OC tumor sialylation. Our results set the stage for translational applications targeting sialic acid pathways in OC and other peritoneal cancers.

Combining EHMT and PARP Inhibition: A Strategy to Diminish Therapy-Resistant Ovarian Cancer Tumor Growth while Stimulating Immune Activation

Despite the success of Poly-ADP-ribose polymerase inhibitors (PARPi) in the clinic, high rates of resistance to PARPi presents a challenge in the treatment of ovarian cancer, thus it is imperative to find therapeutic strategies to combat PARPi resistance. Here, we demonstrate that inhibition of epigenetic modifiers Euchromatic histone lysine methyltransferases 1/2 (EHMT1/2) reduces the growth of multiple PARPi-resistant ovarian cancer cell lines and tumor growth in a PARPi-resistant mouse model of ovarian cancer. We found that combinatory EHMT and PARP inhibition increases immunostimulatory dsRNA formation and elicits several immune signaling pathways in vitro. Using epigenomic profiling and transcriptomics, we found that EHMT2 is bound to transposable elements, and that EHMT inhibition leads to genome-wide epigenetic and transcriptional derepression of transposable elements. We validated EHMT-mediated activation of immune signaling and upregulation of transposable element transcripts in patient-derived, therapy-naïve, primary ovarian tumors, suggesting potential efficacy in PARPi-sensitive disease as well. Importantly, using multispectral immunohistochemistry, we discovered that combinatory therapy increased CD8 T cell activity in the tumor microenvironment of the same patient-derived tissues. In a PARPi-resistant syngeneic murine model, EHMT and PARP inhibition combination inhibited tumor progression and increased Granzyme B+ cells in the tumor. Together, our results provide evidence that combinatory EHMT and PARP inhibition stimulates a cell autologous immune response in vitro, is an effective therapy to reduce PARPi resistant ovarian tumor growth in vivo, and promotes anti-tumor immunity activity in the tumor microenvironment of patient-derived ex vivo tissues of ovarian cancer.

ROR2/Wnt5a Signaling Regulates Directional Cell Migration and Early Tumor Cell Invasion in Ovarian Cancer

Adhesion to and clearance of the mesothelial monolayer are key early events in metastatic seeding of ovarian cancer. ROR2 is a receptor tyrosine kinase that interacts with Wnt5a ligand to activate noncanonical Wnt signaling and has been previously shown to be upregulated in ovarian cancer tissue. However, no prior study has evaluated the mechanistic role of ROR2 in ovarian cancer. Through a cellular high-throughput genetic screen, we independently identified ROR2 as a driver of ovarian tumor cell adhesion and invasion. ROR2 expression in ovarian tumor cells serves to drive directed cell migration preferentially toward areas of high Wnt5a ligand, such as the mesothelial lined omentum. In addition, ROR2 promotes ovarian tumor cell adhesion and clearance of a mesothelial monolayer. Depletion of ROR2, in tumor cells, reduces metastatic tumor burden in a syngeneic model of ovarian cancer. These findings support the role of ROR2 in ovarian tumor cells as a critical factor contributing to the early steps of metastasis. Therapeutic targeting of the ROR2/Wnt5a signaling axis could provide a means of improving treatment for patients with advanced ovarian cancer.

IMPLICATIONS

This study demonstrates that ROR2 in ovarian cancer cells is important for directed migration to the metastatic niche and provides a potential signaling axis of interest for therapeutic targeting in ovarian cancer.

Potential role of p53 deregulation in modulating immune responses in human malignancies: A paradigm to develop immunotherapy

The crucial role played by the oncogenic expression of TP53, stemming from mutation or amyloid formation, in various human malignancies has been extensively studied over the past two decades. Interestingly, the potential role of TP53 as a crucial player in modulating immune responses has provided new insight into the field of cancer biology. The loss of p53's transcriptional functions and/or the acquisition of tumorigenic properties can efficiently modulate the recruitment and functions of myeloid and lymphoid cells, ultimately leading to the evasion of immune responses in human tumors. Consequently, the oncogenic nature of the tumor suppressor p53 can dynamically alter the function of immune cells, providing support for tumor progression and metastasis. This review comprehensively explores the dual role of p53 as both the guardian of the genome and an oncogenic driver, especially in the context of regulation of autophagy, apoptosis, the tumor microenvironment, immune cells, innate immunity, and adaptive immune responses. Additionally, the focus of this review centers on how p53 status in the immune response can be harnessed for the development of tailored therapeutic strategies and their potential application in immunotherapy against human malignancies.

Targeting Tryptophan Catabolism in Ovarian Cancer to Attenuate Macrophage Infiltration and PD-L1 Expression

High-grade serous carcinoma (HGSC) of the fallopian tube, ovary, and peritoneum is the most common type of ovarian cancer and is predicted to be immunogenic because the presence of tumor-infiltrating lymphocytes conveys a better prognosis. However, the efficacy of immunotherapies has been limited because of the immune-suppressed tumor microenvironment (TME). Tumor metabolism and immune-suppressive metabolites directly affect immune cell function through the depletion of nutrients and activation of immune-suppressive transcriptional programs. Tryptophan (TRP) catabolism is a contributor to HGSC disease progression. Two structurally distinct rate-limiting TRP catabolizing enzymes, indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan 2,3-dioxygenase 2 (TDO2), evolved separately to catabolize TRP. IDO1/TDO2 are aberrantly expressed in carcinomas and metabolize TRP into the immune-suppressive metabolite kynurenine (KYN), which can engage the aryl hydrocarbon receptor to drive immunosuppressive transcriptional programs. To date, IDO inhibitors tested in clinical trials have had limited efficacy, but those inhibitors did not target TDO2, and we find that HGSC cell lines and clinical outcomes are more dependent on TDO2 than IDO1. To identify inflammatory HGSC cancers with poor prognosis, we stratified patient ascites samples by IL6 status, which correlates with poor prognosis. Metabolomics revealed that IL6-high patient samples had enriched KYN. TDO2 knockdown significantly inhibited HGSC growth and TRP catabolism. The orally available dual IDO1/TDO2 inhibitor, AT-0174, significantly inhibited tumor progression, reduced tumor-associated macrophages, and reduced expression of immune-suppressive proteins on immune and tumor cells. These studies demonstrate the importance of TDO2 and the therapeutic potential of AT-0174 to overcome an immune-suppressed TME.

SIGNIFICANCE

Developing strategies to improve response to chemotherapy is essential to extending disease-free intervals for patients with HGSC of the fallopian tube, ovary, and peritoneum. In this article, we demonstrate that targeting TRP catabolism, particularly with dual inhibition of TDO2 and IDO1, attenuates the immune-suppressive microenvironment and, when combined with chemotherapy, extends survival compared with chemotherapy alone.

Different Patterns of Platinum Resistance in Ovarian Cancer Cells with Homologous Recombination Proficient and Deficient Background

Platinum compounds are very active in first-line treatments of ovarian carcinoma. In fact, high rates of complete remission are achieved, but most patients eventually relapse with resistant disease. Many mechanisms underlying the platinum-resistant phenotype have been reported. However, there are no data in the same isogenic cell system proficient and deficient in homologous recombination (HR) on platinum-acquired resistance that might unequivocally clarify the most important mechanism associated with resistance. We generated and characterized cisplatin (DDP)-resistant murine ovarian ID8 cell lines in a HR-deficient and -proficient background. Specific upregulation of the NER pathway in the HR-proficient and -resistant cells and partial restoration of HR in Brca1-/--resistant cells were found. Combinations of different inhibitors of the DNA damage response pathways with cisplatin were strongly active in both resistant and parental cells. The data from the ID8 isogenic system are in line with current experimental and clinical evidence and strongly suggest that platinum resistance develops in different ways depending on the cell DNA repair status (i.e., HR-proficient or HR-deficient), and the upregulation and/or restoration of repair pathways are major determinants of DDP resistance.

Comprehensive review of CRISPR-based gene editing: mechanisms, challenges, and applications in cancer therapy

The CRISPR system is a revolutionary genome editing tool that has the potential to revolutionize the field of cancer research and therapy. The ability to precisely target and edit specific genetic mutations that drive the growth and spread of tumors has opened up new possibilities for the development of more effective and personalized cancer treatments. In this review, we will discuss the different CRISPR-based strategies that have been proposed for cancer therapy, including inactivating genes that drive tumor growth, enhancing the immune response to cancer cells, repairing genetic mutations that cause cancer, and delivering cancer-killing molecules directly to tumor cells. We will also summarize the current state of preclinical studies and clinical trials of CRISPR-based cancer therapy, highlighting the most promising results and the challenges that still need to be overcome. Safety and delivery are also important challenges for CRISPR-based cancer therapy to become a viable clinical option. We will discuss the challenges and limitations that need to be overcome, such as off-target effects, safety, and delivery to the tumor site. Finally, we will provide an overview of the current challenges and opportunities in the field of CRISPR-based cancer therapy and discuss future directions for research and development. The CRISPR system has the potential to change the landscape of cancer research, and this review aims to provide an overview of the current state of the field and the challenges that need to be overcome to realize this potential.

FGL2 promotes tumour growth and attenuates infiltration of activated immune cells in melanoma and ovarian cancer models

The tumour microenvironment is infiltrated by immunosuppressive cells, such as regulatory T cells (Tregs), which contribute to tumour escape and impede immunotherapy outcomes. Soluble fibrinogen-like protein 2 (sFGL2), a Treg effector protein, inhibits immune cell populations, via receptors FcγRIIB and FcγRIII, leading to downregulation of CD86 in antigen presenting cells and limiting T cell activation. Increased FGL2 expression is associated with tumour progression and poor survival in several different cancers, such as glioblastoma multiforme, lung, renal, liver, colorectal, and prostate cancer. Querying scRNA-seq human cancer data shows FGL2 is produced by cells in the tumour microenvironment (TME), particularly monocytes and macrophages as well as T cells and dendritic cells (DCs), while cancer cells have minimal expression of FGL2. We studied the role of FGL2 exclusively produced by cells in the TME, by leveraging Fgl2 knockout mice. We tested two murine models of cancer in which the role of FGL2 has not been previously studied: epithelial ovarian cancer and melanoma. We show that absence of FGL2 leads to a more activated TME, including activated DCs (CD86+, CD40+) and T cells (CD25+, TIGIT+), as well as demonstrating for the first time that the absence of FGL2 leads to more activated natural killer cells (DNAM-1+, NKG2D+) in the TME. Furthermore, the absence of FGL2 leads to prolonged survival in the B16F10 melanoma model, while the absence of FGL2 synergizes with oncolytic virus to prolong survival in the ID8-p53-/-Brca2-/- ovarian cancer model. In conclusion, targeting FGL2 is a promising cancer treatment strategy alone and in combination immunotherapies.

NLRC5 overexpression in ovarian tumors remodels the tumor microenvironment and increases T-cell reactivity toward autologous tumor-associated antigens

Introduction

Epithelial ovarian cancer (OC) stands as one of the deadliest gynecologic malignancies, urgently necessitating novel therapeutic strategies. Approximately 60% of ovarian tumors exhibit reduced expression of major histocompatibility complex class I (MHC I), intensifying immune evasion mechanisms and rendering immunotherapies ineffective. NOD-like receptor CARD domain containing 5 (NLRC5) transcriptionally regulates MHC I genes and many antigen presentation machinery components. We therefore explored the therapeutic potential of NLRC5 in OC.

Methods

We generated OC cells overexpressing NLRC5 to rescue MHC I expression and antigen presentation and then assessed their capability to respond to PD-L1 blockade and an infected cell vaccine.

Results

Analysis of microarray datasets revealed a correlation between elevated NLRC5 expression and extended survival in OC patients; however, NLRC5 was scarcely detected in the OC tumor microenvironment. OC cells overexpressing NLRC5 exhibited slower tumor growth and resulted in higher recruitment of leukocytes in the TME with lower CD4/CD8 T-cell ratios and increased activation of T cells. Immune cells from peripheral blood, spleen, and ascites from these mice displayed heightened activation and interferon-gamma production when exposed to autologous tumor-associated antigens. Finally, as a proof of concept, NLRC5 overexpression within an infected cell vaccine platform enhanced responses and prolonged survival in comparison with control groups when challenged with parental tumors.

Discussion

These findings provide a compelling rationale for utilizing NLRC5 overexpression in "cold" tumor models to enhance tumor susceptibility to T-cell recognition and elimination by boosting the presentation of endogenous tumor antigens. This approach holds promise for improving antitumoral immune responses in OC.

Biology-driven therapy advances in high-grade serous ovarian cancer

Following a period of slow progress, the completion of genome sequencing and the paradigm shift relative to the cell of origin for high grade serous ovarian cancer (HGSOC) led to a new perspective on the biology and therapeutic solutions for this deadly cancer. Experimental models were revisited to address old questions, and improved tools were generated. Additional pathways emerging as drivers of ovarian tumorigenesis and key dependencies for therapeutic targeting, in particular, VEGF-driven angiogenesis and homologous recombination deficiency, were discovered. Molecular profiling of histological subtypes of ovarian cancer defined distinct genetic events for each entity, enabling the first attempts toward personalized treatment. Armed with this knowledge, HGSOC treatment was revised to include new agents. Among them, PARP inhibitors (PARPis) were shown to induce unprecedented improvement in clinical benefit for selected subsets of patients. Research on mechanisms of resistance to PARPis is beginning to discover vulnerabilities and point to new treatment possibilities. This Review highlights these advances, the remaining challenges, and unsolved problems in the field.

OT-I TCR Transgenic Mice to Study the Role of PTPN22 in Anti-cancer Immunity

Phosphotyrosine phosphatase non-receptor type 22 (PTPN22) is a key regulator of immune cell activation and responses. Genetic polymorphisms of PTPN22 have been strongly linked with an increased risk of developing autoimmune diseases, while analysis of PTPN22-deficient mouse strains has determined that PTPN22 serves as a negative regulator of T cell antigen receptor signaling. As well as these key roles in maintaining immune tolerance, PTPN22 acts as an intracellular checkpoint for T cell responses to cancer, suggesting that PTPN22 might be a useful target to improve T cell immunotherapies. To assess the potential for targeting PTPN22, we have crossed Ptpn22-deficient mice to an OT-I TCR transgenic background and used adoptive T cell transfer approaches in mouse cancer models. We provide basic methods for the in vitro expansion of effector OT-I cytotoxic T lymphocytes, in vitro phenotypic analysis, and in vivo adoptive T cell transfer models to assess the role of PTPN22 in anti-cancer immunity.

DDR2-regulated arginase activity in ovarian cancer-associated fibroblasts promotes collagen production and tumor progression

Ovarian cancer has poor survival outcomes particularly for advanced stage, metastatic disease. Metastasis is promoted by interactions of stromal cells, such as cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME), with tumor cells. CAFs play a key role in tumor progression by remodeling the TME and extracellular matrix (ECM) to result in a more permissive environment for tumor progression. It has been shown that fibroblasts, in particular myofibroblasts, utilize metabolism to support ECM remodeling. However, the intricate mechanisms by which CAFs support collagen production and tumor progression are poorly understood. In this study, we show that the fibrillar collagen receptor, Discoidin Domain Receptor 2 (DDR2), promotes collagen production in human and mouse omental CAFs through arginase activity. CAFs with high DDR2 or arginase promote tumor colonization in the omentum. In addition, DDR2-depleted CAFs had decreased ornithine levels leading to decreased collagen production and polyamine levels compared to WT control CAFs. Tumor cell invasion was decreased in the presence CAF conditioned media (CM) depleted of DDR2 or arginase-1, and this invasion defect was rescued in the presence of CM from DDR2-depleted CAFs that constitutively overexpressed arginase-1. Similarly, the addition of exogenous polyamines to CM from DDR2-depleted CAFs led to increased tumor cell invasion. We detected SNAI1 protein at the promoter region of the arginase-1 gene, and DDR2-depleted CAFs had decreased levels of SNAI1 protein at the arginase-1 promoter region. Furthermore, high stromal arginase-1 expression correlated with poor survival in ovarian cancer patients. These findings highlight how DDR2 regulates collagen production by CAFs in the tumor microenvironment by controlling the transcription of arginase-1, and CAFs are a major source of arginase activity and L-arginine metabolites in ovarian cancer models.

Nrf2, A Target for Precision Oncology in Cancer Prognosis and Treatment

Activating nuclear factor-erythroid 2-related factor (Nrf2), a master regulator of redox homeostasis, has been shown to suppress initiation of carcinogenesis in normal cells. However, this transcription factor has recently been reported to promote proliferation of some transformed or cancerous cells. In tumor cells, Nrf2 is prone to mutations that result in stabilization and concurrent accumulation of its protein product. A hyperactivated mutant form of Nrf2 could support the cancer cells for enhanced proliferation, invasiveness, and resistance to chemotherapeutic agents and radiotherapy, which are associated with a poor clinical outcome. Hence understanding mutations in Nrf2 would have a significant impact on the prognosis and treatment of cancer in the era of precision medicine. This perspective would provide an insight into the genetic alterations in Nrf2 and suggest the application of small molecules, RNAi, and genome editing technologies, particularly CRISR-Cas9, in therapeutic intervention of cancer in the context of the involvement of Nrf2 mutations.

miR-146a inhibits ovarian tumor growth in vivo via targeting immunosuppressive neutrophils and enhancing CD8+ T cell infiltration

Immunotherapies have emerged as promising strategies for cancer treatment. However, existing immunotherapies have poor activity in high-grade serous ovarian cancer (HGSC) due to the immunosuppressive tumor microenvironment and the associated low tumoral CD8+ T cell (CTL) infiltration. Through multiple lines of evidence, including integrative analyses of human HGSC tumors, we have identified miR-146a as a master regulator of CTL infiltration in HGSC. Tumoral miR-146a expression is positively correlated with anti-cancer immune signatures in human HGSC tumors, and delivery of miR-146a to tumors resulted in significant reduction in tumor growth in both ID8-p53-/- and IG10 murine HGSC models. Increasing miR-146a expression in tumors improved anti-tumor immune responses by decreasing immune suppressive neutrophils and increasing CTL infiltration. Mechanistically, miR-146a targets IL-1 receptor-associated kinase 1 and tumor necrosis factor receptor-associated factor 6 adaptor molecules of the transcription factor nuclear factor κB signaling pathway in ID8-p53-/- cells and decreases production of the downstream neutrophil chemoattractant, C-X-C motif chemokine ligand 1. In addition to HGSC, tumoral miR-146a expression also correlates strongly with CTL infiltration in other cancer types including thyroid, prostate, breast, and adrenocortical cancers. Altogether, our findings highlight the ability of miR-146a to overcome immune suppression and improve CTL infiltration in tumors.

Deletion of the protein tyrosine phosphatase PTPN22 for adoptive T cell therapy facilitates CTL effector function but promotes T cell exhaustion

BACKGROUND

Adoptive cell therapy (ACT) is a promising strategy for treating cancer, yet it faces several challenges such as lack of long-term protection due to T cell exhaustion induced by chronic TCR stimulation in the tumor microenvironment. One benefit of ACT, however, is that it allows for cellular manipulations, such as deletion of the phosphotyrosine phosphatase non-receptor type 22 (PTPN22), which improves CD8+ T cell antitumor efficacy in ACT. We tested whether Ptpn22KO cytolytic T cells (CTLs) were also more effective than Ptpn22WT CTL in controlling tumors in scenarios that favor T cell exhaustion.

METHODS

Tumor control by Ptpn22WT and Ptpn22KO CTL was assessed following adoptive transfer of low numbers of CTL to mice with subcutaneously implanted MC38 tumors. Tumor infiltrating lymphocytes were isolated for analysis of effector functions. An in vitro assay was established to compare CTL function in response to acute and chronic restimulation with antigen-pulsed tumor cells. The expression of effector and exhaustion-associated proteins by Ptpn22WT and Ptpn22KO T cells was followed over time in vitro and in vivo using the ID8 tumor model. Finally, the effect of PD-1 and TIM-3 blockade on Ptpn22KO CTL tumor control was assessed using monoclonal antibodies and CRISPR/Cas9-mediated knockout.

RESULTS

Despite having improved effector function at the time of transfer, Ptpn22KO CTL became more exhausted than Ptpn22WT CTL, characterized by more rapid loss of effector functions, and earlier and higher expression of inhibitory receptors (IRs), particularly the terminal exhaustion marker TIM-3. TIM-3 expression, under the control of the transcription factor NFIL3, was induced by IL-2 signaling which was enhanced in Ptpn22KO cells. Antitumor responses of Ptpn22KO CTL were improved following PD-1 blockade in vivo, yet knockout or antibody-mediated blockade of TIM-3 did not improve but further impaired tumor control, indicating TIM-3 signaling itself did not drive the diminished function seen in Ptpn22KO CTL.

CONCLUSIONS

This study questions whether TIM-3 plays a role as an IR and highlights that genetic manipulation of T cells for ACT needs to balance short-term augmented effector function against the risk of T cell exhaustion in order to achieve longer-term protection.

BRCA1 and BRCA2 deficient tumour models generate distinct ovarian tumour microenvironments and differential responses to therapy

Clinical trials are currently exploring combinations of PARP inhibitors and immunotherapies for the treatment of ovarian cancer, but their effects on the ovarian tumour microenvironment (TME) remain unclear. Here, we investigate how olaparib, PD-L1 monoclonal antibodies, and their combination can influence TME composition and survival of tumour-bearing mice. We further explored how BRCA deficiencies can influence the response to therapy. Olaparib and combination therapies similarly improved the median survival of Brca1- and Brca2-deficient tumour-bearing mice. Anti-PD-L1 monotherapy improved the survival of mice with Brca1-null tumours, but not Brca2-null tumours. A detailed analysis of the TME revealed that olaparib monotherapy resulted in a large number of immunosuppressive and immunomodulatory effects in the more inflamed Brca1-deficient TME but not Brca2-deficient tumours. Anti-PD-L1 treatment was mostly immunosuppressive, resulting in a systemic reduction of cytokines and a compensatory increase in PD-L1 expression. The results of the combination therapy generally resembled the effects of one or both of the monotherapies, along with unique changes observed in certain immune populations. In-silico analysis of RNA-seq data also revealed numerous differences between Brca-deficient tumour models, such as the expression of genes involved in inflammation, angiogenesis and PD-L1 expression. In summary, these findings shed light on the influence of novel therapeutics and BRCA mutations on the ovarian TME.

Comparative analysis of syngeneic mouse models of high-grade serous ovarian cancer

Ovarian cancers exhibit high rates of recurrence and poor treatment response. Preclinical models that recapitulate human disease are critical to develop new therapeutic approaches. Syngeneic mouse models allow for the generation of tumours comprising the full repertoire of non-malignant cell types but have expanded in number, varying in the cell type of origin, method for transformation, and ultimately, the properties of the tumours they produce. Here we have performed a comparative analysis of high-grade serous ovarian cancer models based on transcriptomic profiling of 22 cell line models, and intrabursal and intraperitoneal tumours from 12. Among cell lines, we identify distinct signalling activity, such as elevated inflammatory signalling in STOSE and OVE16 models, and MAPK/ERK signalling in ID8 and OVE4 models; metabolic differences, such as reduced glycolysis-associated expression in several engineered ID8 subclones; and relevant functional properties, including differences in EMT activation, PD-L1 and MHC class I expression, and predicted chemosensitivity. Among tumour samples, we observe increased variability and stromal content among intrabursal tumours. Finally, we predict differences in the microenvironment of ID8 models engineered with clinically relevant mutations. We anticipate that this work will serve as a valuable resource, providing new insight to help select models for specific experimental objectives.

Tumor-derived systems as novel biomedical tools-turning the enemy into an ally

Cancer is a complex illness that presents significant challenges in its understanding and treatment. The classic definition, "a group of diseases characterized by the uncontrolled growth and spread of abnormal cells in the body," fails to convey the intricate interaction between the many entities involved in cancer. Recent advancements in the field of cancer research have shed light on the role played by individual cancer cells and the tumor microenvironment as a whole in tumor development and progression. This breakthrough enables the utilization of the tumor and its components as biological tools, opening new possibilities. This article delves deeply into the concept of "tumor-derived systems", an umbrella term for tools sourced from the tumor that aid in combatting it. It includes cancer cell membrane-coated nanoparticles (for tumor theranostics), extracellular vesicles (for tumor diagnosis/therapy), tumor cell lysates (for cancer vaccine development), and engineered cancer cells/organoids (for cancer research). This review seeks to offer a complete overview of the tumor-derived materials that are utilized in cancer research, as well as their current stages of development and implementation. It is aimed primarily at researchers working at the interface of cancer biology and biomedical engineering, and it provides vital insights into this fast-growing topic.

Pevonedistat, a first-in-class NEDD8-activating enzyme inhibitor, sensitizes cancer cells to VSVΔ51 oncolytic virotherapy

The clinical efficacy of VSVΔ51 oncolytic virotherapy has been limited by tumor resistance to viral infection, so strategies to transiently repress antiviral defenses are warranted. Pevonedistat is a first-in-class NEDD8-activating enzyme (NAE) inhibitor currently being tested in clinical trials for its antitumor potential. In this study, we demonstrate that pevonedistat sensitizes human and murine cancer cells to increase oncolytic VSVΔ51 infection, increase tumor cell death, and improve therapeutic outcomes in resistant syngeneic murine cancer models. Increased VSVΔ51 infectivity was also observed in clinical human tumor samples. We further identify the mechanism of this effect to operate via blockade of the type 1 interferon (IFN-1) response through neddylation-dependent interferon-stimulated growth factor 3 (ISGF3) repression and neddylation-independent inhibition of NF-κB nuclear translocation. Together, our results identify a role for neddylation in regulating the innate immune response and demonstrate that pevonedistat can improve the therapeutic outcomes of strategies using oncolytic virotherapy.

Stromal DDR2 Promotes Ovarian Cancer Metastasis through Regulation of Metabolism and Secretion of Extracellular Matrix Proteins

Ovarian cancer is the leading cause of gynecologic cancer-related deaths. The propensity for metastasis within the peritoneal cavity is a driving factor for the poor outcomes associated with this disease, but there is currently no effective therapy targeting metastasis. In this study, we investigate the contribution of stromal cells to ovarian cancer metastasis and identify normal stromal cell expression of the collagen receptor, discoidin domain receptor 2 (DDR2), that acts to facilitate ovarian cancer metastasis. In vivo, global genetic inactivation of Ddr2 impairs the ability of Ddr2-expressing syngeneic ovarian cancer cells to spread throughout the peritoneal cavity. Specifically, DDR2 expression in mesothelial cells lining the peritoneal cavity facilitates tumor cell attachment and clearance. Subsequently, omentum fibroblast expression of DDR2 promotes tumor cell invasion. Mechanistically, we find DDR2-expressing fibroblasts are more energetically active, such that DDR2 regulates glycolysis through AKT/SNAI1 leading to suppressed fructose-1,6-bisphosphatase and increased hexokinase activity, a key glycolytic enzyme. Upon inhibition of DDR2, we find decreased protein synthesis and secretion. Consequently, when DDR2 is inhibited, there is reduction in secreted extracellular matrix proteins important for metastasis. Specifically, we find that fibroblast DDR2 inhibition leads to decreased secretion of the collagen crosslinker, LOXL2. Adding back LOXL2 to DDR2 deficient fibroblasts rescues the ability of tumor cells to invade. Overall, our results suggest that stromal cell expression of DDR2 is an important mediator of ovarian cancer metastasis.

IMPLICATIONS

DDR2 is highly expressed by stromal cells in ovarian cancer that can mediate metastasis and is a potential therapeutic target in ovarian cancer.

Pharmacological depletion of RNA splicing factor RBM39 by indisulam synergizes with PARP inhibitors in high-grade serous ovarian carcinoma

Ovarian high-grade serous carcinoma (HGSC) is the most common subtype of ovarian cancer with limited therapeutic options and a poor prognosis. In recent years, poly-ADP ribose polymerase (PARP) inhibitors have demonstrated significant clinical benefits, especially in patients with BRCA1/2 mutations. However, acquired drug resistance and relapse is a major challenge. Indisulam (E7070) has been identified as a molecular glue that brings together splicing factor RBM39 and DCAF15 E3 ubiquitin ligase resulting in polyubiquitination, degradation, and subsequent RNA splicing defects. In this work, we demonstrate that the loss of RBM39 induces splicing defects in key DNA damage repair genes in ovarian cancer, leading to increased sensitivity to cisplatin and various PARP inhibitors. The addition of indisulam also improved olaparib response in mice bearing PARP inhibitor-resistant tumors. These findings demonstrate that combining RBM39 degraders and PARP inhibitors is a promising therapeutic approach to improve PARP inhibitor response in ovarian HGSC.

Intermittent fasting induced ketogenesis inhibits mouse epithelial ovarian cancer by promoting antitumor T cell response

In various cancer models, dietary interventions have been shown to inhibit tumor growth, improve anticancer drug efficacy, and enhance immunity, but no such evidence exists for epithelial ovarian cancer (EOC), the most lethal gynecologic cancer. The anticancer immune responses induced by 16-h intermittent fasting (IF) were studied in mice with EOC. IF consistently reduced metabolic growth factors and cytokines that stimulate tumor growth, creating a tumor-hostile environment. Immune profiling showed that IF dramatically alters anti-cancer immunity by increasing CD4+ and CD8+ cells, Th1 and cytotoxic responses, and metabolic fitness. β-hydroxy butyrate (BHB), a bioactive metabolite produced by IF, partially imitates its anticancer effects by inducing CD8+ effector function. In a direct comparison, IF outperformed exogenous BHB treatment in survival and anti-tumor immune response, probably due to increased ketogenesis. Thus, IF and one of its metabolic mediators BHB suppress EOC growth and sustain a potent anti-tumor T cell response.

PTEN deficiency exposes a requirement for an ARF GTPase module for integrin-dependent invasion in ovarian cancer

Dysregulation of the PI3K/AKT pathway is a common occurrence in high-grade serous ovarian carcinoma (HGSOC), with the loss of the tumour suppressor PTEN in HGSOC being associated with poor prognosis. The cellular mechanisms of how PTEN loss contributes to HGSOC are largely unknown. We here utilise time-lapse imaging of HGSOC spheroids coupled to a machine learning approach to classify the phenotype of PTEN loss. PTEN deficiency induces PI(3,4,5)P3 -rich and -dependent membrane protrusions into the extracellular matrix (ECM), resulting in a collective invasion phenotype. We identify the small GTPase ARF6 as a crucial vulnerability of HGSOC cells upon PTEN loss. Through a functional proteomic CRISPR screen of ARF6 interactors, we identify the ARF GTPase-activating protein (GAP) AGAP1 and the ECM receptor β1-integrin (ITGB1) as key ARF6 interactors in HGSOC regulating PTEN loss-associated invasion. ARF6 functions to promote invasion by controlling the recycling of internalised, active β1-integrin to maintain invasive activity into the ECM. The expression of the CYTH2-ARF6-AGAP1 complex in HGSOC patients is inversely associated with outcome, allowing the identification of patient groups with improved versus poor outcome. ARF6 may represent a therapeutic vulnerability in PTEN-depleted HGSOC.

PG545 sensitizes ovarian cancer cells to PARP inhibitors through modulation of RAD51-DEK interaction

PG545 (Pixatimod) is a highly sulfated small molecule known for its ability to inhibit heparanase and disrupt signaling mediated by heparan-binding-growth factors (HB-GF). Previous studies indicated that PG545 inhibits growth factor-mediated signaling in ovarian cancer (OC) to enhance response to chemotherapy. Here we investigated the previously unidentified mechanisms by which PG545 induces DNA damage in OC cells and found that PG545 induces DNA single- and double-strand breaks, reduces RAD51 expression in an autophagy-dependent manner and inhibits homologous recombination repair (HRR). These changes accompanied the ability of PG545 to inhibit endocytosis of the heparan-sulfate proteoglycan interacting DNA repair protein, DEK, leading to DEK sequestration in the tumor microenvironment (TME) and loss of nuclear DEK needed for HRR. As a result, PG545 synergized with poly (ADP-ribose) polymerase inhibitors (PARPis) in OC cell lines in vitro and in 55% of primary cultures of patient-derived ascites samples ex vivo. Moreover, PG545/PARPi synergy was observed in OC cells exhibiting either de novo or acquired resistance to PARPi monotherapy. PG545 in combination with rucaparib also generated increased DNA damage, increased antitumor effects and increased survival of mice bearing HRR proficient OVCAR5 xenografts compared to monotherapy treatment in vivo. Synergistic antitumor activity of the PG545/rucaparib combination was likewise observed in an immunocompetent syngeneic ID8F3 OC model. Collectively, these results suggest that targeting DEK-HSPG interactions in the TME through the use of PG545 may be a novel method of inhibiting DNA repair and sensitizing cells to PARPis.

The role of p53 in anti-tumor immunity and response to immunotherapy

p53 is a transcription factor that regulates the expression of genes involved in tumor suppression. p53 mutations mediate tumorigenesis and occur in approximately 50% of human cancers. p53 regulates hundreds of target genes that induce various cell fates including apoptosis, cell cycle arrest, and DNA damage repair. p53 also plays an important role in anti-tumor immunity by regulating TRAIL, DR5, TLRs, Fas, PKR, ULBP1/2, and CCL2; T-cell inhibitory ligand PD-L1; pro-inflammatory cytokines; immune cell activation state; and antigen presentation. Genetic alteration of p53 can contribute to immune evasion by influencing immune cell recruitment to the tumor, cytokine secretion in the TME, and inflammatory signaling pathways. In some contexts, p53 mutations increase neoantigen load which improves response to immune checkpoint inhibition. Therapeutic restoration of mutated p53 can restore anti-cancer immune cell infiltration and ameliorate pro-tumor signaling to induce tumor regression. Indeed, there is clinical evidence to suggest that restoring p53 can induce an anti-cancer immune response in immunologically cold tumors. Clinical trials investigating the combination of p53-restoring compounds or p53-based vaccines with immunotherapy have demonstrated anti-tumor immune activation and tumor regression with heterogeneity across cancer type. In this Review, we discuss the impact of wild-type and mutant p53 on the anti-tumor immune response, outline clinical progress as far as activating p53 to induce an immune response across a variety of cancer types, and highlight open questions limiting effective clinical translation.