BET, SRC, and BCL2 family inhibitors are synergistic drug combinations with PARP inhibitors in ovarian cancer

Overview of BH3 mimetics in ovarian cancer

Ovarian carcinoma is the leading cause of gynecological cancer-related death, still with a dismal five-year prognosis, mainly due to late diagnosis and the emergence of resistance to cytotoxic and targeted agents. Bcl-2 family proteins have a key role in apoptosis and are associated with tumor development/progression and response to therapy in different cancer types, including ovarian carcinoma. In tumors, evasion of apoptosis is a possible mechanism of resistance to therapy. BH3 mimetics are small molecules that occupy the hydrophobic pocket on pro-survival proteins, allowing the induction of apoptosis, and are currently under study as single agents and/or in combination with cytotoxic and targeted agents in solid tumors. Here, we discuss recent advances in targeting anti-apoptotic proteins of the Bcl-2 family for the treatment of ovarian cancer, focusing on BH3 mimetics, and how these approaches could potentially offer an alternative/complementary way to treat patients and overcome or delay resistance to current treatments.

Antineoplastic Drug Synergy of Artesunate with Navitoclax in Models of High-Grade Serous Ovarian Cancer

Artesunate belongs to a class of medications derived from the sweet wormwood plant (Artemisia annua) known as artemisinins. Artesunate has traditionally been used as a frontline treatment for severe malaria but has also demonstrated antineoplastic activity against various malignancies, including ovarian cancer. Data suggest that artesunate exacerbates cellular oxidative stress, triggering apoptosis. In the current study, we investigated the ability of navitoclax, an inhibitor of the antiapoptotic Bcl-2 protein family, to enhance artesunate efficacy in ovarian cancer cells. Artesunate and navitoclax both demonstrated antiproliferative effects on 2D and 3D ovarian cancer cell models as single agents. Upon combination of navitoclax with artesunate, antineoplastic drug synergy was also observed in each of the 2D cell lines and ovarian tumor organoid models tested. Further investigation of this drug combination using intraperitoneal CAOV3 xenograft models in BALB/scid mice showed that the artesunate/navitoclax doublet was superior to single-agent artesunate and vehicle control treatment. However, it did not outperform single-agent navitoclax. With optimization, this drug combination could provide a new therapeutic option for ovarian cancer and warrants further preclinical investigation.

BET bromodomain inhibitors PFI-1 and CPI-203 suppress the development of follicular lymphoma via regulating Wnt/β-catenin signaling

Objective

Follicular lymphoma (FL) is an indolent B-cell lymphoproliferative disorder, characterized by a lymphoid follicular pattern of growth. PFI-1 or CPI-203 has been known to effectively promote the inhibition of primary effusion lymphoma progression. This study aimed at investigating the anti-tumor properties of PFI-1 and CPI-203 on FL cells and uncover the underlying mechanism of action.

Methods

FL cells were treated with PFI-1 and CPI-203, and the treated cells were evaluated for their cell viability, cell cycle and apoptosis using CCK8, flow cytometry, and Western blot assays. A xenograft mouse model was used for assessing the in vivo effects of CPI-203 on tumorigenesis.

Results

PFI-1 or CPI-203 showed potential inhibitory effects on the cell viability of DOHH2 and RL cells in a dose-response-dependent manner. Furthermore, PFI-1 and CPI-203 inhibited cell growth, induced apoptosis of FL cells in vitro, and facilitated the translocation of β-catenin into cytoplasm both in vitro and in vivo. After engrafted with FL cells, CPI-203-treated mice got a longer duration of survival and a smaller tumor size than control mice. Mechanistically, PFI-1 and CPI-203 impede the activity of β-catenin and its downstream molecules by regulating the DVL2/GSK3β axis.

Conclusion

In conclusion, PFI-1 and CPI-203 may serve as potential anti-tumor inhibitors for the therapy of FL.

Using graph-based model to identify cell specific synthetic lethal effects

Synthetic lethal (SL) pairs are pairs of genes whose simultaneous loss-of-function results in cell death, while a damaging mutation of either gene alone does not affect the cell's survival. This makes SL pairs attractive targets for precision cancer therapies, as targeting the unimpaired gene of the SL pair can selectively kill cancer cells that already harbor the impaired gene. Limited by the difficulty of finding true SL pairs, especially on specific cell types, current computational approaches provide only limited insights because of overlooking the crucial aspects of cellular context dependency and mechanistic understanding of SL pairs. As a result, the identification of SL targets still relies on expensive, time-consuming experimental approaches. In this work, we applied cell-line specific multi-omics data to a specially designed deep learning model to predict cell-line specific SL pairs. Through incorporating multiple types of cell-specific omics data with a self-attention module, we represent gene relationships as graphs. Our approach achieves the prediction of SL pairs in a cell-specific manner and demonstrates the potential to facilitate the discovery of cell-specific SL targets for cancer therapeutics, providing a tool to unearth mechanisms underlying the origin of SL in cancer biology. The code and data of our approach can be found at https://github.com/promethiume/SLwise.

First-in-human Study of AZD5153, A Small-molecule Inhibitor of Bromodomain Protein 4, in Patients with Relapsed/Refractory Malignant Solid Tumors and Lymphoma

AZD5153, a reversible, bivalent inhibitor of the bromodomain and extraterminal family protein BRD4, has preclinical activity in multiple tumors. This first-in-human, phase I study investigated AZD5153 alone or with olaparib in patients with relapsed/refractory solid tumors or lymphoma. Adults with relapsed tumors intolerant of, or refractory to, prior therapies received escalating doses of oral AZD5153 once daily or twice daily continuously (21-day cycles), or AZD5153 once daily/twice daily continuously or intermittently plus olaparib 300 mg twice daily, until disease progression or unacceptable toxicity. Between June 30, 2017 and April 19, 2021, 34 patients received monotherapy and 15 received combination therapy. Dose-limiting toxicities were thrombocytopenia/platelet count decreased (n = 4/n = 2) and diarrhea (n = 1). The recommended phase II doses (RP2D) were AZD5153 30 mg once daily or 15 mg twice daily (monotherapy) and 10 mg once daily (intermittent schedule) with olaparib. With AZD5153 monotherapy, common treatment-emergent adverse events (TEAE) included fatigue (38.2%), thrombocytopenia, and diarrhea (each 32.4%); common grade ≥ 3 TEAEs were thrombocytopenia (14.7%) and anemia (8.8%). With the combination, common TEAEs included nausea (66.7%) and fatigue (53.3%); the most common grade ≥ 3 TEAE was thrombocytopenia (26.7%). AZD5153 had dose-dependent pharmacokinetics, with minimal accumulation, and demonstrated dose-dependent modulation of peripheral biomarkers, including upregulation of HEXIM1. One patient with metastatic pancreatic cancer receiving combination treatment had a partial response lasting 4.2 months. These results show AZD5153 was tolerable as monotherapy and in combination at the RP2Ds; common toxicities were fatigue, hematologic AEs, and gastrointestinal AEs. Strong evidence of peripheral target engagement was observed.

The dynamic process of covalent and non-covalent PARylation in the maintenance of genome integrity: a focus on PARP inhibitors

Poly(ADP-ribosylation) (PARylation) by poly(ADP-ribose) polymerases (PARPs) is a highly regulated process that consists of the covalent addition of polymers of ADP-ribose (PAR) through post-translational modifications of substrate proteins or non-covalent interactions with PAR via PAR binding domains and motifs, thereby reprogramming their functions. This modification is particularly known for its central role in the maintenance of genomic stability. However, how genomic integrity is controlled by an intricate interplay of covalent PARylation and non-covalent PAR binding remains largely unknown. Of importance, PARylation has caught recent attention for providing a mechanistic basis of synthetic lethality involving PARP inhibitors (PARPi), most notably in homologous recombination (HR)-deficient breast and ovarian tumors. The molecular mechanisms responsible for the anti-cancer effect of PARPi are thought to implicate both catalytic inhibition and trapping of PARP enzymes on DNA. However, the relative contribution of each on tumor-specific cytotoxicity is still unclear. It is paramount to understand these PAR-dependent mechanisms, given that resistance to PARPi is a challenge in the clinic. Deciphering the complex interplay between covalent PARylation and non-covalent PAR binding and defining how PARP trapping and non-trapping events contribute to PARPi anti-tumour activity is essential for developing improved therapeutic strategies. With this perspective, we review the current understanding of PARylation biology in the context of the DNA damage response (DDR) and the mechanisms underlying PARPi activity and resistance.

Bcl-2 family inhibitors sensitize human cancer models to therapy

BH3 mimetics, targeting the Bcl-2 family anti-apoptotic proteins, represent a promising therapeutic opportunity in cancers. ABT-199, the first specific Bcl-2 inhibitor, was approved by FDA for the treatment of several hematological malignancies. We have recently discovered IS21, a novel pan BH3 mimetic with preclinical antitumor activity in several tumor types. Here, we evaluated the efficacy of IS21 and other BH3 mimetics, both as single agents and combined with the currently used antineoplastic agents in T-cell acute lymphoblastic leukemia, ovarian cancer, and melanoma. IS21 was found to be active in T-cell acute lymphoblastic leukemia, melanoma, lung, pancreatic, and ovarian cancer cell lines. Bcl-xL and Mcl-1 protein levels predicted IS21 sensitivity in melanoma and ovarian cancer, respectively. Exploring IS21 mechanism of action, we found that IS21 activity depends on the presence of BAX and BAK proteins: complexes between Bcl-2 and Bcl-xL proteins and their main binding partners were reduced after IS21 treatment. In combination experiments, BH3 mimetics sensitized leukemia cells to chemotherapy, ovarian cancer cells and melanoma models to PARP and MAPK inhibitors, respectively. We showed that this enhancing effect was related to the potentiation of the apoptotic pathway, both in hematologic and solid tumors. In conclusion, our data suggest the use of inhibitors of anti-apoptotic proteins as a therapeutic strategy to enhance the efficacy of anticancer treatment.

Discovery of Ruthenium(II) Metallocompound and Olaparib Synergy for Cancer Combination Therapy

Synergistic drug combinations can extend the use of poly(ADP-ribose) polymerase inhibitors (PARPi) such as Olaparib to BRCA-proficient tumors and overcome acquired or de novo drug resistance. To identify new synergistic combinations for PARPi, we screened a "micro-library" comprising a mix of commercially available drugs and DNA-binding ruthenium(II) polypyridyl complexes (RPCs) for Olaparib synergy in BRCA-proficient triple-negative breast cancer cells. This identified three hits: the natural product Curcumin and two ruthenium(II)-rhenium(I) polypyridyl metallomacrocycles. All combinations identified were effective in BRCA-proficient breast cancer cells, including an Olaparib-resistant cell line, and spheroid models. Mechanistic studies indicated that synergy was achieved via DNA-damage enhancement and resultant apoptosis. Combinations showed low cytotoxicity toward non-malignant breast epithelial cells and low acute and developmental toxicity in zebrafish embryos. This work identifies RPC metallomacrocycles as a novel class of agents for cancer combination therapy and provides a proof of concept for the inclusion of metallocompounds within drug synergy screens.

Experimental drugs for fallopian cancer: promising agents in the clinical trials and key stumbling blocks for researchers

INTRODUCTION

Fallopian tube carcinoma (FC) as a single entity is a rare disease. Although its diagnosis is increasing thanks to the widespread use of prophylactic salpingectomy, there are no clinical trials exclusively designed for FC.

AREAS COVERED

This review aims at identifying the most promising trials and future therapeutic pathways in the setting of FC.

EXPERT OPINION

Hot topics in FC treatment include the consequences of using PARP inhibitors (PARPi) as first-line therapy, ways to overcome platinum resistance, and the role of immunotherapy. Patient selection is a key point for future development of target therapies. Next-generation sequencing (NGS) is one of the most investigated technologies both for drug discovery and identification of reverse mutations, involved in resistance to PARPi and platinum. New, promising molecular targets are emerging. Notwithstanding the disappointing outcomes when used by itself, immunotherapy in FC treatment could still have a role in combination with other agents, exploiting synergistic effects at the molecular level. The development of cancer vaccines is currently hampered by the high variability of tumor neoantigens in FC. Genomic profiling could be a solution, allowing the synthesis of individualized vaccines.

Targeting Homologous Recombination Deficiency in Ovarian Cancer with PARP Inhibitors: Synthetic Lethal Strategies That Impact Overall Survival

Simple Summary

Synthetic lethality approaches to cancer therapy involves combining events to cause cancer cell death. Using this strategy, major advances have occurred in the treatment of women with ovarian cancer who have defects in the Homologous Recombination Repair (HRR) pathway. When the HRR pathway is defective, due to mutations or epigenetic changes in genes such as BRCA1 or BRCA2, cells can no longer accurately repair double strand breaks (DSBs). Capitalising on this weakness, pharmacological inhibition of poly (ADP-ribose) polymerase (PARP) that function to repair single strand breaks (SSBs) leads to synthetic lethality in cells with defective HRR. PARP inhibitors (PARPis) including olaparib, niraparib and rucaparib are approved for the clinical management of women with ovarian cancer. Understanding and overcoming issues of acquired resistance to PARPis, extending these strategies to benefit more patients and combining PARPis with other drugs, including immunotherapies, are of high priority in the field today.

Abstract

The advent of molecular targeted therapies has made a significant impact on survival of women with ovarian cancer who have defects in homologous recombination repair (HRR). High-grade serous ovarian cancer (HGSOC) is the most common histological subtype of ovarian cancer, with over 50% displaying defective HRR. Poly ADP ribose polymerases (PARPs) are a family of enzymes that catalyse the transfer of ADP-ribose to target proteins, functioning in fundamental cellular processes including transcription, chromatin remodelling and DNA repair. In cells with deficient HRR, PARP inhibitors (PARPis) cause synthetic lethality leading to cell death. Despite the major advances that PARPis have heralded for women with ovarian cancer, questions and challenges remain, including: can the benefits of PARPis be brought to a wider range of women with ovarian cancer; can other drugs in clinical use function in a similar way or with greater efficacy than currently clinically approved PARPis; what can we learn from long-term responders to PARPis; can PARPis sensitise ovarian cancer cells to immunotherapy; and can synthetic lethal strategies be employed more broadly to develop new therapies for women with ovarian cancer. We examine these, and other, questions with focus on improving outcomes for women with ovarian cancer.

Tackling drug resistance in ovarian cancer with epigenetic targeted drugs

Epigenetic dysregulation plays a crucial role in the development and progression of ovarian cancer. Since the first experiment conducted on resistant ovarian cancer cells using demethylating drugs, multiple clinical trials have revealed that epigenetic targeted drugs combined with chemotherapy, molecular-targeted drugs, or even immunotherapy could enhance tumor sensitivity and reverse acquired resistances. Here, we summarized the combination strategies of epigenetic targeted drugs with other treatment strategies of ovarian cancer and discussed the principles of combination therapy. Finally, we enumerated several reasonable clinical trial designs as well as future drug development strategies, which may provide promising ideas for the application of epigenetic drugs to ovarian cancer.

TNKS inhibitors potentiate proliferative inhibition of BET inhibitors via reducing β-Catenin in colorectal cancer cells

Colorectal cancer (CRC) is an aggressive malignancy with limited options for treatment. Targeting the bromodomain and extra terminal domain (BET) proteins by using BET inhibitors (BETis) could effectively interrupt the interaction with acetylated histones, inhibit genes transcription and have shown a certain effect on CRC inhibition. To improve the efficacy, the inhibitors of Tankyrases, which cause accumulation of AXIN through dePARsylation, in turn facilitate the degradation of β-Catenin and suppress the growth of adenomatous polyposis coli (APC)-mutated CRCs, were tested together with BETi as a combination treatment. We examined the effects of BETi and Tankyrases inhibitor (TNKSi) together on the proliferation, cell cycle and apoptosis of human CRCs cell lines with APC or CTNNB1 mutation, and elucidated the underlying molecular mechanisms affected by the double treatment. The result showed that the TNKSi could sensitize all tested CRC cell lines to BETi, and the synergistic effect was not only seen in cell proliferation inhibition, but also confirmed in decreased colony-forming ability and weaken EdU incorporation compared with monotherapy. Combined treatment resulted in enhanced G1 cell cycle arrest and increased apoptosis. In addition, we found β-Catenin was potentially inhibited by the combination and revealed that both BETi-induced transcriptional inhibition and TNKSi-mediated protein degradation all reduced the β-Catenin accumulation. In all, the synergistic effects suggest that combination of BETi and TNKSi could provide novel treatment opportunities for CRC, but both TNKSi and combination strategy need to be optimized.

Dual-target inhibitors based on PARP1: new trend in the development of anticancer research

PARP1 is a hot target, and its inhibitors have been approved for cancer therapy. However, some undesirable properties restrict the application of PARP1 inhibitors, including drug resistance, side effects and low efficiency. For multifactorial diseases, dual-target drugs have exhibited excellent synergistic effects, such as reduced drug resistance, low side effects and high therapeutic efficacy, by simultaneously regulating the main pathogenic and compensatory signal pathways of diseases. In recent years, several dual-target inhibitors based on PARP1 have been reported and have demonstrated unique advantages. In this review we summarize the research progress in dual-target inhibitors based on PARP1 and discuss the related drug design strategies and structure-activity relationships. This work is expected to provide references for the development of PARP1 inhibitors.

pH-Responsive Hyaluronic Acid Nanoparticles for Enhanced Triple Negative Breast Cancer Therapy

Purpose

Methods

Results

Conclusion

The role of protein acetylation in carcinogenesis and targeted drug discovery

Protein acetylation is a reversible post-translational modification, and is involved in many biological processes in cells, such as transcriptional regulation, DNA damage repair, and energy metabolism, which is an important molecular event and is associated with a wide range of diseases such as cancers. Protein acetylation is dynamically regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs) in homeostasis. The abnormal acetylation level might lead to the occurrence and deterioration of a cancer, and is closely related to various pathophysiological characteristics of a cancer, such as malignant phenotypes, and promotes cancer cells to adapt to tumor microenvironment. Therapeutic modalities targeting protein acetylation are a potential therapeutic strategy. This article discussed the roles of protein acetylation in tumor pathology and therapeutic drugs targeting protein acetylation, which offers the contributions of protein acetylation in clarification of carcinogenesis, and discovery of therapeutic drugs for cancers, and lays the foundation for precision medicine in oncology.

Low Expression of SLC7A11 Confers Drug Resistance and Worse Survival in Ovarian Cancer via Inhibition of Cell Autophagy as a Competing Endogenous RNA

Drug resistance is the main cause of chemotherapy failure in ovarian cancer (OC), and identifying potential druggable targets of autophagy is a novel and promising approach to overcoming drug resistance. In this study, 131 genes associated with autophagy were identified from three autophagy-related databases, and of these, 14 were differentially expressed in 90 drug-resistant OC tissues versus 197 sensitive tissues according to the Cancer Genome Atlas ovarian cancer cohort. Among these 14 genes, SLC7A11 was significantly decreased in two paclitaxel-resistant OC cells (HeyA8-R and SKOV3-R) and in 90 drug-resistant tissues compared with their controls. In vitro overexpression of SLC7A11 significantly increased the sensitivity of HeyA8-R cells to paclitaxel, inhibited colony formation, induced apoptosis, and arrested cell cycle. Further, low SLC7A11 expression was correlated with poor overall survival (OS), progression-free survival (PFS), and post-progression survival (PPS) in 1815 OC patients. Mechanistically, SLC7A11 strongly regulated cell autophagy as a competing endogenous RNA (ceRNA) based on pan-cancer analyses of 32 tumor types. Specifically, as a ceRNA for autophagy genes STX17, RAB33B, and UVRAG, SLC7A11 was strongly and positively co-expressed with these three genes in 20, 12, and 12 different tumors, respectively, in 379 OC tissues and in 90 drug-resistant OC tissues, and the former two were significantly upregulated in SLC7A11-overexpressed HeyA8-R cells. Further, SLC7A11 induced the protein expression of other autophagy genes, such as LC3, Atg16L1, and Atg7, and the expression of the respective proteins was further increased when the cells were treated with paclitaxel. The results strongly suggest that SLC7A11 regulates autophagy via ceRNA interactions with the three abovementioned genes in pan-cancer and in drug-resistant OC. Moreover, low expression of STX17 and UVRAG also significantly predicted low OS, PFS, and PPS. The combination of SLC7A11 with STX17 was more predictive of OS and PFS than either individually, and the combination of SLC7A11 with UVRAG was highly predictive of OS and PPS. The above results indicated that decreased SLC7A11 resulted in drug resistance and effected low rates of survival in OC patients, probably via ceRNA interactions with autophagy genes, and thus the gene could serve as a therapeutic target and potential biomarker in OC.

Synergistic AHR Binding Pathway with EMT Effects on Serous Ovarian Tumors Recognized by Multidisciplinary Integrated Analysis

Epithelial ovarian cancers (EOCs) are fatal and obstinate among gynecological malignancies in advanced stage or relapsed status, with serous carcinomas accounting for the vast majority. Unlike EOCs, borderline ovarian tumors (BOTs), including serous BOTs, maintain a semimalignant appearance. Using gene ontology (GO)-based integrative analysis, we analyzed gene set databases of serous BOTs and serous ovarian carcinomas for dysregulated GO terms and pathways and identified multiple differentially expressed genes (DEGs) in various aspects. The SRC (SRC proto-oncogene, non-receptor tyrosine kinase) gene and dysfunctional aryl hydrocarbon receptor (AHR) binding pathway consistently influenced progression-free survival and overall survival, and immunohistochemical staining revealed elevated expression of related biomarkers (SRC, ARNT, and TBP) in serous BOT and ovarian carcinoma samples. Epithelial-mesenchymal transition (EMT) is important during tumorigenesis, and we confirmed the SNAI2 (Snail family transcriptional repressor 2, SLUG) gene showing significantly high performance by immunohistochemistry. During serous ovarian tumor formation, activated AHR in the cytoplasm could cooperate with SRC, enter cell nuclei, bind to AHR nuclear translocator (ARNT) together with TATA-Box Binding Protein (TBP), and act on DNA to initiate AHR-responsive genes to cause tumor or cancer initiation. Additionally, SNAI2 in the tumor microenvironment can facilitate EMT accompanied by tumorigenesis. Although it has not been possible to classify serous BOTs and serous ovarian carcinomas as the same EOC subtype, the key determinants of relevant DEGs (SRC, ARNT, TBP, and SNAI2) found here had a crucial role in the pathogenetic mechanism of both tumor types, implying gradual evolutionary tendencies from serous BOTs to ovarian carcinomas. In the future, targeted therapy could focus on these revealed targets together with precise detection to improve therapeutic effects and patient survival rates.

Strategies in Overcoming Homologous Recombination Proficiency and PARP Inhibitor Resistance

Ovarian cancer is the second most common gynecologic malignancy in the United States and the most common cause of gynecologic cancer-related death. The majority of ovarian cancers ultimately recur despite excellent response rates to upfront platinum- and taxane-based chemotherapy. Maintenance therapy after frontline treatment has emerged in recent years as an effective tool for extending the platinum-free interval of these patients. Maintenance therapy with PARP inhibitors (PARPis), in particular, has become part of standard of care in the upfront setting and in patients with platinum-sensitive disease. Homologous recombination deficient (HRD) tumors have a nonfunctioning homologous recombination repair (HRR) pathway and respond well to PARPis, which takes advantage of synthetic lethality by concomitantly impairing DNA repair mechanisms. Conversely, patients with a functioning HRR pathway, that is, HR-proficient tumors, can still elicit benefit from PARPi, but the efficacy is not as remarkable as what is seen in HRD tumors. PARPis are ineffective in some patients due to HR proficiency, which is either inherent to the tumor or potentially acquired as a method of therapeutic resistance. This review seeks to outline current strategies employed by clinicians and scientists to overcome PARPi resistance-either acquired or inherent to the tumor.

An expanded universe of cancer targets

The characterization of cancer genomes has provided insight into somatically altered genes across tumors, transformed our understanding of cancer biology, and enabled tailoring of therapeutic strategies. However, the function of most cancer alleles remains mysterious, and many cancer features transcend their genomes. Consequently, tumor genomic characterization does not influence therapy for most patients. Approaches to understand the function and circuitry of cancer genes provide complementary approaches to elucidate both oncogene and non-oncogene dependencies. Emerging work indicates that the diversity of therapeutic targets engendered by non-oncogene dependencies is much larger than the list of recurrently mutated genes. Here we describe a framework for this expanded list of cancer targets, providing novel opportunities for clinical translation.

Histone Modifying Enzymes in Gynaecological Cancers

Simple Summary

Epigenetics is a process that allows genetic control, without the involvement of sequence changes to DNA or genes. In cancer, epigenetics is a key event in tumour development that can alter the expression of cancer driver genes and result in genomic instability. Due to the critical role of epigenetics in malignant transformation, therapies that target these processes have been developed to treat cancer. Here, we provide a summary of the epigenetic changes that have been described in a variety of gynaecological cancers. We then highlight how these changes are being targeted in preclinical models and clinical trials for gynaecological cancers.

Abstract

Genetic and epigenetic factors contribute to the development of cancer. Epigenetic dysregulation is common in gynaecological cancers and includes altered methylation at CpG islands in gene promoter regions, global demethylation that leads to genome instability and histone modifications. Histones are a major determinant of chromosomal conformation and stability, and unlike DNA methylation, which is generally associated with gene silencing, are amenable to post-translational modifications that induce facultative chromatin regions, or condensed transcriptionally silent regions that decondense resulting in global alteration of gene expression. In comparison, other components, crucial to the manipulation of chromatin dynamics, such as histone modifying enzymes, are not as well-studied. Inhibitors targeting DNA modifying enzymes, particularly histone modifying enzymes represent a potential cancer treatment. Due to the ability of epigenetic therapies to target multiple pathways simultaneously, tumours with complex mutational landscapes affected by multiple driver mutations may be most amenable to this type of inhibitor. Interrogation of the actionable landscape of different gynaecological cancer types has revealed that some patients have biomarkers which indicate potential sensitivity to epigenetic inhibitors. In this review we describe the role of epigenetics in gynaecological cancers and highlight how it may exploited for treatment.

Targeting BET Proteins BRD2 and BRD3 in Combination with PI3K-AKT Inhibition as a Therapeutic Strategy for Ovarian Clear Cell Carcinoma

Ovarian clear cell carcinoma (OCCC) is a rare, chemo-resistant subtype of ovarian cancer. To identify novel therapeutic targets and combination therapies for OCCC, we subjected a set of patient-derived ovarian cancer cell lines to arrayed high-throughput siRNA and drug screening. The results indicated OCCC cells are vulnerable to knockdown of epigenetic gene targets such as bromodomain and extra-terminal domain (BET) proteins BRD2 and BRD3. Subsequent RNA interference assays, as well as BET inhibitor treatments, validated these BET proteins as potential therapeutic targets. Because development of resistance to single targeted agents is common, we next performed sensitizer drug screens to identify potential combination therapies with the BET inhibitor CPI0610. Several PI3K or AKT inhibitors were among the top drug combinations identified and subsequent work showed CPI0610 synergized with alpelisib or MK2206 by inducing p53-independent apoptosis. We further verified synergy between CPI0610 and PI3K-AKT pathway inhibitors alpelisib, MK2206, or ipatasertib in tumor organoids obtained directly from patients with OCCC. These findings indicate further preclinical evaluation of BET inhibitors, alone or in combination with PI3K-AKT inhibitors for OCCC, is warranted.

Identification of a Five-Autophagy-Related-lncRNA Signature as a Novel Prognostic Biomarker for Hepatocellular Carcinoma

Although great progresses have been made in the diagnosis and treatment of hepatocellular carcinoma (HCC), its prognostic marker remains controversial. In this current study, weighted correlation network analysis and Cox regression analysis showed significant prognostic value of five autophagy-related long non-coding RNAs (AR-lncRNAs) (including TMCC1-AS1, PLBD1-AS1, MKLN1-AS, LINC01063, and CYTOR) for HCC patients from data in The Cancer Genome Atlas. By using them, we constructed a five-AR-lncRNA prognostic signature, which accurately distinguished the high- and low-risk groups of HCC patients. All of the five AR lncRNAs were highly expressed in the high-risk group of HCC patients. This five-AR-lncRNA prognostic signature showed good area under the curve (AUC) value (AUC = 0.751) for the overall survival (OS) prediction in either all HCC patients or HCC patients stratified according to several clinical traits. A prognostic nomogram with this five-AR-lncRNA signature predicted the 3- and 5-year OS outcomes of HCC patients intuitively and accurately (concordance index = 0.745). By parallel comparison, this five-AR-lncRNA signature has better prognosis accuracy than the other three recently published signatures. Furthermore, we discovered the prediction ability of the signature on therapeutic outcomes of HCC patients, including chemotherapy and immunotherapeutic responses. Gene set enrichment analysis and gene mutation analysis revealed that dysregulated cell cycle pathway, purine metabolism, and TP53 mutation may play an important role in determining the OS outcomes of HCC patients in the high-risk group. Collectively, our study suggests a new five-AR-lncRNA prognostic signature for HCC patients.