Novel factors of cisplatin resistance in epithelial ovarian tumours

Ovarian tumours are these days one of the biggest oncogynecological problems. In addition to surgery, the treatment of ovarian cancer includes also chemotherapy in which platinum preparations are one of the most used chemotherapeutic drugs. The principle of antineoplastic effects of cisplatin (cis-diamminedichloroplatinum(II), CDDP) is its binding to the DNA and the formation of adducts. While DNA adducts induce the process of apoptosis, or inhibit the process of DNA replication, which prevents further division of tumour cells, various molecular mechanisms can reverse this process. On the other hand, with increasing scientific knowledge, it is becoming clearer that chemotherapy resistance is a very complex process. In this regard, factors and the amount of their expression may regulate the effect of resistance to chemotherapy. This review focuses on new molecular mechanisms and factors such as mitochondrial dynamics, epithelial-mesenchymal transition (EMT), cluster of differentiation, exosomes and others, that could be involved in the emergence of CDDP resistance.

MYC-dependent MiR-7-5p regulated apoptosis and autophagy in diffuse large B cell lymphoma by targeting AMBRA1

Diffuse large B-cell lymphoma (DLBCL) is the leading cause of mortality from invasive hematological malignancies worldwide. MicroRNA-7-5p (miR-7-5p) has been shown to be a tumor suppressor in several types of tumors. However, its role in DLBCL is not fully understood. This study explored the role of miR-7-5p in the progression of DLBCL and pursued the underlying mechanism. Quantitative real-time PCR and transfection of miRNA mimic and inhibitors were used to assess the effects of miR-7-5p on autophagy and apoptosis in SU-DHL-4 and SU-DHL-10 cells. Dual-luciferase reporter assay was used to identify target genes of miR-7-5p. Immunofluorescence, flow cytometry, and western blotting (WB) were performed to explore the underlying mechanism and downstream pathways of miR-7-5p and AMBRA1 in DLBCL cells. MiR-7-5p was upregulated in DLBCL cells. Luciferase reporter assays implicated AMBRA1 as a downstream target of miR-7-5p in DLBCL. WB and flow cytometry showed that an increase in miR-7-5p level and a decrease in AMBRA1 expression led to a decrease in autophagy and apoptosis-related protein expression. Furthermore, miR-7-5p prevented c-MYC dephosphorylation through AMBRA1 downregulation. On the contrary, c-MYC increased the expression of miR-7-5p, thereby establishing positive feedback on miR-7-5p transcription. The addition of hydroxychloroquine, an autophagy inhibitor, reduced autophagy and increased apoptosis in DLBCL cells. In vivo experiments further proved that the increase of miR-7-5p played a regulatory role in the expression of downstream AMBRA1 and c-MYC. These results demonstrate that c-MYC-dependent MiR-7-5p suppressed autophagy and apoptosis by targeting AMBRA1 in DLBCL cells. MiR-7-5p also suppressed autophagy and apoptosis by targeting AMBRA1 in DLBCL cells. Therefore, these data suggest that targeting miR-7-5p may be a promising strategy in DLBCL therapy.

Nanoliposomes as nonviral vectors in cancer gene therapy

Nonviral vectors, such as liposomes, offer potential for targeted gene delivery in cancer therapy. Liposomes, composed of phospholipid vesicles, have demonstrated efficacy as nanocarriers for genetic tools, addressing the limitations of off-targeting and degradation commonly associated with traditional gene therapy approaches. Due to their biocompatibility, stability, and tunable physicochemical properties, they offer potential in overcoming the challenges associated with gene therapy, such as low transfection efficiency and poor stability in biological fluids. Despite these advancements, there remains a gap in understanding the optimal utilization of nanoliposomes for enhanced gene delivery in cancer treatment. This review delves into the present state of nanoliposomes as carriers for genetic tools in cancer therapy, sheds light on their potential to safeguard genetic payloads and facilitate cell internalization alongside the evolution of smart nanocarriers for targeted delivery. The challenges linked to their biocompatibility and the factors that restrict their effectiveness in gene delivery are also discussed along with exploring the potential of nanoliposomes in cancer gene therapy strategies by analyzing recent advancements and offering future directions.

Autophagy-driven regulation of cisplatin response in human cancers: Exploring molecular and cell death dynamics

Despite the challenges posed by drug resistance and side effects, chemotherapy remains a pivotal strategy in cancer treatment. A key issue in this context is macroautophagy (commonly known as autophagy), a dysregulated cell death mechanism often observed during chemotherapy. Autophagy plays a cytoprotective role by maintaining cellular homeostasis and recycling organelles, and emerging evidence points to its significant role in promoting cancer progression. Cisplatin, a DNA-intercalating agent known for inducing cell death and cell cycle arrest, often encounters resistance in chemotherapy treatments. Recent studies have shown that autophagy can contribute to cisplatin resistance or insensitivity in tumor cells through various mechanisms. This resistance can be mediated by protective autophagy, which suppresses apoptosis. Additionally, autophagy-related changes in tumor cell metastasis, particularly the induction of Epithelial-Mesenchymal Transition (EMT), can also lead to cisplatin resistance. Nevertheless, pharmacological strategies targeting the regulation of autophagy and apoptosis offer promising avenues to enhance cisplatin sensitivity in cancer therapy. Notably, numerous non-coding RNAs have been identified as regulators of autophagy in the context of cisplatin chemotherapy. Thus, therapeutic targeting of autophagy or its associated pathways holds potential for restoring cisplatin sensitivity, highlighting an important direction for future clinical research.

Structure of the DDB1-AMBRA1 E3 ligase receptor complex linked to cell cycle regulation

AMBRA1 is a tumor suppressor protein that functions as a substrate receptor of the ubiquitin conjugation system with roles in autophagy and the cell cycle regulatory network. The intrinsic disorder of AMBRA1 has thus far precluded its structural determination. To solve this problem, we analyzed the dynamics of AMBRA1 using hydrogen deuterium exchange mass spectrometry (HDX-MS). The HDX results indicated that AMBRA1 is a highly flexible protein and can be stabilized upon interaction with DDB1, the adaptor of the Cullin4A/B E3 ligase. Here, we present the cryo-EM structure of AMBRA1 in complex with DDB1 at 3.08 Å resolution. The structure shows that parts of the N- and C-terminal structural regions in AMBRA1 fold together into the highly dynamic WD40 domain and reveals how DDB1 engages with AMBRA1 to create a binding scaffold for substrate recruitment. The N-terminal helix-loop-helix motif and WD40 domain of AMBRA1 associate with the double-propeller fold of DDB1. We also demonstrate that DDB1 binding-defective AMBRA1 mutants prevent ubiquitination of the substrate Cyclin D1 in vitro and increase cell cycle progression. Together, these results provide structural insights into the AMBRA1-ubiquitin ligase complex and suggest a mechanism by which AMBRA1 acts as a hub involved in various physiological processes.

AMBRA1 and its role as a target for anticancer therapy

The activating molecule in Beclin1-regulated autophagy protein 1 (AMBRA1) is an intrinsically disordered protein that regulates the survival and death of cancer cells by modulating autophagy. Although the roles of autophagy in cancer are controversial and context-dependent, inhibition of autophagy under some circumstances can be a useful strategy for cancer therapy. As AMBRA1 is a pivotal autophagy-associated protein, targeting AMBRA1 similarly may be an underlying strategy for cancer therapy. Emerging evidence indicates that AMBRA1 can also inhibit cancer formation, maintenance, and progression by regulating c-MYC and cyclins, which are frequently deregulated in human cancer cells. Therefore, AMBRA1 is at the crossroad of autophagy, tumorigenesis, proliferation, and cell cycle. In this review, we focus on discussing the mechanisms of AMBRA1 in autophagy, mitophagy, and apoptosis, and particularly the roles of AMBRA1 in tumorigenesis and targeted therapy.

Ambra1 in cancer: implications for clinical oncology

Activating molecule in Beclin-1-regulated autophagy protein 1 (Ambra1) is well known to mediate the autophagy process and promote the formation of autophagosomes. In addition, Ambra1 is involved in the execution of apoptosis. A growing number of studies have revealed that this protein modifies the sensitivity of cancer cells to anticancer drugs by controlling the balance between autophagy and apoptosis. In addition, Ambra1 is a key factor in regulating the cell cycle, proliferation, invasion and migration. Therefore, it plays a key role in tumorigenesis and progression. Moreover, Ambra1 is highly expressed in a variety of cancers and is closely related to the prognosis of patients. Thus, it appears that Ambra1 has multiple roles in tumorigenesis and progression, which may have implications for clinical oncology. The present review focuses on recent advances in the study of Ambra1, especially the role of the protein in tumorigenesis, progression and effects on anticancer drug sensitivity.

Is Autophagy Always a Barrier to Cisplatin Therapy?

Cisplatin has long been a first-line chemotherapeutic agent in the treatment of cancer, largely for solid tumors. During the course of the past two decades, autophagy has been identified in response to cancer treatments and almost uniformly detected in studies involving cisplatin. There has been increasing recognition of autophagy as a critical factor affecting tumor cell death and tumor chemoresistance. In this review and commentary, we introduce four mechanisms of resistance to cisplatin followed by a discussion of the factors that affect the role of autophagy in cisplatin-sensitive and resistant cells and explore the two-sided outcomes that occur when autophagy inhibitors are combined with cisplatin. Our goal is to analyze the potential for the combinatorial use of cisplatin and autophagy inhibitors in the clinic.

AMBRA1 promotes apoptosis induced by dsRNA and virus through interacting with and stabilizing MAVS

Apoptosis is an important cellular response to viral infection. In current study, we identified activating molecule in Beclin1-regulated autophagy protein 1 (AMBRA1) as a positive regulator of apoptosis triggered by dsRNA. Depletion of AMBRA1 by gene editing significantly reduced dsRNA-induced apoptosis, which was largely restored by trans-complementation of AMBRA1. Mechanistically, AMBRA1 interacts with mitochondrial antiviral-signaling protein (MAVS), a key mitochondrial adaptor in the apoptosis pathway induced by dsRNA and viral infection. Further Co-IP analysis demonstrated that the mitochondrial localization of MAVS was essential for their interaction. The impact of AMBRA1 on dsRNA-induced apoptosis relied on the presence of MAVS and caspase-8. AMBRA1 was involved in the stabilization of MAVS through preventing its proteasomal degradation induced by dsRNA. Consistently, AMBRA1 upregulated the apoptosis induced by Semliki Forest virus infection. Taken together, our work illustrated a role of AMBRA1 in the virus-induced apoptosis through interacting with and stabilizing MAVS.

A Genome-Wide Profiling of Glioma Patients with an IDH1 Mutation Using the Catalogue of Somatic Mutations in Cancer Database

Simple Summary

Glioma patients that present a somatic mutation in the isocitrate dehydrogenase 1 (IDH1) gene have a significantly better prognosis and overall survival than patients with the wild-type genotype. An IDH1 mutation is hypothesized to occur early during cellular transformation and leads to further genetic instability. A genome-wide profiling of glioma patients in the Catalogue of Somatic Mutations in Cancer (COSMIC) database was performed to classify the genetic differences in IDH1-mutant versus IDH1-wildtype patients. This classification will aid in a better understanding of how this specific mutation influences the genetic make-up of glioma and the resulting prognosis. Key differences in co-mutation and gene expression levels were identified that correlate with an improved prognosis.

Abstract

Gliomas are differentiated into two major disease subtypes, astrocytoma or oligodendroglioma, which are then characterized as either IDH (isocitrate dehydrogenase)-wild type or IDH-mutant due to the dramatic differences in prognosis and overall survival. Here, we investigated the genetic background of IDH1-mutant gliomas using the Catalogue of Somatic Mutations in Cancer (COSMIC) database. In astrocytoma patients, we found that IDH1 is often co-mutated with TP53, ATRX, AMBRA1, PREX1, and NOTCH1, but not CHEK2, EGFR, PTEN, or the zinc finger transcription factor ZNF429. The majority of the mutations observed in these genes were further confirmed to be either drivers or pathogenic by the Cancer-Related Analysis of Variants Toolkit (CRAVAT). Gene expression analysis showed down-regulation of DRG2 and MSN expression, both of which promote cell proliferation and invasion. There was also significant over-expression of genes such as NDRG3 and KCNB1 in IDH1-mutant astrocytoma patients. We conclude that IDH1-mutant glioma is characterized by significant genetic changes that could contribute to a better prognosis in glioma patients.

The Multifaceted Effects of Autophagy on the Tumor Microenvironment

The tumor microenvironment is composed of cancer cells, noncancer cells (e.g., immune cells, stromal cells, endothelial cells, and adipocytes), and various mediators (e.g., cytokines, chemokines, growth factors, and humoral factors) that work together to support cancer growth, progression, and resistance to therapies. Autophagy is an evolutionarily conserved degradation mechanism by which various cytosolic cargos (e.g., damaged organelles, unused molecules, or invaded pathogens) are engulfed by double-membrane autophagosomes, and then delivered into the lysosome for degradation and recycling. The level of autophagy is a crucial threshold to either promote cell survival or induce cell death in response to environmental stresses. Autophagy plays a context-dependent role in tumorigenesis and anticancer therapy via shaping the inflammatory, hypoxic, immunosuppressive, and metabolic tumor microenvironment. In particular, impaired autophagy flux is associated with chronic inflammation, immunosuppression, stromal formation, cancer stemness, angiogenesis, metastasis, and metabolic reprogramming in the tumor microenvironment. Understanding the molecular machinery of autophagy and its communication with hallmarks of cancer could lead to potential new anticancer strategies or drugs.

Transposon Insertion Mutagenesis in Mice for Modeling Human Cancers: Critical Insights Gained and New Opportunities

Transposon mutagenesis has been used to model many types of human cancer in mice, leading to the discovery of novel cancer genes and insights into the mechanism of tumorigenesis. For this review, we identified over twenty types of human cancer that have been modeled in the mouse using Sleeping Beauty and piggyBac transposon insertion mutagenesis. We examine several specific biological insights that have been gained and describe opportunities for continued research. Specifically, we review studies with a focus on understanding metastasis, therapy resistance, and tumor cell of origin. Additionally, we propose further uses of transposon-based models to identify rarely mutated driver genes across many cancers, understand additional mechanisms of drug resistance and metastasis, and define personalized therapies for cancer patients with obesity as a comorbidity.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.

Identifying synthetic lethal targets using CRISPR/Cas9 system

Synthetic lethality occurs when co-occurrence of two genetic events is unfavorable for the survival of the cell or organism. The conventional approach of high throughput screening of synthetic lethal targets using chemical compounds has been replaced by RNAi technology. CRISPR/Cas9, an RNA guided endonuclease system is the most recent technology for this work. Here, we have discussed the major considerations involved in designing a CRISPR/Cas9 based screening experiment for identification of synthetic lethal targets. It mainly includes CRISPR library to be used, cell types for conducting the experiment, the most appropriate screening strategy and ways of selecting the desired phenotypes from the complete cell population. The complete knockdown of genes can be achieved using CRISPR/Cas9 knockout libraries. For higher quality loss-of-function screens, haploid cells with defective homology-directed DNA repair mechanism could be used. Two widely used screening formats include arrayed and pooled screens followed by negative or positive selection of the cells with desired phenotype. However, pooled screening format with negative selection of cells serves the best. The advantages of using CRISPR/Cas9 system over the other RNAi approaches have also been discussed. Finally, some studies using CRISPR/Cas9 for genome-wide knockout screening in human cells and computational approaches for identification of synthetic lethal interactions have been discussed.

Synthetic lethality in lung cancer and translation to clinical therapies

Lung cancer is a heterogeneous disease consisting of multiple histological subtypes each driven by unique genetic alterations. Despite the development of targeted therapies that inhibit the oncogenic mutations driving a subset of lung cancer cases, there is a paucity of effective treatments for the majority of lung cancer patients and new strategies are urgently needed. In recent years, the concept of synthetic lethality has been established as an effective approach for discovering novel cancer-specific targets as well as a method to improve the efficacy of existing drugs which provide partial but insufficient benefits for patients. In this review, we discuss the concept of synthetic lethality, the various types of synthetic lethal interactions in the context of oncology and the approaches used to identify these interactions, including recent advances that have transformed the ability to discover novel synthetic lethal combinations on a global scale. Lastly, we describe the specific synthetic lethal interactions identified in lung cancer to date and explore the pharmacological challenges and considerations in translating these discoveries to the clinic.

Molecular diagnosis and molecular profiling to detect treatment-resistant ovarian cancer

INTRODUCTION

Epithelial ovarian cancer remains the gynecologic tumor with the highest rate of recurrence after initial optimal cytoreductive surgery followed by adjuvant chemotherapy. Unfortunately, with the development of recurrent ovarian cancer often comes the discovery of chemo-resistant disease. The absence of improvement in long term survival, notwithstanding the use of newer agents as is seen in other cancers, emphasizes the need for improved understanding of the processes that lead to chemo-resistant disease.

AREAS COVERED

This review will cover the following topics: 1. Molecular and cellular mechanisms in platinum and paclitaxel resistance 2. Other molecular mediators of chemo-resistance 3. Expression of stem cell markers in ovarian cancer and relationship to chemo-resistance 4. MicroRNA and long non-coding RNA expression in chemo-resistant ovarian cancer 5. Determination of chromosomal aberrations as markers of chemo-resistance 6. Molecular profiling in chemo-resistant disease. A standard MEDLINE search was performed using the key words; ovarian cancer, chemo-resistant disease, molecular profiling, cancer stem cells and chemotherapy. Expert Commentary: Over the next few years the challenge remains to precisely determine the mechanisms responsible for the onset and maintenance of chemo-resistance and to effectively target these mechanisms.