FBXW7 in Cancer: What Has Been Unraveled Thus Far?

The SCF-FBW7β E3 ligase mediates ubiquitination and degradation of the serine/threonine protein kinase PINK1

Understanding the mechanisms that govern the stability of functionally crucial proteins is essential for various cellular processes, development, and overall cell viability. Disturbances in protein homeostasis are linked to the pathogenesis of neurodegenerative diseases. PTEN-induced kinase 1 (PINK1), a protein kinase, plays a significant role in mitochondrial quality control and cellular stress response, and its mutated forms lead to early-onset Parkinson's disease. Despite its importance, the specific mechanisms regulating PINK1 protein stability have remained unclear. This study reveals a cytoplasmic interaction between PINK1 and F-box and WD repeat domain-containing 7β (FBW7β) in mammalian cells. FBW7β, a component of the Skp1-Cullin-1-F-box protein complex-type ubiquitin ligase, is instrumental in recognizing substrates. Our findings demonstrate that FBW7β regulates PINK1 stability through the Skp1-Cullin-1-F-box protein complex and the proteasome pathway. It facilitates the K48-linked polyubiquitination of PINK1, marking it for degradation. When FBW7 is absent, PINK1 accumulates, leading to heightened mitophagy triggered by carbonyl cyanide 3-chlorophenylhydrazone treatment. Moreover, exposure to the toxic compound staurosporine accelerates PINK1 degradation via FBW7β, correlating with increased cell death. This study unravels the intricate mechanisms controlling PINK1 protein stability and sheds light on the novel role of FBW7β. These findings deepen our understanding of PINK1-related pathologies and potentially pave the way for therapeutic interventions.

Isoform alterations in the ubiquitination machinery impacting gastrointestinal malignancies

The advancement of RNAseq and isoform-specific expression platforms has led to the understanding that isoform changes can alter molecular signaling to promote tumorigenesis. An active area in cancer research is uncovering the roles of ubiquitination on spliceosome assembly contributing to transcript diversity and expression of alternative isoforms. However, the effects of isoform changes on functionality of ubiquitination machineries (E1, E2, E3, E4, and deubiquitinating (DUB) enzymes) influencing onco- and tumor suppressor protein stabilities is currently understudied. Characterizing these changes could be instrumental in improving cancer outcomes via the identification of novel biomarkers and targetable signaling pathways. In this review, we focus on highlighting reported examples of direct, protein-coded isoform variation of ubiquitination enzymes influencing cancer development and progression in gastrointestinal (GI) malignancies. We have used a semi-automated system for identifying relevant literature and applied established systems for isoform categorization and functional classification to help structure literature findings. The results are a comprehensive snapshot of known isoform changes that are significant to GI cancers, and a framework for readers to use to address isoform variation in their own research. One of the key findings is the potential influence that isoforms of the ubiquitination machinery have on oncoprotein stability.

Nephronophthisis-associated FBW7 mediates cyst-dependent decline of renal function in ADPKD

Nephronophthisis (NPHP) and autosomal dominant Polycystic Kidney Disease (ADPKD) are two genetically distinct forms of Polycystic Kidney Disease (PKD), yet both diseases present with kidney cysts and a gradual decline in renal function. Prevailing dogma in PKD is that changes in kidney architecture account for the decline in kidney function, but the molecular/cellular basis of such coupling is unknown. To address this question, we induced a form of proteome reprogramming by deleting Fbxw7 encoding FBW7, the recognition receptor of the SCF FBW7 E3 ubiquitin ligase in different segments of the kidney tubular system. Deletion of Fbxw7 in the medulla led to a juvenile-adult NPHP-like phenotype, where the decline in renal function was due to SOX9-mediated interstitial fibrosis rather than cystogenesis. In contrast, the decline of renal function in ADPKD is coupled to cystic expansion via the abnormal accumulation of FBW7 in the proximal tubules and other cell types in the renal cortex. We propose that FBW7 functions at the apex of a protein network that determines renal function in ADPKD by sensing architectural changes induced by cystic expansion.

Dormant cancer cells and polyploid giant cancer cells: The roots of cancer recurrence and metastasis

Tumour cell dormancy is critical for metastasis and resistance to chemoradiotherapy. Polyploid giant cancer cells (PGCCs) with giant or multiple nuclei and high DNA content have the properties of cancer stem cell and single PGCCs can individually generate tumours in immunodeficient mice. PGCCs represent a dormant form of cancer cells that survive harsh tumour conditions and contribute to tumour recurrence. Hypoxic mimics, chemotherapeutics, radiation and cytotoxic traditional Chinese medicines can induce PGCCs formation through endoreduplication and/or cell fusion. After incubation, dormant PGCCs can recover from the treatment and produce daughter cells with strong proliferative, migratory and invasive abilities via asymmetric cell division. Additionally, PGCCs can resist hypoxia or chemical stress and have a distinct protein signature that involves chromatin remodelling and cell cycle regulation. Dormant PGCCs form the cellular basis for therapeutic resistance, metastatic cascade and disease recurrence. This review summarises regulatory mechanisms governing dormant cancer cells entry and exit of dormancy, which may be used by PGCCs, and potential therapeutic strategies for targeting PGCCs.

Key Proteins of Replication Stress Response and Cell Cycle Control as Cancer Therapy Targets

Replication stress (RS) is a characteristic state of cancer cells as they tend to exchange precision of replication for fast proliferation and increased genomic instability. To overcome the consequences of improper replication control, malignant cells frequently inactivate parts of their DNA damage response (DDR) pathways (the ATM-CHK2-p53 pathway), while relying on other pathways which help to maintain replication fork stability (ATR-CHK1). This creates a dependency on the remaining DDR pathways, vulnerability to further destabilization of replication and synthetic lethality of DDR inhibitors with common oncogenic alterations such as mutations of TP53, RB1, ATM, amplifications of MYC, CCNE1 and others. The response to RS is normally limited by coordination of cell cycle, transcription and replication. Inhibition of WEE1 and PKMYT1 kinases, which prevent unscheduled mitosis entry, leads to fragility of under-replicated sites. Recent evidence also shows that inhibition of Cyclin-dependent kinases (CDKs), such as CDK4/6, CDK2, CDK8/19 and CDK12/13 can contribute to RS through disruption of DNA repair and replication control. Here, we review the main causes of RS in cancers as well as main therapeutic targets-ATR, CHK1, PARP and their inhibitors.

Inhibitors Targeting the F-BOX Proteins

F-box proteins are involved in multiple cellular processes through ubiquitylation and consequent degradation of targeted substrates. Any significant mutation in F-box protein-mediated proteolysis can cause human malformations. The various cellular processes F-box proteins involved include cell proliferation, apoptosis, invasion, angiogenesis, and metastasis. To target F-box proteins and their associated signaling pathways for cancer treatment, researchers have developed thousands of F-box inhibitors. The most advanced inhibitor of FBW7, NVD-BK M120, is a powerful P13 kinase inhibitor that has been proven to bring about apoptosis in cancerous human lung cells by disrupting levels of the protein known as MCL1. Moreover, F-box Inhibitors have demonstrated their efficacy for treating certain cancers through targeting particular mutated proteins. This paper explores the key studies on how F-box proteins act and their contribution to malignancy development, which fabricates an in-depth perception of inhibitors targeting the F-box proteins and their signaling pathways that eventually isolate the most promising approach to anti-cancer treatments.

FBXW7 and human tumors: mechanisms of drug resistance and potential therapeutic strategies

Drug therapy, including chemotherapy, targeted therapy, immunotherapy, and endocrine therapy, stands as the foremost therapeutic approach for contemporary human malignancies. However, increasing drug resistance during antineoplastic therapy has become a substantial barrier to favorable outcomes in cancer patients. To enhance the effectiveness of different cancer therapies, an in-depth understanding of the unique mechanisms underlying tumor drug resistance and the subsequent surmounting of antitumor drug resistance is required. Recently, F-box and WD Repeat Domain-containing-7 (FBXW7), a recognized tumor suppressor, has been found to be highly associated with tumor therapy resistance. This review provides a comprehensive summary of the underlying mechanisms through which FBXW7 facilitates the development of drug resistance in cancer. Additionally, this review elucidates the role of FBXW7 in therapeutic resistance of various types of human tumors. The strategies and challenges implicated in overcoming tumor therapy resistance by targeting FBXW7 are also discussed.

FBXW7 Enhances Cisplatin-Induced Apoptosis in Oral Cancer Cell Lines

BACKGROUND

About one-third of patients with oral squamous cell carcinoma (OSCC) have a risk of occurrence and chemoresistance, making survival rates abysmal. We aim to evaluate the role of F-box/WD repeat-containing protein 7 (FBXW7) to further develop efficient treatment of chemoresistant OSCC.

METHODS

FBXW7 overexpression was induced in human OSCC cell lines including SCC9 and CAL27 by a lentiviral vector, Lv-FBXW7 or lv-NC (noncoding control), and overexpression efficiency was assessed using quantitative real-time polymerase chain reaction (qRT-PCR) and western blot of FBXW7. Cell viability was measured using MTT assay. The effects of FBXW7 overexpression on cell migration and invasion was evaluated by the colony formation assay and Matrigel assay. Apoptosis of cells with lv-FBXW7 transfection was measured by qRT-PCR and western blot analyses of BAX, BAK, MCL1, and BCL2 expression. Growth rate and cisplatin sensitivity of CAL27 xenografts with or without FBXW7 overexpression was monitored. Ki-67 and PCMA levels-which are biomarkers of intratumoural apoptosis-BAX, MCL1, Beclin1, and LC3I&II-which are autophagy biomarkers-were assessed.

RESULTS

Transfection of lv-FBXW7 in SCC9 and CAL27 cells resulted in increased sensitivity to cisplatin treatment, as evidenced by slower cell proliferation, lower colony formation and invasion, higher apoptosis, and autophagy compared to those transfected with lv-NC. Mice with CAL27 xenografts overexpressing FBXW7 also demonstrated slower tumour growth and upregulation in Ki067 and PCNA. Tumours also showed higher apoptosis and autophagy activities.

CONCLUSIONS

FBXW7 overexpression was herein shown to effectively sensitise OSCC cells to cisplatin treatment in vitro and in vivo.

Predator: Predicting the Impact of Cancer Somatic Mutations on Protein-Protein Interactions

Since many biological processes are governed by protein-protein interactions, understanding which mutations lead to a disruption in these interactions is profoundly important for cancer research. Most of the existing methods focus on the stability of the protein without considering the specific effects of a mutation on its interactions with other proteins. Here, we focus on somatic mutations that appear on the interface regions of the protein and predict the interactions that would be affected by a mutation of interest. We build an ensemble model, Predator, that classifies the interface mutations as disruptive or nondisruptive based on the predicted effects of mutations on specific protein-protein interactions. We show that Predator outperforms existing approaches in literature in terms of prediction accuracy. We then apply Predator on various TCGA cancer cohorts and perform comprehensive analysis at cohort level, patient level, and gene level in determining the genes whose interface mutations tend to yield a disruption in its interactions. The predictions obtained by Predator shed light on interesting patterns on several genes for each cohort regarding their potential as cancer drivers. Our analyses further reveal that the identified genes and their frequently disrupted partners exhibit patterns of mutually exclusivity across cancer cohorts under study.

FBXW7β loss-of-function enhances FASN-mediated lipogenesis and promotes colorectal cancer growth

Continuous de novo fatty acid synthesis is required for the biosynthetic demands of tumor. FBXW7 is a highly mutated gene in CRC, but its biological functions in cancer are not fully characterized. Here, we report that FBXW7β, a FBXW7 isoform located in the cytoplasm and frequently mutated in CRC, is an E3 ligase of fatty acid synthase (FASN). Cancer-specific FBXW7β mutations that could not degrade FASN can lead to sustained lipogenesis in CRC. COP9 signalosome subunit 6 (CSN6), an oncogenic marker of CRC, increases lipogenesis via interacting with and stabilizing FASN. Mechanistic studies show that CSN6 associates with both FBXW7β and FASN, and antagonizes FBXW7β's activity by enhancing FBXW7β autoubiquitination and degradation, which in turn prevents FBXW7β-mediated FASN ubiquitination and degradation, thereby regulating lipogenesis positively. Both CSN6 and FASN are positively correlated in CRC, and CSN6-FASN axis, regulated by EGF, is responsible for poor prognosis of CRC. The EGF-CSN6-FASN axis promotes tumor growth and implies a treatment strategy of combination of orlistat and cetuximab. Patient-derived xenograft experiments prove the effectiveness of employing orlistat and cetuximab combination in suppressing tumor growth for CSN6/FASN-high CRC. Thus, CSN6-FASN axis reprograms lipogenesis to promote tumor growth and is a target for cancer intervening strategy in CRC.

Research advances in endometriosis-related signaling pathways: A review

Endometriosis (EM) is characterized by the existence of endometrial mucosa outside the uterine cavity, which causesinfertility, persistent aches, and a decline in women's quality of life. Both hormone therapies and nonhormone therapies, such as NSAIDs, are ineffective, generic categories of EM drugs. Endometriosis is a benign gynecological condition, yet it shares a number of features with cancer cells, including immune evasion, survival, adhesion, invasion, and angiogenesis. Several endometriosis-related signaling pathways are comprehensively reviewed in this article, including E2, NF-κB, MAPK, ERK, PI3K/Akt/mTOR, YAP, Wnt/β-catenin, Rho/ROCK, TGF-β, VEGF, NO, iron, cytokines and chemokines. To find and develop novel medications for the treatment of EM, it is essential to implicitly determine the molecular pathways that are disordered during EM development. Additionally, research on the shared pathways between EM and tumors can provide hypotheses or suggestions for endometriosis therapeutic targets.

The Role of FBXW7 in Gynecologic Malignancies

The F-Box and WD Repeat Domain Containing 7 (FBXW7) protein has been shown to regulate cellular growth and act as a tumor suppressor. This protein, also known as FBW7, hCDC4, SEL10 or hAGO, is encoded by the gene FBXW7. It is a crucial component of the Skp1-Cullin1-F-box (SCF) complex, which is a ubiquitin ligase. This complex aids in the degradation of many oncoproteins, such as cyclin E, c-JUN, c-MYC, NOTCH, and MCL1, via the ubiquitin-proteasome system (UPS). The FBXW7 gene is commonly mutated or deleted in numerous types of cancer, including gynecologic cancers (GCs). Such FBXW7 mutations are linked to a poor prognosis due to increased treatment resistance. Hence, detection of the FBXW7 mutation may possibly be an appropriate diagnostic and prognostic biomarker that plays a central role in determining suitable individualized management. Recent studies also suggest that, under specific circumstances, FBXW7 may act as an oncogene. There is mounting evidence indicating that the aberrant expression of FBXW7 is involved in the development of GCs. The aim of this review is to give an update on the role of FBXW7 as a potential biomarker and also as a therapeutic target for novel treatments, particularly in the management of GCs.

The interplay of signaling pathways and miRNAs in the pathogenesis and targeted therapy of esophageal cancer

Globally, esophageal cancer (EC) is the 6th leading cause of cancer-related deaths and the second deadliest gastrointestinal cancer. Multiple genetic and epigenetic factors, such as microRNAs (miRNAs), influence its onset and progression. miRNAs are short nucleic acid molecules that can regulate multiple cellular processes by regulating gene expression. Therefore, EC initiation, progression, apoptosis evasions, invasion capacity, promotion, angiogenesis, and epithelial-mesenchymal transition (EMT) enhancement are associated with miRNA expression dysregulation. Wnt/-catenin signaling, Mammalian target of rapamycin (mTOR)/P-gp, phosphoinositide-3-kinase (PI3K)/AKT/c-Myc, epidermal growth factor receptor (EGFR), and transforming growth factor (TGF)-β signaling are crucial pathways in EC that are controlled by miRNAs. This review was conducted to provide an up-to-date assessment of the role of microRNAs in EC pathogenesis and their modulatory effects on responses to various EC treatment modalities.

Sensitization of colon cancer cells to cisplatin by Fbxw7 via negative regulation of the Nox1-mTOR pathway

Colorectal cancer (CRC) is a human malignancy which associates with high mortality rate and poor prognosis. Despite the initial effectiveness in clinical applications of chemotherapeutic agents, a fraction of patients develops chemoresistance. Fbxw7 is an F-box protein serving as a substrate recognition subunit of E3 ubiquitin ligase, leading to degradation of various oncoproteins. In this study, Fbxw7 was significantly downregulated in CRC tumors as well as CRC cells. Fbxw7 suppressed CRC cell proliferation and migration. Moreover, we observed Fbxw7 was positively associated with cisplatin sensitivity. Fbxw7 was significantly downregulated in cisplatin resistant CRC cells. Overexpression of Fbxw7 effectively increased the cisplatin sensitivity of cisplatin resistant CRC cells. Co-immunoprecipitation and GST pull-down assays showed Fbxw7 bond with Nox1 which was a superoxide-generating NADPH oxidase and showed oncogenic roles in colon cancer cells. Interestingly, Fbxw7 downregulated Nox1 through binding it to degrade Nox1 protein. We demonstrated that Fbxw7 negatively regulated mTOR activity through downregulation of Nox1. Finally, overexpression of Fbxw7 effectively increased the cisplatin sensitivity of CRC cells. This process could be further overturned by Nox1 restoration in Fbxw7-overexpressing colon cancer cells. In summary, these results unveiled that Fbxw7 targeted Nox1 for degradation, resulting in blocking the downstream Nox1-mTORC1 signaling to sensitize CRC cells to cisplatin. Our study potentiates that targeting the Fbxw7-Nox1-mTOR pathway could be an effective approach to overcome chemoresistance of colon cancer cells.

Epigenetic status of FBXW7 gene and its role in Ovarian cancer pathogenesis

BACKGROUND

Chromatin immunoprecipitation (ChIP) analysis revealed that the FBXW7 gene and the long non-coding RNA (LINC01588) are potential candidates in epithelial ovarian cancer (EOC) pathogenesis. However, their exact role in EOC is not yet known. Thus, the present study sheds light on the impact of the mutations/ methylation status of the FBXW7 gene.

MATERIALS AND METHODS

We used public databases to assess the correlation between mutations/ methylation status and the FBXW7 expression. Furthermore, we performed Pearson's correlation analysis between the FBXW7 gene and LINC01588. We performed gene panel exome sequencing and Methylation-specific PCR (MSP) in HOSE 6-3, MCAS, OVSAHO, and eight EOC patients' samples to validate the bioinformatics results.

RESULTS

The FBXW7 gene was less expressed in EOC, particularly in stages III and IV, compared to healthy tissues. Furthermore, bioinformatics analysis, gene panel exome sequencing, and MSP revealed that the FBXW7 gene is neither mutated nor methylated in EOC cell lines and tissues, suggesting alternative mechanisms for FBXW7 gene regulation. Interestingly, Pearson's correlation analysis showed an inverse, significant correlation between the FBXW7 gene and LINC01588  expression, suggesting a potential regulatory role of LINC01588.

CONCLUSION

Neither mutations nor methylation is the causative mechanism for the FBXW7 downregulation in EOC, suggesting alternative means involving the lncRNA LINC01588.

Role of Turmeric and Curcumin in Prevention and Treatment of Chronic Diseases: Lessons Learned from Clinical Trials

Turmeric (Curcuma longa) has been used for thousands of years for the prevention and treatment of various chronic diseases. Curcumin is just one of >200 ingredients in turmeric. Almost 7000 scientific papers on turmeric and almost 20,000 on curcumin have been published in PubMed. Scientific reports based on cell culture or animal studies are often not reproducible in humans. Therefore, human clinical trials are the best indicators for the prevention and treatment of a disease using a given agent/drug. Herein, we conducted an extensive literature survey on PubMed and Scopus following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The keywords "turmeric and clinical trials" and "curcumin and clinical trials" were considered for data mining. A total of 148 references were found to be relevant for the key term "turmeric and clinical trials", of which 70 were common in both PubMed and Scopus, 44 were unique to PubMed, and 34 were unique to Scopus. Similarly, for the search term "curcumin and clinical trials", 440 references were found to be relevant, of which 70 were unique to PubMed, 110 were unique to Scopus, and 260 were common to both databases. These studies show that the golden spice has enormous health and medicinal benefits for humans. This Review will extract and summarize the lessons learned about turmeric and curcumin in the prevention and treatment of chronic diseases based on clinical trials.

UBXN2A suppresses the Rictor-mTORC2 signaling pathway, an established tumorigenic pathway in human colorectal cancer

The mTORC2 pathway plays a critical role in promoting tumor progression in human colorectal cancer (CRC). The regulatory mechanisms for this signaling pathway are only partially understood. We previously identified UBXN2A as a novel tumor suppressor protein in CRCs and hypothesized that UBXN2A suppresses the mTORC2 pathway, thereby inhibiting CRC growth and metastasis. We first used murine models to show that haploinsufficiency of UBXN2A significantly increases colon tumorigenesis. Induction of UBXN2A reduces AKT phosphorylation downstream of the mTORC2 pathway, which is essential for a plethora of cellular processes, including cell migration. Meanwhile, mTORC1 activities remain unchanged in the presence of UBXN2A. Mechanistic studies revealed that UBXN2A targets Rictor protein, a key component of the mTORC2 complex, for 26S proteasomal degradation. A set of genetic, pharmacological, and rescue experiments showed that UBXN2A regulates cell proliferation, apoptosis, migration, and colon cancer stem cells (CSCs) in CRC. CRC patients with a high level of UBXN2A have significantly better survival, and high-grade CRC tissues exhibit decreased UBXN2A protein expression. A high level of UBXN2A in patient-derived xenografts and tumor organoids decreases Rictor protein and suppresses the mTORC2 pathway. These findings provide new insights into the functions of an ubiquitin-like protein by inhibiting a dominant oncogenic pathway in CRC.

Theranostic applications of selenium nanomedicines against lung cancer

The incidence and mortality rates of lung cancer are among the highest in the world. Traditional treatment methods include surgery, chemotherapy, and radiotherapy. Although rapid progress has been achieved in the past decade, treatment limitations remain. It is therefore imperative to identify safer and more effective therapeutic methods, and research is currently being conducted to identify more efficient and less harmful drugs. In recent years, the discovery of antitumor drugs based on the essential trace element selenium (Se) has provided good prospects for lung cancer treatments. In particular, compared to inorganic Se (Inorg-Se) and organic Se (Org-Se), Se nanomedicine (Se nanoparticles; SeNPs) shows much higher bioavailability and antioxidant activity and lower toxicity. SeNPs can also be used as a drug delivery carrier to better regulate protein and DNA biosynthesis and protein kinase C activity, thus playing a role in inhibiting cancer cell proliferation. SeNPs can also effectively activate antigen-presenting cells to stimulate cell immunity, exert regulatory effects on innate and regulatory immunity, and enhance lung cancer immunotherapy. This review summarizes the application of Se-based species and materials in lung cancer diagnosis, including fluorescence, MR, CT, photoacoustic imaging and other diagnostic methods, as well as treatments, including direct killing, radiosensitization, chemotherapeutic sensitization, photothermodynamics, and enhanced immunotherapy. In addition, the application prospects and challenges of Se-based drugs in lung cancer are examined, as well as their forecasted future clinical applications and sustainable development.

Advances in the potential roles of Cullin-RING ligases in regulating autoimmune diseases

Cullin-RING ligases (CRLs) are the largest class of E3 ubiquitin ligases regulating the stability and subsequent activity of a large number of important proteins responsible for the development and progression of various diseases, including autoimmune diseases (AIDs). However, the detailed mechanisms of the pathogenesis of AIDs are complicated and involve multiple signaling pathways. An in-depth understanding of the underlying regulatory mechanisms of the initiation and progression of AIDs will aid in the development of effective therapeutic strategies. CRLs play critical roles in regulating AIDs, partially by affecting the key inflammation-associated pathways such as NF-κB, JAK/STAT, and TGF-β. In this review, we summarize and discuss the potential roles of CRLs in the inflammatory signaling pathways and pathogenesis of AIDs. Furthermore, advances in the development of novel therapeutic strategies for AIDs through targeting CRLs are also highlighted.

FBXW7 attenuates tumor drug resistance and enhances the efficacy of immunotherapy

FBXW7 (F-box and WD repeat domain containing 7) is a critical subunit of the Skp1-Cullin1-F-box protein (SCF), acting as an E3 ubiquitin ligase by ubiquitinating targeted protein. Through degradation of its substrates, FBXW7 plays a pivotal role in drug resistance in tumor cells and shows the potential to rescue the sensitivity of cancer cells to drug treatment. This explains why patients with higher FBXW7 levels exhibit higher survival times and more favorable prognosis. Furthermore, FBXW7 has been demonstrated to enhance the efficacy of immunotherapy by targeting the degradation of specific proteins, as compared to the inactivated form of FBXW7. Additionally, other F-box proteins have also shown the ability to conquer drug resistance in certain cancers. Overall, this review aims to explore the function of FBXW7 and its specific effects on drug resistance in cancer cells.

Withaferin A: A Pleiotropic Anticancer Agent from the Indian Medicinal Plant Withania somnifera (L.) Dunal

Cancer represents the second most deadly disease and one of the most important public health concerns worldwide. Surgery, chemotherapy, radiation therapy, and immune therapy are the major types of treatment strategies that have been implemented in cancer treatment. Unfortunately, these treatment options suffer from major limitations, such as drug-resistance and adverse effects, which may eventually result in disease recurrence. Many phytochemicals have been investigated for their antitumor efficacy in preclinical models and clinical studies to discover newer therapeutic agents with fewer adverse effects. Withaferin A, a natural bioactive molecule isolated from the Indian medicinal plant Withania somnifera (L.) Dunal, has been reported to impart anticancer activities against various cancer cell lines and preclinical cancer models by modulating the expression and activity of different oncogenic proteins. In this article, we have comprehensively discussed the biosynthesis of withaferin A as well as its antineoplastic activities and mode-of-action in in vitro and in vivo settings. We have also reviewed the effect of withaferin A on the expression of miRNAs, its combinational effect with other cytotoxic agents, withaferin A-based formulations, safety and toxicity profiles, and its clinical potential.

Molecular mechanisms behind ROS regulation in cancer: A balancing act between augmented tumorigenesis and cell apoptosis

ROS include hydroxyl radicals (HO^.), superoxide (O₂^..), and hydrogen peroxide (H₂O₂). ROS are typically produced under physiological conditions and play crucial roles in living organisms. It is known that ROS, which are created spontaneously by cells through aerobic metabolism in mitochondria, can have either a beneficial or detrimental influence on biological systems. Moderate levels of ROS can cause oxidative damage to proteins, DNA and lipids, which can aid in the pathogenesis of many disorders, including cancer. However, excessive concentrations of ROS can initiate programmed cell death in cancer. Presently, a variety of chemotherapeutic drugs and herbal agents are being investigated to induce ROS-mediated cell death in cancer. Therefore, preserving ROS homeostasis is essential for ensuring normal cell development and survival. On account of a significant association of ROS levels at various concentrations with carcinogenesis in a number of malignancies, further studies are needed to determine the underlying molecular mechanisms and develop the possibilities for intervening in these processes.

A phase II study to explore biomarkers for the use of mFOLFOX6/XELOX plus bevacizumab as a first-line chemotherapy in patients with metastatic colorectal cancer (WJOG7612GTR)

BACKGROUND

The purpose of this prospective study was to assess the ability of plasma vascular endothelial growth factor-A short isoforms (pVEGF-Asi) to predict bevacizumab (BV) efficacy and to explore other circulating biomarkers in metastatic colorectal cancer (mCRC) patients treated with modified FOLFOX6/XELOX plus BV (mFOLFOX6/XELOX + BV).

PATIENTS AND METHODS

Pre-treatment plasma samples were collected from 100 mCRC patients receiving first-line chemotherapy with mFOLFOX6/XELOX + BV. The plasma levels of 11 angiogenesis-associated molecules, including pVEGF-Asi and 22 cancer-associated gene mutations in circulating tumor DNA, were analyzed. For the primary endpoint, we assumed that the hazard ratio (HR) for progression-free survival (PFS) calculated using a Cox proportional hazards model was <1.15, comparing patients with a high versus those with a low pVEGF-Asi level divided according to the median pVEGF-Asi value.

RESULTS

The median value of pVEGF-Asi was 37 (range 6.5-262) pg/ml. The HR for PFS between the high and low pVEGF-Asi patient groups was 1.3 [95% confidence interval (CI) 0.8-2.1; log rank, P = 0.25], which was larger than the predefined threshold of 1.15. The multivariate analysis demonstrated that PFS was significantly associated with plasma intercellular adhesion molecule-1 (pICAM-1) (≥190.0 versus <190.0 ng/ml; HR 2.1; 95% CI 1.3-3.5), RAS (mutant versus wild; HR 2.5; 95% CI 1.5-4.3), and FBXW7 (mutant versus wild; HR 2.8; 95% CI 1.2-6.8), whereas overall survival was significantly associated with pICAM-1 (HR 2.0; 95% CI 1.1-3.7) and RAS (HR 2.6; 95% CI 1.5-4.6).

CONCLUSIONS

The addition of BV was unable to compensate for the poor PFS associated with a high pVEGF-Asi level, suggesting that pVEGF-Asi is unlikely to be a good predictive biomarker of the efficacy of mFOLFOX6/XELOX + BV therapy. The clinical significance of circulating ICAM-1, mutant RAS, and mutant FBXW7 levels should be studied further.

Dysregulation of FBW7 in malignant lymphoproliferative disorders

The ubiquitin-proteasome system (UPS) is involved in various aspects of cell processes, including cell proliferation, differentiation, and cell cycle progression. F-box and WD repeat domain-containing protein 7 (FBW7), as a key component of UPS proteins and a critical tumor suppressor in human cancers, controls proteasome-mediated degradation by ubiquitinating oncoproteins such as c-Myc, Mcl-1, cyclin E, and Notch. It also plays a role in the development of various cancers, including solid and hematological malignancies, such as T-cell acute lymphoblastic leukemia, diffuse large B-cell lymphoma, and multiple myeloma. This comprehensive review emphasizes the functions, substrates, and expression of FBW7 in malignant lymphoproliferative disorders.

E3 ubiquitin ligase FBXW7 enhances radiosensitivity of non-small cell lung cancer cells by inhibiting SOX9 regulation of CDKN1A through ubiquitination

Non-small cell lung cancer (NSCLC) has high rates of morbidity and mortality. E3 ubiquitin ligase usually has antitumor effects. This study evaluated the mechanism of E3 ligase FBXW7 (F-box and WD repeat domain containing 7) in the radiosensitivity of NSCLC. NCI-H1299 and NCI-H1299R cells were irradiated by 0, 2, 4, and 6 Gy doses of X-ray, respectively. In addition to the measurement of cell proliferation, apoptosis, and γ-H2AX, FBXW7 expression was measured and the interaction between FBXW7 and SOX9 (SRY-box transcription factor 9) was evaluated. Ubiquitination level and protein stability of SOX9 were examined after FBXW7 overexpression. The binding relationship between SOX9 and CDKN1A (cyclin-dependent kinase inhibitor 1A) was verified. Xenograft tumor model was established to evaluate the effect of FBXW7 on radiosensitivity in vivo. FBXW7 was under-expressed in radioresistant cells. Overexpression of FBXW7 repressed NCI-H1299 and NCI-H1299R cell proliferation and colony formation and increased γ-H2AX-positive foci. Overexpression of FBXW7 increased the ubiquitination level and reduced the protein stability of SOX9. SOX9 bound to the CDKN1A promoter to inhibit CDKN1A expression. FBXW7 inhibited tumorigenesis and apoptosis and enhanced radiosensitivity of NSCLC cells in vivo via the SOX9/CDKN1A axis. Overall, FBXW7 inhibited SOX9 expression by promoting SOX9 ubiquitination and proteasome degradation, suppressing the binding of SOX9 to CDKN1A, and upregulating CDKN1A, thereby improving the radiosensitivity of NSCLC cells.

Unraveling the Potential Role of NEDD4-like E3 Ligases in Cancer

Cancer is a deadly disease worldwide, with an anticipated 19.3 million new cases and 10.0 million deaths occurring in 2020 according to GLOBOCAN 2020. It is well established that carcinogenesis and cancer development are strongly linked to genetic changes and post-translational modifications (PTMs). An important PTM process, ubiquitination, regulates every aspect of cellular activity, and the crucial enzymes in the ubiquitination process are E3 ubiquitin ligases (E3s) that affect substrate specificity and must therefore be carefully regulated. A surfeit of studies suggests that, among the E3 ubiquitin ligases, neuronal precursor cell-expressed developmentally downregulated 4 (NEDD4)/NEDD4-like E3 ligases show key functions in cellular processes by controlling subsequent protein degradation and substrate ubiquitination. In addition, it was demonstrated that NEDD4 mainly acts as an oncogene in various cancers, but also plays a tumor-suppressive role in some cancers. In this review, to comprehend the proper function of NEDD4 in cancer development, we summarize its function, both its tumor-suppressive and oncogenic role, in multiple types of malignancies. Moreover, we briefly explain the role of NEDD4 in carcinogenesis and progression, including cell survival, cell proliferation, autophagy, cell migration, invasion, metastasis, epithelial-mesenchymal transition (EMT), chemoresistance, and multiple signaling pathways. In addition, we briefly explain the significance of NEDD4 as a possible target for cancer treatment. Therefore, we conclude that targeting NEDD4 as a therapeutic method for treating human tumors could be a practical possibility.

Circular RNA circ-BNC2 (hsa_circ_0008732) inhibits the progression of ovarian cancer through microRNA-223-3p/ FBXW7 axis

Background

Circular RNAs (circRNAs) are reported to be key regulators in the progression of human cancers. This work focuses on the function and molecular mechanism of circRNA-BNC2 (circ-BNC2) (also known as hsa_circ_0008732) in ovarian cancer (OC).

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to detect circ-BNC2, microRNA-223-3p (miR-223-3p) and F-box and WD repeat domain containing 7 (FBXW7) mRNA expressions in OC tissues and cells. Besides, cell counting kit 8 (CCK-8), transwell assay and cell cycle assays were executed to assess the proliferative, migrative, invasive abilities, and cell cycle progression of OC cells, respectively. Dual-luciferase reporter gene assay and RNA pull-down assay were used to validate the targeting relationships between miR-223-3p and circ-BNC2 or FBXW7. Western blot was adopted to determine FBXW7 protein levels in OC cells.

Results

Circ-BNC2 expression was downregulated in OC tissues and cell lines, which was associated with higher FIGO stage and lymph node metastasis of OC patients. Circ-BNC2 overexpression repressed the proliferation, migration, invasion of OC cells and induced cell cycle arrest, while silencing circ-BNC2 worked oppositely. Mechanistically, circ-BNC2 could upregulate FBXW7 expression in OC cells via sponging miR-223-3p.

Conclusion

Circ-BNC2 suppresses the progression of OC via regulating miR-223-3p / FBXW7 axis. Our findings provided potential biomarker for OC therapy.

USP28 Deubiquitinates TCF7L2 to Govern the Action of Wnt Signaling Pathway in Hepatic Carcinoma

Overexpression of ubiquitin‐specific protease 28 (USP28) is found in hepatic carcinoma. It is unclear whether the deubiquitinase plays a role in hepatocarcinogenesis. Deregulation of the Wnt signaling pathway is frequently associated with liver cancer. Transcription factor 7‐like 2 (TCF7L2) is an important downstream transcription factor of the Wnt/β‐catenin signaling pathway, but the mechanisms by which TCF7L2 itself is regulated have not yet been revealed. Here, we report that USP28 promotes the activity of the Wnt signaling pathway through maintaining the stability of TCF7L2. We further show that FBXW7 is the E3 ubiquitin ligase for TCF7L2. By regulating the levels of TCF7L2, USP28 modulates the Wnt/β‐catenin signaling in liver cancer and USP28 depletion or inhibition by a small molecule inhibitor leads to a halt of growth in liver cancer cells. These results suggest that USP28 could be a potential therapeutic target for liver cancer.

Molecular Characterization of the Response to Conventional Chemotherapeutics in Pro-B-ALL Cell Lines in Terms of Tumor Relapse

Little is known about optimally applying chemotherapeutic agents in a specific temporal sequence to rapidly reduce the tumor load and to improve therapeutic efficacy. The clinical optimization of drug efficacy while reducing side effects is still restricted due to an incomplete understanding of the mode of action and related tumor relapse mechanisms on the molecular level. The molecular characterization of transcriptomic drug signatures can help to identify the affected pathways, downstream regulated genes and regulatory interactions related to tumor relapse in response to drug application. We tried to outline the dynamic regulatory reprogramming leading to tumor relapse in relapsed MLL-rearranged pro-B-cell acute lymphoblastic leukemia (B-ALL) cells in response to two first-line treatments: dexamethasone (Dexa) and cytarabine (AraC). We performed an integrative molecular analysis of whole transcriptome profiles of each treatment, specifically considering public knowledge of miRNA regulation via a network-based approach to unravel key driver genes and miRNAs that may control the relapse mechanisms accompanying each treatment. Our results gave hints to the crucial regulatory roles of genes leading to Dexa-resistance and related miRNAs linked to chemosensitivity. These genes and miRNAs should be further investigated in preclinical models to obtain more hints about relapse processes.

Induction of GLI1 by miR-27b-3p/FBXW7/KLF5 pathway contributes to pulmonary arterial hypertension

Glioma-associated oncogene homolog 1 (GLI1), a zinc-finger transcription factor, is upregulated in tumors and promotes cancer cell proliferation and migration. However, whether GLI1 involves in pulmonary artery smooth muscle cells (PASMCs) proliferation and migration and the detailed molecular mechanisms underlying GLI1 in pulmonary arterial hypertension (PAH) are not yet clear. Primary cultured rat PASMCs and monocrotaline (MCT)-induced PAH rats model were applied to address these issues in the present study. We found that the expression of GLI1 was significantly increased in endothelin-1 (ET-1) treated PASMCs, accompanied with the activation of microRNA (miR)-27b-3p/F-box and WD repeat domain containing 7 (FBXW7)/kruppel-like factor 5 (KLF5)/GLI1 pathway through endothelin-1 receptor type A (ETAR). Elevated miR-27b-3p suppressed FBXW7 expression, which led to KLF5 accumulation by decreasing its ubiquitinated degradation, KLF5 further induced GLI1 upregulation leading to PASMCs proliferation and migration. In addition, in MCT-induced PAH rats, targeting ETAR/miR-27b-3p/FBXW7/KLF5/GLI1 pathway effectively prevented the pulmonary vascular remodeling and the development of PAH in rats. Our study indicates that interfering ETAR/miR-27b-3p/FBXW7/KLF5/GLI1 signaling axis might have a potential value in the prevention and treatment of PAH.

FBXO9 Mediates the Cancer-Promoting Effects of ZNF143 by Degrading FBXW7 and Facilitates Drug Resistance in Hepatocellular Carcinoma

F-box proteins are critical for malignancy because they control the turnover of key proteins that govern multiple cellular processes. F-box protein 9 (FBXO9) belongs to the F-box protein family and exhibits oncogenic properties in hematological malignancies. However, the function and molecular mechanism of FBXO9 in hepatocellular carcinoma (HCC) remain unclear. Here, we report that FBXO9 was remarkably overexpressed in HCC. Loss- and gain-of-function experiments showed that FBXO9 facilitates HCC cell proliferation and metastasis both in vitro and in vivo. Mechanistically, as a direct upstream transcription factor, FBXO9 is regulated by zinc finger protein 143 (ZNF143) and accelerates tumor growth and metastasis by targeting the F-box and WD repeat domain containing 7 (FBXW7) for ubiquitination and degradation. Additionally, we found that with FBXO9 knockdown, HCC cells were more sensitive to treatment with lenvatinib and sorafenib. In summary, our results demonstrate that a ZNF143-FBXO9-FBXW7 signaling regulatory axis may be involved in tumor progression in HCC, and suggest that FBXO9 could be a potential biomarker and therapeutic target for HCC.

Genomic Aberrations in Circulating Tumor DNAs from Palbociclib-Treated Metastatic Breast Cancer Patients Reveal a Novel Resistance Mechanism

Previously undescribed molecular mechanisms of resistance will emerge with the increased use of cyclin-dependent kinase 4/6 inhibitors in clinical settings. To identify genomic aberrations in circulating tumor DNA associated with treatment resistance in palbociclib-treated metastatic breast cancer (MBC) patients, we collected 35 pre- and post-treatment blood samples from 16 patients with estrogen receptor-positive (ER⁺) MBC, including 9 with inflammatory breast cancer (IBC). Circulating cell-free DNAs (cfDNAs) were isolated for sequencing using a targeted panel of 91 genes. Our data showed that FBXW7 and CDK6 were more frequently altered in IBC than in non-IBC, whereas conversely, PIK3CA was more frequently altered in non-IBC than in IBC. The cfDNA samples collected at follow-up harbored more mutations than baseline samples. By analyzing paired samples, we observed a higher percentage of patients with mutations in RB1, CCNE1, FBXW7, EZH2, and ARID1A, but a lower proportion of patients with mutated TSC2 at the post-treatment stage when they developed progression. Moreover, acquisition of CCNE1 mutations or loss of TSC2 mutations after treatment initiation conferred an unfavorable prognosis. These data provide insights into the relevance of novel genomic alterations in cfDNA to palbociclib resistance in MBC patients. Future large-scale prospective studies are warranted to confirm our findings.

Modified Adenosines Sensitize Glioblastoma Cells to Temozolomide by Affecting DNA Methyltransferases

Glioblastoma (GBM) is the most common and lethal primary malignant brain tumor, and due to its unique features, its management is certainly one of the most challenging ones among all cancers. N6-isopentenyladenosine (IPA) and its analog N6-benzyladenosine (N6-BA) are modified nucleosides endowed with potent antitumor activity on different types of human cancers, including GBM. Corroborating our previous finding, we demonstrated that IPA and N6-BA affect GBM cell line proliferation by modulating the expression of the F-box WD repeat domain-containing-7 (FBXW7), a tumor suppressor with a crucial role in the turnover of many proteins, such as SREBPs and Mcl1, involved in malignant progression and chemoresistance. Luciferase assay revealed that IPA-mediated upregulation of FBXW7 translates in transcriptional inactivation of its oncogenic substrates (Myc, NFkB, or HIF-1α). Moreover, downregulating MGMT expression, IPA strongly enhances the killing effect of temozolomide (TMZ), producing a favorable sensitizing effect starting from a concentration range much lower than TMZ EC50. Through DNA methyltransferase (DNMT) activity assay, analysis of the global DNA methylation, and the histone modification profiles, we demonstrated that the modified adenosines behave similar to 5-AZA-dC, known DNMT inhibitor. Overall, our results provide new perspectives for the first time, suggesting the modified adenosines as epigenetic tools able to improve chemo- and radiotherapy efficacy in glioblastoma and potentially other cancers.

Noncoding RNAs and their therapeutics in paclitaxel chemotherapy: Mechanisms of initiation, progression, and drug sensitivity

The identification of agents that can reverse drug resistance in cancer chemotherapy, and enhance the overall efficacy is of great interest. Paclitaxel (PTX) belongs to taxane family that exerts an antitumor effect by stabilizing microtubules and inhibiting cell cycle progression. However, PTX resistance often develops in tumors due to the overexpression of drug transporters and tumor-promoting pathways. Noncoding RNAs (ncRNAs) are modulators of many processes in cancer cells, such as apoptosis, migration, differentiation, and angiogenesis. In the present study, we summarize the effects of ncRNAs on PTX chemotherapy. MicroRNAs (miRNAs) can have opposite effects on PTX resistance (stimulation or inhibition) via influencing YES1, SK2, MRP1, and STAT3. Moreover, miRNAs modulate the growth and migration rates of tumor cells in regulating PTX efficacy. PIWI-interacting RNAs, small interfering RNAs, and short-hairpin RNAs are other members of ncRNAs regulating PTX sensitivity of cancer cells. Long noncoding RNAs (LncRNAs) are similar to miRNAs and can modulate PTX resistance/sensitivity by their influence on miRNAs and drug efflux transport. The cytotoxicity of PTX against tumor cells can also be affected by circular RNAs (circRNAs) and limitation is that oncogenic circRNAs have been emphasized and experiments should also focus on onco-suppressor circRNAs.

Non-coding RNAs and macrophage interaction in tumor progression

The macrophages are abundantly found in TME and their M2 polarization is in favor of tumor malignancy. On the other hand, non-coding RNAs (ncRNAs) can modulate macrophage polarization in TME to affect cancer progression. The miRNAs can dually induce/suppress M2 polarization of macrophages and by affecting various molecular pathways, they modulate tumor progression and therapy response. The lncRNAs can affect miRNAs via sponging and other molecular pathways to modulate macrophage polarization. A few experiments have also examined role of circRNAs in targeting signaling networks and affecting macrophages. The therapeutic targeting of these ncRNAs can mediate TME remodeling and affect macrophage polarization. Furthermore, exosomal ncRNAs derived from tumor cells or macrophages can modulate polarization and TME remodeling. Suppressing biogenesis and secretion of exosomes can inhibit ncRNA-mediated M2 polarization of macrophages and prevent tumor progression. The ncRNAs, especially exosomal ncRNAs can be considered as non-invasive biomarkers for tumor diagnosis.

Germline variants in tumor suppressor FBXW7 lead to impaired ubiquitination and a neurodevelopmental syndrome

Neurodevelopmental disorders are highly heterogenous conditions resulting from abnormalities of brain architecture and/or function. FBXW7 (F-box and WD-repeat-domain-containing 7), a recognized developmental regulator and tumor suppressor, has been shown to regulate cell-cycle progression and cell growth and survival by targeting substrates including CYCLIN E1/2 and NOTCH for degradation via the ubiquitin proteasome system. We used a genotype-first approach and global data-sharing platforms to identify 35 individuals harboring de novo and inherited FBXW7 germline monoallelic chromosomal deletions and nonsense, frameshift, splice-site, and missense variants associated with a neurodevelopmental syndrome. The FBXW7 neurodevelopmental syndrome is distinguished by global developmental delay, borderline to severe intellectual disability, hypotonia, and gastrointestinal issues. Brain imaging detailed variable underlying structural abnormalities affecting the cerebellum, corpus collosum, and white matter. A crystal-structure model of FBXW7 predicted that missense variants were clustered at the substrate-binding surface of the WD40 domain and that these might reduce FBXW7 substrate binding affinity. Expression of recombinant FBXW7 missense variants in cultured cells demonstrated impaired CYCLIN E1 and CYCLIN E2 turnover. Pan-neuronal knockdown of the Drosophila ortholog, archipelago, impaired learning and neuronal function. Collectively, the data presented herein provide compelling evidence of an F-Box protein-related, phenotypically variable neurodevelopmental disorder associated with monoallelic variants in FBXW7.

NEDD4L suppresses PD-L1 expression and enhances anti-tumor immune response in A549 cells

BACKGROUND

Non-small cell lung cancer (NSCLC) poses a salient threat to public health. E3 ubiquitin ligase commonly functions as an anti-tumor role.

OBJECTIVE

This study probed the effect of E3 ligase NEDD4L on A549 cells.

METHODS

NEDD4L expression in NSCLC and its correlation with NSCLC patient's prognosis were predicted and verified. PD-L1 protein level was measured, and the correlation between NEDD4L and PD-L1 was analyzed. The effects of NEDD4L overexpression on the binding of NEDD4L to PD-L1 and ubiquitination level of PD-L1 were examined. Xenograft tumor model was established in mice. The volume and weight of xenograft tumors were recorded. The proportion of CD8⁺ T cells and contents of IL-2 and INF-γ were detected.

RESULTS

NEDD4L expression was downregulated in NSCLC tissues and A549 cells, and correlated with poor prognosis of NSCLC patients. PD-L1 was upregulated in NSCLC and negatively correlated with NEDD4L. Overexpression of NEDD4L upregulated ubiquitination level of PD-L1 and reduced protein level of PD-L1. Overexpression of NEDD4L decreased tumor volume and weight and enhanced proportion of CD8⁺ T cells and contents of IL-2 and INF-γ.

CONCLUSIONS

Collectively, overexpression of NEDD4L suppressed PD-L1 protein level through ubiquitination, thereby enhancing anti-tumor immune response and retarding NSCLC progression.

Role of Induced Programmed Cell Death in the Chemopreventive Potential of Apigenin

The flavonoid apigenin (4′,5,7-trihydroxyflavone), which is one of the most widely distributed phytochemicals in the plant kingdom, is one of the most thoroughly investigated phenolic components. Previous studies have attributed the physiological effects of apigenin to its anti-allergic, antibacterial, antidiabetic, anti-inflammatory, antioxidant, antiviral, and blood-pressure-lowering properties, and its documented anticancer properties have been attributed to the induction of apoptosis and autophagy, the inhibition of inflammation, angiogenesis, and cell proliferation, and the regulation of cellular responses to oxidative stress and DNA damage. The most well-known mechanism for the compound’s anticancer effects in human cancer cell lines is apoptosis, followed by autophagy, and studies have also reported that apigenin induces novel cell death mechanisms, such as necroptosis and ferroptosis. Therefore, the aim of this paper is to review the therapeutic potential of apigenin as a chemopreventive agent, as well as the roles of programmed cell death mechanisms in the compound’s chemopreventive properties.

Targeting autophagy in prostate cancer: preclinical and clinical evidence for therapeutic response

Prostate cancer is a leading cause of death worldwide and new estimates revealed prostate cancer as the leading cause of death in men in 2021. Therefore, new strategies are pertinent in the treatment of this malignant disease. Macroautophagy/autophagy is a “self-degradation” mechanism capable of facilitating the turnover of long-lived and toxic macromolecules and organelles. Recently, attention has been drawn towards the role of autophagy in cancer and how its modulation provides effective cancer therapy. In the present review, we provide a mechanistic discussion of autophagy in prostate cancer. Autophagy can promote/inhibit proliferation and survival of prostate cancer cells. Besides, metastasis of prostate cancer cells is affected (via induction and inhibition) by autophagy. Autophagy can affect the response of prostate cancer cells to therapy such as chemotherapy and radiotherapy, given the close association between autophagy and apoptosis. Increasing evidence has demonstrated that upstream mediators such as AMPK, non-coding RNAs, KLF5, MTOR and others regulate autophagy in prostate cancer. Anti-tumor compounds, for instance phytochemicals, dually inhibit or induce autophagy in prostate cancer therapy. For improving prostate cancer therapy, nanotherapeutics such as chitosan nanoparticles have been developed. With respect to the context-dependent role of autophagy in prostate cancer, genetic tools such as siRNA and CRISPR-Cas9 can be utilized for targeting autophagic genes. Finally, these findings can be translated into preclinical and clinical studies to improve survival and prognosis of prostate cancer patients.

• Prostate cancer is among the leading causes of death in men where targeting autophagy is of importance in treatment;

• Autophagy governs proliferation and metastasis capacity of prostate cancer cells;

• Autophagy modulation is of interest in improving the therapeutic response of prostate cancer cells;

• Molecular pathways, especially involving non-coding RNAs, regulate autophagy in prostate cancer;

• Autophagy possesses both diagnostic and prognostic roles in prostate cancer, with promises for clinical application.

Myeloid Fbxw7 Prevents Pulmonary Fibrosis by Suppressing TGF-β Production

Idiopathic pulmonary fibrosis (IPF) is a group of chronic interstitial pulmonary diseases characterized by an inexorable decline in lung function with limited treatment options. The abnormal expression of transforming growth factor-β (TGF-β) in profibrotic macrophages is linked to severe pulmonary fibrosis, but the regulation mechanisms of TGF-β expression are incompletely understood. We found that decreased expression of E3 ubiquitin ligase Fbxw7 in peripheral blood mononuclear cells (PBMCs) was significantly related to the severity of pulmonary fibrosis in IPF patients. Fbxw7 is identified to be a crucial suppressing factor for pulmonary fibrosis development and progression in a mouse model induced by intratracheal bleomycin treatment. Myeloid cell-specific Fbxw7 deletion increases pulmonary monocyte-macrophages accumulation in lung tissue, and eventually promotes bleomycin-induced collagen deposition and progressive pulmonary fibrosis. Notably, the expression of TGF-β in profibrotic macrophages was significantly upregulated in myeloid cell-specific Fbxw7 deletion mice after bleomycin treatment. C-Jun has long been regarded as a critical transcription factor of Tgfb1, we clarified that Fbxw7 inhibits the expression of TGF-β in profibrotic macrophages by interacting with c-Jun and mediating its K48-linked ubiquitination and degradation. These findings provide insight into the role of Fbxw7 in the regulation of macrophages during the pathogenesis of pulmonary fibrosis.

Transforming growth factor-beta (TGF-β) in prostate cancer: A dual function mediator?

Transforming growth factor-beta (TGF-β) is a member of a family of secreted cytokines with vital biological functions in cells. The abnormal expression of TGF-β signaling is a common finding in pathological conditions, particularly cancer. Prostate cancer (PCa) is one of the leading causes of death among men. Several genetic and epigenetic alterations can result in PCa development, and govern its progression. The present review attempts to shed some light on the role of TGF-β signaling in PCa. TGF-β signaling can either stimulate or inhibit proliferation and viability of PCa cells, depending on the context. The metastasis of PCa cells is increased by TGF-β signaling via induction of EMT and MMPs. Furthermore, TGF-β signaling can induce drug resistance of PCa cells, and can lead to immune evasion via reducing the anti-tumor activity of cytotoxic T cells and stimulating regulatory T cells. Upstream mediators such as microRNAs and lncRNAs, can regulate TGF-β signaling in PCa. Furthermore, some pharmacological compounds such as thymoquinone and valproic acid can suppress TGF-β signaling for PCa therapy. TGF-β over-expression is associated with poor prognosis in PCa patients. Furthermore, TGF-β up-regulation before prostatectomy is associated with recurrence of PCa. Overall, current review discusses role of TGF-β signaling in proliferation, metastasis and therapy response of PCa cells and in order to improve knowledge towards its regulation, upstream mediators of TGF-β such as non-coding RNAs are described. Finally, TGF-β regulation and its clinical application are discussed.

Doxorubicin-loaded graphene oxide nanocomposites in cancer medicine: Stimuli-responsive carriers, co-delivery and suppressing resistance

INTRODUCTION

The application of doxorubicin (DOX) in cancer therapy has been limited due to its drug resistance and poor internalization. Graphene oxide (GO) nanostructures have the capacity for DOX delivery while promoting its cytotoxicity in cancer.

AREAS COVERED

The favorable characteristics of GO nanocomposites, preparation method, and application in cancer therapy are described. Then, DOX resistance in cancer is discussed. The GO-mediated photothermal therapy and DOX delivery for cancer suppression are described. Preparation of stimuli-responsive GO nanocomposites, surface functionalization, hybrid nanoparticles, and theranostic applications are emphasized in DOX chemotherapy.

EXPERT OPINION

Graphene oxide nanoparticle-based photothermal therapy maximizes the anti-cancer activity of DOX against cancer cells. Apart from DOX delivery, GO nanomaterials are capable of loading anti-cancer agents and genetic tools to minimize drug resistance and enhance the cytolytic impact of DOX in cancer eradication. To enhance DOX accumulation in cancer cells, stimuli-responsive (redox-, light-, enzyme- and pH-sensitive) GO nanoparticles have been developed for DOX delivery. Further development of targeted delivery of DOX-loaded GO nanomaterials against cancer cells may be achieved by surface modification of polymers such as polyethylene glycol, hyaluronic acid, and chitosan. Doxorubicin-loaded GO nanoparticles have demonstrated theranostic potential for simultaneous diagnosis and therapy. Hybridization of GO with other nanocarriers such as silica and gold nanoparticles further broadens their potential anti-cancer therapy applications.

MiR-182-5p inhibits the tumorigenesis of clear cell renal cell carcinoma by repressing UBE2T

Ubiquitin-conjugating enzyme E2T (UBE2T), a member of the E2 family, has been reported to be overexpressed in certain tumor types and to have an important role in the Fanconi anemia pathway. However, the role of UBE2T in clear cell renal cell carcinoma (ccRCC) has not been clarified. MicroRNAs (miRNAs) participate in tumorigenesis by binding to genes and proteins that regulate cell proliferation or cell apoptosis. The aim of this study was to determine the role of UBE2T and the relationship between miR-182-5p and UBE2T in ccRCC. In the present study, UBE2T expression levels in ccRCC tissues and cells were assessed using real-time quantitative PCR (RT-qPCR) and western blotting. UBE2T protein expression was assessed in a total of 93 ccRCC patients from Peking University First Hospital (PKU) via immunohistochemistry (IHC). The effects of UBE2T knockdown on ccRCC cells were assessed with MTS assays, wound healing assays, Transwell invasion assays and flow cytometry. The effects of in vivo treatment were evaluated through xenograft experiments. The relationship between miR-182-5p and UBE2T was verified with a dual-luciferase reporter gene assay. We found that UBE2T was highly expressed in ccRCC cells and tissues. High UBE2T expression was positively correlated with advanced pathological stage, histological grade, maximum tumor diameter and distant metastasis. Multivariate analysis revealed that UBE2T expression was an independent risk factor for overall survival (OS) and recurrence-free survival (RFS) in patients with ccRCC. Knockdown of UBE2T significantly suppressed RCC cell proliferation, migration and invasion. Flow cytometry analysis showed that UBE2T knockdown promoted RCC cell cycle arrest at G2/M phase and increased cell apoptosis. The xenograft model confirmed that suppression of UBE2T significantly delayed tumor formation and growth in vivo. In addition, miR-182-5p inhibited UBE2T protein expression by targeting UBE2T mRNA and then inhibited the proliferation, migration and invasion of ccRCC cell. Our research reveals that UBE2T likely plays a critical role in ccRCC progression and may be a potential therapeutic target for ccRCC.

Loss of FBXW7 Correlates with Increased IDH1 Expression in Glioma and Enhances IDH1-Mutant Cancer Cell Sensitivity to Radiation

F-box and WD repeat domain containing 7 (FBXW7) is a substrate receptor of the ubiquitin ligase SKP1-Cullin1-F-box complex and a potent tumor suppressor that prevents unregulated cell growth and tumorigenesis. However, little is known about FBXW7-mediated control of cell metabolism and related functions in cancer therapy. Here, we report that FBXW7 expression inversely correlates with the expression levels of the key metabolic enzyme isocitrate dehydrogenase 1 (IDH1) in patients with glioma and public glioma datasets. Deletion of FBXW7 significantly increased both wild-type (WT) and mutant IDH1 expression, which was mediated by blocking degradation of sterol regulatory element binding protein 1 (SREBP1). The upregulation of neomorphic mutant IDH1 by FBXW7 deletion stimulated production of the oncometabolite 2-hydroxyglutarate at the expense of increasing pentose phosphate pathway activity and NADPH consumption, limiting the buffering ability against radiation-induced oxidative stress. In addition, FBXW7 knockout and IDH1 mutations induced nonhomologous end joining and homologous recombination defects, respectively. In vitro and in vivo, loss of FBXW7 dramatically enhanced the efficacy of radiation treatment in IDH1-mutant cancer cells. Taken together, this work identifies FBXW7 deficiency as a potential biomarker representing both DNA repair and metabolic vulnerabilities that sensitizes IDH1-mutant cancers to radiotherapy. SIGNIFICANCE: Deficiency of FBXW7 causes defects in DNA repair and disrupts NADPH homeostasis in IDH1-mutant glioma cells, conferring high sensitivity to radiotherapy.

Ubiquitination of NF-κB p65 by FBXW2 suppresses breast cancer stemness, tumorigenesis, and paclitaxel resistance

The F-box and WD-repeat-containing protein 2 (FBXW2) plays a crucial role as an E3 ligase in regulating tumorigenesis. However, the functions of FBXW2 in breast cancer are still unknown. Here, we find that nuclear factor-kB (NF-κB) p65 is a new substrate of FBXW2. FBXW2 directly binds to p65, leading to its ubiquitination and degradation. Interestingly, p300 acetylation of p65 blocks FBXW2 induced p65 ubiquitination. FBXW2-p65 axis is a crucial regulator of SOX2-induced stemness in breast cancer. Moreover, FBXW2 inhibits breast tumor growth by regulating p65 degradation in vitro and in vivo. FBXW2 overexpression abrogates the effects of p65 on paclitaxel resistance in vitro and in vivo. Furthermore, FBXW2 induced p65 degradation is also confirmed in FBXW2-knockout mice. Our results identify FBXW2 as an important E3 ligase for p65 degradation, which provide insights into the tumor suppressor functions of FBXW2 in breast cancer.

Targeting Oncogenic Pathways in the Era of Personalized Oncology: A Systemic Analysis Reveals Highly Mutated Signaling Pathways in Cancer Patients and Potential Therapeutic Targets

Cancer is the second leading cause of death globally. One of the main hallmarks in cancer is the functional deregulation of crucial molecular pathways via driver genetic events that lead to abnormal gene expression, giving cells a selective growth advantage. Driver events are defined as mutations, fusions and copy number alterations that are causally implicated in oncogenesis. Molecular analysis on tissues that have originated from a wide range of anatomical areas has shown that mutations in different members of several pathways are implicated in different cancer types. In recent decades, significant efforts have been made to incorporate this knowledge into daily medical practice, providing substantial insight towards clinical diagnosis and personalized therapies. However, since there is still a strong need for more effective drug development, a deep understanding of the involved signaling mechanisms and the interconnections between these pathways is highly anticipated. Here, we perform a systemic analysis on cancer patients included in the Pan-Cancer Atlas project, with the aim to select the ten most highly mutated signaling pathways (p53, RTK-RAS, lipids metabolism, PI-3-Kinase/Akt, ubiquitination, b-catenin/Wnt, Notch, cell cycle, homology directed repair (HDR) and splicing) and to provide a detailed description of each pathway, along with the corresponding therapeutic applications currently being developed or applied. The ultimate scope is to review the current knowledge on highly mutated pathways and to address the attractive perspectives arising from ongoing experimental studies for the clinical implementation of personalized medicine.

Autophagy Regulates VDAC3 Ubiquitination by FBXW7 to Promote Erastin-Induced Ferroptosis in Acute Lymphoblastic Leukemia

Background: The discovery of ferroptosis is a major breakthrough in the development of cancer treatments. However, the mechanism by which ferroptosis contributes to acute lymphoblastic leukemia (ALL) is to be clarified. Here, we explored erastin-induced ferroptosis in ALL cells and the impact of autophagic activity on this process.

Materials and Methods: Cell viability was evaluated in various ALL cell lines following erastin treatment by the MTS assay, while cell death was evaluated via a trypan blue assay. Immunoblotting and quantitative real-time PCR were used to detect protein and mRNA expression, respectively. The UbiBrowser database was used to predict the E3 ligase of VDAC3, which was confirmed by immunoprecipitation. The role of FBXW7 in erastin-induced ferroptosis in vitro was evaluated via lentiviral-mediated silencing and overexpression. ALL xenograft mice were used to observe the impact of autophagy on erastin-induced ferroptosis.

Results: Resistance to erastin-induced ferroptosis was higher in Jurkat and CCRF-CEM cells than in Reh cells. The sensitivity could be modified by the autophagy activator rapamycin (Rapa) and the autophagy inhibitor chloroquine (CQ). Rapa sensitized ALL cells to erastin-induced ferroptosis. In ALL xenograft mice, the combination treatment of Rapa and erastin resulted in longer survival time than those observed with erastin or Rapa treatment alone. VDAC3 was regulated by autophagy post-transcriptionally, mainly via the ubiquitin-proteasome system (UPS). FBXW7 was verified as a specific E3 ligase of VDAC3. FBXW7 knockdown attenuated VDAC3 degradation by suppressing its ubiquitination, thereby increasing the sensitivity of ALL cells to erastin.

Conclusion: Autophagy regulated erastin-induced ferroptosis via the FBXW7-VDAC3 axis. Rapa sensitized ALL cells to erastin-induced ferroptosis both in vitro and in vivo. Our findings provide potential therapeutic targets for ALL.