Role of WWOX and NF-κB in lung cancer progression

Diverse roles of UBE2S in cancer and therapy resistance: Biological functions and mechanisms

The Ubiquitin Conjugating Enzyme E2 S (UBE2S), was initially identified as a crucial member in controlling substrate ubiquitination during the late promotion of the complex's function. In recent years, UBE2S has emerged as a significant epigenetic modification in various diseases, including myocardial ischemia, viral hepatitis, and notably, cancer. Mounting evidence suggests that UBE2S plays a pivotal role in several human malignancies including breast cancer, lung cancer, hepatocellular carcinoma and etc. However, a comprehensive review of UBE2S in human tumor research remains absent. Therefore, this paper aims to fill this gap. This review provides a comprehensive analysis of the structural characteristics of UBE2S and its potential utility as a biomarker in diverse cancer types. Additionally, the role of UBE2S in conferring resistance to tumor treatment is examined. The findings suggest that UBE2S holds promise as a diagnostic and therapeutic target in multiple malignancies, thereby offering novel avenues for cancer therapy.

WWOX Modulates ROS-Dependent Senescence in Bladder Cancer

The tumor-suppressor gene, WW domain-containing oxidoreductase (WWOX), has been found to be lost in various types of cancers. ROS result as a tightly regulated signaling process for the induction of cell senescence. The aim of this study was to investigate the role of WWOX in the regulation of ROS and cell senescence, which is intriguing in terms of the possible mechanism of WWOX contributing to bladder cancer. In this study, we used the AY-27 rat bladder tumor cell line and F344 orthotopic bladder tumor models to reveal the pro-senescence effects of WWOX and the corresponding underlying mechanism in bladder cancer. WWOX-overexpressing lentivirus (LV-WWOX) remarkably stimulated cellular senescence, including increased senescence-associated secretory phenotype (SASP) formation, enlarged cellular morphology, and induced SA-β-Gal-positive staining. A further mechanism study revealed that the pro-senescence effect of LV-WWOX was dependent on increased intercellular reactive oxygen species (ROS) generation, which subsequently triggered p21/p27. Moreover, LV-WWOX significantly inhibited the tumor size by 30.49% in the F344/AY-27 rat orthotopic model (p < 0.05) by activating cellular senescence. The expression of p21 was significantly enhanced in the orthotopic bladder tumors under WWOX treatment. The orthotopic bladder tumors in the groups of rats verified the effect in vivo. Our study suggests that WWOX, an ROS-dependent senescence-induced gene, could be further studied for its therapeutic implications in bladder cancer.

Photoreceptor Cell Calcium Dysregulation and Calpain Activation Promote Pathogenic Photoreceptor Oxidative Stress and Inflammation in Prodromal Diabetic Retinopathy

This study tested the hypothesis that diabetes promotes a greater than normal cytosolic calcium level in rod cells that activates a Ca2+-sensitive protease, calpain, resulting in oxidative stress and inflammation, two pathogenic factors of early diabetic retinopathy. Nondiabetic and 2-month diabetic C57Bl/6J and calpain1 knockout (Capn1-/-) mice were studied; subgroups were treated with a calpain inhibitor (CI). Ca2+ content was measured in photoreceptors using Fura-2. Retinal calpain expression was studied by quantitative RT-PCR and immunohistochemistry. Superoxide and expression of inflammatory proteins were measured using published methods. Proteomic analysis was conducted on photoreceptors isolated from untreated diabetic mice or treated daily with CI for 2 months. Cytosolic Ca2+ content was increased twofold in photoreceptors of diabetic mice as compared with nondiabetic mice. Capn1 expression increased fivefold in photoreceptor outer segments of diabetic mice. Pharmacologic inhibition or genetic deletion of Capn1 significantly suppressed diabetes-induced oxidative stress and expression of proinflammatory proteins in retina. Proteomics identified a protein (WW domain-containing oxidoreductase [WWOX]) whose expression was significantly increased in photoreceptors from mice diabetic for 2 months and was inhibited with CI. Knockdown of Wwox using specific siRNA in vitro inhibited increase in superoxide caused by the high glucose. These results suggest that reducing Ca2+ accumulation, suppressing calpain activation, and/or reducing Wwox up-regulation are novel targets for treating early diabetic retinopathy.

PLEK2, RRM2, GCSH: A Novel WWOX-Dependent Biomarker Triad of Glioblastoma at the Crossroads of Cytoskeleton Reorganization and Metabolism Alterations

Glioblastoma is one of the deadliest human cancers. Its malignancy depends on cytoskeleton reorganization, which is related to, e.g., epithelial-to-mesenchymal transition and metastasis. The malignant phenotype of glioblastoma is also affected by the WWOX gene, which is lost in nearly a quarter of gliomas. Although the role of WWOX in the cytoskeleton rearrangement has been found in neural progenitor cells, its function as a modulator of cytoskeleton in gliomas was not investigated. Therefore, this study aimed to investigate the role of WWOX and its collaborators in cytoskeleton dynamics of glioblastoma. Methodology on RNA-seq data integrated the use of databases, bioinformatics tools, web-based platforms, and machine learning algorithm, and the obtained results were validated through microarray data. PLEK2, RRM2, and GCSH were the most relevant WWOX-dependent genes that could serve as novel biomarkers. Other genes important in the context of cytoskeleton (BMP4, CCL11, CUX2, DUSP7, FAM92B, GRIN2B, HOXA1, HOXA10, KIF20A, NF2, SPOCK1, TTR, UHRF1, and WT1), metabolism (MTHFD2), or correlation with WWOX (COL3A1, KIF20A, RNF141, and RXRG) were also discovered. For the first time, we propose that changes in WWOX expression dictate a myriad of alterations that affect both glioblastoma cytoskeleton and metabolism, rendering new therapeutic possibilities.

The WWOX gene in brain development and pathology

Shortly after its discovery in 2000, WWOX was hailed as a tumor suppressor gene. In subsequent years of research, this function was confirmed indisputably. Majority of tumors show high rate of loss of heterozygosity and decreased expression of WWOX. Nevertheless, over the years, the range of its known functions, at the cellular, organ and system levels, has expanded to include metabolism and endocrine system control and CNS differentiation and functioning. Despite of its function as a tumor suppressor gene, WWOX genetic alternations were found in a number of metabolic and neural diseases. A lack of WWOX protein as a consequence of germline mutations results in brain development disturbances and malfunctions.

CaSR Induces Osteoclast Differentiation and Promotes Bone Metastasis in Lung Adenocarcinoma

Objective: Explore the mechanism of CaSR's involvement in bone metastasis in lung adenocarcinoma.

Methods: Immunohistochemistry (IHC) was used to detect the expression of calcium-sensing receptor (CaSR) in 120 cases of lung adenocarcinoma with bone metastasis. Stably transfected cell lines with CaSR overexpression and knockdown based on A549 cells were constructed. The expression of CaSR was verified by western blot and qPCR. The proliferation and migration abilities of A549 cells were tested using cholecystokinin-8 (CCK-8) and Transwell assays, respectively. Western blotting was used to detect the expression of matrix metalloproteinases MMP2, MMP9, CaSR, and NF-κB. The supernatant from each cell culture group was collected as a conditional co-culture solution to study the induction of osteoclast precursor cells and osteoblasts. Western blot and qPCR were used to validate the expression of bone matrix degradation-related enzymes cathepsin K and hormone calcitonin receptor (CTR) and osteoblast-induced osteoclast maturation and differentiation enzyme receptor activator of nuclear factor-κB ligand (RANKL), macrophage colony-stimulating factor (M-CSF), osteoprotegerin (OPG), and PTHrP. Immunofluorescent staining was used to detect F-actin ring formation and osteocalcin expression. Western blot results for NF-κB expression identified a regulatory relationship between NF-κB and CaSR.

Results: CaSR expression in lung cancer tissues was significantly higher than that in adjacent and normal lung tissues. The expression of CaSR in lung cancer tissues with bone metastasis was higher than that in non-metastatic lung cancer tissues. The proliferation and migration ability of A549 cells increased significantly with overexpressed CaSR. The co-culture solution directly induced osteoclast precursor cells and the expression of bone matrix degradation-related enzymes significantly increased. Osteoblasts were significantly inhibited and osteoblast-induced osteoclast maturation and differentiation enzymes were significantly downregulated. It was found that the expression of NF-κB and PTHrP increased when CaSR was overexpressed. Osteoclast differentiation factor expression was also significantly increased, which directly induces osteoclast differentiation and maturation. These results were reversed when CaSR was knocked down.

Conclusions: CaSR can positively regulate NF-κB and PTHrP expression in A549 cells with a high metastatic potential, thereby promoting osteoclast differentiation and maturation, and facilitating the occurrence and development of bone metastasis in lung adenocarcinoma.

Viruses go modular

The WW domain is a modular protein structure that recognizes the proline-rich Pro-Pro-x-Tyr (PPxY) motif contained in specific target proteins. The compact modular nature of the WW domain makes it ideal for mediating interactions between proteins in complex networks and signaling pathways of the cell (e.g. the Hippo pathway). As a result, WW domains play key roles in a plethora of both normal and disease processes. Intriguingly, RNA and DNA viruses have evolved strategies to hijack cellular WW domain-containing proteins and thereby exploit the modular functions of these host proteins for various steps of the virus life cycle, including entry, replication, and egress. In this review, we summarize key findings in this rapidly expanding field, in which new virus-host interactions continue to be identified. Further unraveling of the molecular aspects of these crucial virus-host interactions will continue to enhance our fundamental understanding of the biology and pathogenesis of these viruses. We anticipate that additional insights into these interactions will help support strategies to develop a new class of small-molecule inhibitors of viral PPxY-host WW-domain interactions that could be used as antiviral therapeutics.

The WWOX Gene Influences Cellular Pathways in the Neuronal Differentiation of Human Neural Progenitor Cells

The brain is the most functionally organized structure of all organs. It manages behavior, perception and higher cognitive functions. The WWOX gene is non-classical tumor suppressor gene, which has been shown to have an impact on proliferation, apoptosis and migration processes. Moreover, genetic aberrations in WWOX induce severe neuropathological phenotypes in humans and rodents. The aim of the present study was to investigate in detail the impact of WWOX on human neural progenitor cell (hNPC) maintenance and how depletion of WWOX disturbs signaling pathways playing a pivotal role in neuronal differentiation and central nervous system (CNS) organogenesis. hNPC with a silenced WWOX gene exhibited lowered mitochondrial redox potential, enhanced adhesion to fibronectin and extracellular matrix protein mixture, downregulation of MMP2/9 expression and impaired 3D growth. Global transcriptome analysis using cap analysis of gene expression (CAGE) found that WWOX downregulation significantly changes the expression of multiple genes engaged in cytoskeleton organization, adhesion, cell signaling and chromatin remodeling. The massive changes in gene expression caused by WWOX silencing may strongly affect the differentiation and migration of neurons in organogenesis, brain injury, cancerogenesis or neurodifferentiation. WWOX gene appears to be an important regulator of neural tissue architecture and function.

Phosphorylation/de-phosphorylation in specific sites of tumor suppressor WWOX and control of distinct biological events

Abnormal differentiation and growth of hematopoietic stem cells cause the development of hematopoietic diseases and hematopoietic malignancies. However, the molecular events underlying leukemia development are not well understood. In our recent study, we have demonstrated that calcium ionophore and phorbol ester force the differentiation of T lymphoblastic leukemia. The event involves a newly identified IκBα/WWOX/ERK signaling, in which WWOX is Ser14 phosphorylated. Additional evidence also reveals that pS14-WWOX is involved in enhancing cancer progression and metastasis and facilitating neurodegeneration. In this mini-review, we update the current knowledge for the functional roles of WWOX under physiological and pathological settings, and provide new insights regarding pS14-WWOX in T leukemia cell maturation, and switching the anticancer pY33-WWOX to pS14-WWOX for cancer promotion and disease progression. Impact statement WWOX was originally designated as a tumor suppressor. However, human newborns deficient in WWOX do not spontaneously develop tumors. Activated WWOX with Tyr33 phosphorylation is present in normal tissues and organs. However, when pY33-WWOX is overly induced under stress conditions, it becomes apoptotic to eliminate damaged cells. Notably, WWOX with Ser14 phosphorylation is upregulated in the lesions of cancer, as well as in the brain hippocampus and cortex with Alzheimer's disease. Suppression of pS14-WWOX by Zfra reduces cancer growth and mitigates Alzheimer's disease progression, suggesting that pS14-WWOX facilitates disease progression. pS14-WWOX can be regarded as a marker of disease progression.

Unlocking the NF-κB Conundrum: Embracing Complexity to Achieve Specificity

Transcription factors of the nuclear factor κB (NF-κB) family are central coordinating regulators of the host defence responses to stress, injury and infection. Aberrant NF-κB activation also contributes to the pathogenesis of some of the most common current threats to global human health, including chronic inflammatory diseases, autoimmune disorders, diabetes, vascular diseases and the majority of cancers. Accordingly, the NF-κB pathway is widely considered an attractive therapeutic target in a broad range of malignant and non-malignant diseases. Yet, despite the aggressive efforts by the pharmaceutical industry to develop a specific NF-κB inhibitor, none has been clinically approved, due to the dose-limiting toxicities associated with the global suppression of NF-κB. In this review, we summarise the main strategies historically adopted to therapeutically target the NF-κB pathway with an emphasis on oncology, and some of the emerging strategies and newer agents being developed to pharmacologically inhibit this pathway.

Loss of lung WWOX expression causes neutrophilic inflammation

The tumor suppressor WW domain-containing oxidoreductase (WWOX) exhibits regulatory interactions with an array of transcription factors and signaling molecules that are positioned at the well-known crossroads between inflammation and cancer. WWOX is also subject to downregulation by genotoxic environmental exposures, making it of potential interest to the study of lung pathobiology. Knockdown of lung WWOX expression in mice was observed to cause neutrophil influx and was accompanied by a corresponding vascular leak and inflammatory cytokine production. In cultured human alveolar epithelial cells, loss of WWOX expression resulted in increased c-Jun- and IL-8-dependent neutrophil chemotaxis toward cell monolayers. WWOX was observed to directly interact with c-Jun in these cells, and its absence resulted in increased nuclear translocation of c-Jun. Finally, inhibition of the c-Jun-activating kinase JNK abrogated the lung neutrophil influx observed during WWOX knockdown in mice. Altogether, these observations represent a novel mechanism of pulmonary neutrophil influx that is highly relevant to the pathobiology and potential treatment of a number of different lung inflammatory conditions.

Role of WW Domain-containing Oxidoreductase WWOX in Driving T Cell Acute Lymphoblastic Leukemia Maturation

Whether tumor suppressor WWOX (WW domain-containing oxidoreductase) stimulates immune cell maturation is largely unknown. Here, we determined that Tyr-33-phosphorylated WWOX physically binds non-phosphorylated ERK and IκBα in immature acute lymphoblastic leukemia MOLT-4 T cells and in the naïve mouse spleen. The IκBα·ERK·WWOX complex was shown to localize, in part, in the mitochondria. WWOX prevents IκBα from proteasomal degradation. Upon stimulating MOLT-4 with ionophore A23187/phorbol myristate acetate, endogenous IκBα and ERK undergo rapid phosphorylation in <5 min, and subsequently WWOX is Tyr-33 and Tyr-287 de-phosphorylated and Ser-14 phosphorylated. Three hours later, IκBα starts to degrade, and ERK returns to basal or non-phosphorylation, and this lasts for the next 12 h. Finally, expression of CD3 and CD8 occurs in MOLT-4 along with reappearance of the IκBα·ERK·WWOX complex near 24 h. Inhibition of ERK phosphorylation by U0126 or IκBα degradation by MG132 prevents MOLT-4 maturation. By time-lapse FRET microscopy, IκBα·ERK·WWOX complex exhibits an increased binding strength by 1-2-fold after exposure to ionophore A23187/phorbol myristate acetate for 15-24 h. Meanwhile, a portion of ERK and WWOX relocates to the nucleus, suggesting their role in the induction of CD3 and CD8 expression in MOLT-4.

UV irradiation/cold shock-mediated apoptosis is switched to bubbling cell death at low temperatures

When COS7 fibroblasts and other cells were exposed to UVC irradiation and cold shock at 4°C for 5 min, rapid upregulation and nuclear accumulation of NOS2, p53, WWOX, and TRAF2 occurred in 10-30 min. By time-lapse microscopy, an enlarging gas bubble containing nitric oxide (NO) was formed in the nucleus in each cell that finally popped out to cause "bubbling death". Bubbling occurred effectively at 4 and 22°C, whereas DNA fragmentation was markedly blocked at 4°C. When temperature was increased to 37°C, bubbling was retarded and DNA fragmentation occurred in 1 hr, suggesting that bubbling death is switched to apoptosis with increasing temperatures. Bubbling occurred prior to nuclear uptake of propidium iodide and DAPI stains. Arginine analog Nω-LAME inhibited NO synthase NOS2 and significantly suppressed the bubbling death. Unlike apoptosis, there were no caspase activation and flip-over of membrane phosphatidylserine (PS) during bubbling death. Bubbling death was significantly retarded in Wwox knockout MEF cells, as well as in cells overexpressing TRAF2 and dominant-negative p53. Together, UV/cold shock induces bubbling death at 4°C and the event is switched to apoptosis at 37°C. Presumably, proapoptotic WWOX and p53 block the protective TRAF2 to execute the bubbling death.

Genomics of Esophageal Cancer and Biomarkers for Early Detection

In-depth molecular characterization of esophageal oncogenesis has improved over the recent years. Advancement in molecular biology and bioinformatics has led to better understanding of its genomic landscape. More specifically, analysis of its pathogenesis at the genetic level has uncovered the involvement of a number of tumor suppressor genes, cell cycle regulators, and receptor tyrosine kinases. Due to its poor prognosis, the development of clinically applicable biomarkers for diagnosis, progression, and treatment has been the focus of many research studies concentrating on upper gastrointestinal malignancies. As in other cancers, early detection and subsequent intervention of the preneoplastic condition significantly improves patient outcomes. Currently, clinically approved surveillance practices heavily depend on expensive, invasive, and sampling-error-prone endoscopic procedures. There is, therefore, a great demand to establish clearly reliable biomarkers that could identify those patients at higher risk of neoplastic progression and hence would greatly benefit from further monitoring and/or intervention. This chapter will present the most recent advances in the analysis of the esophageal cancer genome serving as basis for biomarker development.

WW domain-containing oxidoreductase in neuronal injury and neurological diseases

The human and mouse WWOX/Wwox gene encodes a candidate tumor suppressor WW domain-containing oxidoreductase protein. This gene is located on a common fragile site FRA16D. WWOX participates in a variety of cellular events and acts as a transducer in the many signal pathways, including TNF, chemotherapeutic drugs, UV irradiation, Wnt, TGF-β, C1q, Hyal-2, sex steroid hormones, and others. While transiently overexpressed WWOX restricts relocation of transcription factors to the nucleus for suppressing cancer survival, physiological relevance of this regard in vivo has not been confirmed. Unlike many tumor suppressor genes, mutation of WWOX is rare, raising a question whether WWOX is a driver for cancer initiation. WWOX/Wwox was initially shown to play a crucial role in neural development and in the pathogenesis of Alzheimer's disease and neuronal injury. Later on, WWOX/Wwox was shown to participate in the development of epilepsy, mental retardation, and brain developmental defects in mice, rats and humans. Up to date, most of the research and review articles have focused on the involvement of WWOX in cancer. Here, we review the role of WWOX in neural injury and neurological diseases, and provide perspectives for the WWOX-regulated neurodegeneration.

Introduction to a thematic issue for WWOX

Since its discovery in 2000, WW domain-containing oxidoreductase (WWOX, FOR or WOX1) has been considered as a tumor suppressor protein. Global research focus has been aimed mainly toward this direction. In this thematic issue, updated information has been collected regarding the structure, function and signaling of WWOX, along with its critical role as a tumor suppressor and participation in metabolism, neurodegeneration, ataxia, epilepsy, neural disorders, neuronal damages, and interactions with oncogenic viruses. WWOX is not a driver of cancer initiation. Chromosomal alterations in the WWOX gene enhance cancer progression. Importantly, a homozygous nonsense mutation of WWOX gene in humans leads to neural pathologies and early death, rather than spontaneous cancer development. These findings suggest new physiological functions of WWOX in metabolism and neural diseases, and these areas require further investigation.

The potential role of the glycoprotein osteoactivin/glycoprotein nonmetastatic melanoma protein B in pancreatic cancer

OBJECTIVES

Pancreatic ductal adenocarcinoma is still one of the deadliest solid cancers so the finding of new therapeutic approaches and novel targets are of utmost importance. Glycoprotein nonmetastatic melanoma protein B (GPNMB), initially termed glycoprotein nonmetastatic gene B and also named osteoactivin (OA), is a type 1 transmembrane protein that has been recently found to play a role in cancer cell proliferation, angiogenesis, and invasion. Due to its potential responsibility in cancer aggressiveness, the main objective of this work was to assess the role of GPNMB/OA in human pancreatic cancer.

METHODS

Using the human pancreatic cancer cell line Panc-1 in vitro, the effects of GPNMB on growth, proliferation, and invasion were tested by BrdU uptake, cell cycle and Annexin V-FITC analysis, RT-PCR, protein expression, and invasion chamber assays.

RESULTS

Our results showed that GPNMB/OA protein expression prevents cells from apoptosis-enhancing proliferation and represents a novel modulator of the invasion and metastasis in pancreatic cancer cells.

CONCLUSIONS

Due to its main membrane localization in cancer cells and its role in the aggressiveness of pancreatic cancer, GPNMB/OA could represent a novel targeted therapy for pancreatic cancer being attractive for antibody-based therapies.