Wnt/β-catenin signaling and p68 conjointly regulate CHIP in colorectal carcinoma

Belling the "cat": Wnt/β-catenin signaling and its significance in future cancer therapies

The WNT/β-catenin is among one of the most extensively studied cellular signaling pathways involved in the initiation and progression of several deadly cancers. It is now understood that the WNT/β-catenin signaling, during tumor progression operates in a very complex fashion beyond the earlier assumed simple WNT 'On' or 'Off' mode as it recruits numerous WNT ligands, receptors, transcriptional factors and also cross-talks with other signaling molecules including the noncanonical WNT regulators. WNT/β-catenin signaling molecules are often mutated in different cancers which makes them very challenging to inhibit and sometimes ranks them among the undruggable targets. Furthermore, due to the evolutionary conservation of this pathway, inhibiting WNT/β-catenin has caused significant toxicity in normal cells. These challenges are reflected in clinical trial data, where the use of WNT/β-catenin inhibitors as standalone treatments remains limited. In this review, we have highlighted the crucial functional associations of diverse WNT/β-catenin signaling regulators with cancer progression and the phenotypic switching of tumor cells. Next, we have shed light on the roles of WNT/β-catenin signaling in drug resistance, clonal evolution, tumor heterogeneity, and immune evasion. The present review also focuses on various classes of routine and novel WNT/β-catenin therapeutic regimes while addressing the challenges associated with targeting the regulators of this complex pathway. In the light of multiple case studies on WNT/β-catenin inhibitors, we also highlighted the challenges and opportunities for future clinical trial strategies involving these treatments. Additionally, we have proposed strategies for future WNT/β-catenin-based drug discovery trials, emphasizing the potential of combination therapies and AI/ML-driven prediction approaches. Overall, here we showcased the opportunities, possibilities, and potentialities of WNT/β-catenin signaling modulatory therapeutic regimes as promising precision cancer medicines for the future.

Acute exposure to polystyrene nanoplastics induces unfolded protein response and global protein ubiquitination in lungs of mice

Inhaling microplastics (MPs) and nanoplastics (NPs) in the air can damage lung function. Xenobiotics in the body can cause endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) activation alleviates ER stress. Degradation of unfolded or misfolded proteins is an important pathway for recovering cellular homeostasis. The UPR and protein degradation induced by MPs/NPs in lung tissues are not well understood. Here, we investigated the UPR and protein ubiquitination in the lungs of mice exposed to polystyrene (PS)-NPs and their possible molecular mechanisms leading to protein ubiquitination. Mice were intratracheally administered with 5.6, 17, and 51 mg/kg PS-NPs once for 24 h. Exposure to PS-NPs elevated protein ubiquitination in the lungs of mice in a dose-dependent manner. PS-NPs activated three branches of UPR including inositol-requiring protein 1α (IRE1α), eukaryotic translation initiator factor 2α (eIF2α), and activating transcription factor 6α (ATF6α) in the lungs of mice. However, activated IRE1α did not trigger X-box binding protein 1 (XBP1) mRNA splicing. Exposure to PS-NPs induced an increase in the levels of E3 ubiquitin ligase hydroxymethyl glutaryl-coenzyme A reductase degradation protein 1 (HRD1) and carboxy terminus of Hsc70 interacting protein (CHIP) in the lungs of mice and BEAS-2B cells. ATF6α siRNA inhibited the levels of HRD1 and CHIP proteins induced by PS-NPs in BEAS-2B cells. These results suggest that ATF6α plays a critical role in increasing ubiquitination of unfolded or misfolded proteins by alleviating PS-NPs induced ER stress through UPR to achieve ER homeostasis in the lungs of mice.

FL118 Is a Potent Therapeutic Agent against Chronic Myeloid Leukemia Resistant to BCR-ABL Inhibitors through Targeting RNA Helicase DDX5

Chronic myeloid leukemia (CML) is induced by the expression of the fused tyrosine kinase BCR-ABL, which is caused by a chromosomal translocation. BCR-ABL inhibitors have been used to treat CML; however, the acquisition of resistance by CML cells during treatment is a serious issue. We herein demonstrated that BCR-ABL induced the expression of the RNA helicase DDX5 in K562 cells derived from CML patients in a manner that was dependent on its kinase activity, which resulted in cell proliferation and survival. The knockout of DDX5 decreased the expression of BIRC5 (survivin) and activated caspase 3, leading to apoptosis in K562 cells. Similar results were obtained in cells treated with FL118, an inhibitor of DDX5 and a derivative compound of camptothecin (CPT). Furthermore, FL118 potently induced apoptosis not only in Ba/F3 cells expressing BCR-ABL, but also in those expressing the BCR-ABL T315I mutant, which is resistant to BCR-ABL inhibitors. Collectively, these results revealed that DDX5 is a critical therapeutic target in CML and that FL118 is an effective candidate compound for the treatment of BCR-ABL inhibitor-resistant CML.

MGMT in TMZ-based glioma therapy: Multifaceted insights and clinical trial perspectives

Temozolomide (TMZ) is the most preferred and approved chemotherapeutic drug for either first- or second-line chemotherapy for glioma patients across the globe. In glioma patients, resistance to treatment with alkylating drugs like TMZ is known to be conferred by exalted levels of MGMT gene expression. On the contrary, epigenetic silencing through MGMT gene promoter methylation leading to subsequent reduction in MGMT transcription and protein expression, is predicted to have a response favoring TMZ treatment. Thus, MGMT protein level in cancer cells is a crucial determining factor in indicating and predicting the choice of alkylating agents in chemotherapy or choosing glioma patients directly for a second line of treatment. Thus, in-depth research is necessary to achieve insights into MGMT gene regulation that has recently enticed a fascinating interest in epigenetic, transcriptional, post-transcriptional, and post-translational levels. Furthermore, MGMT promoter methylation, stability of MGMT protein, and related subsequent adaptive responses are also important contributors to strategic developments in glioma therapy. With applications to its identification as a prognostic biomarker, thus predicting response to advanced glioma therapy, this review aims to concentrate on the mechanistic role and regulation of MGMT gene expression at epigenetic, transcriptional, post-transcriptional, and post-translational levels functioning under the control of multiple signaling dynamics.

VAMP8 suppresses the metastasis via DDX5/β-catenin signal pathway in osteosarcoma

Osteosarcoma is a highly metastatic malignant bone tumor, necessitating the development of new treatments to target its metastasis. Recent studies have revealed the significance of VAMP8 in regulating various signaling pathways in various types of cancer. However, the specific functional role of VAMP8 in osteosarcoma progression remains unclear. In this study, we observed a significant downregulation of VAMP8 in osteosarcoma cells and tissues. Low levels of VAMP8 in osteosarcoma tissues were associated with patients' poor prognosis. VAMP8 inhibited the migration and invasion capability of osteosarcoma cells. Mechanically, we identified DDX5 as a novel interacting partner of VAMP8, and the conjunction of VAMP8 and DDX5 promoted the degradation of DDX5 via the ubiquitin-proteasome system. Moreover, reduced levels of DDX5 led to the downregulation of β-catenin, thereby suppressing the epithelial-mesenchymal transition (EMT). Additionally, VAMP8 promoted autophagy flux, which may contribute to the suppression of osteosarcoma metastasis. In conclusion, our study anticipated that VAMP8 inhibits osteosarcoma metastasis by promoting the proteasomal degradation of DDX5, consequently inhibiting WNT/β-catenin signaling and EMT. Dysregulation of autophagy by VAMP8 is also implicated as a potential mechanism. These findings provide new insights into the biological nature driving osteosarcoma metastasis and highlight the modulation of VAMP8 as a potential therapeutic strategy for targeting osteosarcoma metastasis.

DDX5 (p68) orchestrates β-catenin, RelA and SP1 mediated MGMT gene expression in human colon cancer cells: Implication in TMZ chemoresistance

DDX5 (p68) upregulation has been linked with various cancers of different origins, especially Colon Adenocarcinomas. Similarly, across cancers, MGMT has been identified as the major contributor of chemoresistance against DNA alkylating agents like Temozolomide (TMZ). TMZ is an emerging potent chemotherapeutic agent across cancers under the arena of drug repurposing. Recent studies have established that patients with open MGMT promoters are prone to be innately resistant or acquire resistance against TMZ compared to its closed conformation. However, not much is known about the transcriptional regulation of MGMT gene in the context of colon cancer. This necessitates studying MGMT gene regulation which directly impacts the cellular potential to develop chemoresistance against alkylating agents. Our study aims to uncover an unidentified mechanism of DDX5-mediated MGMT gene regulation. Experimentally, we found that both mRNA and protein expression levels of MGMT were elevated in response to p68 overexpression in multiple human colon cancer cell lines and vice-versa. Since p68 cannot directly interact with the MGMT promoter, transcription factors viz., β-catenin, RelA (p65) and SP1 were also studied as reported contributors. Through co-immunoprecipitation and GST-pull-down studies, p68 was established as an interacting partner of SP1 in addition to β-catenin and NF-κB (p50-p65). Mechanistically, luciferase reporter and chromatin-immunoprecipitation assays demonstrated that p68 interacts with the MGMT promoter via TCF4-LEF, RelA and SP1 sites to enhance its transcription. To the best of our knowledge, this is the first report of p68 as a transcriptional co-activator of MGMT promoter and our study identifies p68 as a novel and master regulator of MGMT gene expression.

Role and therapeutic potential of DEAD-box RNA helicase family in colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed and the second cancer-related death worldwide, leading to more than 0.9 million deaths every year. Unfortunately, this disease is changing rapidly to a younger age, and in a more advanced stage when diagnosed. The DEAD-box RNA helicase proteins are the largest family of RNA helicases so far. They regulate almost every aspect of RNA physiological processes, including RNA transcription, editing, splicing and transport. Aberrant expression and critical roles of the DEAD-box RNA helicase proteins have been found in CRC. In this review, we first summarize the protein structure, cellular distribution, and diverse biological functions of DEAD-box RNA helicases. Then, we discuss the distinct roles of DEAD-box RNA helicase family in CRC and describe the cellular mechanism of actions based on recent studies, with an aim to provide future strategies for the treatment of CRC.

The E3 ubiquitin ligase CHIP drives monoubiquitylation-mediated nuclear import of the tumor suppressor PTEN

Monoubiquitylation is a principal mechanism driving nuclear translocation of the protein PTEN (phosphatase and tensin homolog deleted on chromosome ten). In this study, we describe a novel mechanism wherein the protein CHIP (C-terminus of Hsc70-interacting protein) mediates PTEN monoubiquitylation, leading to its nuclear import. Western blot analysis revealed a rise in both nuclear and total cellular PTEN levels under monoubiquitylation-promoting conditions, an effect that was abrogated by silencing CHIP expression. We established time-point kinetics of CHIP-mediated nuclear translocation of PTEN using immunocytochemistry and identified a role of karyopherin α1 (KPNA1) in facilitating nuclear transport of monoubiquitylated PTEN. We further established a direct interaction between CHIP and PTEN inside the nucleus, with CHIP participating in either polyubiquitylation or monoubiquitylation of nuclear PTEN. Finally, we showed that oxidative stress enhanced CHIP-mediated nuclear import of PTEN, which resulted in increased apoptosis, and decreased cell viability and proliferation, whereas CHIP knockdown counteracted these effects. To the best of our knowledge, this is the first report elucidating non-canonical roles for CHIP on PTEN, which we establish here as a nuclear interacting partner of CHIP.

The DEAD-box RNA helicase DDX5 (p68) and β-catenin: The crucial regulators of FOXM1 gene expression in arbitrating colorectal cancer

Forkhead box M1 (FOXM1), a vital member of the Forkhead box family of transcription factors, helps in mediating oncogenesis. However, limited knowledge exists regarding the mechanistic insights into the FOXM1 gene regulation. DDX5 (p68), an archetypal member of the DEAD-box family of RNA helicases, shows multifaceted action in cancer progression by arbitrating RNA metabolism and transcriptionally coactivating transcription factors. Here, we report a novel mechanism of alliance between DDX5 (p68) and the Wnt/β-catenin pathway in regulating FOXM1 gene expression and driving colon carcinogenesis. Initial bioinformatic analyses highlighted elevated expression levels of FOXM1 and DDX5 (p68) in colorectal cancer datasets. Immunohistochemical assays confirmed that FOXM1 showed a positive correlation with DDX5 (p68) and β-catenin in both normal and colon carcinoma patient samples. Overexpression of DDX5 (p68) and β-catenin increased the protein and mRNA expression profiles of FOXM1, and the converse correlation occurred during downregulation. Mechanistically, overexpression and knockdown of DDX5 (p68) and β-catenin elevated and diminished FOXM1 promoter activity respectively. Additionally, Chromatin immunoprecipitation assay demonstrated the occupancy of DDX5 (p68) and β-catenin at the TCF4/LEF binding element (TBE) sites on the FOXM1 promoter. Thiostrepton delineated the effect of FOXM1 inhibition on cell proliferation and migration. Colony formation assay, migration assay, and cell cycle data reveal the importance of the DDX5 (p68)/β-catenin/FOXM1 axis in oncogenesis. Collectively, our study mechanistically highlights the regulation of FOXM1 gene expression by DDX5 (p68) and β-catenin in colorectal cancer.

DDX5 and DDX17—multifaceted proteins in the regulation of tumorigenesis and tumor progression

DEAD-box (DDX)5 and DDX17, which belong to the DEAD-box RNA helicase family, are nuclear and cytoplasmic shuttle proteins. These proteins are expressed in most tissues and cells and participate in the regulation of normal physiological functions; their abnormal expression is closely related to tumorigenesis and tumor progression. DDX5/DDX17 participate in almost all processes of RNA metabolism, such as the alternative splicing of mRNA, biogenesis of microRNAs (miRNAs) and ribosomes, degradation of mRNA, interaction with long noncoding RNAs (lncRNAs) and coregulation of transcriptional activity. Moreover, different posttranslational modifications, such as phosphorylation, acetylation, ubiquitination, and sumoylation, endow DDX5/DDX17 with different functions in tumorigenesis and tumor progression. Indeed, DDX5 and DDX17 also interact with multiple key tumor-promoting molecules and participate in tumorigenesis and tumor progression signaling pathways. When DDX5/DDX17 expression or their posttranslational modification is dysregulated, the normal cellular signaling network collapses, leading to many pathological states, including tumorigenesis and tumor development. This review mainly discusses the molecular structure features and biological functions of DDX5/DDX17 and their effects on tumorigenesis and tumor progression, as well as their potential clinical application for tumor treatment.

Integrative Analyses of Genes Associated With Otologic Disorders in Turner Syndrome

Background: Loss or partial loss of one X chromosome induces Turner syndrome (TS) in females, causing major medical concerns, including otologic disorders. However, the underlying genetic pathophysiology of otologic disorders in TS is mostly unclear.

Methods: Ear-related genes of TS (TSEs) were identified by analyzing differentially expressed genes (DEGs) in two Gene Expression Omnibus (GEO)-derived expression profiles and ear-genes in the Comparative Toxicogenomic Database (CTD). Subsequently, Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Disease Ontology (DO) analyses; Gene Set Enrichment Analysis (GSEA); and Gene Set Variation Analysis (GSVA) were adopted to study biological functions. Moreover, hub genes within the TSEs were identified by assessing protein-protein interaction (PPI), gene-microRNA, and gene-transcription factor (TF) networks. Drug-Gene Interaction Database (DGIdb) analysis was performed to predict molecular drugs for TS. Furthermore, three machine-learning analysis outcomes were comprehensively compared to explore optimal biomarkers of otologic disorders in TS. Finally, immune cell infiltration was analyzed.

Results: The TSEs included 30 significantly upregulated genes and 14 significantly downregulated genes. Enrichment analyses suggested that TSEs play crucial roles in inflammatory responses, phospholipid and glycerolipid metabolism, transcriptional processes, and epigenetic processes, such as histone acetylation, and their importance for inner ear development. Subsequently, we described three hub genes in the PPI network and confirmed their involvement in Wnt/β-catenin signaling pathway and immune cell regulation and roles in maintaining normal auditory function. We also constructed gene-microRNA and gene-TF networks. A novel biomarker (SLC25A6) of the pathogenesis of otologic disorders in TS was identified by comprehensive comparisons of three machine-learning analyses with the best predictive performance. Potential therapeutic agents in TS were predicted using the DGIdb. Immune cell infiltration analysis showed that TSEs are related to immune-infiltrating cells.

Conclusion: Overall, our findings have deepened the understanding of the pathophysiology of otologic disorders in TS and made contributions to present a promising biomarker and treatment targets for in-depth research.