FBXW7-mediated ERK3 degradation regulates the proliferation of lung cancer cells

CREG1 attenuates doxorubicin-induced cardiotoxicity by inhibiting the ferroptosis of cardiomyocytes

OBJECTIVE

Doxorubicin (DOX)-induced cardiotoxicity limits the application of DOX in cancer patients. Currently, there is no effective prevention or treatment for DOX-induced cardiotoxicity. The cellular repressor of E1A-stimulated genes (CREG1) is a cardioprotective factor that plays an important role in the maintenance of cardiomyocytes differentiation and homeostasis. However, the role and mechanism of CREG1 in DOX-induced cardiotoxicity has not yet been elucidated.

METHODS

In vivo, C57BL/6J mice, CREG1 transgenic and cardiac-specific CREG1 knockout mice were used to establish a DOX-induced cardiotoxicity model. H&E staining, Masson's trichrome, WGA staining, real-time PCR, and western blotting were performed to examine fibrosis and ferroptosis in the myocardium. In vitro, neonatal mouse cardiomyocytes (NMCMs) were cultured and stimulated with DOX, CREG1-overexpressed adenovirus, and small interfering RNA was used to establish CREG1 overexpression or knockdown cardiomyocytes. Transcriptomics, real-time PCR, western blotting, and immunoprecipitation were used to examine the roles and mechanisms of CREG1 in cardiomyocytes ferroptosis.

RESULTS

The mRNA and protein levels of CREG1 were reduced in the hearts and NMCMs after DOX treatment. CREG1 overexpression alleviated myocardial damage and inhibited DOX-induced ferroptosis in the myocardium. CREG1 deficiency in the heart aggravated DOX-induced cardiotoxicity and ferroptosis. In vitro, CREG1 overexpression inhibited cardiomyocytes ferroptosis induced by DOX, and CREG1 knockdown aggravated DOX-induced cardiotoxicity. Mechanistically, CREG1 inhibited the mRNA and protein expression of pyruvate dehydrogenase kinase 4 (PDK4) by regulating the F-box and WD repeat domain containing 7 (FBXW7)-forkhead box O1 (FOXO1) pathway. PDK4 deficiency reversed the effects of CREG1 knockdown on cardiomyocytes ferroptosis following DOX treatment.

CONCLUSION

CREG1 alleviated DOX-induced cardiotoxicity by inhibiting ferroptosis in cardiomyocytes. Our findings may help clarify the new roles of CREG1 in the development of DOX-induced cardiotoxicity.

CALU promotes lung adenocarcinoma progression by enhancing cell proliferation, migration and invasion

BACKGROUND

Lung cancer is the second most common cancer with the highest mortality in the world. Calumenin as a molecular chaperone that not only binds various proteins within the endoplasmic reticulum but also plays crucial roles in diverse processes associated with tumor development. However, the regulatory mechanism of calumenin in lung adenocarcinoma remains elusive. Here, we studied the impact of calumenin on lung adenocarcinoma and explored possible mechanisms.

METHODS

5-ethynyl-2'-deoxyuridine assay, colony formation, transwell and wound healing assays were performed to explore the effects of calumenin on the proliferation and migration of lung adenocarcinoma cells. To gain insights into the underlying mechanisms through which calumenin knockdown inhibits the migration and proliferation of lung adenocarcinoma, we performed Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Gene Set Enrichment Analysis and Ingenuity Pathway Analysis based on transcriptomics by comparing calumenin knockdown with normal A549 cells.

RESULTS

The mRNA and protein levels of calumenin in lung adenocarcinoma are highly expressed and they are related to an unfavorable prognosis in this disease. Calumenin enhances the proliferation and migration of A549 and H1299 cells. Gene Set Enrichment Analysis revealed that knockdown of calumenin in A549 cells significantly inhibited MYC and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog signaling pathways while activating interferon signals, inflammatory signals, and p53 pathways. Ingenuity pathway analysis provided additional insights, indicating that the interferon and inflammatory pathways were prominently activated upon calumenin knockdown in A549 cells.

CONCLUSIONS

The anti-cancer mechanism of calumenin knockdown might be related to the inhibition of MYC and KRAS signals but the activation of interferon signals, inflammatory signals and p53 pathways.

Advances of E3 ligases in lung cancer

Lung cancer is a leading cause of cancer-related death, and the most common type of lung cancer is non-small cell lung cancer, which accounts for approximately 85 % of lung cancer diagnoses. Recent studies have revealed that ubiquitination acts as a crucial part of the development and progression of lung cancer. The E1-E2-E3 three-enzyme cascade has a core function in ubiquitination, so targeted adjustments of E3 ligases could be used in lung cancer treatment. Hence, we elucidate research advances in lung cancer-related E3 ligases by briefly describing the structure and categorization of E3 ligases. Here, we provide a detailed review of the mechanisms by which lung cancer-related E3 ligases modify substrate proteins and regulate signaling pathways to facilitate or suppress cancer progression. We hope to show a new perspective on targeted precision therapy for lung cancer.

Role of the Atypical MAPK ERK3 in Cancer Growth and Progression

Extracellular signal-regulated kinase 3 (ERK3) is an atypical mitogen-activated protein kinase (MAPK) whose structural and regulatory features are distinct from those of conventional MAPKs, such as ERK1/2. Since its identification in 1991, the regulation, substrates and functions of ERK3 have remained largely unknown. However, recent years have witnessed a wealth of new findings about ERK3 signaling. Several important biological functions for ERK3 have been revealed, including its role in neuronal morphogenesis, inflammation, metabolism, endothelial cell tube formation and epithelial architecture. In addition, ERK3 has been recently shown to play important roles in cancer cell proliferation, migration, invasion and chemoresistance in multiple types of cancers. Furthermore, accumulating studies have uncovered various molecular mechanisms by which the expression level, protein stability and activity of ERK3 are regulated. In particular, several post-translational modifications (PTMs), including ubiquitination, hydroxylation and phosphorylation, have been shown to regulate the stability and activity of ERK3 protein. In this review, we discuss recent findings regarding biochemical and cellular functions of ERK3, with a main focus on its roles in cancers, as well as the molecular mechanisms of regulating its expression and activity.

KPNA2 Silencing, Regulated by E3 Ubiquitin Ligase FBXW7, Alleviates Endothelial Dysfunction and Inflammation Through Inhibiting the Nuclear Translocation of p65 and IRF3: A Possible Therapeutic Approach for Atherosclerosis

Atherosclerosis (AS), characterized by a maladaptive inflammatory response, is one of the most common causes of death among the elderly. Karyopherin subunit alpha 2 (KPNA2), a member of the nuclear transport protein family, has been reported to play a pro-inflammatory role in various pathological processes by regulating the nuclear translocation of pro-inflammatory transcription factors. However, the function of KPNA2 in AS remains unknown. ApoE-/- mice were fed high-fat diets for 12 weeks to establish an AS mice model. Human umbilical vein endothelial cells (HUVECs) were treated with lipopolysaccharide (LPS) to establish an AS cell model. We found that KPNA2 was upregulated in the aortic roots of atherosclerotic mice and LPS-stimulated cells. KPNA2 knockdown inhibited LPS-induced secretion of pro-inflammatory factors and monocyte-endothelial adhesion in HUVECs, whereas KPNA2 overexpression exerted the opposite effects. p65 and interferon regulatory factor 3 (IRF3), the transcription factors known to regulate the transcription of pro-inflammatory genes, interacted with KPNA2, and their nuclear translocations were blocked following KPNA2 silencing. Furthermore, we found that KPNA2 protein level was decreased by E3 ubiquitin ligase F-box and WD repeat domain containing 7 (FBXW7), which was downregulated in the atherosclerotic mice. FBXW7 overexpression induced ubiquitination with subsequent proteasomal degradation of KPNA2. Meanwhile, the effects of KPNA2 deficiency on atherosclerotic lesions were further confirmed by in vivo experiments. Taken together, our study indicates that KPNA2 downregulation, regulated by FBXW7, may alleviate endothelial dysfunction and related inflammation in the progression of AS by suppressing the nuclear translocation of p65 and IRF3.

Transcriptomics Provides Novel Insights into the Regulatory Mechanism of IncRNA HIF1 A-AS1 on Vascular Smooth Muscle Cells

INTRODUCTION

Thoracic aortic aneurysm is a potentially fatal disease with a strong genetic contribution. The dysfunction of vascular smooth muscle cells (VSMCs) contributes to the formation of this aneurysm. Although previous studies suggested that long non-coding ribonucleic acid (RNA) hypoxia inducible factor 1 α-antisense RNA 1 (HIF1A-AS1) exerted a vital role in the progression and pathogenesis of thoracic aortic aneurysm, we managed to find a new regulatory mechanism of HIF1A-AS1 in VSMCs via transcriptomics.

METHODS

Cell viability was detected by the cell counting kit-8 assay. Cell apoptosis was assessed by Annexin V-fluorescein isothiocyanate/propidium iodide double staining. Transwell migration assay and wound healing assay were performed to check the migration ability of HIF1A-AS1 on VSMCs. The NextSeq XTen system (Illumina) was used to collect RNA sequencing data. Lastly, reverse transcription-quantitative polymerase chain reaction confirmed the veracity and reliability of RNA-sequencing results.

RESULTS

We observed that overexpressing HIF1A-AS1 successfully promoted apoptosis, significantly altered cell cycle distribution, and greatly attenuated migration in VSMCs, further highlighting the robust promoting effects of HIF1A-AS1 to thoracic aortic aneurysm. Moreover, transcriptomics was implemented to uncover its underlying mechanism. A total of 175 differently expressed genes were identified, with some of them enriched in apoptosis, migration, and cell cycle-related pathways. Intriguingly, some differently expressed genes were noted in vascular development or coagulation function pathways.

CONCLUSION

We suggest that HIF1A-AS1 mediated the progression of thoracic aortic aneurysm by not only regulating the function of VSMCs, but also altering vascular development or coagulation function.

Genome-wide analysis of WD40 protein family and functional characterization of BvWD40-82 in sugar beet

Sugar beet is one of the most important sugar crops in the world. It contributes greatly to the global sugar production, but salt stress negatively affects the crop yield. WD40 proteins play important roles in plant growth and response to abiotic stresses through their involvement in a variety of biological processes, such as signal transduction, histone modification, ubiquitination, and RNA processing. The WD40 protein family has been well-studied in Arabidopsis thaliana, rice and other plants, but the systematic analysis of the sugar beet WD40 proteins has not been reported. In this study, a total of 177 BvWD40 proteins were identified from the sugar beet genome, and their evolutionary characteristics, protein structure, gene structure, protein interaction network and gene ontology were systematically analyzed to understand their evolution and function. Meanwhile, the expression patterns of BvWD40s under salt stress were characterized, and a BvWD40-82 gene was hypothesized as a salt-tolerant candidate gene. Its function was further characterized using molecular and genetic methods. The result showed that BvWD40-82 enhanced salt stress tolerance in transgenic Arabidopsis seedlings by increasing the contents of osmolytes and antioxidant enzyme activities, maintaining intracellular ion homeostasis and increasing the expression of genes related to SOS and ABA pathways. The result has laid a foundation for further mechanistic study of the BvWD40 genes in sugar beet tolerance to salt stress, and it may inform biotechnological applications in improving crop stress resilience.

ERK3 and DGKζ interact to modulate cell motility in lung cancer cells

Extracellular signal-regulated kinase 3 (ERK3) promotes cell migration and tumor metastasis in multiple cancer types, including lung cancer. The extracellular-regulated kinase 3 protein has a unique structure. In addition to the N-terminal kinase domain, ERK3 includes a central conserved in extracellular-regulated kinase 3 and ERK4 (C34) domain and an extended C-terminus. However, relatively little is known regarding the role(s) of the C34 domain. A yeast two-hybrid assay using extracellular-regulated kinase 3 as bait identified diacylglycerol kinase ζ (DGKζ) as a binding partner. DGKζ was shown to promote migration and invasion in some cancer cell types, but its role in lung cancer cells is yet to be described. The interaction of extracellular-regulated kinase 3 and DGKζ was confirmed by co-immunoprecipitation and in vitro binding assays, consistent with their co-localization at the periphery of lung cancer cells. The C34 domain of ERK3 was sufficient for binding to DGKζ, while extracellular-regulated kinase 3 bound to the N-terminal and C1 domains of DGKζ. Surprisingly, in contrast to extracellular-regulated kinase 3, DGKζ suppresses lung cancer cell migration, suggesting DGKζ might inhibit ERK3-mediated cell motility. Indeed, co-overexpression of exogenous DGKζ and extracellular-regulated kinase 3 completely blocked the ability of ERK3 to promote cell migration, but DGKζ did not affect the migration of cells with stable ERK3 knockdown. Furthermore, DGKζ had little effect on cell migration induced by overexpression of an ERK3 mutant missing the C34 domain, suggesting DGKζ requires this domain to prevent ERK3-mediated increase in cell migration. In summary, this study has identified DGKζ as a new binding partner and negative regulator of extracellular-regulated kinase 3 in controlling lung cancer cell migration.

WD repeat protein 54-mediator of ErbB2-driven cell motility 1 axis promotes bladder cancer tumorigenesis and metastasis and impairs chemosensitivity

One of the most abundant protein-protein interaction domains in the human proteome is the WD40 repeat (WDR) domain. A Gene Expression Omnibus dataset revealed 37 differentially expressed WDR domain genes in bladder cancer (BC). WD repeat domain 54 (WDR54), an upregulated WDR domain gene, was selected for further investigation. Sixty pairs of frozen BC tumor and non-malignant bladder tissues and 83 paraffin-embedded BC tissue specimens were obtained. Loss-/gain-of-function experiments were carried out using BC and xenograft tumor models. WDR54 was overexpressed in BC cells, and its high expression was linked to tumor stage and lymph node metastases in patients. WDR54 contributed to the tumorigenesis and metastasis of BC and impaired its chemosensitivity. WDR54 prevented the degradation and ubiquitination of the mediator of ErbB2-driven cell motility 1 (MEMO1). WDR54 also promoted the interaction between MEMO1 and insulin receptor substrate 1 (IRS1) and activated the IRS1/AKT/β-catenin pathway in BC cells. Particularly, WDR54 depended on MEMO1 to exert its biological functions. Our study demonstrated the relevance of WDR54 in BC and provides insight into the molecular mechanism underlying BC.

The E3 ubiquitin ligase SCF (FBXW10)-mediated LATS2 degradation regulates angiogenesis and liver metastasis in colorectal cancer

F-box and WD repeat domain containing 10 (FBXW10) is a member of the FBXW subgroup that contains the WD40 domain. FBXW10 has been rarely reported in colorectal cancer (CRC) and its mechanism is unclear. To investigate the role of FBXW10 in CRC, we conducted in vitro and in vivo experiments. Through the database and our clinical samples, we found that FBXW10 expression was up-regulated in CRC, and it was positively correlated with CD31 expression. CRC patients with high FBXW10 expression levels had a poor prognosis. Overexpression of FBXW10 up-regulated cell proliferation, migration and vascular formation, while knockdown of FBXW10 had the opposite effects. Studies on the mechanism of FBXW10 in CRC showed that FBXW10 could ubiquitinate large tumor suppressor kinase 2 (LATS2) and promote its degradation with the Fbox region of FBXW10 played an essential role in this process. In vivo studies demonstrated that knockout of FBXW10 inhibited tumor proliferation and reduced liver metastasis. In conclusion, our study proved that FBXW10 was significantly overexpressed in CRC and was involved in the pathogenesis of CRC by affecting angiogenesis and liver metastasis. Mechanistically, FBXW10 degraded LATS2 through ubiquitination. Therefore, FBXW10-LATS2 can be used as a therapeutic target for CRC in subsequent studies.

MEKs/ERKs-mediated FBXO1/E2Fs interaction interference modulates G1/S cell cycle transition and cancer cell proliferation

E2F 1, 2, and 3a, (refer to as E2Fs) are a subfamily of E2F transcription factor family that play essential roles in cell-cycle progression, DNA replication, DNA repair, apoptosis, and differentiation. Although the transcriptional regulation of E2Fs has focused on pocket protein retinoblastoma protein complex, recent studies indicate that post-translational modification and stability regulation of E2Fs play key roles in diverse cellular processes. In this study, we found that FBXO1, a component of S-phase kinase-associated protein 1 (SKP1)-cullin 1-F-box protein (SCF) complex, is an E2Fs binding partner. Furthermore, FBXO1 to E2Fs binding induced K48 ubiquitination and subsequent proteasomal degradation of E2Fs. Binding domain analysis indicated that the Arg (R)/Ile (I) and R/Val (V) motifs, which are located in the dimerization domain of E2Fs, of E2F 1 and 3a and E2F2, respectively, acted as degron motifs (DMs) for FBXO1. Notably, RI/AA or RV/AA mutation in the DMs reduced FBXO1-mediated ubiquitination and prolonged the half-lives of E2Fs. Importantly, the stabilities of E2Fs were affected by phosphorylation of threonine residues located near RI and RV residues of DMs. Phosphorylation prediction database analysis and specific inhibitor analysis revealed that MEK/ERK signaling molecules play key roles in FBXO1/E2Fs' interaction and modulate E2F protein turnover. Moreover, both elevated E2Fs protein levels by knockdown of FBXO1 and decreased E2Fs protein levels by sh-E2F3a delayed G₁/S cell cycle transition, resulting in inhibition of cancer cell proliferation. These results demonstrated that FBXO1-E2Fs axis-mediated precise E2Fs stability regulation plays a key role in cell proliferation via G₁/S cell cycle transition.

Molecular mechanism of FBXW7-mediated ubiquitination modification in nasopharyngeal carcinoma cell proliferation in vitro and in vivo

OBJECTIVES

Nasopharyngeal carcinoma (NPC) is a type of keratinizing squamous cell malignancy. Ubiquitination, a common protein posttranslational modification, participates in cancer development. This study sought to investigate the mechanism of F-box and WD repeat domain containing 7 (FBXW7) in NPC cell proliferation in vivo and in vitro.

METHODS

FBXW7, Homeobox A10 (HOXA10), and bone morphogenetic protein-2 (BMP2) expression levels in NPC tissues and cells were detected by RT-qPCR and Western blotting. Cell proliferation was assessed by cell counting kit-8 and colony formation assays. The binding of FBXW7 to HOXA10 and HOXA10 ubiquitination level were detected via co-immunoprecipitation and ubiquitination assay. Cells were treated with MG132 (the proteasome inhibitor), followed by the determination of HOXA10 ubiquitination and protein levels. The binding of HOXA10 to BMP2 was testified via dual-luciferase and chromatin immunoprecipitation assays. Collaborative experiments were performed to confirm the role of HOXA10 or BMP2 in FBXW7-mediated NPC cell proliferation. Xenograft tumor assay was performed to confirm the role of FBXW7/HOXA10/BMP2 in vivo.

RESULTS

FBXW7 was under-expressed, while HOXA10 and BMP2 were up-expressed in NPC tissues and cells. FBXW7 overexpression restricted NPC cell proliferation. Mechanically, FBXW7 bound to HOXA10 to promote ubiquitination-based degradation of HOXA10 and further reduced the binding of HOXA10 to the BMP2 promoter and inhibited BMP2 transcription. Overexpression of HOXA10 or BMP2 attenuated the role of FBXW7 overexpression in inhibiting NPC cell proliferation. FBXW7 overexpression reduced Ki67 positive rate and repressed tumor growth.

CONCLUSION

FBXW7 overexpression promoted HOXA10 ubiquitination-based degradation and further inhibited BMP2 transcription, consequently restricting NPC cell proliferation in vitro and in vivo.