NEDD9 Facilitates Hypoxia-Induced Gastric Cancer Cell Migration via MICAL1 Related Rac1 Activation

PlexinA1 promotes gastric cancer migration through preventing MICAL1 protein ubiquitin/proteasome-mediated degradation in a Rac1-dependent manner

Metastasis promotes the development of tumors and is a significant cause of gastric cancer death. For metastasis to proceed, tumor cells must become mobile by modulating their cytoskeleton. MICAL1 (Molecule Interacting with CasL1) is known as an actin cytoskeleton regulator, but the mechanisms by which it drives gastric cancer cell migration are still unclear. Analysis of gastric cancer tissues revealed that MICAL1 expression is dramatically upregulated in stomach adenocarcinoma (STAD) samples as compared to noncancerous stomach tissues. Patients with high MICAL1 expression had shorter overall survival (OS), post-progression survival (PPS) and first-progression survival (FPS) compared with patients with low MICAL1 expression. RNAi-mediated silencing of MICAL1 inhibited the expression of Vimentin, a protein involved in epithelial-mesenchymal transition. This effect correlates with a significant reduction in gastric cancer cell migration. MICAL1 overexpression reversed these preventive effects. Immunoprecipitation experiments and immunofluorescence assays revealed that PlexinA1 forms a complex with MICAL1. Importantly, specific inhibition of PlexinA1 blocked the Rac1 activation and ROS production, which, in turn, impaired MICAL1 protein stability by accelerating MICAL1 ubiquitin/proteasome-dependent degradation. Overexpression of PlexinA1 enhanced Rac1 activation, ROS production, MICAL1 and Vimentin expressions, and favored cell migration. In conclusion, this study identified MICAL1 as an important facilitator of gastric cancer cell migration, at least in part, by affecting Vimentin expression and PlexinA1 promotes gastric cancer cell migration by binding to and suppressing MICAL1 degradation in a Rac1/ROS-dependent manner.

Rac1: A Regulator of Cell Migration and A Potential Target for Cancer Therapy

Cell migration is crucial for physiological and pathological processes such as morphogenesis, wound repair, immune response and cancer invasion/metastasis. There are many factors affecting cell migration, and the regulatory mechanisms are complex. Rac1 is a GTP-binding protein with small molecular weight belonging to the Rac subfamily of the Rho GTPase family. As a key molecule in regulating cell migration, Rac1 participates in signal transduction from the external cell to the actin cytoskeleton and promotes the establishment of cell polarity which plays an important role in cancer cell invasion/metastasis. In this review, we firstly introduce the molecular structure and activity regulation of Rac1, and then summarize the role of Rac1 in cancer invasion/metastasis and other physiological processes. We also discuss the regulatory mechanisms of Rac1 in cell migration and highlight it as a potential target in cancer therapy. Finally, the current state as well as the future challenges in this area are considered. Understanding the role and the regulatory mechanism of Rac1 in cell migration can provide fundamental insights into Rac1-related cancer progression and further help us to develop novel intervention strategies for cancer therapy in clinic.

MICAL-mediated oxidation of actin and its effects on cytoskeletal and cellular dynamics

Actin and its dynamic structural remodelings are involved in multiple cellular functions, including maintaining cell shape and integrity, cytokinesis, motility, navigation, and muscle contraction. Many actin-binding proteins regulate the cytoskeleton to facilitate these functions. Recently, actin's post-translational modifications (PTMs) and their importance to actin functions have gained increasing recognition. The MICAL family of proteins has emerged as important actin regulatory oxidation-reduction (Redox) enzymes, influencing actin's properties both in vitro and in vivo. MICALs specifically bind to actin filaments and selectively oxidize actin's methionine residues 44 and 47, which perturbs filaments' structure and leads to their disassembly. This review provides an overview of the MICALs and the impact of MICAL-mediated oxidation on actin's properties, including its assembly and disassembly, effects on other actin-binding proteins, and on cells and tissue systems.

High MICAL1 expression correlates with cancer progression and immune infiltration in renal clear cell carcinoma

BACKGROUND

Molecule interacting with CasL 1 (MICAL1), a multidomain flavoprotein monooxygenase, is strongly involved in the biological processes related to cancer cell proliferation and metastasis. However, there were few reports on the clinical significance of MICAL1 in renal clear cell carcinoma.

METHODS

The expression and prognostic value of MICAL1 in renal clear cell carcinoma were explored using immunohistochemical assays, public TCGA-KIRC databases and multiple analysis methods, including survival analysis, univariate and multivariate analyses, KEGG and GSEA. Wound healing and Transwell assays were performed to check the 786-O cell and Caki-1 cell migration abilities after knockdown of MICAL1. Western blotting was used to assess the regulatory effect of MICAL1 on the Rac1 activation. Additionally, the function of MICAL1 and the correlations between MICAL1 and immune infiltration levels in KIRC were investigated using TIMER and TISIDB.

RESULTS

MICAL1 expression was significantly higher in carcinoma tissue compared with non-cancerous tissue. A survival analysis revealed that patients with high MICAL1 expression had shorter overall survival (OS) and disease-specific survival (DSS) compared with patients with low MICAL1 expression. ROC analysis also confirmed that MICAL1 has a high diagnostic value in KIRC. Importantly, the univariate and multivariate Cox analysis further confirmed that high MICAL1 expression was an independent risk factor for OS in patients with KIRC. In accordance with this, knockdown of MICAL1 expression decreased Rac1 activation and cell migration. KEGG and GSEA analysis revealed that the immune infiltration and Ras signaling pathways were significantly upregulated in the high MICAL1 expression group. In terms of immune infiltrating levels, MICAL1 expression was positively associated with CD8+/Treg cell infiltration levels. Specifically, bioinformatic analysis showed that MICAL1 expression had strong relationships with various T cell exhaustion markers.

CONCLUSIONS

MICAL1 expression may act as a prognostic biomarker for determining the prognosis in renal clear cell carcinoma and plays an important role in regulating tumor immune microenvironment and cell migratory capacity.

MICAL1 facilitates pancreatic cancer proliferation, migration, and invasion by activating WNT/β-catenin pathway

Background

MICAL1 is involved in the malignant processes of several types of cancer; however, the role of MICAL1 in pancreatic cancer (PC) has not been well-characterized. This study aimed to investigate the expression and function of MICAL1 in PC.

Methods

RT-qPCR and immunohistochemistry were used to detect MICAL1 expression in PC and adjacent nontumor tissues. Cell Counting Kit-8, EdU, clone formation, wound healing, and Transwell assays as well as animal models were used to investigate the effects of overexpression or inhibition of MICAL1 expression on the proliferation, invasion, and metastasis of PC cells. RNA-seq was used to explore the main pathway underlying the functions of MICAL1. Proteomics, mass spectrometry, and co-immunoprecipitation assays were used to investigate the interaction of proteins with MICAL1. Rescue experiments were conducted to validate these findings.

Results

Both MICAL1 mRNA and protein levels were upregulated in PC tissues compared with matched adjacent nontumor tissues. The expression level of MICAL1 was associated with the proliferative and metastatic status of PC. Repression of MICAL1 significantly inhibited PC cell growth, migration, and invasion in vitro and in vivo. RNA sequencing analysis indicated that MICAL1 was closely correlated with the WNT pathway. Overexpression of MICAL1 (1) promoted the phosphorylation of TBC1D1 at the Ser660 site, (2) facilitated the distribution of FZD7 on the cytomembrane, (3) inhibited the degradation of FZD7 in the lysosome, and (4) activated the WNT pathway.

Conclusions

MICAL1 was upregulated in PC and involved in stimulating the progression of PC cells by activating the WNT/β-catenin signaling pathway. Therefore, MICAL1 is a potential therapeutic target for PC.

MICAL2 contributes to gastric cancer cell migration via Cdc42-dependent activation of E-cadherin/β-catenin signaling pathway

Background

Gastric cancer is a common and lethal human malignancy worldwide and cancer cell metastasis is the leading cause of cancer-related mortality. MICAL2, a flavoprotein monooxygenase, is an important regulator of epithelial-to-mesenchymal transition. The aim of this study was to explore the effects of MICAL2 on gastric cancer cell migration and determine the underlying molecular mechanisms.

Methods

Cell migration was examined by wound healing and transwell assays. Changes in E-cadherin/β-catenin signaling were determined by qPCR and analysis of cytoplasmic and nuclear protein fractions. E-cadherin/β-catenin binding was determined by co-immunoprecipitation assays. Cdc42 activity was examined by pulldown assay.

Results

MICAL2 was highly expressed in gastric cancer tissues. The knockdown of MICAL2 significantly attenuated migratory ability and β-catenin nuclear translocation in gastric cancer cells while LiCl treatment, an inhibitor of GSK3β, reversed these MICAL2 knockdown-induced effects. Meanwhile, E-cadherin expression was markedly enhanced in MICAL2-depleted cells. MICAL2 knockdown led to a significant attenuation of E-cadherin ubiquitination and degradation in a Cdc42-dependent manner, then enhanced E-cadherin/β-catenin binding, and reduced β-catenin nuclear translocation.

Conclusions

Together, our results indicated that MICAL2 promotes E-cadherin ubiquitination and degradation, leading to enhanced β-catenin signaling via the disruption of the E-cadherin/β-catenin complex and, consequently, the promotion of gastric cell migration.

miR-4735-3p inhibits cell migration and invasion of gastric cancer by downregulating NEDD9

Gastric cancer (GC) comprises the 3rd cause of cancer-related death worldwide. Increased expression of neural precursor cell expressed, developmentally downregulated 9 (NEDD9) is commonly observed in GC, however, its underlying molecular mechanism in GC remains unknown. The potential interaction between miR-4735-3p and NEDD9 was predicted by TargetScan 7.1. Expression profiles of miR-4735-3p and NEDD9 were examined between GC tissues and normal tissues by reverse transcription-quantitative (RT-q) PCR. The relationship between miR-4735-3p and NEDD9 was validated by RT-qPCR, western blotting, dual luciferase reporter assay and RNA immunoprecipitation assay. Biological relationship between miR-4735-3p and NEDD9 was evidenced by the cell invasion and cell migration assays. NEDD9 level was negatively associated with miR-4735-3p level in GC tissues. miR-4735-3p suppressed NEDD9 levels in GC cells. NEDD9 was revealed to be a target gene of miR-4735-3p. miR-4735-3p overexpression suppressed cell migration and invasion of GC cells, which were antagonized by overexpression of NEDD9. Moreover, miR-4735-3p mimic decreased the levels of matrix metalloproteinases 2/9, increased the level of E-cadherin, which were reversed by overexpression of NEDD9. Collectively, the present study provided a potential mechanism for the tumor suppressor role of miR-4735-3p in GC by targeting NEDD9.

Oxidation and reduction of actin: Origin, impact in vitro and functional consequences in vivo

Actin is among the most abundant proteins in eukaryotic cells and assembles into dynamic filamentous networks regulated by many actin binding proteins. The actin cytoskeleton must be finely tuned, both in space and time, to fulfill key cellular functions such as cell division, cell shape changes, phagocytosis and cell migration. While actin oxidation by reactive oxygen species (ROS) at non-physiological levels are known for long to impact on actin polymerization and on the cellular actin cytoskeleton, growing evidence shows that direct and reversible oxidation/reduction of specific actin amino acids plays an important and physiological role in regulating the actin cytoskeleton. In this review, we describe which actin amino acid residues can be selectively oxidized and reduced in many different ways (e.g. disulfide bond formation, glutathionylation, carbonylation, nitration, nitrosylation and other oxidations), the cellular enzymes at the origin of these post-translational modifications, and the impact of actin redox modifications both in vitro and in vivo. We show that the regulated balance of oxidation and reduction of key actin amino acid residues contributes to the control of actin filament polymerization and disassembly at the subcellular scale and highlight how improper redox modifications of actin can lead to pathological conditions.

MICAL1 Monooxygenase in Autosomal Dominant Lateral Temporal Epilepsy: Role in Cytoskeletal Regulation and Relation to Cancer

Autosomal dominant lateral temporal epilepsy (ADLTE) is a genetic focal epilepsy associated with mutations in the LGI1, RELN, and MICAL1 genes. A previous study linking ADLTE with two MICAL1 mutations that resulted in the substitution of a highly conserved glycine residue for serine (G150S) or a frameshift mutation that swapped the last three C-terminal amino acids for 59 extra residues (A1065fs) concluded that the mutations increased enzymatic activity and promoted cell contraction. The roles of the Molecule Interacting with CasL 1 (MICAL1) protein in tightly regulated semaphorin signaling pathways suggest that activating MICAL1 mutations could result in defects in axonal guidance during neuronal development. Further studies would help to illuminate the causal relationships of these point mutations with ADLTE. In this review, we discuss the proposed pathogenesis caused by mutations in these three genes, with a particular emphasis on the G150S point mutation discovered in MICAL1. We also consider whether these types of activating MICAL1 mutations could be linked to cancer.

A novel bioavailable curcumin-galactomannan complex modulates the genes responsible for the development of chronic diseases in mice: A RNA sequence analysis

BACKGROUND

Chronic diseases or non-communicable diseases are a major burden worldwide due to the lack of highly efficacious treatment modalities and the serious side effects associated with the available therapies.

PURPOSE/STUDY DESIGN

A novel self-emulsifying formulation of curcumin with fenugreek galactomannan hydrogel scaffold as a water-dispersible non-covalent curcumin-galactomannan molecular complex (curcumagalactomannosides, CGM) has shown better bioavailability than curcumin and can be used for the prevention and treatment of chronic diseases. However, the exact potential of this formulation has not been studied, which would pave the way for its use for the prevention and treatment of multiple chronic diseases.

METHODS

The whole transcriptome analysis (RNAseq) was used to identify differentially expressed genes (DEGs) in the liver tissues of mice treated with LPS to investigate the potential of CGM on the prevention and treatment of chronic diseases. Expression analysis using DESeq2 package, GO, and pathway analysis of the differentially expressed transcripts was performed using UniProtKB and KEGG-KAAS server.

RESULTS

The results showed that 559 genes differentially expressed between the liver tissue of control mice and CGM treated mice (100 mg/kg b.wt. for 14 days), with adjusted p-value below 0.05, of which 318 genes were significantly upregulated and 241 were downregulated. Further analysis showed that 33 genes which were upregulated (log2FC > 8) in the disease conditions were significantly downregulated, and 32 genes which were downregulated (log2FC < -8) in the disease conditions were significantly upregulated after the treatment with CGM.

CONCLUSION

Overall, our study showed CGM has high potential in the prevention and treatment of multiple chronic diseases.

Identification of a Five-Gene Prognostic Signature Related to B Cells Infiltration in Pancreatic Adenocarcinoma

Background

Pancreatic adenocarcinoma (PAAD) is an extremely malignant cancer. Immunotherapy is a promising avenue to increase the survival time of patients with PAAD.

Methods

RNA sequencing and clinical data for PAAD were downloaded from the TCGA database. The ssGSEA method and weighted gene co-expression network analysis were used to calculate the relative abundance of tumor-infiltrating immune cells and identify the related modules. Least absolute shrinkage and selection operator (LASSO) and Cox regression analyses were used to construct a prognostic model. MCPcounter and EPIC were also used to assess immune cell components using gene expression profiles.

Results

The B cells closely related module was identified, and five genes, including ARID5A, CLEC2B, MICAL1, MZB1, and RAPGEF1, were ultimately selected to establish a prognostic signature to calculate the risk scores of PAAD patients. Kaplan–Meier curves showed worse survival in the high-risk patients (p < 0.05), and the area under the receiver operating characteristic (ROC) curves of risk score for 1-year and 3-year survival were 0.78 and 0.80, respectively, based on the training set. Similar results were verified using the validated and combined sets. Interestingly, the low-risk group presented significantly elevated immune and stromal scores, proportion of B cells, and associations between these five genes and B cells were identified using multiple methods including ssGSEA, MCPcounter, and EPIC.

Conclusion

This is the first attempt to study a B cells-related prognostic signature, which is instrumental in the exploration of novel prognostic biomarkers in PAAD.

KIF18B as a regulator in microtubule movement accelerates tumor progression and triggers poor outcome in lung adenocarcinoma

KIF18B is involved in several tumor progression and exerts critical effects on microtubule growth during mitosis, but its role in lung adenocarcinoma still remains rare. Hence, we attempted to explore the biological function of KIF18B in lung adenocarcinoma. We first analyzed the expressional pattern of KIF18B in lung adenocarcinoma, and detected the correlation between KIF18B expression and clinical characteristics in lung adenocarcinoma based on The Cancer Genome Atlas (TCGA) database and Oncomine dataset. Subsequently, cell counting kit-8 (CCK-8) assay, wound-healing analysis, and transwell method were performed to assess the effects of KIF18B in lung adenocarcinoma cells. Quantitative real-time reverse transcription-PCR (qRT-PCR) and western blotting were utilized to measure the mRNA and protein expression levels. Our results illustrated that KIF18B expression was significantly up-regulated in lung adenocarcinoma samples compared to normal specimens. High levels of KIF18B were associated with unfavorable prognosis of lung adenocarcinoma patients. Down-regulation of KIF18B in lung adenocarcinoma cells inhibited cell prolifartion, migration, and invasion. Western blot assay demonstrated that KIF18B knockdown markedly decreased Rac1-GTP expression, an important marker of migration and invasion in tumors. Moreover, the phosphorylation of AKT and mTOR expression levels were attenuated after KIF18B knockdown. Taken together, these data enhanced the point that KIF18B might promote lung adenocarcinoma cell proliferation, migration, and invasion by activating Rac1 and mediating the AKT/mTOR signaling pathway.

SOX2 promotes hypoxia-induced breast cancer cell migration by inducing NEDD9 expression and subsequent activation of Rac1/HIF-1α signaling

Background

Hypoxia, a major condition associated with the tumor microenvironment, stimulates the migration of cancer cells. SOX2 is a powerful transcription factor that shows higher expression in several cancers, however, its role in hypoxia-induced breast cancer cell migration remains largely elusive.

Methods

The human breast cancer cell lines MDA-MB-231 and MDA-MB-468 were cultured under hypoxic conditions. The cell migration rate was determined using the wound-healing and transwell assays. The protein levels of SOX2, NEDD9 and HIF-1α were evaluated via western blotting analysis. The NEDD9 mRNA levels were evaluated using qPCR. The activation of Rac1 was detected with the pulldown assay. The binding of SOX2 to the NEDD9 promoter was checked using the luciferase reporter assay. We also transfected breast cancer cells with specific siRNA for SOX2, NEDD9 or the Rac1 inactive mutant (T17 N) to investigate the role of SOX2, NEDD9 and Rac1 in the response to hypoxia.

Results

Hypoxia markedly increased SOX2 protein levels in a time-dependent manner. SiRNA-mediated disruption of SOX2 inhibited cell migration under hypoxic conditions. Hypoxia also significantly augmented the NEDD9 mRNA and protein levels. Interestingly, SOX2 is a positive transcriptional regulator of NEDD9. Knockdown of SOX2 inhibited hypoxia-induced NEDD9 mRNA and protein expressions. Furthermore, hypoxia-induced upregulation of Rac1 activity and HIF-1α expression was attenuated by SOX2 or NEDD9 silencing, and Rac1-T17 N abolished HIF-1α expression as well as cell migration in cells subjected to hypoxia.

Conclusions

Our results highlight the essential role of SOX2 in breast cancer cell motility. The upregulation of SOX2 under hypoxic conditions may facilitate NEDD9 transcription and expression, and subsequent activation of Rac1 and HIF-1α expression. This could accelerate breast cancer cell migration.