Gelsolin suppresses gastric cancer metastasis through inhibition of PKR-p38 signaling

Gelsolin, an Actin-Binding Protein: Bioinformatic Analysis and Functional Significance in Urothelial Bladder Carcinoma

The involvement of the actin-regulatory protein, gelsolin (GSN), in neoplastic transformation has been reported in different cancers including bladder cancer. However, the exact mechanism by which GSN influences bladder cancer development is not well understood. Here, we sought to reveal the functional significance of GSN in bladder cancer by undertaking a comprehensive bioinformatic analysis of TCGA datasets and through the assessment of multiple biological functions. GSN expression was knocked down in bladder cancer cell lines with two siRNA isoforms targeting GSN. Proliferation, migration, cell cycle and apoptosis assays were carried out. GSN expression, enrichment analysis, protein-protein interaction and immune infiltration analysis were verified through online TCGA tools. The data indicated that GSN expression is associated with bladder cancer proliferation, migration and enhanced cell apoptosis through regulation of NF-κB expression. GSN expression correlated with various inflammatory cells and may influence the immunity of the tumor microenvironment. Computational analysis identified several interacting partners which are associated with cancer progression and patient outcome. The present results demonstrate that GSN plays an important role in bladder cancer pathogenesis and may serve as a potential biomarker and therapeutic target for cancer therapy.

Role and therapeutic potential of gelsolin in atherosclerosis

Atherosclerosis is the major pathophysiological basis of a variety of cardiovascular diseases and has been recognized as a lipid-driven chronic inflammatory disease. Gelsolin (GSN) is a member of the GSN family. The main function of GSN is to cut and seal actin filaments to regulate the cytoskeleton and participate in a variety of biological functions, such as cell movement, morphological changes, metabolism, apoptosis and phagocytosis. Recently, more and more evidences have demonstrated that GSN is Closely related to atherosclerosis, involving lipid metabolism, inflammation, cell proliferation, migration and thrombosis. This article reviews the role of GSN in atherosclerosis from inflammation, apoptosis, angiogenesis and thrombosis.

Emerging roles of plasma gelsolin in tumorigenesis and modulating the tumor microenvironment

The protein expression of gelsolin, an actin scavenger controlling cytoskeletal remodeling, cell morphology, differentiation, movement, and apoptosis, has been found to be significantly decreased in several pathological conditions including neurodegenerative diseases, inflammatory disorders, and cancers. Its extracellular isoform, called plasma gelsolin (pGSN), is one of the most abundant plasma proteins in the circulation, and has emerged as a novel diagnostic biomarker for early disease detection. Current evidence reveals that gelsolin can function as either an oncoprotein or a tumor suppressor depending on the carcinoma type. Interestingly, recent studies have shown that pGSN is also involved in immunomodulation, revealing the multifunctional roles of pGSN in tumor progression. In this review, we discuss the current knowledge focusing on the roles of gelsolin in inflammation and wound healing, cancers, and tumor microenvironment. Future prospects of pGSN related studies and clinical application are also addressed.

Neutrophil Protein Kinase R Mediates Endothelial Adhesion and Migration by the Promotion of Neutrophil Actin Polymerization

Neutrophils protect against bacterial and fungal infections, but tight regulation of cell activation is essential for avoiding tissue damage in autoimmune disorders. Protein kinase R (PKR) is a serine/threonine kinase originally characterized by its role in the defense mechanisms against viral infection. Although PKR is involved in the signaling pathways of neurodegenerative diseases and metabolic disorders, its function in neutrophils is not well delineated. In this study, we demonstrate that human neutrophil PKR mediates adhesion to endothelial cells under physiological flow conditions but does not mediate rolling on those cells. Also, neutrophil PKR activation contributes to migration toward chemoattractants. Mechanistically, neutrophil PKR mediates the cell spreading and binding to ICAM-1 in static condition. Moreover, Ab microarray reveals that calcium/calmodulin-dependent protein kinase II is phosphorylated downstream of PKR and affects actin polymerization that is a cytoskeleton rearrangement indispensable for neutrophil migration induced by fMLF. In vivo, neutrophil recruitment into the dorsal air pouch of mice is reduced by PKR inhibitor treatment. Also, in mice with nephrotoxic serum nephritis, the compound treatment suppresses neutrophil accumulation in kidney glomerulus and subsequent development of albuminuria. Thus, in vascular inflammation, neutrophil PKR plays a critical role in the recruitment process, including endothelial adhesion and migration via leukocyte actin polymerization.

circFAM120B functions as a tumor suppressor in esophageal squamous cell carcinoma via the miR-661/PPM1L axis and the PKR/p38 MAPK/EMT pathway

Extensive changes of circRNA expression underscore their essential contributions to multiple hallmarks of cancers; however, their functions and mechanisms of action in esophageal squamous cell carcinoma (ESCC) remain undetermined. Here, we adopted a three-stage approach by first screening for significantly differentially expressed circRNAs in ESCC and performing an external validation study, followed by the functional analyses. The properties of circRNAs were evaluated using Sanger sequencing, RNase R digestion, actinomycin D treatment, subcellular localization analysis, and fluorescence in situ hybridization. Target transcripts were predicted using online tools and verified by dual-luciferase, RNA immunoprecipitation, qRT-PCR, and western blot. Biotin-labeled RNA-protein pull-down, mass spectrometry, and RNA immunoprecipitation were employed to identify proteins interacting with circRNAs. Gain- and loss-of-function experiments were performed to uncover the roles of circRNAs, their target genes, and binding proteins in the proliferation, metastasis, and invasion. We observed that circFAM120B (hsa_circ_0001666) was frequently downregulated in cancer tissues and patient plasma, and its expression level was related to overall survival in ESCC patients. Overexpression of circFAM120B inhibited the proliferation, metastasis, and invasion of ESCC while silencing it enhanced malignant phenotypes. Mechanistically, circFAM120B was predominantly located in the cytoplasm, guarantying its sponging for miR-661 to restore the expression of PPM1L, a tumor suppressor. We observed that circFAM120B could reduce the stability of RNA-dependent protein kinase (PKR) by promoting its ubiquitination-dependent degradation and subsequently regulating the p38 MAPK signaling pathway, resulting in the repression of EMTs in ESCC cells. Our findings suggest that circFAM120B is a promising biomarker of ESCC, which acts as a tumor suppressor via the circFAM120B/miR-661/PPM1L axis and PKR/p38 MAPK/EMT pathway, supporting its significance as a candidate therapeutic target.

Local ablation of gastric cancer by reconstituted apolipoprotein B lipoparticles carrying epigenetic drugs

Epigenetic inhibitors have shown anticancer effects. Combination chemotherapy with epigenetic inhibitors has shown high effectiveness in gastric cancer clinical trials, but severe side effect and local progression are the causes of treatment failure. Therefore, we sought to develop an acidity-sensitive drug delivery system to release drugs locally to diminish unfavorable outcome of gastric cancer. In this study, we showed that, as compared with single agents, combination treatment with the demethylating agent 5'-aza-2'-deoxycytidine and HDAC inhibitors Trichostatin A or LBH589 decreased cell survival, blocked cell cycle by reducing number of S-phase cells and expression of cyclins, increased cell apoptosis by inducing expression of Bim and cleaved Caspase 3, and reexpressed tumor suppressor genes more effectively in MGCC3I cells. As a carrier, reconstituted apolipoprotein B lipoparticles (rABLs) could release drugs in acidic environments. Orally administrated embedded drugs not only showed inhibitory effects on gastric tumor growth in a syngeneic orthotopic mouse model, but also reduced the hepatic and renal toxicity. In conclusion, we have established rABL-based nanoparticles embedded epigenetic inhibitors for local treatment of gastric cancer, which have good therapeutic effects but do not cause severe side effects.

Cytoskeletal Remodeling in Cancer

Simple Summary

Cell migration is an essential process from embryogenesis to cell death. This is tightly regulated by numerous proteins that help in proper functioning of the cell. In diseases like cancer, this process is deregulated and helps in the dissemination of tumor cells from the primary site to secondary sites initiating the process of metastasis. For metastasis to be efficient, cytoskeletal components like actin, myosin, and intermediate filaments and their associated proteins should co-ordinate in an orderly fashion leading to the formation of many cellular protrusions-like lamellipodia and filopodia and invadopodia. Knowledge of this process is the key to control metastasis of cancer cells that leads to death in 90% of the patients. The focus of this review is giving an overall understanding of these process, concentrating on the changes in protein association and regulation and how the tumor cells use it to their advantage. Since the expression of cytoskeletal proteins can be directly related to the degree of malignancy, knowledge about these proteins will provide powerful tools to improve both cancer prognosis and treatment.

Abstract

Successful metastasis depends on cell invasion, migration, host immune escape, extravasation, and angiogenesis. The process of cell invasion and migration relies on the dynamic changes taking place in the cytoskeletal components; actin, tubulin and intermediate filaments. This is possible due to the plasticity of the cytoskeleton and coordinated action of all the three, is crucial for the process of metastasis from the primary site. Changes in cellular architecture by internal clues will affect the cell functions leading to the formation of different protrusions like lamellipodia, filopodia, and invadopodia that help in cell migration eventually leading to metastasis, which is life threatening than the formation of neoplasms. Understanding the signaling mechanisms involved, will give a better insight of the changes during metastasis, which will eventually help targeting proteins for treatment resulting in reduced mortality and longer survival.

Differential expression of Scinderin and Gelsolin in gastric cancer and comparison with clinical and morphological characteristics

Gastric cancer is the first cause of cancer-related death in males and the second in female patients in Iran. Advanced cancer is usually associated with distant metastasis, which is uncontrollable. This study was conducted to compare the expression of Scinderin and Gelsolin genes between gastric cancer and adjacent normal tissue samples in Iranian patients in order to better understand the role of these genes in this disease and to assess them as potential gastric cancer diagnostic or prognostic biomarkers. This case-control study was conducted in 41 Iranian patients suffering from stage I to IV of Gastric Cancer diagnosed by pathologic and endoscopic tests. In this study, significant down-regulation of Gelsolin (p=0.001) and over-expression of Scinderin (p=0.001) were observed in tumor tissues compared to the adjacent normal tissues. The results of the present study showed decreased Gelsolin expression in patients above 40 years, while the relationship between Gelsolin expression and age was not significant; also, a significant increase was observed in Scinderin expression in patients above 40 years. Furthermore, Lymph node metastasis was observed in 59.52 % of the cases. The results showed that reduced Gelsolin and increased Scinderin expression were related to lymph node metastasis. Based on results, a significant association was observed between tumor size and Scinderin expression level. Furthermore, Gelsolin and Scinderin expressions were assessed in different grades and stages to determine the association of this gene with cancer progression. The result indicates significant alteration in Scinderin expression level of I and IV, II and IV, and III and IV stages. Although no significant association was observed between Scinderin expression level and GC grade, the mean Gelsolin expression showed a significant difference between grade II and III as well as grade I and IV. Based on our results, these genes would be potential biomarkers.

Gelsolin inhibits malignant phenotype of glioblastoma and is regulated by miR-654-5p and miR-450b-5p

We have previously shown that gelsolin (GSN) levels are significantly lower in the blood of patients with glioblastoma (GBM) than in healthy controls. Here, we analyzed the function of GSN in GBM and examined its clinical significance. Furthermore, microRNAs involved in GSN expression were also identified. The expression of GSN was determined using western blot analysis and found to be significantly lower in GBM samples than normal ones. Gelsolin was mainly localized in normal astrocytes, shown using immunohistochemistry and immunofluorescence. Higher expression of GSN was correlated with more prolonged progression‐free survival and overall survival. Gelsolin knockdown using siRNA and shRNA markedly accelerated cell proliferation and invasion in GBM in vitro and in vivo. The inactive form of glycogen synthase kinase‐3β was dephosphorylated by GSN knockdown. In GBM tissues, the expression of GSN and microRNA (miR)‐654‐5p and miR‐450b‐5p showed an inverse correlation. The miR‐654‐5p and miR‐450b‐5p inhibitors enhanced GSN expression, resulting in reduced proliferation and invasion. In conclusion, GSN, which inhibits cell proliferation and invasion, is suppressed by miR‐654‐5p and miR‐450b‐5p in GBM, suggesting that these miRNAs can be targets for treating GBM.

Pyrimethamine Elicits Antitumor Effects on Prostate Cancer by Inhibiting the p38-NF-κB Pathway

Since incurable castration-resistant prostate cancer (CRPC) inevitably develops following treatment with androgen deprivation therapy, there is an urgent need to devise new therapeutic strategies to treat this cancer. Pyrimethamine, an FDA-approved antimalarial drug, is known to exert an antitumor activity in various types of human cancer cells. However, whether pyrimethamine can inhibit prostate cancer is not well established. Hence, the present study aimed to characterize the mechanism of action of pyrimethamine on prostate cancer. We investigated the potential effect of pyrimethamine on cell proliferation, cell cycle, and apoptosis in metastatic DU145 and PC3 prostate cancer cells. We found that pyrimethamine inhibited cell proliferation, induced cell cycle arrest in the S phase, and promoted cell apoptosis of prostate cells in vitro; it also suppressed tumor growth in xenograft models. In addition, we observed that pyrimethamine suppressed prostate cancer growth by inhibiting the p38-NF-κB axis in vitro and in vivo. Thus, this study demonstrates that pyrimethamine is a novel p38 inhibitor that can exert antiproliferative and proapoptotic effects in prostate cancer by affecting cell cycle and intrinsic apoptotic signaling, thereby providing a novel strategy for using pyrimethamine in CRPC treatment.

UHRF1 silences gelsolin to inhibit cell death in early stage cervical cancer

Persistent infection with high-risk strains of human papillomavirus (HPV) is the primary cause of cervical cancer, the fourth most common cancer among women worldwide. Two oncoproteins encoded by the HPV genome, E6 and E7, are required for epigenetic modifications that promote cervical cancer development. We found that knockdown of HPV E6/E7 by siRNA reduced the levels of ubiquitin-like containing PHD and RING finger domain 1 (UHRF1) but increased the levels of gelsolin (GSN) in early stage cervical cancer cells. In addition, we found that UHRF1 levels were increased and GSN levels were decreased in early stage cervical cancer compared with those in normal cervical tissues, as shown by Western blot analysis, immunohistochemistry, and analysis of the Oncomine database. Moreover, knockdown of UHRF1 resulted in increased cell death in cervical cancer cell lines. Treatment of E6/E7-transformed HaCaT (HEK001) cells and HeLa cells with the DNA-hypomethylating agent 5-aza-2'-deoxycytidine and the histone deacetylase inhibitor Trichostatin A increased GSN expression levels. UHRF1 knockdown in HEK001 cells by siRNA or the UHRF1 antagonist thymoquinone increased GSN levels, induced cell cycle arrest and apoptosis, and increased the levels of p27 and cleaved PARP. Those results indicate that upregulation of UHRF1 by HPV E6/E7 causes GSN silencing and a reduction of cell death in early stage cervical cancer, suggesting that GSN might be a useful therapeutic target in early stage cervical cancer.

Gelsolin Promotes Cancer Progression by Regulating Epithelial-Mesenchymal Transition in Hepatocellular Carcinoma and Correlates with a Poor Prognosis

Gelsolin (GSN), a cytoskeletal protein, is frequently overexpressed in different cancers and promotes cell motility. The biological function of GSN in hepatocellular carcinoma (HCC) and its mechanism remain unclear. The expression of GSN was assessed in a cohort of 188 HCC patients. The effects of GSN on the migration and invasion of tumour cells were examined. Then, the role of GSN in tumour growth in vivo was determined by using a cancer metastasis assay. The possible mechanism by which GSN promotes HCC progression was explored. As a result, GSN was overexpressed in HCC tissues. High GSN expression was significantly correlated with late Edmondson grade, encapsulation, and multiple tumours. Patients with high GSN expression had worse overall survival (OS) and disease-free survival (DFS) than those with low GSN expression. GSN expression was identified as an independent risk factor in both OS (hazard risk (HR) = 1.620, 95% confidence interval (CI) = 1.105–2.373, P < 0.001) and DFS (HR = 1.744, 95% CI = 1.205–2.523, P=0.003). Moreover, GSN knockdown significantly inhibited the migration and invasion of HCC tumour cells, while GSN overexpression attenuated these effects by regulating epithelial-mesenchymal transition (EMT) In conclusion, GSN promotes cancer progression and is associated with a poor prognosis in HCC patients. GSN promotes HCC progression by regulating EMT.

Lower Expression of Gelsolin in Colon Cancer and Its Diagnostic Value in Colon Cancer Patients

Colon cancer is one of the most common malignancies causing the majority of cancer-related deaths. Gelsolin (GSN) has been found to be dysregulated in various cancers. However, the secreted GSN in colon cancer remains largely unknown. In the present study, we explored the expression profile of GSN in colon cancer tissues and the diagnostic value of serum GSN in colon cancer. In addition, the effects of secreted GSN in colon cancer cells were studied. We thus found that immunoreactive GSN levels were significantly lower in colon cancer tissues than those in non-tumor colon tissues. Functional studies demonstrated that secreted GSN could restrain cell invasion and migration in vitro. Mechanistically, dose dependent recombinant GSN down-regulated the expression of MMP2 and MMP9, which might restrain the process of cell invasion and migration. Furthermore, serum levels of GSN were significantly lower in colon cancer patients than those in healthy volunteers, and ROC curves showed serum level of GSN had a better diagnostic value for colon cancer (AUC=0.932) than the traditional tumor biomarker Carcinoembryonic Antigen (CEA) or Carbohydrate Antigen 19-9 (CA199). In conclusion, our results suggest that the secreted GSN restrains the invasion and migration of colon cancer cells. Meanwhile, the serum GSN may be a new biomarker for the diagnosis of colon cancer.

Plasma Gelsolin: Indicator of Inflammation and Its Potential as a Diagnostic Tool and Therapeutic Target

Gelsolin, an actin-depolymerizing protein expressed both in extracellular fluids and in the cytoplasm of a majority of human cells, has been recently implicated in a variety of both physiological and pathological processes. Its extracellular isoform, called plasma gelsolin (pGSN), is present in blood, cerebrospinal fluid, milk, urine, and other extracellular fluids. This isoform has been recognized as a potential biomarker of inflammatory-associated medical conditions, allowing for the prediction of illness severity, recovery, efficacy of treatment, and clinical outcome. A compelling number of animal studies also demonstrate a broad spectrum of beneficial effects mediated by gelsolin, suggesting therapeutic utility for extracellular recombinant gelsolin. In the review, we summarize the current data related to the potential of pGSN as an inflammatory predictor and therapeutic target, discuss gelsolin-mediated mechanisms of action, and highlight recent progress in the clinical use of pGSN.

A survey of metastasis suppressors in Metazoa

Metastasis suppressors are genes/proteins involved in regulation of one or more steps of the metastatic cascade while having little or no effect on tumor growth. The list of putative metastasis suppressors is constantly increasing although thorough understanding of their biochemical mechanism(s) and evolutionary history is still lacking. Little is known about tumor-related genes in invertebrates, especially non-bilaterians and unicellular relatives of animals. However, in the last few years we have been witnessing a growing interest in this subject since it has been shown that many disease-related genes are already present in simple non-bilateral animals and even in their unicellular relatives. Studying human diseases using simpler organisms that may better represent the ancestral conditions in which the specific disease-related genes appeared could provide better understanding of how those genes function. This review represents a compilation of published literature and our bioinformatics analysis to gain a general insight into the evolutionary history of metastasis-suppressor genes in animals (Metazoa). Our survey suggests that metastasis-suppressor genes emerged in three different periods in the evolution of Metazoa: before the origin of metazoans, with the emergence of first animals and at the origin of vertebrates.

Tumor-associated macrophages-derived exosomes promote the migration of gastric cancer cells by transfer of functional Apolipoprotein E

Tumor-associated macrophages (TAMs) are a major component of the tumor microenvironment and have been shown to contribute to tumor aggressiveness. However, the detailed mechanisms underlying the pro-metastatic effect of TAMs on gastric cancer are not clearly defined. Here, we show that TAMs are enriched in gastric cancer. TAMs are characterized by M2-polarized phenotype and promote migration of gastric cancer cells in vitro and in vivo. Furthermore, we find that M2-derived exosomes determine the TAMs-mediated pro-migratory activity. Using mass spectrometry, we identify that apolipoprotein E (ApoE) is highly specific and effective protein in M2 macrophages-derived exosomes. Moreover, TAMs are uniquely immune cells population expressed ApoE in gastric cancer microenvironment. However, exosomes derived from M2 macrophages of Apoe^−/− mice have no significant effect on the migration of gastric cancer cells in vitro and in vivo. Mechanistically, M2 macrophage-derived exosomes mediate an intercellular transfer of ApoE-activating PI3K-Akt signaling pathway in recipient gastric cancer cells to remodel the cytoskeleton-supporting migration. Collectively, our findings signify that the exosome-mediated transfer of functional ApoE protein from TAMs to the tumor cells promotes the migration of gastric cancer cells.

Kisspeptin inhibits cancer growth and metastasis via activation of EIF2AK2

Kisspeptin is a protein encoded by the KISS1 gene, which has been reported to suppress the metastatic capabilities of various types of cancer cells, through the activation of its G‑protein coupled receptor GPR54. However, the molecular mechanisms underlying the involvement of kisspeptin‑mediated signaling in the inhibition of cancer cell migration and invasion have yet to be elucidated. The present in vitro cell proliferation, migration and invasion assays and in vivo experimental metastasis studies demonstrated that kisspeptin‑induced eukaryotic translation initiation factor 2α kinase 2 (EIF2AK2) activation suppressed the metastatic capabilities of several types of cancer cells. Kisspeptin was revealed to inhibit the migratory and invasive abilities of highly metastatic breast SK‑BR‑3, prostatic PC‑3 and colorectal adenocarcinoma LoVo human cancer cell lines, whereas its inhibitory effects were abolished following the silencing of EIF2AK2 expression using RNA interference. Similarly, kisspeptin failed to inhibit the migration and invasion of mouse embryonic fibroblasts following the deletion of the EIF2AK2 gene. Furthermore, kisspeptin was demonstrated to activate Ras homolog gene family member A (RhoA)‑dependent signaling, and to phosphorylate EIF2AK2 via RhoA‑mediated pathways in various cancer cells. In addition, results obtained from nude mice bearing LoVo‑derived xenograft tumors revealed that kisspeptin inhibited tumor growth through an EIF2AK2‑dependent mechanism, and an in vivo metastasis assay identified kisspeptin‑activated EIF2AK2 signaling as critical for the suppression of distant metastasis. The present study concluded that kisspeptin represses cancer metastasis via EIF2AK2 signaling, thus clarifying the role of kisspeptin signaling in complicated cancer metastasis signaling network. Therefore, kisspeptin treatment may be a choice for blocking metastases.

Clinical and therapeutic potential of protein kinase PKR in cancer and metabolism

The protein kinase R (PKR, also called EIF2AK2) is an interferon-inducible double-stranded RNA protein kinase with multiple effects on cells that plays an active part in the cellular response to numerous types of stress. PKR has been extensively studied and documented for its relevance as an antiviral agent and a cell growth regulator. Recently, the role of PKR related to metabolism, inflammatory processes, cancer and neurodegenerative diseases has gained interest. In this review, we summarise and discuss the involvement of PKR in several cancer signalling pathways and the dual role that this kinase plays in cancer disease. We emphasise the importance of PKR as a molecular target for both conventional chemotherapeutics and emerging treatments based on novel drugs, and its potential as a biomarker and therapeutic target for several pathologies. Finally, we discuss the impact that the recent knowledge regarding PKR involvement in metabolism has in our understanding of the complex processes of cancer and metabolism pathologies, highlighting the translational research establishing the clinical and therapeutic potential of this pleiotropic kinase.