Overexpression of ADP-ribosylation factor 1 in human gastric carcinoma and its clinicopathological significance

Pan-cancer analysis of ARFs family and ARF5 promoted the progression of hepatocellular carcinoma

Background

ARF family proteins are a kind of small GTPases, which are involved in regulating a variety of basic functions of cells. In recent years, the role and molecular regulatory mechanisms of ARFs in tumor progression have received increasing attention, and research reports on most of their family members are increasing. However, research on the clinical and pathological relevance of ARF5 in cancer, especially in hepatocellular carcinoma, still needs to be improved.

Methods

RNA-seq data in the Cancer Genome Atlas (TCGA) and genome tissue expression (GTEx) databases were used to analyze the expression and pathological data of ARFs family in Pan-cancer. Kaplan-Meier and Cox regression were used for prognostic analysis of ARF5 and Pan-cancer. Combined with ImmuCellAI database and TIMER2 database, the relationship between ARF5 expression and immune cell tumor infiltration in hepatocellular carcinoma (HCC) was analyzed. WGCNA is used to construct the co-expression gene network related to ARF5 expression in HCC and screen important modules and central genes. GO and KEGG path enrichment analysis were carried out for the genes in the modules with clinical significance. GSEA analysis was performed to take into account the role of genes with small differences. Finally, ceRNA network analysis was used to explore the molecular mechanism of miRNAs and lncRNAs regulating ARF5 expression.

Results

ARFs family (ARF1, ARF3, ARF4, ARF5, ARF6) are generally highly expressed in Pan-cancer. ARF5 is significantly highly expressed in 29 cancers, and the high expression of ARF5 in HCC patients is significantly negatively correlated with OS, DFI, PFI and DSS, which may lead to cancer deterioration by participating in tumor immune infiltration of HCC. Through WGCNA analysis, the expression of ARF5 in HCC may be involved in many cellular processes that consume a lot of energy, such as ribosome formation, RNA and protein synthesis and lipids, as well as COVID-19, nonalcoholic fatty liver, neurodegenerative diseases and other disease pathways.

Conclusion

ARFs, especially ARF5, are overexpressed in many human tumors. This study shows for the first time that ARF5 is significantly correlated with the poor prognosis of HCC patients, which may play a role as an oncogene, suggesting that ARF5 has the potential as a biomarker for the diagnosis and treatment of HCC.

Identifying novel therapeutic targets in gastric cancer using genome-wide CRISPR-Cas9 screening

Genome-scale CRISPR-Cas9 screening technology is a powerful tool to systematically identify genes essential for cancer cell survival. Herein, TKOv3, a genome-scale CRISPR-Cas9 knock-out library, was screened in the gastric cancer (GC) cells, and relevant validation experiments were performed. We obtained 854 essential genes for the AGS cell line, and 184 were novel essential genes. After knocking down essential genes: SPC25, DHX37, ABCE1, SNRPB, TOP3A, RUVBL1, CIT, TACC3 and MTBP, cell viability and proliferation were significantly decreased. Then, we analysed the detected essential genes at different time points and proved more characteristic genes might appear with the extension of selection. After progressive selection using a series of open datasets, 41 essential genes were identified as potential drug targets. Among them, methyltransferase 1 (METTL1) was over expressed in GC tissues. High METTL1 expression was associated with poor prognosis among 3 of 6 GC cohorts. Furthermore, GC cells growth was significantly inhibited after the down-regulation of METTL1 in vitro and in vivo. Function analysis revealed that METTL1 might play a role in the cell cycle through AKT/STAT3 pathways. In conclusion, compared with existing genome-scale screenings, we obtained 184 novel essential genes. Among them, METTL1 was validated as a potential therapeutic target of GC.

Anticancer Effects of Helminthostachys zeylanica Ethyl acetate Extracts on Human Gastric Cancer Cells through Downregulation of the TNF-α-activated COX-2-cPLA2-PGE2 Pathway

Background: Gastric cancer (GC) is the second most prevalent cancer worldwide and the eighth most common cause of tumor-related death in Taiwan. Helminthostachys zeylanica, a flavonoid compound, has anti-inflammatory, immunomodulatory, and anticancer effects. We examined whether an extract of H. zeylanica (E1 and E2) has potential as a treatment for GC. Methods: We investigated the effects (pro-apoptosis, pro-autophagy, and antiproliferation ability) of H. zeylanica-E2 on cell viability in healthy gastric epithelial (GES-1) and GC cells (AGS and BGC823). H. zeylanica-E2 was toxic to GC cells but had little or no toxicity to normal cells. Results: In this study, H. zeylanica-E2 induced apoptosis through caspase 3/7, Bcl-2, Bax, cyclooxygenase-2 (COX-2), and cleaved poly (ADP-ribose) polymerase pathways in GC cells. In addition, it increased autophagy by stimulating autophagy-related protein (ATG)5, ATG7, LC3-I/LC3-II, and inhibiting COX-2 activity in GC cells. We also found that H. zeylanica-E2 exhibited antiproliferation ability through cell cycle arrest in G0/G1 and G2/M and suppressed the migration of GC cells. The anticancer effects of H. zeylanica-E2 in GC cells might be mediated partly through inhibition of tumor necrosis factor-α (TNF-α)-activated proinflammatory cytosolic phospholipase A2 (cPLA2)-COX-2-prostaglandin E₂ (PGE₂) pathway. Conclusions: Our results suggest that H. zeylanica-E2 has potential as a novel adjunctive agent for the treatment of GC.

Physiological and pathophysiological role of ion channels and transporters in the colorectum and colorectal cancer

The incidence of colorectal cancer has increased annually, and the pathogenesis of this disease requires further investigation. In normal colorectal tissues, ion channels and transporters maintain the water‐electrolyte balance and acid/base homeostasis. However, dysfunction of these ion channels and transporters leads to the development and progression of colorectal cancer. Therefore, this review focuses on the progress in understanding the roles of ion channels and transporters in the colorectum and in colorectal cancer, including aquaporins (AQPs), Cl⁻ channels, Cl⁻/HCO3‐ exchangers, Na⁺/HCO3‐ transporters and Na⁺/H⁺ exchangers. The goal of this review is to promote the identification of new targets for the treatment and prognosis of colorectal cancer.

The Role of ARF Family Proteins and Their Regulators and Effectors in Cancer Progression: A Therapeutic Perspective

The Adenosine diphosphate-Ribosylation Factor (ARF) family belongs to the RAS superfamily of small GTPases and is involved in a wide variety of physiological processes, such as cell proliferation, motility and differentiation by regulating membrane traffic and associating with the cytoskeleton. Like other members of the RAS superfamily, ARF family proteins are activated by Guanine nucleotide Exchange Factors (GEFs) and inactivated by GTPase-Activating Proteins (GAPs). When active, they bind effectors, which mediate downstream functions. Several studies have reported that cancer cells are able to subvert membrane traffic regulators to enhance migration and invasion. Indeed, members of the ARF family, including ARF-Like (ARL) proteins have been implicated in tumorigenesis and progression of several types of cancer. Here, we review the role of ARF family members, their GEFs/GAPs and effectors in tumorigenesis and cancer progression, highlighting the ones that can have a pro-oncogenic behavior or function as tumor suppressors. Moreover, we propose possible mechanisms and approaches to target these proteins, toward the development of novel therapeutic strategies to impair tumor progression.

Clinical relevance of ARF/ARL family genes and oncogenic function of ARL4C in endometrial cancer

Members of ADP-ribosylation factor (ARF)/ARF-like protein (ARL) family regulate malignant phenotype of cancer cells. The present study aims to investigate the clinical relevance of ARF/ARL family members in endometrial cancer. We report that several ARF/ARL family genes serve as prognostic biomarkers for endometrial cancer. Through a combination of TCGA database and immunohistochemistry analysis, we revealed that ARL4C, a member of ARL family, was overexpressed in endometrial cancer and might function as an oncogene in endometrial carcinogenesis. Gene set enrichment analysis (GSEA) and functional studies demonstrated that cell cycle and cell adhesion pathways were the potential mechanism of ARL4C in promoting endometrial cancer cell proliferation, migration and invasion. Moreover, we also observed the involvement of ARL4C in metformin-inhibited cellular proliferation of endometrial cancer. Collectively, knowledge of the expression and function of ARF/ARL family genes could provide a potential therapeutic strategy for endometrial cancer.

DEK Is a Potential Biomarker Associated with Malignant Phenotype in Gastric Cancer Tissues and Plasma

Gastric cancer (GC) is the second most widespread cause of cancer-related mortality worldwide. The discovery of novel biomarkers of oncoproteins can facilitate the development of therapeutic strategies for GC treatment. In this study, we identified novel biomarkers by integrating isobaric tags for relative and absolute quantitation (iTRAQ), a human plasma proteome database, and public Oncomine datasets to search for aberrantly expressed oncogene-associated proteins in GC tissues and plasma. One of the most significantly upregulated biomarkers, DEK, was selected and its expression validated. Our immunohistochemistry (IHC) (n = 92) and quantitative real-time polymerase chain reaction (qRT-PCR) (n = 72) analyses disclosed a marked increase in DEK expression in tumor tissue, compared with paired nontumor mucosa. Importantly, significantly higher preoperative plasma DEK levels were detected in GC patients than in healthy controls via enzyme-linked immunosorbent assay (ELISA). In clinicopathological analysis, higher expression of DEK in both tissue and plasma was significantly associated with advanced stage and poorer survival outcomes of GC patients. Data from receiver operating characteristic (ROC) curve analysis disclosed a better diagnostic accuracy of plasma DEK than carcinoembryonic antigen (CEA), carbohydrate antigen 19.9 (CA 19.9), and C-reactive protein (CRP), highlighting its potential as an effective plasma biomarker for GC. Plasma DEK is also more sensitive in tumor detection than the other three biomarkers. Knockdown of DEK resulted in inhibition of GC cell migration via a mechanism involving modulation of matrix metalloproteinase MMP-2/MMP-9 level and vice versa. Our results collectively support plasma DEK as a useful biomarker for making diagnosis and prognosis of GC patients.

Label-free proteomic analysis of silkworm midgut infected by Bombyx mori nuclear polyhedrosis virus

Bombyx mori nuclear polyhedrosis virus (BmNPV) is the most damaging virus for the production of silkworm cocoons. Antivirus research continues to be an important aspect of the silkworm industry. Two-dimensional electrophoresis and mass spectrometry have been applied for analyzing the midgut proteome of BmNPV-infected silkworms. In recent years, the isobaric tags for relative and absolute quantitation (iTRAQ) method has frequently been used when studying interaction between BmNPV and Bombyx mori, and useful information has been obtained. In this study, midgut proteins of BmNPV-infected silkworms were extracted from silkworm variety NIL·LVR with anti-BmNPV activity at 48 h, and proteome analysis was carried out using the label-free method. 2196 proteins were identified. Among them, there were 85 differentially expressed proteins, 45 upregulated proteins (immune-activated proteins), 28 downregulated proteins, and six proteins were specific for the BmNPV group and another six specific for control group. Many of the immune-activated proteins have been reported to have innate immune functions, and the downregulated proteins are involved in apoptosis or abnormal cell viability. In conclusion, this study provides evidence for host defense against BmNPV infection by both innate immunity and apoptosis, revealing the potential function of the midgut after oral infection of BmNPV in Bombyx mori. SIGNIFICANCE: Bombyx mori nuclear polyhedrosis virus (BmNPV) has a great impact on the sericulture industry. However, the mechanism of resistance to BmNPV has not been fully elucidated. The silkworm midgut is not only the major organ for food digestion and nutrient absorption but also an immune organ serving as the first line of defense against microbial invasion and proliferation. Here we combined label-free quantitative proteomic, bioinformatics, quantitative real-time PCR and SDS-PAGE analyses and found that BmNPV invasion causes complex protein alterations in the larval midgut of NIL·LVR with anti-BmNPV activity. The results showed that many upregulated differentially expressed proteins have been reported to have innate immune functions and the downregulation proteins are involved in apoptosis or abnormal cell viability. These findings provide evidence for host defense against BmNPV infection by both innate immunity and apoptosis, and reveals the potential function of the midgut after infection of BmNPV in Bombyx mori.

Functional disruption of the Golgi apparatus protein ARF1 sensitizes MDA-MB-231 breast cancer cells to the antitumor drugs Actinomycin D and Vinblastine through ERK and AKT signaling

Increasing evidence indicates that the Golgi apparatus plays active roles in cancer, but a comprehensive understanding of its functions in the oncogenic transformation has not yet emerged. At the same time, the Golgi is becoming well recognized as a hub that integrates its functions of protein and lipid biosynthesis to signal transduction for cell proliferation and migration in cancer cells. Nevertheless, the active function of the Golgi apparatus in cancer cells has not been fully evaluated as a target for combined treatment. Here, we analyzed the effect of perturbing the Golgi apparatus on the sensitivity of the MDA-MB-231 breast cancer cell line to the drugs Actinomycin D and Vinblastine. We disrupted the function of ARF1, a protein necessary for the homeostasis of the Golgi apparatus. We found that the expression of the ARF1-Q71L mutant increased the sensitivity of MDA-MB-231 cells to both Actinomycin D and Vinblastine, resulting in decreased cell proliferation and cell migration, as well as in increased apoptosis. Likewise, the combined treatment of cells with Actinomycin D or Vinblastine and Brefeldin A or Golgicide A, two disrupting agents of the ARF1 function, resulted in similar effects on cell proliferation, cell migration and apoptosis. Interestingly, each combined treatment had distinct effects on ERK1/2 and AKT signaling, as indicated by the decreased levels of either phospho-ERK1/2 or phospho-AKT. Our results suggest that disruption of Golgi function could be used as a strategy for the sensitization of cancer cells to chemotherapy.

MicroRNA-26b inhibits tumor metastasis by targeting the KPNA2/c-jun pathway in human gastric cancer

MicroRNAs (miRNA) play an important role in carcinogenesis. Previously, we identified miR-26b as a significantly downregulated miRNA in gastric cancer (GC) tissues (n = 106) based on differential quantitative RT-PCR (RT-qPCR) miRNA expression profiles. In the current study, we aimed to clarify the potential role of miR-26b and related target genes in GC progression. Downregulation of miR-26b was associated with advanced tumor-node-metastasis stage (TNM stage) and poor 5-year survival rate. Forced expression of miR-26b led to inhibition of GC cell migration and invasion in vitro and lung metastasis formation in vivo. Conversely, depletion of miR-26b had stimulatory effects. Additionally, miR-26b affected GC cell behavior through negative regulation of the metastasis promoter, karyopherin alpha 2 (KPNA2). Ectopic expression of miR-26b induced a reduction in KPNA2 protein levels, confirmed by luciferase assay data showing that miR-26b directly binds to the 3' untranslated regions (UTR) of KPNA2 mRNA. Furthermore, miR-26b and KPNA2 mRNA/protein expression patterns were inversely correlated in GC tissues. Cag A of Helicobacter pylori (Hp) enhanced miR-26b levels through regulation of the KPNA2/c-jun pathway. Taken together, our data indicate that miR-26b plays an anti-metastatic role and is downregulated in GC tissues via the KPNA2/c-jun pathway. Based on the study findings, we propose that miR-26b overexpression or KPNA2/c-jun suppression may have therapeutic potential in inhibiting GC metastasis.

ADP-ribosylation factor 1 expression regulates epithelial-mesenchymal transition and predicts poor clinical outcome in triple-negative breast cancer

Metastatic capacities are fundamental features of tumor malignancy. ADP-ribosylation factor (ARF) 1 has emerged as a key regulator of invasion in breast cancer cells. However, the importance of this GTPase, in vivo, remains to be demonstrated. We report that ARF1 is highly expressed in breast tumors of the most aggressive and advanced subtypes. Furthermore, we show that lowered expression of ARF1 impairs growth of primary tumors and inhibits lung metastasis in a murine xenograft model. To understand how ARF1 contributes to invasiveness, we used a poorly invasive breast cancer cell line, MCF7 (ER⁺), and examined the effects of overexpressing ARF1 to levels similar to that found in invasive cell lines. We demonstrate that ARF1 overexpression leads to the epithelial-mesenchymal transition (EMT). Mechanistically, ARF1 controls cell–cell adhesion through ß-catenin and E-cadherin, oncogenic Ras activation and expression of EMT inducers. We further show that ARF1 overexpression enhances invasion, proliferation and resistance to a chemotherapeutic agent. In vivo, ARF1 overexpressing MCF7 cells are able to form more metastases to the lung. Overall, our findings demonstrate that ARF1 is a molecular switch for cancer progression and thus suggest that limiting the expression/activation of this GTPase could help improve outcome for breast cancer patients.

Circulating microRNA-196a is an early gastric cancer biomarker

MicroRNA-196a (miRNA-196a) is associated with the development of gastric cancer and metastasis. Intestinal metaplasia and low- or high-grade dysplasia are considered to be precursors of intestinal type gastric cancer. Accordingly, we investigated the expression of plasma miRNA-196a as an early detection biomarker in precancerous gastric lesions and early cancer (pT1a/b), which is otherwise treated with endoscopic submucosal dissection. Our data showed that levels of circulating (plasma) miRNA-196a were higher in patients with precancerous lesions/early gastric adenocarcinoma than in healthy controls. The area under the receiver operating characteristic curve (AUC) for healthy controls vs. intestinal metaplasia was 0.9736; healthy controls vs. low-grade/high-grade dysplasia 0.9495; and healthy controls vs. early gastric cancer 0.9318. These results indicate that circulating miRNA-196a is a novel biomarker for detection of early gastric cancer and its precursor.

The Arf-GAP and protein scaffold Cat1/Git1 as a multifaceted regulator of cancer progression

Cool-associated tyrosine phosphorylated protein 1 (Cat1), also referred to as GPCR-kinase interacting protein 1 (Git1), is a ubiquitously expressed, multi-domain protein that is best known for regulating cell shape and migration. Cat1/Git1 functions as a GTPase activating protein (GAP) that inactivates certain members of the ADP-ribosylation factor (Arf) family of small GTPases. It is also a scaffold that brings together several signaling proteins at specific locations within the cell, ensuring their efficient activation. Here we will discuss what is known regarding the classical role of Cat1/Git1 in the regulation of cell morphology and migration, as well as highlight some more recent findings that suggest this interesting signaling/scaffolding protein may also contribute in unexpected ways to oncogenic transformation.

Association between epidermal growth factor receptor amplification and ADP-ribosylation factor 1 methylation in human glioblastoma

PURPOSE

Glioblastoma (GB) is the most frequent and most malignant primary brain tumor in adults. Previously, it has been found that both genetic and epigenetic factors may play critical roles in its etiology and prognosis. In addition, it has been found that the epidermal growth factor receptor gene (EGFR) is frequently over-expressed and amplified in primary GBs. Here, we assessed the promoter methylation status of 10 genes relevant to GB and explored associations between these findings and the EGFR gene amplification status.

METHODS

Tumor samples were obtained from 36 patients with primary GBs. In addition, 6 control specimens were included from patients who were operated for diseases other than brain tumors. The amplification status of the EGFR gene, and its deletion mutant EGFRvIII, were evaluated using FISH and MLPA, respectively. The IDH1/2 gene mutation status was verified using Sanger sequencing. A commercial DNA methylation kit was used to assess the promoter methylation status of 10 pre-selected genes. Metabolic profiles were measured using HR-MAS NMR spectroscopy. The EGFR and ARF1 mRNA expression levels were quantified using qRT-PCR.

RESULTS

Of the 10 genes analyzed, we found that only ARF1 promoter hypermethylation was significantly associated with EGFR gene amplification. ARF1 is a GTPase that is involved in vesicle trafficking and the Golgi apparatus. Subsequent tumor metabolism measurements revealed a positive association between EGFR amplification and different membrane precursors and methyl-donor metabolites. Finally, we found that EGFR gene amplifications were associated with distinct tumor infiltration patterns, thus representing a putative novel functional association between EGFR gene amplification and ARF1 gene promoter methylation in GB.

CONCLUSIONS

The results reported here provide a basis for a new hypotheses connecting EGFR gene amplification in GB cells with ARF1 gene promoter methylation, vesicle trafficking, membrane turnover and tumor metabolism. The mechanism(s) underlying these connections and their functional consequences remain to be established.

Arf proteins in cancer cell migration

Members of the ADP-ribosylation factor (Arf) family of small GTP-binding (G) proteins regulate several aspects of membrane trafficking, such as vesicle budding, tethering and cytoskeleton organization. Arf family members, including Arf-like (Arl) proteins have been implicated in several essential cellular functions, like cell spreading and migration. These functions are used by cancer cells to disseminate and invade the tissues surrounding the primary tumor, leading to the formation of metastases. Indeed, Arf and Arl proteins, as well as their guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs) have been found to be abnormally expressed in different cancer cell types and human cancers. Here, we review the current evidence supporting the involvement of Arf family proteins and their GEFs and GAPs in cancer progression, focusing on 3 different mechanisms: cell-cell adhesion, integrin internalization and recycling, and actin cytoskeleton remodeling.

Circulating microRNA-196a/b are novel biomarkers associated with metastatic gastric cancer

miR-196a and/or miR-196b, involved in cancer initiation and progression, are frequently upregulated in tumour tissues. However, the clinical significance of these microRNAs in gastric cancer (GC) remains to be clarified. In the current study, we investigated the potential utility of circulating miR-196a/b as novel biomarkers for early detection and/or metastatic prognosis of GC. The quantitative real time-polymerase chain reaction data revealed markedly higher pre-operative circulating miR-196a and miR-196b levels in GC patients than healthy controls. Receiver-operating characteristics curve analysis showed that circulating miR-196a, miR-196b and combined miR-196a and miR-196b (miR-196a/b) are more effective than carcinoembryonic antigen or carbohydrate antigen 19-9 alone in distinguishing GC patients from healthy controls, with higher sensitivity and specificity. Circulating miR-196a exhibited higher diagnostic capacity than combined miR-196a/b or miR-196b alone, highlighting its potential as an effective plasma biomarker for GC. In clinicopathological analysis, elevated circulating miR-196a/b levels were highly correlated with metastatic potential or more advanced stages of disease and poorer survival. In addition, the expression levels of circulating miR-196a/b were reduced after surgical resection in GC patients. Taken together, we propose that circulating miR-196a/b serve as a more sensitive and specific novel biomarker than carbohydrate antigen 19-9 for GC monitor, diagnosis and prognosis.

MicroRNA-27b suppresses tumor progression by regulating ARFGEF1 and focal adhesion signaling

The non‐receptor tyrosine kinase c‐Src is frequently activated during progression of colon cancers. In this study, we found that among the c‐Src‐regulated microRNAs (miRNAs), miR‐27b is also repressed by activation of K‐Ras/H‐Ras. Inhibitor studies suggested that the phosphatidylinositol 3‐kinase pathway is involved in the repression of miR‐27b. MicroRNA‐27b was repressed in various colon cancer cell lines and tumor tissues. Re‐expression of miR‐27b in human colon cancer HCT116 cells caused morphological changes and suppressed tumor growth, cell adhesion, and invasion. We also identified ARFGEF1 and paxillin as novel targets of miR‐27b, and found that miR‐27b‐mediated regulation of ARFGEF1 is crucial for controlling anchorage‐independent growth, and that of paxillin is important for controlling cell adhesion and invasion. Re‐expression of miR‐27b suppressed the activation of c‐Src induced by integrin‐mediated cell adhesion, suggesting that repression of miR‐27b may contribute to c‐Src activation in cancer cells. These findings show that miR‐27b functions as a tumor suppressor by controlling ARFGEF1 and the paxillin/c‐Src circuit at focal adhesions.

IGF-1 drives chromogranin A secretion via activation of Arf1 in human neuroendocrine tumour cells

Hypersecretion is the major symptom of functional neuroendocrine tumours. The mechanisms that contribute to this excessive secretion of hormones are still elusive. A key event in secretion is the exit of secretory products from the Golgi apparatus. ADP-ribosylation factor (Arf) GTPases are known to control vesicle budding and trafficking, and have a leading function in the regulation of formation of secretory granula at the Golgi. Here, we show that Arf1 is the predominant Arf protein family member expressed in the neuroendocrine pancreatic tumour cell lines BON and QGP-1. In BON cells Arf1 colocalizes with Golgi markers as well as chromogranin A, and shows significant basal activity. The inhibition of Arf1 activity or expression significantly impaired secretion of chromogranin A. Furthermore, we show that the insulin-like growth factor 1 (IGF-1), a major regulator of growth and secretion in BON cells, induces Arf1 activity. We found that activation of Arf1 upon IGF-1 receptor stimulation is mediated by MEK/ERK signalling pathway in BON and QGP-1 cells. Moreover, the activity of Arf1 in BON cells is mediated by autocrinely secreted IGF-1, and concomitantly, autocrine IGF1 secretion is maintained by Arf1 activity. In summary, our data indicate an important regulatory role for Arf1 at the Golgi in hypersecretion in neuroendocrine cancer cells.

Potential prognostic, diagnostic and therapeutic markers for human gastric cancer

The high incidence of gastric cancer (GC) and its consequent mortality rate severely threaten human health. GC is frequently not diagnosed until a relatively advanced stage. Surgery is the only potentially curative treatment. Thus, early screening and diagnosis are critical for improving prognoses in patients with GC. Gastroscopy with biopsy is an appropriate method capable of aiding the diagnosis of specific early GC tumor types; however, the stress caused by this method together with it being excessively expensive makes it difficult to use it as a routine method for screening for GC on a population basis. The currently used tumor marker assays for detecting GC are simple and rapid, but their use is limited by their low sensitivity and specificity. In recent years, several markers have been identified and tested for their clinical relevance in the management of GC. Here, we review the serum-based tumor markers for GC and their clinical significance, focusing on discoveries from microarray/proteomics research. We also review tissue-based GC tumor markers and their clinical application, focusing on discoveries from immunohistochemical research. This review provides a brief description of various tumor markers for the purposes of diagnosis, prognosis and therapeutics, and we include markers already in clinical practice and various forthcoming biomarkers.

MicroRNA-196a/-196b promote cell metastasis via negative regulation of radixin in human gastric cancer

MicroRNAs (miRNAs) play an important role to contribute carcinogenesis. The aim of the current study was to identify useful biomarkers from miRNAs. Differential miRNA profiles were analyzed using the miRNA qRT-PCR-based assay. Two of the most upregulated miRNAs were selected and validated. The miR-196a/-196b levels were significantly increased in gastric cancer (GC) tissues (n=109). Overexpression of miR-196a/-196b was significantly associated with tumor progression and poorer 5-year survival outcomes. Overexpression of miR-196a/-196b enhances GC cell migration and invasion. Further, radixin was identified as a target gene of miR-196a/-196b. Elevated miR-196a/-196b expression in GC cells led to reduced radixin protein levels and vice versa. Notably, an inverse correlation between miR-196a/-196b and radixin mRNA and protein expression was observed in GC tissues with in situ hybridization and immunohistochemistry analyses. Together, miR-196a/-196b inhibitory oligonucleotides or overexpression of the radixin may thus have therapeutic potential in suppressing GC metastasis.

ARF1 and SAR1 GTPases in endomembrane trafficking in plants

Small GTPases largely control membrane traffic, which is essential for the survival of all eukaryotes. Among the small GTP-binding proteins, ARF1 (ADP-ribosylation factor 1) and SAR1 (Secretion-Associated RAS super family 1) are commonly conserved among all eukaryotes with respect to both their functional and sequential characteristics. The ARF1 and SAR1 GTP-binding proteins are involved in the formation and budding of vesicles throughout plant endomembrane systems. ARF1 has been shown to play a critical role in COPI (Coat Protein Complex I)-mediated retrograde trafficking in eukaryotic systems, whereas SAR1 GTPases are involved in intracellular COPII-mediated protein trafficking from the ER to the Golgi apparatus. This review offers a summary of vesicular trafficking with an emphasis on the ARF1 and SAR1 expression patterns at early growth stages and in the de-etiolation process.