cAMP signaling increases histone deacetylase 8 expression via the Epac2-Rap1A-Akt pathway in H1299 lung cancer cells

TIPRL, a Potential Double-edge Molecule to be Targeted and Re-targeted Toward Cancer

The target of rapamycin (TOR) proteins exhibits phylogenetic conservation across various species, ranging from yeast to humans, and are classified as members of the phosphatidylinositol kinase (PIK)-related kinase family. Multiple serine/threonine (Ser/Thr) protein phosphatases (PP)2A, PP4, and PP6, have been recognized as constituents of the TOR signaling pathway in mammalian cells. The protein known as TOR signaling pathway regulator-like (TIPRL) functions as a regulatory agent by impeding the activity of the catalytic subunits of PP2A. Various cellular contexts have been postulated for TIPRL, encompassing the regulation of mechanistic target of rapamycin (mTOR) signaling, inhibition of apoptosis and biogenesis, and recycling of PP2A. According to reports, there has been an observed increase in TIPRL levels in several types of carcinomas, such as non-small-cell lung carcinoma (NSCLC) and hepatocellular carcinomas (HCC). This review aims to comprehensively examine the significance of the Tor pathway in regulating apoptosis and proliferation of cancer cells, with a specific focus on the role of TOR signaling and TIPRL in cancer.

Function of m5C RNA methyltransferase NOP2 in high-grade serous ovarian cancer

RNA methyltransferase nucleolar protein p120 (NOP2), commonly referred to as NOP2/Sun RNA methyltransferase family member 1 (NSUN1), is involved in cell proliferation and is highly expressed in various cancers. However, its role in high-grade serous ovarian cancer (HGSOC) remains unclear. Our study investigated the expression of NOP2 in HGSOC tissues and normal fimbria tissues, and found that NOP2 was significantly upregulated in HGSOC tissues. Our experiments showed that NOP2 overexpression promoted cell proliferation in vivo and in vitro and increased the migration and invasion ability of HGSOC cells in vitro. Furthermore, we identified Rap guanine nucleotide exchange factor 4 (RAPGEF4) as a potential downstream target of NOP2 in HGSOC. Finally, our findings suggest that the regulation of NOP2 and RAPGEF4 may depend on m5C methylation levels.

EPAC Regulates Melanoma Growth by Stimulating mTORC1 Signaling and Loss of EPAC Signaling Dependence Correlates with Melanoma Progression

Exchange proteins directly activated by cAMP (EPAC) belong to a family of RAP guanine nucleotide exchange factors (RAPGEF). EPAC1/2 (RAPGEF3/4) activates RAP1 and the alternative cAMP signaling pathway. We previously showed that the differential growth response of primary and metastatic melanoma cells to cAMP is mediated by EPAC. However, the mechanisms responsible for this differential response to EPAC signaling are not understood. In this study, we show that pharmacologic inhibition or siRNA-mediated knockdown of EPAC selectively inhibits the growth and survival of primary melanoma cells by downregulation of cell-cycle proteins and inhibiting the cell-cycle progression independent of ERK1/2 phosphorylation. EPAC inhibition results in upregulation of AKT phosphorylation but a downregulation of mTORC1 activity and its downstream effectors. We also show that EPAC regulates both glycolysis and oxidative phosphorylation, and production of mitochondrial reactive oxygen species, preferentially in primary melanoma cells. Employing a series of genetically matched primary and lymph node metastatic (LNM) melanoma cells, and distant organ metastatic melanoma cells, we show that the LNM and metastatic melanoma cells become progressively less responsive and refractory to EPAC inhibition suggesting loss of dependency on EPAC signaling correlates with melanoma progression. Analysis of The Cancer Genome Atlas dataset showed that lower RAPGEF3, RAPGEF4 mRNA expression in primary tumor is a predictor of better disease-free survival of patients diagnosed with primary melanoma suggesting that EPAC signaling facilitates tumor progression and EPAC is a useful prognostic marker. These data highlight EPAC signaling as a potential target for prevention of melanoma progression.

IMPLICATIONS

This study establishes loss of dependency on EPAC-mTORC1 signaling as hallmark of primary melanoma evolution and targeting this escape mechanism is a promising strategy for metastatic melanoma.

Research progress on the relationship between the TOR signaling pathway regulator, epigenetics, and tumor development

Almost all cellular activities depend on protein folding, signaling complex assembly/disassembly, and epigenetic regulation. One of the most important regulatory mechanisms responsible for controlling these cellular processes is dynamic protein phosphorylation/dephosphorylation. Alterations in phosphorylation networks have major consequences in the form of disorders, including cancer. Many signaling cascades, including the target of rapamycin (TOR) signaling, are important participants in the cell cycle, and dysregulation in their phosphorylation/dephosphorylation status has been linked to malignancies. As a TOR signaling regulator, protein phosphatase 2A (PP2A) is responsible for most of the phosphatase activities inside the cells. On the other hand, TOR signaling pathway regulator (TIPRL) is an essential PP2A inhibitory protein. Many other physiological roles have also been suggested for TIPRL, such as modulation of TOR pathways, apoptosis, and cell proliferation. It is also reported that TIPRL was increased in various carcinomas, including non-small-cell lung carcinoma (NSCLC) and hepatocellular carcinomas (HCC). Considering the function of PP2A as a tumor suppressor and also the effect of the TIPRL/PP2A axis on apoptosis and proliferation of cancer cells, this review aims to provide a complete view of the role of TIPRL in cancer development in addition to describing TIPRL/PP2A axis and its epigenetic regulation.

MiR-942-3p as a Potential Prognostic Marker of Gastric Cancer Associated with AR and MAPK/ERK Signaling Pathway

Gastric cancer is a common tumor with high morbidity and mortality. MicroRNA (miRNA) can regulate gene expression at the translation level and various tumorigenesis processes, playing an important role in tumor occurrence and prognosis. This study aims to screen miRNA associated with gastric cancer prognosis as biomarkers and explore the regulatory genes and related signaling pathways. In this work, R language was used for the standardization and differential analysis of miRNA and mRNA expression profiles. Samples were randomly divided into a testing group and a training group. Subsequently, we built the five miRNAs (has-miR-9-3p, has-miR-135b-3p, has-miR-143-5p, has-miR-942-3p, has-miR-196-3p) prognostic modules, verified and evaluated their prediction ability by the Cox regression analysis. They can be used as an independent factor in the prognosis of gastric cancer. By predicting and analyzing potential biological functions of the miRNA target genes, this study found that the AR gene was not only a hub gene in the PPI network, but also associated with excessive survival of patients. In conclusion, this study demonstrated that hsa-miR-942-3p could be a potential prognostic marker of gastric cancer associated with the AR and MAPK/ERK signaling pathways. The results of this study provide insights into the occurrence and development of gastric cancer.

A peptide translated from circPPP1R12A promotes the malignancy of non-small cell lung cancer cells through AKT signaling pathway

BACKGROUND

Recent literature have indicated that the malignancy of cancer cells is modulated by hsa_circ_0000423 (named circPPP1R12A) through the way of translating protein. Herein, we investigated the role and latent mechanisms of circPPP1R12A in Non-Small Cell Lung Cancer (NSCLC).

METHODS

CircPPP1R12A expression was measured by qRT-PCR. The malignancy of NSCLC was determined by CCK-8, TUNEL assay, Wound healing, Transwell and Western blotting assays. The underlying mechanisms of circPPP1R12A were confirmed by Western blotting and qRT-PCR assays.

RESULTS

CircPPP1R12A expression in NSCLC tissues was higher than that of neighboring normal tissues. CircPPP1R12A showed an upregulated expression in NSCLC cells. Upregulation of circPPP1R12A could promote the cell viability of NSCLC cells and reduce the apoptosis of NSCLC cells, while it could not promote cell invasion and migration. The reduction of cell viability and apoptosis was discovered in NSCLC cells with the silencing of circPPP1R12A, but circPPP1R12A knockdown does not inhibit cell invasion and migration. There was something interesting that circPPP1R12A encoding protein circPPP1R12A-73aa was found in NSCLC cells. Mutations in circPPP1R12a-73AA might disrupt the function of circPPP1ra-73AA in A549 and H1299 cells. Next, we found that circPPP1R12A caused the increased growth of NSCLC cells by activating AKT signaling pathway.

CONCLUSION

In summary, our study proved that NSCLC cell proliferation was promoted by circPPP1R12A-73aa translated from circPPP1R12A through the AKT pathway, which could throw some light on the understanding of the mechanism of NSCLC.

Epac: A Promising Therapeutic Target for Vascular Diseases: A Review

Vascular diseases affect the circulatory system and comprise most human diseases. They cause severe symptoms and affect the quality of life of patients. Recently, since their identification, exchange proteins directly activated by cAMP (Epac) have attracted increasing scientific interest, because of their role in cyclic adenosine monophosphate (cAMP) signaling, a well-known signal transduction pathway. The role of Epac in cardiovascular disease and cancer is extensively studied, whereas their role in kidney disease has not been comprehensively explored yet. In this study, we aimed to review recent studies on the regulatory effects of Epac on various vascular diseases, such as cardiovascular disease, cerebrovascular disease, and cancer. Accumulating evidence has shown that both Epac1 and Epac2 play important roles in vascular diseases under both physiological and pathological conditions. Additionally, there has been an increasing focus on Epac pharmacological modulators. Therefore, we speculated that Epac could serve as a novel therapeutic target for the treatment of vascular diseases.

cAMP Signaling in Cancer: A PKA-CREB and EPAC-Centric Approach

Cancer is one of the most common causes of death globally. Despite extensive research and considerable advances in cancer therapy, the fundamentals of the disease remain unclear. Understanding the key signaling mechanisms that cause cancer cell malignancy may help to uncover new pharmaco-targets. Cyclic adenosine monophosphate (cAMP) regulates various biological functions, including those in malignant cells. Understanding intracellular second messenger pathways is crucial for identifying downstream proteins involved in cancer growth and development. cAMP regulates cell signaling and a variety of physiological and pathological activities. There may be an impact on gene transcription from protein kinase A (PKA) as well as its downstream effectors, such as cAMP response element-binding protein (CREB). The position of CREB downstream of numerous growth signaling pathways implies its oncogenic potential in tumor cells. Tumor growth is associated with increased CREB expression and activation. PKA can be used as both an onco-drug target and a biomarker to find, identify, and stage tumors. Exploring cAMP effectors and their downstream pathways in cancer has become easier using exchange protein directly activated by cAMP (EPAC) modulators. This signaling system may inhibit or accelerate tumor growth depending on the tumor and its environment. As cAMP and its effectors are critical for cancer development, targeting them may be a useful cancer treatment strategy. Moreover, by reviewing the material from a distinct viewpoint, this review aims to give a knowledge of the impact of the cAMP signaling pathway and the related effectors on cancer incidence and development. These innovative insights seek to encourage the development of novel treatment techniques and new approaches.

Prognostic Implications and Immune Infiltration Characteristics of Chromosomal Instability-Related Dysregulated CeRNA in Lung Adenocarcinoma

An accumulating body of research indicates that long-noncoding RNAs (lncRNAs) regulate the target genes and act as competitive endogenous RNAs (ceRNAs) playing an indispensable role in lung adenocarcinoma (LUAD). LUAD is frequently accompanied by the feature of chromosomal instability (CIN); however, CIN-related ceRNAs have not been investigated yet. We systematically analyzed and integrated CIN-related dysregulated ceRNAs characteristics in LUAD samples for the first time. In TCGA LUAD cohort, CIN in tumor samples was significantly higher than that in those of adjacent, and patients with high CIN risk tended to have worse clinical outcomes. We constructed a double-weighted CIN-related dysregulated ceRNA network, in which edge weight and node weight represented the disorder extent of ceRNA and the correlation of RNA expression level and prognosis, respectively. After module mining and analysis, a potential prognostic biomarker composed of 12 RNAs (8 mRNAs and 4 lncRNAs) named CIN-related dysregulated ceRNAs (CRDC) was obtained. The CRDC risk score had a positive relation with clinical stage and CIN, and patients with high CRDC risk scores exhibited poor prognosis. Moreover, CRDC tended to be an independent risk factor with high robustness to overcome the effect of multicollinearity among other explanatory variables for disease-specific survival (DSS) in TCGA and two GEO cohorts. The result of functional analysis indicated that CRDC was involved in multiple cancer progresses, especially immune-related pathways. The patients with lower CRDC risk had higher B cell, T cell CD4+, T cell CD8+, neutrophil, macrophage, and myeloid dendritic cell infiltration than the patients with higher CRDC risk. Meanwhile, patients with lower CRDC risk could get more benefits from immunological therapy. The results suggested that the CRDC could be a potential prognostic biomarker and an immunotherapy predictor for lung adenocarcinoma.

The Role of Neuropeptide-Stimulated cAMP-EPACs Signalling in Cancer Cells

Neuropeptides are autocrine and paracrine signalling factors and mainly bind to G protein-coupled receptors (GPCRs) to trigger intracellular secondary messenger release including adenosine 3′, 5′-cyclic monophosphate (cAMP), thus modulating cancer progress in different kind of tumours. As one of the downstream effectors of cAMP, exchange proteins directly activated by cAMP (EPACs) play dual roles in cancer proliferation and metastasis. More evidence about the relationship between neuropeptides and EPAC pathways have been proposed for their potential role in cancer development; hence, this review focuses on the role of neuropeptide/GPCR system modulation of cAMP/EPACs pathways in cancers. The correlated downstream pathways between neuropeptides and EPACs in cancer cell proliferation, migration, and metastasis is discussed to glimmer the direction of future research.

Revealing potential immunotherapy targets through analysis of a ceRNA network in human colon adenocarcinoma

BACKGROUND

Microsatellite instability-high (MSI-H) is a special type of human colon adenocarcinoma (COAD) that responds well to immunotherapy. MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs), which are important members of competing endogenous RNAs (ceRNAs) networks, are involved in the tumorigenesis and development of MSI-H COAD. This study aimed to establish a ceRNA network for MSI in COAD to identify targets and prognostic markers that may explain the effects of immunotherapy.

METHODS

COAD sequencing data were extracted from The Cancer Genome Atlas (TCGA), after which differentially expressed miRNAs, lncRNAs, and mRNAs were determined according to microsatellite status. After building a network based on the ceRNA hypothesis, the relationships between microsatellite status and clinical features were explored. Biological processes in the Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were analyzed for specific miRNAs, lncRNAs, and mRNAs. Survival analysis was used to identify potential biomarkers.

RESULTS

Based on the inclusion criteria, a total of 363 COAD samples were obtained from TCGA. Strict screening criteria were used to identify differentially expressed RNAs in the MSI-H and microsatellite-stable groups, with 82 miRNAs, 1,280 lncRNAs, and 2121 mRNAs obtained (fold change >2, false discovery rate <0.01). Based on the RNA interaction mechanism, a miRNA-lncRNA-mRNA network was constructed, through which a subnetwork composed of 5 miRNAs was discovered. hsa-miR-31-5p, hsa-miR-302a-3p, hsa-miR-302b-3p, hsa-miR-302d-3p, hsa-miR-3619-5p and the RNAs interaction with them have the potential to become novel targets to change the effect of existing immunotherapy. GO and KEGG analyses showed that these differentially expressed miRNAs, lncRNAs, and mRNAs may play key roles in tumorigenesis, tumor development, and drug efficacy, with natural killer cells potentially becoming the next emerging targets for immunotherapy enhancement. Moreover, survival analysis identified 10 lncRNAs as potential survival markers.

CONCLUSIONS

This study identified novel immunotherapy targets and revealed potential biomarkers for COAD according to microsatellite status.

Milk Exosome-Derived MicroRNA-2478 Suppresses Melanogenesis through the Akt-GSK3β Pathway

Exosomes participate in intercellular communication by transferring molecules from donor to recipient cells. Exosomes are found in various body fluids, including blood, urine, cerebrospinal fluid and milk. Milk exosomes contain many endogenous microRNA molecules. MicroRNAs are small noncoding RNAs and have important roles in biological processes. The specific biological functions of milk exosomes are not well understood. In this study, we investigated the effects of milk exosomes on melanin production in melanoma cells and melanocytes. We found that milk exosomes decreased melanin contents, tyrosinase activity and the expression of melanogenesis-related genes in melanoma cells and melanocytes. Bovine-specific miR-2478 in exosomes inhibited melanin production. We found that Rap1a is a direct target gene of miR-2478 in melanoma cells and melanocytes. MiR-2478 overexpression decreased Rap1a expression, which led to downregulated melanin production and expression of melanogenesis-related genes. Inhibition of Rap1a expression decreased melanogenesis through the Akt-GSK3β signal pathway. These results support the role of miR-2478 derived from milk exosomes as a regulator of melanogenesis through direct targeting of Rap1a. These results show that milk exosomes could be useful cosmeceutical ingredients to improve whitening.

Integrated analysis of DNA methylation and mRNA expression profiles to identify key genes in head and neck squamous cell carcinoma

DNA methylation has been demonstrated to play significant roles in the etiology and pathogenesis of head and neck squamous cell carcinoma (HNSCC). In the present study, methylation microarray dataset (GSE87053) and gene expression microarray dataset (GSE23558) were downloaded from GEO database and analyzed through R language. A total of 255 hypermethylated-downregulated genes and 114 hypomethylated-upregulated genes were finally identified. Functional enrichment analyses were performed and a comprehensive protein–protein interaction (PPI) network was constructed. Subsequently, the top ten hub genes selected by Cytoscape software were subjected to further analyses. It was illustrated that the expression level of CSF2, CTLA4, ETS1, PIK3CD, and CFTR was intimately associated with HNSCC. Survival analysis suggested that CTLA4 and FGFR2 could serve as effective independent prognostic biomarkers for HNSCC patients. Overall, our study lay a groundwork for further investigation into the underlying molecular mechanisms in HNSCC carcinogenesis, providing potential biomarkers and therapeutic targets for HNSCC.

Hsa_circ_0010235 functions as an oncogenic drive in non-small cell lung cancer by modulating miR-433-3p/TIPRL axis

BACKGROUND

Non-small cell lung cancer (NSCLC) is a threat to human health. Circular RNAs (circRNAs) have been proved to function in NSCLC development. In this study, the role of circRNA hsa_circ_0010235 in NSCLC progression and the possible molecular mechanism were explored.

METHODS

Expression of hsa_circ_0010235, miRNA (miR)-433-3p and TOR signaling pathway regulator-like (TIPRL) was examined by quantitative real-time PCR (qRT-PCR). Cell viability and clonogenicity were detected by cell counting kit-8 (CCK-8) assay and colony formation assay, respectively. Flow cytometry was performed to monitor cell apoptosis and cell cycle distribution. Western blot assay was employed to evaluate the protein levels of TIPRL, light chain 3 (LC3)-II/I and p62. Cell metastasis was assessed by Transwell and wound healing assays. The targeted relationship between miR-433-3p and hsa_circ_0010235 or TIPRL was confirmed by dual-luciferase reporter and RNA immunoprecipitation (RIP) assays. Furthermore, the role of hsa_circ_0010235 in vivo was investigated by xenograft assay.

RESULTS

Hsa_circ_0010235 and TIPRL were highly expressed in NSCLC tissues and cells, while miR-433-3p was downregulated. Depletion of hsa_circ_0010235 or gain of miR-433-3p repressed proliferation and autophagy but promoted apoptosis in NSCLC cells. Hsa_circ_0010235 sponged miR-433-3p to upregulate TIPRL expression, so as to affect NSCLC development. Hsa_circ_0010235 knockdown also blocked tumor growth in vivo.

CONCLUSION

Hsa_circ_0010235 knockdown suppressed NSCLC progression by regulating miR-433-3p/TIPRL axis, affording a novel mechanism of NSCLC progression.

The Role of Epac in Cancer Progression

Cancer continues to be a prime contributor to global mortality. Despite tremendous research efforts and major advances in cancer therapy, much remains to be learned about the underlying molecular mechanisms of this debilitating disease. A better understanding of the key signaling events driving the malignant phenotype of cancer cells may help identify new pharmaco-targets. Cyclic adenosine 3',5'-monophosphate (cAMP) modulates a plethora of biological processes, including those that are characteristic of malignant cells. Over the years, most cAMP-mediated actions were attributed to the activity of its effector protein kinase A (PKA). However, studies have revealed an important role for the exchange protein activated by cAMP (Epac) as another effector mediating the actions of cAMP. In cancer, Epac appears to have a dual role in regulating cellular processes that are essential for carcinogenesis. In addition, the development of Epac modulators offered new routes to further explore the role of this cAMP effector and its downstream pathways in cancer. In this review, the potentials of Epac as an attractive target in the fight against cancer are depicted. Additionally, the role of Epac in cancer progression, namely its effect on cancer cell proliferation, migration/metastasis, and apoptosis, with the possible interaction of reactive oxygen species (ROS) in these phenomena, is discussed with emphasis on the underlying mechanisms and pathways.

Identification of PDE7B as a Potential Core Gene Involved in the Metastasis of Clear Cell Renal Cell Carcinoma

Background

Metastasis is the main cause of treatment failure in various cancer, including ccRCC. However, the key genes involved in ccRCC metastasis remain largely unknown.

Purpose

The identification of the aberrant gene expression patterns associated with metastatic traits is of great clinical significance. The aim of this study was to investigate the clinical significance and function of PDE7B in ccRCC.

Materials and Methods

Expression profiling data for patient-matched primary and metastatic ccRCC tumors were obtained from GEO Dataset. Limma package was used to identify differentially expressed genes (DEGs) between the metastatic and the primary groups. Gene Ontology, Kyoto Encyclopedia of Genes Genomes (KEGG), and PPI network analysis were used to study the interacting activities and the interconnection of the DEGs. CCK-8 assays and Transwell assays were performed to detect the proliferation and migration of renal cancer cells.

Results

We obtained 163 DEGs, including 132 that were upregulated and 31 that were downregulated in metastatic ccRCC tissues. Both Gene Ontology function and KEGG pathway analysis showed that DEGs were involved in extracellular matrix (ECM) organization and cell adhesion. After utilizing PPI network to explore the interconnection among the DEGs, 22 genes were selected as the hub genes. Subsequently, survival analysis revealed that seven hub genes (SFN, NKX2-1, HP, MAPT, EPHA4, KCNAB1, and PDE7B) were significantly associated with overall survival disease-specific survival, and progression-free interval in ccRCC. Moreover, the low expression of PDE7B was found in clinical ccRCC samples and correlated with TNM stage and histologic grade. We further showed that knockdown of PDE7B increased cell growth and migration of renal cancer cells.

Conclusion

Our results implicated that PDE7B may play a key role in the development of metastatic RCC.

Roles of hsa-miR-12462 and SLC9A1 in acute myeloid leukemia

MicroRNAs (miRNAs) play important roles in cell proliferation, differentiation, and survival and may be useful for acute myeloid leukemia (AML) diagnosis and prognosis. In this study, we defined a novel miRNA, hsa-miR-12462, through small RNA sequencing of the bone marrow (BM) cells from 128 AML patients. Overexpression of hsa-miR-12462 in AML cells (U937 and HL-60) significantly decreased their growth rate when compared with those of the wild-type and MOCK controls. In a xenograft mouse model, tumor weight and size in the mice bearing the U937 cells with hsa-miR-12462 overexpression were significantly reduced when compared with those bearing the mock cells. The AML cells overexpressing hsa-miR-12462 had increased sensitivity to cytarabine chemotherapy. Combining the data from the MiRDB, an online microRNA database (http://mirdb.org), with the RNA-sequencing results, SLC9A1 was predicted to be one of the targets of hsa-miR-12462. hsa-miR-12462 was further confirmed to bind exclusively to the 3′UTR of SLC9A1 in U937 cells, leading to downregulation of SLC9A1. In summary, a higher level of hsa-miR-12462 in AML cells is associated with increased sensitivity to cytarabine chemotherapy via downregulation of SLC9A1.

Polyphenolic Composition and Anti-Melanoma Activity of White Forsythia (Abeliophyllum distichum Nakai) Organ Extracts

Abeliophyllum distichum Nakai, commonly called white forsythia, is a monotypic genus endemic to Korea. Although A. distichum is mainly used as an ornamental plant because of its horticultural value, recent studies have demonstrated its bioactivities, including antioxidant and anti-inflammatory activities, prompting us to investigate the potential anticancer effect of A. distichum organ extracts (leaves, fruit, and branches) against human melanoma SK-MEL-2 cells. The methanol extract of A. distichum leaves (AL) exhibited dose- and time-dependent cytotoxicities against SK-MEL-2 cells but not against HDFa human dermal fibroblasts. Based on high-performance liquid chromatography analysis, we identified 18 polyphenolic compounds from A. distichum organ extracts and suggest that differences in anticancer activity between organ extracts should be caused by different compositions of polyphenolic compounds. Additionally, the Annexin V/propidium iodide staining assay and analysis of caspase activity and expression indicated that AL induced cell death, including early and late apoptosis, as well as necrosis, by inducing the extrinsic pathway. Furthermore, we analyzed the differentially expressed genes between mock- and AL-treated cells using RNA-seq technology, suggesting that the anti-melanoma action of AL is mediated by down-regulation of the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway. Taken together, these results shed light on the potential use of A. distichum as a green resource with potent anti-melanoma activity.

Aquaporin 5 promotes tumor migration and angiogenesis in non-small cell lung cancer cell line H1299

Non-small cell lung cancer (NSCLC) constitutes the majority of all lung-cancer cases. Aquaporin 5 (AQP5) may be involved in NSCLC by promoting lung-cancer initiation and progression. The present study aimed to determine the role of AQP5 in migration and angiogenesis using NSCLC cells and HUVECs. AQPs 1, 3, 4, 5, 8 and 9 were screened in the NSCLC cell line H1299, and the present results showed that AQP5 mRNA was upregulated compared with the other AQP genes. At the protein level, AQP5 was significantly increased in H1299 cells compared with 16HBE cells. AQP5 knockdown in H1299 cells significantly decreased cell migration compared with untransfected cells, as demonstrated by both Transwell and wound closure assays. The present study further investigated H1299 ability to promote HUVEC vascularisation. The supernatants of both transfected and untransfected H1299 cells were used as conditioned medium for HUVECs, and tube formation was measured. The supernatant of AQP5-downregulated cells exhibited significantly low tube formation potential compared with untransfected cells. Similarly, vascular endothelial growth factor was significantly increased in control cells (si-NC) compared with cells transfected with small interfering RNA targeting AQP5. The present study found that AQP5 downregulation significantly decreased the phosphorylation level of epidermal growth factor receptor and the activity of the ERK1/2 pathway. In summary, the present study suggested that AQP5 influenced migration and angiogenesis in NSCLCs in vitro and may potentially exhibit similar in vivo effects.

Knockdown of TOR signaling pathway regulator suppresses cell migration and invasion in non-small cell lung cancer via the regulation of epithelial-to-mesenchymal transition

Non-small cell lung cancer (NSCLC) is one of the most common cancer types worldwide. Previous studies have indicated that TOR signaling pathway regulator (TIPRL) is involved in the progression of NSCLC. However, the underlying mechanisms of the role of TIPRL in regulating NSCLC metastasis have remained largely elusive. In the present study, the expression pattern of TIPRL in NSCLC was analyzed using The Cancer Genome Atlas (TCGA) dataset. Furthermore, Kaplan-Meier curve analysis was performed to evaluate the prognostic value of TIPRL in NSCLC, using the Kaplan-Meier Plotter and TCGA datasets. Loss-of-function assays were performed to determine the effects of TIPRL on cell migration and invasion. The results suggested that TIPRL was upregulated in NSCLC and positively associated with an advanced Tumor-Node-Metastasis stage. A higher expression level of TIPRL was associated with shorter overall and disease-free survival times in patients with NSCLC. To the best of our knowledge, the present study was the first to report that TIPRL acts as a metastasis promoter in NSCLC. Silencing of TIPRL suppressed A549 cell migration and invasion. Mechanistically, the present study indicated that TIPRL knockdown significantly promoted epithelial-cadherin expression, whereas it suppressed twist and vimentin expression in A549 cells. In conclusion, the present analysis suggested that TIPRL may serve as a biomarker for the prognosis of NSCLC and as a future target for its treatment.

Targeting Cyclic AMP Signalling in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a major healthcare problem worldwide, representing one of the leading causes of cancer mortality. Since there are currently no predictive biomarkers for early stage diagnosis, HCC is detected only in advanced stages and most patients die within one year, as radical tumour resection is generally performed late during the disease. The development of alternative therapeutic approaches to HCC remains one of the most challenging areas of cancer. This review focuses on the relevance of cAMP signalling in the development of hepatocellular carcinoma and identifies the modulation of this second messenger as a new strategy for the control of tumour growth. In addition, because the cAMP pathway is controlled by phosphodiesterases (PDEs), targeting these enzymes using PDE inhibitors is becoming an attractive and promising tool for the control of HCC. Among them, based on current preclinical and clinical findings, PDE4-specific inhibitors remarkably demonstrate therapeutic potential in the management of cancer outcomes, especially as adjuvants to standard therapies. However, more preclinical studies are warranted to ascertain their efficacy during the different stages of hepatocyte transformation and in the treatment of established HCC.

Identifying candidate diagnostic markers for early stage of non-small cell lung cancer

We performed a series of bioinformatics analysis on a set of important gene expression data with 76 samples in early stage of non-small cell lung cancer, including 40 adenocarcinoma samples, 16 squamous cell carcinoma samples and 20 normal samples. In order to identify the specific markers for diagnosis, we compared the two subtypes with the normal samples respectively to determine the gene expression characteristics. Through the multi-dimensional scaling classification, we found that the samples were clustered well according to the disease cases. Based on the classification results and using empirical Bayes moderation and treat method, 486 important genes associated with the disease were identified. We constructed gene functions and gene pathways to verify our result and explain the pathogenicity factor and process. We generated a protein-protein interaction network based on the mutual interaction between the selected genes and found that the top thirteen hub genes were highly associated with lung cancer or some other cancers including five newly found genes through our method. The results of this study indicated that contrast on the gene expression between different subtypes and normal samples provides important information for the detection of non-small cell lung cancer and helps exploration of the disease pathogenesis.

A Five-microRNA Signature as Prognostic Biomarker in Colorectal Cancer by Bioinformatics Analysis

Mounting evidence has demonstrated that a lot of miRNAs are overexpressed or downregulated in colorectal cancer (CRC) tissues and play a crucial role in tumorigenesis, invasion, and migration. The aim of our study was to screen new biomarkers related to CRC prognosis by bioinformatics analysis. By using the R language edgeR package for the differential analysis and standardization of miRNA expression profiles from The Cancer Genome Atlas (TCGA), 502 differentially expressed miRNAs (343 up-regulated, 159 down-regulated) were screened based on the cut-off criteria of p < 0.05 and |log2FC|>1, then all the patients (421) with differentially expressed miRNAs and complete survival time, status were then randomly divided into train group (212) and the test group (209). Eight miRNAs with p < 0.005 were revealed in univariate cox regression analysis of train group, then stepwise multivariate cox regression was applied for constituting a five-miRNA (hsa-miR-5091, hsa-miR-10b-3p, hsa-miR-9-5p, hsa-miR-187-3p, hsa-miR-32-5p) signature prognostic biomarkers with obviously different overall survival. Test group and entire group shown the same results utilizing the same prescient miRNA signature. The area under curve (AUC) of receiver operating characteristic (ROC) curve for predicting 5 years survival in train group, test group, and whole cohort were 0.79, 0.679, and 0.744, respectively, which demonstrated better predictive power of prognostic model. Furthermore, Univariate cox regression and multivariate cox regression considering other clinical factors displayed that the five-miRNA signature could serve as an independent prognostic factor. In order to predict the potential biological functions of five-miRNA signature, target genes of these five miRNAs were analyzed by Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway and Gene Ontology (GO) enrichment analysis. The top 10 hub genes (ESR1, ADCY9, MEF2C, NRXN1, ADCY5, FGF2, KITLG, GATA1, GRIA1, KAT2B) of target genes in protein protein interaction (PPI) network were screened by string database and Cytoscape 3.6.1 (plug-in cytoHubba). In addition, 19 of target genes were associated with survival prognosis. Taken together, the current study showed the model of five-miRNA signature could efficiently function as a novel and independent prognosis biomarker and therapeutic target for CRC patients.

Proteome and phosphoproteome reveal mechanisms of action of atorvastatin against esophageal squamous cell carcinoma

Statins comprise a class of prescription drugs used for reducing cholesterol. Evidence has also showed that statins could reduce cancer incidence. However, the anti-tumor mechanism of statins has not been fully defined. Here, we found that atorvastatin inhibited proliferation of esophageal squamous cell carcinoma (ESCC) cells. The underlying mechanisms were explored by mass spectrometry. The proteome data revealed that atorvastatin inhibited the cAMP and Rap1 signal pathways, except for Ras signal pathway. Interestingly, phosphoproteome profiles suggested that ERK^T185/Y187, CDK1^T14, and BRAC1^S1189 phosphorylation–mediated Th17 cell differentiation, Gap junction and the Platinum drug resistance pathway were down-regulated after atorvastatin treatment. The phosphorylation levels of ERK^T185/Y187, CDK1^T14 and BRAC1^S1189 were confirmed by western blotting in KYSE150 cells. More importantly, atorvastatin suppresses ESCC tumor growth in PDX models. The molecular changes in tumor tissues were confirmed by immunohistochemistry. In conclusion, deep-proteome and phosphoproteome analysis reveal a comprehensive mechanism that contributes to atorvastatin’s anti-tumor effect.

Rap1A promotes esophageal squamous cell carcinoma metastasis through the AKT signaling pathway

Ras‑associated protein 1A (Rap1A) is a member of the Ras subfamily of small GTP‑binding proteins and is found to promote metastasis in several types of cancer. However, the functional role and molecular mechanism of action in Rap1A in esophageal squamous cell carcinoma (ESCC) is not fully understood. In the present study, Rap1A was found to be upregulated in ESCC tissues and its expression was correlated with cancer stage. Functional studies revealed that Rap1A could promote ESCC metastasis by stimulating cell migration and invasion in vivo and in vitro. Further study indicated that the transcriptional factor SP1 increased Rap1A expression via promoter binding and transcription activation. Furthermore, Rap1A promoted epithelial‑to‑mesenchymal transition, possibly through the AKT signaling pathway. Hence, the findings of the present study indicated that Rap1A may be a potential prognostic marker or therapeutic target for ESCC.

Combination of Gentiana rhodantha and Gerbera anandria in the BL02 formula as therapeutics to non-small cell lung carcinoma acting via Rap1/cdc42 signaling: A transcriptomics/ bio-informatics biological validation approach

BACKGROUND

Non-small cell lung cancer (NSCLC) ranks the most commonly diagnosed and highest mortality-leading cancer worldwide despite a variety of treatment strategies are available. The highly heterogeneous and aggressive property of NSCLC as well as its poor prognosis indicates the need for novel therapeutic targets identification. The objective of this study is to identify potential targets from the adjuvant herbal formula BL02 using a combined approach of high throughput transcriptomics and network pharmacology.

METHODS

The quality and stability of BL02 were assessed by UHPLC analysis. The inhibitory effect of BL02 on NSCLC was measured by in vivo orthotopic intrathoracic mouse model and in vitro cellular models. EGFR-mutant HCC827 and wild type A549 cell lines were employed. Transcriptomics analysis was introduced to profile the gene expression of NSCLC cells treated with BL02; Network pharmacology and molecular docking analyses predicted the interaction of compounds and NSCLC targets. Immuno-blotting and pull-down assays verified the putative targets.

RESULTS

The UHPLC analysis revealed that BL02 was relatively stable between batches of production and for 24 months of storage. Orally administration of BL02 was safe and effective to inhibit pulmonary NSCLC growth in mice implanted with A549 and HCC827-generated tumors. BL02 exhibited relatively low cytotoxicity to NSCLC cells in vitro, but potently suppressed NSCLC cell motility. The transcriptomic analysis illustrated that EGFR and cellular adhesion-related signaling is involved in BL02 action. Further bioinformatics analysis validated BL02 activity is mediated by cdc42-regulated signaling. BL02 depolymerized the actin cytoskeleton through suppressing cdc42 and deactivating its upstream molecule Rap1. These effects may be primarily mediated by the direct binding of 5-methylcoumarin-4-cellobioside and mangiferin from BL02 to Rap1 protein.

CONCLUSION

Our study proposes an integration model of experimental, transcriptomic and bioinformatics analyses in the identification of novel therapeutic target of NSCLC from an adjuvant herbal formula BL02. Our findings revealed that inhibition of Rap1/cdc42 signaling by active compounds 5-methylcoumarin-4-cellobioside and mangiferin from BL02 might be potentially effective therapy for NSCLC.

Prognostic value of genome-wide DNA methylation patterns in noncoding miRNAs and lncRNAs in uveal melanomas

Background: Uveal melanomas are the most common primary intraocular malignant tumors in adults, associated with a high metastasis rate and a low 5-year survival rate. It is a clinic urgency and importance to identify prognostic factors for UVMs.

Results: 55 aberrantly methylated sites of miRNAs and 47 aberrantly methylated sites of lncRNAs were observed between Alive < 2 years group and Alive > 2 years group of UVMs. Two prognostic classifiers were generated. For 13- miRNAs-CpG-classifier, the AUC were 0.958, 0.848 and 0.824 at 1 year, 2 years and 3 years, respectively. For 9- lncRNAs-CpG-classifier, the AUC were 0.943, 0.869 and 0.866 at 1 year, 2 years and 3 years, respectively.

Conclusion: The correlation between genome-wide DNA methylation patterns of miRNAs and lncRNAs and the overall survival in UVMs were identified in this study. This novel finding shed new light on developing biomarkers of prognosis for UVMs.

Methods: DNA methylation profiles of noncoding miRNAs and lncRNAs for UVMs were accessed from The Cancer Genome Atlas. Then the prognostic value was analyzed by least absolute shrinkage and selection operator method Cox regression and tested by Time-dependent Receiver Operating Characteristic curve.

Scutellaria Flavonoids Effectively Inhibit the Malignant Phenotypes of Non-small Cell Lung Cancer in an Id1-dependent Manner

Non-small cell lung cancer (NSCLC) is the leading cause of cancer death in the world. Inhibitor of differentiation 1 (Id1) is overexpressed in NSCLC and involved in promoting its progression and metastasis. Identifying natural compounds targeting Id1 may have utility in NSCLC treatment. Here, we sought to determine whether the anti-tumor activities of Scutellaria flavonoids (SFs) were related to Id1. We reported that three SFs (baicalin, baicalein and wogonin) exhibited strong antitumor activity in NSCLC cells in vitro and in vivo. Id1 played a pivotal role on blockage of migration and invasion by SFs. Abrogation of invasion and migration mediated by baicalin, baicalein and wogonin were totally abolished by ectopic overexpression of Id1. Mechanistically, baicalin, baicalein and wogonin activated Rap1-GTP binding and dephosphorylated Akt and Src by suppressing a7nAChR, consequently triggering inhibition of Id1. Then attenuation of its downstream mediators, VEGF-A, N-cadherin, vimentin, combined with augment of E-cadherin led to the blockage of proliferation, EMT and angiogenesis of NSCLC. Overall, our data shed light on heretofore-undescribed role of SFs as modulators of Id1, which may be a useful strategy in the treatment of NSCLC.

Gene expression profile analysis of ENO1 knockdown in gastric cancer cell line MGC-803

Gastric cancer (GC) is the third leading cause of cancer-associated mortality. In a previous study, we identified that α-enolase (ENO1) promoted cell migration in GC, but the underlying molecular mechanisms remain to be fully elucidated. In the present study, small interfering RNAs were identified to interfere with ENO1 expression. The cDNA expression profiling was performed using an Affymetrix mRNA array platform to identify genes that may be associated with ENO1 in human GC cell line MGC-803. The differentially expressed genes (DEGs) were identified using the reverse transcription-quantitative polymerase chain reaction, followed by a series of bioinformatic analyses. As a result, there were 448 DEGs, among which 183 (40.85%) were downregulated. The most significant functional terms for the DEGs were the nuclear lumen for cell components (P=2.83×10⁻⁴), transcription for biological processes (P=3.7×10⁻⁷) and transcription factor activity for molecular functions (P=1.16×10⁴). In total, six significant pathways were enriched, including the most common cancer-associated forkhead box O signaling pathway (P=0.0077), microRNAs in cancer (P=0.0183) and the cAMP signaling pathway (P=0.0415). Furthermore, a network analysis identified three hub genes (HUWE1, PPP1CB and HSPA4), which were all involved in tumor metastasis. Taken together, the DEGs, significant pathways and hub genes identified in the present study shed some light on the molecular mechanisms of ENO1 involved in the pathogenesis of GC.

Forskolin exerts anticancer roles in non-Hodgkin's lymphomas via regulating Axin/β-catenin signaling pathway

Background

Non-Hodgkin’s lymphomas (NHLs) account for 85% of lymphomas, which are characterized by high-degree malignancy, rapid progress, and even invasion into central nervous system in pediatric patients. Although the cure rate of pediatric NHL has improved, some patients have still underwent recurrence or death. This study focuses on the effects and mechanism of forskolin on the progression of NHL, aiming to find efficient therapy methods for pediatric NHL.

Methods

MTT, flow cytometry and mice tumor bearing experiments were used to evaluate the effects of forskolin on NHL cell proliferation, apoptosis and tumorigenesis. Western blotting and RT-PCR assays were used to detect protein and mRNA expression. Immunohistochemistry technology was recruited to analyze Ki-67 expression in tumor tissues.

Results

Forskolin significantly increased the expression of cleaved caspase-3/9 in both NHL Toledo and NK-92 cell lines, and inhibited cell growth. Besides, forskolin obviously reduced the expression of β-catenin protein, promoted its ubiquitination, enhanced its transportation from nuclear to cytoplasm, as well as decreased the expression of its downstream oncogenes c-myc and cyclin D1 through upregulating Axin expression and stability and inhibiting Axin ubiquitination. Moreover, forskolin enhanced the effects of SP600125, an inhibitor of c-Jun N-terminal kinase signaling on cell apoptosis promotion and tumorigenesis inhibition via Axin-induced β-catenin signaling repression.

Conclusion

The current study clarifies that forskolin can inhibit the progression of NHL through Axin-mediated inhibition of β-catenin signaling. Moreover, forskolin improves the effects of SP600125 on cell apoptosis enhancement and tumorigenesis inhibition of NHL cells. These findings provide theoretical foundation of serving forskolin as a new effective therapeutic drug for pediatric NHL.

Selective and nonselective HDAC8 inhibitors: a therapeutic patent review

Histone deacetylase 8 (HDAC8) is one of the attractive therapeutic anticancer targets. HDAC8 has been overexpressed in a variety of human cancers. Therefore, HDAC8 inhibitors offer beneficial effects in the treatment of solid and hematological tumors. Different HDAC inhibitors entered into different phases of clinical studies. However, selectivity towards specific HDAC8 enzyme is still demanding. In this patent review, a number of patented selective and nonselective HDAC8 inhibitors along with their implication as anticancer agents have been discussed in details. Molecules should possess modified fish-like structural arrangement to impart potency and selectivity towards HDAC8. This comprehensive patent analysis will surely provide newer aspects of designing selective HDAC8 inhibitors targeted to anticancer therapy in future.

Role of miR-142 in the pathogenesis of osteosarcoma and its potential as therapeutic approach

Osteosarcoma (OS) is the most common primary malignant tumor of the bone with a strong tendency to early metastasis, and occurs in growing bones more commonly in children and adolescents. Considering the limited therapeutic methods and lack of 100% success of these methods, developing innovative therapies with high efficacy and lower side effects is needed. Meanwhile, miRNAs and the studies indicating the involvement of miRNAs in OS development have attracted attentions as a result of the frequent abnormalities in expression of miRNAs in cancer. miRNAs are noncoding short sequences with lengths ranging from 18 to 25 nucleotides that play a very important role in cellular processes, such as proliferation, differentiation, migration, and apoptosis. MiRNAs can have either oncogenic or tumor suppressive role based on cellular function and targets. This review aimed to have overview on miR-142 as a tumor suppressor in OS. Moreover, the genes involved in the disease, such as RAC1, HMAG1, MMP9, MMP2, and E-cadherin, which have irregularities as a result of change in miR-142 expression, and, thereby, result in increasing the proliferation, invasion, and metastasis of the cells in the tissues and OS cells will be discussed.

Class I histone deacetylases in retinal progenitors and differentiating ganglion cells

BACKGROUND

The acetylation state of histones has been used as an indicator of the developmental state of progenitor and differentiating cells. The goal of this study was to determine the nuclear localization patterns of Class I histone deacetylases (HDACs) in retinal progenitor cells (RPCs) and retinal ganglion cells (RGCs), as the first step in understanding their potential importance in cell fate determination within the murine retina.

RESULTS

The only HDAC to label RPC nuclei at E16 and P5 was HDAC1. In contrast, there was generally increased nuclear localization of all Class I HDACs in differentiating RGCs. Between P5 and P30, SOX2 expression becomes restricted to Müller glial, cholinergic amacrine cells, and retinal astrocytes. Cholinergic amacrine showed a combination of changes in nuclear localization of Class I HDACs. Strikingly, although Müller glia and retinal astrocytes express many of the same genes, P30 Müller glial cells showed nuclear localization only of HDAC1, while retinal astrocytes were positive for HDACs 1, 2, and 3.

CONCLUSION

These results indicate there may be a role for one or more of the Class I HDACs in retinal cell type-specific differentiation.

miR-433 inhibits breast cancer cell growth via the MAPK signaling pathway by targeting Rap1a

Breast cancer is one of the most lethal cancers in the world. The fight against breast cancer has also become a major task for medical workers. MicroRNAs (miRNAs) are often aberrantly expressed in diverse cancers and are involved in progression and metastasis. Many studies have found that miRNAs can act as oncogenes or as tumor suppressor genes. Here, we show that miR-433 is significantly decreased in breast cancer cells. In addition, we demonstrate the effects of miR-433 on breast cancer cell apoptosis, migration and proliferation in an attempt to elucidate the mechanism of action of miR-433. Moreover, Rap1a was predicted to be a potential target of miR-433 using bioinformatic approaches, and we found that the expression of Rap1a is inversely correlated with the level of miR-433. Further studies through overexpression and knockdown of Rap1a confirmed that Rap1a, as a direct target gene of miR-433, contributes to the functions of miR-433. In addition, we found that Rap1a activates the MAPK signaling pathway, which can contribute to cell migration and proliferation and can inhibit apoptosis. Overall, these findings highlight miR-433 as a tumor suppressor gene in the regulation of the progression and metastatic potential of breast cancer and may benefit the future development of therapies targeting miR-433 in breast cancer.

Effect of A549 neuroendocrine differentiation on cytotoxic immune response

The present study was designed to determine the effects of factors secreted by the lung adenocarcinoma cell line with the neuroendocrine phenotype, A549_NED, on cytotoxic T lymphocytes (CTLs) activity in vitro A perspective that integrates the nervous, endocrine and immune system in cancer research is essential to understand the complexity of dynamic interactions in tumours. Extensive clinical research suggests that neuroendocrine differentiation (NED) is correlated with worse patient outcomes; however, little is known regarding the effects of neuroendocrine factors on the communication between the immune system and neoplastic cells. The human lung cancer cell line A549 was induced to NED (A549_NED) using cAMP-elevating agents. The A549_NED cells showed changes in cell morphology, an inhibition of proliferation, an overexpression of chromogranin and a differential pattern of biogenic amine production (decreased dopamine and increased serotonin [5-HT] levels). Using co-cultures to determine the cytolytic CTLs activity on target cells, we showed that the acquisition of NED inhibits the decrease in the viability of the target cells and release of fluorescence. Additionally, the conditioned medium of A549_NED and 5-HT considerably decreased the viability and proliferation of the Jurkat cells after 24 h. Thus, our study successfully generated a neuroendocrine phenotype from the A549 cell line. In co-cultures with CTLs, the pattern of secretion by A549_NED impaired the proliferation and cytotoxic activity of CTLs, which might be partly explained by the increased release of 5-HT.

Inhibition of Epac2 Attenuates Neural Cell Apoptosis and Improves Neurological Deficits in a Rat Model of Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of mortality and disability worldwide. TBI-induced neuronal apoptosis is one of the main contributors to the secondary injury process. The aim of this study is to investigate the involvement of Exchange protein directly activated by cAMP 2 (Epac2) on TBI. We found that the expression level of Epac2 surrounding the injured area of brain in rats of TBI model was significantly increased at 12 h after TBI. The role of Epac2 in TBI was further explored by using a selective Epac2 antagonist ESI-05 to decrease the Epac2 expression. We discovered that inhibition of Epac2 could improve the neurological impairment and attenuate brain edema following TBI. The Epac2 inhibition effectively reduced neuronal cell death and P38 MAPK signaling pathway may be involved in this process. Our results suggest that inhibition of Epac2 may be a potential therapy for TBI by reducing the neural cell death, alleviating brain edema and improving neurologic deficits.

Intracellular cAMP Sensor EPAC: Physiology, Pathophysiology, and Therapeutics Development

This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses. This review comprehensively covers EPAC protein functions at the molecular, cellular, physiological, and pathophysiological levels; and in turn, the applications of employing EPAC-based biosensors as detection tools for dissecting cAMP signaling and the implications for targeting EPAC proteins for therapeutic development are also discussed.

Insights into exchange factor directly activated by cAMP (EPAC) as potential target for cancer treatment

Cancer remains a global health problem and approximately 1.7 million new cancer cases are diagnosed every year worldwide. Although diverse molecules are currently being explored as targets for cancer therapy the tumor treatment and therapy is highly tricky. Secondary messengers are important for hormone-mediated signaling pathway. Cyclic AMP (cAMP), a secondary messenger responsible for various physiological processes regulates cell metabolism by activating Protein kinase A (PKA) and by targeting exchange protein directly activated by cAMP (EPAC). EPAC is present in two isoforms EPAC1 and EPAC2, which exhibit different tissue distribution and is involved in GDP/GTP exchange along with activating Rap1- and Rap2-mediated signaling pathways. EPAC is also known for its dual role in cancer as pro- and anti-proliferative in addition to metastasis. Results after perturbing EPAC activity suggests its involvement in cancer cell migration, proliferation, and cytoskeleton remodeling which makes it a potential therapeutic target for cancer treatments.

Overexpression of exchange protein directly activated by cAMP-1 (EPAC1) attenuates bladder cancer cell migration

Exchange protein directly activated by cAMP (EPAC) is a mediator of a cAMP signaling pathway that is independent of protein kinase A. EPAC has two isoforms (EPAC1 and EPAC2) and is a cAMP-dependent guanine nucleotide exchange factor for the small GTPases, Rap1 and Rap2. Recent studies suggest that EPAC1 has both positive and negative influences on cancer and is involved in cell proliferation, apoptosis, migration and metastasis. We report that EPAC1 and EPAC2 expression levels were significantly lower in bladder cancer tissue than in normal bladder tissue. In addition, bladder cancer cell lines showed reduced EPAC1 mRNA expression. Furthermore, EPAC1 overexpression in bladder cancer cell lines induced morphologic changes and markedly suppressed cell migration without affecting cell viability. The overexpressed EPAC1 preferentially localized at cell-cell interfaces. In conclusion, reduced EPAC1 expression in bladder tumors and poor migration of EPAC1-overexpressing cells implicate EPAC1 as an inhibitor of bladder cancer cell migration.

Proinflammatory switch from Gαs to Gαi signaling by Glucagon-like peptide-1 receptor in murine splenic monocyte following burn injury

OBJECTIVE

Glucagon-like peptide-1 (GLP-1)-based therapy via G protein-coupled receptor (GPCR) GLP-1R, to attenuate hyperglycemia in critical care has attracted great attention. However, the exaggerated inflammation by GLP-1R agonist, Exendin-4, in a mouse model of burn injury was quite unexpected. Recent studies found that GPCR might elicit proinflammatory effects by switching from Gαs to Gαi signaling in the immune system. Thus, we aimed to investigate the possible Gαs to Gαi switch in GLP-1R signaling in monocyte following burn injury.

MATERIALS AND METHODS

Splenic monocytes from sham and burn mice 24 h following burn injury were treated with consecutive doses of Exendin-4 alone or in combination with an inhibitor of Gαi signaling (pertussis toxin, PTX), or a blocker of protein kinase A (H89). Cell viability was assessed by CCK-8, and the supernatant was collected for cytokine measurement by ELISA. Intracellular cAMP level, phosphorylated PKA activity, and nuclear NF-κB p65 were determined by ELISA, ERK1/2 activation was analyzed by Western blot. The expression of GLP-1R downstream molecules, Gαs, Gαi and G-protein coupled receptor kinase 2 (GRK2) were examined by immunofluorescence staining and Western blot.

RESULTS

Exendin-4 could inhibit the viability of monocyte from sham rather than burn mice. Unexpectedly, it could also reduce TNF-α secretion from sham monocyte while increase it from burn monocyte. The increased secretion of TNF-α by Exendin-4 from burn monocyte could be reversed by pretreatment of PTX or H89. Accordingly, Exendin-4 could stimulates cAMP production dose dependently from sham instead of burn monocyte. However, the blunt cAMP production from burn monocyte was further suppressed by pretreatment of PTX or H89 after 6-h incubation. Nevertheless, phosphorylated PKA activity was significantly increased by low dose of Exendin-4 in sham monocyte, by contrast, it was enhanced by high dose of Exendin-4 in burn monocyte after 1-h incubation. Following Exendin-4 treatment for 2 h ex vivo, total nuclear NF-κB and phosphorylated NF-κB activity, as well as cytoplasmic pERK1/2 expressions were reduced in sham monocyte, however, only pERK1/2 was increased by Exendin-4 in burn monocytes. Moreover, reduced expressions of GLP-1R, GRK-2 and Gαs in contrast with increased expression of Gαi were identified in burn monocyte relative to sham monocyte.

CONCLUSIONS

This study presents an unexpected proinflammatory switch from Gαs to Gαi signaling in burn monocyte, which promotes ERK1/2 and NF-κB activation and the downstream TNF-α secretion. This phenomenon is most probably responsible for proinflammatory response evoked by Gαs agonist Exendin-4 following burn injury.