Inhibitory heterotrimeric GTP-binding proteins inhibit hydrogen peroxide-induced apoptosis by up-regulation of Bcl-2 via NF-kappaB in H1299 human lung cancer cells

A Prognostic Nomogram Model Based on mRNA Expression of DNA Methylation-Driven Genes for Gastric Cancer

PURPOSE

The exploration and interpretation of DNA methylation-driven genes might contribute to molecular classification, prognostic prediction and therapeutic choice. In this study, we built a prognostic risk model via integrating analysis of the transcriptome and methylation profile for patients with gastric cancer (GC).

METHODS

The mRNA expression profiles, DNA methylation profiles and corresponding clinicopathological information of 415 GC patients were downloaded from The Cancer Genome Atlas (TCGA). Differential expression and correlation analysis were performed to identify DNA methylation-driven genes. The candidate genes were selected by univariate Cox regression analyses followed by the least absolute shrinkage and selection operator (LASSO) regression. A prognostic risk nomogram model was then built together with clinicopathological parameters.

RESULTS

5 DNA methylation-driven genes (CXCL3, F5, GNAI1, GAMT and GHR) were identified by integrated analyses and selected to construct the prognostic risk model with clinicopathological parameters. High expression and low DNA hypermethylation of F5, GNAI1, GAMT and GHR, as well as low expression and high DNA hypomethylation of CXCL3 were significantly associated with poor prognosis rates, respectively. The high-risk group showed a significantly shorter prognosis than the low-risk group in the TCGA dataset (HR = 0.212, 95% CI = 0.139-0.322, P = 2e-15). The final nomogram model showed high predictive efficiency and consistency in the training and validation group.

CONCLUSION

We construct and validate a prognostic nomogram model for GC based on five DNA methylation-driven genes with high performance and stability. This nomogram model might be a powerful tool for prognosis evaluation in the clinic and also provided novel insights into the epigenetics in GC.

Quinonoids: Therapeutic Potential for Lung Cancer Treatment

Lung cancer is the leading cause of cancer-related deaths worldwide. Owing to its high incidence and mortality, the development and discovery of novel anticancer drugs is of great importance. In recent years, many breakthroughs have been achieved in the search for effective anticancer substances from natural products. Many anticancer drugs used clinically and proven to be effective are derived from natural products. Quinonoids, including naphthoquinones, phenanthrenequinones, benzoquinones, and anthraquinones, constitute a large group of natural bioactive compounds that widely exist in higher and lower plant species. Given that most of these compounds possess anticancer effects, they are applied in many cancer studies, especially in lung cancer research. They can promote apoptosis, induce autophagy, and inhibit proliferation, angiogenesis, and cell invasion and migration. Some drugs can enhance anticancer effects when combined with other drugs. Thus, quinonoids have broad application prospects in the treatment of lung cancer. Here, we summarize the previous studies on the antilung cancer activities of quinonoids together with their underlying mechanisms and analyze the common research targets with different effects so as to provide references for the discovery of quinonoids against lung cancer.

TRIM32 overexpression improves chemoresistance through regulation of mitochondrial function in non-small-cell lung cancers

Background

TRIM32 is overexpressed in several human cancers. However, its expression pattern, biological characteristics and mechanisms in human non-small cell lung cancer (NSCLC) have not been reported.

Methods

We examined TRIM32 protein in 115 cases of NSCLC specimens. TRIM32 plasmid transfection and siRNA knockdown was carried out in NSCLC cell lines. AnnexinV/PI and JC-1 staining were performed to examine the change of apoptosis and mitochondrial membrane potential. Western blot was used to detect change of downstream proteins.

Results

We found that TRIM32 protein was upregulated in 69 cases and positively correlated with advanced TNM stage. TRIM32 overexpression also correlated with poor survival of NSCLC patients. Biological assays demonstrated that TRIM32 overexpression promoted while it depletion inhibited cell growth, colony formation and invasion. In addition, TRIM32 maintained NSCLC cell viability and reduced apoptosis when treated with cisplatin. JC-1 and CellRox staining demonstrated that TRIM32 could maintain mitochondrial membrane potential and reduce Reactive Oxygen Species (ROS) production after cisplatin treatment. Western blot analysis showed that TRIM32 overexpression downregulated caspase 3 cleavage and cytochrome c release. TRIM32 also positively regulated Bcl-2 protein expression and NF-κB signaling. Inhibition of NF-κB abolished the effects of TRIM32 on Bcl-2.

Conclusion

Taken together, our results indicated that TRIM32 is overexpressed in NSCLC and regulates cisplatin resistance, possibly through NF-κB and Bcl-2.

Exogenous C₈-Ceramide Induces Apoptosis by Overproduction of ROS and the Switch of Superoxide Dismutases SOD1 to SOD2 in Human Lung Cancer Cells

Ceramides, abundant sphingolipids on the cell membrane, can act as signaling molecules to regulate cellular functions including cell viability. Exogenous ceramide has been shown to exert potent anti-proliferative effects against cancer cells, but little is known about how it affects reactive oxygen species (ROS) in lung cancer cells. In this study, we investigated the effect of N-octanoyl-D-erythro-sphingosine (C₈-ceramide) on human non-small-cell lung cancer H1299 cells. Flow cytometry-based assays indicated that C₈-ceramide increased the level of endogenous ROS in H1299 cells. Interestingly, the ratio of superoxide dismutases (SODs) SOD1 and SOD2 seem to be regulated by C₈-ceramide treatment. Furthermore, the accumulation of cell cycle G1 phase and apoptotic populations in C₈-ceramide-treated H1299 cells was observed. The results of the Western blot showed that C₈-ceramide causes a dramatically increased protein level of cyclin D1, a critical regulator of cell cycle G1/S transition. These results suggest that C₈-ceramide acts as a potent chemotherapeutic agent and may increase the endogenous ROS level by regulating the switch of SOD1 and SOD2, causing the anti-proliferation, and consequently triggering the apoptosis of NSCLC H1299 cells. Accordingly, our works may give a promising strategy for lung cancer treatment in the future.

Rab11 Functions as an Oncoprotein via Nuclear Factor kappa B (NF-κB) Signaling Pathway in Human Bladder Carcinoma

Background

Elevated expression of Rab11 has been reported in different human cancers, including human bladder carcinoma. This study, we investigated the biological effects and mechanism of Rab11 overexpression in human bladder carcinoma for the first time.

Material/Methods

Rab11 expression in bladder cancer tissues was detected using immunohistochemistry and Western blot analysis. Then, Rab11 expression was inhibited in T24 cells and it was overexpressed in BIU-87 cells. The effects of Rab11 perturbations on cell growth rate and invasion were analyzed by CCK8, cell cycle assay, and matrix gel invasion assay. MMP-9, cyclin E, and cyclin D1 levels were studied using Western blot and qPCR. NF-κB activity was studied by luciferase assay.

Results

High expression of Rab11 was detected in 41.5% (66/159) of tumor specimens. We found a significant correlation between high Rab11 expression and depth of tumor invasion (P=0.004). Rab11 overexpression was observed to promote the growth rate and invasiveness of cancer cells through upregulation of MMP9, cyclin E, and cyclin D1 levels. Rab11 overexpression further elevated NF-κB reporter activity and enhanced p-IκB expression. Use of BAY 11-7082, a noted NF-κB inhibitor, partially abolished overexpression of MMP9 and cyclin D1 by Rab11.

Conclusions

Our research proved that high Rab11 expression enhances cellular multiplication and invasiveness of bladder cancer, possibly by regulating the NF-κB signaling pathway.

MiR-138: A promising therapeutic target for cancer

MicroRNAs are small noncoding RNAs which regulate gene expressions at post-transcriptional level by binding to the 3'-untranslated region of target messenger RNAs. Growing evidences highlight their pivotal roles in various biological processes of human cancers. Among them, miR-138, generating from two primary transcripts, pri-miR-138-1 and pri-miR-138-2, expresses aberrantly in different cancers and is extensively studied in cancer network. Importantly, studies have shown that miR-138 acts as a tumor suppressor by targeting many target genes, which are related to proliferation, apoptosis, invasion, and migration. Additionally, some researches also discover that miR-138 can sensitize tumors to chemotherapies. In this review, we summarize the expression of miR-138 on regulatory mechanisms and tumor biological processes, which will establish molecular basis on the usage of miR-138 in clinical applications in the future.

TRIM29 Overexpression Promotes Proliferation and Survival of Bladder Cancer Cells through NF-κB Signaling

Purpose

TRIM29 overexpression has been reported in several human malignancies and showed correlation with cancer cell malignancy. The aim of the current study is to examine its clinical significance and biological roles in human bladder cancer tissues and cell lines.

Materials and Methods

A total of 102 cases of bladder cancer tissues were examined for TRIM29 expression by immunohistochemistry. siRNA and plasmid transfection were performed in 5637 and BIU-87 cell lines. Cell Counting Kit-8, flow cytometry, western blot, and real-time polymerase chain reaction were performed to examine its biological roles and mechanism in bladder cancer cells.

Results

We found that TRIM29 overexpression showed correlation with invading depth (p=0.0087). Knockdown of TRIM29 expression in bladder cancer cell line 5637 inhibited cell growth rate and cell cycle transition while its overexpression in BIU-87 cells accelerated cell proliferation and cell cycle progression. TRIM29 overexpression also inhibited cell apoptosis induced by cisplatin. In addition, we demonstrated that TRIM29 depletion decreased while its overexpression led to upregulated expression of cyclin D1, cyclin E, and Bcl-2. We also showed that TRIM29 knockdown inhibited protein kinase C (PKC) and nuclear factor κB (NF-κB) signaling while its overexpression stimulated the PKC and NF-κB pathways. BAY 11-7082 (NF-κB inhibitor) partly attenuated the effect of TRIM29 on expression of cyclin and Bcl-2. Treatment with PKC inhibitor staurosporine resulted in ameliorated TRIM29 induced activation of NF-κB.

Conclusion

The current study demonstrated that TRIM29 upregulates cyclin and Bcl family proteins level to facilitate malignant cell growth and inhibit drug-induced apoptosis in bladder cancer, possibly through PKC–NF-κB signaling pathways.

Rab23 is overexpressed in human bladder cancer and promotes cancer cell proliferation and invasion

Rab23 overexpression has been implicated in several human cancers. However, its expression pattern and biological roles in human bladder cancer have not been elucidated. In this study, we examined Rab23 expression in 93 bladder cancer specimens and analyzed its correlation with clinicopathological parameters. We found that Rab23 was overexpressed in 45 of 93 (48.3 %) cancer specimens. Significant association was found between Rab23 overexpression and tumor invasion depth (p = 0.0027). Rab23 overexpression also negatively correlated with FGFR3 protein expression (p = 0.021). We found that Rab23 expression was lower in normal bladder transitional cell line SV-HUC-1 than in bladder cancer cell lines BIU-87, 5637, and T24. We knocked down Rab23 expression in T24 cancer cells and transfected a Rab23 plasmid in the BIU-87 cell line. Rab23 depletion inhibited cell growth rate and invasion, while its overexpression resulted in increased cell growth and invasion. In addition, we demonstrated that Rab23 depletion decreased and its transfection upregulated expression of cyclin E, c-myc, and MMP-9. Furthermore, we showed that Rab23 knockdown inhibited NF-κB signaling and its overexpression upregulated NF-κB signaling. BAY 11-7082 (NF-κB inhibitor) partly inhibited the effect of Rab23 on cyclin E and MMP-9 expression. In conclusion, the present study demonstrated that Rab23 overexpression facilitates malignant cell growth and invasion in bladder cancer through the NF-κB pathway.

MiR-525-3p enhances the migration and invasion of liver cancer cells by downregulating ZNF395

Liver cancer is one of leading causes of cancer-related deaths. A deeper mechanistic understanding of liver cancer could lead to the development of more effective therapeutic strategies. In our previous work, we screened 646 miRNAs and identified 11 that regulate liver cancer cell migration. The current study shows that miR-525-3p is frequently up-regulated in liver cancer tissues, and enhanced expression of miR-525-3p can promote liver cancer cell migration and invasion. Zinc finger protein 395 (ZNF395) is the direct functional target gene for miR-525-3p, and it is frequently down-regulated in liver cancer tissues. High expression of ZNF395 can significantly inhibit while knockdown of ZNF395 expression can markedly enhance the migration and invasion of liver cancer cells, suggesting that ZNF395 suppresses metastasis in liver cancer. Down-regulation of ZNF395 can mediate miR-525-3p induced liver cancer cell migration and invasion. In conclusion, miR-525-3p promotes liver cancer cell migration and invasion by directly targeting ZNF395, and the fact that miR-525-3p and ZNF395 both play important roles in liver cancer progression makes them potential therapeutic targets.

Total glucosides of paeony inhibit the proliferation of fibroblast-like synoviocytes through the regulation of G proteins in rats with collagen-induced arthritis

The aim of this study was to investigate the expression of G proteins in fibroblast-like synoviocytes (FLSs) from rats with collagen-induced arthritis (CIA) and to determine the effect of total glucosides of paeony (TGP). CIA rats were induced with chicken type II collagen (CCII) in Freund's complete adjuvant. The rats with experimental arthritis were randomly separated into five groups and then treated with TGP (25, 50, and 100mg/kg) from days 14 to 35 after immunization. The secondary inflammatory reactions were evaluated through the polyarthritis index and histopathological changes. The level of cyclic adenosine monophosphate (cAMP) was measured by radioimmunoassay. The FLS proliferation response was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The toxin-catalyzed ADP-ribosylation of G proteins was performed through autoradiography. The results show that TGP (25, 50, and 100mg/kg) significantly decreased the arthritis scores of CIA rats and improved the histopathological changes. TGP inhibited the proliferation of FLSs and increased the level of cAMP. Moreover, the FLS proliferation and the level of Gαi expression were significantly increased, but the level of Gαs expression was decreased after stimulation with IL-1β (10ng/ml) in vitro. TGP (12.5 and 62.5μg/ml) significantly inhibited the FLS proliferation and regulated the balance between Gαi and Gαs. These results demonstrate that TGP may exert its anti-inflammatory effects through the suppression of FLS proliferation, which may be associated with its ability to regulate the balance of G proteins. Thus, TGP may have potential as a therapeutic agent for the treatment of rheumatoid arthritis.

Feruloyl-L-arabinose attenuates migration, invasion and production of reactive oxygen species in H1299 lung cancer cells

Ferulic acid (FA), a phenolic compound, is an abundant dietary antioxidant and exerts the mitogenic effect on cells. Recently, we isolated an active FA derivative, namely feruloyl-L-arabinose (FAA), from coba husk. The aim of this study was to investigate the effects of FAA on the proliferation, migration and invasion of H1299 human lung cancer cells. Our results showed a strong antioxidant potential of FAA. Additionally, FAA inhibited the migration and invasion ability, while causing a significant accumulation of G2/M-population, of H1299 tumor cells in a dose-dependent manner, whereas no significant change on cell proliferation was observed. Results from the wound healing assay revealed that cell migration ability was markedly inhibited by FAA treatments. Similarly, results of gelatin zymography study showed that FAA treatments significantly decreased the activities of matrix metalloproteinase (MMP)-2 and MMP-9, suggesting that FAA-mediated inhibition on migration and invasion of lung cancer cells may be achieved by the down-regulation of the MMPs activities. Taken together, our present work provides a new insight into the novel inhibitory function of FAA on cell migration in H1299 cells, suggesting its promising role in the chemoprevention of lung cancer.

GNAI1 Suppresses Tumor Cell Migration and Invasion and is Post-Transcriptionally Regulated by Mir-320a/c/d in Hepatocellular Carcinoma

Objective

To explore the role and regulation of guanine nucleotide-binding protein G(i), α-1 subunit (GNAI1) in hepatocellular carcinoma (HCC).

Methods

Expression of GNAI1 in HCC samples was determined by qRT–PCR and immunohistochemical (IHC) staining. Huh-7 and SNU-387 cells stably expressing GNAI1 were established by the infection of lentivirus transducing unit containing GNAI1. siRNA against GNAI1 was transfected into SMMC-7721 cells to knock down the GNAI1 expression in HCC cells. Mir-320a/c/d mimics were transfected into SMMC-7721 and SK-Hep-1 cells and the expression of GNAI1 was determined by Western blot. The migration and invasion of Huh-7, SNU-387, SK-Hep-1 and SMMC-7721 cells were investigated by Transwell assays.

Results

The GNAI1 protein was significantly downregulated in HCC samples without changes in its mRNA levels. GNAI1 could inhibit the migration and invasion of HCC cells in vitro. Further investigations indicated that GNAI1 was a target of miR-320a/c/d in HCC cells. Transwell assays demonstrated that these microRNAs could promote the migratory ability and invasivesess of HCC cells in vitro.

Conclusions

GNAI1 is downregulated in HCC and inhibits the migration and invasion of HCC cells. This study is the first to investigate the role of GNAI1 in cancer. Regulation of GNAI1 by miR-320a/c/d indicates new therapeutic avenues for targeting HCC metastasis.

Porcine epidemic diarrhea virus N protein prolongs S-phase cell cycle, induces endoplasmic reticulum stress, and up-regulates interleukin-8 expression

Porcine epidemic diarrhea (PED) is an acute and highly contagious enteric disease of swine caused by porcine epidemic diarrhea virus (PEDV). The porcine intestinal epithelial cell is the PEDV target cell. In this study, we established a porcine intestinal epithelial cell (IEC) line which can stably express PEDV N protein. We also investigate the subcellular localization and function of PEDV N protein by examining its effects on cell growth, cycle progression, interleukin-8 (IL-8) expression, and survival. The results show that the PEDV N protein localizes in the endoplasmic reticulum (ER), inhibits the IEC growth and prolongs S-phase cell cycle. The S-phase is prolonged which is associated with a decrease of cyclin A transcription level and an increase of cyclin A degradation. The IEC expressing PEDV N protein can express higher levels of IL-8 than control cells. Further studies show that PEDV N protein induces ER stress and activates NF-κB, which is responsible for the up-regulation of IL-8 and Bcl-2 expression. This is the first report to demonstrate that PEDV N protein can induce cell cycle prolongation at the S-phase, ER stress and up-regulation interleukin-8 expression. These findings provide novel information on the function of the PEDV N protein and are likely to be very useful in understanding the molecular mechanisms responsible for PEDV pathogenesis.

Porcine epidemic diarrhea virus E protein causes endoplasmic reticulum stress and up-regulates interleukin-8 expression

Background

Porcine epidemic diarrhea virus (PEDV) is an important pathogen in swine and is responsible for substantial economic losses. Previous studies suggest that the PEDV E protein plays an important role in the viral assembly process. However, the subcellular localization and other functions of PEDV E protein still require more research.

Methods

The subcellular localization and function of PEDV E protein were investigated by examining its effects on cell growth, cell cycle progression, interleukin-8 (IL-8) expression and cell survival.

Results

The results show that plenty of PEDV E protein is localized in the ER, with small quantities localized in the nucleus. The PEDV E protein has no effect on the intestinal epithelial cells (IEC) growth, cell cycle and cyclin A expression. The cells expressing PEDV E protein express higher levels of IL-8 than control cells. Further studies show that PEDV E protein induced endoplasmic reticulum (ER) stress and activated NF-κB which is responsible for the up-regulation of IL-8 and Bcl-2 expression.

Conclusions

This study shows that the PEDV E protein is localized in the ER and the nucleus and it can cause ER stress. The PEDV E protein had no effect on the IEC growth and cell cycle. In addition, the PEDV E protein is able to up-regulate IL-8 and Bcl-2 expression.

Effect of pertussis toxin and herbimycin A on proteinase-activated receptor 2-mediated cyclooxygenase 2 expression in Helicobacter pylori-infected gastric epithelial AGS cells

Helicobacter pylori (H. pylori) is an important risk factor for chronic gastritis, peptic ulcer, and gastric cancer. Proteinase-activated receptor 2 (PAR2), subgroup of G-protein coupled receptor family, is highly expressed in gastric cancer, and chronic expression of cyclooxygenase-2 (COX-2) plays an important role in H. pylori-associated gastric carcinogenesis and inflammation. We previously demonstrated that H. pylori induced the expression of PAR2 and COX-2 in gastric epithelial cells. Present study aims to investigate whether COX-2 expression induced by H. pylori in Korean isolates is mediated by PAR2 via activation of G(i) protein and Src kinase in gastric epithelial AGS cells. Results showed that H. pylori-induced COX-2 expression was inhibited in the cells transfected with antisense oligonucleotide for PAR2 or treated with Gi protein blocker pertussis toxin, Src kinase inhibitor herbimycin A and soybean trypsin inbitor, indicating that COX-2 expression is mediated by PAR2 through activation of Gi protein and Src kinase in gastric epithelial cells infected with H. pylori in Korean isolates. Thus, targeting the activation of PAR2 may be beneficial for prevention or treatment of gastric inflammation and carcinogenesis associated with H. pylori infection.

(-)-Anonaine induces DNA damage and inhibits growth and migration of human lung carcinoma h1299 cells

The anticancer effects of (-)-anonaine were investigated in this current study. (-)-Anonaine at concentration ranges of 50-200 μM exhibited significant inhibition to cell growth and migration activities on human lung cancer H1299 cells at 24 h, albeit cell cycle analyses showed that (-)-anonaine at the above concentration ranges did not cause any significant changes in cell-cycle distributions. Significant nuclear damages of H1299 cells were observed with 10-200 μM (-)-anonaine treatment in a comet assay, whereas higher concentrations (6 and 30 mM) of (-)-anonaine concentrations were required to cause DNA damages in an in vitro plasmid cleavage assay. In summary, our results demonstrated that (-)-anonaine exhibited dose-dependent antiproliferatory, antimigratory, and DNA-damaging effects on H1299 cells. We inferred that (-)-anonaine can cause cell-cycle arrest and DNA damage to hamper the physiological behavior of cancer cells at 72 h, and therefore, it can be useful as one of the potential herbal supplements for chemoprevention of human lung cancer.

Classical swine fever virus NS2 protein promotes interleukin-8 expression and inhibits MG132-induced apoptosis

Classical swine fever (CSF) caused by virulent strains of classical swine fever virus (CSFV) is a hemorrhagic disease of pigs and is characterized by disseminated intravascular coagulation, thrombocytopenia, and immunosuppression. Until now, the role of the NS2 protein produced by CSFV in the pathogenesis of CSF is not well understood. In this report, we investigated the function of CSFV NS2 by examining its effects on the pro-inflammatory CXC chemokine, interleukin-8 (IL-8) expression, and cell survival. Stable swine umbilical vein endothelial cell line (SUVEC) expressing CSFV NS2 were established and showed that CSFV NS2 expressing SUVEC cells express approximately 16-fold higher levels of IL-8 as compared to control vector GFP-expressing cells, GFP-E2 expressing cells, and untransfected cells. Further studies showed that CSFV NS2 induced endoplasmic reticulum stress and activated the nuclear transcription factor kappa B (NF-κB), which is responsible for the up-regulation of IL-8 and the anti-apoptotic protein, Bcl-2, expression. In addition, the GFPNS2-expressing SUVEC cells were resistant to MG132-induced apoptosis. This study suggested that CSFV NS2 plays an important role in the inflammatory response and in persistent CSFV infection. These findings provide novel information on the function of the poorly characterized CSFV NS2.

Protective effect of the methanolic extract from Duchesnea indica against oxidative stress in vitro and in vivo

Duchesnea indica (Rosaceae family) is herb used extensively in traditional Chinese medicine. In this study we investigated its protective activity against hydrogen peroxide (H(2)O(2))-induced cytotoxicity in human skin fibroblast (CCD-986Sk) cells and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced H(2)O(2) in the skin of hairless mice. Pretreatment of CCD-986Sk cells with methanolic extract of D. indica (DIM) improved the cell viability, enhanced activity of catalase, and decreased the leakage of lactate dehydrogenase (LDH) and the levels of malondialdehyde (MDA) and intracellular reactive oxygen species (ROS) in H(2)O(2) injured cells. Furthermore, DIM inhibited cell apoptosis and Bax expression induced by H(2)O(2). In addition, the level of H(2)O(2) stimulated by TPA was decreased by DIM in the skin of hairless mice. These results suggest that DIM offers protection against oxidative stress in vitro and in vivo, and this ability suggests potential use for protection against oxidation-induced skin damage.

Antioxidant and antiproliferative properties of water extract from Mahonia bealei (Fort.) Carr. leaves

Mahonia bealei (Fort.) Carr. (Berberidaceae) leaves have been widely used as a tea leaf beverage south of the Qinling Mountains of China. In this study, the antioxidant and antiproliferative properties of M. bealei leaves were investigated. Our data showed that the water extract of M. bealei leaves (WML) exhibited extremely high antioxidant properties, which were demonstrated by its ability to scavenge 50% of 1,1-diphenyll-2-2-pricylhydrazyl (DPPH) free radicals at 60.46 μg/ml, and it eliminated approximately 71.19% of superoxide radicals at 500 μg/ml. In addition, the WML showed strong reducing abilities and provided protection against oxidative protein damage induced by hydroxyl radicals. Cellular proliferation and the induction of apoptosis were also examined by cellular proliferation assay, flow cytometry, and mRNA expression analysis. These results demonstrate that WML significantly inhibited the growth of human colon cancer (HT-29) cells in a concentration-dependent manner, and it gradually increased the proportion of apoptotic cells and reduced the expression of the survivin gene. The bioactivity-guided study of WML resulted in the isolation and identification of berberine, a known isoquinoline alkaloid. Berberine exhibited strong antiproliferative activity on HT-29 cells, with IC(50) values of 36.54 μM, suggesting it is, in part, responsible of the anticancer activity of WML.

Identification and experimental validation of G protein alpha inhibiting activity polypeptide 2 (GNAI2) as a microRNA-138 target in tongue squamous cell carcinoma

MicroRNA deregulation is a critical event in tumor initiation and progression. The down-regulation of microRNA-138 has been frequently observed in various cancers, including tongue squamous cell carcinoma (TSCC). Our previous studies suggest that deregulation of miR-138 is associated with the enhanced proliferation and invasion in TSCC cells. Here, we seek to identify the targets of miR-138 in TSCC, and explore their functional relevance in tumorigenesis. Our genome-wide expression profiling experiments identified a panel of 194 unique transcripts that were significantly down-regulated in TSCC cells transfected with miR-138. A comprehensive screening using six different sequence-based microRNA target prediction algorithms revealed that 51 out of these 194 down-regulated transcripts are potential direct targets for miR-138. These targets include: chloride channel, nucleotide-sensitive, 1A (CLNS1A), G protein alpha inhibiting activity polypeptide 2 (GNAI2), solute carrier family 20, member 1 (SLC20A1), eukaryotic translation initiation factor 4E binding protein 1 (EIF4EBP1), and Rho-related GTP-binding protein C (RhoC). GNAI2 is a known proto-oncogene that is involved in the initiation and progression of several different types of tumors. Direct targeting of miR-138 to two candidate binding sequences located in the 3'-untranslated region of GNAI2 mRNA was confirmed using luciferase reporter gene assays. Knockdown of miR-138 in TSCC cells enhanced the expression of GNAI2 at both mRNA and protein levels. In contrast, ectopic transfection of miR-138 reduced the expression of GNAI2, which, in consequence, led to reduced proliferation, cell cycle arrest and apoptosis. In summary, we identified a number of high-confident miR-138 target genes, including proto-oncogene GNAI2, which may play an important role in TSCC initiation and progression.

Involvement of NF-kappaB activation in the apoptosis induced by extracellular adenosine in human hepatocellular carcinoma HepG2 cells

Adenosine can exhibit cytotoxic activity in vivo and in vitro, though its mechanisms are still uncertain. In this study, we investigated the adenosine-mediated apoptotic signaling pathway and the role of NF-kappaB in human hepatocellular carcinoma HepG2 cells. HepG2 cells were treated with different concentrations of adenosine for 12-48 h, and the effect of adenosine on cell proliferation was evaluated by MTT assay. The cytotoxicity of adenosine alone or in combination with an NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), was also evaluated by MTT assay and the mode of cell death was detected by Hoechst 33342 staining. Cell cycle progress was performed by flow cytometry with PI staining. The protein expressions of Bcl-2, p53, NF-kappaB subunit p65, and caspase-3 were assayed by Western blot. Caspase-3 activity was measured by spectrophotomteric assay. The results showed that adenosine significantly reduced the viability of HepG2 cells in a dose- and time-dependent manner, with IC 50 (24 and 48 h) of 2.52 and 1.89 mmol x L(-1), respectively. The apoptotic index (percentage of sub-G1 phase) of HepG2 cells in adenosine treatment alone for 12 and 24 h or in combination with PDTC were 8.30%, 22.32% and 20.18%, 30.89%, respectively. All of them were higher than that in the control group (0.81%, p < 0.01). The characteristic changes of cell apoptosis (chromatin condensation and sub-G1 peak) were observed under fluorescent microscopy and flow cytometry. We also found that the apoptotic process triggered by adenosine was involved in G0-G1 cell-cycle arrest, enhanced the activity of caspase-3, upregulated p53 and NF-kappaB p65 expression, and downregulated Bcl-2 expression. Inhibition of NF-kappaB by PDTC decreased NF-kappaB p65 expression, enhanced cell apoptosis ratio, and increased caspase-3 activity. NF-kappaB may play an anti-apoptosis role in adenosine-induced HepG2 cytotoxicity.

Stimulatory heterotrimeric G protein augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 human lung cancer cells

Stimulatory heterotrimeric GTP-binding proteins (Gs protein) stimulate cAMP generation in response to various signals, and modulate various cellular phenomena such as proliferation and apoptosis. This study aimed to investigate the effect of Gs proteins on gamma ray-induced apoptosis of lung cancer cells and its molecular mechanism, as an attempt to develop a new strategy to improve the therapeutic efficacy of gamma radiation. Expression of constitutively active mutant of the alpha subunit of Gs (GalphasQL) augmented gamma ray-induced apoptosis via mitochondrial dependent pathway when assessed by clonogenic assay, FACS analysis of PI stained cells, and western blot analysis of the cytoplasmic translocation of cytochrome C and the cleavage of caspase-3 and ploy(ADP-ribose) polymerase (PARP) in H1299 human lung cancer cells. GalphasQL up-regulated the Bak expression at the levels of protein and mRNA. Treatment with inhibitors of PKA (H89), SP600125 (JNK inhibitor), and a CRE-decoy blocked GalphasQL-stimulated Bak reporter luciferase activity. Expression of GalphasQL increased basal and gamma ray-induced luciferase activity of cAMP response element binding protein (CREB) and AP-1, and the binding of CREB and AP-1 to Bak promoter. Furthermore, prostaglandin E2, a Galphas activating signal, was found to augment gamma ray-induced apoptosis, which was abolished by treatment with a prostanoid receptor antagonist. These results indicate that Galphas augments gamma ray-induced apoptosis by up-regulation of Bak expression via CREB and AP-1 in H1299 lung cancer cells, suggesting that the efficacy of radiotherapy of lung cancer may be improved by modulating Gs signaling pathway.

Heterotrimeric G proteins and apoptosis: intersecting signaling pathways leading to context dependent phenotypes

Apoptosis, a programmed cell death mechanism, is a fundamental process during the normal development and somatic maintenance of all multicellular organisms and thus is highly conserved and tightly regulated through numerous signaling pathways. Apoptosis is of particular clinical importance as its dysregulation contributes significantly to numerous human diseases, primarily through changes in the expression and activation of key apoptotic regulators. Each of the four families of heterotrimeric G proteins (G(s), G(i/o), G(q/11) and G(12/13)) has been implicated in numerous cellular signaling processes, including proliferation, transformation, migration, differentiation, and apoptosis. Heterotrimeric G protein signaling is an important but not widely studied mechanism regulating apoptosis. G protein Signaling and Apoptosis broadly cover two large bodies of literature and share numerous signaling pathways. Examination of the intersection between these two areas is the focus of this review. Several studies have implicated signaling through each of the four heterotrimeric G protein families to regulate apoptosis within numerous disease contexts, but the mechanism(s) are not well defined. Each G protein family has been shown to stimulate and/or inhibit apoptosis in a context-dependent fashion through regulating numerous downstream effectors including the Bcl-2 family, NF-kappaB, PI3 Kinase, MAP Kinases, and small GTPases. These cell-type specific and G protein coupled receptor dependent effects have led to a complex body of literature of G protein regulation of apoptosis. Here, we review the literature and summarize apoptotic signaling through each of the four heterotrimeric G protein families (and the relevant G protein coupled receptors), and discuss limitations and future directions for research on regulating apoptosis through G protein coupled mechanisms. Continued investigation in this field is essential for the identification of important targets for pharmacological intervention in numerous diseases.