- [Show abstract] [Hide abstract] ABSTRACT: Base excision repair (BER) systems are important for maintaining the integrity of genomes in mammalian cells. Aberrant DNA bases or broken single strands can be repaired by BER. Consequently, DNA lesions, which may be caused by cancer and aging, have a close association with BER procedure. DNA polymerase β (polβ) is a critical BER enzyme that can excise 5'-sugar phosphate prior to adding a nucleotide in the gap by its function as a DNA polymerase in the BER process. However, DNA polβ is an error-prone DNA polymerase, and overexpressing polβ increases the cellular spontaneous mutation rate. DNA polβ overexpression has been identified in various human tumors, which implies that DNA polβ overexpression has a close association with tumorigenesis. The present study showed that alternariol (AOH), a secondary product of a fungus that is found in grains and fruits, could cause DNA damage to NIH3T3 cells in a single cell gel electrophoresis, and that 2, 10 and 20 µM AOH induced DNA polβ overexpression in a dose-dependent manner. In the process, the level of phosphorylation of mitogen-activated protein kinase 14 (p38) mitogen-activated protein kinase (MAPK) and activating transcription factor 2 (ATF2) was increased. In addition, SB203580, a p38MAPK inhibitor, resulted in decreased DNA polβ expression. Small hairpin RNA-p38MAPK had the same effect; notably, DNA polβ expression was downregulated in p38MAPK knockdown cells. These data suggest that the p38MAPK-ATF2 signaling pathway may be involved in DNA polβ expression induced by AOH.
- [Show abstract] [Hide abstract] ABSTRACT: Transmembrane tumor necrosis factor-α (tmTNF-α) is known to induce the activation of NF-κB to protect tumor cells. Upregulation of tmTNF-α leads to resistance to apoptosis and induces drug resistance in breast cancer. However, the expression of tmTNF-α in colorectal cancer (CRC) and its association with clinical outcome in CRC have remained unclear. In this study, we examined the tmTNF-α expression in CRC by immunohistochemistry and western blotting, assessed the prognostic value of tmTNF-α related to the recurrence/metastasis and survival of stage II/III CRC by the Kaplan-Meier survival curve and Cox regression model, and also explored the role of tmTNF-α expression on the chemotherapeutic efficacy of 5-Fluorouracil by flow cytometry assay and cell counting kit-8 (CCK-8) in vitro. Overall, we found that 77 (78.6%) out of 98 patients exhibited higher tmTNF-α expression in the CRC tissues comparing with the adjacent tissues. The tmTNF-α expression was correlated with Differentiation (P = 0.019), TNM stage (P = 0.039), Lymph nodes metastasis (P = 0.024) and Lymphovascular invasion (P = 0.027) but not related with Age (P = 0.617), Gender (P = 0.625), Tumor location (P = 0.138), Perforation/Obstruction (P = 1.000), Depth of invasion (P = 0.327), and microsatellite instability status (P = 0.150). The prognostic analyses showed that high tmTNF-α expression patients was significantly associated with decreased Disease-Free Survival (P = 0.0209) and Overall Survival (P = 0.0163). CCK-8 results suggested that the tmTNF-α influenced the chemotherapeutic effect of 5-Fluorouracil on colon cancer cells. Altogether, these data indicated the stage II/III CRC patients with high tmTNF-α expression were more likely to have a worse prognosis than patients with low tmTNF-α expression and tmTNF-α may influence the chemotherapeutic effect of 5-Fluorouracil. The mechanism for these observations warrants further study.
- [Show abstract] [Hide abstract] ABSTRACT: Histone deacetylase (HDAC)‑mediated epigenetic modification plays crucial roles in numerous biological processes, including cell cycle regulation, cell proliferation and apoptosis. HDAC inhibitors demonstrate antitumor effects in various cancers, including glioblastoma and breast cancer. HDAC inhibitors are therefore promising antitumor drugs for these tumors. The tumorigenesis and development of esophageal squamous cell carcinoma (ESCC) involve genetic and epigenetic mechanisms. However, the effects of the HDAC inhibitor on ESCC are not fully investigated. In the present study, ESCC cells were treated with trichostatin A (TSA) and its antitumor effects and related mechanisms were investigated. The results indicated that TSA suppressed the proliferation of ESCCs and caused G1 phase arrest by inducing the expression of p21 and p27. TSA also induced cell apoptosis by enhancing the expression of pro‑apoptotic protein Bax and decreasing the expression of anti‑apoptotic protein Bcl‑2. Furthermore, TSA inhibited the expression of phosphatidylinositol‑3‑kinase (PI3K) and reduced the phosphorylation of Akt and extracellular signal‑regulated kinase (ERK)1/2 in EC9706 and EC1 cell lines. High levels of acetylated histone H4 were detected in TSA‑treated ESCC cell lines. Overall, these results indicate that TSA suppresses ESCC cell growth by inhibiting the activation of the PI3K/Akt and ERK1/2 pathways. TSA also promotes cell apoptosis through epigenetic regulation of the expression of apoptosis‑related protein.
- [Show abstract] [Hide abstract] ABSTRACT: Esophageal cancer is an intractable disease due to late diagnosis, high incidence of post-surgical locoregional recurrence and frequent distant metastasis. Oncolytic adenovirus (Ad) vectors are a promising method for cancer treatment. The H101 virus is a recombinant Ad which has replication-selective properties and replicates only in tumor cells. The coxsackievirus and adenovirus receptor (CAR) is considered a surrogate marker that monitors the outcome of Ad-mediated gene therapy. Accumulating evidence indicates that CAR expression levels are lower in various types of tumors such as ovarian, lung, breast and bladder when compared to their normal counterparts. In this study, we reported that trichostatin A (TSA) induced the expression of CAR in esophageal squamous cell carcinoma (ESCC) cell lines through the MAPK/ERK1/2 signaling pathway. The expression levels of CAR were positively related with the antitumor activity of H101. Our results suggest that TSA increases the antitumor activity of the oncolytic adenovirus H101 through the MAPK/ERK pathway.
- [Show abstract] [Hide abstract] ABSTRACT: Alternariol (AOH) is a mycotoxin of Alternaria alternata and can cause DNA damage and gene mutations. Low-dose and long-term treatment with AOH has been linked with incidence of esophageal carcinoma. DNA polymerase β (polβ) is a key enzyme in DNA base excision repair (BER). When it is overexpressed or mutated in cells, DNA polβ can cause genetic instability. Elevated DNA polβ has also been reported in several human cancers. Here, we report that AOH at 2, 10, 20 µM induces DNA polβ expression. In the process, protein kinase A (PKA) catalytic subunit activation, nuclear translocation and cAMP response element binding protein (CREB) phosphorylation are involved. AOH also increased CREB binding to the cAMP response element (CRE) consensus motif, which is present in the DNA polβ gene promoter. The PKA inhibitor H89 was able to block AOH-induced PKA-CREB activation, CREB DNA binding activity and decrease DNA polβ expression. Our results suggest that AOH can upregulate DNA polβ expression through the PKA-CREB signal transduction pathway.
- [Show abstract] [Hide abstract] ABSTRACT: Dendritic cells (DCs) are professional antigen-presenting cells that play an important role in anti-tumour immunity. Endothelial-like differentiation of DCs is an interesting phenomenon. The specific role of vascular endothelial growth factor-A (VEGF-A) on the differentiation of immature DCs (iDCs) and mature DCs (mDCs) is worth further research. Here, we show that VEGF-A can induce iDCs to differentiate into endothelial-like cells (ELCs). But it has no obvious influence on mDCs. In the process of endothelial-like differentiation of iDCs, a sustained activation of extracellular signal-regulated kinase (ERK1/2) and cAMP response element binding protein (CREB) was detected. VEGF-A induced the activation of ERK1/2, and led to the nuclear translocation of phosphorylation ERK1/2. Incubation of iDCs with the ERK1/2 upstream kinase MEK1/2 inhibitor PD98059, blocked the phosphorylation of ERK1/2 and CREB as well as the endothelial-like differentiation of iDCs. These data suggest that VEGF-A induces endothelial-like differentiation of iDCs not mDCs through ERK1/2 signalling pathway.
- [Show abstract] [Hide abstract] ABSTRACT: Endothelial-like differentiation of dendritic cells (DCs) is an interesting and significant phenomenon, which is worth further investigation. Here, we show that the tumor microenvironment derived from the supernatant of the SW620 human colon adenocarcinoma cell line and colon adenocarcinoma tissue homogenate can promote immature DCs (iDCs) to differentiate from the DC pathway toward endothelial cells, while the peri-carcinoma homogenate supernatant does not have this role. Inhibition of angiopoietin-2 (Ang2) in the supernatant by its antibody has no obvious influence on the endothelial-like differentiation. In contrast, inhibition of vascular endothelial growth factor-A (VEGF-A) blocked the differentiation. During the course of differentiation, a sustained activation of ERK1/2 was detected. PD98059 blocked the phosphorylation of ERK1/2 as well as the endothelial-like differentiation of iDCs. Inhibition of VEGF-A also blocked the phosphorylation of ERK1/2. These data suggest that VEGF-A not Ang2 mediates endothelial-like differentiation of iDCs by ERK1/2 signaling in the microenvironment of human colon adenocarcinoma.
- [Show abstract] [Hide abstract] ABSTRACT: Endothelial-like differentiation of dendritic cells (DCs) is a new phenomenon, and the mechanism is still elusive. Here, we show that the tumor microenvironment derived from the human esophageal squamous cell carcinoma (ESCC) cell line EC9706 can induce immature DCs (iDCs) differentiate toward endothelial cells, and become endothelial-like cells, but it has no obvious influence on mature DCs. During the course of endothelial-like differentiation of iDCs, a sustained activation of mitogen-activated protein kinase/extracelluar signal-regulated kinase1/2 (MAPK/ERK1/2) and cAMP response element-binding protein (CREB) was detected. Incubation of iDCs with MEK phosphorylation inhibitor PD98059 blocked the MAPK/ERK1/2 and CREB phosphorylation as well as the endothelial-like differentiation of iDCs. Inhibition of vascular endothelial growth factor-A (VEGF-A) in the microenvironment with its antibody blocked the endothelial-like differentiation and the phosphorylation of MAPK/ERK1/2 and CREB. These data suggest that MAPK/ERK1/2 signaling pathway activated by VEGF-A could mediate endothelial-like differentiation of iDCs in the ESCC microenvironment.
- [Show abstract] [Hide abstract] ABSTRACT: To study the cytotoxicity of altemariol (AOH) on NIH/3T3 cells. Logarithmic growth phase NIH/3T3 cells were treated at the dose of 10 micromol/L and 50 micromol/L AOH as treatment groups and treated with DMSO (0.25%). The effects of AOH on cell proliferations were assessed by morphologic observasion. Inhibition rates of AOH were determined by MTT assay. Comet assay was used to examine DNA damage induced by AOH. Cell cycle distributions were detected by flow cytometric assay (FCM). The cells treated with AOH occured morlogic changes. The inhibition rates of 10 micromol/L and 50 micromol/L AOH were 19.88% and 32.47% respectively. In the comet assay two treatment groups percentages of tailed cells were 35.87% and 71.83% respectively. The DNA contents of the tail were (36.18 +/- 18.6) and (51.3 +/- 21.6) respectively. These datas were more higher than those of the solvent control (P < 0.05). In comparison with the control group, the percents of G2/M and S phase cells were increased after treatment of 50.0 micromol/L AOH for 24h (P < 0.05). AOH could have acute cytotoxic effects on NIH/3T3 cells and inhibite cell proliferation and cause DNA damage. High dose of AOH could induce cell cycle arrest in G2/M phase.
- [Show abstract] [Hide abstract] ABSTRACT: AIM: To prepare the vaccine of DCs (pcDNA3 - hCEA) and observ the immunity effect of the DCs (pcDNA3 - hCEA) inoculating on CT26(hCEA+ ) loaded in BALB/ c mice. METHODS : DCs were generated from bone marrow in the presence of rmGM - CSF and rmIL - 4. A new recombinant plasmid , pcDNA3 - hCEA , with inserting a 2. 4 kb human CEA cDNA into pcDNA3. DC vaccine was prepared by transfection with pcDNA3 - hCEA using lipofectamine. CEA mRNA expressed in DCs (pcDNA3 - hCEA) was confirmed by RT - PCR , CEA expression level was detected with RIA method , and CEA specific CTL was induced in vitro. After vaccination of DCs(pcDNA3 -hCEA) , the survival time of the BALB/ c mice challenged with critical loading CT26 ( hCEA+ ) was observed. SULTS : G418 test showed that about 14 % DCs were transfected with pcDNA3 - hCEA. And CEA mRNA and protein could be detected respectively by RT - PCR and RIA in the genetically modified DCs. Furthermore , the DCs coud be targeted by specific CTL , the survival time of the mice challenged with CT26 ( hCEA+ ) was prolonged 1 - 4 weeks. CONCLUSION: These results demonstrate that specific antitumor immune responses could be induced efficiently by vaccination of DCs (pcDNA3 - hCEA) , which is transfected eukaryotic expression vector encoding tumor antigen gene.
Zhengzhou UniversityCheng, Henan Sheng, China