Dichloroacetate enhances the antitumor effect of pirarubicin via regulating the ROS-JNK signaling pathway in liver cancer cells

Aim: Liver cancer is one of the most common malignancies and has a high recurrence rate. However, current treatment strategies do not achieve satisfactory outcomes in the clinic. To explore a new strategy to enhance the effectiveness of chemotherapy in liver cancer, we investigated whether dichloroacetate (DCA) could enhance the sensitivity of liver cancer cells to pirarubicin (THP).

Methods: Liver cancer cells were treated with DCA alone, THP alone, or DCA and THP combined. Cell viability was determined by the CCK-8 assay. Cell apoptosis was analyzed by flow cytometer. Reactive oxygen species (ROS) were detected using a CM-H2DCFDA fluorescence probe. Protein levels were identified by immunoblotting.

Results: The results revealed that DCA significantly enhanced the antitumor effect of THP in liver cancer cells. Changes in morphology and adherence ability were observed, as well as decreased cell viability. The results of flow cytometry showed that the combination of THP and DCA significantly increased apoptosis of liver cancer cells. Moreover, compared with THP alone, combination treatment with DCA significantly increased THP-triggered ROS generation in liver cancer cells. The antioxidant N-acetyl-L-cysteine reversed the synergistic effect of DCA and THP on ROS generation, cell viability and apoptosis. Furthermore, phosphorylation of c-Jun N-terminal kinase (JNK) was significantly increased in the DCA and THP combination group. The effects of DCA and THP on cell viability and apoptosis were inhibited by the JNK inhibitor SP600125.

Conclusion: The results obtained in the present study indicated that DCA enhanced the antitumor effect of THP in liver cancer cells via regulating the ROS-JNK signaling pathway.

A feedback loop in PPARγ-adenosine A2A receptor signaling inhibits inflammation and attenuates lung damages in a mouse model of LPS-induced acute lung injury

Although peroxisome proliferator-activated receptor-γ (PPARγ) and adenosine A2A receptor (A2AR) are reported to be anti-inflammatory factors in acute lung injury (ALI), their internal link and synergic or antagonistic effect after activation are poorly understood. Here, we found that PPARγ and A2AR could upregulate the mRNA and protein expressions of each other in lung tissues of LPS-induced mouse ALI model and murine macrophages. Further investigation demonstrated that PPARγ upregulated A2AR expression by directly binding to a DR10 response element (-218 to -197) within A2AR gene promoter region. Instead of directly interacting with PPARγ, A2AR stimulated PPARγ expression via protein kinase A (PKA)-cAMP response element binding protein (CREB) signaling by provoking the binding of CREB to a cAMP responsive element (CRE)-like site in PPARγ gene promoter region. In addition, combination of PPARγ and A2AR agonists was found to exert obviously better effect on suppressing neutrophil infiltration and inflammatory cytokine expressions, attenuating lung edema, pathological changes and improving lung function of blood gas exchange than their single application. These findings reveal a novel functional positive feedback loop between PPARγ and A2AR signaling to potentialize their effect on inhibiting inflammation and attenuating lung damages in ALI. It suggests that targeting this PPARγ-A2AR signaling rather than PPARγ or A2AR alone may be a more attractive and efficient potential therapeutic strategy for ALI.

Upregulation of ski in fibroblast is implicated in the peroxisome proliferator--activated receptor δ-mediated wound healing

BACKGROUND/AIM

Both peroxisome proliferator-activated receptor (PPAR) δ and Ski are investigate the interaction of PPARδ and Ski and this interaction-associated effect in wound healing.

METHODS

Effect of PPARδ activation on Ski expression was detected in rat skin fibroblasts by real-time PCR and western blot. Luciferase assay, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay were performed to identify the binding site of PPARδ in the promoter region of rat Ski gene. And the functional activity of PPARδ regulation to Ski was detected in fibroblast proliferation and rat skin wound healing model.

RESULTS

PPARδ agonist GW501516 upregulated Ski expression in a dose-dependent manner. Direct repeat-1 (DR1) response element locating at -865∼-853 in Ski promoter region was identified to mediate PPARδ binding to Ski and associated induction of Ski. Furthermore, PPARδ upregulated Ski to promote fibroblasts proliferation and rat skin wound repair, which could be largely blocked by pre-treated with Ski RNA interference.

CONCLUSION

This study demonstrates that Ski is a novel target gene for PPARδ and upregulation of Ski to promote fibroblast proliferation is implicated in the PPARδ-mediated wound healing.

Panax notoginseng saponins attenuate atherosclerosis via reciprocal regulation of lipid metabolism and inflammation by inducing liver X receptor alpha expression

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng (Burk.) F.H. Chen has been used as a health product and natural remedy in traditional medicine for cardiovascular diseases for more than 1000 years in Asia, including China, Japan, and Korea. Panax notoginseng saponins (PNS) are the major effective ingredients extracted from Panax notoginseng.

AIM OF THE STUDY

The purpose of this study was to investigate whether Panax notoginseng saponins (PNS) attenuated atherosclerosis by inducing liver X receptor alpha (LXRα) expression and to elucidate the mechanisms responsible for the effects.

MATERIALS AND METHODS

The AS rats were treated once daily with PNS (100 mg/kg, i.p.), and pathological changes in the aorta were observed using Sudan IV staining. The expression of LXRα in the aortic wall was measured by Western blot analysis. THP-1 macrophages were cultured with PNS in the presence or absence of geranylgeranyl pyrophosphate ammonium salt (GGPP), an LXRα antagonist. The expression of LXRα and its target genes ATP-binding cassette A1 and G1 (ABCA1, ABCG1) were determined by qRT-PCR. The transcriptional activation of the LXRα gene promoter was analyzed by a reporter assay. The NF-κB DNA binding activity and the expression of interleukin (IL)-6, monocyte chemotactic protein-1 (MCP-1) was evaluated respectively by Trans-AM NF-κB ELISA and ELISA in THP-1 macrophages that were stimulated with LPS after treatment with PNS and GGPP.

RESULTS

PNS treatment alleviated the typical pathological changes associated with atherosclerosis in rats. The expression of LXRα was increased in rat aortas after treatment with PNS. In vitro, PNS increased LXRα mRNA levels in THP-1 macrophages. The reporter assays showed that PNS enhanced transcriptional activation of the LXRα gene promoter and led to the upregulation of ABCA1 and ABCG1 expression. This upregulation could be reversed by treatment with GGPP. Additionally, PNS inhibited NF-κB DNA binding activity and reduced secretion of IL-6 and MCP-1 in LPS-stimulated THP-1 macrophages. These effects could be reversed by GGPP.

CONCLUSIONS

The results indicated that the PNS-mediated attenuation of AS may, at least partly, due to LXRα uprergulation. The mechanisms of action included enhancement transcriptional activation of the LXRα gene promoter by PNS and subsequent upregulation of ABCA1 and ABCG1 and inhibition of NF-κB DNA binding activity.

Chronic or high dose acute caffeine treatment protects mice against oleic acid-induced acute lung injury via an adenosine A2A receptor-independent mechanism

The antagonism or genetic deletion of adenosine A(2A) receptors has been shown to exacerbate tissue damage in acute lung injury. Caffeine, a widely consumed behavioral drug, acts as a non-selective antagonist of A(2A) receptor and also has additional pharmacological effects. Thus, the protective vs. deleterious effects of caffeine in acute lung injury should be evaluated. In a murine oleic acid-induced model of acute lung injury, we found that chronic caffeine treatment by drinking water (0.1g/l or 0.25g/l for 2 weeks before acute lung injury) or acute caffeine treatment at high dose (i.p. 50mg/kg, injection, 30min before acute lung injury) significantly attenuated the lung edema, hemorrhage, neutrophil recruitment as well as the inflammatory cytokine tumor necrosis factor-α (TNF-α) and interleukin-1 (IL-1) expressions in both of the wild type (WT) and A(2A) receptor knockout (KO) mice. This profile was accompanied by increased cAMP levels and up-regulation of A2B receptor mRNAs in the lungs. In contrast, acute caffeine treatment at low dose (i.p. 5mg/kg or 15mg/kg, injection, 30min before acute lung injury) enhanced the inflammation and lung damage in WT mice with decreasing cAMP but not in A(2A) receptor KO mice. These results indicate that caffeine either enhances lung damage by antagonizing A(2A) receptor or exerts protection against lung damage via A(2A) receptor-independent mechanisms, depending on the timing of exposure (chronic vs. acute) and dose of administration (low vs. high). These findings provide new insight of caffeine in acute lung injury and highlight the potential benefit and strategy of caffeine intake or administration for preventing acute lung injury.

Complete atrioventricular block associated with dapsone therapy: a rare complication of dapsone-induced hypersensitivity syndrome

Dapsone is still widely used for a range of infectious and inflammatory diseases. A potential severe side-effect, known as dapsone-induced hypersensitivity syndrome (DHS), may occur. DHS is characterized by fever, skin rashes, lymphadenopathy and multiorgan dysfunction manifesting as hepatitis, cholangitis, pneumonitis, colitis, thyroiditis and myocarditis. However, DHS-associated complete atrioventricular block has not previously been reported. We describe here a 45-year-old Chinese woman who developed DHS after 5 weeks of dapsone therapy for pustular palmoplantar psoriasis. In addition to typical DHS symptoms, she experienced several episodes of syncope as a result of complete atrioventricular block which was successfully reversed with a permanent pacemaker implantation.

[Effect of androsterone on scavenger receptor class B type I in human vascular endothelial cells]

OBJECTIVE

To investigate the effect of FXR on scavenger receptor class B type I (SR-BI) expression.

METHODS

Human vascular endothelium Eahy926 cells were treated with FXR agonist androsterone, and the specific target gene of FXR SHP mRNA was detected by RT-PCR. SR-BI mRNA and protein were determined using RT-PCR, real-time PCR and Western blotting.

RESULTS

The level of SHP mRNA in Eahy926 cells increased after androsterone treatment at different concentrations for 24 h, demonstrating FXR activation in the cells. RT-PCR, real-time PCR and Western blotting detected increased SR-BI expression at both mRNA and protein levels after FXR activation.

CONCLUSION

FXR increases the expression of SR-BI in human vascular endothelium cells.

[Expression and activity analysis of human 67kD laminin receptor in Pichia pastoris]

To carry out the secretive expression of human 67 kD laminin receptor (67LR), recombinant expression plasmid pPIC9K-67LR was constructed by inserting of 67LR cDNA into yeast expression vector pPIC9K. The 67LR protein was expressed in Pichia pastoris after induced by methanol, and about 12.56 mg electrophoresis purity 67LR could be obtained after the purification of 1L culture using affinity chromatograph column. In vitro competitive binding assay showed that target protein has an excellent biological activity. The successful expression of 67LR has placed a solid foundation for the research on structure and functions of 67LR.

[Expression of human LNalpha4LG4-5 in Pichia yeast]

To carry out the secretive expression of human laminin alpha4 chain LG4-5 module (hLNalpha4LG4-5), recombinant expression plasmid pPICZalphaA-LG45 was constructed by inserting of hLNalpha4LG4-5 cDNA into yeast expression vector pPICZaA. The hLNalpha4LG4-5 protein was expressed in GS115 Pichia yeast strain after induced by methanol, and purified target protein can obviously promote the expansion and adhesion of 293 cells.

[The cloning, high level expression in Escherichia coli of human beta-defensin 3 and its antimicrobial activity analysis]

In recent years, Bacterial resistance is more and more serious for the irrational use of antibiotics produces resistant strains and other reasons. Human are trying to solve the problem from different ways, including the study of antimicrobial peptides. Defensin is one of the most important of antimicrobial peptides. A novel antimicrobial peptide, human beta-defensin 3, was isolated and demonstrated a salt-insensitive broad spectrum of potent antimicrobial activity against many potentially pathogenic microbes. The total RNA was extracted from human tonsil and the hbetaD-3 specific cDNA sequence was amplified with RT-PCR. After sequenced, the target DNA fragment was cloned into pQE-80L vector together with the DNA fragment encoding carrier protein DHFR. The recombinant vectors were transformed into E. coli M15 and the expression was induced based on the optimal values of the IPTG concentration incubation temperature and induction time determined in the previous section. The expressed proteins were analyzed by SDS-PAGE and Western-blotting. The mass of the recombinant protein was about 40% of total bacteria protein. Isolate and purify the target protein. The recombinant hbetaD-3 fusion proteins possess the antimicrobial activity to staphylococcus aureus, multiresistant staphylococcus aureus (only vancomycin-sensitive) and Candida albicans in the assay of drug susceptibility. Advanced study can be continued based on our experiments.

Screening and identification of mimotope of gastric cancer associated antigen MGb1-Ag

AIM: Using a monoclonal antibody against gastric cancer antigen named MGb1 to screen a phage-displayed random peptide library fused with coat protein pIII in order to get some information on mimotopes.

METHODS: Through affinity enrichment and ELISA screening, positive clones of phages were amplified. 10 phage clones were selected after three rounds of biopanning and the ability of specific binding of the positive phage clones to MGb1-Ab were detected by ELISA assay (DNA sequencing was performed and the amino acid sequences were deduced) By blocking test, specificity of the mimic phage epitopes was identified.

RESULTS: There were approximately 200 times of enrichment about the titer of bound phages after three rounds of biopanning procedures. DNA of 10 phage clones after the third biopanning was assayed and the result showed that the positive clones had a specific binding activity to MGb1-Ab and a weak ability of binding to control mAb or to mouse IgG. DNA sequencing of 10 phage clones was performed and the amino acid sequences were deduced. According to the homology of the amino acid sequences of the displayed peptides, most of the phage clones had motifs of H(x)Q or L(x)S. And these 10 phage clones could also partly inhibit the binding of MGb1-Ab to gastric cancer cell KATO-III. The percentage of blocking was from (21.0 ± 1.6)% to (39.0 ± 2.7)%.

CONCLUSION: Motifs of H(x)Q and L(x)S selected and identified show a high homology in the mimic epitopes of gastric cancer associated antigen. There may be one or more clones which can act as candidates of tumor vaccines.

Identification of tumor associated single-chain Fv by panning and screening antibody phage library using tumor cells

AIM: To study the feasibility of panning and screening phage-displaying recombinant single-chain variable fragment (ScFv) of anti-tumor monoclonal antibodies for fixed whole cells as the carriers of mAb-binding antigens.

METHODS: The recombinant phage displaying libraries for anti-colorectal tumor mAb MC3Ab, MC5Ab and anti-gastric tumor mAb MGD1 was constructed. Panning and screening were carried out by means of modified fixation of colorectal and gastric tumor cells expressed the mAb-binding antigens. Concordance of binding specificity to tumor cells between phage clones and parent antibodies was analyzed. The phage of positive clones was identified with competitive ELISA, and infected by E. coli HB2151 to express soluble ScFv.

RESULTS: The ratio of positive clones to MC3-ScF-MC5-ScFv and MGD1-ScFv were 60%, 24% and 30%. MC3-ScFv had M_r 32000 confirmed by Western blot. The specificity to antigen had no difference between 4 positive recombinant phage antibodies and MC3Ab.

CONCLUSION: The modified process of fixing whole tumor cells is efficient, convenient and feasible to pan and screen the phage-displaying ScFv of anti-tumor monoclonal antibodies.

Expression and identification of recombinant soluble single-chain variable fragment of monoclonal antibody MC3

AIM: To generate soluble single chain variable fragments (ScFv) of monoclonal antibody MC3 recognizing colorectal and gastric carcinomas.

METHODS: mRNA was isolated from the hybridoma cell line producing MC3 and the DNAs encoding variable domains of heavy and light chains (VH and VL) of the antibody were amplified separately by RT-PCR and assembled into ScFv DNA with a linker DNA.The ScFv DNA was ligated into the phagemid vector pCANTAB5E and the ligated sample was transformed into E. coli TG1.The transformed cells were infected with M13KO7 helper phage to yield recombinant phages. After two rounds of panning with gastric carcinoma cell line AGS highly expressing MC3-binding antigen, the phage clones displaying ScFv fragments of the antibody were selected by ELISA. 4 phage clones showing strong signal in ELISA were used to infect E. coli HB2151 to express soluble ScFvs. The soluble ScFvs were identified by Dot blot and Western blot, and their antigen-binding activity was assayed by ELISA. The VH and VL DNAs of the ScFv DNA derived from phage clone 19 were sequenced.

RESULTS: The VH, VL and ScFv DNAs were about 340 bp, 320 bp and 750 bp respectively. After two rounds of panning to the recombinant phages, 18 antigen-positive phage clones were selected from 30 preselected phage clones by ELISA. All the soluble ScFvs derived from the 4 out of the 18 antigen-positive phage clones were about M_r32000 and concentrated in periplasmatic space under the given culture condition. The soluble ScFvs could bind the antigen, and they shared the same binding site with MC3. The sequences of the VH and VL DNAs of the MC3 ScFv showed that the variable antibody genes belonged to the IgG1 subgroup, κ-type.

CONCLUSION: The soluble ScFv of MC3 is successfully produced, which not only provides a possible novel targeting vehicle for in vivo and in vitro study on associated cancers, but also offers the anuibody a stable genetic source.

Molecular analyses of a repetitive DNA sequence in wheat (Triticum aestivum L.)

A repetitive sequence designated WE35 was isolated from wheat genomic DNA. This sequence consists of a 320-bp repeat unit and represents approximately 0.002% of the total wheat DNA. It is unidirectionally distributed either continuously or discretely in the genome. Ladder-like banding patterns were observed in Southern blots when the wheat genomic DNA was restricted with endonuclease enzymes EcoRI, HincII, NciI, and NdeI, which is characteristic for tandemly organized sequences. Two DNA fragments in p451 were frequently associated with the WE35 repetitive unit in a majority of lambda wheat genomic clones. A 475-bp fragment homologous to the 5'-end long terminal repeat (LTR) of cereal retroelements was also found in some lambda wheat genomic clones containing the repetitive unit. Physical mapping by fluorescence in situ hybridization (FISH) indicated that one pair of wheat chromosomes could be specifically detected with the WE35 positive probe p551. WE35 can be considered a chromosome-specific repetitive sequence. This repetitive unit could be used as a molecular marker for genetic, phylogenetic, and evolutionary studies in the tribe Triticeae.

Cloning and identification of an angiostatic molecule IP-10/crg-2

AIM: To obtain human and murine cDNAs encoding IFN-γ inducible protein 10 (IP-10) and cytokine responsive gene-2 (Crg-2).

METHODS: The encoding genes of IP-10 and Crg-2 were amplified by RT-PCR from cultured human fibroblast cells and Balb/c mouse liver treated by IFN-γ and TNF-α , respectively, and cloned into plasmids of pUC19 and pGEM3Zf(+).

RESULTS: The nucleotide sequences of the amplified DNA were confirmed by endonucleases digestion and sequencing.

CONCLUSION: Recombinant IP-10/crg-2 gene clones with 306 bp and 314 bp inserts were established for further research on biological activities and ligands of hIP-10/mCrg-2