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Biomedical subjects

Liu Hong

Publications and source records attributed to Liu Hong.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Effect of exogenous RGS16 gene transfection on growth of glioma cell line C6].

BACKGROUND & OBJECTIVE: Wild type p53 could induce RGS16 mRNA expression, and RGS16 protein is related with carcinogenesis of glioma. This study was designed to investigate the effects of exogenous RGS16 gene transfection on the growth of rat glioma cell line C6. METHODS: A eukaryotic expression plasmid pIRES2-EGFP-RGS16 was constructed, and transfected into C6 cells. The cells were selected by G418. The expression of enhanced green fluorescent protein (EGFP) was observed under fluorescent microscope, and the expression of RGS16 mRNA and protein was detected by reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry. The effects of RGS16 gene on cell cycle progression, cell growth, and proliferation of C6 cells were measured by flow cytometry, cell growth curve, and clonogenic assay in plate. RESULTS: C6-RGS16 and C6-GFP cells, which separately expressed RGS16 and pIRES2-EGFP vector, were constructed successfully. S phase proportion was significantly higher in C6-RGS16 cells than in C6-GFP and C6 cells (28.5% vs. 18.9% and 14.3%, P<0.05); C6-RGS16 cells grew faster than C6-GFP and C6 cells. The clone formation rate was significantly lower in C6-RGS16 cells than in C6-GFP and C6 cells (12% vs. 25% and 25%, P<0.05). CONCLUSION: Exogenous RGS16 gene could promote cell cycle progression of glioma C6 cells from G1 phase to S phase, and accelerate cell growth, but can't increase the clone formation.

Animals↗
PubMed2005

Expression of delayed rectifier potassium channels and their possible roles in proliferation of human gastric cancer cells.

Voltage-gated potassium (Kv) channels have been reported to be involved in the proliferation of many types of cells, including tumor cells. The overexpression of the Kv channels and related channel activity are involved in the neoplastic process. Our previous study has shown the existence of delayed rectifier potassium (I(K)) current in gastric cancer cells SGC7901. However, the expression and function of most delayed rectifier potassium (K(D)) channel subunits in gastric cancer cells are not completely resolved. Here we examine expression of K(D) channel subunits in Kv1-Kv3 families in immortalized gastric epithelial cells GES and various gastric cancer cells (including AGS, KATOIII, MKN28, MKN45, MGC803, SGC7901, SGC7901/ADR and SGC7901/VCR), and their roles in cell proliferation. RT-PCR analysis reveals that all cell lines examined express Kv1.3, Kv1.5, Kv1.6, Kv2.1 and Kv2.2. However, Kv1.2 and Kv3.2 genes are barely detectable in any given cancer cell lines. Kv1.5 protein, high mRNA levels in all cell lines examined, is also expressed in some cancer cells lines and more frequently detected in gastric cancer tissues. Downregulation of the expression of Kv1.5 in SGC7901 with RNA interference significantly inhibited the proliferation and tumorigenicity of SGC7901 cells. Moreover, in Ca(2+)-containing rather than Ca(2+)-free medium, KCl (50mM) stimulated a rapid increase in the concentration of cytosolic calcium in empty vector transfected cells that was blocked by verapamil. Likewise, decrease the expression of Kv1.5 with short interfering RNA also blocked the depolarization-induced influx of Ca(2+). This finding suggests that more than one kind of K(D) channel subunits are expressed in various gastric cancer cell lines. Kv1.5 may be involved in tumor cells proliferation by controlling Ca(2+) entry, and the interference of K(D) channels expression and/or activity could provide a novel strategy to reverse the malignant phenotype of gastric cancer cells.

Calcium↗
PubMed2005

Expressions and clinical significances of angiopoietin-1, -2 and Tie2 in human gastric cancer.

The roles of angiopoietins in gastric cancer progression are still not fully understood. In this study the expressions of angiopoietin-1 (Ang-1), -2 (Ang-2) were compared by immunohistochemistry in 53 gastric cancer and 23 normal gastric mucosa samples. Results revealed that Ang-2 expression was significantly increased in gastric cancer tissues (74%) and was correlated with higher TNM stage, lymph node metastasis as well as distance metastasis. The expression of Ang-1 was also elevated in cancerous tissues (66%) and significantly associated with differentiation degree. In addition, Ang-2 as well as its receptor Tie2 expressions were higher in 12 pairs of gastric cancer tissue samples than those in corresponding adjacent samples by Western blot, while Ang-1 expression showed great heterogeneity. Furthermore, the expressions of Ang-1 and Ang-2 were almost positive in eight gastric cancer cell lines. Among them, AGS expressed both Ang-2 and a relatively moderate amount of Ang-2(443), a novel splice form of Ang-2, while others showed only Ang-2 mRNA expression.

Angiopoietin-1↗
PubMed2005

The potent inhibitory effects of cisapride, a specific blocker for human ether-a-go-go-related gene (HERG) channel, on gastric cancer cells.

BACKGROUND: Ion channels may play a role in carcinogenesis. Human ether-a-go-go-related gene (HERG) encoding one of the components of delayed rectifier potassium currents has been indicated to be involved in tumor cell growth and death. Our aim is to investigate the effects of cisapride, a specific blocker for HERG channel, on human gastric cancer cells. METHODS: The effects of cisapride on the proliferation, clonogenicity, cell cycle and apoptosis of gastric cancer cells were evaluated by MTT assay, clonogenicity assay, flow cytometry and transmission electron microscopy. The expression of HERG mRNA and protein in gastric cancer cells and tissues was measured by RT-PCR, Western blot and immunohistochemistry, respectively. RESULTS: HERG mRNA and protein were exclusively expressed in gastric cancer cells. The HERG protein was localized in the cytoplasm and membrane of the gastric cancer cells. The proliferation of gastric cancer cells expressing HERG protein was inhibited in a time- and dose-dependent manner when treated with cisapride (P<0.05). The clonogenicity of gastric cancer cells treated with cisapride (100 nM) was reduced (P<0.05). Flow cytometric analysis indicated that cisapride tends to inhibit gastric cancer cells entering S phase from G(1) phase in the cell cycle (P<0.05). Apoptotic cells were found increased in gastric cancer cells treated with cisapride by both flow cytometry and electron microscopy. CONCLUSIONS: As HERG channel blocker, cisapride, can inhibit the growth of gastric cancer cells by altering distribution of cell cycle and inducing apoptosis so as to be of potential value in the treatment of gastric cancer.

Antineoplastic Agents↗
PubMed2005

Enhanced immune response to gastric cancer specific antigen Peptide by coencapsulation with CpG oligodeoxynucleotides in nanoemulsion.

CpG oligodeoxynucleotides (CpG ODN) have been shown to have potent adjuvant activity for a wide range of antigens. Of particular interest is their improved activity when closely associated with the antigen. The purpose of this study is to construct a nanovaccine coencapsulated with a gastric cancer specific antigen MG7 mimotope peptide and adjuvant CpG ODN 1645 using new nanotechnology as nanoemulsion and evaluate its immunocompetence. Nanoemulsion vaccine was prepared using magnetic ultrasound methods. BALB/c mice were immunized and the in vivo effectiveness was evaluated using tumor challenge assay. It was shown that the tumor masses formed in the mice immunized with coencapsulated nanovaccine (0.0825 g) markedly smaller (P < 0.01) than those formed in the mice immunized with nanovaccine encapsulated with antigen peptide alone (0.4465 g). A tumor inhibiting rate as high as 82.5% of the coencapsulated nanovaccine was obtained, while nanovaccine encapsulated with peptide only could not achieve the same effect (28.5%) (P < 0.01). Enzyme-linked immunospot assay (ELISPOT) showed that immunization using MG7 mimotope peptide coencapsulated with CpG ODN within the same nanoemulsion enhanced the frequency of splenocytes secreting IFN-gamma significantly (P < 0.01) when compared with immunization using MG7 peptide encapsulated in nanoemulsion alone (197spots/1 x 10(6) vs. 73 spots/1 x 10(6)). Cellular ELISA indicated that serum titer of antibody against MG7-Ag was significantly higher (P < 0.01) in mice immunized with coencapsulation form nanovaccine (0.7884) than that in the group immunized with nanovaccine encapsulated with MG7 peptide alone (0.3616). Using intracellular flow cytometric analysis, it was found that the IFN-gamma response was contributed by CD4+ T-cells. Our experiments suggest that a vaccinal approach using nano-delivery system carrying in tumoral epitope and CpG ODN as adjuvant may have important implications for cancer therapy.

Animals↗
PubMed2005

ZNRD1 gene suppresses cell proliferation through cell cycle arrest in G1 phase.

ZNRD1, a transcription-associated gene, was recently found in our laboratory significantly suppress the cell proliferation of stomach cancer cells in vitro and in vivo. In this study, we firstly characterized ZNRD1 expression in a wide spectrum of gastric diseases by immunohistochemistry and RT-PCR. We also investigated its antiproliferative effects and associated molecular alterations in human gastric cancer cell line AGS and mouse fibroblast cell line NIH3T3. Anti-ZNRD1 monoclonal antibody H6 was found to react with 38 (63%) of normal gastric tissues, and 51 (81%) of gastritis. In contrast, no positive expression was found in gastric adenocarcinomas. Thus, the expression of ZNRD1 in normal gastric tissues was significantly higher than that in gastric adenocarcinomas. Compared with the control clones, ZNRD1-transfected cells exhibited significant inhibition of cell growth with G1 cell cycle arrest mediated by the suppression of cyclin D1 expression. These results showed that ZNRD1 may play an important role in the regulation of gastric carcinogenesis and could be used as a new target in treatment of stomach cancer.

Adenocarcinoma↗
PubMed2005

Ex vivo adipose tissue engineering by human marrow stromal cell seeded gelatin sponge.

The limitation of current clinical treatment for restoration extended defects of soft tissue associated with trauma, tumor resections, and congenital deformities are well known. This study demonstrates that human bone marrow stromal cells (MSCs) can be utilized to tissue engineer adipose tissue for therapeutic purposes. Adipogenic potentials of monolayer-cultured human MSCs were evaluated by biochemical measurement of an adipogenic differentiation marker (glycerol-3-phosphate dehydrogenase, G-3-PDH) and cellular morphology. After preparation by seeding human MSCs on a 3-dimensional gelatin sponge and exposure to adipogenic differentiation medium, the ex vivo tissue-engineered adipose constructs were assessed histomorphologically and biochemically. Lipid droplets accumulated and expanded within the constructs accompanied by a significant increase of G-3-PDH activity. The present study indicates that bone MSCs could be a cell resource in tissue engineering adipose tissue, while gelatin sponge could be a good scaffold in this approach to improve the outcome of clinical treatment.

Adipose Tissue↗
PubMed2005

Zinc ribbon domain-containing 1 (ZNRD1) mediates multidrug resistance of leukemia cells through regulation of P-glycoprotein and Bcl-2.

Here, we investigated the role of zinc ribbon domain-containing 1 (ZNRD1) in multidrug resistance (MDR) of leukemia cells and the possible underlying mechanisms. ZNRD1 was found overexpressed in the vincristine-induced MDR leukemia cell HL-60/vincristine moreso than its parental cell HL-60. Up-regulation of ZNRD1 expression could confer resistance of both P-glycoprotein (P-gp)-related and P-gp-nonrelated drugs on HL-60 cells and suppress Adriamycin-induced apoptosis accompanied by decreased accumulation and increased releasing amount of Adriamycin. ZNRD1 could significantly up-regulate the expression of P-gp, Bcl-2, and the transcription of the MDR1 gene but not alter the expression of MDR-associated protein, glutathione S-transferase activity, or intracellular glutathione content in leukemia cells. In addition, inhibition of ZNRD1 expression by RNA interference or P-gp inhibitor could partially reverse ZNRD1-mediated MDR. The further study of the biological functions of ZNRD1 may be helpful for understanding the mechanisms of MDR of leukemia and developing possible strategies to treat leukemia.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Effect of transforming growth factor-beta1 on bone regeneration in critical-sized bone defects after irradiation of host tissues.

OBJECTIVE: To determine whether sustained release of transforming growth factor (TGF)-beta1 from a gelatin hydrogel would enhance bone regeneration in critical-sized long-bone defects and overcome inhibitory effects of preoperative irradiation. ANIMALS: 24 adult New Zealand White rabbits. PROCEDURE: Rabbits were allocated to 2 groups. Twelve rabbits received localized megavoltage radiation to the right ulna by use of a cobalt 60 teletherapy unit, and 12 rabbits received no irradiation. Then, a 1.5-cm defect was aseptically created in the right ulna of each rabbit. Gelatin hydrogel that contained 5 microg of adsorbed recombinant-human (rh)TGF-beta1 was placed in the defect of 12 rabbits (6 irradiated and 6 nonirradiated), and the other 12 rabbits received hydrogel without rhTGF-beta1. Rabbits were euthanatized 10 weeks after surgery. New bone formation within the defect was analyzed by use of nondecalcified histomorphometric methods. A 1-way ANOVA was used to compare differences among groups. RESULTS: New bone formation within the defect was significantly greater in TGF-beta1-treated rabbits than in rabbits treated with hydrogel carrier alone. Local delivery of rhTGF-beta1 via a hydrogel carrier in irradiated defects resulted in amounts of bone formation similar to those for nonirradiated defects treated by use of rhTGF-beta1. CONCLUSIONS AND CLINICAL RELEVANCE: Local delivery of TGF-beta1 by use of a hydrogel carrier appears to have therapeutic potential for enhancing bone formation in animals after radiation treatments. IMPACT FOR HUMAN MEDICINE: This technique may be of value for treating human patients at risk for delayed bone healing because of prior radiation therapy.

Administration, Topical↗
PubMed2005

[Position and orientation of zygomatic-area implant of zygo-buccal flange osseointegrated implant obturator].

OBJECTIVE: To provide objective data for position and orientation of zygomatic-area implant used in zygo-buccal flange osseointegrated implant obturator for patients with large maxillary defect. METHODS: Fifty cases of normal unilateral zygomatic body with dentition were measured on three-dimensional spiral CT images. Measurements included the slope angle of zygomatic body on sagittal sectional image, the maximal horizontal distance from the buccal boundary of maxillary alveolar to outboard of maxillary sinus. Furthermore, the configuration of zygomatic body was observed on coronal sectional image. RESULTS: The average rearward slope angle of zygomatic-body was 80.03 degrees. Forty-eight cases showed straight zygomatic-body configurations and two cases quite curvy. The maximal horizontal distance from the buccal boundary of maxillary alveolar to outboard of maxillary sinus was 6.77 mm. CONCLUSIONS: In a normal condition, implants can be upright inserted tilting about 10 degrees ahead to utilize much zygomatic bone-volume in high site. In order to improve security and validity of implantation, it is better to take spiral CT examination to evaluate the bone volume and shape of zygomatic body before zygomatic-area implant.

Adolescent↗
PubMed2005

[Reversion of multidrug resistance in HL-60/VCR cells by down-regulation of bcl-2 with bcl-2 siRNA].

To evaluate the feasibility of gene therapy using bcl-2 as target in multiple drug resistance of leukemia, the small interfering RNA eukaryotic expression vector specific to human bcl-2 gene was constructed by gene recombination, then transfected into HL-60/VCR cells. Stable transfectants were obtained by G418 screening. The growth curve and drug sensitivity were detected by using MTT. The expression of Bax and ZNRD1 was analyzed by Western blot. The results showed that mU6pro-bcl-2 siRNA was successfully constructed and transfected into HL-60/VCR cells. The IC(50) of transfected cells to vincristine and adriamycin was significantly reduced as compared with that of the control. The expression of ZNRD1 in transfected cells was decreased as compared with that of the control, while Bax not. It is concluded that the bcl-2 siRNA restores the sensitivity of HL-60/VCR cells to conventional chemotherapeutic agents to a certain degree.

Blotting, Western↗
PubMed2004

Characterization of a specific phage-displayed Peptide binding to vasculature of human gastric cancer.

Antivascular therapy provides a promising method for anticancer therapy. But targeting to gastric cancer vessels is nonselective due in part to the lack of specific cell-surface receptors identified on target vascular cells. Herein we used in vivo screening of phage displayed peptide library to identify some peptides that bind selectively to endothelial cells of human gastric cancer rather than nonendothelial cells. After four rounds of selection, one phage was obtained with a cyclic 7-mer peptide CGNSNPKSC homing to human gastric adenocarcinoma . There was a 4.6 approximately 137.26-fold increase in the number of the selected phage in gastric cancer xenograft in comparision with control organs brain, heart, liver, spleen and kidney. Immunohistochemistry in mouse and human tissue showed that this phage peptide only bind to the endothelial cells of human gastric cancer. This peptide was observed only specific binding to HUVEC not to SGC-7901, Eca-109, LoVo and Hep-G2 by ELISA. The competitive and inhibitory result between the synthetic CGNSNPKSC peptide and the phage displaying the peptide CGNSNPKSC on HUVEC and in vivo was also confirmed its specific binding effect. This peptide may be a possible candidate for targeted drug delivery in antivascular therapy.

Angiogenesis Inhibitors↗
PubMed2004

Expression and significances of Id1 helix-loop-helix protein overexpression in gastric cancer.

The Id family of helix-loop-helix proteins is involved in a variety of biological processes, including development,proliferation, and angiogenesis. There is emerging evidence for deregulation of Id proteins in some cancers. Hence we determined Id expression in gastric cancer. To elucidate the involvement of Idl in gastric carcinogenesis, Immunohistochemistry was carried out on paraffin-embedded gastric cancer sections. By analyzing the relationship between the Idl staining index of individual tumors and the patient's clinical parameters, including histological grade, clinical stage, and presence of metastases, we found that strong Idl expression was associated with poorer differentiation and more aggressive behavior of tumor cells. To further explore Idl expression in human gastric carcinomas, Western blot analysis was performed to analyze Idl protein expression in 15 pairs of gastric tissues and cancers and in gastric cell lines. Idl was found to be expressed at higher levels in 11/15 cancer tissues compared to adjacent tissues. Idl was upregulated more prominently in the poorly differentiated cell lines than in the well-differentiated ones. Semiquantitative RT-PCR was carried out to investigate the expression of mRNA of Idl in gastric cancer cell lines and it was upregulated in most of them. Our results demonstrate that Idl protein may play an important role in the process of gastric carcinogenesis and high-level Id I expression may be related to the malignant potential of tumor cells.

Adult↗
PubMed2004

Suppression of the cell proliferation in stomach cancer cells by the ZNRD1 gene.

Zinc ribbon domain-containing 1 (ZNRD1), a transcription-associated gene, was recently found to be downregulated in human gastric cancer tissues as compared to the matched adjacent nonneoplastic tissues. In this study, we constructed the siRNA eukaryotic expression vectors of ZNRD1 and transfected them into normal gastric epithelial cells (GES-1). We also introduced the ZNRD1 gene into gastric cancer cells that do (SGC7901) and do not (AGS) express ZNRD1 endogenously. GES-1 cells stably transfected with the ZNRD1-RNAi were found to exhibit significantly quicker proliferation than empty vector transfectants. AGS cells stably transfected with the ZNRD1 cDNA exhibited significantly decreased growth rate as compared to control vector transfectants, whereas SGC7901 cells did not. Furthermore, ZNRD1 suppresses growth of AGS cells in soft agar and tumor formation in athymic nude mice. This study clearly demonstrates that ZNRD1 may play an important role in the control of human gastric cancer development by regulating cell proliferation. These results provide new insights into the function of ZNRD1 and further validate ZNRD1 as a potential therapeutic target in gastric cancer.

Animals↗
PubMed2004

Reversal of multidrug resistance of gastric cancer cells by downregulation of TSG101 with TSG101siRNA.

We have previously identified tumor susceptibility gene101 (TSG101), overexpressed in vincristine-resistant human gastric adenocarcinoma cell line SGC7901/VCR using a modified subtractive hybridization method and Western blot. In the present study, we constructed two siRNA eukaryotic expression vectors of TSG101 and transfected them into SGC7901/VCR cells to examine whether the down-regulation of TSG101 increased cell sensitivity towards chemotherapeutic drugs. After transfection, the expression of TSG101 was dramatically decreased in TSG101 siRNA transfectants compared with that in parental cells and empty vector control cells. The down-regulation of TSG101 could significantly enhance the sensitivity of SGC7901/VCR cells to vincristine and adriamycin. The capacity of cells to efflux adriamycin markedly decreased in TSG101 siRNA transfectants. These observations suggested that the siRNA constructs of TSG101 we made could effectively down-regulate the expression of TSG101 and reverse the resistant phenotype of gastric cancer cells. The preliminary study suggested that TSG101 might play an important role in multidrug resistance of gastric carcinoma.

Antineoplastic Agents↗
PubMed2004

Overexpression of ZNRD1 promotes multidrug-resistant phenotype of gastric cancer cells through upregulation of P-glycoprotein.

ZNRD1, a new zinc ribbon gene, has been previously identified as an upregulated gene in a multidrug-resistant gastric cancer cell line SGC7901/VCR comparing to its parental cell SGC7901 by subtractive hybridization and RT-PCR. The antisense nucleic acid for ZNRD1 could enhance adriamycin accumulation in SGC7901/VCR cells and sensitize SGC7901/VCR cells to vincristine. The present study aims to explore the role of ZNRD1 in multidrug resistance in gastric cancer cells. Upregulation of ZNRD1 protein in SGC7901/VCR cells was confirmed by Western blot and immunocytochmical staining. ZNRD1 was genetically overexpressed in SGC7901 cells by gene transfection. It was found that overexpression of ZNRD1 could sensitize SGC7901 cells to P-glycoprotein (P-gp)-related anticancer drugs (vincristine, adriamycin, etoposide) but not to P-gp-nonrelated drugs (5-fluorouracil and cisplatin), which was accompanied with significantly decreased adriamycin accumulation and retention and increased adriamycin releasing in SGC7901 cells. Verapamil, an inhibitor for P-gp, could reverse the effects of ZNRD1 on drug sensitivity and drug accumulation in SGC7901 cells to a great extent. Western blot and Northern blot revealed that overexpression of ZNRD1 could upregulate P-gp at both protein and mRNA levels. Together, these results suggest that overexpression of ZNRD1 could promote multidrug-resistant phenotype of gastric cancer cells through upregulation of P-gp.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Adult stem cell driven genesis of human-shaped articular condyle.

Uniform design of synovial articulations across mammalian species is challenged by their common susceptibility to joint degeneration. The present study was designed to investigate the possibility of creating human-shaped articular condyles by rat bone marrow-derived mesenchymal stem cells (MSCs) encapsulated in a biocompatible poly(ethylene glycol)-based hydrogel. Rat MSCs were harvested, expanded in culture, and treated with either chondrogenic or osteogenic supplements. Rat MSC-derived chondrogenic and osteogenic cells were loaded in hydrogel suspensions in two stratified and yet integrated hydrogel layers that were sequentially photopolymerized in a human condylar mold. Harvested articular condyles from 4-week in vivo implantation demonstrated stratified layers of chondrogenesis and osteogenesis. Parallel in vitro experiments using goat and rat MSCs corroborated in vivo data by demonstrating the expression of chondrogenic and osteogenic markers by biochemical and mRNA analyses. Ex vivo incubated goat MSC-derived chondral constructs contained cartilage-related glycosaminoglycans and collagen. By contrast, goat MSC-derived osteogenic constructs expressed alkaline phosphatase and osteonectin genes, and showed escalating calcium content over time. Rat MSC-derived osteogenic constructs were stiffer than rat MSC-derived chondrogenic constructs upon nanoindentation with atomic force microscopy. These findings may serve as a primitive proof of concept for ultimate tissue-engineered replacement of degenerated articular condyles via a single population of adult mesenchymal stem cells.

Animals↗