Yuan-Hui Luo

Infrequent loss of heterozygosity of APC/MCC and DCC genes in gastric cancer showing DNA microsatellite instability.

AIM: To investigate the role of DNA microsatellite instability (MSI) in gastric carcinogenesis by studying associations between MSI status, clinicopathological features, and loss of genetic loci. METHODS: Six microsatellite loci and loss of heterozygosity at APC, DCC, and MCC were analysed by polymerase chain reaction based methods in 53 cases of advanced gastric cancer. RESULTS: MSI was observed in 32.1% of gastric carcinomas (17/53) and 20% of foci of intestinal metaplasia (3/15). Seven gastric carcinomas (13.7%) were MSI-high (MSI-H) (three loci or more) and 10 (18.9%) were MSI-low (MSI-L) (one or two loci). The frequency of MSI-H was higher in intestinal (25.0%) than in diffuse carcinomas (3.7%) (p < 0.05). None of the MSI-H tumours showed loss of heterozygosity at APC, MCC, or DCC loci. CONCLUSIONS: MSI may have an important and early role in a subset of gastric cancers, particularly the intestinal type. The MSI-H subset of gastric cancer has features in common with its colorectal counterpart, whereas MSI-L and microsatellite stable cancers appear to develop through the loss of heterozygosity pathway.

KAI1 gene suppresses invasion and metastasis of hepatocellular carcinoma MHCC97‐H cells in vitro and in animal models

Background: Downregulation of KAI1 gene expression has been found in many types of cancer cells and is closely related to cancer invasion and metastasis. This study was aimed at investigating the effects and possible underlying mechanisms of KAI1 gene on invasion and metastasis of human hepatocellular carcinoma (HCC).

Alterations of telomerase activity and terminal restriction fragment in gastric cancer and its premalignant lesions

Aims: In order to explore the role of alterations of telomerase activity and terminal restriction fragment (TRF) length in the development and progression of gastric cancer.

Detection of telomerase activity in biopsy samples of colorectal cancer

Background: Telomerase is a ribonucleoprotein that synthesizes telomeric DNA onto chromosomal ends. The expression of telomerase is thought to be required for cellular immortality and oncogenesis.

Dendritic Cells Reconstituted with a Human Heparanase Gene Induce Potent Cytotoxic T-Cell Responses against Gastric Tumor Cells in vitro

Background and Aims: Dendritic cell-based tumor vaccination is a promising approach in the treatment of cancer. Strategies to modify dendritic cells (DCs) with tumor-associated antigens (TAAs) can elicit specific immune responses against tumors. Heparanase is overexpressed in gastric cancer, especially in invasive and metastatic cells, but is downregulated in differential normal tissue. Therefore, heparanase is a potential target in immunotherapy for patients with advanced gastric cancer who are not candidates for surgery. The present paper was designed to investigate the immune response of a heparanase gene-modified DC-based vaccine against gastric cancer cell lines in vitro. Methods: DCs from peripheral blood mononuclear cells of healthy HLA-A2-positive donors were transfected with recombinant adenovirus containing the full-length cDNA of heparanase (rAd-Hpa) to generate heparanase gene-modified DC vaccine. T lymphocytes from the same donors were repeatedly activated by genetically modified DC vaccine to generate heparanase-specific cytotoxicity T lymphocytes (CTLs). CTL-mediated cell lysis of gastric cancer cells lines (KATO-III and SGC-7901) was analyzed in vitro by a standard 51Cr releasing assay. IFN-γ secretion was measured by ELISA in heparanase-specific CTLs cocultured with those gastric cancer cell lines. Results: Our results showed that the expression of heparanase in DCs transfected with rAd-Hpa was significantly increased.Furthermore, DCs transfected with rAd-Hpa could induce heparanase-specific CTLs against HLA-matched and heparanase-positive gastric cancer cells in vitro, while there were no killing effects on autologous lymphocytes. Meanwhile, these rAd-Hpa-modified DCs could increase IFN-γ secretion of effector cells when cocultured with KATO-III cells. Conclusions: These findings demonstrate for the first time that the transduction of DCs with rAd-Hpa can induce CTLs that specifically lyse heparanase-positive gastric cancer cells and increase IFN-γ secretion in an MHC-restricted fashion. Heparanase gene-modified DC vaccine offers a great opportunity for immunotherapy in patients with advanced gastric cancer and possibly also with other malignancies.

Antisense human telomerase reverse transcriptase could partially reverse malignant phenotypes of gastric carcinoma cell line in vitro.

Telomerase activity is detected in more than 90% of examined tumors but not in most normal somatic cells. Among three subunits of human telomerase, human telomerase reverse transcriptase (hTERT) is the rate-limiting component for telomerase activity. Therefore, targeting hTERT represents a promising approach for diminishing telomerase function that will probably not cause substantial side effects on telomerase negative somatic cells. To explore the effects of antisense hTERT (ahTERT) on the malignant phenotypes of human SGC-7901 gastric cancer cell line in vitro, an antisense eukaryotic expression vector of hTERT was constructed by gene recombinant technology. Telomerase activity by telomeric repeat amplification protocol–ELISA, mRNA of telomerase subunits, c-myc and bcl-2 by reverse transcript-PCR, terminal restriction fragment (TRF) by Southern blot, cell cycle distribution by flow cytometry and protein expression of hTERT, c-myc and bcl-2 by Western blot were analyzed in SGC-7901 cells before and after transfection. Cloning efficiency assay in soft agar and tumorigenesis in nude mice were also examined and evaluated in the above cells. The results demonstrated that after ahTERT transfection, the proliferation of SGC-7901 cells was significantly inhibited. Further study showed that telomerase activity, telomere length, the mRNA and protein expression of hTERT, bcl-2 and c-myc were decreased in ahTERT-transfected cells. There were, however, no obvious effects on transcription of human telomerase RNA (hTR) and human telomerase associated protein1 (TP1) in both transfected and untransfected cells. Flow cytometric analysis displayed an accumulation of G0/G1 phase and a decreasing proliferation index (PI) in ahTERT-transfected cells. Moreover, no tumorigenicity was found after subcutaneous injection of ahTERT-transfected cells in nude mice, whereas palpable tumors were observed in mice injected with control cells. Our study indicates that exogenous ahTERT can inhibit proliferation and partially reverse malignant phenotypes of SGC-7901 cells via the suppression of telomerase activity, hTERT, c-myc and bcl-2 expression. Antisense technology targeted hTERT strategy might be a potential approach for gastric cancer therapy.

Induction of anti-tumour immunity by dendritic cells transduced with hTERT recombinant adenovirus in mice.

Dendritic cells (DCs) transfected with recombinant, replication‐defective adenovirus (Ad) vectors encoding the human telomerase reverse transcriptase (hTERT) are potent inducers of cytotoxic T lymphocytes (CTLs) and anti‐tumour immunity. However, previous studies have mostly been in vitro. In this study, we sought to determine whether DCs transfected with hTERT (DC/Ad‐hTERT) could elicit a potent anti‐tumour immunogenic response in vivo. We found that murine DCs transfected with recombinant adenovirus encoding the hTERT gene (DC/Ad‐hTERT) induced hTERT‐specific CTLs in vivo effectively, compared with Ad‐LacZ‐transduced DC (DC/Ad‐LacZ) controls. These hTERT‐specific CTLs lysed various tumour cell lines in an hTERT‐specific and MHC‐I molecule‐restricted fashion. We also found that DC/Ad‐hTERT could increase antigen‐specific T‐cell proliferation and augment the number of IFN‐γ secreting T‐cells in mice. These data suggest that the DC/Ad‐hTERT vaccine may induce anti‐tumour immunity against tumour cells expressing hTERT in an MHC‐I molecule‐restricted fashion in vivo through the augmentation of the hTERT‐specific CTL response. The DC/Ad‐hTERT vaccine may thus be used as an efficient DC‐based tumour vaccine in clinical applications. Copyright

Helicobacter pylori infection induces apoptosis in gastric cancer cells through the mitochondrial pathway.

Background and Aims:  To clarify the role of the mitochondrial pathway in apoptosis induced by H. pylori infection in gastric epithelial cells.

Effects of insulin-like growth factors-IR and -IIR antisense gene transfection on the biological behaviors of SMMC-7721 human hepatoma cells

Background and Aims: Insulin‐like growth factors (IGFs) are closely related to hepatocellular carcinoma growth. The study aim was to investigate the effects of IGF‐IR and IGF‐IIR antisense gene transfection on the biological behaviors of SMMC‐7721 human hepatoma cells.

Effect of antisense human telomerase RNA on malignant phenotypes of gastric carcinoma

Aim : The study was designed to explore the effects of antisense human telomerase RNA (ahTR) on the malignant phenotype of gastric carcinoma cell line SGC‐7901, and its potential role in gene therapy for tumors.