Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024623 (gastric cancer)
 36,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human gastric cancer SNU 484 cells express mutant p16, which migrates slower than the wild-type p16. We constructed an expression vector containing human p16 cDNA to evaluate the cytotoxic effects of exogenous p16 expression on SNU 484 cell proliferation and to explore the potential use of p16 in cancer gene therapy. The stable transfectant expressing wild-type p16, showed a 2-fold slower growth rate than mock and non-infected cells through down-regulation of CDK4-dependent kinase activity. When cells were transiently transfected with mock or p16 encoded vector, the mock cells showed larger survival colonies than those of wild-type p16. Furthermore, p16-expressing stable transfectant was readily progressed into cell death by combination with treatment of chemotherapeutic drug in a dose-dependent manner. According to western blot analysis, both decreased expression of pRB and increased expression of E2F-1 may contribute to the susceptibility of cell death. Our data indicate that exogenous wild-type p16 induces delayed cell proliferation and promotes chemo-sensitivity in the gastric cancer cell line, implying the promise of p16 in cancer gene therapy.
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PMID:Exogenous wild-type p16INK4A gene induces delayed cell proliferation and promotes chemosensitivity through decreased pRB and increased E2F-1 expressions. 1279 10

For the early detection of tumor-related aberrant DNA in the serum of patients, we examined promoter hypermethylation of the p16 gene using methylation-specific PCR (MSP) in paired tumor and serum samples of 60 gastric cancer patients. Aberrant p16 methylation was found in 23 of 60 (38%) primary gastric cancers, but in none of the corresponding gastric mucosae. Of these 23 patients, 6 (26%) exhibited the same alteration in their serum DNA. As a control, we screened for aberrant methylation in the serum DNA of 37 patients with gastric cancers whose corresponding tumor DNA had no methylation in the p16 promoter. We also screened for methylation in the serum DNA of 16 non-cancer individuals. No methylation was found in serum DNA of these control groups. Our results suggest that p16 methylation would be a good marker for the detection of tumor DNA in the serum of primary gastric cancer patients.
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PMID:Detection of p16 promoter hypermethylation in serum of gastric cancer patients. 1282 86

Aberrant hypermethylation of promoter CpG islands is an important mechanism for the inactivation of tumor suppressor genes. CpG island hypermethylation occurs in relation to tumorigenesis or aging. Gastric cancer is one of the tumors with a high level of aberrant CpG island methylation. However, the data on the methylation status of normal gastric mucosa has been very limited. The present study attempted to compare the methylation status of nonneoplastic gastric mucosa, using clinicopathological parameters, including age, gender, Helicobacter pylori (H. pylori), acute and chronic inflammation, and intestinal metaplasia. Two hundred sixty-eight nonneoplastic gastric mucosa samples were studied for the methylation status of 11 genes (COX-2, DAP-kinase, E-cadherin, GSTP1, MGMT, hMLH1, p14, p16, THBS1, TIMP3, and RASSF1A), using methylation-specific PCR. CpG island hypermethylation was found in 53.7, 41, 37.7, 23.1, 18.7, 10.9, 10, 4.1, 3.4, 1.7, 0.4% for DAP-kinase, E-cadherin, THBS1, TIMP3, p14, MGMT, p16, COX-2, GSTP1, hMLH1 and RASSF1A, respectively. Five genes (DAP-kinase, E-cadherin, p14, THBS1, and TIMP-3) showed a general progressive increase in the methylation frequency as a function of aging, whereas the other genes (COX-2, GSTP1, MGMT, hMLH1, p16, and RASSF1A) were rarely methylated. Male patients showed higher numbers of methylated genes than females (3.2 vs. 2.1, respectively, P = 0.002). Gastritis samples with marked intestinal metaplasia, showed higher numbers of genes methylated than those without (3.7 vs. 2.6, respectively, P = 0.021). Gastritis samples with marked infiltration of mononuclear cells displayed higher numbers of genes methylated than those with mild or moderate infiltration of mononuclear cells (3.4 vs. 2.5 or 2.5, respectively, P < 0.05). Our results demonstrated that many genes are methylated in the stomach as a function of age, and suggested that male gender, intestinal metaplasia, and chronic inflammation are closely associated with increased methylation in nonneoplastic gastric mucosa samples.
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PMID:Aberrant CpG island hypermethylation of chronic gastritis, in relation to aging, gender, intestinal metaplasia, and chronic inflammation. 1450 61

Hypermethylation of CpG islands is associated with silencing of various tumor suppressor genes. Recent studies on colorectal and gastric cancer have identified a CpG island methylator phenotype (CIMP), which involves the targeting of multiple genes by promoter hypermethylation. For determination of association between DNA methylation pattern or histological type and CIMP status in gastric carcinoma, CpG islands in the promoters of hMLH1 and CDH1 genes, CpG islands overlapping exon 1 of MGMT and p16(INK4a) genes, and a non-CpG island in exon 1 of the RAR-beta gene were studied. The presence of the CIMP was determined by monitoring five methylated in tumor (MINT ) loci in 103 gastric carcinomas. Among the 103 gastric carcinomas, DNA hypermethylation was detected in the following frequencies: 14 (14%) for hMLH1, 26 (25%) for MGMT, 26 (25%) for p16(INK4a), 54 (52%) for CDH1, and 53 (52%) for RAR-beta. Forty-two (41%) of 103 gastric carcinomas were positive for the CIMP. CIMP and hypermethylation of p16(INK4a) gene were found more frequently in intestinal and diffuse-adherent types than in diffuse-scattered type (P = 0.013 and 0.017, respectively). In contrast, hypermethylation of the CDH1 and RAR-beta genes was more common in the diffuse-scattered type than in the other types (P = 0.008 and 0.007, respectively). In intestinal- and diffuse-adherent-type gastric carcinomas, we found significant associations between the presence of the CIMP and hypermethylation of several genes: hMLH1 (P = 0.006), p16(INK4a) (P = 0.018), CDH1 (P = 0.024), and RAR-beta (P = 0.044). Our overall results suggest that in some intestinal- and diffuse-adherent-type gastric carcinomas, DNA hypermethylation affects non-specific gene promoters concordantly, at least in part, whereas in diffuse-scattered-type gastric carcinoma, DNA hypermethylation affects specific genes such as CDH1 and RAR-beta.
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PMID:DNA methylation of multiple genes in gastric carcinoma: association with histological type and CpG island methylator phenotype. 1455 64

A number of tumor suppressor and tumor-related genes exhibit promoter hypermethylation with resulting gene silencing in human cancers. In addition, several gene promoters have also been shown to become hypermethylated in non-neoplastic cells during aging. To assess the physiological consequence and clinical significance of gene promoter methylation in gastric epithelia, our laboratory has studied the methylation status of tumor suppressor and tumor-related genes, including APC, DAP-kinase, DCC, E-cadherin, GSTP1, hMLH1, p16, PTEN, RASSF1A, RUNX3 and TSLC1, in neoplastic and non-neoplastic gastric epithelia. The tumor suppressor and tumor-related genes, except APC, were generally unmethylated in non-neoplastic gastric epithelia obtained from younger individuals. The frequencies of methylation increased with age to varying degrees in various genes, although GSTP1 and PTEN methylation was completely absent in both neoplastic and non-neoplastic gastric epithelia. The methylation frequencies in each gene were found to be comparable in neoplastic and non-neoplastic gastric epithelia, except the methylation of RUNX3 and TSLC1, which was mostly cancer-specific (P<0.01). When methylation frequencies were compared between non-neoplastic gastric epithelia from cancer-bearing and non-cancer-bearing stomachs, hMLH1 and p16 methylation was more frequent in those from cancer-bearing stomachs (P<0.01). Promoter methylation in tumor suppressor and tumor-related genes initially occurs in non-neoplastic gastric epithelia, increases with age, and ultimately silences gene function to constitute a field-defect that may predispose tissues to gastric cancer evolution. In clinical applications RUNX3 and TSLC1 methylation may be utilized as molecular diagnostic markers, and hMLH1 and p16 methylation as predictors of malignancy in the stomach.
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PMID:Promoter methylation status of tumor suppressor and tumor-related genes in neoplastic and non-neoplastic gastric epithelia. 1470 90

Gastric carcinogenesis involves multiple genetic and epigenetic alterations. Epigenetic silencing of tumor-related genes due to CpG island methylation (CIM) has been recently reported in gastric cancer, but the role in precursor lesions is not well understood. We analysed the methylation status of the tumor suppressor gene p16, the DNA mismatch repair gene hMLH1, and four CpG islands (MINT1, MINT2, MINT25, and MINT31) using methylation-specific polymerase chain reaction in 35 polypoid adenomas and 46 flat dysplasias unassociated with carcinoma, 34 early adenocarcinomas (T1N0M0) and associated adenomas/dysplasias, and corresponding adjacent non-neoplastic mucosa. The extent of CIM was defined by the fraction of methylated loci (methylation index), and compared with previously characterized genetic alterations (microsatellite instability (MSI) and APC gene mutation). We found that methylation of p16 was more frequent in adenocarcinoma-associated dysplasias/adenomas (29%) and adenocarcinomas (44%) as compared to flat dysplasias (4%) and adenomas (18%) unassociated with adenocarcinoma (P=0.001). The mean methylation index increased from normal/chronic gastritis (CG) mucosa (0.09) to intestinal metaplasia (IM) (0.16), flat dysplasias (0.40) or polypoid adenomas (0.41) unassociated with carcinoma, dysplasias/adenomas associated with carcinoma (0.44), and adenocarcinomas (0.44). There was no difference in frequencies of high-level CpG island methylation (CIM-H, methylation index > or =0.5) among flat dysplasias (50%) and polypoid adenomas (51%) unassociated with carcinoma, dysplasias/adenomas associated with adenocarcinoma (47%), and adenocarcinoma (47%). CIM-H was present in 15% of IM, but not in normal/CG mucosa. There was a significant correlation between methylation of hMLH1 and high-level of microsatellite instability (MSI-H): methylation of hMLH1 was present in 71% of MSI-H tumors, but only 8% of MSI-low tumors and 13% of microsatellite-stable tumors (P=0.0001). There was no statistical difference between methylation index and APC mutation. Our results indicate that concurrent promoter methylation is an early and frequent event in gastric tumorigenesis, including both MSI-H and microsatellite-stable neoplasms. Methylation of the p16 gene may contribute to the malignant transformation of gastric precursor lesions.
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PMID:Frequent CpG island methylation in precursor lesions and early gastric adenocarcinomas. 1506 7

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has become a fundamental procedure for gastrointestinal and lung cancer staging. However, there is growing evidence that micrometastases are present in lymph nodes, which cannot be detected with standard pathological methods. The aim of this study was to evaluate whether hypermethylation gene promoter analysis was feasible on samples obtained by EUS-FNA from lymph nodes, as well as to establish the usefulness of this strategy for the detection of micrometastases in patients with gastrointestinal and non-small cell lung cancer. Suspicious lymph nodes based on EUS findings from consecutive patients with esophageal, gastric, rectal, and non-small cell lung cancer were sampled by EUS-FNA. Hypermethylation analysis of the MGMT, p16(INK4a), and p14(ARF) gene promoter CpG islands were performed by methylation-specific PCR. Effectiveness of conventional cytology, methylation analysis, and their combination were established with respect to the definitive diagnosis. Twenty-seven patients were included, thus representing a total of 42 lymph nodes (esophageal cancer, n = 11; rectal cancer, n = 7; gastric cancer, n = 3; and lung cancer, n = 21). According to definitive diagnosis, 21 (50%) corresponded to metastatic lymph nodes. Sensitivity, specificity, and overall accuracy of conventional cytology were 76%, 100%, and 88%, respectively, whereas the corresponding values for the methylation analysis were 81%, 67%, and 74%, respectively. Combination of both techniques increased sensitivity (90%) but decreased specificity (67%) with respect to conventional cytology. In conclusion, it is feasible to detect occult neoplastic cells in EUS-FNA samples by hypermethylation gene promoter analysis. Moreover, addition of methylation analysis to conventional cytology may increase its sensitivity at the expenses of a decrease in its specificity.
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PMID:Detection of lymph node micrometastases by gene promoter hypermethylation in samples obtained by endosonography- guided fine-needle aspiration biopsy. 1524 May 35

Epigenetic gene silencing through DNA methylation is one of the important steps in the mechanism underlying tumorigenesis, including in the stomach. Past lifestyle factors of cancer patients, such as intake of vegetables, are very important in affecting gastric carcinogenesis. However, the relationship between DNA methylation and past dietary habits in cancer patients remains largely unknown. The CDX2 homeobox transcription factor plays a key role in intestinal development, but CDX2 is also expressed in most of the intestinal metaplasia and part of the carcinomas of the stomach. We analyzed the methylation status of the CDX2 5' CpG island in gastric cancer cell lines by methylation-specific PCR (MSP), and then CDX2 mRNA was found to be activated after 5-aza-2'-deoxycytidine treatment of the methylation-positive cells. We further examined the methylation status of CDX2 in primary gastric carcinomas by MSP and compared it with the past lifestyle of the patients, including dietary habits. Methylation of CDX2 was found in 20 (34.5%) of the 58 male patients and one (6.7%) of the 15 female patients. Since the methylation frequency was low in the female patients, the analysis was performed only on the male cases. CDX2 methylation was correlated with the decreased intake of green tea and cruciferous vegetables, and also with full or overeating habits. These findings are consistent with epidemiological observations on gastric cancer. We also analyzed the methylation status of p16/INK4a and hMLH1, but their frequencies were not associated with dietary factors or other lifestyle factors. Thus, diet could be an important factor determining the methylation status of genes such as CDX2 and the resultant aberrant expression of genes involved in carcinogenesis.
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PMID:Relationship between CDX2 gene methylation and dietary factors in gastric cancer patients. 1549 92

The induction of apoptosis and antiproliferation effect of cytokine-induced killer cells (CIK cells) on MGC- 803 cells and its mechanisms were studied by using a tetrazolium dye-based (MTT) assay. Morphological changes were observed by using inverted microscope, haematoxylin/eosin (HE) staining, scanning electron microscope, and transmission electron microscope. The TdT-mediated dUTP nick and labeling (TUNEL) method was used to detect the apoptosis-induced by CIK cells. The expression rate of p53, p16, C-myc, Bcl-2, and Bax proteins were studied by using immunohistochemical staining. There were significant differences according to varied effector-target ratios at the same working time (p < 0.01) and the same effector-target ratios at different working times (p < 0.01). Inverted microscope and HE staining observation showed that CIK cells were closer to the target cells and formed a typical "rose" shape. The scanning electron microscope showed that most target cells had undergone apoptosis and many "apoptotic bodies," and that transmission electron microscopy showed condensed chromatin, disintegration of the nucleolus, vacuoles in the cytoplasm, and apoptotic bodies appearing in most target cells. TUNEL analysis showed that apoptotic cells contract and turn navy blue in nuclei or perinuclei in the experimental group. The apoptotic rate was upmodulated between 5 and 14 hours and downregulated between 14 and 24 hours in the "CIK" experimental group. The expression of p53, p16, C-myc, and Bcl-2 were significantly downregulated (p < 0.01), and the expression of Bax was upregulated over the time of coculture in the "CIK" experimental group, compared to the control group. Our studies suggested that CIK cells induce apoptosis and have an antiproliferative effect on human MGC-803 gastric cancer cells. The CIK cells kill MGC-803 gastric cancer cells by inducing apoptosis in the early stage and by inducing necrosis in the late stage through the downregulating expression of p53, C-myc, and Bcl-2 and the upregulating expression of Bax.
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PMID:Studies on inducing apoptosis effects and mechanism of CIK cells for MGC-803 gastric cancer cell lines. 1586 51

While there is no reliable serum biomarker for the diagnosis and monitoring of patients with gastric cancer, we tested the potential diagnostic and prognostic values of detecting methylation changes in the serum of gastric cancer patients. DNA was extracted from the pretherapeutic serum of 60 patients with confirmed gastric adenocarcinoma and 22 age-matched noncancer controls. Promoter hypermethylation in 10 tumour-related genes (APC, E-cadherin, GSTP1, hMLH1, MGMT, p15, p16, SOCS1, TIMP3 and TGF-beta RII) was determined by quantitative methylation-specific PCR (MethyLight). Preferential methylation in the serum DNA of gastric cancer patients was noted in APC (17%), E-cadherin (13%), hMLH1 (41%) and TIMP3 (17%) genes. Moreover, patients with stages III/IV diseases tended to have higher concentrations of methylated APC (P = 0.08), TIMP3 (P = 0.005) and hMLH1 (P = 0.03) in the serum. In all, 33 cancers (55%) had methylation detected in the serum in at least one of these four markers, while three normal subjects had methylation detected in the serum (specificity 86%). The combined use of APC and E-cadherin methylation markers identified a subgroup of cancer patients with worse prognosis (median survival 3.3 vs 16.1 months, P = 0.006). These results suggest that the detection of DNA methylation in the serum may carry both diagnostic and therapeutic values in gastric cancer patients.
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PMID:Potential diagnostic and prognostic values of detecting promoter hypermethylation in the serum of patients with gastric cancer. 1594 35


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