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)

This study was designed to clarify the role of endogenous Bcl-xL expression in modulating apoptosis of malignant cells. Administration of bcl-x-antisense oligonucleotides decreased Bcl-xL protein levels in the MKN-45 human gastric cancer cell line. The decrease in Bcl-xL protein content resulted in increased cell death induced by serum deprivation or Fas-antibody administration. Flow cytometric analysis revealed that the increased apoptotic cell death was more prominent in bcl-x-antisense-treated cells as compared to control cells, bcl-x-sense-treated cells, or bcl-x-nonsense-treated cells. To inhibit the effect of intrinsic Bcl-xL protein, we overexpressed Bak, which binds Bcl-xL and inhibits the anti-apoptotic effect of Bcl-xL, by transfection into MKN-45 cells. Bak-overexpressing cells showed increased apoptotic cell death induced by Fas-antibody when compared to parent cells and MKN-neo-transfected cells. Bak-overexpressing cells also showed greater sensitization to 5-fluorouracil and cisplatin than parent cells and MKN-neo-transfected cells. In conclusion, we demonstrated that administration of bcl-x-antisense oligonucleotides or overexpression of Bak protein induces sensitization to apoptosis in MKN-45 gastric cancer cells, suggesting that endogenous Bcl-xL expression in cancer cells is an important modulator of apoptosis.
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PMID:Modulation of apoptosis by endogenous Bcl-xL expression in MKN-45 human gastric cancer cells. 984 Sep 21

Chemotherapeutic drugs cause DNA damage and kill cancer cells mainly by apoptosis. p53 mediates apoptosis after DNA damage. To explore the pathway of p53-dependent cell death, we investigated if p53-dependent apoptosis after DNA damage is mediated by the CD95 (APO-1/Fas) receptor/ligand system. We investigated hepatoma, gastric cancer, colon cancer, and breast cancer cell lines upon treatment with different anticancer agents known to act via p53 accumulation. Cisplatin, mitomycin, methotrexate, mitoxantrone, doxorubicin, and bleomycin at concentrations present in the sera of patients during therapy led to an upregulation of both CD95 receptor and CD95 ligand. Induction of the CD95 ligand occurred in p53 wild-type (wt), p53 mutant (mt), and p53 deficient (p53(-/-)) cell lines and at wt and mt conformation of temperature-sensitive p53 mutants. In contrast, upregulation of the CD95 receptor was observed only in cells with wt p53, not in cells with mt or without any p53. Restitution of inducible wt p53 function restored the ability of p53(-/-) Hep3B cells to upregulate the CD95 receptor in response to anticancer drugs. This rendered the cells sensitive to CD95-mediated apoptosis. In an attempt to understand how CD95 expression is regulated by p53, we identified a p53-responsive element within the first intron of the CD95 gene, as well as three putative elements within the promoter. The intronic element conferred transcriptional activation by p53 and cooperated with p53-responsive elements in the promoter of the CD95 gene. wt p53 bound to and transactivated the CD95 gene, whereas mt p53 failed to induce apoptosis via activation of the CD95 gene. These observations provide a mechanistic explanation for the ability of p53 to contribute to tumor progression and to resistance of cancer cells to chemotherapy.
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PMID:p53 activates the CD95 (APO-1/Fas) gene in response to DNA damage by anticancer drugs. 984 17

Pierisin, a protein purified from pupae of the cabbage butterfly, Pieris rapae, exhibits cytotoxic effects against the human gastric cancer TMK-1 cell line, inducing apoptosis. The present study was performed to determine whether pierisin might exert a similar influence on nine other human cancer cell lines and human umbilical vein endothelial cells (HUVECs). Pierisin showed cytotoxic effects in all the human cells tested, with IC50 values ranging from 0.043 ng/ml to 150 ng/ml. Among the target cells, the cervical carcinoma cell line, HeLa, was the most sensitive to pierisin, showing a 1000-fold less IC50 value than that of HUVECs. While pierisin clearly induced apoptotic cell death in most cancer cell lines and HUVECs, the pathway appeared to be probably different from that involving anti-Fas, TNF-alpha and p53. Pierisin may thus be a promising new candidate for cancer therapy.
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PMID:Cytotoxic activity of pierisin, from the cabbage butterfly, Pieris rapae, in various human cancer cell lines. 1037 96

Intestinal trefoil factor (ITF) is an essential regulator of colonic epithelial restitution, the rapid migration of colonocytes over mucosal wounds. High levels of ITF are frequently present in colorectal cancers and derived cell lines. Mucosal restitution requires the detachment of epithelium from substrate, which would be expected to induce apoptosis. However, mice deficient in ITF showed an increase in colonocyte apoptosis unaccompanied by changes in expression of receptor-related (TNFR/Fas) or stress-related (Bcl-family) cell death regulators. An ITF-expressing colonic (HT-ITF1) cell line was resistant to apoptosis induced by serum starvation and ceramide. Exogenous ITF also protected another human colonic carcinoma-derived cell line (HCT116) and a nontransformed rat intestinal epithelial cell line (IEC-6) from apoptosis. This effect was abrogated by wortmannin and tyrphostin A25, indicating the potential involvement of phosphatidylinositol 3-kinase and epidermal growth factor (EGF) receptor activation. Expression of phosphorylated Akt, which lies downstream of phosphatidylinositol 3-kinase activation, was elevated in this HT-29-ITF line. p53-dependent cell death in the AGS human gastric cancer cell line after etoposide was similarly inhibited by transient expression of ITF but not a C-terminal truncation mutant of ITF, and it required functional phosphatidylinositol 3-kinase and EGF receptor. These findings support a central role for ITF in the maintenance of intestinal mucosal continuity, and conversely demonstrate the potential for ITF expression to confer resistance of colorectal tumors to therapy.
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PMID:Intestinal trefoil factor confers colonic epithelial resistance to apoptosis. 1063 60

It is now believed that genes regulating apoptosis are also important variables in cancer development. Fas, a transmembrane protein of the tumour necrosis factor receptor family, is a key molecule for cell death signalling. The mutation of the primary structure of the Fas gene might also be one of the possible mechanisms that disrupt Fas-mediated apoptosis in tumour cells. The purpose of this study was to determine whether somatic mutation of the Fas gene could be involved in the tumourigenesis of gastric cancer. Polymerase chain reaction (PCR)-based loss of heterozygosity (LOH) analysis with two intragenic polymorphic markers, and mutation analysis for the entire coding regions of the Fas gene were performed in 43 cases of gastric cancer, using PCR-single-strand conformational polymorphism sequencing. Five (11.6%) missense mutations were detected, only in the death domain of the Fas gene. Although these mutations were observed only in intestinal-type gastric cancers, there was no statistically significant difference in the frequency of Fas mutation between intestinal- and diffuse-type gastric cancer (p=0.068). Nine LOH out of 22 informative cases were also detected with one or both markers (41%). Three of them demonstrated a somatic mutation in the remaining allele, indicating the inactivation of both alleles. These results suggest that genetic alterations of the Fas gene may not only be limited to gastric cancer cell protection through Fas resistance, but may also play an important role in tumour promotion and/or progression in a subset of gastric cancer.
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PMID:Somatic mutations in the death domain of the Fas (Apo-1/CD95) gene in gastric cancer. 1118 Jan 61

Fas ligand (FasL), which induces apoptosis against Fas-expressing cells, has been found to be expressed on various cell types including cancer cells. Membrane-bound FasL is cleaved to release soluble FasL (sFasL). Although serum or plasma sFasL concentration has been reported to increase in various diseases, sFasL concentration in healthy normal persons has not been fully studied. There have been few reports on sFasL concentrations in patients with carcinomas. We measured plasma sFasL concentrations using an enzyme-linked immunosorbent assay in 155 healthy volunteers (70 males and 85 females with an average age of 41.5+/-15.4) and 112 patients with gastric carcinoma (76 males and 36 females with an average age of 62.3+/-11.5). A significant negative correlation existed between age and plasma sFasL concentration in healthy volunteers. sFasL concentrations in males were significantly lower than those in females. Plasma sFasL levels were significantly higher in patients with gastric carcinoma than in healthy volunteers when male subjects aged 50 or older were analyzed, although no significant difference existed between the groups in the age bracket of 35 to 49. Male patients aged 50 or older with stage 1B or 2 tumors showed significantly higher plasma sFasL concentrations than those with stage 1A tumors or those with stage 3 or 4 tumors. In conclusion, age- and gender-matched controls should be used when plasma sFasL concentration is investigated. The origin and physiological or clinical significance of plasma sFasL in healthy volunteers and gastric cancer patients remain to be clarified.
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PMID:Plasma soluble Fas ligand concentration: decrease in elderly men and increase in patients with gastric carcinoma. 1118 46

AIM:To compare the expression level of Fas gene and Bcl-2 gene in gastric cancer cells SGC7901 and gastric cancer MDR (multidrug resistant) cells SGC7901/VCR,to transduce Fas cDNA and Bcl-2 antisense nucleic acid into SGC7901/VCR cells respectively, and to observe the expression of two genes in transfectants and non-transfectants as well as their drug sensitivity.METHODS:Eukaryotic expression vector pBK-Fas cDNA and pDOR-anti Bcl-2 were constructed and transfected into SGC7901/VCR cells by lipofectamine,respectively.Northern blot and Western blot were used to detect the expression of mRNA and protein in SGC7901/VCR and SGC7901 cells and transfectants, and drug sensitivity of transfectants for VCR, CDDP and 5-FU was analyzed with MTT assay.RESULTS:After gene transfection, 80 for Fas and 120 for antisense Bcl-2 drug-resistant clones were selected from 2 X10(5) cells, transfection rate being 0.04% and 0.06%. Two clones of SGC7901 Fas/VCR cells and SGC7901 anti Bcl-2/VCR cells were randomly selected for further incubation. Hybridization results showed that the expression level of Fas mRNA and protein in SGC7901/VCR cells was much lower,but that of Bcl-2 mRNA and protein was higher than that in SGC7901 cells. The expression of Fas mRNA and protein in SGC7901 Fas/VCR cells was higher,and of Bcl-2 mRNA and protein was lower in SGC7901 anti Bcl-2/VCR cells than that in non-transfectants. MTT assay showed that transfectants were more sensitive to VCR, CDDP, 5-FU than non-transfectants. CONCLUSION:Bcl-2 gene displayed high expression while Fas gene had low expression in drug resistant gastric cancer cells. Expression of Bcl-2 protein was effectively blocked in SGC7901 anti Bcl-2/VCR cells by gene transfection. In contrast, the expression of Fas mRNA and protein in SGC7901 Fas/VCR cells increased. Fas gene and Bcl-2 antisense nucleic acid transfection sensitized drug resistant gastric cancer cells to chemotherapeutic drugs. These results suggest cell apoptosis plays an important role in the mechanism of MDR, and enhancing apoptosis might reverse MDR.
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PMID:Transduction of Fas gene or Bcl-2 antisense RNA sensitizes cultured drug resistant gastric cancer cells to chemotherapeutic drugs. 1181 36

The aims of this study were to determine whether human gastric adenocarcinomas express FasL or Fas, whether FasL expression is associated with increased apoptotic induction, especially, tumor-infiltrating lymphocyte (TIL) and whether apoptotic induction is associated with the tumor stage and histologic type. Early gastric carcinoma (EGC) (n=38) and advanced gastric carcinoma (AGC) (n=61) cases were analyzed in patients who received gastric resection from 1997 to 1998. There were 38 diffuse type and 61 intestinal type cases. Immunohistochemical staining for Fas, FasL and CD45, TACS trade mark in situ apoptosis detection kit, and double staining with the observation under a confocal scanning laser microscope were employed. FasL was localized to neoplastic cells in 23 cases (61%) of EGC group and 40 cases (66%) of AGC group. The extent of FasL expression was variable, with both FasL-positive and -negative neoplastic regions occurring within tumors. TILs were detected by CD45, and apoptosis of TILs as detected by co-expression of CD45 and TACS on serial histologic sections. TILs adjacent to FasL expressing tumor regions were decreased in number and TILs adjacent to FasL-negative tumor regions were increased in number; apoptotic induction of TIL showed the opposite pattern (p<0.05). Fas was expressed homogeneously throughout the tumor masses independent of the tumor stage. Fas expression in 39 cases (64%) was intestinal type and in 26 cases (68%), diffuse type. Labeling indices for tumoral apoptosis in EGC and AGC were 6.72% and 7.13%, respectively. Co-expression of FasL and Fas, which occurrs over large areas of the tumors, did not result in an enhanced rate of tumor cell apoptosis. In addition, tumor stage and other prognostic factors were not associated with Fas and FasL expressions, number of TIL and apoptotic induction. A statistically significant reduction of TILs concomitant with significantly increased TIL apoptosis adjacent to FasL-expressing regions of gastric adenocarcinomas were demonstrated. This finding suggests Fas-mediated apoptotic depletion of TIL in response to FasL expression in stomach cancers, and provides evidence to support the Fas counterattack theory as a mechanism of immune escape in gastric cancer. Furthermore, gastric carcinoma cells of the intestinal and the diffuse type did not differ in their expression of the Fas-apoptotic system.
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PMID:Fas-related apoptosis in gastric adenocarcinoma. 1246 45

To determine a cellular factor supporting the survival of gastric cancer cells, a comparative study was performed using two human adenocarcinoma cell lines, SNU-16 and SNU-620. The latter cells were significantly less susceptible to various lethal stimuli including anti-Fas, H(2)O(2), etoposide, and serum withdrawal than the former. These stimuli were found to kill the SNU-16 cells by activating stress-activated protein kinase (SAPK)/c-Jun NH(2)-terminal kinase (JNK), whereas SAPK/JNK activation was not efficiently induced in the SNU-620 cells. Western blot analysis revealed that Bcl-w, but not the other tested members of the Bcl-2 family, was expressed in the SNU-620 cells to levels higher than that observed in SNU-16 cells. An elevation of the Bcl-w levels in the SNU-16 cells by its stable transfection attenuated both the SAPK/JNK activation and the cell death induced by all of the tested stimuli. These results suggest that the susceptibility of gastric cancer cells to death stimuli is determined, at least in part, by the levels of Bcl-w that suppress the cell death by blocking SAPK/JNK activation. To examine whether Bcl-w was expressed in patients, tumor specimens were obtained from 50 consecutive advanced gastric adenocarcinoma cases. An immunohistochemical analysis showed that Bcl-w was expressed in cancer cells but not in the neighboring normal mucosa of the 23 cases (46%). Interestingly, Bcl-w expression was associated significantly with certain histopathological characteristics of the cancer, notably with the infiltrative morphotypes (P < 0.001). Therefore, Bcl-w appears to be important for gastric cancer cell survival, particularly in infiltrative tumors.
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PMID:Bcl-w is expressed in a majority of infiltrative gastric adenocarcinomas and suppresses the cancer cell death by blocking stress-activated protein kinase/c-Jun NH2-terminal kinase activation. 1261 27

Despite the cell surface expression of Fas (Apo-1/CD95), many types of tumor cells, including stomach cancer cells, are resistant to Fas-mediated apoptosis, indicating the presence of inactivating mechanisms of Fas signaling. Expression of FLICE-like inhibitory protein (FLIP), one of the inhibitory proteins of Fas-mediated apoptosis, has been reported in several cancer types, but not in stomach cancer. In the present study, we analyzed the expression of Fas and FLIP in 60 advanced gastric adenocarcinomas by immunohistochemistry using a tissue microarray approach. Immunopositivity (defined as >/=30% of the neoplastic cells) was observed for Fas in 58 (97%) and FLIP in 54 (90%) of the 60 cancers. All of the tumors with FLIP immunostaining also showed Fas immunostaining. Loss of cell surface Fas immunostaining, another mechanism of Fas resistance, was observed in 45 tumors (75%). By contrast, normal gastric mucosal cells showed no or weak expression of both Fas and FLIP. Taken together, these results indicate that increased expression of FLIP is a frequent event in stomach carcinomas, and suggest that for evading apoptosis stomach carcinoma cells in vivo may need FLIP expression, which might contribute to tumor development.
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PMID:Increased expression of FLIP, an inhibitor of Fas-mediated apoptosis, in stomach cancer. 1271 87


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