Effect of human noxa on irinotecan-induced apoptosis in human gastric carcinoma cell lines

BACKGROUND/AIMS: A protein BH3-only member bcl-2 family, Noxa is a proapoptotic mediator for p53-induced apoptosis. We analyzed the effect of Noxa on p53-induced apoptotic gastric carcinoma cell lines. METHODOLOGY: The expressions of human Noxa (hNoxa) mRNA on human gastric carcinoma cell lines were assessed with RT-PCR. Further, hNoxa antisense and sense S-oligodeoxynucleotide (ODN) were used to analyze the effect of hNoxa on p53-induced apoptotic gastric carcinoma cell lines. RESULTS: Various levels of hNoxa mRNA expression were detected in all gastric cell lines. MKN45 that has wild-type p53 showed severe inhibition by irinotecan compared with MKN28, which has mutated p53. Cell growth under hNoxa antisense S-ODN treatment did not differ from that under sense S-ODN treatment in MKN28. On the other hand, the suppression of cell growth in MKN45 decreased with hNoxa antisense S-ODN treatment as compared to hNoxa sense S-ODN treatment. MKN45 cells exhibited DNA fragmentation clearly after 24 hr of 3 mM hNoxa sense S-ODN treatment. The DNA fragmentation in MKN45 was inhibited by hNoxa antisense S-ODN treatment. CONCLUSIONS: It seems that hNoxa plays an important role in induction of apoptosis on p53 wild type gastric carcinoma cell lines.     

E-cadherin distribution in interleukin 6-induced cell-cell separation of ductal breast carcinoma cells.

E-cadherin is expressed in both the ZR-75-1-Tx and the ZR-75-1-Ro sublines of ductal breast carcinoma cells and is concentrated at cell-cell borders as shown by immunocytochemical examination. Free cell borders generally show no or little staining. The localized decrease in E-cadherin expression observed after interleukin 6 (IL-6) treatment of either subline correlates with the increase in free cell borders as IL-6 causes cell-cell separation. As we previously reported, many IL-6-treated ZR-75-1-Tx cells round up and detach from the substratum while ZR-75-1-Ro cells remain adherent and display prominent processes. The results are consistent with the view that E-cadherin expression is not responsible for the marked difference in the IL-6-induced phenotypes in these cell lines, although the localized decrease may play a role in cell-cell separation. ZR-75-1-Tx cells are deficient in desmosomes and show a wider intercellular space than ZR-75-1-Ro cells. Alternative mechanisms involving different aspects of the interlinked cytoskeletal and cell adhesion structures are considered to account for the IL-6-induced antimorphogenetic effect.     

Type I collagen and divalent cation shifts disrupt cell-cell adhesion, increase migration, and decrease PTHrP, IL-6, and IL-8 expression in pancreatic cancer cells

Background: We have shown in FG pancreatic cancer cells that α₂β₁ integrin-mediated type I collagen adhesion decreases parathyroid hormone-related protein (PTHrP), inerleukin-6 (IL-6), and interleukin-8 (IL-8) expression, decreases the localization of E-cadherin and β-catenin in cell-cell contacts, increases cell migration, and increases glycogen synthase kinase 3 (GSK3) and protein kinase B (PKB/Akt) phosphorylation states relative to α₅β₁ integrin-mediated fibronectin (Fn) adhesion. Aim of the Study: To extend our observations in FG cells to other pancreatic cancer cell lines, and to determine whether E-cadherin-mediated cell-cell adhesion and its downstream effectors were functionally involved in the ECM-mediated regulation of PTHrP, IL-6, and IL-8. Methods: We used standard biochemical techniques to determine ECM-specific differences in E-cadherin and β-catenin localization, GSK3 and PKB/Akt phosphorylation, haptokinetic cell migration, and cytokine expression in pancreatic cancer cells. We also conducted functional studies using pharmacological inhibitors for GSK3 and PKB/Akt, as well as elevated Mg²⁺/Ca²⁺ ratios similar to pancreatic juice, and examined their effects on cytokine expression. Results: Differences in E-cadherin and β-catenin localization along with GSK3 and PKB/Akt phosphorylation occur in multiple pancreatic cancer cell lines, resulting in differences in ECM-mediated haptokinesis and cytokine expression that are generally consistent with previous observations in FG cells. Our functional studies also suggest that E-cadherin-mediated cell-cell adhesion and downstream effectors are involved in PTHrP, IL-6, and IL-8 expression. Conclusions: These data indicate that α₂β₁ integrin-mediated type I collagen adhesion disrupts cell-cell adhesion architecture, resulting in increased migration and decreased PTHrP, IL-6, and IL-8 expression in pancreatic cancer cells.     

Effect and mechanism of the Twist gene on invasion and metastasis of gastric carcinoma cells

AIM： To study the effect of the transfected Twist gene on invasion and metastasis of gastric carcinoma cells and the possible mechanisms involved. METHODS： Human gastric carcinoma MKN28 cells were stably transfected with Twist sense plasmid, and MKN45 cells were stably transfected with Twist antisense plasmid using the lipofectamine transfection technique. RT-PCR, Western blotting, EMSA, gelatin zymography assay, and in vitro invasion and migration assays were performed. Nude mice metastasis models were established by the abdominal cavity transfer method. RESULTS： Cell models （TwistS-MKN28） that steadily expressed high Twist protein were obtained. Compared with MKN28 and pcDNA3-MKN28 cells, adherence, migration and invasion ability of TwistS -MKN28 cells were clearly raised. The number of cancer nodules was increased significantly in the abdominal cavity and liver of nude mice inoculated with TwistS-MKN28 cells. Overexpression of Twist in MKN28 cells increased Tcf-4/ Lef DNA binding activity, and promoted expression of Tcf-4’s downstream target genes cyclin D1 and MMP-2. However, suppression of Twist （TwistAS-MKN45） inhibited MKN45 cell invasion and the expression of cyclin D1 was reduced. The activity of MMP-2 was also decreased. CONCLUSION： These results indicate that Twist promotes gastric cancer cell migration, invasion and metastasis, and Twist may play an important role in Wnt/ Tcf-4 signaling.     

Mutated E-cadherin: genomic and functional characterization in thyroid cells from the KAT family.

Members of a family of thyroid cell lines (KAT) were analyzed because they expressed a higher molecular weight (135 kd) form of E-cadherin at their surface. We found that this aberrant E-cadherin is the result of a point mutation in the exon 9 donor splice site causing a skipping of exon 9 with consequent deletion of the corresponding aminoacids on E-cadherin protein. As a spin-off, we report that the various members of the KAT family share this mutation as well as the genetic background. Furthermore we found that this mutated protein leads to disturbed cell-cell adhesion although E-cadherin is still able to mediate the formation of the cadherin/ catenin complex. We also demonstrate the presence of another cell-cell adhesion complex, formed by Pcadherin and the catenins. The latter is also not able to mediate cell-cell adhesion. Although these cells lack cell-cell adhesion they are not invasive without exogenous stimulus.     

The role of the E-cadherin/catenin complex in gastrointestinal cancer

Cancer is a genetic disease. The unstable genome of cancer cells causes tumour progression through multiple alterations in suppressor and promoter genes, leading to loss of homeostatic and gain of oncogenic functions. Invasion is the critical step in the acquisition of malignancy. It implicates a continuous molecular conversation of the cancer cells with other cells and with the extracellular matrix in which adhesion molecules are crucial. One of these, E-cadherin, is discussed in the present review. E-cadherin is a transmembrane glycoprotein that forms a complex with cytoplasmic proteins, termed catenins because they link E-cadherin to the actin cytoskeleton. E-cadherin/catenin-mediated intercellular adhesion and communication is mainly homophylic homotypic. There is compelling evidence from experiments in vitro as well as in vivo to accept that the E-cadherin/catenin complex acts as an invasion suppressor. The mechanism of this action is not only through cell-cell adhesion but also through transduction of signals to the cell's motility system. In the replication error positive human colon cancer cell line HCT-8, the alpha E-catenin gene CTNNA1 is an invasion suppressor gene. Here, the transition from the non-invasive to the invasive state was prevented by introduction into the unstable non-invasive cells of either an extra CTNNA1 or a wild type hMSH6 mismatch repair gene. beta-catenin also participates at a complex which comprises the adenomatous polyposis cancer protein APC. In colorectal cancer, mutation of either APC or beta-catenin is oncogenic. Downregulation of the E-cadherin/catenin complex may occur in several ways amongst which are gene mutations, methylation of 5'CpG dinucleotides within the promotor region of E-cadherin, tyrosine phosphorylation of beta-catenin, cell surface expression of proteoglycans sterically hindering E-cadherin and proteolytic release of fragments from the extracellular part of E-cadherin. Upregulation of the E-cadherin/catenin complex has been realized with a series of agents, some of which can be used therapeutically. In most human gastrointestinal cancers the E-cadherin/catenin or related complexes are disturbed and this underscores their pivotal role in the progression of these tumours. Mutations of the E-cadherin gene, including germline mutations, occur in diffuse gastric carcinoma, CpG methylation around the promotor region of E-cadherin in hepatocellular carcinomas and mutations of the APC tumour suppressor gene or in the beta-catenin oncogene in most colorectal cancers. The literature agrees about the disturbance of immunohistochemical patterns of E-cadherin and catenin expression in gastrointestinal cancers. Conflicting opinions do, however, exist about the prognostic value of such immunohistochemical aberrations. We doubt that immunohistochemistry of E-cadherin or catenins add prognostic value to the already used histological grading systems. In our opinion the major benefit from understanding of the E-cadherin/catenin-mediated pathways of invasion will be the development of new anti-invasive treatment strategies.     

MUC2反义脱氧寡核苷酸对胃癌细胞体外黏附侵袭活性的影响

目的 探讨黏蛋白MUC2反义脱氧寡核苷酸（ASODN）对人胃癌细胞株SGC7901黏附侵袭活性的影响。方法 采用人工合成的MUC2 ASODN经阳离子脂质体包裹后转染入SGC7901细胞中,采用黏附试验、Boyden小室体外侵袭试验观察比较转染前后癌细胞黏附率,穿膜细胞相对百分率及组织蛋白酶D、钙黏蛋白表达的变化。结果 转染SGC7901细胞48h后,癌细胞黏附率在30、60、90、120min各时间段逐渐升高,但低于空白对照组（P均〈0．01）;转染后癌细胞穿膜细胞相对百分率明显下降;转染后SGC7901细胞的E-钙黏蛋白表达明显增高,组织蛋白酶D水平明显降低。结论 人工合成的MUC2 ASODN能有效抑制胃癌细胞株SGC7901黏附侵袭能力。     

ADAM10 mediates E-cadherin shedding and regulates epithelial cell-cell adhesion, migration, and beta-catenin translocation

E-cadherin controls a wide array of cellular behaviors, including cell-cell adhesion, differentiation, and tissue development. We show here that E-cadherin is cleaved specifically by ADAM (a disintegrin and metalloprotease) 10 in its ectodomain. Analysis of ADAM10-deficient fibroblasts, inhibitor studies, and RNA interference-mediated down-regulation of ADAM10 demonstrated that ADAM10 is responsible not only for the constitutive shedding but also for the regulated shedding of this adhesion molecule in fibroblasts and keratinocytes. ADAM10-mediated E-cadherin shedding affects epithelial cell-cell adhesion as well as cell migration. Furthermore, the shedding of E-cadherin by ADAM10 modulates the beta-catenin subcellular localization and downstream signaling. ADAM10 overexpression in epithelial cells increased the expression of the beta-catenin downstream gene cyclin D1 dose-dependently and enhanced cell proliferation. In ADAM10-deficient mouse embryos, the C-terminal E-cadherin fragment is not generated, and the full-length protein accumulates, highlighting the in vivo relevance for ADAM10 in E-cadherin shedding. Our data strongly suggest that this protease constitutes a major regulatory element for the multiple functions of E-cadherin under physiological as well as pathological conditions.     

Relevance of MET activation and genetic alterations of KRAS and E-cadherin for cetuximab sensitivity of gastric cancer cell lines

Purpose

The therapeutic activity of the epidermal growth factor receptor (EGFR)-directed monoclonal antibody cetuximab in gastric cancer is currently being investigated. Reliable biomarkers for the identification of patients who are likely to benefit from the treatment are not available. The aim of the study was to examine the drug sensitivity of five gastric cancer cell lines towards cetuximab as a single agent and to establish predictive markers for chemosensitivity in this cell culture model. The effect of a combination of cetuximab with chemotherapy was compared between a sensitive and a nonsensitive cell line.

Methods

EGFR expression, activation and localisation, the presence and subcellular localisation of the cell adhesion molecule E-cadherin as well as MET activation were examined by Western blot analysis, flow cytometry and immunofluorescence staining. Cells were treated with varying concentrations of cetuximab and cisplatin and 5-fluorouracil in tumour-relevant concentrations. The biological endpoint was cell viability, which was measured by XTT cell proliferation assay. Response to treatment was evaluated using statistical methods.

Results

We assessed the activity of cetuximab in five gastric cancer cell lines (AGS, KATOIII, MKN1, MKN28 and MKN45). The viability of two cell lines, MKN1 and MKN28, was significantly reduced by cetuximab treatment. High EGFR expression and low levels of receptor activation were associated with cetuximab responsiveness. MET activation as well as mutations of KRAS and CDH1 (gene encoding E-cadherin) was associated with cetuximab resistance.

Conclusion

These data indicate that our examinations may be clinically relevant, and the candidate markers should therefore be tested in clinical studies.     

Acid exposure potentiates intercellular adhesion molecule-1 and e-cadherin expression on A549 alveolar lining epithelial cells

Recruitment of neutrophils into the alveoli plays a major role in the pathogenesis of acid-induced pneumonitis. Preliminary data suggest that alteration in the expression of cellular adhesion molecules on the airway epithelial cells may play an important role in the recruitment of neutrophils following acid-induced lung injury. The aim of this study was to evaluate the change in the surface expression of intercellular adhesion molecule-1 (ICAM-1), E-cadherin, and vascular cell adhesion molecule -1 (VCAM-1) on acid-exposed A549 alveolar lining epithelial cells by flow cytometry and confocal laser microscopy. Acid exposure changed cell morphology, increased cell adhesion after trypsin-EDTA treatment, and up-regulated the expression of ICAM-1 and E-cadherin but not of VCAM-1. The up-regulation of ICAM-1 expression will induce the dysfunction of epithelial cells with or without accumulation of neutrophils in air spaces. Because the distribution of E-cadherin in acid-exposed A549 cells was at the sites where the cells attached to culture dish but not at the intercellular junctions between adjoining cells, up-regulated expression of E-cadherin will rather result in alterations of epithelial morphology and function of epithelial barrier. In addition, pentoxifylline suppressed the up-regulation of ICAM-1 and E-cadherin expression and may therefore attenuated the airway inflammation in acid-induced pneumonitis.     

Endothelial adhesion of synchronized gastric tumor cells changes during cell cycle transit and correlates with the expression level of CD44 splice variants

AIM: To study adhesion capacity and CD44 expression of human gastric adenocarcinoma MKN45 cells at different stages of a first cell cycle.METHODS: MKN45 cells were synchronized by aphidicolin and assayed for adhesion to an endothelial cell (HUVEC)monolayer. Surface expression of CD44 and CD44 splice variants on MKN45 cells was evaluated by flow cytometry.Functional relevance of CD44 adhesion receptors was investigated by blocking studies using anti CD44 monoclonal antibodies or by hyaluronan digestion.RESULTS: Adhesion of MKN45 to HUVEC was increased during G2/M transit, after which adhesion returned to baseline levels with cell cycle completion. In parallel, CD44splice variants CD44v4, CD44v5, and CD44v7 were all upregulated on MKN45 during cell cycle progression with a maximum effect in G2/M. The function of CD44 surface receptors was assessed with specific receptor blocking monodonal antibodies or removal of hyaluronan by digestion with hyaluronidase. Both strategies inhibited tumor cell adhesion to HUVEC by nearly 50%, which indicates that MKN45-HUVEC-interaction is CD44 dependent.CONCLUSION: CD44 expression level is linked to the cell cycle in gastrointestinal tumor cells, which in turn leads to cell cyde dependent alterations of their adhesion behaviour to endothelium.     

Inhibition of KL-6/MUC1 glycosylation limits aggressive progression of pancreatic cancer

AIM:To evaluate the significance of KL-6/MUC1(a type of MUC1)glycosylation in pancreatic cancer progression.METHODS:KL-6/MUC1 expression was detected by immunohistochemistry in 48 patients with pancreatic duct cell carcinoma.The N-/O-glycosylation inhibitors(tunicamycin and benzyl-N-acetyl-α-galactosaminide)were then used to interfere with KL-6/MUC1 glycosylation in two pancreatic carcinoma cell lines,and the effects on KL-6/MUC1 expression,and cell adhesion and invasion were determined.In addition,protein expression of epithelial-mesenchymal transition markers,E-cadherin and vimentin,were evaluated in cells after treatment with glycosylation inhibitors.RESULTS:Overexpression of KL-6/MUC1 was found in all pancreatic cancer tissues,but not in the surrounding normal pancreatic tissues.The expression profile of KL-6/MUC1 was significantly decreased after treatment with the inhibitors.The adhesion and invasive ability of cancer cells were significantly decreased after drug treatment,and increased E-cadherin and decreased vimentin expression were found.CONCLUSION:KL-6/MUC1 glycosylation is involved in pancreatic cancer metastasis and invasion.Therapeutic strategies which target this may help control the aggressive behavior of pancreatic cancer cells.     

A targeted mutation in the mouse E-cadherin gene results in defective preimplantation development.

The Ca(2+)-dependent cell adhesion molecule E-cadherin functions in the establishment and maintenance of epithelial cell morphology during embryogenesis and adulthood. Downregulation or complete shut-down of E-cadherin expression and mutation of the gene are observed during the progression of tumors of epithelial origin (carcinomas) and correlate with the metastatic potential. We have introduced a targeted mutation into the E-cadherin gene by homologous recombination in mouse embryonic stem cells. The mutation removes E-cadherin sequences essential for Ca2+ binding and for adhesive function. These embryonic stem cells were used to generate mice carrying the mutation. Heterozygous mutant animals appear normal and are fertile. However, the homozygous mutation is not compatible with life: E-cadherin -/- embryos show severe abnormalities before implantation. Particularly, the adhesive cells of the morula dissociate shortly after compaction has occurred, and their morphological polarization is then destroyed. Interestingly, the blastomers are still able to form desmosomes and tight junctions at sites of distorted cell-cell contact. Thus, maternal E-cadherin suffices for initial compaction of the morula but not for further preimplantation development to occur.     

Endothelial adhesion of synchronized gastric tumor cells changes during cell cycle transit and correlates with the expression level of CD44 splice variants

AIM: To study adhesion capacity and CD44 expression of human gastric adenocarcinoma MKN45 cells at different stages of a first cell cycle. METHODS: MKN45 cells were synchronized by aphidicolin and assayed for adhesion to an endothelial cell (HUVEC) monolayer. Surface expression of CD44 and CD44 splice variants on MKN45 cells was evaluated by flow cytometry. Functional relevance of CD44 adhesion receptors was investigated by blocking studies using anti CD44 monoclonal antibodies or by hyaluronan digestion. RESULTS: Adhesion of MKN45 to HUVEC was increased during G2/M transit, after which adhesion returned to baseline levels with cell cycle completion. In parallel, CD44 splice variants CD44v4, CD44v5, and CD44v7 were all up-regulated on MKN45 during cell cycle progression with a maximum effect in G2/M. The function of CD44 surface receptors was assessed with specific receptor blocking monoclonal antibodies or removal of hyaluronan by digestion with hyaluronidase. Both strategies inhibited tumor cell adhesion to HUVEC by nearly 50%, which indicates that MKN45-HUVEC-interaction is CD44 dependent. CONCLUSION: CD44 expression level is linked to the cell cycle in gastrointestinal tumor cells, which in turn leads to cell cycle dependent alterations of their adhesion behaviour to endothelium.     

Presenilin-1 binds cytoplasmic epithelial cadherin, inhibits cadherin/p120 association, and regulates stability and function of the cadherin/catenin adhesion complex

Here we show that presenilin-1 (PS1), a protein involved in Alzheimer's disease, binds directly to epithelial cadherin (E-cadherin). This binding is mediated by the large cytoplasmic loop of PS1 and requires the membrane-proximal cytoplasmic sequence 604-615 of mature E-cadherin. This sequence is also required for E-cadherin binding of protein p120, a known regulator of cadherin-mediated cell adhesion. Using wild-type and PS1 knockout cells, we found that increasing PS1 levels suppresses p120/E-cadherin binding, and increasing p120 levels suppresses PS1/E-cadherin binding. Thus PS1 and p120 bind to and mutually compete for cellular E-cadherin. Furthermore, PS1 stimulates E-cadherin binding to beta- and gamma-catenin, promotes cytoskeletal association of the cadherin/catenin complexes, and increases Ca(2+)-dependent cell-cell aggregation. Remarkably, PS1 familial Alzheimer disease mutant DeltaE9 increased neither the levels of cadherin/catenin complexes nor cell aggregation, suggesting that this familial Alzheimer disease mutation interferes with cadherin-based cell-cell adhesion. These data identify PS1 as an E-cadherin-binding protein and a regulator of E-cadherin function in vivo.     

Expression of E-cadherin,alpha-and beta-catenins in patients with pancreatic adenocarcinoma

Background/Aims: E-Cadherin and its associated cytoplasmic proteins, catenins, are important mediators of epithelial cell-cell adhesion and intracellular signaling. Much evidence exists suggesting a tumor invasion suppressor role for E-cadherin and catenins and loss of expression, as well as mutations, has been described in a number of epithelial cancers. The aim of this study was to evaluate the expression of E-cadherin and catenins in pancreatic adenocarcinoma tissue, and to examine the relationship between these expression and various clinicopathological parameters. Methods: In this study, we conducted an immunohistochemical investigation of expression of E-cadherin, α- and β-catenins in 30 tissue samples obtained from pancreatic ductal adenocarcino-ma patients undergoing surgical treatment. Results: In the pancreatic mucosa of noncancerous areas, epithelial cells showed equally strong membranous expression of E-cadherin, α- and β-catenin proteins at the cell-cell boundaries. Reduced expression of E-cadherin, α- and β-catenins was demonstrated in 60.0, 40.0, and 56.7% of cancer tissues, respectively. Reduced expression of E-cadherin, α- and β-catenins correlated with tumor dedifferentiation (p = 0.012, 0.013, and 0.033, respectively). Reduced expression of E-cadherin correlated with stage and lymph node involvement (p = 0.031, 0.009, respec-tively). α-Catenin and β-catenin expression did not correlate with the patient's age and sex, with the tumor size, location, stage and depth of invasion, or lymph node involvement and distant metastasis. Conclusion: These results suggest that the E-cadherin and catenins may be a useful marker of differentiation and prognosis in pancreatic adenocarcinoma, although the mechanisms underlying changes in E-cadherin and catenin expression are not fully known.