Hitoshi Shiozaki

E-cadherin mediated adhesion system in cancer cells

Cadherins are the family of functionally related transmembrane glycoproteins responsible for the Ca2+‐dependent cell–cell adhesion mechanism that is crucial for the mutual association of vertebrate cells. Because cell dissociation and acquisition of cell motility occur in cancer invasion and metastasis, it is important to study the possible involvement of mutual cell adhesion of cancer cells.

Effect of epidermal growth factor on cadherin-mediated adhesion in a human oesophageal cancer cell line.

Epidermal growth factor (EGF) mediates many pleiotrophic biological effects, one of which is alteration of cellular morphology. In the present study, we examine the possibility that this alteration in cell morphology is caused in part by the dysfunction of cadherin-mediated cell-cell adhesion using the human oesophageal cancer cell line TE-2R, which expresses E-cadherin and EGF receptor. In the presence of EGF, TE-2R changed its shape from round to fibroblastic and its colony formation from compact to sparse. Vanadate, a tyrosine phosphatase inhibitor, further potentiated the EGF response, whereas herbimycin A, a tyrosine kinase inhibitor, interfered with it. Moreover, EGF enabled the cells to invade in organotypic raft culture. These phenomena were accompanied not by decreased expression of the E-cadherin molecule but by a change in its localisation from the lateral adhesion site to the whole cell surface. Both alpha- and beta-catenin, cadherin-binding proteins, were also expressed at the same level throughout these morphological changes. Finally, we examined tyrosine phosphorylation of E-cadherin and alpha- and beta-catenin, and observed tyrosine phosphorylation of beta-catenin induced by EGF. These results suggest that EGF counteracts E-cadherin-mediated junctional assembly through phosphorylation of beta-catenin and modulates tumour cell behaviour to a more aggressive phenotype.

Immunohistochemical evaluation of alpha-catenin expression in human gastric cancer

E-cadherin (E-cad) plays a major role in the maintenance of cell-cell adhesion in epithelial tissues, and impaired E-cad expression correlates with tumour invasion and metastasis. Alpha-catenin (α-cat), an undercoat protein of adherens junctions, binds to the cytoplasmic domain of E-cad and is essential for linking E-cad to actin-based cytoskeleton. We investigated E-cad and α-cat expression in 60 human gastric cancers immunohistochemically. The 60 gastric cancers were classified into 18 (30%) in which α-cat expression was preserved, and 42 (70%) reduced cases. The reduction of α-cat expression was significantly related to dedifferentiation, depth of invasion, infiltrative growth and lymph node metastasis. We also examined the co-expression of α-cat and E-cad. Seventeen (28%) tumours preserved both molecules [α-cat(+)/E-cad(+)] and 33 (55%) tumours reduced both [α-cat(−)/E-cad(−)], whereas 9 (15%) tumours exhibited α-cat(−)/E-cad(+). The frequency of lymph node metastasis in α-cat(−)/E-cad(+) tumour (67%) was significantly higher than that in α-cat(+)/E-cad(+) tumours (24%) and was close to that in α-cat(−)/E-cad(−) tumours (82%). The frequency of haematogenous liver metastasis in α-cat(−)/E-cad(+) tumours (44%) was significantly higher than that in α-cat(+)/E-cad(+) tumours (6%) or α-cat(−)/E-cad(−) tumours (9%). Thus, in all E-cad(+) tumours, the frequency of lymph node and liver metastasis was higher in α-cat(−) tumours than in α-cat(+) tumours. α-Cat expression is apparently better at predicting tumour invasion and metastasis than E-cad expression.

Aberrant expression and phosphorylation of beta-catenin in human colorectal cancer.

The cytoplasmic domain of cadherins is known to associate with the intracellular proteins, catenins, which link cadherins to the actin-based cytoskeleton. In this study, we immunohistochemically investigated the expression of beta-catenin as well as E-cadherin and alpha-catenin in 86 human colorectal cancers, and we analysed their coexpression pattern and relationship to clinicopathological factors. In cancerous tissues, the frequency of reduced expression of beta-catenin (28 of 86, 33%) was similar to that of E-cadherin (19 of 86, 22%), but less than that of alpha-catenin (47 of 86, 55%). All three molecules were expressed strongly, as was the normal epithelium, in 36 cases (42%), whereas the rest (50 cases, 58%) showed reduction in one of the molecules. The reduction of beta-catenin expression was significantly correlated with dedifferentiation, Dukes stage, lymph node metastasis and liver metastasis. Next, we examined tyrosine phosphorylation in the protein complex immunoprecipitated with E-cadherin, as E-cadherin function is down-regulated by receptor-type tyrosine kinase in vitro. It was of interest that up-regulation of tyrosine phosphorylation of beta-catenin was more frequently observed in cancerous tissues than in the matching normal mucosa. These results suggest that beta-catenin may have important regulatory roles within an E-cadherin-mediated adhesion system in human colorectal cancers.

CYP1A1 CYP2E1 and GSTM1 polymorphisms are not associated with susceptibility to squamous-cell carcinoma of the esophagus

We investigated the genetic polymorphisms of CYPIAI, CYP2EI and GSTMI in Japanese esophageal cancer patients (n = 53) with a histological diagnosis of squamous‐cell carcinoma, to determine whether susceptibility to esophageal cancer is associated with these polymorphisms. There were no significant differences in the frequency distribution of any one of the 3 polymorphisms between esophageal cancer patients and 132 healthy Japanese controls. The genotype distributions in tobacco smokers or alcohol drinkers were also quite similar for male patients and male controls. The age at onset of esophageal cancer was also similar for patients with any genotype of the 3 polymorphisms. We conclude that the 3 polymorphisms are unlikely to be associated with esophageal cancer susceptibility. Int. J. Cancer 71:192–195, 1997.

Prognostic value of dna ploidy in squamous cell carcinoma of esophagus. Analyzed with improved flow cytometric measurement

Background. The prognostic value of flow cytometric DNA analysis on paraffin‐embedded tumor samples has been controversial in esophageal cancer. To clarify its true significance, the authors developed an improved method that excludes the possibility of contamination by lymphocytes in tumor sample.

A newly-designed shape-memory coil stent for esophageal stricture: A preliminary report

A newly designed coil esophageal endoprosthesis was developed using a thermal shape-memory titanium-nickel alloy. The major advantages of this stent lie in (a) its small diameter while in its compressed state in ice water and (b) the large lumen which is achieved once it has been warmed to body temperature. The technical feasibility and tissue compatibility of this stent were tested on four beagle dogs: two with an anastomotic stricture and two with a stenosis induced by the injection of monoethanolamine oleate. The teflon-coated stent was inserted under fluoroscopy and removed 4 weeks after implantation. No signs of esophageal reobstruction were observed in any of the animals after implantation or extraction of the stent, although the dog which had received the first stent without teflon coating developed obstruction caused by granulation tissue. Our preliminary experience strongly suggests that the shape-memory alloy stent with teflon coating may be used in the endoscopic treatment of anastomotic stenosis after esophagectomy, as well as of esophageal obstruction caused by carcinoma.

Immunohistochemical Evaluation of E-Cadherin and α-Catenin Expression in Human Esophageal Cancer

Tumor metastasis is initiated by disaggregation of invasive cells from the primary tumor - a step that requires a breakdown of intercellular adhesion. To investigate the mechanism of dysfunction in cell-cell adhesion of cancerous tissues, we evaluated E-cadherin (E-cad) and α-catenin (α-cat) expression of human esophageal cancer immunohistochemically. Eighty percent of the tumors showed reduced expression of both of the molecules. The frequency of α-cat negative tumors was observed in 47%, but none of them were E-cad negative. These results suggest that esophageal cancers lose α-cat expression more frequently than E-cad, and the loss of α-cat mights cause dysfunction of E-cad-mediated intercellular adhesion.

Correlation Between Expression of E-Cadherin and Metastasis and Invasion in Human Esophageal Cancer

Cadherins are Ca2+-dependent cell-cell adhesion molecules which are possibly involved in the process of metastasis in cancer cells. We have investigated the expression of E-cadherin (E-CD), which is a subclass of cadherin expressed on cell membranes in normal esophageal epithelium. Sixty-two human esophageal cancers were studied with immunoblotting (5 cases) and immunohistochemical staining (62 cases) using monoclonal antibody for human E-CD (HECD-1) on frozen surgical specimens, and the correlation between E-CD expression and incidence of clinical lymph node metastasis and cancer invasion was investigated.