Motohisa Takami

E‐cadherin gene variants in gastric cancer families whose probands are diagnosed with diffuse gastric cancer

To identify germline E‐cadherin mutations responsible for the predisposition to diffuse gastric cancer (DGC) among the Japanese, we screened 17 patients with familial aggregation of gastric cancer by sequencing analysis. All the patients were diagnosed with DGC and had at least 1 sibling with gastric cancer. Two novel E‐cadherin gene variants were detected. One was detected in 1 patient only and associated with an amino acid substitution (Val/Met) at codon 832 in the region essential for binding to β‐catenin. The M832 variant was detected not only in the proband but also in 2 other gastric cancer patients in the family. Immunohistochemical analysis of gastric cancer tissue from the proband revealed that E‐cadherin expression was markedly reduced and β‐catenin expression was also reduced in cancer cells. However, no significant difference in the activity of β‐catenin binding was detected between the M832 variant and V832 wild‐type E‐cadherin in immunofluorescence and immunoprecipitation/Western blot analyses. The other was detected in 5 patients and was located in the splice donor site (IVS1+6T/C); however, RT‐PCR analysis indicated that the IVS+6C variant did not cause an aberrant splicing. Thus, the M832 variant could be a germline mutation causative of familial aggregation of DGC, although further functional studies are needed to understand the pathogenic significance of this variant.

Studies on pyridoxine deficiency in rats.

Summary The activity of pyridoxal phosphate-dependent enzymes was investigated in pyridoxine deficiency. Depression of the activity was most pronounced in serine and homoserine dehydratase, whereas the level of serine hydroxymethylase was not changed. Regeneration of liver after partial hepatectomy in pyridoxine deficiency proceeded at the normal rate as measured by the increase in weight and the amounts of protein, RNA and DNA of the regenerating tissue. The rate of incorporation of thymidine-3H was also unchanged. In pyridoxine deficiency, the incorporation of radioactivity from serine-3-14C into DNA of the regenerating tissue was essentially the same as in the control. This finding together with the resistance of serine hydroxymethylase to the deficiency indicate that the formation of C1 units from serine is not impaired.

Novel germline mutations of hMSH2 in a patient with hereditary nonpolyposis colorectal cancer (HNPCC) and in a patient with six primary cancers

AbstractWe screened for germline mutations of mismatch repair genes, hMLH1 and hMSH2, in five Japanese families carrying hereditary nonpolyposis colorectal cancer (HNPCC) and in a patient with multiple primary cancers. Screening the entire coding regions of both genes using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, we found two novel germline mutations in hMSH2. One was a 1-bp insertion in exon 12, detected in a patient who had undergone surgery six times for independent tumors (four primary colorectal carcinomas, a small intestinal carcinoma, and an endometrial cancer). The other, in a second patient, was a missense mutation from CTT to TTT at codon 390 in exon 7 that resulted in substitution of phenylalanine for leucine. This conservative alteration was not found in any of 50 normal controls, but we cannot exclude the possibility that it may represent a rare polymorphism rather than a factor in the disease.

Evaluation of effectiveness of chemotherapy in patients with gastric cancer after curative resection

AbstractBackground. A prospective randomized study involving gastric cancer patients was undertaken to evaluate combined adjuvant chemotherapy and the prognostic value of biologic markers. Methods. One hundred and eighty-five patients under 75 years of age who underwent a curable resection of pathologic stage II or III gastric cancer were randomly assigned to receive adjuvant chemotherapy containing either: mitomycin C (MMC) plus oral 5-fluorouracil (FU) (MF), epirubicin plus oral FU (EF), or oral FU (F). Tumor tissue collected at surgery was immunohistochemically analyzed for p53 and proliferating cell nuclear antigen, and DNA ploidy was determined. Results. All prognostic factors were equally distributed in each arm. There was no significant difference among the groups in the 5-year overall survival. When the relationship between the biologic markers and prognosis was analyzed, the overall survival of all patients and stage III patients was poorer in those with p53 positivity, but the difference did not achieve significance. For patients with positive nodes, irrespective of the treatment regimen, p53-positivity was significantly associated with poorer prognosis (P = 0.05). In stage III patients, the survival of those with p53-positivity and DNA aneuploidy was significantly worse than that for patients with any other combination (P = 0.02). Conclusion. No survival benefit was observed with the combined chemotherapeutic regimens compared with FU alone. p53 positivity was negatively correlated to survival for node-positive and stage III patients.