Identification and characterization of a novel germ line p53 mutation in familial gastric cancer in the Japanese population

Abstract

Germ line mutations of the p53 gene are known to cause Li-Fraumeni syndrome, and a germ line p53 mutation has recently been reported in a small subset of familial gastric cancer (FGC) in Europe and Korea. Although the incidence of gastric cancer is very high in Japan and familial clustering is not uncommon, there has been little information on the genetic factors of FGC. Therefore, to determine the role of germ line p53 mutations in FGC in the Japanese population in this study, we used sequencing analysis to examine 80 individuals from 35 Japanese FGC families without germ line CDH1 mutations for germ line p53 mutations. One missense (c.91G>A: p.Val31Ile) and two intronic germ line mutations were found, and transcriptional activity of the Ile31 mutant on p53-responsive genes was examined to determine the functional effect of the novel p.Val31Ile germ line mutation. A luciferase reporter assay showed that the transcriptional activity of p21 (CDKN1A) and MDM2 promoters but not of the BAX promoter was significantly lower in the Ile31-type p53 than in the wild-type (wt) p53. Next, doxycycline-regulated p53-inducible H1299 cell lines were established by applying a retrovirus-mediated gene transfer system to a p53-null human H1299 cell line. Under similar p53 expression conditions shown by western blot and immunofluorescence analyses, a cell proliferation assay showed that the Ile31-type p53 had significantly lower cell proliferation suppressing activity than wt p53. These results suggest that Ile31-type p53 may be partly involved in FGC because of its low transcriptional activity and low cell proliferation suppressing activity.

Genomic landscape and genetic heterogeneity in gastric adenocarcinoma revealed by whole-genome sequencing

“…This is a known variant implicated in hereditary diffuse-type GC. Two patients (T10 and T18) with diffuse-type GC had TP53 germline variant 91G4A (heterozygous in both PBMC and tumour, corresponds to p. Val31Ile), which is previously reported in GC associated with Li Fraumeni syndrome 22 . Sample T10 had no other somatic mutation in TP53; however, T18 harboured somatic nonsense mutation of TP53.…”

Identification and characterization of a novel germline p53 mutation in a patient with glioblastoma and colon cancer

“…10 Luciferase reporter assay p53-null human H1299 cells were transiently cotransfected with the p53 expression vector, firefly luciferase reporter vector pGL4.10 (Promega, Madison, WI) containing a fragment of the p21 (CDKN1A), BAX or MDM2 promoter and a Renilla luciferase reporter vector pGL4.74 (Promega), and 24 hr after transfection, luciferase activity was measured by a Dual-Luciferase Reporter Assay System (Promega) as described previously. 7 Colony formation assay p53-null H1299 cell lines were transfected with the p53 expression vector using Lipofectamine 2000 reagent (Invitrogen, Carlsbad, CA), followed by selection in media containing G418 antibiotics at 1 mg/ml for 2 weeks. Colonies were fixed, stained and counted.…”

Comparison of patients by family history with gastric and non-gastric cancer

“…Family history of GC has previously been studied in many regions, including eastern Asian [2][3][4][5][6][7][8][9] , North American [10][11][12] , northern European [13][14][15] , and Mediterranean countries [16][17][18][19][20][21] . A much higher incidence of familial GC (FGC) was reported from Mediterranean countries [19] , while a relatively low occurrence was noted in northern European countries [14] .…”