Initial and crucial genetic events in intestinal-type gastric intramucosal neoplasia.
Gastric cancer (GC) is one of the most common and life-threatening malignancies. The course of disease and tumor aggressiveness vary among GCs, although how early fate is determined and by what factors remains elusive. To solve this question, we collected 43 gastric intramucosal neoplasias (GINs), comprising dysplasia/intraepithelial neoplasia (D/IEN; a premalignant lesion) and minute GC (miGC; ≤10 mm) of intestinal histotype and performed targeted deep DNA sequencing of 67 GC-related genes derived from large-scale data. Gastric D/IEN was classified into low or high grade (LG-D/IEN or HG-D/IEN). The most frequent mutations in D/IENs included APC (19/25; 76%), ARID2 (6/25; 24%) and MUC6 (5/25; 20%). All LG-D/IENs had APC mutation (12/12) and APC hotspot mutations affecting R1450 and E1554 were noted in both LG-D/IEN and HG-D/IEN. ARID2 mutation always co-occurred with APC mutation, whose tumor variant allele frequency (TVAF) was higher than that of ARID2 in D/IEN. APC and TP53 mutations were mutually exclusive in D/IEN (p = 0.031 [main cohort], p = 0.025 [expanding cohort]) and TP53-mutated D/IEN was exclusively HG-D/IEN (4/4). TP53 mutations were highly recurrent (11/14; 79%) in MLH1-positive miGCs and were detected even in two microscopic lesions measuring 1 and 3 mm, respectively. Furthermore, TVAF analyses suggested that TP53 mutation is the initial event in the TP53-mutated miGCs. In contrast, TP53 mutation was absent (0/4) in MLH1-negative small intramucosal carcinoma (8-24 mm). Advanced GC data suggested that early mutations (APC and TP53) may affect the potential of cancerous progression from D/IEN. This study revealed somatic mutational landscape and initial mutations of GINs, and we report for the first time that TP53 mutations precede other mutations in intestinal-type GC. Our results also indicate that molecular subtyping based on APC/TP53 mutations would be a high-priority approach for determining and predicting the malignant potential of GIN, including D/IEN. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
['Rokutan|Hirofumi|H|0000-0003-4172-4892', 'Abe|Hiroyuki|H|', 'Nakamura|Hiromi|H|', 'Ushiku|Tetsuo|T|', 'Arakawa|Erika|E|', 'Hosoda|Fumie|F|', 'Yachida|Shinichi|S|', 'Tsuji|Yosuke|Y|', 'Fujishiro|Mitsuhiro|M|', 'Koike|Kazuhiko|K|', 'Totoki|Yasushi|Y|', 'Fukayama|Masashi|M|', 'Shibata|Tatsuhiro|T|']
D000368:Aged D000369:Aged, 80 and over D063646:Carcinogenesis D002471:Cell Transformation, Neoplastic D005260:Female D005753:Gastric Mucosa D017491:Genes, APC D059014:High-Throughput Nucleotide Sequencing D006801:Humans D019656:Loss of Heterozygosity D008297:Male D008875:Middle Aged D009154:Mutation D011230:Precancerous Conditions D013274:Stomach Neoplasms D016159:Tumor Suppressor Protein p53
dysplasia/intraepithelial neoplasia carcinogenesis minute gastric carcinoma mutation profiling