High-throughput mutation profiling identifies novel molecular dysregulation in high-grade intraepithelial neoplasia and early gastric cancers

Abstract

Background There is still no widely accepted molecular marker available to distinguish between gastric high-grade intraepithelial neoplasia (HG-IEN) and invasive early gastric cancer (EGC). Methods HG-IEN and EGC lesions coexisting in the same patient were manually microdissected from a series of 15 gastrectomies for EGC; 40 ng DNA was used for multiplex PCR amplification using the Ion AmpliSeq Cancer Panel, which explores the mutational status of hotspot regions in 50 cancer-associated genes. Results Of the 15 EGCs, 12 presented at least one somatic mutation among the 50 investigated genes, and 6 of these showed multiple driver gene somatic mutations. TP53 mutations were observed in 9 cases; APC mutations were identified in 3 cases; and ATM and STK11 were mutated in 2 cases. Seven HG-IEN lesions shared an identical mutational profile with the EGC from the same patient; 13 mutations observed in APC, ATM, FGFR3, PIK3CA, RB1, STK11, and TP53 genes were shared by both HG-IEN and ECG lesions. CDKN2A, IDH2, MET, and RET mutations were observed only in EGC. TP53 deregulation was further investigated in an independent series of 75 biopsies corresponding to all the phenotypic lesions occurring in the EGC carcinogenetic cascade. p53 nuclear immunoreaction progressively increased along with the dedifferentiation of the lesions (P \ 0.001). Overall, 18 of 20 p53-positive lesions showed a TP53 mutated gene. Discussion Our results support the molecular similarity between HG-IEN and EGC and suggest a relevant role for TP53 in the progression to the invasive phenotype and the use of immunohistochemistry as a surrogate to detect TP53 gene mutations.

Mixed Adenoneuroendocrine Carcinomas of the Gastrointestinal Tract: Targeted Next-Generation Sequencing Suggests a Monoclonal Origin of the Two Components

“…As previously described for other tumor types [20,30,31], our results further support the clinical impact of targeted NGS on routinely processed samples. The integration of the mutational profiles with morphological and immunophenotypic data depicts a next-generation type of histopathological diagnosis.…”

“…In the negative case (case 4), the immunohistochemical negativity may be explained by the fact that the R209 stop mutation likely prevents p53 stabilization, as reported for other similar mutations in TP53 [20]. An example of TP53 mutational results from paired samples is shown in figure 2.…”

“…The immunohistochemical expression of p53 (clone DO-1; prediluted; Immunotech) and β-catenin (clone 15B8; 1:150; Sigma) was tested as a surrogate validation of deep sequencing results, and performed as described elsewhere [20,21]. …”

Role of the Wnt/β-catenin pathway in gastric cancer: An in-depth literature review

“…Moreover, a number of recently published studies exploring gene mutations in gastric cancer using high-throughput methodologies (Nextgeneration sequencing and genotyping array) have confirmed CTNNB1 (the gene that encodes b-catenin protein) and APC as driver genes. Although with variations in prevalence, these studies revealed somatic mutations in both genes that might be relevant in gastric carcinogenesis [50][51][52][53][54][55] . In addition to multiple genetic alterations, the initiation and progression of gastric cancer are also associated to epigenetic changes [56,57] .…”

Epithelial dysplasia of the stomach with gastric immunophenotype shows features of biological aggressiveness

“…HER2 immunoexpression was scored according to Rüsc-hoff et al [12]: 0, absence of immunoreactivity; 1?, tumor cell cluster with faint or barely perceptible membrane reactivity irrespective of percentage of immunoreactive cells; 2?, tumor cell cluster with weak to moderate (complete, lateral, or basolateral) reactivity irrespective of the percentage of immunoreactive cells; 3?, tumor cell cluster with strong (complete, lateral, or basolateral) reactivity irrespective of the percentage of immunoreactive cells; for scoring purposes any nuclear or cytoplasmic background staining was disregarded. The immunoexpression of CDX2 was considered positive when C25 % of the dysplastic cells displayed immunoreactivity [9]; immunoexpression of Ki-67 and TP53 was classified as absent/low when immunoreactivity was displayed in \50 % of the dysplastic cells and high in the presence of C50 % positive cells [13].…”