👤 Masanori Terashima

Hepatoid adenocarcinoma (HAD) and adenocarcinoma with enteroblastic differentiation (ACED) are rare gastric cancer types that produce alpha-fetoprotein (AFP) that morphologically resembles the liver or fetal organ. This study investigated the molecular profiling of HAD and ACED compared with common-type gastric adenocarcinoma (CGA). This study enrolled 496 patients with gastric adenocarcinoma who underwent radical gastrectomy. Whole-exome sequencing and gene expression profiling were conducted to compare HAD/ACED and CGA. Immunohistochemistry was performed in 39 patients with HAD/ACED, including 10 who underwent genomic analysis. TP53 (100 %), CSMD3 (30 %), LRP1B, FAT3, TG, APOB, CREBBP, PASK, DROSHA, and STK40 (20 %) were mutated genes with high frequency (>20 %) in HAD/ACED. Gene expression analysis revealed 15 overexpressed genes in HAD/ACED, many of which were associated with hepatocytes and fetal organs. Furthermore, cancer stemness gene overexpression, including LIN28B, IGF2BP1, and HMGA2, which are related to TP53, was observed. Immunohistochemistry revealed positive staining for LIN28B (82 %), IGF2BP1 (94 %), and HMGA2 (72 %), as well as staining for AFP (69 %), GPC3 (75 %), and SALL4 (94 %). Additionally, positive cancer stemness gene staining was observed in CGA mucosa coexisting with HAD/ACED. HAD/ACED demonstrated higher TP53 mutation accumulation and TP53-related cancer stemness gene overexpression, including LIN28B, IGF2BP1, and HMGA2. Therefore, TP53 and these cancer stemness genes might be involved in the occurrence of HAD/ACED. Show less

Recent reports on gene expression profiling (GEP) show several genes associated with malignant progression of GIST. However, genes associated with malignant transformation have not been clarified. Here, we aimed to reveal distinct genes in aggressive malignant GIST, using comprehensive gene expression analysis. We investigated GEP obtained by microarrays for 43 gastric GISTs, which mostly harbored KIT and PDGFRA mutations and integrated clinicopathological risk information. RT-PCR and immunohistochemistry were performed for FZD7, a receptor of Wnt ligands. GEP divided 43 gastric GISTs into two clusters. A cluster included seven of eight high-risk GISTs (88%) in modified NIH classification and was defined as high-risk cluster; the other cluster was defined as low-risk cluster. The number of probes with over 3-fold changes between the two clusters was 1,177, in which probes corresponding to 16 oncogenes were included. Genes involved in the Wnt signaling pathway were the most abundant among the 16 oncogenes. Focusing on 73 Wnt signaling pathway genes of the 21,578 probes, 12 upregulated and 5 downregulated genes were found in the high-risk cluster. Major cascade genes promoting the Wnt/β-catenin signaling pathway, including WNT11, FZD family, and DVL2, were upregulated in the high-risk cluster. SNAI1, SNAI2, and BIRC5, which are activated by this pathway and increase cell proliferation, were also upregulated. These gene expression alterations were consistent in the positive direction of this pathway. GISTs in high-risk cluster strongly expressed FZD7. Wnt/β-catenin signaling pathway may play an important role in malignant transformation of indolent GIST. Show less

Mutually exclusive KIT and PDGFRA mutations are considered to be the earliest events in gastrointestinal stromal tumors (GIST), but insufficient for their malignant progression. Herein, we aimed to identify driver genes and signaling pathways relevant to GIST progression. We investigated genetic profiles of 707 driver genes, including mutations, gene fusions, copy number gain or loss, and gene expression for 65 clinical specimens of surgically dissected GIST, consisting of six metastatic tumors and 59 primary tumors from stomach, small intestine, rectum, and esophagus. Genetic alterations included oncogenic mutations and amplification-dependent expression enhancement for oncogenes (OG), and loss of heterozygosity (LOH) and expression reduction for tumor suppressor genes (TSG). We assigned activated OG and inactivated TSG to 27 signaling pathways, the activation of which was compared between malignant GIST (metastasis and high-risk GIST) and less malignant GIST (low- and very low-risk GIST). Integrative molecular profiling indicated that a greater incidence of genetic alterations of driver genes was detected in malignant GIST (96%, 22 of 23) than in less malignant GIST (73%, 24 of 33). Malignant GIST samples groups showed mutations, LOH, and aberrant expression dominantly in driver genes associated with signaling pathways of PI3K (PIK3CA, AKT1, and PTEN) and the cell cycle (RB1, CDK4, and CDKN1B). Additionally, we identified potential PI3K-related genes, the expression of which was upregulated (SNAI1 and TPX2) or downregulated (BANK1) in malignant GIST. Based on our observations, we propose that inhibition of PI3K pathway signals might potentially be an effective therapeutic strategy against malignant progression of GIST. Show less

Intracranial germ cell tumours (IGCTs) are a group of rare heterogeneous brain tumours that are clinically and histologically similar to the more common gonadal GCTs. IGCTs show great variation in their geographical and gender distribution, histological composition and treatment outcomes. The incidence of IGCTs is historically five- to eightfold greater in Japan and other East Asian countries than in Western countries, with peak incidence near the time of puberty. About half of the tumours are located in the pineal region. The male-to-female incidence ratio is approximately 3-4:1 overall, but is even higher for tumours located in the pineal region. Owing to the scarcity of tumour specimens available for research, little is currently known about this rare disease. Here we report the analysis of 62 cases by next-generation sequencing, single nucleotide polymorphism array and expression array. We find the KIT/RAS signalling pathway frequently mutated in more than 50% of IGCTs, including novel recurrent somatic mutations in KIT, its downstream mediators KRAS and NRAS, and its negative regulator CBL. Novel somatic alterations in the AKT/mTOR pathway included copy number gains of the AKT1 locus at 14q32.33 in 19% of patients, with corresponding upregulation of AKT1 expression. We identified loss-of-function mutations in BCORL1, a transcriptional co-repressor and tumour suppressor. We report significant enrichment of novel and rare germline variants in JMJD1C, which codes for a histone demethylase and is a coactivator of the androgen receptor, among Japanese IGCT patients. This study establishes a molecular foundation for understanding the biology of IGCTs and suggests potentially promising therapeutic strategies focusing on the inhibition of KIT/RAS activation and the AKT1/mTOR pathway. Show less