Molecular profiling of hepatoid adenocarcinoma and adenocarcinoma with enteroblastic differentiation.

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.