The clinicopathological and molecular analysis of gastric cancer with altered SMARCA4 expression

Shih Chiang Huang, Kwai Fong Ng, Ta Sen Yeh, Chi Tung Cheng, Min Chi Chen, Yi Chun Chao, Huei Chieh Chuang, Yu Jen Liu, Tse Ching Chen*

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

35 Scopus citations

Abstract

Aims: In this study, we examine the clinicopathological and molecular features of gastric cancer (GC) with SMARCA4 alterations. Methods and results: We screened SMARCA4 alterations using immunohistochemistry on 1199 surgically resected GCs with information on Epstein–Barr virus (EBV), microsatellite instability (MSI) and other SWI/SNF subunits. SMARCA4, SMARCA2 and ARID1A mutations were investigated by targeted sequencing. The clinicopathological significance was determined by statistical analysis. Twenty-seven cases (2%) with altered SMARCA4 expression were identified, exhibiting completely lost (six), reduced (nine) or heterogeneous (12) patterns. Frequent concomitant alterations of other SWI/SNF subunits were noted with an unusual discordant spatial heterogeneity. In comparison with SMARCA4-retained GCs, SMARCA4-lost GCs were observed more frequently in the non-EBV/MSI subgroup (five of six) and reduced or heterogeneous SMARCA4 expression mainly occurred in EBV- or MSI-associated cases (six of nine and six of 12, respectively; P < 0.001). Histologically, SMARCA4-altered GC, irrespective of expression pattern, demonstrated divergent histomorphology, spanning tubular, poorly cohesive or mixed, neuroendocrine to solid and undifferentiated carcinoma, with a predilection to the latter two (P < 0.001). De-differentiation-like transition and rhabdoid features were noted in a minority of cases. For overall survival, altered SMARCA4 expression was an unfavourable prognostic factor in stage III, EBV-associated GC and non-EBV/MSI intestinal subtype (P ≤ 0.001). SMARCA4 or ARID1A mutations were detected mainly in SMARCA4-lost or reduced GC, respectively. Conclusions: SMARCA4-altered GCs are rare and have intratumoral heterogeneity, histomorphological diversity, conditional prognostic significance and various genetic drivers. SMARCA4-lost GC may represent a genuine SMARCA4-deficient neoplasm, but most SMARCA4-reduced/heterogeneous cases are secondary to ARID1A collapse or associated with different genotypes.

Original languageEnglish
Pages (from-to)250-261
Number of pages12
JournalHistopathology
Volume77
Issue number2
DOIs
StatePublished - 01 08 2020

Bibliographical note

Publisher Copyright:
© 2020 John Wiley & Sons Ltd

Keywords

  • Epstein–Barr virus
  • SMARCA4
  • SWI/SNF
  • gastric cancer
  • microsatellite instability

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