Multi-site sequencing supports dual-track evolution and identifies candidate metastasis-associated factors in gastric cancer ovarian metastasis.

Abstract

Background: Gastric cancer ovarian metastasis (GCOM) is an aggressive clinical entity whose evolutionary dissemination routes and molecular features remain incompletely defined.

Methods: We performed whole-exome sequencing and patient-level phylogenetic reconstruction of 81 spatially distinct tumour specimens from 17 patients with GCOM.

Results: Ovarian metastases showed a higher tumour mutational burden than matched primary tumours and substantial inter-lesional genomic heterogeneity. Phylogenetic reconstruction supported two major evolutionary routes of ovarian dissemination: lymph node-dependent evolution, in which ovarian metastases were phylogenetically associated with lymph node-related lineages, and lymph node-independent evolution, in which ovarian and lymph node metastases diverged along separate branches. Putative driver-gene alterations were relatively enriched in the shared/truncal mutational fraction, and SCAF4 emerged as an understudied candidate metastasis-associated factor. In GC cells, SCAF4 depletion was accompanied by widespread alterations in RNA splicing and interferon-related transcriptional programs and enhanced proliferative, migratory, invasive, and clonogenic phenotypes.

Conclusions: These findings support a dual-route evolutionary framework for GCOM and nominate SCAF4 as a candidate metastasis-associated factor, providing a genomic basis for understanding the biological heterogeneity of ovarian dissemination in GC.

Highlights: A multi-site genomic sequencing and phylogenetic reconstruction in matched gastric primaries and ovarian metastases was performed. Uncovered two distinct evolutionary routes for gastric cancer ovarian metastasis: lymph node-dependent and lymph node-independent evolutionary patterns. Genomic and functional analyses nominate SCAF4 as a candidate metastasis-associated factor.