Comparative transcriptome characterization of paired primary gastric cancer and ovarian metastasis

To understand the molecular mechanism underlying ovarian metastasis of gastric cancer, we performed RNA-seq of paired primary tumor, normal mucosa and ovarian metastasis of four GC patients by the Illumina sequencing platform with 150-bp paired-end, followed by functional enrichment analyses of differentially expressed genes between three sample sets. A total number of 15,493 protein-coding genes were detected, the majority of which were the annotated human reference genes. Using a threshold of fold change >2 and adjusted P value <0.05, a total number of 3023 differentially expressed genes were detected between different sets of samples. Among them, 479 and 609 protein-coding genes were up- and down-regulated in ovarian metastases over primary tumors, respectively. Functional enrichment analyses revealed the significant enrichment of immune system, tumor microenvironment, metabolism and sex hormone-related pathways in the ovarian metastasis of gastric cancer. In conclusion, comparative transcriptome characterization of paired primary and ovarian metastatic tumor profiled the genome-wide molecular expression and unveiled functionally enriched pathways underlying this specific type of distant metastasis in GC. Overall design: RNA profiling of triple-matched primary gastric cancer, normal mucosae and ovarian metastasis by deep sequencing using Illumina NovaSeq .