Metastatic pathway-specific transcriptome analysis identifies MFSD4 as a putative tumor suppressor and biomarker for hepatic metastasis in patients with gastric cancer

Gastric cancer (GC) with hepatic metastasis remains a fatal disease. Global expression profiling was conducted using tissues from patients who had GC with synchronous hepatic metastasis, and major facilitator superfamily domain containing 4 (MFSD4) was identified as a candidate biomarker for hepatic metastasis in GC. Functional and expression analyses of this molecule in GC cell lines and clinical samples were conducted. We analyzed MFSD4 expression, DNA methylation, and copy number. RNA interference experiments evaluated the effects of MFSD4 expression on cell phenotype and apoptosis. We analyzed tissues of 200 patients with GC to assess the diagnostic performance of MFSD4 levels for predicting hepatic recurrence, metastasis, or both. Differential expression of MFSD4 mRNA by GC cell lines correlated positively with the levels of NUDT13 and OCLN mRNAs and inversely with those of BMP2. Hypermethylation of the MFSD4 promoter was detected in cells with lower levels of MFSD4 mRNA. Inhibition of MFSD4 expression significantly increased the invasiveness and motility of GC cells but did not influence cell proliferation or apoptosis. MFSD4 mRNA levels in primary GC tissues were reduced in patients with concomitant hepatic metastasis or recurrence compared with those without. Low levels of MFSD4 mRNA in primary GC tissues were an independent risk factor of hepatic recurrence and metastasis. MFSD4 expression in gastric tissues may represent a useful biomarker for identification of patients at high risk for hepatic recurrence, metastasis, or both.