Supplementary table 1 miR-506 expression and clinocopathological factors FactorsTotal number miR-506 low expressionmiR-506 high expression P-value (n = 85)(n = 56) number% % Age (mean ± SD) 65.8 ± ± Gender Male Female Histological grade a, b Well & Moderately Poorly & Undifferentiated Tumor depth T1 and T T3 and T Lymph node metastasis Absent Present Venous invasion Absent Present Peritoneal metastasis Absent Present Stage Ⅰ and Ⅱ Ⅲ and Ⅳ Staging was classified by UICC 7th edition. a Well differentiated adenocarcinoma (Well), Moderately differentiated adenocarcinoma (Moderately), Poorly differentiated adenocar- cinoma (Poorly), Undifferentiated adenocarcinoma (Undifferentiated). b Histological grade of one patient was not avaiable. SD, standard deviation.

Supplementary table 2 SNAI2 expression in immunohistochemical analysis SNAI2 P - value HighLow miR-506 High Low235

Supplementary table 3 Patient backgrounds in this study compared between early and late 10 years. FactorsTotal number P-value (n = 98)(n = 43) number% % Age (mean ± SD) 65.6 ± ± Gender Male Female Histological grade a, b Well & Moderately Poorly & Undifferentiated Tumor depth T1 and T T3 and T Lymph node metastasis Absent Present Venous invasion Absent Present Peritoneal metastasis Absent Present Stage Ⅰ and Ⅱ Ⅲ and Ⅳ Neoadjuvant chemotherapy c Yes No Adjuvant chemotherapy d Yes No Staging was classified by UICC 7th edition. a Well differentiated adenocarcinoma (Well), Moderately differentiated adenocarcinoma (Moderately), Poorly differentiated adenocarcinoma (Poorly), Undifferentiated adenocarcinoma (Undifferentiated). b Histological grade of one patient was not avaiable. c Neoadjuvant chemotherapy of eight patients were not avaiable. d Adjuvant chemotherapy of nine patients were not avaiable. SD, standard deviation.

Supplementary figure 1 Sequences of miR-506 binding sites in the 3′UTRs of transcripts encoding SNAI2.

Relative expression of SNAI2/GAPDH Relative expression of miR-506 MKN-7MKN-1 NUGC-3 P = 0.01 P = 0.02 P < 0.01 Supplementary figure 2 Endogenous miR-506 expression was measured in 3 gastric cancer cell lines. GC cell lines with high endogenous miR-506 expression (MKN-1 and NUGC-3) showed significantly lower SNAI2 expression compared to cells with low endogenous miR-506 expression (MKN-7). MKN-7MKN-1 NUGC-3

Relative expression of miR-506 pre-miR-506 MKN-7 P < 0.05 MKN-45 pre-miR-506 Relative expression of miR nM 50 nM 30 nM 50 nM Supplementary figure 3. miR-506/RNU6B expression as measured by quantitative real-time PCR analysis in MKN7 cells (left) and MKN45 cells (right) after transfection with pre-miR-506. Error bars represent the SD from three replicates. Abbreviations: NC, pre-miR negative control; 30 nM, pre-miR nM; 50 nM, pre-miR nM. P < 0.05

Supplementary figure 4 The expression levels of SNAI2 were evaluated by scoring four classes (0, 1+, 2+, and 3+). Scale bar: 50 μm SNAI2