miRNA and Gemcitabine Response FIG. 1 Correlation between the expression levels of miR- 142-5p identiﬁed by miRNA expression proﬁling and the prognosis of patients with resected pancreatic cancer in the gemcitabine and nongemcitabine groups. The levels of miRNA expression were normalized against RNU6B. High miR-142-5p expression was signiﬁcantly associated with longer survival times in the gemcitabine group (P = 0.0077), but not in the nongemcitabine group (P = 0.48) FIG. 2 The correlation between the expression levels of miR-204 identiﬁed by miRNA expression proﬁling and the prognosis of patients with resected pancreatic cancer in the gemcitabine and nongemcitabine groups. The levels of miRNA expression were normalized against RNU6B. High miR-204 expression was signiﬁcantly associated with longer survival times in the gemcitabine group (P = 0.0054), but not in the nongemcitabine group (P = 0.15) a a b b 2385 TABLE 2 Correlation between median overall survival and micr- oRNA expression in patients with resected pancreatic cancer Factor Overall survival (95% CI) P value signiﬁcant differences in survival between the high and low miR-9, miR-27a, miR-424, and miR-449b patients in the gemcitabine and nongemcitabine groups (data not shown). miR-142-5p Gem group Non-Gem group miR-204 Gem group Non-Gem group miR-125a Gem group Non-Gem group miR-34a Gem group Non-Gem group High 45 (23–) 13.07 (4.7–43) 33 (13.27–) 13.07 (8.47–26) 30.17 (19–) 12 (8.47–16.93) 27 (20.87–47.9) 16.9 (9–24.4) Low 16.3 (12–23) 11 (7.7–14.7) 16.3 (12–23) 9 (4–14.7) 14.57(12–31) 14(3–) 16.3 (12–) 8.5 (3–12) 0.0077 0.4880 0.0054 0.1527 0.0854 0.8990 0.1754 0.0127 CI conﬁdence interval, Gem gemcitabine survival time was 16.9 months in the high miR-34a patients and 8.5 months in the low miR-34a patients in the nongemcitabine group (Table 2). We also found no Multivariate Analysis of miR-142-5p and miR-34a Expression in Relation to Survival Time of Patients with or without Gemcitabine Treatment after Curative Resection In three miRNAs identiﬁed as potential prognostic markers in the gemcitabine group, miR-142-5p was the best candidate and was the most speciﬁc for the gemcitabine group compared with the nongemcitabine group. Therefore, we focused on miR-142-5p as the most promising predic- tive marker for gemcitabine. Also, univariate analysis of the gemcitabine group showed that the only signiﬁcant clinical factors were pN status (pN1 vs. pN0), and R factor (R1 vs. R0). Multivariate survival analysis, based on the Cox pro- portional hazard model, was performed by using miR-142- 5p expression (high versus low), pN status, and R factor. Overall survival time was signiﬁcantly dependent on miR- 142-5p expression (Table 3, P = 0.034), but not on pN