MicroRNAs as a potential prognostic factor in gastric cancer

Figure 5 Validation by quantitative real-time polymerase chain reaction A: Differential expression of microRNAs (miRs) between a subset of the gastric cancer samples from patients with good prognosis (n = 10) or bad prognosis (n = 10). Median expression data are shown for all probes tested. Cycle threshold (C_T) values are the inverses of the log signals; therefore, median values are given in 50-C_T (50_CT) to maintain the same sense as the array data; B: Correlation of expression signals of miR-451 between microarrays (log₂ normalized fluorescence units) and quantitative real-time polymerase chain reaction (qRT-PCR) (50_CT). Good-prognosis cases are represented by filled circles, bad-prognosis cases by empty squares. Dotted lines indicate the thresholds of the miR-451 signal at normalized fluorescence of 181 units [log₂(181) = 7.5] and at 50_CT = 19. The correlation coefficient (Pearson) between the signals is 0.83; C: Recurrence in 20 cases, measured by qRT-PCR, grouped by 50_CT < 19 (solid line, n = 5) or 50_CT > 19 (dotted line, n = 15). P = 0.015 by log-rank test. MiR: MicroRNA; PCR: Polymerase chain reaction; HM: Human custom microRNA-Microarray.