Overexpression of the M2 isoform of pyruvate kinase is an adverse prognostic factor for signet ring cell gastric cancer

Figure 1 Expression level of the M2 isoform of pyruvate kinase mRNA by gene expression microarray. A: The M2 isoform of pyruvate kinase (PKM2) up-regulation in the 18 primary gastric cancers compared to gastric adjacent noncancerous tissues paired from the same patient (P < 0.001); B: PKM2 up-regulation in the 22 differentiated type (D) gastric cancers compared to 27 undifferentiated type (UD) gastric cancers (P < 0.001). The column and bar represent mean and standard deviation, respectively.

Figure 2 Representative images from immunohistochemistry assays of 368 archived gastric cancer cases at 20 × 10 magnification. A: Moderately differentiated adenocarcinoma and negative for the M2 isoform of pyruvate kinase (PKM2) expression; B: Signet ring cell carcinoma and negative for PKM2 expression; C: Moderately differentiated adenocarcinoma and positive for PKM2 expression; D: Signet ring cell carcinoma and positive for PKM2 expression.

Figure 3 Recurrence-free survival (A) and overall survival (B) curves according to the M2 isoform of pyruvate kinase expression in signet ring cell gastric cancer after curative resection (n = 79). Positive M2 isoform of pyruvate kinase (PKM2) expression, real line; Negative PKM2 expression, dotted line.