Autoantibodies against MMP-7 as a novel diagnostic biomarker in esophageal squamous cell carcinoma

Figure 1 Double endonuclease digestion of the recombinant vector pET-28b/matrix metalloproteinase-7. M: DNA maker; Lane 1: Double digestion with NdeI and HindIII; Lane 2: Positive bacterial clone.

Figure 2 pET-28b/matrix metalloproteinase-7 protein expression by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Panel A: Time course analysis of pET-28b/matrix metalloproteinase-7 (MMP-7) protein expression by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). M: Protein marker; 1-5: Samples for different time points (1, 2, 4, 6, and 7 h) at 37°C after 0.4 mmol/L IPTG induced; 6: Uninduced bacterial lysate. Panel B: SDS-PAGE showing pET-28b/MMP-7 protein expression induced by different amounts of IPTG. 1, 5: Uninduced bacterial lysate; 2-4: Samples induced at different concentrations of IPTG (0.4, 0.8, 1 mmol/L) at 37°C for 4 h; 6-8: Samples induced at different concentrations of IPTG (0.4, 0.8, 1 mmol/L) at 28°C for 4 h.

Figure 3 Soluble analysis and purification. 1: Samples induced with IPTG (0.4 mmol/L) for 4 h at 37°C; 2: Precipitate from the lysate of pET-28b/matrix metalloproteinase-7 (MMP-7) induced by IPTG; 3: The lysate supernatant of pET-28b/MMP-7 induced by IPTG; 4: Uninduced bacterial lysate; 5-6: Purified recombinant protein.

Figure 4 Comparison of the specificity and sensitivity of matrix metalloproteinase-7 autoantibodies. A: matrix metalloproteinase-7 (MMP-7) autoantibodies were detected by enzyme-linked immunosorbent assay (ELISA) in sera from patients with esophageal squamous cell carcinoma (ESCC) and control samples (Control); B: MMP-7 autoantibodies were detected by ELISA in sera from patients with gastric cancer (Gastric cancer patients) and controls (Control); C: ROC curve for ESCC serum antibodies against MMP-7; D: ROC curve for gastric cancer serum antibodies against MMP-7.