Plasma matrix metalloproteinase 1 improves the detection and survival prediction of esophageal squamous cell carcinoma

Abstract

This study aimed to identify noninvasive protein markers capable of detecting the presence and prognosis of esophageal squamous-cell carcinoma (ESCC). Analyzing microarray expression data collected from 17-pair ESCC specimens, we identified one protein, matrix metalloproteinase-1 (MMP1), as a possibly useful marker. Plasma MMP1 was then measured by enzyme-linked immunosorbent assay (ELISA) in 210 ESCC patients and 197 healthy controls. ESCC patients had higher mean levels of MMP1 than controls (8.7 ± 7.5 vs. 6.7 ± 4.9 ng/mL, p < 0.0001). Using the highest quartile level (9.67 ng/mL) as cut-off, we found a 9.0-fold risk of ESCC in those with higher plasma MMP1 after adjusting for covariates (95% confidence interval = 2.2, 36.0). Heavy smokers and heavy drinkers with higher plasma MMP1 had 61.4- and 31.0 times the risk, respectively, than non-users with lower MMP1. In the survival analysis, compared to those with MMP1 ≤ 9.67 ng/mL, ESCC patients with MMP1 > 9.67 ng/mL had a 48% increase in the risk of ESCC death (adjusted hazard ratio = 1.48; 95% CI = 1.04-2.10). In conclusion, plasma MMP1 may serve as a noninvasive marker of detecting the presence and predicting the survival of ESCC.

Figure 1. Identification of differentially expressed genes from microarray of 17 paired esophageal tissues.

Seven genes were identified to have a fold-change >1.5 and a p-value < 0.005. Their importance on discriminating ESCC from normal tissues was evaluated by the mean decrease in Gini index (MDG) obtained from the Random Forests algorithm. Among the 7 genes, MMP1 ranked number four according to the MDG value.

Figure 2. The nonparametric area under the receiver operating characteristic curve (AUROC) of plasma MMP1 with and without the three major risk factors of ESCC (alcohol drinking, smoking and betel quid chewing).

(A) The AUROC of MMP1 alone was 0.557; the optimal cut-off value was very close to the highest quartile of all study subjects (9.67 ng/mL). (B) Among subjects with any one of the risk factors, adding plasma MMP1 significantly increased the AUROC by 0.0361 (p = 0.0013). (C) Among subjects with any two of the risk factors, adding plasma MMP1 significantly increased the AUROC by 0.0175 (p = 0.0097). (D) Among subjects with all three risk factors, adding plasma MMP1 increased the AUROC by 0.0225 (p = 0.0676).

Figure 3. Comparison of the AUROC before and after adding plasma MMP1 to each risk factor of ESCC (alcohol drinking, smoking and betel quid chewing).

(A) There was a borderline significant difference of AUROC after adding plasma MMP1 to alcohol (difference = 0.0155, p = 0.0719). (B) There was a borderline significant difference of AUROC after adding plasma MMP1 to betel nut (difference = 0.0210, p = 0.0629). (C) adding plasma MMP1 to smoking habit significantly increased the AUROC by 0.0327 (p < 0.0001). (D) After considering all three risk factors, adding plasma MMP1 did not improve discrimination.

Figure 4. Kaplan-Meier survival curve of ESCC patients (N = 176) dichotomized by the cut-off level of plasma MMP1 (9.67 ng/mL).

Patients with plasma MMP1 > 9.67 ng/mL had significantly shorter survival compared to those with lower MMP1 levels (p = 0.0265). Thirty-four patients were excluded for survival analysis because they died (N = 15) or lost follow-up (N = 19) within 1 month of cancer diagnosis.