Diagnostic and prognostic value of metastasis inducer S100A4 transcripts in plasma of colon, rectal, and gastric cancer patients

Abstract

Early detection of tumors and metastases is critical for improving treatment strategies and patient outcomes. The development of molecular markers and simple tests that are clinically applicable for detection, prognostication, and therapy monitoring is strongly needed. The gene S100A4 has long been known to act as a metastasis inducer. High S100A4 levels in the primary tumor are prognostic for metachronous metastasis and correlate with reduced patient survival. We provide, for the first time, a plasma-based assay for transcript quantification of S100A4 in gastrointestinal patients' plasma. We conducted a study to define the diagnostic and prognostic power of S100A4 transcripts using 466 plasma samples from colon, rectal, and gastric cancer patients. Plasma was separated, RNA was isolated, and S100A4 mRNA was determined by quantitative RT-PCR. S100A4 transcripts were increased in cancer patients of each entity (P < 0.0001) and all disease stages (P < 0.05), compared with tumor-free volunteers (sensitivities of 96%, 74%, and 90% and specificities of 59%, 82%, and 71%, for colon, rectal, and gastric cancer patients, respectively). Prospectively analyzed follow-up patients who later experienced metastasis showed higher S100A4 levels than follow-up patients without metastasis. Disease-free survival was decreased in high S100A4-expressing follow-up colorectal cancer patients (P = 0.013). In summary, we developed a method for quantitative S100A4 transcript determination in plasma that allows clinical application routinely. We demonstrated the diagnostic and prognostic potential of this method for early defining cancer staging and patients' risk for metastasis.

Figure 1

S100A4 transcripts in plasma of tumor-free volunteers. Box plot analysis, based on quantitative real-time RT-PCR (Tables 1–3). No different S100A4 transcript levels were found in two independently analyzed cohorts of tumor-free volunteers.

Figure 2

S100A4 transcripts in plasma discriminate cancer patients from tumor-free volunteers. Box plot analysis, based on quantitative real-time RT-PCR (Tables 1–3). All patient cohorts with colorectal, colon, rectal, or gastric cancer expressed significantly higher S100A4 transcript levels than healthy volunteers.

Figure 3

S100A4 transcripts in plasma of patients newly diagnosed with a primary tumor without or with synchronous metastasis, or with metachronous metastasis. Box plot analysis, based on quantitative real-time RT-PCR (Tables 1–3). All patients' subcohorts with colon (A), rectal (B), and gastric (C) cancer expressed significantly higher S100A4 transcript levels than healthy volunteers. Significantly different S100A4 levels were also found for colon (A) patients of stages I–III versus IV, and for colon cancer patients without and with metachronous metastasis (A).

Figure 4

S100A4 transcripts in plasma of follow-up cancer patients without or with distant metastases. Box plot analysis, based on quantitative real-time RT-PCR (Tables 1–3). All follow-up patient subcohorts with nonmetastasized or metastasized colon (A), rectal (B), and gastric (C) cancer expressed significantly higher S100A4 transcript levels than healthy volunteers. Significantly different S100A4 levels were also found for rectal (B) follow-up patients without versus with metastasis; higher S100A4 levels were determined in patients with metastasized colon (A) and gastric (C) cancer compared with patients without metastasis.

Figure 5

S100A4 transcripts in plasma of follow-up cancer patients and DFS. A: Kaplan–Meier analysis for DFS of all follow-up colorectal cancer patients (n = 288, Tables 1 and 2). Based on the median (0.387 S100A4 mRNA expression, % calibrator), all follow-up patients were subclassified into S100A4 transcript low (below median; n = 145) and high (above median; n = 143) expressors. DFS was significantly decreased in patients with high S100A4 transcript levels (P = 0.013). B: Kaplan-Meier analysis for DFS of all follow-up gastric cancer patients (n = 64, Table 3). Based on the median (0.39 S100A4 mRNA expression, % calibrator), all follow-up patients were subclassified into S100A4 transcript low (below median; n = 32) and high (above median; n = 32) expressors.