Identification of Serum Biomarkers to Monitor Therapeutic Response in Intestinal-Type Gastric Cancer

Abstract

There are a limited number of clinically useful serum biomarkers to predict tumor onset or treatment response in gastric cancer (GC). For this reason, we explored the serum proteome of the gp130^Y757F murine model of intestinal-type gastric cancer (IGC). We identified 30 proteins with significantly elevated expression in early gp130^Y757F IGC and 12 proteins that were significantly elevated in late gp130^Y757F IGC compared to age- and gender-matched wild-type mice. Within these signatures, there was an overlap of 10 proteins commonly elevated in both early- and late-stage disease. These results highlight the potential to identify serum biomarkers of disease stage. Since IGC in the gp130^Y757F model can be reversed following therapeutic inhibition of Interleukin (IL)-11, we explored whether the protein signatures we identified could be used to monitor tumor regression. We compared two different therapeutic modalities and found 5 proteins to be uniquely differentially expressed between control animals and animals halfway through treatment, with 10 differentially expressed at the end of treatment. Our findings highlight the potential to identify reliable biomarkers to track IGC tumor regression in response to treatment.

Keywords: Interleukin-11; biomarker; intestinal-type gastric cancer; mouse model; proteomics.

Figure 1

Identification of early- or late-stage GC serum biomarkers. (A) gp130^Y757F mice with early GC (2 months of age, N = 5 mice per cohort) and gp130^Y757F mice with late GC (6 months of age, N = 3–5 mice per cohort). Scale bar = 6mm. Red arrow = early collection time-point, blue arrow = late collection time-point, black arrows = macroscopic tumor; (B) principal component analysis (PCA) plot of samples colored by different groups illustrating a separation of the samples based on the first principal components; volcano plots illustrating the log₂ protein ratios comparing (C) wild-type versus gp130^Y757F mice with early GC; (D) wild-type versus gp130^Y757F mice with late GC; (E) gp130^Y757F mice (early versus late GC); (F) wild-type mice (early versus late). Proteins were deemed differentially regulated if the log2 fold change in protein expression was ≥1-fold and exhibited an adjusted p-value ≤ 0.05.

Figure 2

Heatmaps displaying the log intensities of the most differentially expressed proteins across the pairwise comparisons. (A) Wild-type versus gp130^Y757F mice with late GC; (B) wild-type (early versus late); (C) wild-type (early) versus gp130^Y757F mice with early GC; (D) gp130^Y757F mice (early versus late GC).

Figure 3

Therapeutic inhibition of IL-11 signaling. (A) gp130^Y757F mice with established gastric tumors were treated with an isotype control (black), or anti-IL11R antibody (blue), or IL-11 Mutein-PEG (red) for 4 consecutive weeks. (B) Total gastric tumor number and mass for the treatment group is indicated. Horizontal lines indicate the mean. **** p < 0.0001, *** p < 0.001, ** p < 0.01 Student’s t-test. (C) Representative whole mounts of stomachs from each treatment group. Scale bar = 6mm. Dotted lines outline regions of macroscopic tumor. (D) Relative gene expression for isolated gastric epithelial cells from each treatment group presented +/− SEM. **** p < 0.0001, *** p < 0.001, ** p < 0.01 Student’s t-test.

Figure 4

Serum biomarkers following therapeutic inhibition of IL-11 signaling. (A) Principal component analysis (PCA) plot of samples colored by different groups illustrating a separation of the samples based on the first principal components. Volcano plots illustrating the log2 protein ratios comparing pre-treatment versus end of treatment between (B) control-treated mice and anti-IL-11R mAb-treated mice and (C) IL-11 Mutein-treated mice and (D) pre-treatment versus mid-treatment IL-11 Mutein-treated mice. Proteins were deemed differentially regulated when the log2 fold change in protein expression was ≥1-fold and exhibited an adjusted p-value ≤ 0.05. Heatmaps displaying the log intensities of the most differentially expressed proteins across the pairwise comparisons, including pre-treatment versus end of treatment between (E) control-treated mice and anti-IL-11R mAb-treated mice and (F) Mutein-treated mice.

Figure 5

Summary of the serum proteome changes observed during IGC progression and tumor regression.