Plasma Inter-Alpha-Trypsin Inhibitor Heavy Chains H3 and H4 Serve as Novel Diagnostic Biomarkers in Human Colorectal Cancer.

Objective. Inter-alpha-trypsin inhibitor heavy chain H3 (ITIH3) and inter-alpha-trypsin inhibitor heavy chain H4 (ITIH4) are heavy chains of protein members belonging to the ITI family, which was associated with inflammation and carcinogenesis. However, the diagnostic value of ITIH3 and ITIH4 in human colorectal cancer (CRC) remains unknown. Methods. In total, 101 CRC patients and 156 healthy controls were enrolled. The concentrations of ITIH3 and ITIH4 proteins in plasma samples of participants were assessed using enzyme-linked immunosorbent assay. ITIH3 and ITIH4 expressions in human CRC tissues were additionally assessed via immunohistochemical staining (IHC). Receiver operating characteristic (ROC) was applied to estimate the diagnostic power of the two proteins, and the net reclassification improvement (NRI) was adopted to evaluate the incremental predictive ability of ITIH3/ITIH4 when added to the tissue inhibitor of metalloproteinase-1 (TIMP-1). Results. The plasma concentration of ITIH3 in CRC patients (median: 4.370 mu g/mL; range: 2.152-8.170 mu g/mL) was significantly lower than that in healthy subjects (median: 4.715 mu g/mL; range: 2.665-10.257 mu g/mL; p < 0.001), while the ITIH4 plasma level in subjects with CRC (median: 0.211 mu g/mL; range: 0.099-0.592 mu g/mL) was markedly increased relative to that in the control group (median: 0.134 mu g/mL; range: 0.094-0.460 mu g/mL, p < 0.001). Consistently, IHC score assessment showed a dramatic reduction in ITIH3 expression and, conversely, upregulation of ITIH4 in colorectal carcinoma specimens relative to adjacent normal colorectal tissues (p < 0.001 in both cases). The area under the curve (AUC) of the ROC for ITIH4 (AUC = 0.801, 95% CI: 0.745-0.857) was higher than that for ITIH3 (AUC = 0.638, 95% CI: 0.571-0.704, both p values < 0.001). The AUC of the ROC for combined ITIH3 and ITIH4 was even higher than that for carcinoembryonic antigen. NRI results showed that combining ITIH3 and ITIH4 with TIMP-1 significantly improved diagnostic accuracy (NRI = 17.12%, p = 0.002) for CRC patients compared to TIMP-1 alone. Conclusions. Circulating ITIH3 and ITIH4 levels are associated with carcinogenesis in CRC, supporting their potential diagnostic utility as surrogate biomarkers for colorectal cancer detection.