Ratiometric TGF-β–MMP Biomarkers Capture Pathway Imbalance and Stratify Colorectal Cancer Progression

Introduction: Colorectal cancer (CRC) remains a leading cause of cancer-related mortality worldwide, highlighting the need for biomarkers that improve disease stratification. The transforming growth factor beta (TGF-β) signaling pathway shows stage-dependent effects in CRC, acting as a tumor suppressor in early disease but promoting invasion and metastasis in advanced stages. Matrix metalloproteinases (MMPs) further contribute to extracellular matrix degradation and tumor progression. We hypothesized that ratiometric assessment of TGF-β signaling components relative to MMPs may better capture pathway-level imbalance between regulatory and pro-invasive signaling associated with tumor progression.

Methods: Tissue homogenates from 103 patients undergoing colorectal surgery were analyzed, including benign tissue samples (BTG, n = 29) and colorectal carcinoma samples (MTG, n = 74) stratified by TNM stage. Protein levels of TGF-β1, TGF-β receptor II (TGF-βRII), SMAD4, MMP-7, and MMP-9 were quantified by ELISA. Ratios between TGF-β pathway components and MMPs were calculated and evaluated using receiver operating characteristic (ROC) analysis to assess their discriminatory performance across disease stages.

Results: Several ratiometric markers demonstrated strong discriminatory capacity between benign tissue and CRC stages. The TGF-β1/MMP-7 ratio decreased with advancing tumor stage and demonstrated excellent performance, reaching area under the curve (AUC) values up to 1.00 in specific stage comparisons. A similar stage-related decrease was observed for the TGF-βRII/MMP-9 ratio (AUC, 0.77–0.84). The TGF-βRII/MMP-7 ratio consistently showed high diagnostic performance (AUC, 0.94–0.97), while the TGF-βRII/SMAD4 ratio achieved AUC values of 0.98–1.00 across several stage comparisons.

Conclusions: Ratiometric combinations of TGF-β signaling components and MMPs improve discrimination between benign tissue and CRC stages compared with individual biomarkers. In particular, the TGF-βRII/MMP-7 and TGF-βRII/SMAD4 ratios show strong potential as indicators of CRC progression. These findings support further validation of ratiometric biomarkers and their potential use in multi-marker diagnostic panels and minimally invasive liquid biopsy approaches.