Type IV Collagen in Human Colorectal Liver Metastases—Cellular Origin and a Circulating Biomarker

Abstract

Circulating type IV collagen (cCOL IV) is a potential biomarker for patients with colorectal liver metastases (CLM) who present with elevated levels of COL IV in both CLM tissue and circulation. This study aimed to establish the cellular origin of elevated levels of COL IV and analyze circulating COL IV in CLM patients. The cellular source was established through in situ hybridization, immunohistochemical staining, and morphological evaluation. Cellular expression in vitro was assessed by immunofluorescence. Tissue expression of COL IV-degrading matrix metalloproteinases (MMPs)-2, -7, -9, and -13 was studied with immunohistochemical staining. Plasma levels of COL IV in CLM patients and healthy controls were analyzed with ELISA. This study shows that cancer-associated fibroblasts (CAFs) express COL IV in the stroma of CLM and that COL IV is expressed in vitro by fibroblasts but not by tumor cells. MMP-2, -7, -9, and -13 are expressed in CLM tissue, mainly by hepatocytes and immune cells, and circulating COL IV is significantly elevated in CLM patients compared with healthy controls. Our study shows that stromal cells, not tumor cells, produce COL IV in CLM, and that circulating COL IV is elevated in patients with CLM.

ECM Substrates Impact RNAi Localization at Adherens Junctions of Colon Epithelial Cells

“…In addition, the ECM array results show that when the concentration of collagen IV is higher (125–250 µg/mL; Figure 8 A,B and Figures S1 and S2 ), compared to our individually coated coverslips ( Figure 2 and Figure 3 ; 45 µg/mL), can also negatively impact junctional localization of PLEKHA7 and AGO2, even in combination with laminin ( Figure 8 A,B). Indeed, increased collagen IV levels have been observed and shown to contribute to liver metastasis and fibrosis [ 72 , 73 , 74 , 75 ]. In addition, targeting collagen IV reduced tumor volume in mouse xenografts [ 92 ].…”

“…For example, brush border enzyme activity levels, cell spreading rates, migration rates, and proliferation rates of colon epithelial Caco2 cells change when plated on different ECM substrates, such as laminin, fibronectin, collagen I, and collagen IV [ 71 ]. Importantly, during tumorigenesis, the composition of the colonic mucosa changes considerably and exhibits increased levels of fibronectin and collagen I, compared to normal conditions [ 24 , 28 ], whereas increased collagen IV in metastatic tumors is associated with poor survival [ 72 , 73 , 74 , 75 ]. Although it is well-documented that this switch in the ECM composition and the overall occurrence of fibrotic tissue correlates with colorectal cancer progression, the mechanistic underpinnings of this relationship are still poorly understood.…”

Prognostic circulating proteomic biomarkers in colorectal liver metastases

“…The tumour stroma contains non-cancerous components such as non-malignant cells, blood vessels, and ECM [19] . The enzymatic remodelling of ECM upregulates collagen, and increased collagen deposition promotes tumour proliferation [19] . COL IV is a stromal protein with potential prognostic ability in patients with CRLM [19] .…”

“…The enzymatic remodelling of ECM upregulates collagen, and increased collagen deposition promotes tumour proliferation [19] . COL IV is a stromal protein with potential prognostic ability in patients with CRLM [19] . Lindgren et al [19] used ELISA to compare preoperative plasma COL IV levels in CRLM patients that underwent resection (n = 138) and in a healthy control group (n = 118).…”

“…COL IV is a stromal protein with potential prognostic ability in patients with CRLM [19] . Lindgren et al [19] used ELISA to compare preoperative plasma COL IV levels in CRLM patients that underwent resection (n = 138) and in a healthy control group (n = 118). Preoperative plasma COL IV was elevated in CRLM patients in comparison to controls, especially for those with advanced stage and large metastatic burden (p < 0.01) [19] .…”