SPARCL1 Modulates the Tumor Microenvironment and Suppresses Colorectal Cancer and Liver Metastasis through the CCL20/CCR6 Axis

Abstract

Background and Purpose: To investigate the expression and biological functions of secreted protein acidic and rich in cysteine-like 1 (SPARCL1) in the tumor microenvironment of colorectal cancer liver metastases (CRCLM). More over the study aimed to provide a new molecular marker for targeted therapy. Methods: Thirty male C57BL6/J mice were randomly divided into the control group (n = 3), the CRCLM group (n = 7), the CRCLM+Lv-vector group (n = 5), the CRCLM+Lv-SPARCL1 group (n = 5), the CRCLM+Lv-vector shRNA group (n = 5), and the CRCLM+Lv-SPARCL1 shRNA group (n = 5). Mice liver tissues in each group was obtained. The histopathological changes and indexes were measured by hematoxylin and eosin (H&E) staining, Reverse transcription quantitative PCR (polymerase chain reaction) (RT-qPCR), western blot, Masson staining, Enzyme-linked immunosorbent assay (ELISA), and flow cytometry. Results: SPARCL1 mRNA and protein expression levels in the CRCLM group decreased compared to the control group (p < 0.05). Further SPARCL1 upregulation reduced the metastatic foci number, collagen area (%), expression of collagen I, collagen Ⅲ, α-SMA (sarcomeric actin), CCL20 (chemokine CC-motif ligand 20), CCR6 (CC chemokine receptor 6), N-cadherin, and vimentin, percentage of Th17 cells, and IL (interleukin)-1β, IL-17, and TNF (tumor necrosis factor)-α content (p < 0.05). However, E-cadherin expression and IL-6, IL-8, and IL-10 content increased (p < 0.05). In contrast, downregulating SPARCL1 reversed the above index trends. Conclusions: SPARCL1 effectively reduced liver metastasis, collagen deposition, and liver fibrosis. Furthermore, it activated CCL20/CCR6 axis to inhibit immune responses and epithelial-to-mesenchymal transition (EMT), thus providing an experimental basis for targeted therapy.