Stromal Fibroblasts Mediate Extracellular Matrix Remodeling and Invasion of Scirrhous Gastric Carcinoma Cells

Abstract

Scirrhous gastric carcinoma (SGC) has the worst prognosis of all gastric cancers, owing to its rapid expansion by invasion and frequent peritoneal dissemination. Due to the increased proliferation of stromal fibroblasts (SFs) that occurs within SGC lesions and the peritoneal metastatic sites, SFs have been proposed to support the progression of this disease. However, the biological and molecular basis and the pathological role of the intercellular interaction between SGC cells and SFs remain largely unknown. In this study, we investigated the role of SFs in the invasion of the extracellular matrix (ECM) by SGC cells. When SGC cells were cocultured with SFs derived from SGC tissue on three-dimensional (3D) Matrigel, they were attracted together to form large cellular aggregates that invaded within the Matrigel. Time-lapse imaging revealed that this process was associated with extensive contraction and remodeling of the ECM. Immunofluorescence and biochemical analysis showed that SGC cells stimulate phosphorylation of myosin light chain and actomyosin-mediated mechanical remodeling of the ECM by SFs. By utilizing this assay system for inhibitor library screening, we have identified several inhibitors that potently suppress the cooperation between SGC cells and SFs to form the invasive structures. Among them, a Src inhibitor dasatinib impaired the interaction between SGC cells and SFs both in vitro and in vivo and effectively blocked peritoneal dissemination of SGC cells. These results indicate that SFs mediate mechanical remodeling of the ECM by SGC cells, thereby promoting invasion and peritoneal dissemination of SGC.

A high number of IgG4-positive cells in gastric cancer tissue is associated with tumor progression and poor prognosis

“…These cancers, especially Borrmann 4 gastric cancers, are characterized by rapid cancer cell infiltration and proliferation, accompanied by extensive stromal fibrosis. Increased proliferation of stromal fibroblasts within scirrhous gastric carcinoma lesions and peritoneal metastatic sites suggests that stromal fibroblasts support the progression of this disease [43]. IgG4-RD is also characterized by a variable degree of fibrosis [22][23][24].…”

Microvesicles released from tumor cells disrupt epithelial cell morphology and contractility

“…Our results provide new insights into how tumor cell-shed MVs can influence the microenvironment by promoting ECM reorganization. Specifically, we showed that MVs from cancer cells increased epithelial cell contractility, which is known to be required for ECM remodeling and reorganization (Alcoser et al, 2014; Yamaguchi et al, 2014). Interestingly, tumor shed MVs can also mediate the transformation of fibroblasts into cancer associated fibroblasts (Webber et al, 2010).…”

Cancer-associated fibroblasts modulate growth factor signaling and extracellular matrix remodeling to regulate tumor metastasis

“…In contrast, tumors in WT mice consisted of radially aligned collagen fibers with interacting tumor cells along them, suggesting a more invasive tumor microenvironment [37]. Mechanical remodeling of the ECM through increased contractility of CAFs was also observed in scirrhous gastric carcinoma (SGC) [38]. Co-culture of SGC cells and CAFs generated ‘invasive foci’ in Matrigel.…”

“…These invasive foci were comprised of CAFs, which reorganized the matrix through actin–myosin contractility, and cancer cells that surrounded the CAFs invaded into Matrigel. Interestingly, treatment with the myosin-II (MyoII) inhibitor blebbistatin significantly reduced the invasion of these foci, whereas treatment with the broad MMP inhibitor GM6001 did not perturb the matrix remodeling and invasion phenotype [38]. …”