Rhabdomyosarcoma Cells Produce Their Own Extracellular Matrix With Minimal Involvement of Cancer-Associated Fibroblasts: A Preliminary Study

Abstract

BackgroundThe interplay between neoplastic cells and surrounding extracellular matrix (ECM) is one of the determinant elements for cancer growth. The remodeling of the ECM by cancer-associated fibroblasts (CAFs) shapes tumor microenvironment by depositing and digesting ECM proteins, hence promoting tumor growth and invasion. While for epithelial tumors CAFs are well characterized, little is known about the stroma composition of mesenchymal cancers, such as in rhabdomyosarcoma (RMS), the most common soft tissue sarcoma during childhood and adolescence. The aim of this work is to identify the importance of CAFs in specifying RMS microenvironment and the role of these stromal cells in RMS growth.MethodsWe assessed in two dimensional (2D) and three dimensional (3D) systems the attraction between RMS cells and fibroblasts using epithelial colon cancer cell line as control. CAFs were studied in a xenogeneic mouse model of both tumor types and characterized in terms of fibroblast activation protein (FAP), mouse PDGFR expression, metalloproteases activation, and ECM gene and protein expression profiling.ResultsIn 2D model, the rate of interaction between stromal and malignant cells was significantly lower in RMS with respect to colon cancer. Particularly, in 3D system, RMS spheroids tended to dismantle the compact aggregate when grown on the layer of stromal cells. In vivo, despite the well-formed tumor mass, murine CAFs were found in low percentage in RMS xenogeneic samples.ConclusionsOur findings support the evidence that, differently from epithelial cancers, RMS cells are directly involved in their own ECM remodeling, and less dependent on CAFs support for cancer cell growth.

DWI and IVIM Imaging in a Murine Model of Rhabdomyosarcoma: Correlations with Quantitative Histopathologic Features

“…Patients with collagen-rich stroma tumors are typically at higher risk of metastasis and this combination creates barriers to systemic radiotherapy and chemotherapy by promoting tumor invasion. 31 Our study showed that ADC and D values were significantly correlated with stromal fraction in a mouse model of RMS. The tumor stroma produced abundant collagen fibers, which could be a major barrier to water molecule diffusion.…”

“…The mechanism of tumor–stroma interaction is of therapeutic importance. Patients with collagen‐rich stroma tumors are typically at higher risk of metastasis and this combination creates barriers to systemic radiotherapy and chemotherapy by promoting tumor invasion 31 . Our study showed that ADC and D values were significantly correlated with stromal fraction in a mouse model of RMS.…”

Context Matters: Response Heterogeneity to Collagen-Targeting Approaches in Desmoplastic Cancers

“…In STS, the cell types responsible for aberrant ECM deposition have not been conclusively identified, but studies of subtypes such as undifferentiated pleomorphic sarcoma and rhabdomyosarcoma suggest that sarcoma cells themselves may be culpable [49,52]. This phenomenon has been more extensively studied in epithelial tumors, where, unlike in sarcomas, cancer-associated fibroblasts (CAFs) have been implicated as the primary source of matrix proteins in the TME.…”

A rhabdomyosarcoma hydrogel model to unveil cell-extracellular matrix interactions

“…GFP + RH30 were kindly provided by Dr Rampazzo. 26 Integrin alpha 5-negative RH30 cells (ITGA5 − RH30) were obtained using ITGA5 siRNA (Santa Cruz Biotechnology, Dallas, Texas, USA) and Mirus TransIT-X2 Transfection Reagent (Mirus Bio, Wisconsin, USA) following the manufacturer's instructions. As a control a siRNA scramble sequence (siNEG, Santa Cruz Biotechnology, Dallas, Texas, USA) was used.…”

“…Trans-wells with coating solution were kept in the incubator for 1 hour) as described elsewhere. 26 Briefly, 1 × 10 5 cancer cells were seeded in the upper chamber, and the lower chamber was filled with serumfree medium. After 24 h, membranes were fixed in 4% PFA and stained with 1 : 10 000 Hoechst solution (Life Technologies, Carlsbad, California, USA) for 15 minutes.…”