Identification of Two Distinct Carcinoma-Associated Fibroblast Subtypes with Differential Tumor-Promoting Abilities in Oral Squamous Cell Carcinoma

Abstract

Heterogeneity of carcinoma-associated fibroblasts (CAF) has long been recognized, but the functional significance remains poorly understood. Here, we report the distinction of two CAF subtypes in oral squamous cell carcinoma (OSCC) that have differential tumor-promoting capability, one with a transcriptome and secretome closer to normal fibroblasts (CAF-N) and the other with a more divergent expression pattern (CAF-D). Both subtypes supported higher tumor incidence in nonobese diabetic/severe combined immunodeficient (NOD/SCID) Ilγ2(null) mice and deeper invasion of malignant keratinocytes than normal or dysplasia-associated fibroblasts, but CAF-N was more efficient than CAF-D in enhancing tumor incidence. CAF-N included more intrinsically motile fibroblasts maintained by high autocrine production of hyaluronan. Inhibiting CAF-N migration by blocking hyaluronan synthesis or chain elongation impaired invasion of adjacent OSCC cells, pinpointing fibroblast motility as an essential mechanism in this process. In contrast, CAF-D harbored fewer motile fibroblasts but synthesized higher TGF-β1 levels. TGF-β1 did not stimulate CAF-D migration but enhanced invasion and expression of epithelial–mesenchymal transition (EMT) markers in malignant keratinocytes. Inhibiting TGF-β1 in three-dimensional cultures containing CAF-D impaired keratinocyte invasion, suggesting TGF-β1–induced EMT mediates CAF-D–induced carcinoma cell invasion. TGF-β1–pretreated normal fibroblasts also induced invasive properties in transformed oral keratinocytes, indicating that TGF-β1–synthesizing fibroblasts, as well as hyaluronan-synthesizing fibroblasts, are critical for carcinoma invasion. Taken together, these results discern two subtypes of CAF that promote OSCC cell invasion via different mechanisms. Cancer Res; 73(13); 3888–901. ©2013 AACR.

Co-culture of 3D tumor spheroids with fibroblasts as a model for epithelial–mesenchymal transition in vitro

“…In tumors, stimulated fibroblasts acquire an active phenotype as CAFs, and activated fibroblasts can contribute to EMT through the secretion of TGFβ [18]. In our co-culture system, normal non-CAF fibroblasts introduced showed the characteristics of active CAFs, including morphologic changes and increased α-SMA expression, when cultured in FBS-containing media (Fig.…”

Tumor-derived TGF-β and prostaglandin E2 attenuate anti-tumor immune responses in head and neck squamous cell carcinoma treated with EGFR inhibitor

“…TGF-β can regulate both the innate and acquired immune systems by inducing regulatory CD4+/FoxP3+ T cells, which represent on of the main barriers to antigen-specific antitumor immunity, and by skewing NK T cells or macrophages to regulatory phenotypes [3,4,26]. TGF-β functions not only as an immune regulator, but also as an oncogenesis promoter by inducing epithelial-to-mesenchymal transition through both Smad-dependent and independent pathways [27] or transitioning constitutive cells to a tumor-associated phenotype that facilitates tumor progression [28]. The present study revealed that TGF-β production or reduction by EGFR inhibition is depended on individual tumors.…”

Hyaluronan and RHAMM in Wound Repair and the “Cancerization” of Stromal Tissues

“…The increased expression of extracellular HA binding proteins such as versican has also been reported [152]. Analyses of head and neck tumors reveal previously unappreciated stromal cancer associated fibroblast heterogeneity involving HA: a subpopulation of cancer associated fibroblasts produces high levels of HA and promotes local tissue invasion by cancer cells [153]. …”