Thyroid Cancer and Fibroblasts

SIMPLE SUMMARY: Thyroid cancer is the most common solid tumor of the endocrine glands. The cancer cell contribution to thyroid cancer development and progression has been studied extensively, whereas the involvement of the tumor microenvironment, particularly of cancer-associated fibroblasts (CAFs), in thyroid cancer growth still must be largely analyzed. The tumor microenvironment, comprising molecules, blood and lymphatic tumor vessels and several non cancer stromal cells, such as CAFs, dramatically influences solid tumor growth and therapy resistance. In particular, investigations on CAF contribution to solid tumor growth and therapeutic resistance represent an important area of oncological research. Moreover, studies focused on the role of CAFs in thyroid cancer could lead to a better comprehension of mechanisms regulating cancer growth and to the development of new therapeutic strategies. Therefore, in this paper, we review the hallmarks of CAFs and their role on thyroid cancer. ABSTRACT: Thyroid cancer is the most common type of endocrine cancer, and its prevalence continue to rise. Non-metastatic thyroid cancer patients are successfully treated. However, looking for new therapeutic strategies is of great importance for metastatic thyroid cancers that still lead to death. With respect to this, the tumor microenvironment (TME), which plays a key role in tumor progression, should be considered as a new promising therapeutic target to hamper thyroid cancer progression. Indeed, thyroid tumors consist of cancer cells and a heterogeneous and ever-changing niche, represented by the TME, which contributes to establishing most of the features of cancer cells. The TME consists of extracellular matrix (ECM) molecules, soluble factors, metabolites, blood and lymphatic tumor vessels and several stromal cell types that, by interacting with each other and with tumor cells, affect TME remodeling, cancer growth and progression. Among the thyroid TME components, cancer-associated fibroblasts (CAFs) have gained more attention in the last years. Indeed, recent important evidence showed that thyroid CAFs strongly sustain thyroid cancer growth and progression by producing soluble factors and ECM proteins, which, in turn, deeply affect thyroid cancer cell behavior and aggressiveness. Hence, in this article, we describe the thyroid TME, focusing on the desmoplastic stromal reaction, which is a powerful indicator of thyroid cancer progression and an invasive growth pattern. In addition, we discuss the origins and features of the thyroid CAFs, their influence on thyroid cancer growth and progression, their role in remodeling the ECM and their immune-modulating functions. We finally debate therapeutic perspectives targeting CAFs.