The thyroid hormone–inactivating (TH-inactivating) enzyme type 3 iodothyronine deiodinase (D3) is an oncofetal protein that is rarely expressed in adult life but has been shown to be reactivated in the context of proliferation and neoplasms. D3 terminates TH action within the tumor microenvironment, thereby enhancing cancer cell proliferation. However, the pathological role of D3 and the contribution of TH metabolism in cancer have yet to be fully explored. Here, we describe a reciprocal regulation between TH action and the cancer-associated microRNA-21 (miR21) in basal cell carcinoma (BCC) skin tumors. We found that, besides being negatively regulated by TH at the transcriptional level, miR21 attenuates the TH signal by increasing D3 levels. The ability of miR21 to positively regulate D3 was mediated by the tumor suppressor gene
Daniela Di Girolamo, Raffaele Ambrosio, Maria A. De Stefano, Giuseppina Mancino, Tommaso Porcelli, Cristina Luongo, Emery Di Cicco, Giulia Scalia, Luigi Del Vecchio, Annamaria Colao, Andrzej A. Dlugosz, Caterina Missero, Domenico Salvatore, Monica Dentice
TH represses miR21 in mouse and human BCC.