Prss16, also known as Thymus-specific serine protease (TSSP), is a serine protease exclusively expressed in cortical thymic epithelial cells (cTEC) of the thymus. It is thought to be involved in the processing of peptide antigens during the positive selection of T cells and is encoded near the class I major histocompatibility complex (MHC), which has been linked to type 1 diabetes mellitus susceptibility [1,2].

Genetic models, such as the Prss16-knockout (KO) mice, have been used to study its function. Prss16-deficient mice develop normally, with normal thymic morphology, cellularity, and anatomy. The total numbers and frequencies of thymocytes and splenic T-cell populations, as well as surface expression of MHC class II on cTEC, are similar to wild-type controls, suggesting that Prss16 is not required for quantitatively normal T-cell development [1]. However, mice genetically deficient for TSSP are highly prone to spontaneous cancer development, and the absence of TSSP increases the rate of induced colitis-associated colorectal (CAC) tumor formation. This indicates that Prss16 is crucial for the antitumoral role of CD4+ T cells [3].

In conclusion, Prss16 plays a significant role in the thymic development and maturation of CD4+ T cells, which is crucial for antitumoral immune surveillance. The use of Prss16 KO mouse models has revealed its importance in the context of cancer development, contributing to our understanding of the underlying mechanisms and potentially providing insights for cancer prevention and treatment strategies.