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 play a role in processing peptide antigens during the positive selection of T cells, and is associated with pathways related to T-cell development and immune regulation. The gene is encoded near the class I major histocompatibility complex (MHC) and has been linked to type 1 diabetes mellitus susceptibility [1,2].

Genetic studies using Prss16-deficient mice (a type of KO mouse model) showed that these mice develop normally, are fertile, and have normal thymic morphology, cellularity, and anatomy. The total numbers and frequencies of thymocytes and splenic T-cell populations, as well as the surface expression of MHC class II on cTEC, were 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. Adoptive transfer experiments showed that TSSP-deficient CD4+ T-cell compartment promotes tumor development, associated with high levels of the cytokine IL-17A [3].

In conclusion, while Prss16 may not be essential for normal quantitative T-cell development, it plays a crucial role in antitumoral immunity. The Prss16-KO mouse models have been valuable in revealing its role in tumor suppression, highlighting its importance in understanding the mechanisms behind cancer development and potentially providing new strategies for cancer treatment [3].