Prss27, also known as pancreasin and marapsin, is a serine protease preferentially expressed by stratified squamous epithelia [3]. It belongs to the family of type I serine proteases, and in some cases, is inserted into plasma membranes via glycosylphosphatidylinositol (GPI) anchors [3,4]. However, its exact physiological function and associated pathways are still being explored, and genetic models such as mouse models can help in understanding its role.

In esophageal squamous cell carcinoma (ESCC) patients who received preoperative treatment, Prss27 expression in resected tumor samples was a predictor of poor prognosis. Also, conversion of Prss27 expression from positive in biopsy samples to negative in resected tumor samples predicted good prognosis, suggesting it could be an effective tool for adjuvant treatment decision-making in ESCC patients [1].

In a study on children with overweight/obesity, although the differences disappeared after FDR correction, PRSS27 was among the proteins differentially expressed between fit and unfit children, potentially being involved in biological processes like immune/inflammatory response, neurogenesis, signal transduction, and platelet activation [2].

A pan-cancer study indicated that PRSS27 has prognostic significance in breast cancer and other cancers' survival, and in vitro experiments confirmed it as an oncogene in breast cancer [5].

Prss27-null mice develop normally in barrier conditions and are fertile without overt epithelial defects, indicating that marapsin (Prss27) does not play critical, non-redundant roles in development, reproduction, or epithelial differentiation [3].

In conclusion, Prss27, as a serine protease, seems to play a role in cancer prognosis, especially in ESCC and breast cancer, and might be involved in some biological processes related to fitness in children with overweight/obesity. The Prss27-null mouse model has shown that it is not essential for basic development, reproduction, or epithelial differentiation, providing insights into its non-critical roles in these aspects. These findings contribute to understanding the biological functions of Prss27 and its potential as a prognostic biomarker and therapeutic target in cancer research.