Porcupine expression promotes the progression of oral carcinogenesis.

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer, which is usually preceded by a potentially malignant disorder histologically diagnosed as dysplasia. We and others have provided evidence for the pro-carcinogenic role of the Wnt/β-catenin pathway in this context, in which Wnt ligands stabilize and allow relocalization of β-catenin to the nucleus for transcription of pro-survival and pro-proliferation genes. However, the contribution of Porcupine (PORCN), an O-acyltransferase that catalyzes the palmitoylation of Wnt ligands, to OSCC carcinogenesis is not known. Moreover, the effectiveness of LGK974, a novel PORCN inhibitor remains to be elucidated. By using different ex vivo, in vivo and in vitro OSCC carcinogenesis models, we show that PORCN expression is significantly increased in high-grade dysplasia as well as moderately/poorly- differentiated OSCC. Consistent with these observations, expression of key proteins involved in the Wnt/β-catenin pathway are elevated as well. Importantly, the treatment with LGK974, a chemical PORCN inhibitor, reduced the number and size of oral lesions in mice treated with 4-Nitroquinoline 1-oxide (4NQO), a tobacco smoke surrogate. These results highlight the role of PORCN during OSCC carcinogenesis.