Prognostic significance of the FSTL1-DIP2A axis in early-stage tongue cancer.

In tongue cancer, many patients already have metastasis at the time of diagnosis, and such cases are usually unresponsive to treatment, resulting in a poor prognosis. Therefore, there is an urgent need to develop more effective diagnostic and therapeutic methods to cure tongue cancer at the earliest possible stage in clinical practice. Follistatin-like 1 (FSTL1) is known as a negative effector molecule that induces and enhances the refractoriness of cancer cells directly and indirectly via suppressing anti-tumor immunity in various types of cancer. However, the molecular expression, functions, and clinical significance of FSTL1 and its receptor DIP2A in tongue cancer remains to be elucidated. In this study, we revealed that FSTL1, which is highly expressed in tongue cancer cells, plays a key role in its malignancy and is a significant risk factor for recurrence of early-stage tongue cancer. Basic study shows that FSTL1 is abundantly produced from human tongue cancer cell lines, and blocking FSTL1 with specific siRNAs or mAb significantly suppresses cellular functions. Clinical study shows that both FSTL1 and its receptor DIP2A are highly and correlatively expressed in tumor tissues of tongue cancer patients, and high expression levels of both in stage I tumors are significantly associated with shorter relapse-free survival. These suggest that targeting the FSTL1-DIP2A axis may be useful as a biomarker for early prediction of prognosis in tongue cancer patients, and as a therapeutic target for developing new drugs to treat tongue cancer more effectively. This strategy will contribute to improving clinical outcomes in tongue cancer.