TTF-1

Thyroid transcription factor-1 (TTF-1) is a nuclear transcription factor that mainly exists in thyroid follicular epithelial cells and type II alveolar cells. It participates in normal development and function maintaining of the thyroid and lung by regulating gene coding. Some research found that TTF-1 is expressed in differentiated thyroid cancer, and it is involved in the occurrence and development of tumors. This may be because the mutated TTF-1 loses its regulatory function, causing the cell inability to differentiate normally. Meanwhile, TTF-1 is a crucial biomarker for the differential diagnosis of lung adenocarcinoma, and its high expression is related to tumor metastasis and recurrence. Some scholars believe that TTF-1 can activate proto-oncogene, accelerate cell cycle, and promote tumor angiogenesis. However, the co-expression of TTF-1 and P40, which is used to label lung squamous cell carcinoma, is present in some non-small cell lung cancers, providing a new research direction for the pathogenesis of lung tumors. In addition, TTF-1 can be used for the diagnosis of small cell lung cancer, but its prognostic value is controversial.