Objective To systematically characterizes the temporal changes in urokinase-type plasminogen activator (uPA) over the course of neoplastic progression using a mouse oral squamous cell carcinoma (OSCC) model induced by 4-nitroquinoline-1-oxide (4-NQO).

Methods A total of 65 wild-type C57BL/6 mice of 5 weeks old were randomly assigned to two groups, a 4-NQO group (n = 50), which received daily administration of 100 μg/mL 4-NQO in drinking water, and a control group (n = 15), which received sterile water. At 12, 16, 20, 22, and 24 weeks, 10 mice from the 4-NQO group and 3 from the control group were randomly selected, weighed, and sacrificed. Tongue tissues were collected for hematoxylin-eosin (HE) staining to preliminarily assess OSCC development, and for immunofluorescence staining and quantitative real-time PCR to evaluate dynamic uPA expression in tongue tissues during OSCC progression.

Results After 16 weeks of exposure, 4-NQO-treated mice exhibited significantly lower body mass compared with that of the controls (P < 0.05) and the weight loss became increasingly more pronounced over time. Histopathological changes in tongue tissues progressed in a clearly time-dependent manner—hyperplasia and mild dysplasia emerged at week 12, while moderate-to-severe dysplasia and carcinoma were observed by week 22, yielding a tumorigenic rate of 25%, which escalated to 70% by week 24. Immunofluorescence and qPCR analyses demonstrated a pronounced, progressive up-regulation of uPA expression in lesional tissues as OSCC progressed (P < 0.0001).

Conclusion This study not only confirmed the uniqueness of the 4-NQO model in OSCC research, but also revealed the changes in uPA during tumor invasion. These findings provide a theoretical foundation for the development of early diagnosis and precision treatment strategies, holding significant potential clinical value and research importance for improving patient prognosis.