Forkhead box N1 is possibly a novel biomarker and prognostic indicator for patients with squamous cell lung carcinoma

Background: The roles of Forkhead box N1 (FOXN1) in lung squamous cell carcinoma (LUSC) remains elusive. This study was focused on assessing the expression levels of FOXN1 in LUSC and exploring its potential clinical implications. Methods: Utilizing a range of databases, this study conducted an analysis of the FOXN1 gene's expression levels, comparing LUSC samples with those from normal lung tissues. The expression levels of FOXN1 in primary LUSC and corresponding normal lung tissues were assessed using immunohistochemistry (IHC). Histoscore was used to evaluate the staining degree. χ2 test and Fisher's exact test were employed to assess the association between categorical variables that do not possess an ordinal nature. Multivariate survival analysis was conducted using the Kaplan-Meier method, the Wilcoxon test, and the Cox proportional hazards model. Results: In contrast to normal lung tissues, the expression of the FOXN1 gene was found to be significantly elevated in LUSC tissues (P < 0.01). And FOXN1 was expressed in 79 (98.8%) evaluated LUSC tissues, most of which showed compositive IHC-staining intensity, presenting heterogeneously expression. 69 (87.3%) cases were characterized for strong immunostaining intensity, 70 (87.5%) cases showed moderate intensity, and 66 (82.5%) cases presented weak intensity. Only one sample of normal lung tissue, which represents 10% of the total, exhibited weak immunostaining exclusively (P < 0.05). Additionally, the expression of FOXN1 was found to have a significant correlation with the grading of LUSC, the presence of lymph node and distant metastases, the stage of the disease, and the survival outcomes (P < 0.05). Conclusion: The expression of FOXN1 is frequently increased in LUSC, and the patients with high FOXN1 expression have a poorer survival outcome. FOXN1 can be a novel biomarker and prognostic indicator for LUSC patients.