FOXO1 Expression and Its Prognostic Significance in Oral Squamous Cell Carcinoma: An Immunohistochemical Study

Abstract Background OSCC is the most common and aggressive malignancy of the oral cavity. OSCC has unfavorable prognosis, a high rate of recurrence and a low rate of survival. The fork head box protein O1 (FOXO1) is a transcription factor involved in processes such as apoptosis, oxidative stress and cancer suppression, but its prognostic value for OSCC is not fully understood. Aim The present study aimed to investigate the expression of FOXO1 at various histological grades of OSCC and study its association with apoptosis, proliferation, oxidative stress and clinicopathological features Materials and Methods A total of eighty subjects were included in the study that were divided into four groups such as control (healthy) group, well-differentiated OSCC, moderately differentiated OSCC, poorly differentiated OSCC (n = 20 in each group). The immunohistochemical assessment was performed for FOXO1, Caspase-3, Ki-67, PCNA, and Bcl-2 expression levels. The oxidative stress markers such as MDA and SOD was also measured. Statistically evaluated correlations between FOXO1 expression and clinicopathological features were assessed. Results The expression of FOXO1 was decreased in OSCC tissues compared with controls and reduced significantly with increasing tumor grade (P < 0.001). Downregulated FOXO1 expression was correlated positively with reduced expression of Caspase-3 and SOD levels whereas negatively with expression levels of Ki-67, PCNA, Bcl-2, MDA, inflammation score, size of the tumor, status of the lymph nodes, recurrence and survival. Patients with high expression of FOXO1 had a lower recurrence and better survival rates than patients with low expression of FOXO1. Conclusion Downregulation of FOXO1 is correlated positively with the progression of OSCC, diminished apoptosis, accelerated proliferation, oxidative stress and poor outcome of the OSCC patients. FOXO1 is a reliable prognostic marker and could be the target for therapy for OSCC.