Sphingosine Kinase 1(SphK1) – A Novel Marker for Cancer Risk Assessment in Oral Premalignancy

Abstract

Introduction

Head and neck cancer is the sixth most common cancer worldwide, resulting in approximately 550,000 diagnoses of new cases and 300,000 deaths per year globally. Overexpression of Sphingosine kinase - 1 (SphK1) is found in head and neck squamous cell carcinoma (HNSCC) from early to advanced stages and is associated with tumor progression, invasion, metastasis and poor prognosis. This study assesses the expression of sphingosine kinase - 1 (SphK1) in oral leukoplakia and oral squamous cell carcinoma (OSCC)  and suggests its role as a potential biomarker tool for cancer risk assessment in oral leukoplakia.

Methods

In this retrospective study, eighty-two (n = 82) archival formalin-fixed paraffin blocks consisting of 10 normal tongue mucosa (Group A), 42 cases of oral leukoplakia (Group B) and 30 cases of OSCCs (Group C) were selected and subjected to immunohistochemical staining for anti-rabbit SphK1 antibody. The three different groups were compared for the presence of Sphk1 expression. The clinicopathological parameters such as age, gender, habits, histopathology, and Sphk1 expression were analyzed and compared between the malignantly transformed leukoplakia with untransformed leukoplakia.

Results

Positive SphK1 expression was found in 18 out of 42 (42.9 %) cases of oral leukoplakia and 17 out of 30 (56.7 %) cases of OSCCs while there was no SphK1 expression in normal tongue mucosa. The expression of SphK1 among three different groups of tissue samples was statistically significant (P = 0.007). The correlation between the malignant transformed and untransformed leukoplakia lesion with respect to SphK1 expression was also found to be statistically significant (P= 0.007)

Conclusions

Positive SphK1 expression in oral leukoplakia is suggestive of an increased risk for malignant transformation which can be used as a biomarker tool. Higher SPHK1 expression in the OSCC may suggest an important role in the early stages of tumorigenesis.