Introduction: Aquaporins (AQPs) are a large family of water channel proteins  that facilitate transepithelial water movement across the cell membrane. In humans, 13 isoforms (AQP0 to AQP12) have been identified of which, AQP3 has been detected to be expressed in many epithelial cells of various organs. The overexpression of AQP3 has been observed in several cancers including oral cancer, where it contributes to metastasis and proliferation. The expression is related to tumor grade, with an increase expression in tumour areas than in non tumor areas.

Objectives: To evaluate Aquaporin-3 (AQP3) expression in patient samples of normal oral mucosa, oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC), thereby assessing the potential of AQP3 as a molecular marker for tumour progression.

Study Design: An in vitro comparative study was done to determine the AQP3 expression on 20 surgical biopsy specimens each of normal oral mucosa, OED and OSCC, using immunohistochemistry. The results were statistically analysed using one-way analysis of variance (ANOVA) and post hoc analysis.

Results: The expression of AQP3 was analysed and further semi quantified with H-score. The mean H-score showed a statistically significant difference between OSCC, OED and normal oral mucosa. There was a significant increase in the expression of AQP3 in OSCC and OED when compared to normal oral mucosa. The highest expression was observed in OSCC.

Conclusion: The observations of the study signify that staining intensity of AQP3 increased from dysplastic non-invasive lesion to invasive OSCC, suggesting a possible role of AQP3 as a biomarker for tumour progression.

Keywords:  Aquaporin, Oral carcinoma, Biomarker, Oral potentially malignant disorders