Expression patterns of aquaporin 1 in vascular tumours.

Background: Aquaporins (AQPs) are a family of water channels expressed in various body tissues. Beyond osmotic balance, AQPs have recently been confirmed to be involved in processes related to cancer (tumour proliferation, angiogenesis, etc.).

Objectives: To analyse the presence of these proteins in the endothelium of several vascular tumours, both benign and malignant, in order to establish whether AQPs may be used as a marker or future therapeutic target.

Materials And Methods: We studied AQP1 expression in 39 patients with vascular tumours, classified into six groups according to ISSVA classification: haemangiomas, benign vascular tumours different from infantile haemangiomas, angiosarcomas, classic Kaposi's sarcoma (KS), and epidemic KS.

Results: AQP1 expression was present in 28 of 39 patients, representing 92.9% benign lesions, whereas no expression was found in 72% of malignant lesions. AQP1 expression was associated with benign lesions with an OR of 34.5 (95% CI: 5-250); p<0.0005, and was most frequently identified with a focal endothelial pattern (38%). A kappa index of 0.823 (95% CI: 0.678-0.971) was determined regarding the patterns of expression overall.

Conclusion: The expression of AQP1 was greater in benign lesions than malignant lesions and this difference was statistically significant, thus AQP1 expression could serve as a marker for benignity of vascular tumours. In addition, the expression pattern of AQP1 was different according to the type of vascular tumour.