Human VAT-1: a calcium-regulated activation marker of human epithelial cells.

BACKGROUND AND AIMS: Human VAT-1 (hVAT-1) is a homologue of the synaptic vesicle membrane protein of Torpedo californica. Its coding gene is located near the BRCA1 locus and thus hVAT-1 may be linked to an inherited predisposition to breast and ovary cancer. However, the hVAT-1 protein expression pattern in normal epithelial tissues such as skin, mammary gland and ovary, as well as in tumours of the mammary gland and ovary, has not been studied.

METHODS

To address this issue, an immunohistological analysis of biopsies of normal epidermis and lesional epidermis of bullous pemphigoid and pemphigus vulgaris patients was undertaken.

RESULTS

hVAT-1-expression was observed in basal keratinocytes of lesional epidermis of bullous pemphigoid patients but not in normal epidermis or in lesional epidermis of pemphigus vulgaris patients. Moreover, hVAT-1 expression in HaCaT cells was found to be calcium-dependent. Normal and malignant mammary and ovary epithelium were found to be hVAT-1-negative.

CONCLUSIONS

Our results indicate that hVAT-1 exerts a specific function in keratinocyte physiology, in particular in calcium-regulated processes, with no evident deregulation in malignancies of the breast and ovary.