Expression patterns of L-plastin isoform in normal and carcinomatous breast tissues

Plastins are members of a family of actin-binding proteins which exhibit a tissue-specific expression pattern. L-plastin, which is specifically expres sed in hematopoietic cell lineage, has been proposed to be involved in the control of cell adhesion and motility. This protein is also frequently expr essed in cell lines derived fi om mammary solid tumors and therefore might be involved in cancer invasion and metastasis. We have analysed plastin exp ression in normal and carcinomatous breast tissues in vivo by immunohistoch emistry and immunoblotting approaches using specific plastin isoform antibo dies. L-plastin was not detected in normal epithelial cells of the mammary gland whereas a staining of myoepithelial cells was observed in 50% of the cases. In breast carcinomas, a significant immunostaining of malignant epit helial cells was observed in 4 of the 29 cases analysed (13.8%). No concent ration between L-plastin expression and tumor size, histological grade or l ymph node status was observed In contrast, L-plastin was found expressed in 4 of the 11 estrogen and progesterone receptors negative tumors (p = 0.039 ). The potential role of plastin expression in the tumor process is discuss ed.