Maspin, novel protease inhibitor with tumor suppressing activity in breast cancer

Maspin (mammary serpin) is a novel serine protease inhibitor related to the serpin family with tumor suppressing function in breast cancer. Maspin was originally identified from normal mammary epithelium by substractive hybridisation and might function as a class II tumor suppressor gene. Maspins decreased expression with increased level of malignancy and its loss in metastatic cells is regulated at the transcriptional level. Transfection of tumor cells with maspin cDNA inhibits invasion and motility and decreases tumor growth and metastatic ability in nude mice. The progressive loss of expression of maspin during tumor progression makes this novel protein an interesting diagnostic and prognostic marker. The reexpression of maspin by pharmacological intervention potentially offers a promising approach as a therapeutic option in breast cancer therapy.