A role of novel serpin maspin in tumor progression: the divergence revealed through efforts to converge.
Maspin, a 42 kDa protein, belongs to the serine protease inhibitor (serpin) superfamily and is more closely related to the ovalbumin-like serpin subfamily (ov-serpins). More than a decade after the discovery of the maspin gene, our pursuit of the molecular mechanisms of maspin revealed a significant divergence of maspin from other serpins. This review article summarizes recent advances in the identification of maspin-binding proteins and the potential underlying molecular mechanisms of maspin in tumor progression. Specifically, the molecular interactions of maspin with the cell surface-associated pro-urokinase-type plasminogen activator (pro-uPA) and intracellular histone deacetylase 1 (HDAC1) are highlighted. Our new evidence suggests a new paradigm that maspin acts as a serpin-like molecule to inhibit serine protease-like targets. From an evolution point of view, the uniquely important function of maspin in development and tumor progression is likely due to its ancestral sequence code, and accordingly, its novel "meta"-serpin structure. It is reasonable to hypothesize that the conservation of a serine protease-like catalytic center in many molecules requires the co-existence of endogenous antagonists. The unique inhibitory interaction of maspin with both HDAC1 and pro-uPA might not be substituted by other serpins that have evolved to acquire higher target specificities. Thus, tumor suppressive maspin offers a unique therapeutic opportunity.
Sheng
Shijie
S
Department of Pathology, The Proteases and Cancer Program of the Karmanos Cancer Institute, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA. ssheng@med.wayne.edu
D018450:Disease Progression; D005786:Gene Expression Regulation; D016147:Genes, Tumor Suppressor; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D009369:Neoplasms / Q000378:metabolism / Q000473:pathology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D015843:Serpins / Q000235:genetics / Q000378:metabolism*; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism
C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; C085344:SERPIN-B5; D015843:Serpins; D014568:Urokinase-Type Plasminogen Activator; C110550:HDAC1 protein, human; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases