Is there a role for survivin in the pathogenesis of PAH?
Survivin belongs to the inhibitor of apoptosis protein (IAP) family, members of which confer protection from death-inducing stimuli (10). One of the most striking features of survivin is its differential expression in cancerous versus normal tissues. Survivin is virtually undetectable in normal adult differentiated tissues but is expressed in most human cancers (11). Thus, dysregulated survivin expression is considered to be a major pathologic mechanism of apoptosis inhibition. However, survivin pathway reactivation may occur in normal cell types, most notably vascular cells, including SMCs and ECs. That SMC survival influences abnormal vessel wall remodeling is supported by data from studies of systemic arteries. Vascular injury increases survivin expression in the vessel wall, concomitantly with neointima formation (12). Similarly, McMurtry and colleagues demonstrate that survivin overexpression coincided with pulmonary vascular remodeling in rats developing monocrotaline-induced PAH
