Direct in vivo inhibition of the nuclear cell cycle cascade in experimental mesangial proliferative glomerulonephritis with Roscovitine, a novel cyclin-dependent kinase antagonist

Glomerular injury is characterized by mesangial cell (MC) proliferation and matrix formation. We sought to determine if reducing the activity of cyclin-dependent kinase 2 (CDK2) with the purine analogue, Roscovitine, decreased MC proliferation in vitro and in vivo, Roscovitine (25 mu M) inhibited FCS-induced proliferation (P < 0.0001) in cultured MC, Rats with experimental mesangial proliferative glomerulonephritis (Thy1 model) were divided into two groups, A prevention group received daily intraperitoneal injections of Roscovitine in DR ISO (2.8 mg/kg) starting at day 1. A treatment group received daily Roscovitine starting at day 3, when MC proliferation was established, Control Thy1 rats received DMSO alone. MC proliferation (PCNA+/OX7+ double immunostaining) was reduced by > 50% at days 5 and 10 in the Roscovitine prevention group, and at day 5 in the treatment group (P < 0.0001). Early administration of Roscovitine reduced immunostaining for collagen type IV, laminin, and fibronectin at days 5 and 10 (r = 0.984; P < 0.001), which was associated with improved renal function (urinary protein/creatinine, blood urea nitrogen, P < 0.05). We conclude that reducing the activity of CDK2 with Roscovitine in experimental glomerulonephritis decreases cell proliferation and matrix production, resulting in improved renal function, and may be a useful therapeutic intervention in disease characterized by proliferation.