N-4-tert-butyl benzyl haloperidol chloride suppresses Ca2+-dependent Egr-1 expression and subsequently inhibits vascular smooth muscle cell proliferation induced by angiotensin II.

BACKGROUND N-4-Tert-Butyl benzyl haloperidol chloride (C(3)) was a novel calcium antagonist synthesized in our laboratory. The present study is to explore the effect of C(3) on vascular smooth muscle cell proliferation and the mechanism involved. METHODS The effects of C(3) on Ang II-induced cytosolic free Ca(2+) concentration change, VSMC proliferation, the key early growth response factor 1 (Egr-1) were evaluated by laser scanning confocal microscopy, microtiter tetrazolium (MTT) proliferation assay, flow cytometry analysis, Western blot and RT-PCR analysis, respectively. An extracellular Ca(2+) chelator EGTA and antisense Egr-1 oligodeoxyribonucleotides (ODNs) were used to establish the relation between Ca(2+)-dependent Egr-1 expression induced by Ang II and VSMC proliferation. RESULTS C(3) attenuated the Ang II-induced extracellular Ca(2+) influx, inhibited VSMCs proliferation and arrested VSMCs in G(1)-phase. C(3) also triggered a significant reduction in PDGF-A and cyclin D1, Cdk2 along with an overexpression of p21Cip1. Antisense Egr-1 ODNs inhibited VSMCs proliferation, which was related to G(1)-phase arrest, due to inhibiting the expression of Egr-1 and C(3) inhibited the overexpression of Egr-1. CONCLUSION Egr-1 may play a key role in Ang II-induced proliferation of VSMCs. C(3) inhibits vascular smooth muscle cell proliferation and the mechanism is involved with the inhibition of over-expression of Egr-1.