Effect Of Diltiazem On The Expression Of Proto-oncogene In Proliferated Vascular Smooth Muscle Cells

Myocardial infarction, cerebrovascular accident, and other cardiovascular and cerebrovascular diseases are the elderly multiple common diseases, mainly due to atherosclerosis (AS). Experimental studies confirmed that a large number of VSMC proliferation play an important role in the pathophysiology of AS. Proto-oncogene c-myc, c-fos, c-jun and ras activation and abnormal expression are not only the inherent basis, but also an important link of VSMC proliferation, which play an important role in the various stages of that proliferation, stagnation, the process of differentiation and death of VSMC.CCB is one of the commonly used drugs in the clinical treatment of cardiovascular diseases. And lots of experiments have confirmed CCB can inhibit the proliferation of VSMC, but the researches have been concentrating in that dihydropyridine (DHPs, nifedipine, etc.), Phenylalky- lamines (PAAs, verapamil, etc.) which can affect the expression of proto-oncogenes to inhibit VSMC proliferation and prevent AS. However, the studies on Benzothiazepines (BTZs, Diltiazem (Diltiazem, Dil, etc.) effecting proto-oncogene expression to inhibit VSMC proliferation and prevent AS have not yet been reported.OBJECTIVETo investigate the effect of Dil on VSMC proliferation and the expression of the proto-oncogene c-myc, c-fos, c-jun and ras mRNA. To discuss the effect of Dil inhibiting VSMC proliferation and its mechanisms.METHODSInitially, VSMC were cultured by tissue-sticking method. In order to make model, 10-7mol/L Angâ…¡was used to induce VSMC to proliferate. Then they were randomly divided into 5 groups: control group, model group, Dil groups (Dil divided into 10-5, 10-6 and 10-7mol/L). Finally, the cell proliferation ability was measured by MTT assay, the cell generation cycle and prolifation index were measured by Flow cytometery, and the expressions of c-myc,c-fos and c-jun and ras mRNA were examined by rt-PCR.Results(1) Compared with control group, OD value of model group obviously increased (P<0.05), the percentage of G0/G1 period obviously decreased (P<0.05), S period, G2/M period and proliferation index of it significantly increased (P<0.05), what proved that Angâ…¡could promote the proliferation of VSMC.(2) Compared with model group: in all Dil groups, OD values obviously decreased, the percentage of G0/G1 period significantly increased (P<0.05), and S period and proliferation index obviously decreased (P<0.05), what proved that Dil inhibited the proliferation of VSMC induced by Angâ…¡, and effect size and concentration positively correlated. The mRNA expressions of c-myc, c-fos and c-jun in Dil high and middle dosage groups were obviously decreased (P<0.05), and the mRNA expressions of ras were significantly increased (P<0.05), what proved that Dil down-regulated the mRNA expressions of c-myc, c-fos and c-jun and up-regulated the mRNA expressions of ras, and effect size correlated with concentration positively.ConclusionsDil inhibited the proliferation of VSMC induced by Angâ…¡, and effect size and concentration positively correlated. The mechanism concerned with down- regulating the expression of c-myc, c-fos and c-jun and up-regulating the expression of ras.