Background: Apoptosis appears to play an important role in the pathogenesis of hypertrophic cardiomyopathy (HCM). We have previously reported 3 HCM patients carrying the E334K MYBPC3, and that heterologous expression of E334K cMyBPC in cultured cells induced apoptosis. The purpose of this study was to identify pharmacological agents that would inhibit apoptosis in HL-1 cardiomyocytes expressing E334K cMyBPC.
Methods and results: E334K cMyBPC expression in cells increased levels of pro-apoptosis (p53, Bax and cytochrome c) and decreased levels of anti-apoptosis (Bcl-2 and Bcl-XL). While the beta blocker carvedilol (1 μM) normalized the level of p53 and Bcl-2 and the calcium channel blocker (CCB) bepridil (0.5 μM) normalized that of Bcl-2, both the CCB azelnidipine (1 μM) and the angiotensin receptor blocker (ARB) olmesartan (10 μM) normalized those of p53, Bax, cytochrome c, and Bcl-XL. Among those proteins, cytochrome c was the one which showed the highest degree of change. Both azelnidipine (0.1 μM) and olmesartan (1 μM) reduced the level of cytochrome c by 40.2 ± 4.3% and 31.3 ± 5.1%, respectively. The CCB amlodipine and the ARB valsartan reduced it only by 19.1 ± 2.1% and 20.1 ± 5.2%, respectively. Flow cytometric analysis and annexin V staining showed that treatment of cells with azelnidipine (0.1 μM) plus olmesartan (0.3 μM) or that with amlodipine (0.1 μM) plus valsartan (0.3 μM) reduced the number of apoptotic cells by 35.8 ± 10.5% and 18.4 ± 3.2%, respectively.
Conclusion: Azelnidipine plus olmesartan or amlodipine plus valsartan inhibited apoptosis of HL-1 cells expressing E334K cMyBPC, and the former combination was more effective than the latter.
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