We sought to determine whether polymorphisms in the large-conductance calcium and voltage-dependent potassium (BK) channel β1 subunit gene, KCNMB1, are associated with blood pressure response to verapamil SR or adverse outcomes in the GENEtic substudy of the INternational VErapamil SR/trandolapril STudy (INVEST-GENES).
KCNMB1 is involved in calcium sensitivity and hypertension. The association between variability in KCNMB1 and calcium antagonist response, however, has not been assessed.
Genetic samples were collected from 5979 patients in INVEST. Blood pressure response to verapamil SR and time to achieve blood pressure control was assessed in relation to Glu65Lys and Val110Leu genotypes. The primary outcome (all cause mortality, nonfatal myocardial infarction or nonfatal stroke) was compared between genotype groups, and interaction with verapamil SR therapy was assessed.
Systolic blood pressure response to verapamil SR did not differ by KCNMB1 genotype. Lys65 variant carriers, however, achieved blood pressure control earlier than Glu65Glu individuals [1.47 (interquartile ratio 2.77) versus 2.83 (interquartile ratio 4.17) months, P = 0.01] and were less likely to require multiple drugs at the time of blood pressure control (adjusted odds ratio 0.43, 95% confidence interval 0.19–0.95). Leu110 variant carriers had a reduced risk of primary outcome (hazard ratio 0.68, 95% confidence interval 0.47–0.998). Subgroup analysis revealed this finding to be more pronounced in verapamil SR-assigned patients (hazard ratio 0.587, 95% confidence interval 0.33–1.04) compared with atenolol-assigned patients (hazard ratio 0.946, 95% confidence interval 0.56–1.59). No difference was seen in the occurrence of the primary outcome compared by codon 65 genotype.
Our findings suggest that KCNMB1 genotype influences responsiveness to verapamil SR and risk of adverse cardiovascular outcomes.
KCNMB1; polymorphism; verapamil SR
The INternational VErapamil SR-Trandolapril STudy (INVEST), a randomized trial of 22,576 predominantly elderly patients with an average 2.7-year follow-up, compared a calcium antagonist led strategy (verapamil SR plus trandolapril) with a β blocker led strategy (atenolol plus hydrochlorothiazide) for hypertension treatment and prevention of cardiovascular outcomes in coronary artery disease. patients.
Patients received individualized dose and drug titration following a flexible, multi-drug, guideline-based treatment algorithm, with the objective of achieving optimal blood pressure (BP) control individualized for comorbidities (e.g., diabetes). The primary outcome (PO) was first occurrence of death (all-cause), nonfatal myocardial infarction or nonfatal stroke.
The strategies resulted in significant and very similar BP reduction with approximately 70% of patients in both strategies achieving BP control (< 140/90 mm Hg). Increasing number of office visits with BP in control was associated with reduced risk of the PO. Overall, there was no difference in the PO comparing the strategies, however new onset diabetes occurred more frequently in those assigned the atenolol strategy. This report summarizes findings from INVEST and puts them in perspective with our current state of knowledge derived from other large hypertension treatment trials. INVEST findings support that 1) BP reduction is important for prevention of adverse cardiovascular morbidity and mortality; and 2) selection of antihypertensive agents should be based on patient comorbidities and other risk factors (e.g. risk for diabetes) and not necessarily that any one drug be given to all.
Coronary artery disease; hypertension; atenolol; verapamil SR; trandolapril; hydrochlorothiazide; INVEST; new onset diabetes
Genetic variants of ACE are suspected risk factors in cardiovascular disease, but the alleles responsible for the variations remain unidentified. To search for regulatory polymorphisms, allelic angiotensin I–converting enzyme (ACE) mRNA expression was measured in 65 heart tissues, followed by genotype scanning of the ACE locus. Marked allelic expression imbalance (AEI) detected in five African-American subjects was associated with single-nucleotide polymorphisms (SNPs) (rs7213516, rs7214530, and rs4290) residing in conserved regions 2−3 kb upstream of ACE. Moreover, each of the SNPs affected transcription in reporter gene assays. SNPs rs4290 and rs7213516 were tested for associations with adverse cardiovascular outcomes in hypertensive patients with coronary disease (International Verapamil SR Trandolapril Study Genetic Substudy (INVEST-GENES), n = 1,032). Both SNPs were associated with adverse cardiovascular outcomes, largely attributable to nonfatal myocardial infarction in African Americans, showing an odds ratio of 6.16 (2.43−15.60) (P < 0.0001) for rs7213516. The high allele frequency in African Americans (16%) compared to Hispanics (4%) and Caucasians (<1%) suggests that these alleles contribute to variation between populations in cardiovascular risk and treatment outcomes.
The voltage-dependent L-type calcium channel α-subunit 1c (Cav1.2, CACNA1C) undergoes extensive mRNA splicing, leading to numerous isoforms with different functions. L-type calcium channel blockers are used in the treatment of hypertension and arrhythmias, but response varies between individuals. We have studied the interindividual variability in mRNA expression and splicing of CACNA1C, in 65 heart tissue samples, taken from heart transplant recipients.
Splice variants were measured quantitatively by polymerase chain reaction in 12 splicing loci of CACNA1C mRNA. To search for functional cis-acting polymorphisms, we determined allelic expression ratios for total CACNA1C mRNA and several splice variants using marker single nucleotide polymorphisms in exon 4 and exon 30.
Total CACNA1C mRNA levels varied ∼50-fold. Substantial splicing occurred in six loci generating two or more splice variants, some with known functional differences. Splice patterns varied broadly between individuals. Two heart tissues expressed predominantly the dihydropyridine-sensitive smooth muscle isoform of CACNA1C (containing exon 8), rather than the cardiac isoform (containing exon 8a). Lack of significant allelic expression imbalance, observed with total mRNA and several splice variants, argued against CACNA1C polymorphisms as a cause of variability. Taken together, highly variable splicing can cause profound phenotypic variations of CACNA1C function, potentially associated with disease susceptibility and response to L-type calcium channel blockers.
cis-acting polymorphism; L-type calcium channel α-subunit 1c; mRNA splicing
Malignant hyperthermia (MH) is an inherited pharmacogenetic disorder of skeletal muscle, characterised by an elevated calcium release from the skeletal muscle sarcoplasmic reticulum. The dihydropyridine receptor (DHPR) plays an essential role in excitation-contraction coupling and calcium homeostasis in skeletal muscle. This study focuses on the gene CACNA1S which encodes the α1 subunit of the DHPR, in order to establish whether CACNA1S plays a major role in MH susceptibility in the UK.
We investigate the CACNA1S locus in detail in 50 independent MH patients, the largest study to date, to identify novel variants that may predispose to disease and also to characterise the haplotype structure across CACNA1S.
We present CACNA1S cDNA sequencing data from 50 MH patients in whom RYR1 mutations have been excluded, and subsequent mutation screening analysis. Furthermore we present haplotype analysis of unphased CACNA1S SNPs to (1) assess CACNA1S haplotype frequency differences between susceptible MH cases and a European control group and (2) analyse population-based association via clustering of CACNA1S haplotypes based on disease risk.
The study identified a single potentially pathogenic change in CACNA1S (p.Arg174Trp), and highlights that the haplotype structure across CACNA1S is diverse, with a high degree of variability.
The calcium channel CACNA1A gene encodes the pore-forming, voltage-sensitive subunit of the voltage-dependent calcium Ca(v)2.1 type channel. Mutations in this gene have been linked to several human disorders, including familial hemiplegic migraine, episodic ataxia 2 and spinocerebellar ataxia type 6. The mouse homologue, Cacna1a, is associated with the tottering, Cacna1atg, mutant series. Here we describe two new missense mutant alleles, Cacna1atg-4J and Cacna1aTg-5J. The Cacna1atg-4J mutation is a valine to alanine mutation at amino acid 581, in segment S5 of domain II. The recessive Cacna1atg-4J mutant exhibited the ataxia, paroxysmal dyskinesia and absence seizures reminiscent of the original tottering mouse. The Cacna1atg-4J mutant also showed altered activation and inactivation kinetics of the Ca(v)2.1 channel, not previously reported for other tottering alleles. The semi-dominant Cacna1aTg-5J mutation changed a conserved arginine residue to glutamine at amino acid 1252 within segment S4 of domain III. The heterozygous mouse was ataxic and homozygotes rarely survived. The Cacna1aTg-5J mutation caused a shift in both voltage activation and inactivation to lower voltages, showing that this arginine residue is critical for sensing Ca(v)2.1 voltage changes. These two tottering mouse models illustrate how novel allelic variants can contribute to functional studies of the Ca(v)2.1 calcium channel.
tottering alleles; Ca(v)2.1 calcium channels; semi-dominant mutation
While numerous SNPs in Chromosome 9p21 have been associated with coronary artery disease (CAD) and incident MI in Caucasians, there are limited and conflicting reports on the association of this locus with prognosis in Caucasians with existing CAD and no reports in blacks or Hispanics. We investigated the hypothesis that 9p21 polymorphisms are associated with increased risk for adverse cardiovascular outcomes in patients with documented CAD.
Methods and Results
We studied the association of 155 chromosome 9p21 SNPs with adverse outcomes among hypertensive CAD patients of multiple races/ethnicities in INVEST GENES (the INternational VErapamil SR Trandolapril STudy GENetic Substudy, n= 1,460, n = 5,979 for 2 SNPs) and with replication testing of 4 SNPs in the INFORM (INvestigation oF Outcomes from acute coronary syndRoMe; n=714) study of acute coronary syndrome (ACS) patients. In INVEST, the haplotype comprised of the risk allele for the widely reported 9p21 SNPs was associated with better prognosis in Caucasians (OR, 95% CI: 0.72, 0.57–0.92, p = 0.0085) but not blacks (1.21, 0.68–1.24, p = 0.52) or Hispanics (0.96, 0.65–1.44, p=0.86). A less commonly reported LD block was associated with worse prognosis in INVEST among both Caucasians (OR=1.52 (1.20–1.93), p = 0.0006) and African Americans (OR = 4.11 (1.55–10.88), p = 0.004).
Our findings suggest previously reported chromosome 9p21 SNPs, which predict incident CAD, are not associated with higher risk for adverse outcomes in patients with established CAD. The less commonly reported LD block warrants further investigation.
chromosome 9p21; cardiovascular outcomes; genetic polymorphisms; INVEST; INFORM
Hypertensive diabetes individuals are at higher risk for cardiovascular events and progression to end stage renal disease. Several well conducted clinical trials indicate that aggressive treatment of hypertension in individual with diabetes reduces these complications. Combinations of two or more antihypertensive drugs are frequently required to reach the target blood pressure and to improve the cardiovascular and renal outcomes in these patients. There are physiological and clinical rationales for renin-angiotensin system blockade in hypertensive diabetics. Trandolapril/verapamil sustained released (SR) is a fixed-dose combination of trandolapril and a sustained release formulation of verapamil and indicated in treatment of hypertension in patients who require more than one drug to reach target blood pressure. The antihypertensive efficacy of trandolapril/verapamil SR has been evaluated extensively in large trials. In the INVEST trial, a verapamil SR-based treatment strategy that included trandolapril in most patients was effective in reducing the primary outcome in hypertensive patients with coronary artery disease. The new onset of diabetes was also significantly lower in the verapamil SR/trandolapril treatment group in comparison with those on the atenolol/hydroclorothiazide treatment group. The BErgamo NEphrologic DIabetes Complications Trial (BENEDICT) documented that in hypertensive diabetes and normoalbuminuria, trandolapril plus verapamil or trandolapril alone delayed the onset of microalbuminuria independent of their blood pressure-reducing effect. Thus, trandolapril/verapamil is an effective option for treatment of hypertensive diabetes patients requiring more than one agent to achieve target blood pressure.
diabetes mellitus; hypertension; trandolapril; verapamil SR
Individual differences in the sensitivity to fentanyl, a widely used opioid analgesic, lead to different proper doses of fentanyl, which can hamper effective pain treatment. Voltage-activated Ca2+ channels (VACCs) play a crucial role in the nervous system by controlling membrane excitability and calcium signaling. Cav2.3 (R-type) VACCs have been especially thought to play critical roles in pain pathways and the analgesic effects of opioids. However, unknown is whether single-nucleotide polymorphisms (SNPs) of the human CACNA1E (calcium channel, voltage-dependent, R type, alpha 1E subunit) gene that encodes Cav2.3 VACCs influence the analgesic effects of opioids. Thus, the present study examined associations between fentanyl sensitivity and SNPs in the human CACNA1E gene in 355 Japanese patients who underwent painful orofacial cosmetic surgery, including bone dissection. We first conducted linkage disequilibrium (LD) analyses of 223 SNPs in a region that contains the CACNA1E gene using genomic samples from 100 patients, and a total of 13 LD blocks with 42 Tag SNPs were observed within and around the CACNA1E gene region. In the preliminary study using the same 100 genomic samples, only the rs3845446 A/G SNP was significantly associated with perioperative fentanyl use among these 42 Tag SNPs. In a confirmatory study using the other 255 genomic samples, this SNP was also significantly associated with perioperative fentanyl use. Thus, we further analyzed associations between genotypes of this SNP and all of the clinical data using a total of 355 samples. The rs3845446 A/G SNP was associated with intraoperative fentanyl use, 24 h postoperative fentanyl requirements, and perioperative fentanyl use. Subjects who carried the minor G allele required significantly less fentanyl for pain control compared with subjects who did not carry this allele. Although further validation is needed, the present findings show the possibility of the involvement of CACNA1E gene polymorphisms in fentanyl sensitivity.
Liver X receptor-α (LXRA) is a nuclear receptor that regulates genes important in cholesterol homeostasis and inflammation. Several single nucleotide polymorphisms (SNPs) in the LXRA gene have been previously associated with metabolic phenotypes (dyslipidemia and elevated BMI). Metabolic dysregulation is a major contributor to coronary disease; therefore, we assessed LXRA in INVEST-GENES, a genetic-substudy of a large clinical trial in patients with hypertension and coronary artery disease.
Seven tag SNPs in the LXRA gene region (NR1H3) were selected for study: rs11039149, rs12221497, rs2279238, rs7120118, rs326213, rs11039159 and rs10501321. 1059 subjects were genotyped from the INVEST-GENES case-control set (Verapamil-SR or Atenolol based treatment strategies), comprised of 297 cases frequency matched approximately 2.5:1 with event-free controls by sex and race. The primary outcome was defined as first occurrence of all-cause death, nonfatal MI, or nonfatal stroke. Adjusted odds ratios (OR) were calculated using logistic regression.
Three of the seven SNPs were associated with significant effects on the primary outcome in Non-Blacks. The variant G allele of rs11039149 and the variant A allele of rs12221497 were associated with reduced risk of experiencing the primary outcome (OR: 0.62, CI: 0.45-0.85, P=0.003 and OR: 0.60, CI: 0.39-0.91, P=0.016 respectively). The rs2279238 genotype was associated with a significant increase in risk for the primary outcome (OR: 1.42, CI: 1.03-1.95, P=0.03). Furthermore, there was a significant genotype-treatment strategy interaction for carriers of the variant T allele of rs2279238 (OR for Verapamil SR strategy compared to Atenolol: 2.86, CI: 1.50-5.46, P=0.0015). Diplotype analyses revealed that the SNPs are rarely co-inherited and support the directionally opposite effects of the SNPs on the primary outcome.
LXRA genotypes were associated with variable risk for cardiovascular outcomes and pharmacogenetic effect in INVEST-GENES. These novel findings suggest LXRA is a genetic/pharmacogenetic target that should be further explored.
LXRA; Nuclear Receptor; Pharmacogenetics; Polymorphisms; Cardiovascular Disease; Hypertension; Atenolol; Verapamil
The CACNA1C gene (alpha 1C subunit of the L-type voltage-gated calcium channel) has been identified as a risk gene for both bipolar disorder and schizophrenia but the mechanism of association has not been explored.
To identify the neural system mechanism that explains the genetic association between the CACNA1C gene and psychiatric illness, using neuroimaging and human brain expression.
We used BOLD fMRI to measure brain activation in circuitries related to bipolar disorder and schizophrenia by comparing CACNA1C genotype groups in healthy subjects. We tested the effect of genotype on mRNA levels of CACNA1C in post-mortem human brain. A case-control analysis was used to determine the association of CACNA1C genotype and schizophrenia.
National Institutes of Health Clinical Center
Healthy Caucasian men and women participated in the fMRI study. Post-mortem samples from normal human brains were used for the brain expression study. Patients with schizophrenia and healthy subjects were used in the case-control analysis.
Main Outcome Measures
BOLD fMRI, mRNA levels in post-mortem brain samples, and genetic association with schizophrenia
The risk associated single nucleotide polymorphism (SNP rs1006737) in CACNA1C predicted increased hippocampal activity during emotional processing (puncorr=0.001, pFDR=0.052, Z=3.20) and increased prefrontal activity during executive cognition (puncorr=2.8e-05, pFDR=0.011, Z=4.03). The risk SNP also predicted increased expression of CACNA1C mRNA in human brain (p=0.0017). CACNA1C was associated with schizophrenia in our case-control sample (OR 1.77, p=0.026).
The risk associated SNP in CACNA1C maps to circuitries implicated in genetic risk for both bipolar disorder and schizophrenia. Its effects in human brain expression implicate a molecular and neural systems mechanism for the clinical genetic association.
Hypokalemic periodic paralysis (HypoPP) is an autosomal dominant disorder which is characterized by periodic attacks of muscle weakness associated with a decrease in the serum potassium level. The skeletal muscle calcium channel α-subunit gene CACNA1S is a major disease-causing gene for HypoPP, however, only three specific HypoPP-causing mutations, Arg528His, Arg1,239His and Arg1,239Gly, have been identified in CACNA1S to date. In this study, we studied a four-generation Chinese family with HypoPP with 43 living members and 19 affected individuals. Linkage analysis showed that the causative mutation in the family is linked to the CACNA1S gene with a LOD score of 6.7. DNA sequence analysis revealed a heterozygous C to G transition at nucleotide 1,582, resulting in a novel 1,582C→G (Arg528Gly) mutation. The Arg528Gly mutation co-segregated with all affected individuals in the family, and was not present in 200 matched normal controls. The penetrance of the Arg528Gly mutation was complete in male mutation carriers, however, a reduced penetrance of 83% (10/12) was observed in female carriers. No differences were detected for age-at-onset and severity of the disease (frequency of symptomatic attacks per year) between male and female patients. Oral intake of KCl is effective in blocking the symptomatic attacks. This study identifies a novel Arg528Gly mutation in the CACNA1S gene that causes HypoPP in a Chinese family, expands the spectrum of mutations causing HypoPP, and demonstrates a gender difference in the penetrance of the disease.
Hypokalemic periodic paralysis; Skeletal muscle calcium channel; Mutation; CACNA1S; Ion channel; CACNA1S: Skeletal muscle voltage-gated calcium channel α-subunit; HyperPP: Hyperkalemic periodic paralysis; HypoPP: Hypokalemic periodic paralysis; KCNE3: Voltage-gated potassium channel β subunit gene; PCR: Polymerase chain reaction; RFLP: Restriction fragment length polymorphism; SCN4A: Skeletal muscle voltage-gated sodium channel α-subunit
Polymorphisms (SNPs) within the regulatory β2 subunit of the voltage-gated calcium channel (CACNB2) may contribute to variable treatment response to antihypertensive drugs and adverse cardiovascular outcomes.
Methods and Results
SNPs in CACNB2 from 60 ethnically diverse individuals were identified and characterized. Three common SNPs (rs2357928, rs7069292 and rs61839258) and a GWAS identified intronic SNP (rs11014166) were genotyped for a clinical association study in 5,598 hypertensive patients with coronary artery disease randomized to a beta-blocker (BB) or a calcium channel blocker (CCB) treatment strategy in INVEST-GENES. Reporter gene assays were conducted on the promoter SNP showing association with clinical outcomes. Twenty-one novel SNPs were identified. A promoter A>G SNP (rs2357928) was found to have significant interaction with treatment strategy for adverse cardiovascular outcomes (p for interaction = 0.002). In Caucasians, rs2357928 GG patients randomized to CCB were more likely to experience adverse outcome than those randomized to BB treatment strategy, with adjusted hazard ratio (CCB vs. BB) of 2.35 (1.19-4.66), p = 0.014. There was no evidence for such treatment difference in AG (1.16, 0.75-1.79, p = 0.69) and AA individuals (0.63, 0.36-1.11, p = 0.11). This finding was consistent in Hispanics and African Americans. CACNB2 rs11014166 showed similar pharmacogenetic effect in Hispanics, but not in Caucasians or African Americans. Reporter assay analysis of rs2357928 showed a significant increase in promoter activity for the G allele compared to the A allele.
These data suggest genetic variation within CACNB2 may influence treatment related outcomes in high risk hypertensive patients.
Clinical Trial Registration Information
Clinical trial identifier: NCT00133692, URL: http://clinicaltrials.gov/ct/gui/show/NCT00133692).
Genetic variations; CACNB2; hypertension; cardiovascular outcomes; INVEST-GENES
Our understanding of the growing population of very old patients (aged ≥80 years) with coronary artery disease and hypertension is limited, particularly the relationship between blood pressure and adverse outcomes.
This was a secondary analysis of the INternational VErapamil SR-Trandolapril STudy (INVEST), which involved 22,576 clinically stable hypertensive coronary artery disease patients aged ≥50 years. The patients were grouped by age in 10-year increments (aged ≥80, n = 2180; 70–<80, n = 6126; 60–<70, n = 7602; <60, n =6668). Patients were randomized to either verapamil SR- or atenolol-based treatment strategies, and primary outcome was first occurrence of all-cause death, nonfatal myocardial infarction, or nonfatal stroke.
At baseline, increasing age was associated with higher systolic blood pressure, lower diastolic blood pressure, and wider pulse pressure (P <.001). Treatment decreased systolic, diastolic, and pulse pressure for each age group. However, the very old retained the widest pulse pressure and the highest proportion (23.6%) with primary outcome. The adjusted hazard ratio for primary outcomes showed a J-shaped relationship among each age group with on-treatment systolic and diastolic pressures. The systolic pressure at the hazard ratio nadir increased with increasing age, highest for the very old (140 mm Hg). However, diastolic pressure at the hazard ratio nadir was only somewhat lower for the very old (70 mm Hg). Results were independent of treatment strategy.
Optimal management of hypertension in very old coronary artery disease patients may involve targeting specific systolic and diastolic blood pressures that are higher and somewhat lower, respectively, compared with other age groups.
Age; Blood pressure control; Coronary artery disease; Elderly; Epidemiology; Hypertension
Factors such as age and race/ethnicity might influence blood pressure (BP) response to drugs. Therapeutic response to the angiotensin-converting enzyme inhibitor trandolapril used as add-on therapy to stable calcium channel blocker therapy with verapamil sustained release 240 mg was addressed in a racially/ethnically diverse group of 1,832 hypertensive patients with coronary artery disease. Furthermore, the association with a polymorphism (1166A→C) in the angiotensin II type 1 receptor gene (AGTR1) was tested. BP response was compared between groups using analysis of covariance after adjustment for covariates associated with BP response. Genotyping was performed using polymerase chain reaction and pyrosequencing. Trandolapril decreased mean unadjusted systolic and diastolic BPs by −9.1 ± 17.3 (SD) and −4.1 ± 10.1 mm Hg, respectively. The percentage of patients with BP under control (<140/90 mm Hg) increased from 6.7% to 41.3% (p <0.0001). Adjusted BP response was significantly associated with age and baseline systolic and diastolic BP (p <0.0001). Whereas the decrease in systolic BP was more pronounced in younger patients, the opposite was observed for diastolic BP decrease. Diastolic BP response was also significantly associated with race. Specifically, the adjusted diastolic BP decrease was significantly smaller in Hispanics and blacks than whites (p = 0.0032 and p = 0.0069, respectively). However, Hispanics achieved a decrease in systolic BP and an increase in BP control similar to the other ethnic groups. There was no genetic association between AGTR1 1166A→C genotype and BP response. In conclusion, trandolapril add-on therapy was effective in increasing BP control, with age and baseline BP associated with both systolic and diastolic BP response. Race was associated with diastolic BP response, although the difference is likely not to be clinically significant and AGTR1 genotype was not associated with BP response.
The CACNA2D2 gene, a new subunit of the Ca2+-channel complex, was identified in the homozygous deletion region of chromosome 3p21.3 in human lung and breast cancers. Expression deficiency of the CACNA2D2 in cancer cells suggests a possible link of it to Ca2+ signaling in the pathogenesis of lung cancer and other cancers. We investigated the effects of overexpression of CACNA2D2 on intracellular Ca2+ contents, mitochondria homeostasis, cell proliferation, and apoptosis by adenoviral vector-mediated wild-type CACNA2D2 gene transfer in 3p21.3-deficient nonsmall cell lung cancer cell lines. Exogenous expression of CACNA2D2 significantly inhibited tumor cell growth compared with the controls. Overexpression of CACNA2D2 induced apoptosis in H1299 (12.5%), H358 (13.7%), H460 (22.3%), and A549 (50.1%) cell lines. Levels of intracellular free Ca2+ were elevated in AdCACNA2D2-transduced cells compared with the controls. Mitochondria membrane depolarization was observed prior to apoptosis in Ad-CACNA2D2 and Adp53-transduced H460 and A549 cells. Release of cyt c into the cytosol, caspase 3 activation, and PARP cleavage were also detected in these cells. Together, these results suggest that one of the pathways in CACNA2D2-induced apoptosis is mediated through disruption of mitochondria membrane integrity, the release of cyt c, and the activation of caspases, a process that is associated with regulation of cytosolic free Ca2+ contents.
tumor suppressor genes; apoptosis; calcium channel proteins; human chromosome 3p21.3; lung cancer
The α-adducin (ADD1) Gly460Trp polymorphism has been associated with hypertension and response to diuretic therapy, but controversy exists.
The present study was conducted to prospectively investigate the relationship between the ADD1 Gly460Trp polymorphism, diuretic use, and adverse cardiovascular outcomes among 5,979 hypertensive coronary artery disease patients, who participated in the INternational VErapamil SR-trandolapril STudy (INVEST) and provided genomic DNA. The primary outcome was defined as first occurrence of nonfatal stroke, nonfatal myocardial infarction, or all-cause death. Secondary outcomes were the components of the primary outcome. Ancestry informative markers were used to control for population stratification.
In Blacks, ADD1 variant carriers were at higher risk for a primary outcome event than wild-type homozygotes (adjusted hazard ratio (HR) 2.62; 95% confidence interval (CI) 1.23–5.58; p = .012), with a similar trend in Whites and Hispanics, albeit a smaller magnitude of effect (adjusted HR 1.43, 0.86–2.39 in Hispanics; 1.24, 0.90–1.71 in Whites). Secondary outcome analysis showed that the all-cause death was driving the differences in primary outcomes by genotype. There was no interaction between the ADD1 polymorphism and diuretic use for either primary outcome or secondary outcomes.
In hypertensive patients with coronary artery disease, black ADD1 variant carriers showed a 2.6-fold excess risk for a primary outcome event and an 8-fold increase risk of death. White and Hispanic ADD1 variant carriers showed an increased but nonsignificant excess risk. However, the effect of diuretic use on risk of cardiovascular outcomes did not vary by ADD1 carrier status.
pharmacogenetics; ADD1; diuretics; cardiovascular outcomes
To determine the relationship between resting heart rate (RHR) and adverse outcomes in coronary artery disease (CAD) patients treated for hypertension with different RHR-lowering strategies.
Methods and results
Time to adverse outcomes (death, non-fatal myocardial infarction, or non-fatal-stroke) and predictive values of base-line and follow-up RHR were assessed in INternational VErapamil-SR/trandolapril STudy (INVEST) patients randomized to either a verapamil-SR (Ve) or atenolol (At)-based strategy. Higher baseline and follow-up RHR were associated with increased adverse outcome risks, with a linear relationship for baseline RHR and J-shaped relationship for follow-up RHR. Although follow-up RHR was independently associated with adverse outcomes, it added less excess risk than baseline conditions such as heart failure and diabetes. The At strategy reduced RHR more than Ve (at 24 months, 69.2 vs. 72.8 beats/min; P < 0.001), yet adverse outcomes were similar [Ve 9.67% (rate 35/1000 patient-years) vs. At 9.88% (rate 36/1000 patient-years, confidence interval 0.90–1.06, P = 0.62)]. For the same RHR, men had a higher risk than women.
Among CAD patients with hypertension, RHR predicts adverse outcomes, and on-treatment RHR is more predictive than baseline RHR. A Ve strategy is less effective than an At strategy for lowering RHR but has a similar effect on adverse outcomes.
Coronary artery disease; Atenolol; Resting heart rate; Adverse outcomes; INVEST; Verapamil-SR
Our understanding of the growing population of revascularized patients with hypertension is limited. We retrospectively analyzed the International Verapamil SR-Trandolapril Study, which randomized coronary artery disease patients with hypertension to either verapamil SR- or atenolol-based treatment strategies, focusing on characteristics and outcomes of 6166 previously revascularized patients compared with 16 410 nonrevascularized patients. Revascularized patients had a history of coronary artery bypass grafting (45.2%), percutaneous coronary intervention (42.1%), or both (12.8%). Compared with nonrevascularized patients, revascularized patients at baseline demonstrated a higher prevalence of coronary artery disease risk factors and risk conditions (P<0.001). This higher prevalence was the principal cause of a higher incidence of primary outcome (death, nonfatal myocardial infarction, or nonfatal stroke) among revascularized patients (14.2% versus 8.5% for nonrevascularized patients; P<0.001). However, both patient groups demonstrated a relatively low incidence of subsequent revascularization (5.1% versus 1.5% respectively; P<0.0001). Associations between adjusted hazard ratio for primary outcome and follow-up blood pressure appeared “J shaped” for both patient groups. Because, as a group, revascularized patients with hypertension had worse outcomes compared with nonrevascularized patients, management of blood pressure to a specific target in future studies could result in improved outcomes.
hypertension; blood pressure; coronary artery disease; revascularization; coronary artery bypass grafting; percutaneous coronary intervention; epidemiology
Calcium is an important intracellular messenger that mediates many biological processes that are relevant to the malignant process. Calcium ion channels are key in controlling the intracellular calcium, and little is known about their role in human cancer.
We used qPCR and pyrosequencing to investigate expression and epigenetic regulation of the calcium channel regulatory subunit α2δ-3 (CACNA2D3) in breast cancer cell lines, primary cancers and metastatic lesions.
Expression of CACNA2D3 mRNA is regulated in breast cancer cell lines by methylation in the CpG island located in the 5′ regulatory region of the gene. Expression is upregulated by azacytidine (AZA) in cells with CpG island methylation but unaffected in cells lacking methylation. In primary breast carcinomas, methylation is more common in cancers, which subsequently relapse with loco-regional and, particularly, visceral metastatic disease in both oestrogen receptor-α (ER)-positive and -negative cases. Furthermore, CACNA2D3 CpG island is frequently methylated in breast cancer that has metastasised to the central nervous system.
Methylation-dependent transcriptional silencing of CACNA2D3 may contribute to the metastatic phenotype of breast cancer. Analysis of methylation in the CACNA2D3 CpG island may have potential as a biomarker for risk of development of metastatic disease.
breast cancer; metastasis; calcium channels; epigenetics
Due to time-dependent confounding by blood pressure and differential loss to follow-up, it is difficult to estimate the effectiveness of aggressive versus conventional antihypertensive combination therapies in non-randomized comparisons.
We utilized data from 22,576 hypertensive coronary artery disease patients, prospectively enrolled in the INternational VErapamil-Trandolapril STudy (INVEST). Our post-hoc analyses did not consider the randomized treatment strategies, but instead defined exposure time-dependently as aggressive treatment (≥3 concomitantly used antihypertensive medications) versus conventional treatment (≤2 concomitantly used antihypertensive medications). Study outcome was defined as time to first serious cardiovascular event (non-fatal myocardial infarction, non-fatal stroke, or all-cause death). We compared hazard ratio (HR) estimates for aggressive vs. conventional treatment from a Marginal Structural Cox Model (MSCM) to estimates from a standard Cox model. Both models included exposure to antihypertensive treatment at each follow-up visit, demographics, and baseline cardiovascular risk factors, including blood pressure. The MSCM further adjusted for systolic blood pressure at each follow-up visit, through inverse probability of treatment weights.
2,269 (10.1%) patients experienced a cardiovascular event over a total follow-up of 60,939 person-years. The HR for aggressive treatment estimated by the standard Cox model was 0.96 (95% confidence interval 0.87-1.07). The equivalent MSCM, which was able to account for changes in systolic blood pressure during follow-up, estimated a HR of 0.81 (95% CI 0.71-0.92).
Using a MSCM, aggressive treatment was associated with a lower risk for serious cardiovascular outcomes compared to conventional treatment. In contrast, a standard Cox model estimated similar risks for aggressive and conventional treatments.
Clinicaltrials.gov Identifier: NCT00133692
Blood pressure; Hypertension; Time-dependent confounding; Marginal structural models
Polymorphisms in the endothelial nitric oxide synthase (NOS3) gene increase susceptibility to hypertension and cardiovascular disease. We examined genetic and pharmacogenetic associations between NOS3 polymorphisms, blood pressure (BP) control, and cardiovascular events in elderly, hypertensive coronary artery disease (CAD) patients.
Patients with CAD were randomly assigned to either verapamil SR– or atenolol-based antihypertensive treatment and followed for cardiovascular events. Cases (all-cause death, nonfatal myocardial infarction (MI), or nonfatal stroke) and an age-, sex-, race/ethnicity-matched control population were genotyped for the -786T>C and Glu298>Asp polymorphisms in NOS3. On-treatment BP and BP control were compared across genotype groups. Logistic regression was performed to estimate odds ratios (ORs) for the -786T>C and Glu298>Asp polymorphisms in the combined population and in randomized treatment groups.
Genotype data were available for 256 cases and 769 controls. Among controls, mean on-treatment BP differed according to -786T>C genotype (T/T 137/78 mm Hg, T/C 133/76 mm Hg, C/C 133/75 mm Hg; P = 0.0007 for systolic, P = 0.09 for diastolic) which corresponded to differing rates of BP control (T/T 63%, T/C 72%, C/C 88%; P = 0.002). Neither polymorphisms was associated with case status, with or without regard to assigned treatment.
The -786T>C, but not the Glu298>Asp variant of NOS3, may correlate with BP but do not appear to be associated with incident cardiovascular events in patients with established cardiovascular disease. The antihypertensive treatment approach did not appear to alter the genetic contribution to either BP control or cardiovascular events.
One of the most consistent genetic findings to have emerged from bipolar disorder genome wide association studies (GWAS) is with CACNA1C, a gene that codes for the α1C subunit of the Cav1.2 voltage-dependent L-type calcium channel (LTCC). Genetic variation in CACNA1C have also been associated with depression, schizophrenia, autism spectrum disorders, as well as changes in brain function and structure in control subjects who have no diagnosable psychiatric illness. These data are consistent with a continuum of shared neurobiological vulnerability between diverse—Diagnostic and Statistical Manual (DSM) defined—neuropsychiatric diseases. While involved in numerous cellular functions, Cav1.2 is most frequently implicated in coupling of cell membrane depolarization to transient increase of the membrane permeability for calcium, leading to activation and, potentially, changes in intracellular signaling pathway activity, gene transcription, and synaptic plasticity. Cav1.2 is involved in the proper function of numerous neurological circuits including those involving the hippocampus, amygdala, and mesolimbic reward system, which are strongly implicated in psychiatric disease pathophysiology. A number of behavioral effects of LTCC inhibitors have been described including antidepressant-like behavioral actions in rodent models. Clinical studies suggest possible treatment effects in a subset of patients with mood disorders. We review the genetic structure and variation of CACNA1C, discussing relevant human genetic and clinical findings, as well as the biological actions of Cav1.2 that are most relevant to psychiatric illness.
Calcium channel; CACNA1C; Genome wide association study; Bipolar disorder; Depression; Schizophrenia; Psychiatric genetics
Mutations in the CACNA1A gene are associated with episodic ataxia type 2 (EA2) and spinocerebellar ataxia type 6 (SCA6). CACNA1A encodes the α-subunit of the P/Q-type calcium channel or CaV2.1, which is highly enriched in the cerebellum. It is one of the main channels linked to synaptic transmission throughout the human central nervous system. Here, we compare recent advances in the understanding of the genetic changes that underlie EA2 and SCA6 and what these new findings suggest about the mechanism of the disease.
Spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2) and familial hemiplegic migraine (FHM) have been known as allelic disorders, which are caused by the alteration of the alpha1A voltage-dependent calcium channel subunit. Expansions of the CAG repeat in the CACNA1A gene on the short arm of the chromosome 19 induce SCA6, and point mutations in the same gene are responsible for EA2 and FHM. In recent studies, both SCA6 and EA2 have been concurrently found in families with 26 CAG repeats without previously reported point mutations either in coding sequences or in intron-exon junctions. We describe a Korean family with CAG26 repeats in the CACNA1A gene. Some of the affected family members had progressive ataxia typical of SCA6 whereas others had episodic vertigo responsive to acetazolamide typical of EA2. Our family support that SCA6 and EA2 are allelic disorders with a high phenotypic variability.