A polymorphism in the angiotensin-converting enzyme gene is associated with smoking behavior

Association between the ACE-I/D polymorphism and nicotine dependence amongst patients with lung cancer

The biologically active peptide angiotensin II is cleaved from angiotensinogen by the renin and the angiotensin-converting enzyme (ACE), an enzymatic cascade known as the renin-angiotensin system (RAS). RAS may be important in the etiology of nicotine dependence by influencing dopaminergic signaling. In the present study, the association between an insertion/deletion (I/D) polymorphism of ACE and nicotine dependence amongst patients with lung cancer was assessed. To date, several studies have shown the relevance of this polymorphic variant in both nicotine dependence and lung cancer. However, the present study is the first to address the potential role of the ACE-I/D polymorphism in nicotine dependence among patients with lung cancer. Genotyping was performed in 305 patients with lung cancer (males/females, 214/91). Significantly more male smokers had the ACE-I allele compared with male non-smokers (44.9 vs. 20.0%; P<0.05). The risk of smoking was ~5-fold higher for males with the ACE-I allele (ACE-II homozygous and ACE-ID heterozygous) vs. ACE-DD homozygous (odds ratio, 5.47; 95% confidence interval, 1.4-21.9; P=0.016). The pack-year smoking history in a subgroup of females with squamous cell carcinoma carrying the ACE-I allele was significantly lower compared with ACE-DD (37.1±14.1 vs. 57.0±29.1; F=4.5; P=0.046). The ACE-I/D polymorphism accounted for 17.6% of the smoking severity in this patient group (β, -0.42; multiple R² change, 0.176; P=0.046). These results suggest that the ACE-I/D polymorphism contributes to the risk of nicotine dependence and smoking severity in lung cancer patients in a sex-specific manner.

The lack of association between angiotensin-converting enzyme gene insertion/deletion polymorphism and nicotine dependence in multiple sclerosis

OBJECTIVE

Blood-borne angiotensin II is generated from angiotensinogen via cleavage by renin and angiotensin-converting enzyme (ACE), an enzymatic cascade known as the renin-angiotensin system (RAS). Several lines of evidence indicate that ACE, beyond its classical role of mediating blood pressure regulation, might contribute to the etiology of substance addictions by influencing dopaminergic signaling. A functional insertion/deletion (I/D) polymorphism of the ACE gene was associated with risk for being a smoker among individuals with depression and with smoking severity in studies comprising patients with depression and healthy controls. Several reports have described significantly increased ACE activity in cerebrospinal fluid and serum among MS patients. Furthermore, in our previous work with MS patients from Croatian and Slovenian populations, we demonstrated that the ACE-I/D polymorphism contributes to an elevated MS risk among male patients. Here we investigated whether the ACE-I/D polymorphism might influence smoking behavior among patients with MS.

PATIENTS AND METHODS

Genotyping was performed in 521 patients (males/females: 139/382) using polymerase chain reaction.

RESULTS

We revealed no significant differences in ACE genotype and allele frequencies between smokers and nonsmokers and no significant association between the ACE-I/D polymorphism and either pack-year smoking history or number of cigarettes smoked daily (p > .05, respectively).

CONCLUSION

The ACE-I/D polymorphism does not contribute either to risk for nicotine dependence or to smoking severity among MS patients. In the context of reports on the ACE-I/D polymorphism and nicotine dependence among healthy controls and patients with depression, we may speculate that the mechanism by which this polymorphism influences nicotine dependence risk differs in MS compared to depression, although not compared to a healthy population. In addition to angiotensin II, other potential ACE substrates, such as substance P and neurotensin, which also influence dopaminergic neurotransmission (and are proposed to be associated with MS), may deserve study in future.

An increased circulating angiotensin II concentration is associated with hypoadiponectinemia and postprandial hyperglycemia in men with nonalcoholic fatty liver disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is a condition associated with type 2 diabetes (T2D). Insulin resistance, a common pathogenesis of NAFLD and T2D, is partially caused by alterations in angiotensin II (Ang II) and is accompanied by hypoadiponectinemia. We aimed to investigate whether the circulating Ang II and adiponectin concentrations are related to hyperglycemia in male NAFLD patients.

METHODS

Thirty-five controls and 85 NAFLD patients without prior known T2D were enrolled. All participants were non-smoking men who performed 75-g oral glucose tolerance tests. According to the American Diabetes Association (ADA) criteria, the NAFLD patients were divided into the euglycemia and hyperglycemia groups. The NAFLD patients with hyperglycemia were further divided into the isolated impaired fasting glucose (I-IFG) and postprandial hyperglycemia subgroups. The fasting serum Ang II and adiponectin concentrations were measured.

RESULTS

Among the 85 NAFLD patients, 40 (47%) had hyperglycemia, including I-IFG (18%) and postprandial hyperglycemia (29%). The serum Ang II concentrations in the euglycemia and hyperglycemia groups were significantly higher than those observed in the control and euglycemia groups, respectively; whereas the serum adiponectin concentrations were significantly lower. The serum Ang II concentrations were significantly higher in the postprandial hyperglycemia subgroup than in the I-IFG subgroup. The serum Ang II and adiponectin concentrations were found to be independent predictors of hyperglycemia in the NAFLD patients. The serum Ang II concentration was significantly associated with the serum adiponectin and 2-hour postprandial glucose concentrations in the NAFLD patients.

CONCLUSION

An increased circulating Ang II concentration is associated with hypoadiponectinemia and postprandial hyperglycemia in male NAFLD patients and may be involved in the pathogenesis of T2D in NAFLD patients.