Abstract P6-10-16: High circulating levels of adrenomedullin are associated with metabolic syndrome and low cardiorespiratory fitness in <i>BRCA1</i> and <i>BRCA2</i> mutation carriers
Authors: Jacqueline Lammert, Sabine Grill, Maryam Yahiaoui-Doktor, Maryam Basrai, Joachim Struck, Oliver Hartmann, Martin Halle, Marion Kiechle
Journal: Cancer Research (2020)

Abstract BACKGROUND: Risk factors for cardiovascular disease (CVD) and breast cancer overlap substantially. Identification of the underlying mechanisms associated with this co-occurrence is of great public health importance. Adrenomedullin (AM) is an almost ubiquitously expressed peptide with vasodilator and natriuretic properties. Previous studies have observed a link between high AM levels and worse prognosis in patients with myocardial infarction and heart failure, indicating a crucial role in the pathophysiology of CVD. Moreover, AM is expressed in 80% of sporadic breast cancers, and the degree of expression is associated with tumour growth, local tumour progression and bone metastases. High plasma AM levels are linked to arterial hypertension, diabetes, obesity and smoking. Preliminary evidence suggests that AM influences the osteoclast differentiation mediated by Receptor Activator of NF-κB Ligand (RANKL), an important signalling pathway in BRCA1-associated breast tumorigenesis. OBJECTIVE: Besides an elevated risk of breast cancer, recent studies revealed that BRCA mutation carriers are potentially at higher cardiovascular risk. The value of AM in BRCA mutation carriers is unknown. The aim of this study was to examine circulating plasma AM levels in BRCA mutation carriers and assess their association with modifiable risk factors. METHODS: AM concentrations were measured in 290 BRCA1/2 mutation carriers without overt CVD, participating in the randomized controlled LIBRE study (NCT numbers: NCT02087592, NCT02516540), by an immunoassay (sphingotest® bio-ADM®). Subjects were classified into high versus low AM levels based on the median plasma AM level in the entire cohort (13.9 pg/mL). Univariate logistic regression models were used to estimate the odds ratio (OR) of having high circulating AM levels by metabolic syndrome (MetS), cardiorespiratory fitness (CRF), body mass index (BMI), circulating insulin, smoking, current age, BRCA mutation status (BRCA1 or BRCA2) and previous diagnosis of breast cancer. MetS was defined in accordance with the criteria of the Third Adult Treatment Panel (ATP III). CRF was measured by peak oxygen uptake (VO2peak) assessed on a cycle ergometer via standardized cardiopulmonary exercise testing. RESULTS: Of all women (median age: 43 years), 57.9% had a previous diagnosis of breast cancer. The median time between diagnosis and study entry was 3 years (range: 0-32 years). Women fulfilling the criteria of metabolic syndrome had over 17 times higher odds of having increased AM levels compared to those who did not meet the criteria (OR = 17.49, p &amp;lt; 0.001). Moreover, high AM levels were associated with lower VO2peak (OR = 0.91, p &amp;lt; 0.001), higher BMI (OR = 1.24, p &amp;lt; 0.001) and higher circulating insulin levels (OR = 1.1, p &amp;lt; 0.001). AM levels were higher in women who have ever smoked (OR = 1.73, p = 0.022), and AM levels increased with the number of pack-years smoked (OR = 1.03, p = 0.06). AM levels were not associated with age (p = 0.143), BRCA mutation status (p = 0.51) or previous diagnosis of breast cancer (p = 0.48). After adjustment for confounding variables, we observed that MetS (OR = 10.78, p = 0.002) and VO2peak (OR = 0.92, p = 0.001) were independent determinants of circulating AM. CONCLUSIONS: This is the first study in BRCA mutation carriers that has linked circulating AM levels to MetS and CRF. The long-term clinical implications of these findings are yet to be determined. Conflict of interest: The study is funded by the German Cancer Aid (Deutsche Krebshilfe) within the Priority Program “Primary Prevention of Cancer” (Grant no. 110013). JS and OH are employed by Sphingotec GmbH, a company having patent rights in and commercializing the bio-ADM assay. SG and MK received grants from Sphingotec GmbH. JL, MYD, MB and MH have nothing to disclose. Citation Format: Jacqueline Lammert, Sabine Grill, Maryam Yahiaoui-Doktor, Maryam Basrai, Joachim Struck, Oliver Hartmann, Martin Halle, Marion Kiechle. High circulating levels of adrenomedullin are associated with metabolic syndrome and low cardiorespiratory fitness in BRCA1 and BRCA2 mutation carriers [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-10-16.