Association of Genetic Variants at TRPC6 With Chemotherapy-Related Heart Failure

Abstract

Background: Our previous GWAS identified genetic variants at six novel loci that were associated with a decline in left ventricular ejection fraction (LVEF), p < 1 × 10 −5 in 1,191 early breast cancer patients from the N9831 clinical trial of chemotherapy plus trastuzumab. In this study we sought replication of these loci. Methods: We tested the top loci from the GWAS for association with chemotherapy-related heart failure (CRHF) using 26 CRHF cases from N9831 and 984 patients from the Mayo Clinic Biobank which included CRHF cases ( N = 12) and control groups of patients treated with anthracycline +/– trastuzumab without HF ( N = 282) and patients with HF that were never treated with anthracycline or trastuzumab ( N = 690). We further examined associated loci in the context of gene expression and rare coding variants using a TWAS approach in heart left ventricle and Sanger sequencing, respectively. Doxorubicin-induced apoptosis and cardiomyopathy was modeled in human iPSC-derived cardiomyocytes and endothelial cells and a mouse model, respectively, that were pre-treated with GsMTx-4, an inhibitor of TRPC6. Results: TRPC6 5 ′ flanking variant rs57242572-T was significantly more frequent in cases compared to controls, p = 0.031, and rs61918162-T showed a trend for association, p = 0.065. The rs61918162 T-allele was associated with higher TRPC6 expression in the heart left ventricle. We identified a single TRPC6 rare missense variant (rs767086724, N338S, prevalence 0.0025% in GnomAD) in one of 38 patients (2.6%) with CRHF. Pre-treatment of cardiomyocytes and endothelial cells with GsMTx4 significantly reduced doxorubicin-induced apoptosis. Similarly, mice treated with GsMTx4 had significantly improved doxorubicin-induced cardiac dysfunction. Conclusions: Genetic variants that are associated with increased TRPC6 expression in the heart and rare TRPC6 missense variants may be clinically useful as risk factors for CRHF. GsMTx-4 may be a cardioprotective agent in patients with TRPC6 risk variants. Replication of the genetic associations in larger well-characterized samples and functional studies are required.

Trpc6 Promotes Doxorubicin-Induced Cardiomyopathy in Male Mice With Pleiotropic Differences Between Males and Females

“…That study identified transient receptor potential cation channel subunit 6 ( TRPC6) as a potential risk locus for doxorubicin-induced cardiomyopathy in patients with breast cancer ( 19 ). In a follow-up study from our group using 984 patients from the Mayo Clinic Biobank, we replicated the association of toxicity, specifically with the outcome of doxorubicin-induced congestive heart failure (CHF) ( 20 ).…”

“…Breeding pairs of B6.129 wild-type (WT) (Cat#101045) and B6.129 Trpc6 whole body knock-out (KO) mice ( 26 ) (Cat#37345) were obtained from the Jackson Laboratory (Bar Harbor, ME). Male and female WT and Trpc6 KO mice (8–10 weeks old), ten mice per group, received either 100 μL intraperitoneally (ip) of control sterile saline or 4 mg/kg/dose doxorubicin for a cumulative dose of 24 mg/kg on days 1, 3, 5, 7, 9, 11 according to ( 20 ). Results were confirmed by repeating each experiment.…”

Inter-Individual Variation and Cardioprotection in Anthracycline-Induced Heart Failure

“…A subsequent study by the same group [ 50 ], replicated the association of TRPC6, this time using a case-control analysis with anthracycline-induced congestive heart failure as the outcome (Cases N = 38, Controls N = 984). In this study, the authors performed several levels of analyses which provided evidence for multiple risk variants at TRPC6, firstly suggesting that common non-coding variants within intron 1 and the 5’flanking region of TRPC6 increase risk of cardiotoxicity by their association with increased TRPC6 expression in heart tissue, and secondly that both common and rare missense variants at TRPC6 may increase risk of cardiotoxicity by gain-of-function.…”

“…The significance of these findings is that inhibition of TRPC6 may be a novel cardioprotective therapy, especially for individuals with TRPC6 risk variants. The therapeutic potential was validated in vitro, by demonstration that iPSC-derived cardiomyocytes were protected from doxorubicin-induced apoptosis by pre-treatment with the TRPC6 inhibitor, GsMT×4, and in vivo, by demonstration that GsMT×4 also protected mice from doxorubicin-induced decline in LVEF, global longitudinal strain and fibrosis [ 50 ].…”

“…A final point from the Norton study [ 50 ] especially highlights the need for mapping risk variants in different populations, but also to not rely completely on imputation for fine mapping of GWAS data. Sequencing of the 38 cases with doxorubicin-induced heart failure identified a very rare missense variant (N338S) in one of only four African-American individuals.…”