Chemotherapies such as doxorubicin are associated with cardiotoxicity. Follistatin-like 3 (FSTL3) has been shown to contribute to cardiac remodelling, and hypertrophy via activation of the TGF-β1-Smad 2/3 pathway. In this study, we evaluated the potential role of FSTL3 as an early biomarker and mediator of early onset chemotherapy-induced cardiomyopathy (CIC). The study is to elucidate the role of FSTL3 in doxorubicin induced cardiomyocyte injury.
The dose-response relationships for doxorubicin treatment (15.6 nM to 500μM) for 24 and 48 hours were evaluated in primary human cardiac myocytes. Extracellular and intracellular concentrations of FSTL3 were measured in cell supernatants and cell lysates, assayed by ELISA. Cell lysates were obtained for measurements of Smad2/3, and TGF-β1 via Western blot. Cardiomyocyte cytotoxicities were measured using Alamar Blue and lactate dehydrogenase (LDH) release. Doxorubicin dose-dependently induced cell mortality was significantly correlated with FSTL3 release (R=0.7, p=0.02) after 48 hours but not after 24 hours. There was also a significant relationship between extracellular and intracellular FSTL3 concentrations. There was a trend towards significant between increased intracellular FSTL3 and TGF-β1 expression but not with total Smad 2/3 ratio.
In this model, FSTL3 and TGF-β1 expressions appear synchronously with onset of doxorubicin- induced cardiotoxicity, suggesting that FSTL3 could play a role in doxorubicin-induced cardiotoxicity. Future studies manipulating FSTL3-mediated pathways are required to fully elucidate this mechanism.