Plasticizer Di-(2-ethylhexyl) Phthalate and Its Metabolite Mono(2-ethylhexyl) Phthalate Inhibit Myogenesis in Differentiating Mouse and Human Skeletal Muscle Cell Models

The relationship between plasticizer di(2-ethylhexyl) phthalate (DEHP) and low birth weight in neonates has been reported. Immature muscle differentiation may be involved in low birth weight. The myotoxic characteristics of chemicals have been observed in differentiating immortalized and primary muscle cells. Here, we explored the myotoxic effects of DEHP and its metabolite mono(2-ethylhexyl) phthalate (MEHP) in vitro using the immortalized mouse skeletal myoblasts C2C12 and primary human skeletal muscle progenitor cell (HSMPC) models. We found that both DEHP and MEHP at the concentrations of 10-100 mu M, which were non- and low-cytotoxicity concentrations, significantly and dose-dependently inhibited the creatine kinase activity, myotube formation with multiple nuclei, and myogenin and myosin heavy chain (muscle differentiation markers) protein expression in C2C12 and HSMPCs under differentiation medium. Both DEHP and MEHP significantly decreased Akt phosphorylation in C2C12 and HSMPCs during differentiation. Taken together, DEHP and its metabolite MEHP are capable of inhibiting Akt-regulated myogenesis in myoblasts/myogenic progenitors during differentiation. These findings suggest the possibility of DEHP as an environmental risk factor affecting skeletal myogenic differentiation. Moreover, these in vitro muscle cell models may be a possible alternative method to animal myotoxicity testing.