Low-Concentration Arsenic Trioxide Inhibits Skeletal Myoblast Cell Proliferation via a Reactive Oxygen Species-Independent Pathway

Abstract

Myoblast proliferation and differentiation are essential for skeletal muscle regeneration. Myoblast proliferation is a critical step in the growth and maintenance of skeletal muscle. The precise action of inorganic arsenic on myoblast growth has not been investigated. Here, we investigated the in vitro effect of inorganic arsenic trioxide (As2O3) on the growth of C2C12 myoblasts. As2O3 decreased myoblast growth at submicromolar concentrations (0.25–1 μM) after 72 h of treatment. Submicromolar concentrations of As2O3 did not induce the myoblast apoptosis. Low-concentration As2O3 (0.5 and 1 μM) significantly suppressed the myoblast cell proliferative activity, which was accompanied by a small proportion of bromodeoxyuridine (BrdU) incorporation and decreased proliferating cell nuclear antigen (PCNA) protein expression. As2O3 (0.5 and 1 μM) increased the intracellular arsenic content but did not affect the reactive oxygen species (ROS) levels in the myoblasts. Cell cycle analysis indicated that low-concentrations of As2O3 inhibited cell proliferation via cell cycle arrest in the G1 and G2/M phases. As2O3 also decreased the protein expressions of cyclin D1, cyclin E, cyclin B1, cyclin-dependent kinase (CDK) 2, and CDK4, but did not affect the protein expressions of p21 and p27. Furthermore, As2O3 inhibited the phosphorylation of Akt. Insulin-like growth factor-1 significantly reversed the inhibitory effect of As2O3 on Akt phosphorylation and cell proliferation in the myoblasts. These results suggest that submicromolar concentrations of As2O3 alter cell cycle progression and reduce myoblast proliferation, at least in part, through a ROS-independent Akt inhibition pathway.

Arsenic trioxide inhibits the functions of lung fibroblasts derived from patients with idiopathic pulmonary fibrosis

“…These findings suggest that ATO does not alter DNA synthesis but rather prevents the entry of HLFs into mitosis. ATO is known to disturb the cell cycle by modulating the expression of cyclin and CDK (Liu et al, 2015;Park et al, 2001;Su et al, 2015;Zhao et al, 2002). In HLF ATO did not alter the concentration of cyclin-D1, which controls the G0 to G1 progression, but it decreased the concentrations of cyclin-A, cyclin-B and CDK2, all key regulators of the G2/M phase transition, so retarding mitosis.…”

Embryonic-only arsenic exposure alters skeletal muscle satellite cell function in killifish (Fundulus heteroclitus)

“…Similar results were seen in C2C12 myoblasts, where arsenic exposure significantly impaired myotube formation (Yen et al, 2010). Further, PCNA protein expression in C2C12 myoblasts was significantly reduced after exposure to low-dose arsenic, indicating a reduction in proliferation (Liu et al, 2015). The results of all of these studies indicate that arsenic can impair skeletal muscle proliferation and differentiation.…”

“…Similar cardiotoxin injury and regeneration studies have been done in mice, where recovery and muscle regeneration was assessed between 2 and 14 days post-injury based on satellite cell activation (Yen et al, 2010; Mahdy et al, 2015; Hardy et al, 2016). Lower PCNA expression can be associated with reduced proliferation of muscle satellite cells, which would then lead to an impaired ability to recover after an injury (Liu et al, 2015; Dumont et al, 2015).…”

In Vitro Cytotoxic and Anticancer Effects of Zamzam Water in Human Lung Cancer (A594) Cell Line

“…It is well known that cyclin D1 and cyclin E are regulatory proteins that control the transition from G1 to S phase, whereas, cyclin B1 regulates the progression of the G2/M phase. Recently, a study reported that a lowconcentration of inorganic arsenic inhibits the proliferation of C 2 C1 2 myoblasts cells by inducing G1 and G2/M phase cell-cycle arrest due to the decrease in the protein expressions of cyclin D1, cyclin E, and cyclin B1 (26). In this study, it was assumed that the arresting effect of Z1 and Z2 in A549 cells might be due to the decreased levels of cyclin D1, cyclin E, and cyclin B1 caused by both the effect of both the alkaline pH and the elements found naturally in Zamzam water.…”