Regulation of osteoblast autophagy based on PI3K/AKT/mTOR signaling pathway study on the effect of β-ecdysterone on fracture healing

Abstract

Objectives To investigate the effects of β-ecdysterone on fracture healing and the underlying mechanism. Methods MTT assay was used to detect the cell viability. AO/PI and flow cytometry assays were used to determine the apoptotic rate. The expression level of RunX2, ATG7 and LC3 was evaluated by qRT-PCR and Western blot assays. X-ray and HE staining were conducted on the fractured femur. Immunohistochemical assay was used to detect the expression level of Beclin-1 and immunofluorescence assay was used to measure the expression level of LC3 in the fractured femurs. Western blot was utilized to determine the expression level of PI3K, p-AKT1, AKT1, p-mTOR, mTOR, p-p70S6K, and p70S6K. Results The ALP activity and the expression of RunX2 in fractured osteoblasts were significantly elevated, the apoptotic rate was suppressed by rapamycin, 60, and 80 μM β-ecdysterone. The state of autophagy both in fractured osteoblasts and femurs was facilitated by rapamycin and β-ecdysterone. Compared to control, Garrett score was significantly promoted in rapamycin and β-ecdysterone groups, accompanied by ameliorated pathological state. Lastly, the PI3K/AKT/mTOR pathway both in fractured osteoblasts and femurs was inhibited by rapamycin and β-ecdysterone. Conclusion β-ecdysterone might facilitate fracture healing by activating autophagy through suppressing PI3K/AKT/mTOR signal pathway.

An Injectable Sustained Release Hydrogel of Hyaluronic Acid Loaded with β‐Ecdysterone Ameliorates Cartilage Damage in Osteoarthritis via Activating Autophagy

“…[ 47 ] Previous research reported that β‐Ec promoted autophagy to improve fracture in rats. [ 48 ] This research proved that the signaling strength of PI3K/AKT/mTOR pathway is inhibited by β‐Ec, moreover, 3‐MA, the PI3K inhibitor, treatment on chondrocytes suggested that β‐Ec directly acts on the PI3K/AKT/mTOR signaling pathway to inhibit apoptosis by activating autophagy. In addition, a study reported that estrogen can activate mTOR via Rheb, [ 49 ] and β‐Ec is an estrogen analogue, suggesting that it may inhibit the PI3K/AKT/mTOR signaling pathway via Rheb.…”

Exploring the therapeutic potential of isoorientin in the treatment of osteoporosis: a study using network pharmacology and experimental validation

“…Firstly, we need to further investigate and expand on the relevant mechanisms. Second, previous studies have shown that the regulation of AKT1 also affects osteoblastogenesis (Mukherjee et al 2012 ; Tang et al 2021 ). Therefore, to determine whether ISO impacts osteoblast proliferation and differentiation, more experiments are needed to prove this hypothesis.…”

Autophagy: An important target for natural products in the treatment of bone metabolic diseases

“…However, there are focused research on medications, particularly those involving natural compounds, that monitor and target autophagy using fracture nonunion or delayed union models (only two items). β-Ecdysterone, a polyhydroxylated steroid hormone found mainly in Achyranthes bidentata and Cyanotis arachnoidea, activates autophagy by inhibiting PI3K/ Akt/mTOR signaling pathway in femoral tissue of rats with femoral fractures, promoting osteoblast differentiation and mineralization, inhibiting apoptosis, and accelerating fracture healing (Tang et al, 2021b). Similarly, curcumin-treated rat femur fracture osteoblasts exhibited rapid fracture healing and autophagy activation, whereas the rate of fracture healing was noticeably slowed in the presence of curcumin plus 3-MA (Figure 3).…”