No abstract

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents, with highly aggressive behavior and early systemic metastasis. The survival rates for osteosarcoma remain unchanged over the past two decades. Studies aiming to find new or alternative therapies for patients with refractory osteosarcoma are urgently needed. Anlotinib, a novel multi‐targeted tyrosine kinase inhibitor (TKI), has exhibited encouraging clinical activity in NSLCC and soft tissue sarcoma, whereas its effect on osteosarcoma has not been studied. In our study, we investigated the anti‐tumor activity and underlying mechanism of anlotinib in osteosarcoma. Various in vitro and in vivo models of human osteosarcoma were used to determine the anti‐proliferative, anti‐angiogenesis and anti‐metastasis efficacy of anlotinib. Our results showed that anlotinib suppressed tumor growth and increased the chemo‐sensitivity of osteosarcoma. In addition, anlotinib inhibited migration and invasion in osteosarcoma cells. Furthermore, in order to explore the anti‐tumor mechanism of anlotinib, phospho‐RTK antibody arrays were performed. These analyses confirmed that anlotinib suppressed the phosphorylation of MET, VEGFR2 and the downstream signaling pathway activation. Moreover, we demonstrated that anlotinib blocked hepatocyte growth factor (HGF)‐induced cell migration, invasion and VEGF‐induced angiogenesis. Notably, a 143B‐Luc orthotopic osteosarcoma model further showed that anlotinib significantly inhibited growth and lung metastasis of implanted tumor cells. Our preclinical work indicates that anlotinib acts as a novel inhibitor of VEGFR2 and MET that blocks tumorigenesis in osteosarcoma, which could be translated into future clinical trials.

Dietary threonine imbalance is known to reduce the growth of the small intestine, liver, and skeletal muscle in young animals, but the underlying mechanism is largely unknown. Using the pig model, this study was conducted to test the hypothesis that either a deficiency or an excess of dietary threonine impairs protein synthesis in these tissues. Young pigs (25 d of age) were fed diets containing 0.37, 0.74 (current NRC requirement) or 1.11% true ileal digestible threonine (TIDT) (n = 6/diet). Pigs receiving the 0.74 and 1.11% TIDT diets were pair-fed with the same amount of feed as pigs receiving the 0.37% TIDT diet. After a 14-d dietary treatment, the fractional synthesis rate (FSR) of protein in tissues was measured using a flooding dose of l-phenylalanine plus L-[ring-(2)H(5)]phenylalanine. The results indicated that the FSR of protein in liver was reduced (P < 0.05) in pigs fed the 0.37% TIDT diet compared with pigs fed the 0.74 or 1.11% TIDT diet, and did not differ between pigs fed the 0.74 and 1.11% TIDT diets. The FSR of protein in longissimus muscle, jejunal mucosa, and mucins was reduced (P < 0.05) in pigs fed the 0.37 or 1.11% TIDT diet compared with pigs fed the 0.74% TIDT diet. The absolute synthesis rate of protein in the jejunal mucosa and muscle was also reduced (P < 0.01) in pigs fed the 0.37 and 1.11% TIDT diets compared with the controls. The absolute synthesis rate of hepatic protein was lower (P < 0.01) in pigs fed the 0.37% TIDT diets when compared with pigs fed the 0.74% TIDT diet. Protein synthesis in skeletal muscle as well as jejunal mucosa and mucins was reduced to a greater extent than that in liver in response to an imbalance of dietary threonine. Collectively, these results indicate that either an excess or a deficiency of dietary threonine decreases protein synthesis in rapidly growing tissues of young pigs. The findings provide a mechanism for the low growth performance of animals fed a threonine-imbalanced diet.