Osteosarcoma is one of the most frequent types of primary malignant bone neoplasm in children and adolescents. Despite advancements developed in therapeutic modalities, the 5-year overall survival rates for patients with metastatic osteosarcoma disease remain poor. The present study aimed to investigate the expression level of microRNA-302a (miR-302a) in osteosarcoma tissues and cell lines, and the biological roles of miR-302a in osteosarcoma cells. In addition, the molecular mechanism underlying its tumor suppressive roles was evaluated. miR-302a expression in osteosarcoma tissues and cell lines was detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Following transfection of miR-302a mimics or IGF-1R siRNA, transwell migration and invasion, luciferase reporter assay RT-qPCR and western blot assays were conducted in osteosarcoma cells. In the present study, the data demonstrated that miR-302a was frequently reduced in osteosarcoma tissue and cell lines. In addition, the expression of miR-302a was correlated with metastatic features of patients with osteosarcoma. Restoration of miR-302a expression significantly inhibited the migration and invasion capacity of osteosarcoma cells. Mechanistic studies indicated that insulin-like growth factor 1 receptor (IGF-1R) was a direct target gene of miR-302a. Overexpression of miR-302a resulted in decreased expression of IGF-1R at the mRNA and protein levels. Furthermore, the knockdown IGF-1R mimicked the functions of miR-302a overexpression on osteosarcoma cell migration and invasion. Collectively, the results of the current study indicate that miR-302a acts as a metastasis suppressing miRNA and could be investigated as a therapeutic target for the treatment of patients with osteosarcoma to prevent metastasis.
Pleiotrophin (PTN) is a growth factor with both pro-angiogenic and limited pro-tumorigenic activity. We evaluated the potential for PTN to be used for safe angiogenic gene therapy using the full length gene and a truncated gene variant lacking the domain implicated in tumorigenesis. Mouse myoblasts were transduced to express full length or truncated PTN (PTN or T-PTN), along with a LacZ reporter gene, and injected into mouse limb muscle and myocardium. In cultured myoblasts, PTN was expressed and secreted via the Golgi apparatus, but T-PTN was not properly secreted. Nonetheless, no evidence of uncontrolled growth was observed in cells expressing either form of PTN. PTN gene delivery to myocardium, and non-ischemic skeletal muscle, did not result in a detectable change in vascularity or function. In ischemic hindlimb at 14 days post-implantation, intramuscular injection with PTN-expressing myoblasts led to a significant increase in skin perfusion and muscle arteriole density. We conclude that (1) delivery of the full length PTN gene to muscle can be accomplished without tumorigenesis, (2) the truncated PTN gene may be difficult to use in a gene therapy context due to inefficient secretion, (3) PTN gene delivery leads to functional benefit in the mouse acute ischemic hindlimb model.
Lysostaphin is widely used in clinical settings against Staphylococcus aureus, but its mutants can abolish its killing activity. The difficulty in studies of mutations in lysostaphin is the shortage of data, which may need many decades to collect, although lysostaphin is so important for clinical therapeutics and drug development. In order not to passively wait for the accumulation of new data, in this study 1) the 23,442 mutations in 1408 proteins from databank were used to determine whether the mutations in lysostaphin follow the general mutation trend obtained from the databank, 2) the amino-acid pair predictability was used to explore the underlined mechanism for lysostaphin mutations, and 3) the amino-acid distribution probability was used to associate the mutation with dysfunction of lysostaphin. The results show that the mutations in lysostaphin follow the general trend of mutations in proteins; the underlined mechanism for mutations in lysostaphin is explainable from a viewpoint of randomness, and a mutation with increased distribution probability would have a larger chance to dysfunction lysostaphin. This study provides useful information for future design of anti-S. aureus drug and enzyme engineering.
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