Downregulated lncRNA GAS5 and Upregulated miR-21 Lead to Epithelial-Mesenchymal Transition and Lung Metastasis of Osteosarcomas.

Lung is the primary site of osteosarcoma metastasis, but the underlying genetic or epigenetic factors determining lung metastasis of osteosarcoma are unknown. In this study, we report the status of growth arrest specific 5 (GAS5) in lung metastatic osteosarcomas. GAS5 was generally downregulated in osteosarcoma patients (n = 24) compared to healthy controls (n = 10) and even more so in patients with lung metastatic disease(n = 11) compared to the patients without metastasis (n = 13). We also report a role of miR-21 in GAS5-mediated effects. Downregulation of GAS5 in hFOB 1.19 and U2OS osteosarcoma cells enhanced their migration and invasion, along with an upregulated epithelial-mesenchymal transition (EMT), as evidenced by downregulated E-cadherin and upregulated vimentin, ZEB1, and ZEB2. Downregulation of GAS5 also resulted in a significantly increased expression of miR-21. Moreover, downregulation of such elevated miR-21 was found to reverse the effects of GAS5 silencing. miR-21 was also found to be elevated in osteosarcoma patients with its levels particularly high in patients with lung metastasis. Our observations reveal a possible role of GAS5 and miR-21 in lung metastasis of osteosarcoma, presenting them as novel targets for therapy.

A multiple drug loaded, functionalized pH-sensitive nanocarrier as therapeutic and epigenetic modulator for osteosarcoma.

Osteosarcoma is a malignant condition affecting adolescents and children more than adults. Nanobiomedicine has opened up several avenues which have increased therapeutic efficiencies than the conventional treatment for the same. In the current study, a novel organic nanoparticle was devised conjugated with bisphosphonate zoledronic acid which has an affinity for bone tissues. Moreover, the nanoparticle was loaded with multiple anti-cancer drugs like gemcitabine and epirubicin. The nanoparticles were characterized by microscopic analysis, entrapment and loading efficiencies, bone affinity studies, in-vitro release studies, cytotoxicity studies and finally in-vivo tumor regression studies. Bone affinity studies depicted a high affinity of zoledronic acid towards bone powder. The nanoparticle exhibited a nanosize dimension, high entrapment and loading efficiencies with uniform symmetry devoid of agglomeration. The in-vitro release experiments showed a measured release of drugs over a longer time without any hint of burst release. However, the release was comparatively for a longer duration in acidic pH and normal physiological pH which may be excellent for therapeutic efficiency. The cytotoxicity studies revealed enhanced cytotoxic effect for MG-63 cell lines in comparison of free drug or single drug combinations. Nonetheless, they proved to be cytocompatible with primary bone cells. Additionally, cellular uptake of nanoparticle was appreciably improved. Significant tumor (250%) regression was seen upon treatment with multiple drug loaded zoledronic acid conjugated nanoparticle, along with epigenetic changes affecting microRNA expressions. The increased cytotoxicity and increased cellular uptake may be of greater advantage in systemic osteosarcoma therapy. Combining all results, our study demonstrated substantial potential towards management of osteosarcoma.