Long non-coding RNA PVT1 promotes osteosarcoma development by acting as a molecular sponge to regulate miR-195.

A growing body of evidence has indicated that long non-coding RNAs (lncRNAs) serve as competing endogenous RNAs (ceRNAs) during oncogenesis. In this study, the qRT-PCR results indicated that the lncRNA PVT1 is overexpressed in osteosarcoma and decreased the survival rate of osteosarcoma patients. MTT and clonal colony formation assays were used to detect the effect of PVT1 on proliferation, and flow cytometry was performed to assess apoptosis and the cell cycle. A Transwell assay was used to analyze migration and invasion. The results revealed that silencing PVT1 by siRNA inhibited proliferation, migration and invasion and promoted apoptosis and cell cycle arrest in osteosarcoma cells. Furthermore, a gene microarray was used to screen differentially expressed miRNAs associated with PVT1. The interaction between PVT1 and miRNAs was then analyzed by qRT-PCR and luciferase reporter gene assay. We found that PVT1 negatively regulated miR-195 in osteosarcoma cells. Simultaneously, we found that silencing PVT1 by siRNA suppressed proliferation, migration and invasion and promoted cell cycle arrest and apoptosis via miR-195 in osteosarcoma cells. Moreover, silencing PVT1 by siRNA inhibited BCL2, CCND1, and FASN protein expression via miR-195 in osteosarcoma cells, and BCL2 inhibited the si-PVT1#1-induced apoptosis of U2OS cells. CCND1 inhibited the cell cycle arrest of U2OS cells induced by si-PVT1#1. FASN promoted the invasiveness U2OS cells, which was inhibited by si-PVT1#1. Therefore, our study demonstrated that PVT1 may be a therapeutic target for treatment of osteosarcoma.

B7-H3 protein expression in a murine model of osteosarcoma.

Osteosarcoma is an aggressive type of bone tumor that commonly occurs in pediatric age groups. The complete molecular mechanisms behind osteosarcoma formation and progression require elucidation. B7-H3 is a protein of the B7 family that acts as a co-stimulatory molecule with a significant role in adaptive immune responses. The link between B7-H3 expression and its role in different types of cancer remains unclear. B7-H3 protein exhibits different functional roles in in vivo and in vitro conditions that remain controversial. In the present study, a murine model of osteosarcoma was successfully established using a modified protocol so as to easily obtain a low grade and metastatic form of osteosarcoma tissue without complication. Histological data showed that a less organized and highly proliferative mass of cells was observed in the osteosarcoma tissue. A higher expression level of B7-H3 protein was also observed at each advanced stage of osteosarcoma, which indicated the contributory role of the protein in the development of the primary and metastatic forms of osteosarcoma. Immunohistochemistry was performed, which showed that the overexpression of B7-H3 protein in the metastatic form of osteosarcoma may be associated with its migration and invasion.

Downregulation of CD99 and upregulation of human leukocyte antigen class II promote tumor aggravation and poor survival in patients with osteosarcomas.

BACKGROUND: CD99 is involved in the intracellular transport of human leukocyte antigen class II (HLA-II) protein. The aim of this study was to clarify the clinical value of CD99 and HLA-II expression in primary osteosarcoma. METHODS: One hundred and thirty pairs of osteosarcoma and matched noncancerous bone tissues were evaluated by immunohistochemistry for CD99 and HLA-II expression. RESULTS: Compared with the noncancerous bone tissues, the expression levels of CD99 (tumor versus normal: 2.96±0.09 versus 5.89±1.26, P<0.001) and HLA-II (tumor versus normal: 5.01±1.39 versus 1.92±0.06, P<0.001) proteins were respectively downregulated and upregulated in osteosarcoma tissues. CD99 and HLA-II were highly expressed in 49/130 (37.69%) and 107/130 (82.31%) of osteosarcoma tissues, respectively. In addition, the osteosarcoma patients with downregulation of CD99 and upregulation of HLA-II more frequently showed the presence of metastasis and recurrence and poor response to chemotherapy. Moreover, there was a negative correlation between CD99 and HLA-II expression in osteosarcoma tissues (r=-0.69, P=0.01). The patients with low CD99 expression correlated with poor prognosis of osteosarcoma, as opposed to HLA-II. Patients with CD99-low/HLA-II-high expression had the lowest overall and disease-free survival rates, and conjoined expression of CD99/HLA-II was an independent prognostic indicator of osteosarcoma. CONCLUSION: These findings suggest for the first time that CD99 downregulation or HLA-II upregulation may be an important feature of human osteosarcoma. The combined detection of CD99/HLA-II coexpression may present a predictive and prognostic indicator in osteosarcoma.

VEGF and EMMPRIN expression correlates with survival of patients with osteosarcoma.

AIM: To investigate the clinicopathologic characteristics of Vascular Endothelial Growth Factor (VEGF) and Extracellular Matrix Metalloproteinase Inducer (EMMPRIN) expression in osteosarcoma, and to evaluate the clinical significance of these two markers in the survival of osteosarcoma. METHODS: VEGF and EMMPRIN expression in paraffin-embedded specimens gathered from 65 patients with primary osteosarcoma were detected by the method of immunohistochemistry using antibodies against VEGF and EMMPRIN. The correlation of VEGF and EMMPRIN expression with the clinicopathologic features and with the survival of osteosarcoma was subsequently assessed. RESULTS: The expression of VEGF and EMMPRIN was detected in 47/65 (72.31%) and 45/65 (69.23%) of patients with osteosarcoma, respectively. Positive expression of VEGF and EMMPRIN was significantly correlated with surgical stage and percentage of dead cells of osteosarcoma. A significant correlation was found between the expression of VEGF and EMMPRIN in osteosarcoma (r=0.89, p=0.01). Additionally, surgical stage, percentage of dead cells, VEGF and EMMPRIN expression showed significant influence on overall survival (OS) and disease-free survival (DFS) in univariate analysis. In multivariate analysis, surgical stage (IIA versus IIB/III) and percentage of dead cells (≤90% versus >90%) were significant for DFS and OS. Those patients with VEGF+/EMMPRIN+ co-expression showed significantly shorter OS and DFS compared with VEGF-/EMMPRIN- expression. CONCLUSION: According to our study, the overexpression of VEGF or EMMPRIN may be an important feature of osteosarcoma. A combined detection of VEGF/EMMPRIN co-expression may benefit us in prediction of a poor survival of osteosarcoma.

mTOR/p70S6K signal transduction pathway contributes to osteosarcoma progression and patients' prognosis.

The mTOR/p70S6K signal transduction pathway plays a key role in the regulation of cancer cells' survival and proliferation. However, its roles in osteosarcoma, which is one of the most rapidly growing sarcomas, remain unknown. This study investigated for the first time the correlation between the mTOR/p70S6K signal transduction pathway in human osteosarcoma and patients' prognosis. The expression patterns of mTOR and p70S6K in paraffin-embedded specimens gathered from 65 patients with primary osteosarcoma were detected by the method of immunohistochemistry using antibodies against mTOR and p70S6K. Kaplan-Meier survival and Cox regression analyses were performed to evaluate the prognosis of patients. Immunostaining revealed that the mTOR/p70S6K signal transduction pathway is activated in human osteosarcoma. Additionally, positive expression of mTOR and p70S6K proteins was significantly correlated with surgical stage, metastasis pattern and percentage of dead cells of osteosarcoma. Moreover, in univariate analysis, surgical stage, metastasis pattern and percentage of dead cells, mTOR and p70S6K expression showed significant influence on overall survival (OS) and disease-free survival (DFS). In multivariate analysis, surgical stage (IIA vs. IIB/III), metastasis pattern (without vs. with), percentage of dead cells (≥90 vs. <90%), mTOR expression pattern (negative vs. positive) and p70S6K expression pattern (negative vs. positive) were significant for DFS and OS. Our results demonstrate the correlation of mTOR and p70S6K expression patterns with the oncological progression of osteosarcoma patients, suggesting the prognostic significance of the mTOR/p70S6K signal transduction pathway in osteosarcoma patients, which may lay a foundation for making further investigations on the mTOR/p70S6K signal transduction pathway as a potential target for osteosarcoma therapy.