The Regulatory Role And Clinical Significance Of Y-BOX Binding Protein1(YB-1) In Human Osteosarcoma

Osteosarcoma is the most frequent bone malignancy in children and adolescents,comprising approximately1/5of all malignancies. To date, the underlyingmechanism of development and progession of osteosarcoma remain largely unknown.The aim of our study is to investigate the regulatory role of YB-1and discover thesignaling pathway that regulate expression of YB-1in osteosarcoma. All of ourstudies are aim to provide a new prognostic bio-marker and therapeutic candidatetarget for treating osteosarcoma.There is a significant correlation between YB-1level and histologic grade. Thepatients in the group of high YB-1expression and low expression are6cases (11.5%)and17cases (27%) of III grade,46cases (88.5%) and47cases (74.6%) of IV grade,respectively. The malignant degree of tumor was higher in the group of high YB-1expression than that of the group of low expression. The good CINR(chemotherapyinduced tumor necrosis rate, GR) in the both groups is42.3%(22cases),63.5%(40cases), and PR is57.7%(30cases) and36.5%(23cases), respectively. The datashowed that the patients with low YB-1expression have better response tochemotherapy (p=0.02). Furthermore, we found that the five-year survival rate in theboth groups was61.2%and76.6%(p=0.054), respectively; five-year no eventsurvival rate in the both groups was52.5%and72.4%(p=0.033), respectively, andthe transfer rate in in the both groups was41.8%and22.7%(95%CI:3.7%-37.3%),respectively. Moreover, tumor samples with high expression of YB-1showedupregulated levels of VEGF and CD31.These results suggested that there is a highpossibilty of tumor transfer and bad prognosis in the patients with high YB-1expression.The levels of YB-1mRNA and protein expression in high-migrated cellline(LM-7) were significantly higher than that of other cell lines. Furthermore, in the SaOS2cell line which has low migrated ability and low expression of YB-1,overexpression of YB-1by gene transfection significantly enhanced cell invasion andmigration. In contrast, in LM-7cell line, silence of YB-1by RNA interferencesignificantly suppressed cell invasion and migration. In vivo assay, we found thatSaOS2cell transfected with YB-1showed higher lung metastasis of tumor, and theability of lung metastasis of LM-7cell was downregulated after silence of YB-1.However, MTT and clone growth assay showed that YB-1could not affect cellproliferation and growth, which also was demonstrated by in vivo assay. In addition,we found that YB-1can reduce the cell response to cis-platinum treatment throughinhibition of cis-platinum-induced cell apoptosis. Furthermore, to investigate themechanism underlying by which YB-1regulated the osteosarcoma invasion,migration and chemotherapy-resistence, we performed human genome-wideexpression the analysis on osteosarcoma cell lines by HumanHT-12v4ExpressionBeadChip (Illumina). The results suggested that YB-1effect on osteosarcoma mightbe mediated by regulation of a series of genes, including TAT,VEGFA, MVP, et al.Through miRNA microarray analysis, we found that23miRNAs weresignificantly downregulated in the tumor samples with distant metatasis. We furtherfound that miR-382and miR-30d might act on the3’UTR site of YB-1throughbioinformatic analysis. Using luciferase report system, miR-382could directly bindthe3’UTR site of YB-1and regulate YB-1expression. Moreover, high level ofmiR-382was also detected in the in the tumor samples with distant metatasis, andthere is a significantly positive relationship between YB-1expression and tumormetatasis. In U20S cell line, we found that transfection of miR-382couldsignificantly reduce YB-1mRNA and protein expression, suppress cell invasion andmigration, and enhance sensitivity of cis-platinum chemotherapy. Through detectionof clinical tumor samples, we found that there is a negative correlation betweenmiR-382and YB-1levels.The clinical data showed that in the patients with high level of YB-1, the good CINR (chemotherapy induced tumor necrosis rate, GR) in endostar and controlgroups was71%(22cases) and42.3%(22cases), the poor CINR (PR) was29%(9cases) and57.7%(30cases), respectively, which suggested that the proportion ofpatient with GR in endostar group was significantly higher than that of control group(p<0.01). In the patients with low level of YB-1, the good CINR (chemotherapyinduced tumor necrosis rate, GR) in endostar and control groups was71.4%(25cases) and63.5%(40cases), the poor CINR (PR) was28.6%(10cases) and36.5%(23cases), respectively. There is no statistical difference between the both groups(P=0.43). Analysis of survival rate showed that in the patients with high level ofYB-1, the five-year overall survival rate in the both groups was76.7%and61.2%,respectively, which suggested that endostar chemotherapy could enhance five-yearoverall survival rate of patients, but showed no significant difference (p=0.081). Thefive-year no event survival rate in the both groups was71.1%and52.5%respectively,which suggested that endostar chemotherapy significantly enhanced the five-year noevent survival rate of patients (p=0.056). Moreover, endostar chemotherapysignificantly decreased the transfer rate of patients compared with control group, andthe transfer rate was22.7%and39.8%, respectively. However, in the patients withlow level of YB-1, there is no There is no statistical difference in five-year overallsurvival rate, five-year no event survival rate and transfer rate between endostarchemotherapy and control group.