转录因子HBP1抑制骨肉瘤细胞增殖

Transcriptional Factor HBP1 Inhibits Growth in Osteosarcoma Cells

转录因子HBP1(HMG-box containing protein 1,HBP1)属HMG家族,是1个含有513个氨基酸残基的多肽,可与RB蛋白结合,抑制许多癌基因的表达,从而抑制细胞的增殖.本工作构建了HBP1慢病毒表达载体,病毒包装后感染骨肉瘤细胞U2OS细胞.Western印迹结果显示,感染细胞cyclin D1、c-Myc蛋白质水平降低,而p53蛋白质水平增加;Real-time PCR检测cyclin D1、c-Myc及p53 mRNA水平与蛋白质检测结果一致.HBP1表达载体(pEFBOS-HBP1)和报告基因载体(含cyclin D1、c-Myc或p53 promoter)共转染U2OS细胞后的荧光素酶分析发现,HBP1可抑制cyclinD1、c-Myc启动子转录激活,促进p53启动子转录激活,并且这种抑制或激活作用具有HBP1剂量依赖性.以细胞代龄群体倍增值PD(population doubling)为指标测试细胞生长结合软琼脂集落形成实验证明,HBP1慢病毒感染的U2OS细胞生长速度减缓、集落形成能力下降.上述结果提示,HBP1可能通过调控细胞增殖相关基因的表达抑制骨肉瘤细胞的增殖.

HBP1（HMG-box containing protein 1） is homologous to the sequence-specific high mobility group（HMG） family of transcriptional factors.It is comprised of 513 amino acid residues in overall histocytes.We have previously isolated HBP1 as a retinoblastoma（Rb） partner and have determined that it functions as a proliferation regulator by inhibiting oncogenic pathways as a transcriptional repressor.This study constructed HBP1 expression vector（lentivirus）,and infected osteosarcoma cells with the lentivirus vector to test the effect of HBP1 on the growth of the cells.Western blotting showed that the protein levels of cyclin D1 and c-Myc were decreased and p53 level increased after HBP1 transfection.The results were consistent with mRNA levels of cyclin D1,c-myc and p53 assayed by real-time PCR.After cells cotransfected with HBP1 expression vector pEFBOS-HBP1 and reporter vector,the luciferase assay indicated that HBP1 inhibits cyclin D1 and c-Myc promoter,but enhances p53 promoter.The effect of HBP1 on the promoters was dose-dependent.In addition,the growth rate and ability of growth in soft agar of the HBP1-transfected cells were suppressed through growth curve test（population doubling as index） and soft agar assay.The results indicated that transcription factor HBP1 inhibited the growth of osteosarcoma cells through regulating expression of proliferation associated genes.