视网膜母细胞瘤高迁移率族蛋白A、MIB-1标记指数和let-7的表达及其相关性分析

摘要

目的 观察分析视网膜母细胞瘤(RB)肿瘤组织中高迁移率族蛋白A (HMGA)1和HMGA2、MIB-1标记指数(LI)及let-7的表达及其相关性.方法 44例RB肿瘤组织标本纳入研究.其中,低分化组织标本11例,高分化组织标本33例.侵袭性肿瘤组织标本8例,非侵袭性肿瘤组织标本36例.采用免疫组织化学染色方法检测RB肿瘤组织标本中HMGA1、HMGA2及MIB-1 LI的表达.HMGA1、HMGA2表达判定标准:以0为无表达,1％～10％为低度表达,11％～50％为中度表达,＞50％为高度表达；MIB-1 LI表达判定标准:以0为无表达,1％～40％为低度表达,＞40％为高度表达.采用逆转录聚合酶联反应检测let-7的表达；以≥80％为无明显下降,60％～79％为中度下降,＜60％为高度下降.结果 44例标本中,HMGA1无表达14例,占32％；低度表达11例,占25％；中度表达10例,占23％;高度表达9例,占20％.低分化组织标本的HMGA1表达率高于高分化组织标本,差异有统计学意义(x2=11.3,P＜0.01).侵袭性与非侵袭性肿瘤组织标本的HMGA1表达率比较,差异无统计学意义(x2=5.9,P＞0.05).HMGA2无表达11例,占25％；低度表达11例,占25％；中度表达9例,占20％；高度表达13例,占30％.低分化组织标本的HMGA2表达率高于高分化组织标本,差异有统计学意义(x2=20.9,P＜0.05).侵袭性肿瘤组织标本的HMGA2表达率高于非侵袭性肿瘤组织标本,差异有统计学意义(x2=8.7,P＜0.05).MIB-1 LI无表达4例,占9％；低度表达18例,占41％；高度表达22例,占50％.低分化组织标本的MIB-1 LI表达水平高于高分化组织标本,差异有统计学意义(t=5.2,P＜0.05).侵袭性肿瘤组织标本的MIB-1 LI表达水平高于非侵袭性肿瘤组织标本,但差异无统计学意义(t=-1.1,P＞0.05).let-7表达无明显下降27例,占61％,中度下降8例,占18％,高度下降9例,占21％.相关性分析结果显示,MIB-1 LI表达与HMGA1和HMGA2表达呈显著正相关(r=0.327、0.602,P＜0.05)；let-7表达与HMGA1、HMGA2表达及MIB-1 LI表达均呈负相关(r=-0.247、-0.310、-0.392,P＜0.05).结论 在RB肿瘤组织中HMGA1、HMGA2和MIB-1 LI均呈现高表达,let-7表达下降.let-7有可能抑制HMGA1和HMGA2的表达.%Objective To observe the expression and relationship of high-mobility group A(HMGA) 1,HMGA2,MIB-1 labeling index (LI) and let-7 in retinoblastoma (RB).Methods Forty-four RB samples were studied,including 11 poorly differentiated samples,33 well-differentiated samples; eight invasive and 36 non-invasive samples.The expression of HMGA1,HMGA2 and MIB-1 LI in RB were analyzed by immunohistochemitry.The HMGA1,HMGA2 were scored on a scale of 0 to high expression.0: no expression ; low: 1％ - 10 ％ ; medium: 11 ％ - 50 ％ ; high: ＞50 ％.The MIB LI were scored on a scale of 0to high expression.O: no expression;low: 1％ - 40％;high: ＞ 40％.Semiquantitative reverse transcription-polymerase chain reaction was used to assay the let-7 expression level: ≥ 80％ showed no significantly decreased expression; 60％ - 79％ showed medium decrease in expression; ＜ 60％ highly decreased in expression.Results In 44 RB samples,there were 14 cases with no HMGA1 expression (32％),11 cases with low expression (25％),10 cases with medium expression (23％),and nine cases with high expression (20％).Expression level of HMGA1 was significantly higher in poorly differentiated RB than in well-differentiated RB (x2 =11.3,P＜0.01) ; however,no statistically significant difference was found between invasive tumors and noninvasive tumors (x2 -5.9,P＞0.05).There were 11 cases with no HMGA2 expression (25％),11 cases with low expression-(25％),nine cases with medium expression (20％),and 13 cases with high expression (30％).Expression level of HMGA2 was significantly higher in poorly differentiated and invasive RB than in well differentiated and noninvasive RB respectively (x2=20.9,8.7; P＜0.05).There were 4 cases with no MIB-1 LI expression (9％),18 cases with low expression (41％),and 22 cases with high expression (50％).Expression level of MIB1 LI was significantly higher in poorly differentiated RB than in well-differentiated RB (t=5.2,P＜0.05).Higher expression of MIB-1 LI was found in invasive tumors than in noninvasive tumors,with no significant difference (t=-1.1,P＞0.05).Twenty seven cases had no significantly decreased expression of let-7 (61％).There were eight cases with medium decreased expression (18％) and nine cases with highly decreased expression (21％).Correlation analyses revealed that MIB1 LI expression significantly correlated with HMGA1and HMGA2 proteins (r=0.327,0.602; P＜0.05).A significantly inverse correlation existed between let-7 expression and HMGA1,HMGA2 proteins and MIB-1LI respectively (r=-0.247,-0.310,-0.392; P＜0.05).Conclusions Overexpression of HMGA1,HMGA2 and MIB-1 LI and down regulation of let-7 were demonstrated in RB.Supplying let-7 to RB cells can possibly inhibit HMGA1 and HMGA2 expression.