目的:探讨人类染色体1p36等位基因杂合性缺失在小肝细胞癌(small hepatocellular carcinoma,sHCC)发生发展中的作用及其与临床病理表现的关系。方法:采用PCR-非变性聚丙烯酰胺凝胶电泳和硝酸银染色技术,对140例信息性sHCC中1p36上9个多态性微卫星标志位点的杂合性缺失(loss of heterozygosity,LOH)进行检测。结果:本组140例sHCCs发生LOH的总频率为65%(91/140),LOH以D1S507最高,为40.8%(31/76);在肿瘤直径≤1cm的HCC中,D1S507和D1S2893位点的LOH发生率显著高于直径>1cm组(P<0.05);在Edmondson分级≥Ⅲ级的HCC中,D1S468、D1S2694和D1S243位点LOH发生率明显高于≤Ⅱ级的HCC(P<0.05);包膜完整HCC中D1S243和RIZ位点的LOH发生率明显低于有包膜突破的HCC(P<0.05);女性患者中RIZ位点LOH发生率明显高于男性患者(P<0.05)。结论:sHCC在人染色体1p36上存在多个LOH位点,并与临床病理学参数之间有一定的相关性,提示这些缺失区可能存在候选肿瘤抑制基因,并与sHCC的发展和演进过程有关。
Aim： To characterize the matrix metalloproteinases （MMP）-2 promoter and to identify androgen response elements （AREs） involved in androgen-induced MMP-2 expression. Methods： MMP-2 mRNA levels was determined by reverse transcription-polymerase chain reaction （RT-PCR）. MMP-2 promoter-driven luciferase assays were used to determine the fragments responsible for androgen-induced activity. Chromatin-immunoprecipitation assay and electrophoretic mobility shift assays （EMSA） were used to verify the identified AREs in the MMP-2 promoter. Results： Androgen significantly induced MMP-2 expression at the mRNA level, which was blocked by the androgen antagonist bicalutamide. Deletion of a region encompassing base pairs -1591 to -1259 （relative to the start codon） of the MMP-2 promoter led to a significant loss of androgen-induced reporter activity. Additional deletion of the 5＇-region up to -562 bp further reduced the androgen-induced MMP-2 promoter activity. Sequence analysis of these two regions revealed two putative ARE motifs. Introducing mutations in the putative ARE motifs by site-directed mutagenesis approach resulted in a dramatic loss of androgen-induced MMP-2 promoter activity, indicating that the putative ARE motifs are required for androgen-stimulated MMP-2 expression. Most importantly, the androgen receptor （AR） interacted with both motif-containing promoter regions in vivo in a chromatin immunoprecipitation assay after androgen treatment. Furthermore, the AR specifically bound to the wild-type but not mutated ARE motifs-containing probes in an in vitro EMSA assay. Conclusion： Two ARE motifs were identified to be responsible for androgen-induced MMP-2 expression in prostate cancer cells.
