中文摘要：

微RNA（microRNA）-221和microRNA-222是成簇的microRNA，在恶性肿瘤中起促癌作用，在胶质母细胞瘤、前列腺癌、乳头状甲状腺癌等恶性肿瘤中高表达。microRNA-221和microRNA-222通过调控其特定的靶基因行使促癌作用。在所有预测的靶基因中，p27^kip1和p57^kip2是已被验证的靶基因，microRNA-221和microRNA-222通过下调p27^kip1和p57kip2的表达来促进肿瘤的形成和生长。

英文摘要：

It has become dear that particular microRNAs（miRNAs） function either as tumor suppressors or oncogenes, whose loss or overexpression, respectively, has diagnostic and prognostic significance. MicroRNA-221 and microRNA-222 are a cluster microRNAs of oncogenes. They are overexpressed in some malig- nant tumors, including glioblstoma, prostate carcinoma, papillary thyroid carcinoma, and so on. By regulating particular target mRNAs, microRNA-221 and microRNA-222 perform prooncogenic role. p27kip1 and p57kip2 are target genes of microRNA-221 and microRNA-222. MicroRNA-221 and microRNA-222 promote oncogensis and tumor grow by down-regulating p27 kipl and p57kip2 expression.