The Role of MicroRNAs in Lung Cancer / 中国肿瘤临床

ABSTRACT

MicroRNAs (miRNAs or miRs) are a class of small non-protein-coding RNAs, approximately 18 to 25 nt long. MicroRNAs can act as endogenous RNA interference. MicroRNAs can posttranscriptionally regulate the expression of hundreds of their target genes, controlling a wide range of biological functions such as cellular proliferation, differentiation, and apoptosis. MicroRNAs can posttranscdptionally regulate the expression of genes by hybridizing to complementary sequences in 3' UTR (3' untranslated region) of target messenger RNA (mRNA), repressing the translation of mRNA or increasing the instability of mRNA. A number of miRNAs are mapped to cancer-associated fragile regions (FRAs) as well as in minimal regions of loss of heterozygosity, minimal regions of amplification, or common breakpoint regions in the genome, suggesting that miRNAs might be involved in tumorigenesis. Many miRNAs are up or down-regulated in cancers as potential oncogene or tumor suppressors. It has been considered that the mutation of a series of oncogene or anti-oncogene gradually causes tumorigenesis. The conventional points of view were changed with the finding of non-protein-coding RNAs. MiRNA as members of non-protein-coding RNAs may play an important role in regulating tumor formation. Recent studies have in-vestigated the relationship of miRNAs with neoplasia, development, treatment and prognosis. Lung cancer is the leading cause of cancer-related deaths all over the world. Its etiology is primarily genetic and epigenetic damage caused by tobacco smoke. Systematic analysis of RNA and protein expression levels of thousands of genes has also contributed to defining the molecular net work of lung carcinogenesis. MiRNAs are closely related to lung cancer and play an important part in the diagnosis, therapy, surveillance and prognosis of lung cancer. We reviewed some miRNAs closely associated with lung cancer such as miRNA-126, miRNA-221, miRNA-222, has-mir-221, a polycistronic microRNA cluster miR-17-92, miRNA-128b, has-mir-137, has-mir-182, has-mir-372 and miRNA let-7. We summarized the roles of miRNAs in the genetic susceptibility, invasion or metastasis, diagnosis, therapy and prognosis of lung cancer.