Search

MicroRNAs(miRNA) are noncoding RNAs of about 19-23 nucleotides that are crucial for many biological processes. Members of the microRNA-148/152(miR-148/152) family, which include microRNA-148a(miR-148a), microRNA-148b (miR-148b), and microRNA-152(miR-152), are expressed differently in tumor and nontumor tissues and are involved in the genesis and development of disease. Furthermore, members of the miR-148/152 family are important in the growth and development of normal tissues. Members of the miR-148/152 family regulate target genes and are regulated by methylation of CPG islands. In this review, we report recent studies on the expression of members of the miR-148/152 family, methylation of CPG islands, and their target genes in different diseases, as well as in normal tissues. [ABSTRACT FROM AUTHOR]

Background: MicroRNAs (miRNAs) are involved in cancer development and progression, acting as tumor suppressors or oncogenes. Our previous studies have revealed that miR-148a and miR-152 are significantly downregulated in gastrointestinal cancers. Interestingly, miR-148b has the same "seed sequences" as miR-148a and miR- 152. Although aberrant expression of miR-148b has been observed in several types of cancer, its pathophysiologic role and relevance to tumorigenesis are still largely unknown. The purpose of this study was to elucidate the molecular mechanisms by which miR-148b acts as a tumor suppressor in gastric cancer. Results: We showed significant down-regulation of miR-148b in 106 gastric cancer tissues and four gastric cancer cell lines, compared with their non-tumor counterparts by real-time RT-PCR. In situ hybridization of ten cases confirmed an overt decrease in the level of miR-148b in gastric cancer tissues. Moreover, the expression of miR- 148b was demonstrated to be associated with tumor size (P = 0.027) by a Mann-Whitney U test. We also found that miR-148b could inhibit cell proliferation in vitro by MTT assay, growth curves and an anchorage-independent growth assay in MGC-803, SGC-7901, BGC-823 and AGS cells. An experiment in nude mice revealed that miR-148b could suppress tumorigenicity in vivo. Using a luciferase activity assay and western blot, CCKBR was identified as a target of miR-148b in cells. Moreover, an obvious inverse correlation was observed between the expression of CCKBR protein and miR-148b in 49 pairs of tissues (P = 0.002, Spearman's correlation). Conclusions: These findings provide important evidence that miR-148b targets CCKBR and is significant in suppressing gastric cancer cell growth. Maybe miR-148b would become a potential biomarker and therapeutic target against gastric cancer. [ABSTRACT FROM AUTHOR]