piRNA, the new non-coding RNA, is aberrantly expressed in human cancer cells

Background: Piwi-interacting RNAs (piRNAs) are a novel class of non-coding single strand RNAs. They are involved in germline development, in silencing of selfish DNA elements, and in maintaining germline DNA integrity. The relationship between piRNAs and carcinogenesis has not been shown yet. Methods: The relationship between piRNAs and carcinogenesis was identified by microarray screening and real-time quantitative reverse transcription-polymerase chain reaction technology. The piR-651 inhibitor was transfected into gastric cancer cells to assess its influence on cell growth. Cell cycle analysis was used to reveal the cellular mechanisms of piR-651 in the genesis of gastric cancer. Results: piR-651 expression was upregulated in gastric cancer tissues compared with paired non-cancerous tissues. The levels of piR-651 were associated with TNM stage (P = 0.032). The expression of piR-651 in gastric, colon, lung, and breast cancer tissues was higher than that in paired non-cancerous tissues. The upregulated expression of piR-651 was confirmed in several cancer cell lines including gastric, lung, mesothelium, breast, liver, and cervical cancer cell lines. The growth of gastric cancer cells was inhibited by a piR-651 inhibitor and arrested at the G(2)/M phase. Conclusion: piR-651 might be involved in the development of gastric cancer and other cancers, and is a potential marker for cancer diagnosis. (C) 2011 Elsevier B.V. All rights reserved.