THE ROLE OF piRNAs IN ONCOGENESIS: A REVIEW OF ASSOCIATIONS

Abstract

Background. The cumulation of data on molecular genetic events associated with oncogenesis resulted into transformation of the understanding of the role of small non-coding RNAs in the process. The largest class of these molecules is represented by piRNAs. In recent years, there has been a significant increase in the number of experimental studies uncovering functions of piRNAs, in particular, on their role in tumor cell transformation. This knowledge can be applied both in fundamental and practical oncology. Aim. To summarize data from published scientific papers on the association of piRNAs with human malignancies. Material and methods. The review represents analysis of studies on the effect of piRNAs on oncogenesis in humans. PubMed and eLIBRARY.RU databases were searched using the combinations of the terms («Carcinogenesis/Oncogenesis» OR «Cancer/Tumor») AND «piRNA», and the «Humans» as filter. Search was limited by the publication date until 01 January 2008. Results. 25 studies were included in the review. Among them with the aid of various molecular genetic methods ectopic levels of endogenous piRNAs expression were demonstrated in human tumor tissues or cell cultures, of which: for 36 piRNAs – increased, for 19 piRNAs – decreased, and for the piR-823 and piR-651 – aberrant multidirectional depending on one of nine tumor types. Modulation of piRNAs expression levels in many tumors was associated with changes in cell proliferation, apoptosis,tumor growth and metastasis, sensitivity to chemotherapeutic treatments, and other effects.Conclusion. Non-coding piRNAs play an important role in oncogenesis, determination of their level in tumors may have diagnostic or prognostic significance and modulation of the level of their expression may represent an effective antitumor therapeutic strategy