Scientists from US have identified that hormone-related breast cancer and prostate cancer could specifically produce one kind of small RNAs which are originated from tRNAs. They play a very important role in promoting cell growth. This study was published in PNAS.

Transfer RNAs (tRNAs) are universally expressed in all three domains of life, and play a central role in protein synthesis as an adapter molecule translating codon triplet sequences into amino acids. Mature tRNAs are 70- to 90- nucleotides (nt) non-coding RNA molecules forming a cloverleaf secondary structure that further folds into a L-shaped tertiary structure. The human nuclear genome encodes over 500 tRNA genes over 500 tRNA genes, along with numerous genes of tRNA-lookalikes resembling nuclear and mitochondrial tRNAs.

Although transfer RNAs(tRNAs) are best known as adapter molecules essential for translation, recent biomedical and computational evidence has led to a previously unexpected conceptual consensus that tRNAs are not always end products but can further serve as a source of small functional RNAs, termed SHOT-RNAs, are specifically and abundantly expressed in sex hormone-dependent breast and prostate cancers. SHOT-RNAs are produced from aminoacylated mature tRNAs by angiogenin-mediated cleavage of the anticodon loop, which is promoted by sex hormones and their receptors.

In this study, researchers identified the complete repertoire of SHOT-RNAs, and also found their functional significance in cell proliferation. These results have unveiled a novel tRNA-engaged pathway in tumorigenesis.