Introduction: PIWI interacting RNAs (piRNAs) are endogenous regulatory non-coding RNAs which are generally expressed in the germline across animal species. The expressions of piRNAs in tumor tissue were rarely reported until now. The aim of this study was to investigate the expression of piRNAs in breast cancer.
Materials and methods: Deep sequencing was carried out in four tumor and four matched non-tumor tissues from resected breast cancer cases to screen out differentially expressed piRNAs. Furthermore, the result was evaluated by real-time reverse transcription-polymerase chain reaction (RT-PCR) technology in 50 patients with breast cancer and the piRNA expression levels were correlated with clinicopathologic features.
Results: Through deep sequencing, six differentially expressed piRNAs were screened out (5 up- and 1 down-regulated) in the four tumor tissues compared with matched non-tumor tissues. Among them, 4 piRNAs (piR-4987, piR-20365, piR-20485 and piR-20582) were confirmed to be up-regulated by realtime RT-PCR in 50 breast cancer (P < 0.001). Moreover, up-regulated piR-4987 expression was associated with lymph node positivity (P = 0.001).
Conclusions: PiRNAs might play a role in breast cancer and act as tumor markers.