Argonaute genes are essential for RNA interference, stem cell maintenance and differentiation. The Piwi-like genes, a subclass of the Argonaute genes, are expressed mainly in the germline. These genes may be re-expressed in tumors, and expression of the Piwi-like genes is associated with prognosis in several types of tumors.
We measured the expression of Piwi-like mRNAs (Piwi-like 2–4) in 125 soft tissue sarcoma (STS) samples by qPCRs. Statistical tests were applied to study the correlation of expression levels with tumor-specific survival for STS patients.
In multivariate Cox’s regression analyses, we showed that low Piwi-like 2 and Piwi-like 4 mRNA expression were significantly associated with a worse prognosis (RR=1.87; p=0.032 and RR=1.82; p=0.039). Low expression of both genes was associated with a 2.58-fold increased risk of tumor-related death (p=0.01). Piwi-like 4 and combined Piwi-like 2 and 4 mRNA levels correlated significantly with prognosis (RR=3.53; p=0.002 and RR=5.23; p=0.004) only for female but not for male patients. However, combined low Piwi-like 2 and 3 transcript levels were associated with worse survival (RR=5.90; p=0.02) for male patients.
In this study, we identified a significant association between the expression of Piwi-like 2 and 4 mRNAs and the tumor-specific survival of soft tissue sarcoma patients. Furthermore, a connection between sex and the impact of Piwi-like mRNA expressions on STS patients’ prognosis was shown for the first time.