Biological concepts and potential clinical implications of piRNA in cancer

Introduction: PIWI-interacting RNAs (piRNAs) are small non-coding RNAs with 24-35 nucleotides in length that were first identified in Drosophila testis. The similarity of piRNAs to other small non-coding RNAs, such as miRNA and siRNA, is that they all interact with members of a similar family of Argonaute proteins and have a regulatory role in gene expression, But the biogenesis pathway of piRNAs differs from the other two small non-coding RNAs. In the human genome, there are more than 20000 piRNAs that play important role in regulating gene expression. Many studies have shown the aberrant expression of piRNAs as a unique feature in different types of cancer.Description: Cancer is the second leading cause of death in the world that treatment available for it are often ineffective and have high rates of recurrence and metastasis, so we need new biomarkers to diagnose and treat cancer. The RNA sequencing technique shows that piRNA have aberrant expression in different cancers, so they can be used as biomarkers to diagnose different types of cancer, including breast cancer, gastric cancer, lung cancer and more, in which the article is reviewed.Discussion and conclusion: In recent years, with the development of next-generation sequencing technology, we have been able to compare the expression level of different small non-coding RNAs, including piRNAs, between normal and cancerous cells. Recently, many piRNAs have been shown to be highly expressed in blood samples, so they can be used as biomarkers for cancer detection without the need for invasive procedures. However, further research is needed to understand the molecular mechanism of piRNAs and its clinical applications.