<p>The emerging roles of PIWI-interacting RNA in human cancers</p>

Abstract

PIWI-interacting RNAs (piRNAs) are a type of non-coding RNAs that interact with PIWI proteins, which are members of the argonaute family. Originally described in the germline, piRNAs are also expressed in human somatic cells in a tissue-specific manner. piRNAs are involved in spermatogenesis, germ stem-cell maintenance, silencing of transposon, epigenetic and genomic regulation and rearrangement. A large number of studies have demonstrated that expression of piRNAs is involved in many kinds of disease, including cancer. Abnormal expression of piRNAs is emerging as a critical player in cancer cell proliferation, apoptosis, invasion, and migration in vitro and in vivo. Functionally, piRNAs maintain genomic integrity by repressing the mobilization of transposable elements, and regulate the expression of downstream target genes via transcriptional or post-transcriptional mechanisms. Furthermore, altered expression of piRNAs in cancer is linked to clinical outcome, highlighting the important role that they may play as novel diagnostic and prognostic biomarkers, and as therapeutic targets for cancer therapy. In this review, we focus on the biogenesis and the functional roles of piRNAs in cancers, discuss emerging insights into the roles of piRNAs in the occurrence, progression, and treatment of cancers, reveal various mechanisms underlying piRNAs-mediated gene regulation, and highlight their potential clinical utilities as biomarkers as well as potential targets for cancer treatment.

Endogenous Retroelements in Cancer: Molecular Roles and Clinical Approach

“…The deficient of the piRNA pathway causes overexpression of REs, significantly compromised genome structure and, invariably, germ cell death and sterility [58]. The aberrant expression of piRNAs has been reported in the development of cancer including the proliferation, apoptosis, metastasis, and invasion of cancer cells [62]. Moreover, the high expression of PIWI proteins has been documented in many cancer types, including gastric cancer, liver cancer, intestinal cancer, breast cancer, nonsmall cell lung cancer, bladder cancer, ovarian cancer, and melanoma and is furthermore associated with the aggressiveness of sarcomas, gliomas, and leukemia [61,63].…”

PIWI-interacting RNAs: new biomarkers for diagnosis and treatment of breast cancer

“…While the transcription of transposon-derived piRNAs occurs from both genomic strands, sense and antisense piRNAs can be generated. While the origin of mRNAderived piRNAs is the 3′ untranslated regions of mRNAs, the lncRNAs-derived piRNAs originate from the entire lncRNA transcript [40]. Unlike miRNAs and siRNAs which are dependent on RNAse III Dicer for their maturation, piRNA biogenesis is a Dicer-independent process [41,42].…”

Renal Cell Tumors: Uncovering the Biomarker Potential of ncRNAs

“…Concerning piRNAs, most are not complementary to putative target mRNAs, indicating that piRNAs may be involved in epigenetic regulation rather than post-transcriptional regulation, controlling a variety of biological processes and being also implicated in cancer development [49]. Several studies aimed to disclose their biological role in different cancer types [50], including RCC [51][52][53]. However, the specific molecular mechanism underlying piRNAs' deregulation in carcinogenesis is still poorly understood, and further investigation is needed.…”