Role Of piRNAs Research Articles

PIWI-Interacting RNAs: A Pivotal Regulator in Neurological Development and Disease.

PIWI-interacting RNAs (piRNAs), a class of small non-coding RNAs (sncRNAs) with 24-32 nucleotides (nt), were initially identified in the reproductive system. Unlike microRNAs (miRNAs) or small interfering RNAs (siRNAs), piRNAs normally guide P-element-induced wimpy testis protein (PIWI) families to slice extensively complementary transposon transcripts without the seed pairing. Numerous studies have shown that piRNAs are abundantly expressed in the brain, and many of them are aberrantly regulated in central neural system (CNS) disorders. However, the role of piRNAs in the related developmental and pathological processes is unclear. The elucidation of piRNAs/PIWI would greatly improve the understanding of CNS development and ultimately lead to novel strategies to treat neural diseases. In this review, we summarized the relevant structure, properties, and databases of piRNAs and their functional roles in neural development and degenerative disorders. We hope that future studies of these piRNAs will facilitate the development of RNA-based therapeutics for CNS disorders.

PIWI-RNAs Small Noncoding RNAs with Smart Functions: Potential Theranostic Applications in Cancer.

P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are a new class of small noncoding RNAs (ncRNAs) that bind components of the PIWI protein family. piRNAs are specifically expressed in different human tissues and regulate important signaling pathways. Aberrant expressions of piRNAs and PIWI proteins have been associated with tumorigenesis and cancer progression. Recent studies reported that piRNAs are contained in extracellular vesicles (EVs), nanosized lipid particles, with key roles in cell-cell communication. EVs contain several bioactive molecules, such as proteins, lipids, and nucleic acids, including emerging ncRNAs. EVs are one of the components of liquid biopsy (LB) a non-invasive method for detecting specific molecular biomarkers in liquid samples. LB could become a crucial tool for cancer diagnosis with piRNAs as biomarkers in a precision oncology approach. This review summarizes the current findings on the roles of piRNAs in different cancer types, focusing on potential theranostic applications of piRNAs contained in EVs (EV-piRNAs). Their roles as non-invasive diagnostic and prognostic biomarkers and as new therapeutic options have been also discussed.

Abstract 11989: PiRNA Mined From Therapeutic Cell Extracellular Vesicles, Protects Cardiac Tissue Post-Injury Through Epigenetic Silencing of Pick1 in Circulating Macrophages

Introduction: Small non-coding RNAs (snRNAs) comprise the majority of extracellular vesicle (EV) cargo. Therapeutic cells secrete EVs replete with snRNAs that repair damaged tissue through gene regulation in target cells. Piwi RNAs (piRNAs) are the most diverse class of snRNAs and a major component of EVs (called IMEX) secreted by engineered cardiosphere-derived cells. While much is known about the role of piRNAs in germline cells, little is known about their mechanism in tissue repair. Here we investigate the role of an enriched piRNA (piR-33044, we dub TEP3.4) in cardioprotection. Methods: W e used ischemia/reperfusion (I/R) injury in rats to evaluate the cardioprotective effect of TEP3.4. To identify a target cell type, we exposed bone-marrow-derived macrophages (BMDMs), cardiac fibroblasts, and cardiomyocytes to TEP3.4 to assess transcriptomic changes. To identify the gene target of TEP3.4, we performed whole-genome bisulfite sequencing (WGBS) and methylation-specific sequencing. Finally, to evaluate the role of macrophages in TEP3.4 cardioprotection, we adoptively transferred BMDMs exposed to TEP3.4 in I/R injury. Results: In vivo , TEP3.4 reduced infarct size (TEP3.4: 3.45±0.43g vs vehicle: 11.41±1.32g or scramble: 11.88±2.44g) and circulating cardiac troponin I (TEP3.4: 5.79±0.83ng/ml vs vehicle: 19.16±2.81ng/ml or scramble: 17.42±2.07ng/ml). BMDMs showed more transcriptomic changes compared to cardiac fibroblasts or cardiomyocytes (5435 genes vs 4114 and 2653, respectively). Methylation analysis identified pick1 as a target of TEP3.4. Pick1 downregulation enhanced Smad3 phosphorylation and phagocytic capacity in BMDMs. In vivo, Adoptive transfer of BMDMs exposed to TEP3.4 or pick1 silencing reduced infarct size (TEP3.4: 6.55± 0.85g vs vehicle: 16.73±2.13 or scramble: 16.15±3.43g in scramble) and cardiac troponin I (TEP3.4: 7.62 ±0.83ng/ml vs vehicle: 13.27 ±3.09ng/ml or scramble:15.24 ±4.04ng/ml). Conclusions: TEP3.4 exerts cardioprotection through methylation of pick1 and enhances phagocytosis in infiltrating macrophages. Pick1 downregulation in macrophages enhances phagocytosis and potentiates tissue healing and repair.

Expression of Extracellular Vesicle PIWI-Interacting RNAs Throughout hiPSC-Cardiomyocyte Differentiation.

Extracellular Vesicles (EV) play a critical role in the regulation of regenerative processes in wounded tissues by mediating cell-to-cell communication. Multiple RNA species have been identified in EV, although their function still lacks understanding. We previously characterized the miRNA content of EV secreted over hiPSC-cardiomyocyte differentiation and found a distinct miRNA expression in hiPSC-EV driving its in vitro bioactivity. In this work, we investigated the piRNA profiles of EV derived from key stages of the hiPSC-CM differentiation and maturation, i.e., from hiPSC (hiPSC-EV), cardiac progenitors (CPC-EV), immature (CMi-EV), and mature (CMm-EV) cardiomyocytes, demonstrating that EV-piRNA expression differs greatly from the miRNA profiles we previously identified. Only four piRNA were significantly deregulated in EV, one in hiPSC-EV, and three in CPC-EV, as determined by differential expression analysis on small RNA-seq data. Our results provide a valuable source of information for further studies aiming at defining the role of piRNA in the bioactivity and therapeutic potential of EV.

PiRNAs and PIWI proteins as potential biomarkers in ‌Breast cancer.

PIWI interacting RNAs (piRNAs) are another subgroup of small non-coding RNAs, that can play different biological activity further to their capabilities in the germline such as regulating the gene and protein expression, epigenetic silencing of transposable elements, and regulating the spermatogenesis by interacting with PIWI proteins. We search online academic data bases including (Google Scholar, Web of Science and Pub Med), the relevant literature was extracted from the databases by using search terms of piRNAs and breast cancer as free-text words and also with the combination with OR /AND by may 2022. Recently, with the help of next-generation sequencing abnormal piRNA expression has been observed to associate with the occurrence and development of human cancers, such as breast cancer (BC). Recent investigation proposing piRNA as a prognostic and diagnostic biomarker based on their cancer-related interaction in the treatment of BC. This review aims to focus on the role of piRNAs in the initiation, progression, and the occurrence of breast cancer in order to understand its function and provide a better therapeutic strategy.

PIWI-interacting RNA (piRNA): a narrative review of its biogenesis, function, and emerging role in lung cancer.

Cancer remains elusive in many aspects, especially in its causes and control. After protein profiling, genetic screening, and mutation studies, scientists now have turned their attention to epigenetic modulation. This new arena has brought to light the world of noncoding RNA (ncRNA). Although very complicated and often confusing, ncRNA domains are now among the most attractive molecular markers for epigenetic control of cancer. Long ncRNA and microRNA (miRNA) have been studied best among the noncoding genome and huge data have accumulated regarding their inhibitory and promoting effects in cancer. Another sector of ncRNAs is the world of PIWI-interacting RNAs (piRNAs). Initially discovered with the asymmetric division of germline stem cells in the Drosophila ovary, piRNAs have a unique capability to associate with mammalian proteins analogous to P-element induced wimpy testis (PIWI) in Drosophila and are capable of silencing transposons. After a brief introduction to its discovery timelines, the present narrative review covers the biogenesis, function, and role of piRNAs in lung cancer. The effects on lung cancer are highlighted under sections of cell proliferation, stemness maintenance, metastasis, and overall survival, and the review concludes with a discussion of recent discoveries of another class of small ncRNAs, the piRNA-like RNAs (piR-Ls).

PiRNAs and PIWI Proteins as Diagnostic and Prognostic Markers of Genitourinary Cancers.

piRNAs (PIWI-interacting RNAs) are small non-coding RNAs capable of regulation of transposon and gene expression. piRNAs utilise multiple mechanisms to affect gene expression, which makes them potentially more powerful regulators than microRNAs. The mechanisms by which piRNAs regulate transposon and gene expression include DNA methylation, histone modifications, and mRNA degradation. Genitourinary cancers (GC) are a large group of neoplasms that differ by their incidence, clinical course, biology, and prognosis for patients. Regardless of the GC type, metastatic disease remains a key therapeutic challenge, largely affecting patients’ survival rates. Recent studies indicate that piRNAs could serve as potentially useful biomarkers allowing for early cancer detection and therapeutic interventions at the stage of non-advanced tumour, improving patient’s outcomes. Furthermore, studies in prostate cancer show that piRNAs contribute to cancer progression by affecting key oncogenic pathways such as PI3K/AKT. Here, we discuss recent findings on biogenesis, mechanisms of action and the role of piRNAs and the associated PIWI proteins in GC. We also present tools that may be useful for studies on the functioning of piRNAs in cancers.

PiRNAs and PIWI proteins as potential biomarkers in colorectal cancer

PIWI-interacting RNAs (piRNAs) are another subgroup of small non-coding RNAs emerging as key players in different biological activities, including regulating gene and protein expression, epigenetic silencing of transposable elements, and controlling the spermatogenesis by interacting with PIWI proteins. Recently, with the help of next-generation sequencing, abnormal piRNA expression has been observed in different types of cancer, such as colorectal cancer (CRC). A new investigation proposing piRNA as a prognostic and diagnostic biomarker in the treatment of CRC Therefore, this review focuses on the role of piRNAs in the initiation, progression, and metastasis of CRC and its molecular mechanisms to understand its function and provide a better therapeutic strategy. Keywords: PIWI-interacting RNA; piRNA; small RNA; colorectal cancer.

Abstract 11662: Extracellular Vesicle (EV)-Derived PiRNA, ImEX-Pi, is Protective in a Rat Model of Ischemia/Reperfusion Injury

Introduction: Cardiosphere-derived cells (CDCs ) are a population of heart-derived progenitors with demonstrated therapeutic efficacy in preclinical and clinical settings. CDCs exert their effect through the secretion of EVs, lipid-bilayer nanoparticles laden with bioactive molecules. Among the bioactive cargo identified in these immortalized CDC (imCDC)-derived EVs (imCDC-EV) are piwi RNAs (PiRNAs). PiRNAs bind Piwi proteins (members of the argonaute family) and regulate both the epigenome and transcriptome. The role of piRNAs (in particular EV-derived piRNAs) in modulating gene expression remains undescribed. Here we describe the role of a PiRNA highly enriched in imCDC-EVs (imEX-Pi). Methods: EVs were prepared by 24 hours hypoxic conditioning followed by normoxic recovery for three cycles. EVs were isolated from conditioned media using ultrafiltration. Fractions were analyzed for particle size, concentration and piRNA content. In vitro, bone marrow derived-macrophages (BMDM) were exposed to imCDC-EV, imEX-Pi and vehicle for transcriptomic analysis. In vivo, myocardial ischemia-reperfusion (I/R) injury was induced in 8-10-week-old Wistar-Kyoto female rats by LAD coronary ligation for 45 minutes followed by reperfusion. Twenty minutes later, imCDC-EV, imEX-Pi, scramble or vehicle were injected into the left ventricle with an aortic cross-clamp. Cardiac Troponin I levels, infarct size and circulating monocytes were assessed at 24 and 48 hrs post I/R. Results: RNA sequencing showed that piRNAs are enriched in both CDC-EV and imCDC-EV. ImEX-Pi was one of the most highly-expressed non-coding RNAs. In vitro , imEX-Pi altered the transcriptome of BMDMs compared to vehicle. This included upregulation of inflammatory and cell death pathways. In a rat model of I/R injury, imEX-Pi reduced infarct size and cardiac troponin levels compared to vehicle- and scrambled- treated animals. ImEX-Pi also significantly decreased circulating monocytes at 24 hours followed by a significant increase at 48hrs. Conclusions: We show that imEX-Pi is a key mediator of imCDC-EV therapeutic efficacy and that the principle target cells may be macrophages. This is further rationalized by the critical role that macrophages play in the injury and resolution response.

A Review of Discovery Profiling of PIWI-Interacting RNAs and Their Diverse Functions in Metazoans.

PIWI-interacting RNAs (piRNAs) are a class of small non-coding RNAs (sncRNAs) that perform crucial biological functions in metazoans and defend against transposable elements (TEs) in germ lines. Recently, ubiquitously expressed piRNAs were discovered in soma and germ lines using small RNA sequencing (sRNA-seq) in humans and animals, providing new insights into the diverse functions of piRNAs. However, the role of piRNAs has not yet been fully elucidated, and sRNA-seq studies continue to reveal different piRNA activities in the genome. In this review, we summarize a set of simplified processes for piRNA analysis in order to provide a useful guide for researchers to perform piRNA research suitable for their study objectives. These processes can help expand the functional research on piRNAs from previously reported sRNA-seq results in metazoans. Ubiquitously expressed piRNAs have been discovered in the soma and germ lines in Annelida, Cnidaria, Echinodermata, Crustacea, Arthropoda, and Mollusca, but they are limited to germ lines in Chordata. The roles of piRNAs in TE silencing, gene expression regulation, epigenetic regulation, embryonic development, immune response, and associated diseases will continue to be discovered via sRNA-seq.

Conserved and Widespread Expression of piRNA-Like Molecules and PIWI-Like Genes Reveal Dual Functions of Transposon Silencing and Gene Regulation in Pinctada fucata (Mollusca)

PIWI proteins and PIWI-interacting RNAs (piRNAs) suppress transposon activity in animals, thus safeguarding the genome from detrimental insertion mutagenesis. Recent studies revealed additional targets and functions of piRNAs in various animals. piRNAs are ubiquitously expressed in somatic tissues of the pearl oyster Pinctada fucata, however, the role of somatic piRNAs has not well characterized. This study reports the PIWI/piRNA pathway, including piRNA biogenesis and piRNA-mediated transposon silencing, and gene regulation in P. fucata. The biogenesis factors of PIWI, Zucchini, and HEN1, which are ubiquitous in somatic and gonadal tissues, were first identified in P. fucata using transcriptome analysis. Bioinformatics analyses suggested that different populations of piRNAs participate in the ping-pong amplification loop in a tissue-specific manner. In addition, a total of 69 piRNA clusters were identified in the genome of P. fucata based on the expression of piRNAs, which contained 26% transposons and enhanced for DNA/Crypton, LINE/CR1, SINE/Deu, and DNA/Academ. The expression patterns of the piRNAs and piRNA clusters in somatic tissues were not substantially different, but varied significantly between the somatic and gonadal tissues. Furthermore, locked-nucleic-acid modified oligonucleotide (LNA-antagonist) was used to silence single piRNA (piRNA0001) expression in P. fucata. Hundreds of endogenous genes were differentially expressed after piRNA silencing in P. fucata. Target prediction showed that some endogenous genes were targeted by piRNA0001, including twelve upregulated and nine downregulated genes after piRNA0001 silencing. The results indicated that piRNAs from somatic tissues may be related to gene regulation, whereas piRNAs from gonadal tissues are more closely associated to transposon silencing. This study will enhance our understanding of the role of piRNAs in mollusks, transposon silencing, and the regulatory function of the PIWI/piRNA pathway on protein-coding genes outside of germ line cells in P. fucata.

Identification and characterization of Piwi-interacting RNAs in human placentas of preeclampsia

Preeclampsia is a common disease of pregnancy that poses a serious threat to the safety of pregnant women and the fetus; however, the etiology of preeclampsia is inconclusive. Piwi-interacting RNAs (piRNAs) are novel non-coding RNAs that are present at high levels in germ cells and are associated with spermatogenesis. Emerging evidence demonstrated that piRNA is expressed in a variety of human tissues and is closely associated with tumorigenesis. However, changes in the piRNA expression profile in the placenta have not been investigated. In this study, we used small RNA sequencing to evaluate the differences in piRNA expression profiles between preeclampsia and control patients and potential functions. Differential expression analysis found 41 up-regulated and 36 down-regulated piRNAs in preeclamptic samples. In addition, the functional enrichment analysis of piRNAs target genes indicated that they were related to the extracellular matrix (ECM) formation and tissue-specific. Finally, we examined the expression pattern of the PIWL family proteins in the placenta, and PIWL3 and PIWIL4 were the primary subtypes in the human placenta. In summary, this study first summarized the changes in the expression pattern of piRNA in preeclampsia and provided new clues for the regulatory role of piRNA in the human placenta.

The Regulation and Role of piRNAs and PIWI Proteins in Cancer

P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are regulatory small non-coding RNAs that participate in transposon inactivation, chromatin regulation, and endogenous gene regulation. Numerous genetic and epigenetic factors regulate cell proliferation and tumor metastasis. PIWI proteins and piRNAs have been revealed to function in regulating upstream or downstream of oncogenes or tumor-suppressor genes in cancer tissues. In the present review, we summarize major recent findings in uncovering the regulation and role of PIWI proteins and piRNAs in tumorigenesis and highlight some of the promising applications of specific piRNAs in cancer therapeutics and as cancer biomarkers.

PiRNA-mediated gene regulation and adaptation to sex-specific transposon expression in D. melanogaster male germline.

Small noncoding piRNAs act as sequence-specific guides to repress complementary targets in Metazoa. Prior studies in Drosophila ovaries have demonstrated the function of the piRNA pathway in transposon silencing and therefore genome defense. However, the ability of the piRNA program to respond to different transposon landscapes and the role of piRNAs in regulating host gene expression remain poorly understood. Here, we comprehensively analyzed piRNA expression and defined the repertoire of their targets in Drosophila melanogaster testes. Comparison of piRNA programs between sexes revealed sexual dimorphism in piRNA programs that parallel sex-specific transposon expression. Using a novel bioinformatic pipeline, we identified new piRNA clusters and established complex satellites as dual-strand piRNA clusters. While sharing most piRNA clusters, the two sexes employ them differentially to combat the sex-specific transposon landscape. We found two piRNA clusters that produce piRNAs antisense to four host genes in testis, including CG12717/pirate, a SUMO protease gene. piRNAs encoded on the Y chromosome silence pirate, but not its paralog, to exert sex- and paralog-specific gene regulation. Interestingly, pirate is targeted by endogenous siRNAs in a sibling species, Drosophila mauritiana, suggesting distinct but related silencing strategies invented in recent evolution to regulate a conserved protein-coding gene.

Genome-wide mapping of Piwi association with specific loci in Drosophila ovaries.

Small noncoding RNA pathways have been implicated in diverse mechanisms of gene regulation. In Drosophila ovaries, Piwi binds to Piwi-interacting RNAs (piRNAs) of mostly 24–28 nucleotides (nt) and plays an important role in germline stem cell maintenance, transposon repression, and epigenetic regulation. To understand the mechanism underlying these functions, we report the application of the DamID-seq method to identify genome-wide binding sites of Piwi in Drosophila ovaries. Piwi localizes to at least 4535 euchromatic regions that are enriched with piRNA target sites. Surprisingly, the density of Piwi binding to euchromatin is much higher than in heterochromatin. Disrupting the piRNA binding of Piwi results in an overall change of the genomic binding profile, which indicates the role of piRNAs in directing Piwi to specific genomic sites. Most Piwi binding sites were either within or in the vicinity of protein-coding genes, particularly enriched near the transcriptional start and termination sites. The methylation signal near the transcriptional termination sites is significantly reduced when Piwi was mutated to become defective in piRNA binding. These observations indicate that Piwi might directly regulate the expression of many protein-coding genes, especially through regulating the 3' ends of targeted transcripts.

Leprosy piRnome: exploring new possibilities for an old disease

Leprosy, which is caused by the human pathogen Mycobacterium leprae, causes nerve damage, deformity and disability in over 200,000 people every year. Because of the long doubling time of M. leprae (13 days) and the delayed onset of detectable symptoms, which is estimated to be approximately 3–7 years after infection, there is always a large percentage of subclinically infected individuals in the population who will eventually develop the disease, mainly in endemic countries. piRNAs comprise the largest group of small noncoding RNAs found in humans, and they are distinct from microRNAs (miRNAs) and small interfering RNAs (siRNAs). piRNAs function in transposon silencing, epigenetic regulation, and germline development. The functional role of piRNAs and their associated PIWI proteins have started to emerge in the development of human cancers and viral infections, but their relevance to bacterial diseases has not been investigated. The present study reports the piRNome of human skin, revealing that all but one of the piRNAs examined are downregulated in leprosy skin lesions. Considering that one of the best characterized functions of piRNAs in humans is posttranscriptional mRNA silencing, their functions are similar to what we have described for miRNAs, including acting on apoptosis, M. leprae recognition and engulfment, Schwann cell (SC) demyelination, epithelial–mesenchymal transition (EMT), loss of sensation and neuropathic pain. In addition to new findings on leprosy physiopathology, the discovery of relevant piRNAs involved in disease processes in human skin may provide new clues for therapeutic targets, specifically to control nerve damage, a prominent feature of leprosy that has no currently available pharmaceutical treatment.

Role of PIWI-interacting RNAs on cell survival: Proliferation, apoptosis, and cycle.

PIWI-interacting RNAs (piRNAs) are a kind of non-coding small RNAs, which play a biological role by specifically binding to PIWI proteins. Studies have demonstrated that piRNAs play a significant role in germline cell growth by repressing transposable elements, especially in the regulation of DNA methylation. Recently increasing evidence revealed that piRNAs involved in the regulation of cell proliferation, apoptosis, and cycle; however, the mechanism of piRNAs is unclear. This review summarizes the research progress regarding the roles of piRNAs in the cell proliferation, apoptosis, and cycle.

PIWI-Interacting RNA-004800 Is Regulated by S1P Receptor Signaling Pathway to Keep Myeloma Cell Survival.

PIWI-interacting RNA (piRNA) is a kind of non-coding single stranded RNA which plays major roles in epigenetic expressions, genome rearrangement, and regulation of gene and protein. Because piRNAs are abnormally expressed in various cancers, they can be used as novel biomarkers and therapeutic targets. However, the roles of piRNAs in cancer cell growth and survival are not well-known. Here, we are the first to provide evidence that PIWI-interacting RNA-004800 (piR-004800) is overexpressed in both exosomes from multiple myeloma (MM) patients' bone marrow supernatant and primary MM cells. The expression level of piR-004800 is positively correlated with the stages of MM, according to the international staging system (ISS). In MM cell lines, downregulation of piR-004800 induced apoptosis and autophagic cell death. This was accompanied by in vitro and in vivo inhibition of cell proliferation. Our previous study shows that sphingosine-1-phosphate receptor (S1PR) signaling pathway plays a crucial part in MM cell proliferation. In this study, we find that S1PR signaling pathway can regulate the PI3K/Akt/mTOR pathway through control of piR-004800 expressions. Taken together our data supports an oncogenic role for piR-004800 in MM, which sheds insight into a new mechanism that may lead to therapeutic targets in MM, an incurable plasma cell neoplasm.

PiRNA-63076 contributes to pulmonary arterial smooth muscle cell proliferation through acyl-CoA dehydrogenase.

Piwi‐interacting RNAs (piRNAs) are thought to be germline‐specific and to be involved in maintaining genome stability during development. Recently, piRNA expression has been identified in somatic cells in diverse organisms. However, the roles of piRNAs in pulmonary arterial smooth muscle cell (PASMC) proliferation and the molecular mechanism underlying the hypoxia‐regulated pathological process of pulmonary hypertension are not well understood. Using hypoxic animal models, cell and molecular biology, we obtained the first evidence that the expression of piRNA‐63076 was up‐regulated in hypoxia and was positively correlated with cell proliferation. Subsequently, we showed that acyl‐CoA dehydrogenase (Acadm), which is negatively regulated by piRNA‐63076 and interacts with Piwi proteins, was involved in hypoxic PASMC proliferation. Finally, Acadm inhibition under hypoxia was partly attributed to DNA methylation of the Acadm promoter region mediated by piRNA‐63076. Overall, these findings represent invaluable resources for better understanding the role of epigenetics in pulmonary hypertension associated with piRNAs.

PiRNAs in Gastric Cancer: A New Approach Towards Translational Research.

Background: Gastric cancer is currently the third leading cause of cancer-related deaths worldwide, usually diagnosed at late stages. The development of new biomarkers to improve its prevention and patient management is critical for disease control. piRNAs are small regulatory RNAs important for gene silencing mechanisms, mainly associated with the silencing of transposable elements. piRNA pathways may also be involved in gene regulation and the deregulation of piRNAs may be an important factor in carcinogenic processes. Thus, several studies suggest piRNAs as potential cancer biomarkers. Translational studies suggest that piRNAs may regulate key genes and pathways associated with gastric cancer progression, though there is no functional annotation in piRNA databases. The impacts of genetic variants in piRNA genes and their influence in gastric cancer development remains elusive, highlighting the gap in piRNA regulatory mechanisms knowledge. Here, we discuss the current state of understanding of piRNA-mediated regulation and piRNA functions and suggest that genetic alterations in piRNA genes may affect their functionality, thus, it may be associated with gastric carcinogenesis. Conclusions: In the era of precision medicine, investigations about genetic and epigenetic mechanisms are essential to further comprehend gastric carcinogenesis and the role of piRNAs as potential biomarkers for translational research.