PIWI-interacting RNAs: Critical roles and therapeutic targets in cancer

Non-Coding RNAs in Cancer: Structure, Function, and Clinical Application

We are on the brink of a paradigm shift in both theoretical and clinical oncology. Genomic and transcriptomic profiling, alongside personalized approaches that account for individual patient variability, are increasingly shaping discourse. Discussions on the future of personalized cancer medicine are mainly dominated by the potential of non-coding RNAs (ncRNAs), which play a prominent role in cancer progression and metastasis formation by regulating the expression of oncogenic or tumor suppressor proteins at transcriptional and post-transcriptional levels; furthermore, their cell-free counterparts might be involved in intercellular communication. Non-coding RNAs are considered to be promising biomarker candidates for early diagnosis of cancer as well as potential therapeutic agents. This review aims to provide clarity amidst the vast body of literature by focusing on diverse species of ncRNAs, exploring the structure, origin, function, and potential clinical applications of miRNAs, siRNAs, lncRNAs, circRNAs, snRNAs, snoRNAs, eRNAs, paRNAs, YRNAs, vtRNAs, and piRNAs. We discuss molecular methods used for their detection or functional studies both in vitro and in vivo. We also address the challenges that must be overcome to enter a new era of cancer diagnosis and therapy that will reshape the future of oncology.

miRNAs, piRNAs, and lncRNAs: A triad of non-coding RNAs regulating the neurovascular unit in diabetic retinopathy and their therapeutic potentials

Diabetic Retinopathy (DR), a leading complication of diabetes mellitus, has long been considered as a microvascular disease of the retina. However, recent evidence suggests that DR is a neurovascular disease, characterized by the degeneration of retinal neural tissue and microvascular abnormalities encompassing ischemia, neovascularization, and blood-retinal barrier breakdown, ultimately leading to blindness. The intricate relationship between the retina and vascular cells constitutes a neurovascular unit, a multi-cellular framework of retinal neurons, glial cells, immune cells, and vascular cells, which facilitates neurovascular coupling, linking neuronal activity to blood flow. These interconnections between the neurovascular components get compromised due to hyperglycemia and are further associated with the progression of DR early on in the disease. As a result, therapeutic approaches are needed to avert the advancement of DR by acting at its initial stage to delay or prevent the pathogenesis. Non-coding RNAs (ncRNAs) such as microRNAs, piwi-interacting RNAs, and long non-coding RNAs regulate various cellular components in the neurovascular unit. These ncRNAs are key regulators of neurodegeneration, apoptosis, inflammation, and oxidative stress in DR. In this review, research related to alterations in the expression of ncRNAs and, correspondingly, their effect on the disintegration of the neurovascular coupling will be discussed briefly to understand the potential of ncRNAs as therapeutic targets for treating this debilitating disease.

Exosomal ncRNAs in liquid biopsies for lung cancer

Exosomal non-coding RNAs (ncRNAs) have become essential contributors to advancing and treating lung cancers (LCs). The development of liquid biopsies that utilize exosomal ncRNAs (exo-ncRNAs) offers an encouraging method for diagnosing, predicting, and treating LC. This thorough overview examines the dual function of exo-ncRNAs as both indicators for early diagnosis and avenues for LC treatment. Exosomes are tiny vesicles secreted by various cells, including cancerous cells, enabling connection between cells by delivering ncRNAs. These ncRNAs, which encompass circular RNAs, long ncRNAs, and microRNAs, participate in the modulation of gene expression and cellular functions. In LC, certain exo-ncRNAs are linked to tumour advancement, spread, and treatment resistance, positioning them as promising non-invasive indicators in liquid biopsies. Additionally, targeting these ncRNAs offers potential for innovative treatment approaches, whether by suppressing harmful ncRNAs or reinstating the activity of tumour-suppressing ones. This review emphasizes recent developments in the extraction and analysis of exo-ncRNAs, their practical applications in LC treatment, and the challenges and prospects for translating these discoveries into clinical usage. Through this detailed examination of the current state of the art, we aim to highlight the significant potential of exo-ncRNAs for LC diagnostics and treatments.

Biological functions and clinical significance of tRNA-derived small fragment (tsRNA) in tumors: Current state and future perspectives

A new class of noncoding RNAs, tsRNAs are not only abundant in humans but also have high tissue specificity. Recently, an increasing number of studies have explored the correlations between tsRNAs and tumors, showing that tsRNAs can affect biological behaviors of tumor cells, such as proliferation, apoptosis and metastasis, by modulating protein translation, RNA transcription or posttranscriptional regulation. In addition, tsRNAs are widely distributed and stably expressed, which endows them with broad application prospects in diagnosing and predicting the prognosis of tumors, and they are expected to become new biomarkers. However, notably, the current research on tsRNAs still faces problems that need to be solved. In this review, we describe the characteristics of tsRNAs as well as their unique features and functions in tumors. Moreover, we also discuss the potential opportunities and challenges in clinical applications and research of tsRNAs.

A multi-cycle signal amplification-mediated single quantum dot nanosensor for PIWI-interacting RNA detection

We construct a single quantum dot-based nanosensor for piRNA detection based on ligation-mediated multi-cycle signal amplification. This nanosensor is homogenous, selective, and sensitive with a detection limit of 0.104 fM. Moreover, it can detect the endogenous piRNA level in different cell lines, and discriminate cancer tissues from normal tissues.

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.

TP53 mutations correlate with the non-coding RNA content of small extracellular vesicles in melanoma

Non-coding RNAs (ncRNAs) are important regulators of gene expression. They are expressed not only in cells, but also in cell-derived extracellular vesicles (EVs). The mechanisms controlling their loading and sorting remain poorly understood. Here, we investigated the impact of TP53 mutations on the non-coding RNA content of small melanoma EVs. After purification of small EVs from six different patient-derived melanoma cell lines, we characterized them by small RNA sequencing and lncRNA microarray analysis. We found that TP53 mutations are associated with a specific micro and long non-coding RNA content in small EVs. Then, we showed that long and small non-coding RNAs enriched in TP53 mutant small EVs share a common sequence motif, highly similar to the RNA-binding motif of Sam68, a protein interacting with hnRNP proteins. This protein thus may be an interesting partner of p53, involved in the expression and loading of the ncRNAs. To conclude, our data support the existence of cellular mechanisms associate with TP53 mutations which control the ncRNA content of small EVs in melanoma.