Novel evidence for oncogenic piRNA-823 as a promising prognostic biomarker and a potential therapeutic target in colorectal cancer

The potential emerging role of piRNA/PIWI complex in virus infection

P-element-induced wimpy testis-interacting RNAs (piRNAs), a class of small noncoding RNAs with about 24-32 nucleotides, often interact with PIWI proteins to form a piRNA/PIWI complex that could influence spermiogenesis, transposon silencing, epigenetic regulation, etc. PIWI proteins have a highly conserved function in a variety of species and are usually expressed in germ cells. However, increasing evidence has revealed the important role of the piRNA/PIWI complex in the occurrence and prognosis of various human diseases and suggests its potential application in the diagnosis and treatment of related diseases, becoming a prominent marker for these human diseases. Recent studies have confirmed that piRNA/PIWI complexes or piRNAs are abnormally expressed in some viral infections, effecting disease progression and viral replication. In this study, we reviewed the association between the piRNA/PIWI complex and several human disease-associated viruses, including human papillomavirus, human immunodeficiency virus, human rhinovirus, severe acute respiratory syndrome coronavirus 2, respiratory syncytial virus, and herpes simplex virus type 1.

Potential molecular mechanisms and clinical implications of piRNAs in preeclampsia: a review

Preeclampsia is a multisystem progressive condition and is one of the most serious complications of pregnancy. Owing to its unclear pathogenesis, there are no precise and effective therapeutic targets for preeclampsia, and the only available treatment strategy is to terminate the pregnancy and eliminate the clinical symptoms. In recent years, non-coding RNAs have become a hotspot in preeclampsia research and have shown promise as effective biomarkers for the early diagnosis of preeclampsia over conventional biochemical markers. PIWI-interacting RNAs, novel small non-coding RNA that interact with PIWI proteins, are involved in the pathogenesis of various diseases at the transcriptional or post-transcriptional level. However, the mechanisms underlying the role of PIWI-interacting RNAs in the pathogenesis of preeclampsia remain unclear. In this review, we discuss the findings of existing studies on PIWI-interacting RNA biogenesis, functions, and their possible roles in preeclampsia, providing novel insights into the potential application of PIWI-interacting RNAs in the early diagnosis and clinical treatment of preeclampsia.

The role of piRNAs in predicting and prognosing in cancer: a focus on piRNA-823 (a systematic review and meta-analysis)

INTRODUCTION

This article examines the potential of using liquid biopsy with piRNAs to study cancer survival outcomes. While previous studies have explored the relationship between piRNA expression and cancer patient outcomes, a comprehensive investigation is still lacking. To address this gap, we conducted a systematic review and meta-analysis of existing literature.

METHODS

We searched major online databases up to February 2024 to identify articles reporting on the role of piRNA in cancer patient survival outcomes. Our meta-analysis used a random-effects model to pool hazard ratios with 95% confidence intervals (CI) and assess the prognostic value of deregulated piRNA-823. For survival analysis, the Kaplan-Meier method and COX analysis were used.

RESULTS

Out of 6104 articles screened, 20 met our inclusion criteria. Our analysis revealed that dysregulated piRNA expression is associated with cancer patient survival outcomes. Specifically, our meta-analysis found that overexpression of piR-823 is significantly linked with poorer overall survival in patients with colorectal cancer and renal cell cancer (HR: 3.82, 95% CI = [1.81, 8.04], I2 = 70%).

CONCLUSION

Our findings suggest that various piRNAs may play a role in cancer survival outcomes and that piRNA-823 in particular holds promise as a prognostic biomarker for multiple human cancers.

IMPLICATIONS FOR CANCER SURVIVORS

Our systematic review and meta-analysis of piRNA-823 has important implications for cancer survivors. Our findings suggest that piRNA-823 can be used as a prognostic biomarker for predicting cancer recurrence and survival rates. This information can help clinicians develop personalized treatment plans for cancer survivors, which can improve their quality of life and reduce the risk of recurrence.

The burgeoning importance of PIWI-interacting RNAs in cancer progression

PIWI-interacting RNAs (piRNAs) are a class of small noncoding RNA molecules that specifically bind to piwi protein family members to exert regulatory functions in germ cells. Recent studies have found that piRNAs, as tissue-specific molecules, both play oncogenic and tumor suppressive roles in cancer progression, including cancer cell proliferation, metastasis, chemoresistance and stemness. Additionally, the atypical manifestation of piRNAs and PIWI proteins in various malignancies presents a promising strategy for the identification of novel biomarkers and therapeutic targets in the diagnosis and management of tumors. Nonetheless, the precise functions of piRNAs in cancer progression and their underlying mechanisms have yet to be fully comprehended. This review aims to examine current research on the biogenesis and functions of piRNA and its burgeoning importance in cancer progression, thereby offering novel perspectives on the potential utilization of piRNAs and piwi proteins in the management and treatment of advanced cancer.

The strict regulation of HIF-1α by non-coding RNAs: new insight towards proliferation, metastasis, and therapeutic resistance strategies

The hypoxic environment is prominently witnessed in most solid tumors and is associated with the promotion of cell proliferation, epithelial-mesenchymal transition (EMT), angiogenesis, metabolic reprogramming, therapeutic resistance, and metastasis of tumor cells. All the effects are mediated by the expression of a transcription factor hypoxia-inducible factor-1α (HIF-1α). HIF-1α transcriptionally modulates the expression of genes responsible for all the aforementioned functions. The stability of HIF-1α is regulated by many proteins and non-coding RNAs (ncRNAs). In this article, we have critically discussed the crucial role of ncRNAs [such as microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), Piwi-interacting RNAs (piRNAs), and transfer RNA (tRNA)-derived small RNAs (tsRNAs)] in the regulation of stability and expression of HIF-1α. We have comprehensively discussed the molecular mechanisms and relationship of HIF-1α with each type of ncRNA in either promotion or repression of human cancers and therapeutic resistance. We have also elaborated on ncRNAs that are in clinical examination for the treatment of cancers. Overall, the majority of aspects concerning the relationship between HIF-1α and ncRNAs have been discussed in this article.

A Review on Emerging Techniques for Diagnosis of Colorectal Cancer

Common detection methods in practice for diagnosing colorectal cancer (CRC) are painful and invasive leading to less participation of individuals for CRC diagnosis. Whereas, improved or enhanced imaging systems and other minimally invasive techniques with shorter detection times deliver greater detail and less discomfort in individuals. Thus, this review is a summary of the diagnostic tests, ranging from the simple potential use in developing a flexible CRC treatment to the patient's potential benefits in receiving less invasive procedures and the advanced treatments that might provide a better assessment for the diagnosis of CRC and reduce the mortality related to CRC.

Elevated expression patterns of P-element Induced Wimpy Testis (PIWI) transcripts are potential candidate markers for Hepatocellular Carcinoma

BACKGROUND

P-Element-induced wimpy testis (PIWI) proteins, when in combination with PIWI-interacting RNA (piRNA), are engaged in the epigenetic regulation of gene expression in germline cells. Different types of tumour cells have been found to exhibit abnormal expression of piRNA, PIWIL-mRNAs, and proteins. We aimed to determine the mRNA expression profiles of PIWIL1, PIWIL2, PIWIL3, & PIWIL4, in hepatocellular carcinoma patients, and to associate their expression patterns with clinicopathological features.

METHODS

The expression patterns of PIWIL1, PIWIL2, PIWIL3, PIWIL4 mRNA, was assessed via real-time quantitative polymerase chain reaction (RT-QPCR), on tissue and serum samples from HCC patients, their impact for diagnosis was evaluated by ROC curves, prognostic utility was determined, and In Silico analysis was conducted for predicted variant detection, association with HCC microRNAs and Network Analysis.

RESULTS

Expression levels were significantly higher in both HCC tissue and serum samples than in their respective controls (p< 0.001). Additionally, the diagnostic performance was assessed, Risk determination was found to be statistically significant.

CONCLUSION

PIWIL mRNAs are overexpressed in HCC tissue and serum samples, the expression patterns could be valuable molecular markers for HCC, due to their association with age, tumour grade and pattern. To the best of our knowledge, our study is the first to report the expression levels of all PIWIL mRNA and to suggest their remarkable values as diagnostic and prognostic biomarkers, in addition to their correlation to HCC development. Additionally, a therapeutic opportunity might be also suggested through in silico miRNA prediction for HCC and PIWIL genes through DDX4 and miR-124-3p.

Role of gene therapy in treatment of cancer with craniofacial regeneration-current molecular strategies, future perspectives, and challenges: a narrative review

Gene therapy involves the introduction of foreign genetic material into host tissue to alter the expression of genetic products. Gene therapy represents an opportunity to alter the course of various diseases. Hence, genetic products utilizing safe and reliable vectors with improved biotechnology will play a critical role in the treatment of various diseases in the future. This review summarizes various important vectors for gene therapy along with modern techniques for potential craniofacial regeneration using gene therapy. This review also explains current molecular approaches for the management and treatment of cancer using gene therapy. The existing literature was searched to find studies related to gene therapy and its role in craniofacial regeneration and cancer treatment. Various databases such as PubMed, Science Direct, Scopus, Web of Science, and Google Scholar were searched for English language articles using the keywords "gene therapy," "gene therapy in present scenario," "gene therapy in cancer," "gene therapy and vector," "gene therapy in diseases," and "gene therapy and molecular strategies."

Non-Coding RNAs in Human Cancer and Other Diseases: Overview of the Diagnostic Potential

Non-coding RNAs (ncRNAs) are abundant single-stranded RNA molecules in human cells, involved in various cellular processes ranging from DNA replication and mRNA translation regulation to genome stability defense. MicroRNAs are multifunctional ncRNA molecules of 18-24 nt in length, involved in gene silencing through base-pair complementary binding to target mRNA transcripts. piwi-interacting RNAs are an animal-specific class of small ncRNAs sized 26-31 nt, responsible for the defense of genome stability via the epigenetic and post-transcriptional silencing of transposable elements. Long non-coding RNAs are ncRNA molecules defined as transcripts of more than 200 nucleotides, their function depending on localization, and varying from the regulation of cell differentiation and development to the regulation of telomere-specific heterochromatin modifications. The current review provides recent data on the several forms of small and long non-coding RNA's potential to act as diagnostic, prognostic or therapeutic target for various human diseases.

PIWI interacting RNA-13643 contributes to papillary thyroid cancer development through acting as a novel oncogene by facilitating PRMT1 mediated GLI1 methylation

BACKGROUND

Recently, aberrant expression of PIWI-interacting RNAs (piRNAs) has been discovered in a variety of cancer cells. However, the roles of PIWI proteins and piRNAs in papillary thyroid carcinoma (PTC) are still elusive.

METHODS

RT-qPCR and Northern blotting were used to evaluate piR-13643 levels in PTC and para-carcinoma tissues, as well as in PTC cell lines. piR-13643 mimic and piR-13643 inhibitor were transfected into K-1 and B-CPAP cells. CCK-8, Transwell, annexin V-FITC/PI, flow cytometry and Western blot assays were performed to measure cell proliferation, invasion, apoptosis, cell cycle and E-cadherin and Vimentin proteins, respectively. Total RNA from B-CPAP cells was pulled down with PIWIL1, PIWIL2, or PIWIL3 specific antibodies or IgG as a control, respectively, followed by detection of piR-13643 expression with RT-qPCR. Immunoblotting of PRMT1 was detected in piR-13643 / PIWIL1 complex immune-precipitates by Co-IP assay. Subsequently, PRMT1 protein expression was detected by stably transfection of Flag tagged GLI1 (Flag-GLI1) into B-CPAP cells. Methylation assay with PRMT1 and wild-type or R597 lysine (R597K)-mutant GLI1. Then rescue experiments were applied to explore effects of piR-13643 and GLI1 on the malignant behavior of PTC cells. B-CPAP cells transfected with piR-13643 inhibitor were subcutaneously injected into nude mice to evaluate the effect of piR-13643 knockdown on the xenograft tumor growth of PTC.

RESULTS

piR-13643 was elevated in PTC patient specimens and cell lines. piR-13643 overexpression facilitated cell proliferation, invasion and Vimentin level, and restrained apoptosis and E-cadherin expression, whereas piR-13643 knockdown showed the opposite results. Mechanically, piR-13643 could bind to PIWIL1 to form the PIWIL1/piR-13643 complex, and PRMT1 enhanced GLI1 transcription by methylating GLI1 at R597. Further, PIWIL1/piR-13643 promoted PRMT1-mediated GLI1 methylation. GLI1 knockdown countered the effects of piR-13643 mimic on cell malignant behaviors. piR-13643 knockdown preeminently prevented the xenograft tumor growth of PTC in vivo.

CONCLUSIONS

This study confirmed that piR-13643 facilitates PTC malignant behaviors in vitro and in vivo by promoting PRMT1-mediated GLI1 methylation via forming a complex with PIWIL1, which may provide a novel insight for PTC treatment.

piRNA-18 Inhibition Cell Proliferation, Migration and Invasion in Colorectal Cancer

Colorectal cancer is one of the most prevalent malignancies worldwide. Evidences indicate that piRNA-18 are closely involved and contributed to tumorigenesis and cancer progression. Therefore, it is very necessary to investigate the effects of piRNA-18 on the proliferation, migration, and invasiveness of colorectal cancer cells, so as to provide theoretical basis for finding new biomarkers and accurate diagnosis and treatment of colorectal cancer. Here, Five pairs of colorectal cancer tissue samples and their corresponding adjacent samples were analyzed by real-time immunofluorescence quantitative PCR and the difference in piRNA-18 expression among colorectal cancer cell lines was further verified. MTT assay were used to study the changes in the proliferation of colorectal cancer cell lines after piRNA-18 overexpression. Wound-healing assay and Transwell assay were used to study the changes in migration and invasion. Flow cytometry were used to study the changes in apoptosis and cycle. SC inoculation of colorectal cancer cell lines into nude mice were used to observe the effect in the proliferation. piRNA-18 was lowlier expressed than adjacent tissues and normal intestinal mucosal epithelial cells in colorectal cancer and colorectal cancer cell line. After overexpression of piRNA-18, cell proliferation and migration as well as invasiveness in SW480 and LOVO cells decreased. The cell lines with piRNA-18 overexpression had obvious G1/S phase arrest in cell cycle, and the weight and volume of subcutaneously transplanted tumors are decreased. Our findings highlighted that piRNA-18 may play an inhibitory role in colorectal cancer.

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.

PiRNA Obtained through Liquid Biopsy as a Possible Cancer Biomarker

In recent years PIWI-interacting RNAs (piRNAs) have gained the interest of scientists, mainly because of their possible implications in cancer. Many kinds of research showed how their expression can be linked to malignant diseases. However, most of them evaluated the expression of piRNAs in tumor tissues. It was shown how these non-coding RNAs can interfere with many signaling pathways involved in the regulation of proliferation or apoptosis. A comparison of piRNA expression in tumor tissue and adjacent healthy tissues has demonstrated they can be used as biomarkers. However, this way of obtaining samples has a significant drawback, which is the invasiveness of such a procedure. Liquid biopsy is an alternative for acquiring biological material with little to no harm to a patient. Several different piRNAs in various types of cancer were shown to be expressed in bodily fluids such as blood or urine. Furthermore, their expression significantly differed between cancer patients and healthy individuals. Hence, this review aimed to assess the possible use of liquid biopsy for cancer diagnosis with piRNAs as biomarkers.

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

P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are a novel class of small regulatory RNAs (approximately 24-31 nucleotides in length) that often bind to members of the PIWI protein family. piRNAs regulate transposons in animal germ cells; piRNAs are also specifically expressed in many human tissues and regulate pivotal signaling pathways. Additionally, the abnormal expression of piRNAs and PIWI proteins has been associated with various malignant tumours, and multiple mechanisms of piRNA-mediated target gene dysregulation are involved in tumourigenesis and progression, suggesting that they have the potential to serve as new biomarkers and therapeutic targets for tumours. However, the functions and potential mechanisms of action of piRNAs in cancer have not yet been elucidated. This review summarises the current findings on the biogenesis, function, and mechanisms of piRNAs and PIWI proteins in cancer. We also discuss the clinical significance of piRNAs as diagnostic or prognostic biomarkers and therapeutic tools for cancer. Finally, we present some critical questions regarding piRNA research that need to be addressed to provide insight into the future development of the field.

Safety and long-term prognosis of simultaneous versus staged resection in synchronous colorectal cancer with liver metastasis: a systematic review and meta-analysis

PURPOSE

The optimal time point for surgical resection of synchronous colorectal liver metastases (SCLMs) is still controversial. This meta-analysis evaluated the safety and long-term prognoses of simultaneous and staged resection of SCLM to provide a reference for clinical selection.

METHODS

A systematic literature search for studies published by October 2022 was performed using PubMed, Web of Science, Embase, Scopus and Cochrane Library. The evaluated outcome parameters were total, gastrointestinal and hepatic complications, as well as perioperative mortality, intraoperative blood loss, total hospital stay, 5-year disease-free survival (DFS) and 5-year overall survival (OS).

RESULTS

This meta-analysis included 22 nonrandomised and one randomised study comprising 4862 patients. The patients undergoing simultaneous resection of SCLM had similar total (OR = 0.88, 95% CI [0.66-1.19], P = 0.409), gastrointestinal (OR = 1.19, 95% CI [0.89-1.59], P = 0.241) and hepatic (OR = 1.04, 95% CI [0.83-1.31], P = 0.734) complications, as well as perioperative mortality (OR = 1.79, 95% CI [0.88-3.64], P = 0.108), 5-year DFS (HR = 1.26, 95% CI [0.96-1.66], P = 0.098) and 5-year OS (HR = 1.13, 95% CI [0.95-1.34], P = 0.164). Lower intraoperative blood loss (SMD = - 0.39, 95% CI [- 0.60 to - 0.18], P < 0.001) and shorter total hospital stay (WMD = - 5.43, 95% CI [- 7.29 to - 3.58], P < 0.001) were observed in the simultaneous-resection group versus the staged group.

CONCLUSIONS

Simultaneous resection is safe and effective for SCLM patients. The long-term prognosis is equivalent to that of the traditional staged resection. Correct selection of resectable SCLM patients for the simultaneous resection of the primary tumour and liver metastases can be the first choice. Owing to the potential heterogeneity, more RCTs should be included to verify our conclusions.

Non-coding RNA-related antitumor mechanisms of marine-derived agents

In the last two decades, natural active substances have attracted great attention in developing new antitumor drugs, especially in the marine environment. A series of marine-derived compounds or derivatives with potential antitumor effects have been discovered and developed, but their mechanisms of action are not well understood. Emerging studies have found that several tumor-related signaling pathways and molecules are involved in the antitumor mechanisms of marine-derived agents, including noncoding RNAs (ncRNAs). In this review, we provide an update on the regulation of marine-derived agents associated with ncRNAs on tumor cell proliferation, apoptosis, cell cycle, invasion, migration, drug sensitivity and resistance. Herein, we also describe recent advances in marine food-derived ncRNAs as antitumor agents that modulate cross-species gene expression. A better understanding of the antitumor mechanisms of marine-derived agents mediated, regulated, or sourced by ncRNAs will provide new biomarkers or targets for potential antitumor drugs from preclinical discovery and development to clinical application.

piRNAs and PIWI proteins as potential biomarkers in ‌Breast cancer

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Serum-derived piR-hsa-164586 of extracellular vesicles as a novel biomarker for early diagnosis of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is a major cause of death in those with malignant tumors. To achieve the early diagnosis of NSCLC, we investigated serum-derived Piwi-interacting RNA (piRNA) of extracellular vesicles to filter diagnostic biomarkers for NSCLC. High-throughput sequencing from cancerous tissues and adjacent noncancerous tissues in patients with NSCLC was first applied to recognize candidate piRNAs as diagnostic biomarkers. These screened piRNAs were further validated in 115 patients (including 95 cases in stage I) and 47 healthy individuals using quantitative real-time PCR (qRT-PCR). We showed that piR-hsa-164586 was significantly upregulated compared with paracancerous tissues and extracellular vesicles from the serum samples of healthy individuals. Moreover, the area under the curve (AUC) value of piR-hsa-164586 was 0.623 and 0.624 to distinguish patients with all stages or stage I of NSCLC, respectively, from healthy individuals. The diagnostic performance of piR-hsa-164586 was greatly improved compared with the cytokeratin-19-fragment (CYFRA21-1). Additionally, piR-hs-164586 was associated with the clinical characteristics of patients with NSCLC. Its expression was associated with the age and TNM stage of patients with NSCLC, indicating that it can serve as an effective and promising biomarker for the early diagnosis of NSCLC.

PIWI-interacting RNAs in cancer: Biogenesis, function, and clinical significance

PIWI-interacting RNAs (piRNAs) are a less-studied class of small non-coding RNAs approximately 24–31 nucleotides in length. They express in germline and somatic cells and form complexes with PIWI proteins to exert regulatory effects. New studies show that piRNAs are aberrantly expressed in various cancers. In this review, we focus on those piRNAs that are associated with cancer hallmarks such as proliferation, invasion, and chemoresistance and discuss their potential as biomarkers for cancer diagnosis and prognosis.

Emerging roles of PIWI-interacting RNAs (piRNAs) and PIWI proteins in head and neck cancer and their potential clinical implications

Head and neck squamous cell carcinoma (HNSCC) are among the well-known neoplasms originating in the oral cavity, pharynx, and larynx. Despite advancements in chemotherapy, radiotherapy, and surgery, the survival rates of the patients are low, which has posed a major therapeutic challenge. A growing number of non-coding RNAs (ncRNAs), for instance, microRNAs, have been identified whose abnormal expression patterns have been implicated in HNSCC. However, more recently, several seminal research has shown that piwi-interacting RNAs (piRNAs), a promising and young class of small ncRNA, are linked to the emergence and progression of cancer. They can regulate transposable elements (TE) and gene expression through multiple mechanisms, making them potentially more powerful regulators than miRNAs. Hence, they can be more promising ncRNAs candidates for cancer therapeutic intervention. Here, we surveyed the roles and clinical implications of piRNAs and their PIWI proteins partners in tumorigenesis and associated molecular processes of cancer, with a particular focus on HNSCC, to offer a new avenue for diagnosis, prognosis, and therapeutic interventions for the malignancy, improving patient's outcomes.

PIWI-Interacting RNAs (piRNAs): Promising Applications as Emerging Biomarkers for Digestive System Cancer

PIWI-interacting RNAs (piRNAs) are a novel type of small non-coding RNAs (sncRNAs), which are 26–31 nucleotides in length and bind to PIWI proteins. Although piRNAs were originally discovered in germline cells and are thought to be essential regulators for germline preservation, they can also influence gene expression in somatic cells. An increasing amount of data has shown that the dysregulation of piRNAs can both promote and repress the emergence and progression of human cancers through DNA methylation, transcriptional silencing, mRNA turnover, and translational control. Digestive cancers are currently a major cause of cancer deaths worldwide. piRNAs control the expression of essential genes and pathways associated with digestive cancer progression and have been reported as possible biomarkers for the diagnosis and treatment of digestive cancer. Here, we highlight recent advances in understanding the involvement of piRNAs, as well as potential diagnostic and therapeutic applications of piRNAs in various digestive cancers.

Emerging noncoding RNAs contained in extracellular vesicles: rising stars as biomarkers in lung cancer liquid biopsy

Lung cancer has a high morbidity and mortality rate, and affected patients have a poor prognosis and low survival. The therapeutic approaches for lung cancer treatment, including surgery, radiotherapy, and chemotherapy, are not completely effective, due to late diagnosis. Although the identification of genetic drivers has contributed to the improvement of lung cancer clinical management, the discovery of new diagnostic and prognostic tools remains a critical issue. Liquid biopsy (LB) represents a minimally invasive approach and practical alternative source to investigate tumor-derived alterations and to facilitate the selection of targeted therapies. LB allows for the testing of different analytes such as circulating tumor cells, extracellular vesicles (EVs), tumor-educated platelets, and cell-free nucleic acids including DNAs, RNAs, and noncoding RNAs (ncRNAs). Several regulatory factors control the key cellular oncogenic pathways involved in cancers. ncRNAs have a wide range of regulatory effects in lung cancers. This review focuses on emerging regulatory ncRNAs, freely circulating in body fluids or shuttled by EVs, such as circular-RNAs, small nucleolar-RNAs, small nuclear-RNAs, and piwi-RNAs, as new biomarkers for early detection, prognosis, and monitoring of therapeutic strategy of lung cancer treatment.

piRNA-36741 regulates BMP2-mediated osteoblast differentiation via METTL3 controlled m6A modification

The osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is essential for bone formation, and its imbalance can lead to bone diseases such as osteoporosis. It is reported that PIWI-interacting RNA-36741 (piR-36741) is up-regulated during the osteogenic differentiation, but its role in regulating osteogenic differentiation remains unclear. Here, the primary human BMSCs were used to induce osteogenic differentiation, and the expression of piR-36741 and METTL3 (methyltransferase like 3) was up-regulated during the osteogenic differentiation of BMSCs. Moreover, interference with piR-36741 or METTL3 markedly hindered the osteogenic differentiation of BMSCs, which was manifested by a reduction in osteoblast marker expression (including RUNX2, COL1A1, OPN and OCN), osteogenic phenotype and matrix mineralization. Mechanistically, the piR-36741-PIWIL4 complex directly interacted with METTL3 and prevented METTL3-mediated m6A modification of BMP2 mRNA transcripts, thereby promoting BMP2 expression. And overexpression of BMP2 reversed the inhibitory effect of piR-36741 silence on osteogenic differentiation and the Smad pathway activity. In addition, administration with piR-36741 mimic alleviated ovariectomy-induced osteoporosis in mice. In conclusion, piRNA-36741 overexpression promoted osteogenic differentiation of BMSCs and mitigated ovariectomy-induced osteoporosis through METTL3-mediated m6A methylation of BMP2 transcripts.

Piwi-Interacting RNAs: A New Class of Regulator in Human Breast Cancer

P-element-induced wimpy testis (Piwi)-interacting RNAs (piRNAs) are a class of germline-enriched small non-coding RNA that associate with Piwi family proteins and mostly induce transposon silencing and epigenetic regulation. Emerging evidence indicated the aberrant expression of Piwil proteins and associated piRNAs in multiple types of human cancer including breast cancer. Although the majority of piRNAs in breast cancer remains unclear of the function mainly due to the variety of regulatory mechanisms, the potential of piRNAs serving as biomarkers for cancer diagnosis and prognosis or therapeutic targets for cancer treatment has been demonstrated by in vitro and in vivo studies. Herein we summarized the research progress of oncogenic or tumor suppressing piRNAs and their regulatory mechanisms in regulating human breast cancer, including piR-021285, piR-823, piR-932, piR-36712, piR-016658, piR-016975 and piR-4987. The challenges and perspectives of piRNAs in the field of human cancer were discussed.

The biogenesis and biological function of PIWI-interacting RNA in cancer

Small non-coding RNAs (ncRNAs) are vital regulators of biological activities, and aberrant levels of small ncRNAs are commonly found in precancerous lesions and cancer. PIWI-interacting RNAs (piRNAs) are a novel type of small ncRNA initially discovered in germ cells that have a specific length (24-31 nucleotides), bind to PIWI proteins, and show 2'-O-methyl modification at the 3'-end. Numerous studies have revealed that piRNAs can play important roles in tumorigenesis via multiple biological regulatory mechanisms, including silencing transcriptional and posttranscriptional gene processes and accelerating multiprotein interactions. piRNAs are emerging players in the malignant transformation of normal cells and participate in the regulation of cancer hallmarks. Most of the specific cancer hallmarks regulated by piRNAs are involved in sustaining proliferative signaling, resistance to cell death or apoptosis, and activation of invasion and metastasis. Additionally, piRNAs have been used as biomarkers for cancer diagnosis and prognosis and have great potential for clinical utility. However, research on the underlying mechanisms of piRNAs in cancer is limited. Here, we systematically reviewed recent advances in the biogenesis and biological functions of piRNAs and relevant bioinformatics databases with the aim of providing insights into cancer diagnosis and clinical applications. We also focused on some cancer hallmarks rarely reported to be related to piRNAs, which can promote in-depth research of piRNAs in molecular biology and facilitate their clinical translation into cancer treatment.

Non-coding RNA in cancer

Majority of the human genome is transcribed to RNAs that do not encode proteins. These non-coding RNAs (ncRNAs) play crucial roles in regulating the initiation and progression of various cancers. Given the importance of the ncRNAs, the roles of ncRNAs in cancers have been reviewed elsewhere. Thus, in this review, we mainly focus on the recent studies of the function, regulatory mechanism and therapeutic potential of the ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), circular RNA (circRNA) and PIWI interacting RNA (piRNA), in different type of cancers.

Circulating SNORD57 rather than piR-54265 is a promising biomarker for colorectal cancer: common pitfalls in the study of somatic piRNAs in cancer

There is increasing interest among cancer researchers in the study of Piwi-interacting RNAs (piRNAs), a group of small RNAs important for maintaining genome stability in the germline. Aberrant expression of piRNAs in cancer could imply an involvement of these regulatory RNAs in neoplastic transformation. On top of that, it could enable early cancer diagnosis based on RNA analysis in liquid biopsies, as piRNAs are not expected to widely circulate in the bloodstream of healthy individuals. Indeed, it has recently been shown that serum piR-54265 allows for excellent discrimination between colorectal cancer patients and healthy controls. However, we have also shown that most somatic piRNAs reported to date in mammals are actually fragments of other noncoding RNAs. Herein, we show that reports positioning piR-54265 as a noninvasive biomarker for colorectal cancer were actually measuring variations in the levels of a full-length (72 nt) small nucleolar RNA in serum. This should place a cautionary note for future research in somatic and cancer-specific piRNAs. We deeply encourage this line of research but discuss proper ways to identify somatic piRNAs without the interference of erroneous entries contained in piRNA databases. We also introduce the concept of miscellaneous-piRNAs (m-piRNAs) to distinguish between canonical piRNAs and other small RNAs circumstantially associated with PIWI proteins in somatic cells.

Strategies for Targeting Gene Therapy in Cancer Cells With Tumor-Specific Promoters

Cancer is the second cause of death worldwide, surpassed only by cardiovascular diseases, due to the lack of early diagnosis, and high relapse rate after conventional therapies. Chemotherapy inhibits the rapid growth of cancer cells, but it also affects normal cells with fast proliferation rate. Therefore, it is imperative to develop other safe and more effective treatment strategies, such as gene therapy, in order to significantly improve the survival rate and life expectancy of patients with cancer. The aim of gene therapy is to transfect a therapeutic gene into the host cells to express itself and cause a beneficial biological effect. However, the efficacy of the proposed strategies has been insufficient for delivering the full potential of gene therapy in the clinic. The type of delivery vehicle (viral or non viral) chosen depends on the desired specificity of the gene therapy. The first gene therapy trials were performed with therapeutic genes driven by viral promoters such as the CMV promoter, which induces non-specific toxicity in normal cells and tissues, in addition to cancer cells. The use of tumor-specific promoters over-expressed in the tumor, induces specific expression of therapeutic genes in a given tumor, increasing their localized activity. Several cancer- and/or tumor-specific promoters systems have been developed to target cancer cells. This review aims to provide up-to-date information concerning targeting gene therapy with cancer- and/or tumor-specific promoters including cancer suppressor genes, suicide genes, anti-tumor angiogenesis, gene silencing, and gene-editing technology, as well as the type of delivery vehicle employed. Gene therapy can be used to complement traditional therapies to provide more effective treatments.

Regulatory effects of noncoding RNAs on the interplay of oxidative stress and autophagy in cancer malignancy and therapy

Noncoding RNAs (ncRNAs) regulation of various diseases including cancer has been extensively studied. Reactive oxidative species (ROS) elevated by oxidative stress are associated with cancer progression and drug resistance, while autophagy serves as an ROS scavenger in cancer cells. However, the regulatory effects of ncRNAs on autophagy and ROS in various cancer cells remains complex. Here, we explore how currently investigated ncRNAs, mainly miRNAs and lncRNAs, are involved in ROS production through modulating antioxidant genes. The regulatory effects of miRNAs and lncRNAs on autophagy-related (ATG) proteins to control autophagy activity in cancer cells are discussed. Moreover, differential expression of ncRNAs in tumor and normal tissues of cancer patients are further analyzed using The Cancer Genome Atlas (TCGA) database. This review hypothesizes links between ATG genes- or antioxidant genes-modulated ncRNAs and ROS production, which might result in tumorigenesis, malignancy, and cancer recurrence. A better understanding of the regulation of ROS and autophagy by ncRNAs might advance the use of ncRNAs as diagnostic and prognostic markers as well as therapeutic targets in cancer therapy.

Novel evidence for oncogenic piRNA-823 as a promising prognostic biomarker and a potential therapeutic target in colorectal cancer

piRNA‐823 as a member of the piRNA family is reported to promote tumour cell proliferation in multiple myeloma and hepatocellular cancer. However, few studies on the function of piRNA‐823 in colorectal cancer (CRC). Our present study data showed that piRNA‐823 plays an oncogene role in CRC cells. Inhibition of piRNA‐823 can significantly inhibit the proliferation, invasion and apoptosis resistance of CRC cells. Mechanism studies have shown that piRNA‐823 inhibits the ubiquitination of hypoxia‐inducible factor‐1 alpha (HIF‐1α) by up‐regulating the expression of Glucose‐6‐phosphate dehydrogenase (G6PD) and ultimately up‐regulates the glucose consumption of carcinoma cells and inhibits the content of intracellular reactive oxygen species (ROS). Therefore, we speculate piRNA‐823 promotes the proliferation, invasion and apoptosis resistance of CRC cells by regulating G6PD/HIF‐1α pathway. In this study, we set up the cancer‐promoting function recovery experiment of piRNA‐823 by silencing G6PD gene to confirm the dominance of the above‐mentioned pathways. Using clinical samples, we found that overexpression of piRNA‐823 correlated with poor overall survival and predicted a poor response to adjuvant chemotherapy of patients with CRC. In a word, our research has further enriched the theory of piRNA‐823 promoting the progression of CRC, and laid a solid foundation for the development of piRNA‐823‐based gene therapy for CRC and its use as a promising prognostic biomarker in CRC patients.