Stem-cell protein Piwil2 is widely expressed in tumors and inhibits apoptosis through activation of Stat3/Bcl-XL pathway

Potentially diagnostic and prognostic roles of piRNAs/PIWIs in pancreatic cancer: A review

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive malignancy with limited early diagnostic methods and therapeutic options, contributing to its poor prognosis. Recent advances in high-throughput sequencing have highlighted the critical roles of noncoding RNAs (ncRNAs), particularly PIWI-interacting RNAs (piRNAs), in cancer biology. In this review, we systematically summarize the emerging roles of piRNAs and their associated PIWI proteins in PDAC pathogenesis, progression, and prognosis. We provide a comprehensive analysis of the molecular mechanisms by which piRNAs/PIWIs regulate gene expression and cellular signaling pathways in PDAC. Furthermore, we discuss their potential as novel biomarkers for early diagnosis and therapeutic targets. Importantly, this review identifies key piRNAs/PIWIs involved in PDAC and proposes innovative strategies for improving diagnosis and treatment outcomes. Our work not only consolidates current knowledge but also offers new perspectives for future research and clinical applications in PDAC management.

PIWIL2/PDK1 Axis Promotes the Progression of Cervical Epithelial Lesions via Metabolic Reprogramming to Maintain Tumor-Initiating Cell Stemness

When PIWIL2 expression is restored via heterogeneous integration of human papillomavirus, cellular reprogramming is initiated to form tumor-initiating cells (TICs), which triggers cervical squamous intraepithelial lesions (SIL). TIC stemness is critical for the prognosis of SIL. However, the mechanisms underlying TIC stemness maintenance and tumorigenicity remain unclear. Here, it is revealed that aberrant pyruvate dehydrogenase kinase 1 (PDK1) expression is closely related to aerobic glycolysis in SIL and poor survival in patients with cervical cancer. Mechanistically, that PIWIL2, which induced by stable transfection of either PIWIL2 or HPV16 oncogene E6 in human primary cervical basal epithelial cells and keratinocyte cell line HaCaT, upregulates PDK1 expression via the LIN28/let-7 axis, hence reprogramming metabolism to activate glycolysis and synchronize with TIC formation. It is further demonstrate that PDK1 is critical for TIC stemness maintenance and tumorigenicity via the PI3K/AKT/mTOR pathway both in vitro and in vivo, revealing a previously unclear mechanism for SIL progression, regression or relapse. Therefore, this findings suggest a potential rationale for prognostic predictions and selecting targeted therapy for cervical lesions.

Mechanisms Behind the Impact of PIWI Proteins on Cancer Cells: Literature Review

The P-Element-induced wimpy testis (PIWI) group of proteins plays a key role in RNA interference, particularly in the regulation of small non-coding RNAs. However, in recent years, PIWIs have gained attention in several diseases, mainly cancer. Therefore, the aim of this review was to evaluate current knowledge about the impact of PIWI proteins on cancer cells. PIWIs alter a number of pathways within cells, resulting in significant changes in cell behavior. Basic processes of cancer cells have been shown to be altered by either overexpression or inhibition of PIWIs. Regulation of apoptosis, metastasis, invasion, or proliferation of cancerous cells by these proteins proves their involvement in the progression of the malignancy. It has been revealed that PIWIs are also connected with cancer stem cells (CSCs), which proves their ability to become a therapeutic target. However, research on this topic is still fairly limited, and with significant differences between cancer types, it is necessary to refrain from making any decisive conclusions.

Short communication: Differential expression of piwi1 and piwi2 genes in tissues of tambacu and zebrafish: A possible relationship with the indeterminate muscle growth

Fish skeletal muscle is a component of the human diet, and understanding the mechanisms that control muscle growth can contribute to improving production in this sector and benefits the human health. In this sense, fish such as tambacu can represent a valuable source for exploring muscle growth regulators due to the indeterminate muscle growth pattern. In this context, the genes responsible for the indeterminate and determinate muscle growth pattern of fish are little explored, with piwi genes being possible candidates involved with these growth patterns. Piwi genes are associated with the proliferation and self-renewal of germ cells, and there are descriptions of these same functions in somatic cells from different tissues. However, little is known about the function of these genes in fish somatic cells. Considering this, our objective was to analyze the expression pattern of piwi 1 and 2 genes in cardiac muscle, skeletal muscle, liver, and gonad of zebrafish (species with determinate growth) and tambacu (species with indeterminate growth). We observed a distinct expression of piwi1 and piwi2 between tambacu and zebrafish, with both genes more expressed in tambacu in all tissues evaluated. Piwi genes can represent potential candidates involved with indeterminate muscle growth control.

Epstein-Barr virus reactivation induces divergent abortive, reprogrammed, and host shutoff states by lytic progression

Viral infection leads to heterogeneous cellular outcomes ranging from refractory to abortive and fully productive states. Single cell transcriptomics enables a high resolution view of these distinct post-infection states. Here, we have interrogated the host-pathogen dynamics following reactivation of Epstein-Barr virus (EBV). While benign in most people, EBV is responsible for infectious mononucleosis, up to 2% of human cancers, and is a trigger for the development of multiple sclerosis. Following latency establishment in B cells, EBV reactivates and is shed in saliva to enable infection of new hosts. Beyond its importance for transmission, the lytic cycle is also implicated in EBV-associated oncogenesis. Conversely, induction of lytic reactivation in latent EBV-positive tumors presents a novel therapeutic opportunity. Therefore, defining the dynamics and heterogeneity of EBV lytic reactivation is a high priority to better understand pathogenesis and therapeutic potential. In this study, we applied single-cell techniques to analyze diverse fate trajectories during lytic reactivation in three B cell models. Consistent with prior work, we find that cell cycle and MYC expression correlate with cells refractory to lytic reactivation. We further found that lytic induction yields a continuum from abortive to complete reactivation. Abortive lytic cells upregulate NFκB and IRF3 pathway target genes, while cells that proceed through the full lytic cycle exhibit unexpected expression of genes associated with cellular reprogramming. Distinct subpopulations of lytic cells further displayed variable profiles for transcripts known to escape virus-mediated host shutoff. These data reveal previously unknown and promiscuous outcomes of lytic reactivation with broad implications for viral replication and EBV-associated oncogenesis.

PIWI-interacting RNAs (PiRNAs) as emerging biomarkers and therapeutic targets in biliary tract cancers: A comprehensive review

Cancers affecting the biliary tract, such as gallbladder cancer and cholangiocarcinoma, make up a small percentage of adult gastrointestinal malignancies, but their incidence is on the rise. Due to the lack of dependable molecular biomarkers for diagnosis and prognosis, these cancers are often not detected until later stages and have limited treatment options. Piwi-interacting RNAs (piRNAs) are a type of small noncoding RNA that interacts with Piwi proteins and has been linked to various diseases, especially cancer. Manipulation of piRNA expression has the potential to serve as an important biomarker and target for therapy. This review uncovers the relationship between PIWI-interacting RNA (piRNA) and a variety of gastrointestinal cancers, including biliary tract cancer (BTC). It is evident that piRNAs have the ability to impact gene expression and regulate key genes and pathways related to the advancement of digestive cancers. Abnormal expression of piRNAs plays a significant role in the development and progression of digestive-related malignancies. The potential of piRNAs as potential biomarkers for diagnosis and prognosis, as well as therapeutic targets in BTC, is noteworthy. Nevertheless, there are obstacles and limitations that require further exploration to fully comprehend piRNAs' role in BTC and to devise effective diagnostic and therapeutic approaches using piRNAs. In summary, this review underscores the value of piRNAs as valuable biomarkers and promising targets for treating BTC, as we delve into the association between piRNAs and various gastrointestinal cancers, including BTC, and how piRNAs can impact gene expression and control essential pathways for digestive cancer advancement. The present research consists of a thorough evaluation presented in a storytelling style. The databases utilized to locate original sources were PubMed, MEDLINE, and Google Scholar, and the search was conducted using the designated keywords.

Epstein-Barr virus reactivation induces divergent abortive, reprogrammed, and host shutoff states by lytic progression

Viral infection leads to heterogeneous cellular outcomes ranging from refractory to abortive and fully productive states. Single cell transcriptomics enables a high resolution view of these distinct post-infection states. Here, we have interrogated the host-pathogen dynamics following reactivation of Epstein-Barr virus (EBV). While benign in most people, EBV is responsible for infectious mononucleosis, up to 2% of human cancers, and is a trigger for the development of multiple sclerosis. Following latency establishment in B cells, EBV reactivates and is shed in saliva to enable infection of new hosts. Beyond its importance for transmission, the lytic cycle is also implicated in EBV-associated oncogenesis. Conversely, induction of lytic reactivation in latent EBV-positive tumors presents a novel therapeutic opportunity. Therefore, defining the dynamics and heterogeneity of EBV lytic reactivation is a high priority to better understand pathogenesis and therapeutic potential. In this study, we applied single-cell techniques to analyze diverse fate trajectories during lytic reactivation in two B cell models. Consistent with prior work, we find that cell cycle and MYC expression correlate with cells refractory to lytic reactivation. We further found that lytic induction yields a continuum from abortive to complete reactivation. Abortive lytic cells upregulate NFκB and IRF3 pathway target genes, while cells that proceed through the full lytic cycle exhibit unexpected expression of genes associated with cellular reprogramming. Distinct subpopulations of lytic cells further displayed variable profiles for transcripts known to escape virus-mediated host shutoff. These data reveal previously unknown and promiscuous outcomes of lytic reactivation with broad implications for viral replication and EBV-associated oncogenesis.

HPV16 E6/E7-mediated regulation of PiwiL1 expression induces tumorigenesis in cervical cancer cells

PURPOSE

PiwiL1 has been reported to be over-expressed in many cancers. However, the molecular mechanism by which these proteins contribute to tumorigenesis and their regulation in cancer cells is still unclear. We intend to understand the role of PiwiL1 in tumorigenesis and also its regulation in cervical cells.

METHODS

We studied the effect of loss of PiwiL1 function on tumor properties of cervical cancer cells in vitro and in vivo. Also we have looked into the effect of PiwiL1 overexpression in the malignant transformation of normal cells both in vitro and in vivo. Further RNA-seq and RIP-seq analyses were done to get insight of the direct and indirect targets of PiwiL1 in the cervical cancer cells.

RESULTS

Here, we report that PiwiL1 is not only over-expressed, but also play a major role in tumor induction and progression. Abolition of PiwiL1 in CaSki cells led to a decrease in the tumor-associated properties, whereas, its upregulation conferred malignant transformation of normal HaCaT cells. Our study delineates a new link between HPV oncogenes, E6 and E7 with PiwiL1. p53 and E2F1 directly bind and differentially regulate PiwiL1 promoter in a context-dependant manner. Further, RNA-seq together with RIP-RNA-seq suggested a strong and direct role for PiwiL1 in promoting metastasis in cervical cancer cells.

CONCLUSION

Our study demonstrates that PiwiL1 act as an oncogene in cervical cancer by inducing tumor-associated properties and EMT pathway. The finding that HPV oncogenes, E6/E7 can positively regulate PiwiL1 suggests a possible mechanism behind HPV-mediated tumorigenesis in cervical cancer.

The potential value of cancer-testis antigens in ovarian cancer: Prognostic markers and targets for immunotherapy

BACKGROUND

Tumor immunotherapy has become an important adjuvant therapy after surgery, radiotherapy, and chemotherapy. In recent years, the role of tumor-associated antigen (TAA) in tumor immunotherapy has become increasingly prominent. Cancer-testis antigen (CTA) is a kind of TAA that is highly restricted in a variety of tumors and can induce an immune response.

AIMS

This review article aimed to evaluate the role of CTA on the progression of ovarian cancer, its diagnostic efficacy, and the potential for immunotherapy.

METHODS

We analyzed publications and outlined a comprehensive of overview the regulatory mechanism, immunogenicity, clinical expression significance, tumorigenesis, and application prospects of CTA in ovarian cancer, with a particular focus on recent progress in CTA-based immunotherapy.

RESULTS

The expression of CTA affects the occurrence, development, and prognosis of ovarian cancer and is closely related to tumor immunity.

CONCLUSION

CTA can be used as a biomarker for the diagnosis and prognosis evaluation of ovarian cancer and is an ideal target for antitumor immunotherapy. These findings provide novel insights on CTA in the improvement of diagnosis and treatment for ovarian cancer. The successes, current challenges and future prospects were also discussed to portray its significant potential.

Synergistic Immunoregulation: harnessing CircRNAs and PiRNAs to Amplify PD-1/PD-L1 Inhibition Therapy

The utilization of PD-1/PD-L1 inhibitors marks a significant advancement in cancer therapy. However, the efficacy of monotherapy is still disappointing in a substantial subset of patients, necessitating the exploration of combinational strategies. Emerging from the promising results of the KEYNOTE-942 trial, RNA-based therapies, particularly circRNAs and piRNAs, have distinguished themselves as innovative sensitizers to immune checkpoint inhibitors (ICIs). These non-coding RNAs, notable for their stability and specificity, were once underrecognized but are now known for their crucial roles in regulating PD-L1 expression and bolstering anti-cancer immunity. Our manuscript offers a comprehensive analysis of selected circRNAs and piRNAs, elucidating their immunomodulatory effects and mechanisms, thus underscoring their potential as ICIs enhancers. In conjunction with the recent Nobel Prize-awarded advancements in mRNA vaccine technology, our review highlights the transformative implications of these findings for cancer treatment. We also discuss the prospects of circRNAs and piRNAs in future therapeutic applications and research. This study pioneers the synergistic application of circRNAs and piRNAs as novel sensitizers to augment PD-1/PD-L1 inhibition therapy, demonstrating their unique roles in regulating PD-L1 expression and modulating immune responses. Our findings offer a groundbreaking approach for enhancing the efficacy of cancer immunotherapy, opening new avenues for treatment strategies. This abstract aims to encapsulate the essence of our research and the burgeoning role of these non-coding RNAs in enhancing PD-1/PD-L1 inhibition therapy, encouraging further investigation into this promising field.

Tumor Microenvironment Modulation by Cancer-Derived Extracellular Vesicles

The tumor microenvironment (TME) plays an important role in the process of tumorigenesis, regulating the growth, metabolism, proliferation, and invasion of cancer cells, as well as contributing to tumor resistance to the conventional chemoradiotherapies. Several types of cells with relatively stable phenotypes have been identified within the TME, including cancer-associated fibroblasts (CAFs), tumor-associated macrophages (TAMs), neutrophils, and natural killer (NK) cells, which have been shown to modulate cancer cell proliferation, metastasis, and interaction with the immune system, thus promoting tumor heterogeneity. Growing evidence suggests that tumor-cell-derived extracellular vesicles (EVs), via the transfer of various molecules (e.g., RNA, proteins, peptides, and lipids), play a pivotal role in the transformation of normal cells in the TME into their tumor-associated protumorigenic counterparts. This review article focuses on the functions of EVs in the modulation of the TME with a view to how exosomes contribute to the transformation of normal cells, as well as their importance for cancer diagnosis and therapy.

Critical appraisal of the piRNA-PIWI axis in cancer and cancer stem cells

Small noncoding RNAs play an important role in various disease states, including cancer. PIWI proteins, a subfamily of Argonaute proteins, and PIWI-interacting RNAs (piRNAs) were originally described as germline-specific molecules that inhibit the deleterious activity of transposable elements. However, several studies have suggested a role for the piRNA-PIWI axis in somatic cells, including somatic stem cells. Dysregulated expression of piRNAs and PIWI proteins in human tumors implies that, analogously to their roles in undifferentiated cells under physiological conditions, these molecules may be important for cancer stem cells and thus contribute to cancer progression. We provide an overview of piRNA biogenesis and critically review the evidence for the role of piRNA-PIWI axis in cancer stem cells. In addition, we examine the potential of piRNAs and PIWI proteins to become biomarkers in cancer.

Novel Perspectives for the Diagnosis and Treatment of Gynecological Cancers using Dysregulation of PIWI Protein and PiRNAs as Biomarkers

The term "gynecological cancer" is used for a group of cancers occurring in the female reproductive system. Some of these cancers are ranked as the leading causes of death in developed and developing countries. The lack of proper diagnostic strategies is one of the most important reasons that make them lethal. PIWI-interacting RNAs or piRNAs are a class of small non-coding RNAs, which contain 24-32 nucleotides. These RNAs take part in some cellular mechanisms, and their role in diverse kinds of cancer is confirmed by accumulative evidence. In this review, we gather some information on the roles of these RNAs and members of the PIWI protein family to provide new insight into accurate diagnostic biomarkers and more effective anti-cancer drugs with fewer side effects.

Arylsulfatase D is a prognostic biomarker that promotes glioma cells progression through JAK2/STAT3 pathway and M2 macrophage infiltration

Background

Arylsulfatase D (ARSD) belongs to the sulfatase family and plays a crucial role in maintaining the proper structure of bone and cartilage matrix. Although several researches have revealed the functions of ARSD in tumor progression, the prognostic value of ARSD in glioma and the related mechanisms have not been fully investigated.

Methods

We performed a pan-cancer analysis of ARSD, and investigated the relationship between expression of ARSD and overall survival (OS) in multiple glioma datasets. ROC curves and nomograms were created to investigate the predictive capacity of ARSD. Immune and analysis were conducted to investigate the mechanisms underlying the roles of ARSD in glioma. Glioma tissue samples were collected to verify the expression of ARSD in glioma, while the functions of ARSD were explored using cell experiment. M2 macrophage infiltration assay was used to determine the relation between ARSD and tumor immune microenvironment.

Results

Survival analysis indicated that individuals with high ARSD expression in glioma had a shorter survival time. Cox analysis showed that ARSD had a good ability for predicting prognosis in glioma. Immune analysis suggested that ARSD could regulate immune cell infiltration and affect the Cancer-Immunity Cycle to create an immunosuppressive environment. Combined with cell experiment and bioinformatic analysis, we found that ARSD can promote glioma progression through regulation of JAK2/STAT3 pathway and M2 macrophage infiltration.

Conclusion

Our study found that ARSD can promote glioma development by regulating immune microenvironment and JAK2/STAT3 signaling pathway, which provided a potential therapy target for glioma treatment.

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.

PLIC11 drives lung cancer progression through regulating the YY1/PIWIL4 axis

Lung cancer is the leading cause of cancer related deaths worldwide. Nonsmall cell lung cancers (NSCLC), the most common histological type of lung cancer, are known to be less well characterized. Long noncoding RNAs are a new class of cancer regulators. Here, we aimed to investigate the effect of lncRNA PLIC11 in NSCLC progression. In our study, we found that PLIC11 was upregulated in lung cancer, particularly in metastatic lung cancer tissues. Overexpression of PLIC11 enhanced cell proliferation, migration, and metastasis in vitro and in vivo. Mechanically, PLIC11 could interact with YY1 and promote PIWIL4 expression by transcription activation. Therefore, PLIC11 upregulation is a potential indicator of aggressive lung cancer, Silencing of PLIC11 has great potential therapeutic strategy in NSCLC.

The epigenetic regulatory mechanism of PIWI/piRNAs in human cancers

PIWI proteins have a strong correlation with PIWI-interacting RNAs (piRNAs), which are significant in development and reproduction of organisms. Recently, emerging evidences have indicated that apart from the reproductive function, PIWI/piRNAs with abnormal expression, also involve greatly in varieties of human cancers. Moreover, human PIWI proteins are usually expressed only in germ cells and hardly in somatic cells, so the abnormal expression of PIWI proteins in different types of cancer offer a promising opportunity for precision medicine. In this review, we discussed current researches about the biogenesis of piRNA, its epigenetic regulatory mechanisms in human cancers, such as N6-methyladenosine (m⁶A) methylation, histone modifications, DNA methylation and RNA interference, providing novel insights into the markers for clinical diagnosis, treatment and prognosis in human cancers.

Piwil2 (Mili) sustains neurogenesis and prevents cellular senescence in the postnatal hippocampus

Adult neural progenitor cells (aNPCs) ensure lifelong neurogenesis in the mammalian hippocampus. Proper regulation of aNPC fate has thus important implications for brain plasticity and healthy aging. Piwi proteins and the small noncoding RNAs interacting with them (piRNAs) have been proposed to control memory and anxiety, but the mechanism remains elusive. Here, we show that Piwil2 (Mili) is essential for proper neurogenesis in the postnatal mouse hippocampus. RNA sequencing of aNPCs and their differentiated progeny reveal that Mili and piRNAs are dynamically expressed in neurogenesis. Depletion of Mili and piRNAs in the adult hippocampus impairs aNPC differentiation toward a neural fate, induces senescence, and generates reactive glia. Transcripts modulated upon Mili depletion bear sequences complementary or homologous to piRNAs and include repetitive elements and mRNAs encoding essential proteins for proper neurogenesis. Our results provide evidence of a critical role for Mili in maintaining fitness and proper fate of aNPCs, underpinning a possible involvement of the piRNA pathway in brain plasticity and successful aging.

PIWIL2 Regulates the Proliferation, Apoptosis and Colony Formation of Colorectal Cancer Cell Line

Background

Tumor cells proliferation and apoptosis inhibition are the mechanisms through which the Colorectal Cancer (CRC) progression, metastasis and chemoresistance are promoted pathologically, offering clinical advantages for characterizing their molecular regulators.

Objectives

In this study, to unravel the role of PIWIL2 as a potential CRC oncogenic regulator, we examined the effect of its overexpression on proliferation, apoptosis and colony formation of SW480 colon cancer cell line.

Material and Methods

Established SW480-P (overexpression of PIWIL2) and SW480-control (SW480-empty vector) cell lines were cultured in DMEM containing 10% FBS with 1% penicillin-streptomycin. The total DNA and RNA was extracted for further experiments. Real-Time PCR and western blotting assay were performed to measure the differential expression of proliferation associated genes including the expression of cell cycle and anti-apoptotic genes as well as Ki-67 and PIWIL2 in both cell lines. Cell proliferation was determined using MTT assay, doubling time assay and the colony formation rate of transfected cells was measured with the 2D colony formation assay.

Results

At the molecular level, PIWIL2 overexpression was associated with significant up-regulation of cyclin D1, STAT3, BCL2-L1, BCL2-L2 and Ki-67 genes. MTT and doubling time assay showed that PIWIL2 expression induced time-related effects on proliferation rate of SW480 cells. Moreover, SW480-P cells had markedly greater capacity to form colonies.

Conclusions

PIWIL2 plays important roles to promote cancer cell proliferation and colonization via the cell cycle acceleration and inhibition of apoptosis, the mechanisms through which this gene seems to contribute to CRC development, metastasis and chemoresistance, hence potentially highlighting PIWIL2 targeted therapy as a valuable tool for CRC treatment.

Inhibitory Effects of Ursolic Acid on the Stemness and Progression of Human Breast Cancer Cells by Modulating Argonaute-2

The stemness and metastasis of cancer cells are crucial features in determining cancer progression. Argonaute-2 (AGO2) overexpression was reported to be associated with microRNA (miRNA) biogenesis, supporting the self-renewal and differentiation characteristics of cancer stem cells (CSCs). Ursolic acid (UA), a triterpene compound, has multiple biological functions, including anticancer activity. In this study, we find that UA inhibits the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines using the CCK-8 assay. UA induced a significant decrease in the fraction of CSC in which it was examined by changes in the expression of stemness biomarkers, including the Nanog and Oct4 genes. UA altered invasion and migration capacities by significant decreases in the levels of epithelial-to-mesenchymal transition (EMT) proteins of slug and vimentin. Furthermore, the co-reduction in oncogenic miRNA levels (miR-9 and miR-221) was a result of the down-modulation in AGO2 in breast cancer cells in vitro. Mechanically, UA increases PTEN expression to inactivate the FAK/PI3K/Akt/mTOR signaling pathway and the decreased level of c-Myc in quantitative RT-PCR and Western blot imaging analyses. Our current understanding of the anticancer potential of UA in interrupting between EMT programming and the state of CSC suggests that UA can contribute to improvements in the clinical practice of breast cancer.

Cytokine-mediated crosstalk between cancer stem cells and their inflammatory niche from the colorectal precancerous adenoma stage to the cancerous stage: Mechanisms and clinical implications

The majority of colorectal cancers (CRCs) are thought to arise from precancerous adenomas. Upon exposure to diverse microenvironmental factors, precancerous stem cells (pCSCs) undergo complex genetic/molecular changes and gradually progress to form cancer stem cells (CSCs). Accumulative evidence suggests that the pCSC/CSC niche is an inflammatory dominated milieu that contains different cytokines that function as the key communicators between pCSCs/CSCs and their niche and have a decisive role in promoting CRC development, progression, and metastasis. In view of the importance and increasing data about cytokines in modulating pCSCs/CSC stemness properties and their significance in CRC, this review summarizes current new insights of cytokines, such as interleukin (IL)-4, IL-6, IL-8, IL-17A, IL-22, IL-23, IL-33 and interferon (IFN)-γ, involving in the modulation of pCSC/CSC properties and features in precancerous and cancerous lesions and discusses the possible mechanisms of adenoma progression to CRCs and their therapeutic potential.

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.

Attenuation of Piwil2 induced by hypoxic postconditioning prevents cerebral ischemic injury by inhibiting CREB2 promoter methylation

Epigenetic modification contributes to the pathogenesis of cerebral ischemia. Piwil2 belongs to the PIWI proteins subfamily and has a key role in the regulation of gene transcription through epigenetics. However, the roles of Piwil2 in cerebral ischemia have not been investigated. In this study, we aim to elucidate the roles and the underlying molecular mechanisms of Piwil2 in ischemic tolerance induced by hypoxic postconditioning (HPC) against transient global cerebral ischemia (tGCI). We found that the expression of Piwil2 in CA1 was downregulated by HPC after tGCI. Silencing Piwil2 with antisense oligodeoxynucleotide (AS-ODN) in CA1 after tGCI decreased the expression of apoptosis-related proteins and exerted neuroprotective effects. Opposite results were observed after overexpression of Piwil2 induced by administration of Piwil2-carried lentivirus. Furthermore, we revealed differentially expressed Piwil2-interacting piRNAs in CA1 between HPC and tGCI groups by RNA binding protein immunoprecipitation (RIP) assay. Moreover, downregulating Piwil2 induced by HPC or AS-ODN after tGCI caused a marked reduction of DNA methyltransferase 3A (DNMT3A), which in turn abolished the tGCI-induced increase in the DNA methylation of cyclic AMP response element-binding 2 (CREB2), thus increasing mRNA and protein of CREB2. Finally, downregulating Piwil2 restored dendritic complexity and length, prevented the loss of dentritic spines, thereby improving cognitive function after tGCI. These data firstly reveal that Piwil2 plays an important part in HPC-mediated neuroprotection against cerebral ischemia through epigenetic regulation of CREB2.

Expression and biochemical significance of Piwil2 in stem cell lines

Introduction

P-element induced wimpy testis-like 2 (Piwil2) is in the Piwi gene family. Piwil2 has important roles in the self-renewal mechanism of stem cell induction and progression of numerous types of human malignancies such as lung, breast, colon, prostate, and cervical cancers. Glutathione S-transferase (GST) acts as detoxification in cancer metabolism. This study aimed to investigate the effects of the stem cell protein Piwil2 on MCF10A and MCF-7 at the GST activity levels.

Materials/Methods

MCF-7/Piwil2 and MCF10A/Piwil2, transfected with a plasmid carrying the Piwil2 gene, and non-transfected MCF-7 and MCF10A were cultured in a complete DMEM/F12 medium. GST A1 and P1 activity was determined in these cell lines using as substrates CDNB, EA respectively.

Results

According to experimental results, GST P1 activity decreased in the MCF-7/Piwil2 cells as compared with the non-transfected MCF-7 cells, however, MCF-7/Piwil2 cells demonstrated increases in GST A1 (total GST) activity. The statistically significant differences were found for the comparison of non-transfected MCF-7 and MCF-7/Piwil2 (p<0,0001), for GST enzyme activities by using CDNB and EA as substrates. These results were the same for the MCF10A cell line.

Discussion

It is shown for the first time that transfection studies may affect GST activity at the cellular mechanism level. The study contributes to determining the effect of transfection on GST isoenzymes and also how the Piwil2 gene may affect GST activity in the stem cell line.

Disorders and roles of tsRNA, snoRNA, snRNA and piRNA in cancer

Most small non-coding RNAs (sncRNAs) with regulatory functions are encoded by majority sequences in the human genome, and the emergence of high-throughput sequencing technology has greatly expanded our understanding of sncRNAs. sncRNAs are composed of a variety of RNAs, including tRNA-derived small RNA (tsRNA), small nucleolar RNA (snoRNA), small nuclear RNA (snRNA), PIWI-interacting RNA (piRNA), etc. While for some, sncRNAs' implication in several pathologies is now well established, the potential involvement of tsRNA, snoRNA, snRNA and piRNA in human diseases is only beginning to emerge. Recently, accumulating pieces of evidence demonstrate that tsRNA, snoRNA, snRNA and piRNA play an important role in many biological processes, and their dysregulation is closely related to the progression of cancer. Abnormal expression of tsRNA, snoRNA, snRNA and piRNA participates in the occurrence and development of tumours through different mechanisms, such as transcriptional inhibition and post-transcriptional regulation. In this review, we describe the research progress in the classification, biogenesis and biological function of tsRNA, snoRNA, snRNA and piRNA. Moreover, we emphasised their dysregulation and mechanism of action in cancer and discussed their potential as diagnostic and prognostic biomarkers or therapeutic targets.

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.

HIWI2 induces G2/M cell cycle arrest and apoptosis in human fibrosarcoma via the ROS/DNA damage/p53 axis

AIMS

Piwi, like RNA-mediated gene silencing 4 (PIWIL4) or HIWI2, are seen deregulated in human cancers and possibly play critical roles in tumorigenesis. It is unknown what role HIWI2 plays in the regulation of fibrosarcoma, an early metastatic lethal type of soft tissue sarcoma (STS). The present study aimed to investigate the role of HIWI2 in the tumorigenesis of fibrosarcoma.

MAIN METHODS

The expression of HIWI2 in HT1080 fibrosarcoma cells was determined by qRT-PCR and western blotting. The MTT assay, colony formation assay, cell cycle, and PE-AnnexinV/7AAD apoptosis assay using flow cytometry, DNA laddering assay, comet assay, and γH2AX accumulation assay were performed to study the effect of HIWI2 overexpression in HT1080 cells. Further, the effect of silencing of HIWI2 was determined by cell viability assay, transwell migration, and invasion assay.

KEY FINDINGS

HIWI2 is under-expressed in STS cell lines and tissues, which is associated with poor disease-free survival, disease-specific survival, and progression-free survival of the patients. Overexpression of HIWI2 in HT1080 cells causes DNA damage by increasing intracellular ROS by inhibiting the expression of antioxidant genes (SOD1, SOD2, GPX1, GPX4, and CAT). Furthermore, an increase in H2AX phosphorylation was observed, which activates p53 that promotes p21 expression and caspase-3 activation, leading to G2/M phase cell cycle arrest and apoptosis. HIWI2 silencing, on the contrary, promotes cell growth, migration, and invasion by activating MMP2 and MMP9.

SIGNIFICANCE

These results are the first to show that HIWI2 acts as a tumor suppressor in fibrosarcoma by modulating the ROS/DNA damage/p53 pathway.

Emerging roles and potential application of PIWI-interacting RNA in urological tumors

The piRNA (PIWI-interacting RNA) is P-Element induced wimpy testis (PIWI)-interacting RNA which is a small molecule, non-coding RNA with a length of 24-32nt. It was originally found in germ cells and is considered a regulator of germ cell function. It can interact with PIWI protein, a member of the Argonaute family, and play a role in the regulation of gene transcription and epigenetic silencing of transposable factors in the nucleus. More and more studies have shown that piRNAs are abnormally expressed in a variety of cancer tissues and patient fluids, and may become diagnostic tools, therapeutic targets, staging markers, and prognostic evaluation tools for cancer. This article reviews the recent research on piRNA and summarizes the structural characteristics, production mechanism, applications, and its role in urological tumors, to provide a reference value for piRNA to regulate urological tumors.

piRNA: A promising biomarker in early detection of gastrointestinal cancer

Gastrointestinal (GI) cancer has become the primary concern of today's society due to its aggressive nature and poor prognosis. PIWI-interacting RNAs (piRNAs), a subgroup of non-coding RNAs, are mainly expressed in the germline and have emerged as a critical regulator in gene expression and the epigenetic silencing of DNA transposable elements by interacting with PIWI proteins. piRNAs' dysregulations were reported to promote or suppress the initiation and development of different malignancies, especially gastrointestinal cancers. Recently, several studies suggested the use of piRNAs as potential cancer biomarkers associated with the progression and chemoresistance of GI cancer. Hence, this review article aims to focus on the role of piRNAs in GI cancer progression, metastasis, and their molecular mechanisms as therapeutic markers for GI cancer patients.

PIWI interacting RNAs perspectives: a new avenues in future cancer investigations

As a currently identified small non-coding RNAs (ncRNAs) category, the PIWI-interacting RNAs (piRNAs) are crucial mediators of cell biology. The human genome comprises over 30.000 piRNA genes. Although considered a new field in cancer research, the piRNA pathway is shown by the existing evidence as an active pathway in a variety of different types of cancers with critical impacts on main aspects of cancer progression. Among the regulatory molecules that contribute to maintaining the dynamics of cancer cells, the P-element Induced WImpy testis (PIWI) proteins and piRNAs, as new players, have not been broadly studied so far. Therefore, the identification of cancer-related piRNAs and the assessment of target genes of piRNAs may lead to better cancer prevention and therapy strategies. This review articleaimed to highlight the role and function of piRNAs based on existing data. Understanding the role of piRNA in cancer may provide perspectives on their applications as particular biomarker signature in diagnosis in early stage, prognosis and therapeutic strategies.

Non-Coding RNAs in Glioma Microenvironment and Angiogenesis

Glioma, especially glioblastoma, is the most common and lethal brain tumor. In line with the complicated vascularization processes and the strong intratumoral heterogeneity, tumor-associated blood vessels in glioma are regulated by multiple types of cells through a variety of molecular mechanisms. Components of the tumor microenvironment, including tumor cells and tumor-associated stromata, produce various types of molecular mediators to regulate glioma angiogenesis. As critical regulatory molecules, non-coding RNAs (ncRNAs) inside cells or secreted to the tumor microenvironment play essential roles in glioma angiogenesis. In this review, we briefly summarize recent studies about the production, delivery, and functions of ncRNAs in the tumor microenvironment, as well as the molecular mechanisms underlying the regulation of angiogenesis by ncRNAs. We also discuss the ncRNA-based therapeutic strategies in the anti-angiogenic therapy for glioma treatment.

P-element Induced WImpy protein-like RNA-mediated gene silencing 2 regulates tumor cell progression, apoptosis, and metastasis in oral squamous cell carcinoma

Objective

P-element Induced WImpy protein-like RNA-mediated gene silencing 2 (PIWIL2) is a reported oncogene strongly associated with tumorigenesis and cancer progression. However, the potential function of PIWIL2 in oral cancer is still largely unclear.

Methods

In this study, we investigated the clinical significance of PIWIL2 expression in human oral squamous cell carcinoma (OSCC) cell lines and tissues. We also examined its function in OSCC pathogenesis by knocking down PIWIL2 expression with short hairpin RNAs, followed by phenotypic experiments focused on cell migration, invasion, proliferation, and apoptosis rates.

Results

We found that PIWIL2 was overexpressed in OSCC cell lines and tissues and significantly correlated with the malignancy stage. Furthermore, knockdown of PIWIL2 in a human OSCC cell line Tca8113 induced cell cycle arrest and apoptosis. Silencing PIWIL2 expression also significantly suppressed the migration and invasion abilities of Tca8113 cells.

Conclusions

Collectively, our results suggest a functional role of PIWIL2 in regulating OSCC pathogenesis. Our data imply that PIWIL2 could serve as a potential therapeutic target for OSCC treatment.

PIWI-interacting RNAs: Mitochondria-based biogenesis and functions in cancer

PIWI-interacting RNA (piRNAs), once thought to be mainly functioning in germlines, are now known to play an essential role in somatic and cancerous tissues. Ping-pong cycle initiation and mitochondria-based phased production constitute the core of the piRNA biogenesis and these two processes are well conserved in mammals, including humans. By being involved in DNA methylation, histone marker deposition, mRNA degradation, and protein modification, piRNAs also contribute to carcinogenesis partly due to oncogenic stress-induced piRNA dysregulation. Also, piRNAs play important roles in cancer stemness, drug resistance, and tumor immunology. Results from liquid biopsy analysis of piRNA can be used in both cancer diagnoses and cancer prognoses. A combination of targeting piRNA with other therapeutic strategies could be groundbreaking cancer treatment.

CTR9-mediated JAK2/STAT3 pathway promotes the proliferation, migration, and invasion of human glioma cells

Background

CTR9 (Cln three requiring 9) has been reported to be implicated in protein modification and oncogenesis of several human cancers. However, the protein expression and mechanism of CTR9 in glioma progression remain unclear.

Methods

We analyzed mRNA expression of CTR9 and CTR9‐related survival curves in the public database. Then, we detected CTR9 expression in glioma tissues and constructed U251 and U87 cells with stable silencing or overexpression of CTR9. Cell function tests and Western blot were conducted to explore the effects of CTR9 on glioma proliferation, invasion and migration, and the specific mechanism. All the date was presented as means ± SEM. Two‐sample t test and one‐way analysis of variance (ANOVA) were used to identify whether there was a significant difference between each group of data.

Results

We found that CTR9 was overexpressed in glioma and inversely associated with glioma patient survival. The results manifested that knockdown of CTR9 suppressed the proliferation, migration, and invasion of glioma cells, while overexpression facilitated them. The underlying molecular mechanism may involve the regulation of JAK2/STAT3 pathway by CTR9.

Conclusion

Our present study indicates that CTR9 is highly expressed in glioma and related to glioma grading and prognosis. CTR9 regulates malignant behaviors of glioma cells by activating JAK2/STAT3 pathway. Therefore, CTR9 may be a promising biomarker for the targeted therapy and prognosis evaluation of glioma.

PIWI‑interacting RNA in cancer: Molecular mechanisms and possible clinical implications (Review)

PIWI‑interacting RNA is a class of non‑coding small RNA that is ~30 nt long and is primarily found in mammalian germ cells from mice and humans. In cooperation with the members of PIWI protein family, this macromolecule participates in germ cell development, inhibits DNA self‑-replication and maintains genomic stability. Increasing evidence has demonstrated that PIWI‑interacting RNA (piRNAs) are abnormally expressed in various human cancers, such as liver cancer, stomach cancer, colorectal cancer, osteosarcoma, breast cancer, lung cancer, prostate cancer, etc. piRNAs abnormal expression is also associated with the occurrence and development of human cancers, such as liver cancer, stomach cancer, colorectal cancer, etc. Despite their unclear molecular mechanisms, piRNAs may act as oncogenes or tumor suppressors by interacting with multiple cancer‑related signal pathways including STAT3/Bcl‑xl or coding genes, such as heat shock transcription factor‑1. Hence, piRNAs may be potential markers and targets and provide new opportunities for cancer diagnosis, treatment or prognosis monitoring. The current review mainly aims to highlight the latest research progress made in the biological functions and regulation of piRNAs in mammals, their involvement in various cancer forms and their potential clinical applications.

Epigenetic roles of PIWI proteins and piRNAs in colorectal cancer

Small non‐coding RNAs (sncRNAs) are a subgroup of non‐coding RNAs, with less than 200 nucleotides length and no potential for coding proteins. PiRNAs, a member of sncRNAs, were first discovered more than a decade ago and have attracted researcher’s attention because of their gene regulatory function both in the nucleus and in the cytoplasm. Recent investigations have found that the abnormal expression of these sncRNAs is involved in many human diseases, including cancers. Colorectal cancer (CRC), as a common gastrointestinal malignancy, is one of the important causes of cancer‐related deaths through the entire world and appears to be a consequence of mutation in the genome and epigenetic alterations. The aim of this review is to realize whether there is a relationship between CRC and piRNAs or not.

MAEL as a diagnostic marker for the early detection of esophageal squamous cell carcinoma

Background

Esophageal cancer is one of the most common malignancies among Iranians and is categorized as adenocarcinoma and squamous cell carcinoma. Various environmental and genetic factors are involved in this malignancy. Despite the recent advances in therapeutic modalities there is still a noticeable mortality rate among such patients which can be related to the late diagnosis. Regarding high ratio of esophageal squamous cell carcinoma (ESCC) in Iran, therefore it is required to assess molecular biology of ESCC to introduce novel diagnostic markers. In present study we assessed the role of Maelstrom (MAEL) cancer testis gene in biology of ESCC among Iranian patients.

Methods

Forty-five freshly normal and tumor tissues were enrolled to evaluate the levels of MAEL mRNA expression using Real time polymerase chain reaction.

Results

MAEL under and over expressions were observed in 12 (26.7%) and 9 (20%) of patients, respectively. MAEL fold changes were ranged between -4.33 to -1.87 (mean SD: -2.90± 0.24) and 1.92 to 7.72 (mean SD: 3.97± 0.69) in under and over expressed cases, respectively. There was a significant association between stage and MAEL expression in which majority of MAEL over expressed tumors (8/9, 88.9%) were in stage I/II (p<0.001). There was also a significant correlation between MAEL expression and depth of invasion in which tumor with T1/2 had higher levels of MAEL expression compared with T3/4 tumors (p=0.017). Moreover, there were significant correlations between MAEL expression, tumor size (p=0.028), and grade (p=0.003) among male patients.

Conclusions

Our data showed that the MAEL was mainly involved in primary stages of tumor progression and it has a declining expression levels toward the advanced stages and higher depth of tumor invasions. Therefore, MAEL can be efficiently introduced as an early detection marker among Iranian ESCC patients.

piRNA-823 Is a Unique Potential Diagnostic Non-Invasive Biomarker in Colorectal Cancer Patients

Early detection of colorectal cancer (CRC) is the most important factor in deciding its prognosis, so the need to develop an accurate screening test is a must. P-element induced wimpy testis (PIWI) RNA-823 (piR-823) is one of the first piRNAs recognized to be linked to malignancy. We aimed to investigate the expression levels of piR-823 in both serum and tissues of colorectal cancer patients and the ability to use its serum level as a non-invasive diagnostic biomarker to detect colorectal cancer. We determined piR-823 expression levels in 84 serum samples of CRC patients, 75 serum samples of healthy controls, and biological specimens obtained from the 84 patients with colorectal cancer from both the tumor tissues and the normal neighboring tissues using quantitative real-time reverse transcriptase-PCR. We showed that piR-823 had significantly higher serum and tissue expression levels in CRC patients compared to the controls. We observed a significant positive correlation between piR-823 serum levels and the staging of CRC, with significantly higher levels exhibiting advanced stages of CRC (III and IV). This translates into poorer differentiation and lymph node metastasis. The receiver operating characteristic curve (ROC curve) test showed 83.3% sensitivity and 89.3% specificity at a cut-off value of >5.98-fold change, with an area under the curve of 0.933 (p < 0.0001) concerning the ability of piR-823 in diagnosing patients with colorectal carcinoma. piR-823 expression is upregulated in colorectal cancer patients’ serum and tissues, and it can be used as a diagnostic noninvasive biomarker for CRC.

PIWIL2 interacting with IKK to regulate autophagy and apoptosis in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignancies and cause of death from cancer in China. Previous studies showed that autophagy and apoptosis inhibition are critical for the survival of ESCC cells. However, the underlying mechanisms remain to be clarified. Recently, we found that PIWIL2, a novel cancer testis protein, is highly expressed in ESCC and associated with high T-stage and poor 5-year survival rate in patients. Our further study showed that PIWIL2 can directly bind to IKK and promote its phosphorylation, leading to phosphorylation of IκB and subsequently nuclear translocation of NF-κB for apoptosis inhibition. Meanwhile, PIWIL2 competitively inhibits binding of IKK to TSC1, and thus deactivate mTORC1 pathway which suppresses ULK1 phosphorylation and initiation of autophagy. The mouse xenograft model suggested that PIWIL2 can promote ESCC growth in an IKK-dependent manner. This present work firstly revealed that PIWIL2 can play a role in regulating autophagy and apoptosis, and is associated with poor prognosis in ESCC patients, providing novel insights into the roles of PIWIL2 in tumorigenesis.

17-Allylamino-demethoxygeldanamycin Used Alone or in Combination with Sodium Orthovanadate Promotes Apoptosis and Inhibits Invasion of SH-SY5Y Cells by Modulating PIWIL2

Neuroblastoma (NB) is one of the most common extracranial solid tumors of childhood and accounts for 15% of cancer deaths. Even with the multimodality treatment protocols, the advanced-stage tumor overall 5-year survival rate is less than 50%. Therefore, novel drug therapy targeting cellular signal transduction pathways regulating the apoptotic cascade may be important for the treatment of drug-resistant NB. In our previous studies, we have demonstrated that 5 μM sodium orthovanadate (SOV) induced the apoptosis of SH-SY5Y cells. 17-Allylamino-demethoxygeldanamycin (17-AAG) is a geldanamycin- (GA-) derived heat shock protein 90 (Hsp90) inhibitor, and it has been shown to have potent antitumor activity in head and neck cancers. However, the effect of 17-AAG on the apoptosis of NB cells has not been reported. Therefore, the purpose of this study was to determine the effects of 17-AAG and SOV on the growth and invasion of SH-SY5Y cells in vitro and explore the related mechanism. In this study, we first investigated the antiviability effect of 17-AAG on SH-SY5Y cells, then studied the cell apoptosis and invasion influenced by 17-AAG and SOV, and assessed the role of PIWI-Like2 (PIWIL2) and piRNA-PIWI signaling in it. The results showed that 5 μM 17-AAG inhibited cell growth and viability and induced apoptosis in SH-SY5Y cells. Both 17-AAG and SOV reduced the level of PIWIL2 and Bcl-xl proteins and inhibited the invasion of SH-SY5Y cells. In addition, the combined use of the two drugs had greater effect than the single use of any drug.

PIWI-Like 1 and PIWI-Like 2 Expression in Breast Cancer

Simple Summary

A family of proteins, the PIWI proteins, play a crucial role in the regulation of the development of germ cells and self-preservation of so-called stem cells. Former studies have shown that these proteins can be over- or underrepresented (over-/underexpressed) in some cancers and, in the case of abnormal expression, may be correlated with worse outcomes of tumor patients. In our study, we investigated the influence of the two PIWI proteins, PIWI-like 1 and PIWI-like 2, on the survival of breast cancer patients and their correlation with certain breast cancer subtypes. If a breast cancer showed a higher expression of PIWI-like 1 protein but less PIWI-like 2 protein than in non-tumorous tissue, the patient suffered from a more aggressive breast cancer subtype and had shorter survival. By analyzing these two proteins in breast cancer, we were able to predict tumor aggressiveness and prognosis.

Abstract

PIWI-like 1 and PIWI-like 2 play a role in stem cell self-renewal, and enhanced expression has been reported for several tumor entities. However, few studies have investigated PIWI-like 1 and PIWI-like 2 expressions in breast cancer subtypes regarding prognosis. Therefore, we examined protein expression in a large consecutive cohort of breast cancer patients and correlated it to breast cancer subtypes and survival outcome. PIWI-like 1 and PIWI-like 2 expressions were evaluated using immunohistochemistry in a cohort of 894 breast cancer patients, of whom 363 were eligible for further analysis. Percentage and intensity of stained tumor cells were analyzed and an immunoreactive score (IRS) was calculated. The interaction of PIWI-like 1 and PIWI-like 2 showed a prognostic effect on survival. For the combination of high PIWI-like 1 and low PIWI-like 2 expressions, adjusted hazard ratios (HRs) were significantly higher with regard to overall survival (OS) (HR 2.92; 95% confidence interval (CI) 1.24, 6.90), disease-free survival (DFS) (HR 3.27; 95% CI 1.48, 7.20), and distant disease-free survival (DDFS) (HR 7.64; 95% CI 2.35, 24.82). Both proteins were significantly associated with molecular-like and PAM50 subgroups. Combining high PIWI-like 1 and low PIWI-like 2 expressions predicted poorer prognosis and both markers were associated with aggressive molecular subtypes.

An insight into the roles of piRNAs and PIWI proteins in the diagnosis and pathogenesis of oral, esophageal, and gastric cancer

P-Element induced wimpy testis (PIWI)-interacting RNA (piRNA) is a member of the non-coding RNAs family. Four PIWI proteins are found to be expressed in humans. The number of studies focusing on the roles of piRNAs and PIWI proteins in the field of cancer is increasing. Oral, esophageal, and gastric cancers are considered as important causes of death. PIWI proteins and piRNAs are suggested to be involved in the pathogenesis of these diseases. Thus, studying these molecules may be beneficial for finding new therapeutics. Since it is shown that currently used biomarkers for these cancers have low sensitivity and specificity, there is a necessity for identifying novel non-invasive biomarkers which are highly sensitive and specific. This paper will provide an insight into current knowledge about the functions of PIWI proteins and piRNAs in the oral, esophageal, and gastric cancer. We discuss how PIWI proteins and piRNAs can be involved in the pathogenesis of these cancers. Moreover, we review the studies concerning with the roles of PIWI proteins and piRNAs as biomarkers which are used for diagnostic and prognostic purposes.

PIWIL1 promotes gastric cancer via a piRNA-independent mechanism

Targeted cancer therapy aims to achieve specific elimination of cancerous but not normal cells. Recently, PIWI proteins, a subfamily of the PAZ-PIWI domain (PPD) protein family, have emerged as promising candidates for targeted cancer therapy. PPD proteins are essential for small noncoding RNA pathways. The Argonaute subfamily partners with microRNA and small interfering RNA, whereas the PIWI subfamily partners with PIWI-interacting RNA (piRNA). Both PIWI proteins and piRNA are mostly expressed in the germline and best known for their function in transposon silencing, with no detectable function in mammalian somatic tissues. However, PIWI proteins become aberrantly expressed in multiple types of somatic cancers, thus gaining interest in targeted therapy. Despite this, little is known about the regulatory mechanism of PIWI proteins in cancer. Here we report that one of the four PIWI proteins in humans, PIWIL1, is highly expressed in gastric cancer tissues and cell lines. Knocking out the PIWIL1 gene (PIWIL1-KO) drastically reduces gastric cancer cell proliferation, migration, metastasis, and tumorigenesis. RNA deep sequencing of gastric cancer cell line SNU-1 reveals that KO significantly changes the transcriptome, causing the up-regulation of most of its associated transcripts. Surprisingly, few bona fide piRNAs exist in gastric cancer cells. Furthermore, abolishing the piRNA-binding activity of PIWIL1 does not affect its oncogenic function. Thus, PIWIL1 function in gastric cancer cells is independent of piRNA. This piRNA-independent regulation involves interaction with the UPF1-mediated nonsense-mediated mRNA decay (NMD) mechanism. Altogether, our findings reveal a piRNA-independent function of PIWIL1 in promoting gastric cancer.

Biological roles of piRNAs in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies worldwide and a major cause of cancer-related deaths. Numerous studies have suggested that piwi-interacting RNAs (piRNAs), a new type of non-coding RNA (ncRNA), are closely related to the occurrence and development of cancer. piRNAs have been shown to regulate the occurrence of CRC by modulating multiple molecular signaling pathways. Here, the roles of piRNAs in CRC were reviewed to provide evidence for their potential as molecular targets for CRC.

Cyclin D1 promotes secretion of pro-oncogenic immuno-miRNAs and piRNAs

The molecular mechanisms governing the secretion of the non-coding genome are poorly understood. We show herein that cyclin D1, the regulatory subunit of the cyclin-dependent kinase that drives cell-cycle progression, governs the secretion and relative proportion of secreted non-coding RNA subtypes (miRNA, rRNA, tRNA, CDBox, scRNA, HAcaBox. scaRNA, piRNA) in human breast cancer. Cyclin D1 induced the secretion of miRNA governing the tumor immune response and oncogenic miRNAs. miR-21 and miR-93, which bind Toll-Like Receptor 8 to trigger a pro-metastatic inflammatory response, represented >85% of the cyclin D1-induced secreted miRNA transcripts. Furthermore, cyclin D1 regulated secretion of the P-element Induced WImpy testis (PIWI)-interacting RNAs (piRNAs) including piR-016658 and piR-016975 that governed stem cell expansion, and increased the abundance of the PIWI member of the Argonaute family, piwil2 in ERα positive breast cancer. The cyclin D1-mediated secretion of pro-tumorigenic immuno-miRs and piRNAs may contribute to tumor initiation and progression.

PIWIL2 is overexpressed in adenomyotic lesions of women with diffuse adenomyosis

PURPOSE

Adenomyosis has been studied throughout the years, however, its aetiology and physiopathology are still unknown. The aim of this study was to identify the presence of PIWI proteins in women with adenomyosis.

METHODS

We included 72 participants to be part of this study and were divided into two groups based on their anatomopathological diagnosis, control (n = 36) or adenomyosis (n = 36). All samples were tested for PIWIL1, PIWIL2 and PIWIL4 proteins by immunohistochemistry. The evaluation of protein expression was performed by the digital histological score (DHSCORE) and by the pathologist's analysis.

RESULTS

The participants had a mean age of 44.28 ± 5.76 years and 45.81 ± 4.86 years in the control and adenomyosis groups, respectively (p ≥ 0.05). Other clinical characteristics of the participants showed no statistical difference as well. PIWIL2 is highly expressed in the adenomyosis in comparison to the control group (p = 0.0001). The PIWIL1 is downregulated in the adenomyosis (p = 0.003) and PIWIL4 showed no difference in its expression (p = 0.05).

CONCLUSION

PIWIL2 might be involved in cellular survival and PIWIL1 may be downregulated due to the loss of tissue's function and response to the hostile environment of the myometrium. This is the first time that PIWI proteins are studied in the adenomyosis.

Derivation of oocyte-like cells from putative embryonic stem cells and parthenogenetically activated into blastocysts in goat

Germ cells are responsible for the propagation of live animals from generation to generation, but to surprise, a steep increase in infertile problems among livestock poses great threat for economic development of human race. An alternative and robust approach is essential to combat these ailments. Here, we demonstrate that goat putative embryonic stem cells (ESCs) were successfully in vitro differentiated into primordial germ cells and oocyte-like cells using bone morphogenetic protein-4 (BMP-4) and trans-retinoic acid (RA). Oocyte-like cells having distinct zonapellucida recruited adjacent somatic cells in differentiating culture to form cumulus-oocyte complexes (COCs). The putative COCs were found to express the zonapellucida specific (ZP1 and ZP2) and oocyte-specific markers. Primordial germ cell-specific markers VASA, DAZL, STELLA, and PUM1 were detected at protein and mRNA level. In addition to that, the surface architecture of these putative COCs was thoroughly visualized by the scanning electron microscope. The putative COCs were further parthenogenetically activated to develop into healthy morula, blastocysts and hatched blastocyst stage like embryos. Our findings may contribute to the fundamental understanding of mammalian germ cell biology and may provide clinical insights regarding infertility ailments.

PIWIL-2 and piRNAs are regularly expressed in epithelia of the skin and their expression is related to differentiation

PIWI proteins play multiple roles in germline stem cell maintenance and self-renewal. PIWI-interacting RNAs (piRNAs) associate with PIWI proteins, form effector complexes and maintain genome integrity and function in the regulation of gene expression by epigenetic modifications. Both are involved in cancer development. In this study, we investigated the expression of PIWIL-2 and piRNAs in normal human skin and epithelial tumors and its regulation during keratinocyte (KC) differentiation. Immunohistochemistry showed that PIWIL-2 was regularly expressed in the epidermis and adnexal tissue with strongest expression in sebaceous glands. Cell culture studies revealed an association of PIWIL-2 expression with the state of differentiated KC. In contrast, the PIWIL-2 expression pattern did not correlate with stem cell compartments or malignancy. piRNAs were consistently detected in KC in vitro by next-generation sequencing and the expression levels of numerous piRNAs were regulated during KC differentiation. Epidermal piRNAs were predominantly derived from processed snoRNAs (C/D-box snoRNAs), tRNAs and protein coding genes. Our data indicate that components of the PIWIL-2-piRNA pathway are present in epithelial cells of the skin and are regulated in the context of KC differentiation, suggesting a role of somatic gene regulation. However, putative roles in the maintenance of stem cell compartments or the development of malignancy in the skin were not supported by this study.