Long noncoding RNA PVT1 promotes metastasis via miR-484 sponging in osteosarcoma cells

lncRNA PVT1: a novel oncogene in multiple cancers

Long noncoding RNAs are involved in epigenetic gene modification, including binding to the chromatin rearrangement complex in pre-transcriptional regulation and to gene promoters in gene expression regulation, as well as acting as microRNA sponges to control messenger RNA levels in post-transcriptional regulation. An increasing number of studies have found that long noncoding RNA plasmacytoma variant translocation 1 (PVT1) plays an important role in cancer development. In this review of a large number of studies on PVT1, we found that PVT1 is closely related to tumor onset, proliferation, invasion, epithelial–mesenchymal transformation, and apoptosis, as well as poor prognosis and radiotherapy and chemotherapy resistance in some cancers. This review comprehensively describes PVT1 expression in various cancers and presents novel approaches to the diagnosis and treatment of cancer.

Prediction of Prognosis and Immunotherapy of Osteosarcoma Based on Necroptosis-Related lncRNAs

Background: Osteosarcoma (OS) is the most common primary tumor of bone in adolescents, and its survival rate is generally less than 20% when metastases occur. Necroptosis, a novel form of programmed necrotic cell death distinct from apoptosis, has been increasingly recognized as a promising therapeutic strategy. This study sought to identify long non-coding RNAs (lncRNAs) associated with necrotizing apoptosis to predict prognosis and target drug use to improve patient survival.

Methods: Transcriptomic data and clinical data from 85 OS patients with survival time data and expression profiles from 85 random normal adipose tissue samples were extracted from the UCSC Xena website (http://xena.ucsc.edu/). Nine necroptosis-associated differential prognostic lncRNAs were then identified by analysis of variance, correlation analysis, univariate Cox (uni-Cox) regression, and Kaplan–Meier analysis. Then, patients were randomized into training or testing groups. According to uni-Cox, we obtained prognostic lncRNAs in the training group and intersected them with the abovementioned nine lncRNAs to obtain the final necrotizing apoptosis–related differential prognostic lncRNAs (NRlncRNAs). Next, we performed the least absolute shrinkage and selection operator (LASSO) to construct a risk model of NRlncRNAs. Kaplan–Meier analysis, ROC curves, nomograms, calibration curves, and PCA were used to validate and evaluate the models and grouping. We also analyzed the differences in tumor immunity and drugs between risk groups.

Results: We constructed a model containing three NRlncRNAs (AL391121.1, AL354919.2, and AP000851.2) and validated its prognostic predictive power. The value of the AUC curve of 1-, 3-, and 5-year survival probability was 0.806, 0.728, and 0.731, respectively. Moreover, we found that the overall survival time of patients in the high-risk group was shorter than that in the low-risk group. GSEA and ssGSEA showed that immune-related pathways were mainly abundant in the low-risk group. We also validated the differential prediction of immune checkpoint expression, tumor immunity, and therapeutic compounds in the two risk groups.

Conclusion: Overall, NRlncRNAs have important functions in OS, and these three NRlncRNAs can predict the prognosis of OS and provide guidance for immunotherapy in OS.

CircPVT1: a pivotal circular node intersecting Long Non-Coding-PVT1 and c-MYC oncogenic signals

The role of circular RNAs in oncogenesis has begun to be widely studied in recent years, due to the significant impact that these molecules have in disease pathogenesis, as well as their potential for the future of innovative therapies. Moreover, due to their characteristically circular shape, circular RNAs are very resistant molecules to RNA degradation whose levels are easily assessed in body fluids. Accordingly, they represent an opportunity for the discovery of new diagnostic and prognostic markers in a wide range of diseases. Among circular RNAs, circPVT1 is a rather peculiar one that originates from the circularization of the exon 2 of the PVT1 gene that encodes a pro-tumorigenic long non-coding RNA named lncPVT1. There are a few examples of circular RNAs that derive from a locus producing another non-coding RNA. Despite their apparent transcriptional independence, which occurs using two different promoters, a possible synergistic effect in tumorigenesis cannot be excluded considering that both have been reported to correlate with the oncogenic phenotype. This complex mechanism of regulation appears to also be controlled by c-MYC. Indeed, the PVT1 locus is located only 53 Kb downstream c-MYC gene, a well-known oncogene that regulates the expression levels of about 15% of all genes. Here, we review circPVT1 origin and biogenesis highlighting the most important mechanisms through which it plays a fundamental role in oncogenesis, such as the well-known sponge activity on microRNAs, as well as its paradigmatic interactome link with lncPVT1 and c-MYC expression.

PVT1 and ZFAS1 lncRNAs expressions and their biomarker value in gastric cancer tissue sampling among Iranian population

BACKGROUND

lncRNAs are modulatory factors with critical function in the tumorigenesis pathways, introducing them as promising therapeutic and diagnostic biomarkers for different cancers. This study is thus aimed to evaluate the differences in PVT1 and ZFAS1 gene expression in tumorous tissues as compared with adjacent healthy non-tumorous biopsies of gastric cancer cases.

METHODS

One hundred two pairs of tumorous and adjacent non-tumorous biopsies of GC cases were sampled. RNA isolation and cDNA production were carried out. The qRT-PCR was performed to evaluate the expression of PVT1 and ZFAS1 genes. Moreover, the associations between PVT1 or ZFAS1 and clinicopathological characteristics as well as the biomarker roles of the lncRNAs were assessed.

RESULTS

The PVT1 and ZFAS1 expressions showed a significant increase and decrease in GC samples as compared with non-cancerous tissues, respectively. PVT1 expression was significantly associated with and lymph-node involvement (p = 0.0007). Moreover, ZFAS1 expression demonstrated a significant association with lymph-node involvement (p = 0.0005), and tumor size >5 cm (p = 0.003). The findings of the ROC curve revealed that PVT1 and ZFAS1 may act as a possible biomarker with AUC of 0.71 and 0.79, specificity of 78.43% and 79.41%, and sensitivity of 55.88% and 64.71%.

CONCLUSIONS

Regarding upregulation of PVT1 and downregulation of ZFAS1 in human GC samples, these genes may respectively act as oncogenic and tumor-suppressive factors in GC cases. Furthermore, PVT1 and ZFAS1 can be considered as possible biomarkers for the detection and treatment of GC cases.

Non-coding RNAs in necroptosis, pyroptosis and ferroptosis in cancer metastasis

Distant metastasis is the main cause of death for cancer patients. Recently, the newly discovered programmed cell death includes necroptosis, pyroptosis, and ferroptosis, which possesses an important role in the process of tumor metastasis. At the same time, it is widely reported that non-coding RNA precisely regulates programmed death and tumor metastasis. In the present review, we summarize the function and role of necroptosis, pyrolysis, and ferroptosis involving in cancer metastasis, as well as the regulatory factors, including non-coding RNAs, of necroptosis, pyroptosis, and ferroptosis in the process of tumor metastasis.

The Roles of ceRNAs-Mediated Autophagy in Cancer Chemoresistance and Metastasis

Simple Summary

Chemoresistance and metastasis are the main causes of treatment failure in cancers. Autophagy contribute to the survival and metastasis of cancer cells. Competing endogenous RNA (ceRNA), particularly long non-coding RNAs and circular RNA (circRNA), can bridge the interplay between autophagy and chemoresistance or metastasis in cancers via sponging miRNAs. This review aims to discuss on the function of ceRNA-mediated autophagy in the process of metastasis and chemoresistance in cancers. ceRNA network can sequester the targeted miRNA expression to indirectly upregulate the expression of autophagy-related genes, and thereof participate in autophagy-mediated chemoresistance and metastasis. Our clarification of the mechanism of autophagy regulation in metastasis and chemoresistance may greatly improve the efficacy of chemotherapy and survival in cancer patients. The combination of the tissue-specific miRNA delivery and selective autophagy inhibitors, such as hydroxychloroquine, is attractive to treat cancer patients in the future.

Abstract

Chemoresistance and metastasis are the main causes of treatment failure and unfavorable outcome in cancers. There is a pressing need to reveal their mechanisms and to discover novel therapy targets. Autophagy is composed of a cascade of steps controlled by different autophagy-related genes (ATGs). Accumulating evidence suggests that dysregulated autophagy contributes to chemoresistance and metastasis via competing endogenous RNA (ceRNA) networks including lncRNAs and circRNAs. ceRNAs sequester the targeted miRNA expression to indirectly upregulate ATGs expression, and thereof participate in autophagy-mediated chemoresistance and metastasis. Here, we attempt to summarize the roles of ceRNAs in cancer chemoresistance and metastasis through autophagy regulation.