High-throughput sequencing of circRNAs reveals novel insights into mechanisms of nigericin in pancreatic cancer

The expression profiles of circular RNAs and competing endogenous RNA networks in intrahepatic cholangiocarcinoma

Introduction: Intrahepatic cholangiocarcinoma (iCCA) is a heterogeneous entity with diverse etiologies, morphologies, and clinical outcomes, but our knowledge of its epidemiology and carcinogenesis is very limited. Materials and methods: The expression patterns of circRNAs were explored in iCCA tissues and corresponding adjacent normal ones, denoted by (iCCA) and (iCCAP), respectively, using high-throughput sequencing. Results: A total of 117 differential expressed (DE) circRNAs were identified. Based on the parental transcripts of circRNAs, these DE circRNAs were related to several important GO terms and were enriched in important pathways. Two circRNA-mediated ceRNA networks were constructed and many important metabolic pathways related to mRNAs were regulated by DE circRNAs via miRNAs. Conclusion: Our study revealed the DE circRNAs in the iCCA tissues compared with iCCAP ones, suggesting that circRNAs may play crucial roles in the pathogenesis of iCCA.

Evidence of Metallic and Polyether Ionophores as Potent Therapeutic Drug Candidate in Cancer Management

Cancer remains one of the most crucial human malignancies with a higher mortality rate globally, and is predicted to escalate soon. Dysregulated ion homeostasis in cancerous cells prompted the researchers to investigate further ion homeostasis impeding agents as potent anticancerous agents. Reutilization of FDA-approved non-cancerous drugs has emerged as a practical approach to developing potent, cost-effective drugs for cancer treatment. Across the globe, most nations are incapable of fulfilling the medical demands of cancer patients due to costlier cancerous drugs. Therefore, we have inclined our review towards emphasizing recent advancements in cancer therapies involving ionophores utilization in exploring potent anticancer drugs. Numerous research reports have established the significant anticancerous potential of ionophores in several pre-clinical reports via modulating aberrant cell signaling pathways and enhancing antitumor immunity in immune cells. This review has mainly summarized the most significant ion homeostasis impeding agents, including copper, zinc, calcium, and polyether, that presented remarkable potential in cancer therapeutics via enhanced antitumor immunity and apoptosis induction. Altogether, this study could provide a robust future perspective for developing cost-effective anticancerous drugs rapidly and cost-effectively, thereby combating the limitations of currently available drugs used in cancer treatment.

Biological functions, mechanisms, and clinical significance of circular RNA in pancreatic cancer: a promising rising star

Pancreatic cancer (PC) is a highly malignant solid tumor with insidious onset and easy early metastasis. Despite tremendous efforts devoted to research in this field, the mechanisms underlying PC tumorigenesis and progression remain unclear. Additionally, robust biomarkers and satisfactory therapeutic strategies for clinical use in PC patients are still lacking. Circular RNAs (circRNAs) are a new type of non-coding RNA originating from precursor messenger RNAs, with a covalent continuous closed-loop structure, strong stability and high specificity. Accumulating evidence suggests that circRNAs may participate in PC development and progression. Abnormal expression of circRNAs in PC is considered a vital factor that affects tumor cell proliferation, migration, invasion, apoptosis, angiogenesis and drug resistance. In this review of relevant articles published in recent years, we describe the basic knowledge concerning circRNAs, including their classification, biogenesis, functions and research approaches. Moreover, the biological roles and clinical significance of circRNAs related to PC are discussed. Finally, we note the questions remaining from recent studies and anticipate that further investigations will address these gaps in knowledge in this field. In conclusion, we expect to provide insights into circRNAs as potential targets for specific PC diagnosis and treatment in the future.

PRKAR2A-derived circular RNAs promote the malignant transformation of colitis and distinguish patients with colitis-associated colorectal cancer

BACKGROUND

Emerging studies have proved that colonic inflammation caused by refractory inflammatory bowel disease (IBD) can initiate the colitis-associated cancer (CAC), but the transition from inflammation to carcinoma is still largely unknown.

METHODS

In this study, mouse colitis and CAC models were established, and the RNA-seq by circRNA microarray was employed to identify the differentially expressed circRNAs and mRNAs in different comparisons (DSS vs. NC and AOM/DSS vs. DSS). The bioinformatics analyses were used to search the common characteristics in mouse colitis and CAC.

RESULTS

The K-means clustering algorithm packaged these differential expressed circRNAs into subgroup analysis, and the data strongly implied that mmu_circ_0001109 closely correlated to the pro-inflammatory signals, while mmu_circ_0001845 was significantly associated with the Wnt signalling pathway. Our subsequent data in vivo and in vitro confirmed that mmu_circ_0001109 could exacerbate the colitis by up-regulating the Jak-STAT3 and NF-kappa B signalling pathways, and mmu_circ_0001845 promoted the CAC transformation through the Wnt signalling pathway. By RNA blasting between mice and humans, the human RTEL1- and PRKAR2A-derived circRNAs, which might be considered as homeotic circRNAs of mmu_circ_0001109 and mmu_circ_0001845, respectively, were identified. The clinical data revealed that RTEL1-derived circRNAs had no clinical significance in human IBD and CAC. However, three PRKAR2A-derived circRNAs, which had the high RNA similarities to mmu_circ_0001845, were remarkably up-regulated in CAC tissue samples and promoted the transition from colitis to CAC.

CONCLUSIONS

Our results suggested that these human PRKAR2A-derived circRNAs could be novel candidates for distinguishing CAC patients and predicted the prognosis of CAC.

Downregulation of hsa_circRNA_0001400 Helps to Promote Cell Apoptosis Through Disruption of the circRNA_0001400-miR-326 Sponge in Cervical Cancer Cells

Background: In recent years, circular RNAs (circRNAs) have been reported to serve as essential regulators in several human cancers. Nevertheless, the function and mechanism of circRNAs in cervical cancer remain elusive. Methods: Flow cytometry assays were performed to measure cell apoptosis and cell cycle. Colony Formation and transwell chamber were performed to measure cell migration and invasion. Double luciferase reporter for gene analysis was used to detect the interaction between hsa-circRNA_0001400, miR-326, and Akt. Relative protein levels were determined by immunoblotting and relative gene levels were determined by quantitative real-time PCR. Tumor Xenograft Modeling was used to evaluate the effect of hsa_circRNA_0001400_siRNA in vivo. Results: In the present study, we showed that hsa_circRNA_0001400 was highly expressed in cervical cancer tissues relative to in matched normal tissue. We found that hsa_circRNA_0001400_siRNA significantly promoted the apoptosis of cervical cancer cells and arrested the cell cycle and migration of cervical cancer cells. We showed that hsa_circRNA_0001400_siRNA can inhibit the protein expression of Akt and that the inhibition of miR-326 could rescue the inhibition of Akt in cervical cancer cells. We found that has-miR-326 was downregulated in cervical cancer tissues and hsa_circRNA_0001400_siRNA could increase the gene expression of has-miR-326. We also observed that hsa_circRNA_0001400_siRNA inhibited the growth and angiogenesis of SiHa xenografts in nude mice. Conclusion: In conclusion, this study provides evidence that the hsa_circRNA_0001400-miR-326-Akt network promotes cervical cancer progression. Notably, our findings demonstrate the novel antitumor effects of hsa_circRNA_0001400_siRNA in cervical cancer.

MicroRNA‑190b expression predicts a good prognosis and attenuates the malignant progression of pancreatic cancer by targeting MEF2C and TCF4

MicroRNAs (miRNAs/miRs) are key components of regulatory networks in cancer. Although miR-190b is an important tumor-related miRNA, its role in pancreatic cancer has not been extensively investigated. The aim of the present study was to examine the expression of miR-190b in pancreatic cancer cell lines and tissues and evaluate its effects on cancer progression. Reverse transcription-quantitative PCR (RT-qPCR) analysis was used to measure miR-190b expression levels in human pancreatic cancer cell lines and tissues, and the association between miR-190b expression and clinicopathological characteristics was assessed. An in vitro Transwell invasion assay and an in vivo metastasis formation assay were performed using pancreatic cancer cells. The effect of miR-190b on pancreatic cancer cell proliferation was evaluated using a Cell Counting Kit-8 assay based on an in vivo xenograft mouse model. The direct targets of miR-190b were predicted using bioinformatics tools and were validated through western blotting and luciferase reporter assays. Pancreatic cancer cell lines and tissues were found to express lower levels of miR-190b compared with normal cells and adjacent non-tumor tissues. Furthermore, high expression of miR-190b was found to be positively correlated with low T, N and American Joint Committee on Cancer classifications, and predicted a good prognosis. miR-190b was shown to exert suppressive effects on cancer cell proliferation, invasion and metastasis. In addition, it was also found that miR-190b directly targeted myocyte enhancer factor 2C (MEF2C) and transcription factor 4 (TCF4) in pancreatic cancer, thus serving as a tumor suppressor and a predictor of good prognosis in pancreatic cancer. The immunohistochemistry and RT-qPCR results indicated that the MEF2C and TCF4 expression levels were negatively correlated with the miR-190b expression levels. The findings of the present study highlight the value of miR-190b as a novel target candidate for pancreatic cancer diagnosis and therapy.

Non-Coding RNAs in Pancreatic Cancer Diagnostics and Therapy: Focus on lncRNAs, circRNAs, and piRNAs

Simple Summary

Pancreatic cancer is the seventh leading cause of cancer related death worldwide. In the United States, pancreatic cancer remains the fourth leading cause of cancer related death. The lack of early diagnosis and effective therapy contributes to the high mortality of pancreatic cancer. Therefore, there is an urgent need to find novel and effective biomarkers for the diagnosis and treatment of pancreatic cancer. Long noncoding RNA, circular RNAs and piwi-interacting RNA are non-coding RNAs and could become new biomarkers for the diagnosis, prognosis, and treatment of pancreatic cancer. We summarize the new findings on the roles of these non-coding RNAs in pancreatic cancer diagnosis, prognosis and targeted therapy.

Abstract

Pancreatic cancer is an aggressive malignance with high mortality. The lack of early diagnosis and effective therapy contributes to the high mortality of this deadly disease. For a long time being, the alterations in coding RNAs have been considered as major targets for diagnosis and treatment of pancreatic cancer. However, with the advances in high-throughput next generation of sequencing more alterations in non-coding RNAs (ncRNAs) have been discovered in different cancers. Further mechanistic studies have demonstrated that ncRNAs such as long noncoding RNAs (lncRNA), circular RNAs (circRNA) and piwi-interacting RNA (piRNA) play vital roles in the regulation of tumorigenesis, tumor progression and prognosis. In recent years, increasing studies have focused on the roles of ncRNAs in the development and progression of pancreatic cancer. Novel findings have demonstrated that lncRNA, circRNA, and piRNA are critically involved in the regulation of gene expression and cellular signal transduction in pancreatic cancer. In this review, we summarize the current knowledge of roles of lncRNA, circRNA, and piRNA in the diagnosis and prognosis of pancreatic cancer, and molecular mechanisms underlying the regulation of these ncRNAs and related signaling in pancreatic cancer therapy. The information provided here will help to find new strategies for better treatment of pancreatic cancer.

Identification of Enzalutamide Resistance-Related circRNA-miRNA-mRNA Regulatory Networks in Patients with Prostate Cancer

Purpose

This study aimed to identify enzalutamide resistant-related (EnzR-related) circRNAs and to characterize and validate circRNA-miRNA-mRNA ceRNA regulatory network and corresponding prognostic signature of prostate cancer patients.

Methods

We obtained circRNA expression microarray from the Gene Expression Omnibus (GEO) database and performed differential expression analysis to identify EnzR-related circRNAs using the limma package. The miRNA and mRNA expression profiling were downloaded and performed differential expression analysis, then overlapped with predicted candidates. Next, we established circRNA-miRNA-mRNA ceRNA network and PPI network utilized Cytoscape software and STRING database, respectively. In addition, univariate and Lasso Cox regression analyses were applied to generate a prognostic signature. Receiver operating characteristic (ROC) curves and Kaplan–Meier analysis were used to evaluate the reliability and sensitivity of the signature. Ultimately, we chose hsa_circ_0047641 to validate the feasibility of the EnzR-related ceRNA regulatory pathway using qRT-PCR, CCK8 and Transwell assays.

Results

We identified 13 EnzR-related circRNAs and constructed a ceRNA regulatory network that contained two downregulated circRNAs (has-circ-00000919 and has-circ-0000036) and two upregulated circRNAs (has-circ-0047641 and has-circ-0068697), and their sponged 6 miRNAs and 167 targeted mRNAs. Subsequently, these targeted mRNAs were performed to implement PPI analysis and to identify 10 Hub genes. Functional enrichment analysis provided new ways to seek potential biological functions. Besides, we established a prognostic signature of PCa patients based on 8 prognostic-associated mRNAs. We confirmed that the survival rates of PCa patients with high-risk subgroup were slightly lower than those with low-risk subgroup in the TCGA dataset (p<0.001), and ROC curves revealed that the AUC value for prognostic signature was 0.816. Finally, the functional analysis suggested that knockdown of hsa_circ_0047641 could inhibit the progression of PCa and could reverse Enz-resistance in vitro.

Conclusion

We identified 13 EnzR-related circRNAs, and constructed and confirmed that EnzR-related circRNA-miRNA-mRNA ceRNA network and corresponding prognostic signature could be a useful prognostic biomarker and therapeutic target.

The diverse roles of circular RNAs in pancreatic cancer

Pancreatic cancer is one of the malignant tumors with poor prognosis. The molecular mechanisms of pancreatic oncogenesis and malignant progression are not fully elucidated. Several key signaling pathways, such as Notch, Wnt and hedgehog pathways, are important to drive pancreatic carcinogenesis. Recently, noncoding RNAs, especially circular RNAs (circRNAs), have been characterized to participate into pancreatic cancer development. Therefore, in this review article, we describe the association between circRNAs and pancreatic cancer prognosis. Moreover, we discuss how circRNAs are involved in regulation of cellular processes in pancreatic cancer, including proliferation, apoptosis, cell cycle, migration, invasion, EMT, metastasis, angiogenesis, drug resistance and immune escape. Furthermore, we mention that several compounds could regulate the expression of circRNAs, indicating that targeting circRNAs by compounds might be helpful for treating pancreatic cancer patients.

Therapeutic Potential of Pharmacological Targeting NLRP3 Inflammasome Complex in Cancer

Introduction

Dysregulation of NLRP3 inflammasome complex formation can promote chronic inflammation by increased release of IL-1β. However, the effect of NLRP3 complex formation on tumor progression remains controversial. Therefore, we sought to determine the effect of NLRP3 modulation on the growth of the different types of cancer cells, derived from lung, breast, and prostate cancers as well as neuroblastoma and glioblastoma in-vitro.

Method

The effect of Caspase 1 inhibitor (VX765) and combination of LPS/Nigericin on NLRP3 inflammasome activity was analyzed in A549 (lung cancer), MCF-7 (breast cancer), PC3 (prostate cancer), SH-SY5Y (neuroblastoma), and U138MG (glioblastoma) cells. Human fibroblasts were used as control cells. The effect of VX765 and LPS/Nigericin on NLRP3 expression was analyzed using western blot, while IL-1β and IL-18 secretion was detected by ELISA. Tumor cell viability and progression were determined using Annexin V, cell proliferation assay, LDH assay, sphere formation assay, transmission electron microscopy, and a multiplex cytokine assay. Also, angiogenesis was investigated by a tube formation assay. VEGF and MMPs secretion were detected by ELISA and a multiplex assay, respectively. Statistical analysis was done using one-way ANOVA with Tukey’s analyses and Kruskal–Wallis one-way analysis of variance.

Results

LPS/Nigericin increased NRLP3 protein expression as well as IL-1β and IL-18 secretion in PC3 and U138MG cells compared to A549, MCF7, SH-SY5Y cells, and fibroblasts. In contrast, MIF expression was commonly found upregulated in A549, PC3, SH-SY5Y, and U138MG cells and fibroblasts after Nigericin treatment. Nigericin and a combination of LPS/Nigericin decreased the cell viability and proliferation. Also, LPS/Nigericin significantly increased tumorsphere size in PC3 and U138MG cells. In contrast, the sphere size was reduced in MCF7 and SH-SY5Y cells treated with LPS/Nigericin, while no effect was detected in A549 cells. VX765 increased secretion of CCL24 in A549, MCF7, PC3, and fibroblasts as well as CCL11 and CCL26 in SH-SY5Y cells. Also, VX765 significantly increased the production of VEGF and MMPs and stimulated angiogenesis in all tumor cell lines.

Discussion

Our data suggest that NLRP3 activation using Nigericin could be a novel therapeutic approach to control the growth of tumors producing a low level of IL-1β and IL-18.

Evidence of nigericin as a potential therapeutic candidate for cancers: A review

Emerging studies have shown that nigericin, an H⁺, K⁺ and Pb²⁺ ionophore, has exhibited a promising anti-cancer activity in various cancers. However, its anti-cancer mechanisms have not been fully elucidated. In this review, the recent progresses on the use of nigericin in human cancers have been summarized. By exchanging H⁺ and K⁺ across cell membranes, nigericin shows promising anti-cancer activities in in vitro and in vivo as a single agent or in combination with other anti-cancer drugs through decreasing intracellular pH (pHi). The underlying mechanisms of nigericin also include the inactivation of Wnt/β-catenin signals, blockade of Androgen Receptor (AR) signaling, and activation of Stress-Activated Protein Kinase/c-Jun N-terminal Kinase (SAPK/JNK) signaling pathways. In many cancers, nigericin is proved to specifically target putative Cancer Stem Cells (CSCs), and its synergistic effects on photodynamic therapy are also reported. Other mechanisms of nigericin including influencing the mitochondrial membrane potentials, inducing an increase in drug accumulation and autophagy, controlling insulin accumulation in nuclei, and increasing the cytotoxic activity of liposome-entrapped drugs, are also discussed. Notably, the potential adverse effects such as teratogenic effects, insulin resistance and eryptosis shall not be ignored. Taken together, these reports suggest that treatment of cancer cells with nigericin may offer a novel therapeutic strategy and future potential of translation to clinics.

Circular RNA profiling identifies circ102049 as a key regulator of colorectal liver metastasis

Circular RNA (circRNA) plays an essential role in the development and progression of various cancers. However, the functions and mechanisms of circRNA in colorectal liver metastasis have not been fully elucidated. We performed circRNA microarray analysis to screen differentially expressed circRNA in the pathology of colorectal liver metastasis. Quantitative real-time PCR was used to detect the expression of hsa_circ_102049 (circ102049) in colorectal cancer (CRC) samples. CRC cells were transfected with circ102049 overexpression vector or small interfering (si)RNA to assess the effects of circ102049 in vitro. Bioinformatics analysis, fluorescence in situ hybridization, RNA immunoprecipitation, RNA pull-down and luciferase reporter assays were conducted to confirm the relationship of circ102049, miR-761, miR-192-3p and FRAS1. The mechanism by which circ102049 recruits and distributes DGCR8 protein in the cytoplasm was also investigated. We found that circ102049 was highly expressed in primary CRC tumors with liver metastasis and closely correlated with the prognosis of patients with CRC. Circ102049 significantly enhanced the adhesion, migration and invasion abilities of CRC cells, and promoted CRC progression via a micro (mi)R-761/miR-192-3p-FRAS1-dependent mechanism. Notably, due to the distribution of DGCR8 protein, circ102049 may also indirectly reduce the levels of mature miR-761 and miR-192-3p in the cytoplasm. In addition, the role of circ102049 in promoting colorectal liver metastasis was confirmed in vivo. Our findings provide new evidence that circ102049 may be a potential prognostic factor in CRC, and that the circ102049-miR-761/miR-192-3p-FRAS1 axis may be an anti-metastatic target for CRC patients.

Molecular Screening for Nigericin Treatment in Pancreatic Cancer by High-Throughput RNA Sequencing

Objectives: Nigericin, an antibiotic derived from Streptomyces hygroscopicus, has been proved to exhibit promising anti-cancer effects on a variety of cancers. Our previous study investigated the potential anti-cancer properties in pancreatic cancer (PC), and demonstrated that nigericin could inhibit the cell viabilities in concentration- and time-dependent manners via differentially expressed circular RNAs (circRNAs). However, the knowledge of nigericin associated with long non-coding RNA (lncRNA) and mRNA in pancreatic cancer (PC) has not been studied. This study is to elucidate the underlying mechanism from the perspective of lncRNA and mRNA.

Methods: The continuously varying molecules (lncRNAs and mRNAs) were comprehensively screened by high-throughput RNA sequencing.

Results: Our data showed that 76 lncRNAs and 172 mRNAs were common differentially expressed in the nigericin anti-cancer process. Subsequently, the bioinformatics analyses, including Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, coding and non-coding co-expression network, cis- and trans-regulation predictions and protein-protein interaction (PPI) network, were applied to annotate the potential regulatory mechanisms among these coding and non-coding RNAs during the nigericin anti-cancer process.

Conclusions: These findings provided new insight into the molecular mechanism of nigericin toward cancer cells, and suggested a possible clinical application in PC.

CircHIPK3 Promotes Gemcitabine (GEM) Resistance in Pancreatic Cancer Cells by Sponging miR-330-5p and Targets RASSF1

Background

Pancreatic cancer is one of the most common malignant diseases in the world. Gemcitabine chemotherapy remains the most important clinical treatment. However, research found that pancreatic cancer cells have chemoresistance to gemcitabine and the effect is not satisfactory. Therefore, it is urgent to find an effective early diagnosis and treatment strategy. Circular RNA is one of the most popular prognostic biomarkers in GEM-resistant PC.

Materials and Methods

The present study was designed to evaluate the role of circHIPK3 in PC. The expression of circHIPK3 in PC tissues and cells and its effect on proliferation, migration, invasion, EMT, and apoptosis were investigated in vitro; its effect on tumor xenografts was assessed in vivo. Used bioinformation analysis to predict which miRNAs could potentially interact with circHIPK3, mRNA, and miR-330-5p.

Results

RT-PCR showed that the level of circHIPK3 was increased in PC tumor tissues; moreover, circHIPK3 was also increased in GEM-resistant PC tumors tissues and GEM-resistant PC cells. Sh-circHIPK3 could knockdown circHIPK3 in PANC-1-GEM and SW-1990-GEM and could significantly inhibit cell proliferation, invasion, migration, EMT and enhance cell apoptosis, compare with control group, the tumor xenografts of circHIPK3 knockdown group were significantly smaller. CircHIPK3 served as a sponge for miR-330-5p, and miR-330-5p directly bound to the 3′ UTR of RASSF1 were revealed by dual luciferase assay and RIP in PC cells. CircHIPK3 knockdown of RASSF1 expression could neutralize the cytological function of PC cells by miR-330-5p inhibitor mediated GEM-resistance.

Conclusion

CircHIPK3 promotes gemcitabine (GEM) resistance in pancreatic cancer cells by targeting RASSF1 via miR-330-5p and regulates proliferation, invasive, migration, EMT, and apoptosis. Our research revealed that circHIPK3 may be a novel biomarker in GEM-resistant PC and could be used as a prognostic target.