Comprehensive Characterization of Circular RNAs in Neuroblastoma Cell Lines

Upregulation of circGDI2 inhibits tumorigenesis by stabilizing the expression of RNA m6A demethylase FTO in oral squamous cell carcinoma

Background

Oral squamous cell carcinoma (OSCC) is a malignant tumour that is difficult to identify and prone to metastasis and invasion. Circular RNAs (circRNAs) are important cancer regulators and can be used as potential biomarkers. However, OSCC-related circRNAs need to be further explored. We investigated the role of circGDI2 in OSCC and explored its downstream regulatory mechanisms.

Methods

Quantitative real-time PCR was used to detect the expression levels of circGDI2 and fat mass and obesity-associated protein (FTO) in cells. Lentiviral transfection was used to construct stable circGDI2 overexpressing cells for subsequent cell function tests. RNA pull-down, RNA Immunoprecipitation (RIP), western blotting, and protein stability assays were conducted to detect circGDI2 binding proteins and their functions. CCK8, Transwell, and wound healing assays were used to verify cell functions after overexpressing circGDI2 or suppressing FTO expression. Animal experiments were performed to verify the results in vivo.

Results

The expression of circGDI2 was markedly decreased in both OSCC cell lines and patient tissues. Overexpression of circGDI2 in OSCC cell lines led to decreased proliferation, migration, and invasion abilities. Knockdown of circGDI2 showed the opposite trend. CircGDI2 has been validated to interact with the FTO protein within cells, as evidenced by mass spectrometry and RIP assays. This interaction was found to prevent the degradation of the FTO protein. Dot blot analysis showed a reduction in N6-methyladenosine (m6A) modification after circGDI2 overexpression. Reduced FTO levels reversed the inhibitory effects of circGDI2 overexpression on cell proliferation, migration, and invasion in vitro and on tumorigenesis in vivo.

Conclusions

CircGDI2 functions as a tumour suppressor by binding to the FTO protein to reduce RNA m6A modification levels and ultimately inhibit proliferation and migration in OSCC cells. This study indicates the potential use of circGDI2 as a new target for the prevention and treatment of OSCC.

Circ_0001361/miR-490-5p/IGF2 Axis Regulates the Viability and Apoptosis of Neuroblastoma Cells

BACKGROUND

Circular RNAs (circRNAs) are involved in the neuroblastoma (NB) development. Objectie: The study aimed to determine the biological behaviors of circ_0001361 and explore its underlying mechanism in NB.

METHODS

The circ_0001361, miR-490-5p, and IGF2 levels were measured using quantitative real-time polymerase chain reaction. Cellular processes were analyzed using MTT assay or fluorescence-activated cell sorting (FACS). Phosphorylated (p)-PI3K, p-AKT, Bax, and caspase-3 were tested by western blot. Dual-luciferase reporter analysis together with RNA pull-down analysis were utilized to evaluate the correlation of miR-490-5p and circ_0001361 or IGF2.

RESULTS

The results in this study illustrated that an elevation of circ_0001361 levels was observed in NB. Depletion of circ_0001361 suppressed the viability but facilitated apoptosis of NB cells. Circ_0001361 sponged miR-490-5p, which targeted to regulate IGF2. Inhibition of miR-490-5p rescued the effect induced by circ_0001361 knockdown, while deletion of IGF2 rescued the effect induced by the miR-490-5p inhibitor.

CONCLUSIONS

In summary, a loss of circ_0001361 inhibited NB progression via targeting the miR-490-5p/IGF2 axis, suggesting that circ_0001361 may be a novel therapeutical target of NB.

EIF2S1 Silencing Impedes Neuroblastoma Development Through GPX4 Inactivation and Ferroptosis Induction

Background: Neuroblastoma (NB) is one of the most devastating malignancies in children, accounting for a high mortality rate due to limited treatment options. This study is aimed at elucidating the role of the ferroptosis-related EIF2S1 gene in NB pathogenesis and exploring its potential as a therapeutic target. Methods: We conducted comprehensive bioinformatics analyses utilizing the FerrDb database and NB-related transcriptomics data to investigate the role of EIF2S1 in NB. Changes in EIF2S1 expression were subsequently validated in NB tissues and cell lines. Loss-of-function experiments were performed in SK-N-SH and IMR-32 cell lines through shRNA-mediated EIF2S1 knockdown. The impact of EIF2S1 knockdown on the tumorigenesis of SK-N-SH cells was assessed in nude mice. Results: Bioinformatics analyses revealed a significant association between elevated EIF2S1 expression and poor prognosis in NB patients. The increased levels of EIF2S1 expression were confirmed in NB tissues and cancerous cell lines. Furthermore, EIF2S1 overexpression was linked to translational regulation and immune cell infiltration modulation. Silencing of EIF2S1 resulted in the suppression of cell proliferation, migration, and tumorigenicity in NB cells. Additionally, EIF2S1 knockdown led to an accumulation of iron and oxidative stress, as well as a reduction in GPX4 and SLC7A11 expression. Conclusion: Our findings indicate that EIF2S1 appears to facilitate the progression of NB by protecting tumor cells from ferroptosis through modulating GPX4 and SLC7A11 expression. Consequently, EIF2S1 may serve as a potential therapeutic target for the management of NB.

Integrative analysis of bulk RNA-seq and scRNA-seq data indicates the prognostic and immunologic values of SERPINH1 in glioma

BACKGROUND

SERPINH1 is abnormally expressed in multiple cancers and is associated with malignant progression. However, few reports detail its role in the etiopathogenesis of glioma. Hence, the aim of this article was to investigate the potential value of SERPINH1 in glioma using an integrative analysis.

METHODS

Data of RNA-seq and scRNA-seq was obtained and evaluated using online databases. The expression of SERPINH1 was confirmed by qRT-PCR and immunohistochemistry. The prognostic value of SERPINH1 was evaluated using univariate and multivariate Cox regression analyses. SERPINH1-related signaling pathways and the interaction of SERPINH1 with immunity were also investigated.

RESULTS

SERPINH1 exhibited a markedly elevated expression in glioma compared to normal brain tissues in the online databases. Similar results were confirmed by qRT-PCR and immunohistochemistry. SERPINH1 was found to be an independent prognosis factor, and high expression of SERPINH1 indicated poor survival. Moreover, a nomogram was constructed to predict prognosis more accurately and intuitively. GSEA analysis showed that SERPINH1 was involved in seven signaling pathways, including JAK-STAT pathway. Further analysis indicated SERPINH1 was significantly associated with immunity, especially in low-grade glioma. Additionally, an examination of scRNA-seq data revealed that SERPINH1 was primarily expressed in T cells of the CD4+ and CD8+ subsets.

CONCLUSIONS

SERPINH1 is a key biomarker of glioma prognosis and is immunologically relevant, which provides additional options for targeted therapy of glioma.

Epigenetic Dysregulation in MYCN-Amplified Neuroblastoma

Neuroblastoma (NB), a childhood cancer arising from the neural crest, poses significant clinical challenges, particularly in cases featuring amplification of the MYCN oncogene. Epigenetic factors play a pivotal role in normal neural crest and NB development, influencing gene expression patterns critical for tumorigenesis. This review delves into the multifaceted interplay between MYCN and known epigenetic modifications during NB genesis, shedding light on the intricate regulatory networks underlying the disease. We provide an extensive survey of known epigenetic mechanisms, encompassing DNA methylation, histone modifications, non-coding RNAs, super-enhancers (SEs), bromodomains (BET), and chromatin modifiers in MYCN-amplified (MNA) NB. These epigenetic changes collectively contribute to the dysregulated gene expression landscape observed in MNA NB. Furthermore, we review emerging therapeutic strategies targeting epigenetic regulators, including histone deacetylase inhibitors (HDACi), histone methyltransferase inhibitors (HMTi), and DNA methyltransferase inhibitors (DNMTi). We also discuss and summarize current drugs in preclinical and clinical trials, offering insights into their potential for improving outcomes for MNA NB patients.

Recent advances and application value of circRNA in neuroblastoma

Neuroblastoma (NB) is children’s most prevalent solid malignant tumor, accounting for 15% of childhood cancer mortality. Non-coding RNA is important in NB pathogenesis. As a newly identified non-coding RNA, abnormal regulation (abnormal up-regulation or down-regulation) of the circRNAs expression is implicated in the tumorigenesis of various tumors, including NB. CircRNAs primarily regulate the expression of microRNA (miRNA) target genes by microRNA (miRNA) sponge adsorption. Clinical evidence suggests that the expression of certain circRNAs is associated with the prognosis and clinical features of NB and hence may be exploited as a biomarker or therapeutic target. This review examines circRNAs that have been demonstrated to play a function in NB.

Hsa_circ_0001361 facilitates cell progression and glycolytic metabolism in neuroblastoma via interacting with mir-490-5p to induce TRIM2 upregulation

Circular RNAs (circRNAs) can regulate the progression of neuroblastoma (NB) via miRNA/mRNA axis. This study aimed to investigate the functional mechanism of hsa_circ_0001361 in NB. Hsa_circ_0001361, miR-490-5p and tripartite motif 2 (TRIM2) were detected through reverse transcription-quantitative polymerase chain reaction. The proliferation ability was examined using cell counting kit-8 assay, colony formation assay and ethynyl-2'-deoxyuridine assay. Cell migration and invasion were assessed via transwell assay and wound healing assay. The protein levels were measured by western blot. Glycolysis was analyzed via commercial kits. Dual-luciferase reporter assay and RNA immunoprecipitation assay were performed for target analysis. Hsa_circ_0001361 research in vivo was performed using xenograft tumor assay. Hsa_circ_0001361 was overexpressed in NB tissues and cells. Hsa_circ_0001361 downregulation suppressed cell proliferation, metastasis and glycolysis. Hsa_circ_0001361 served as a miR-490-5p sponge. The functions of hsa_circ_0001361 in NB cells were associated with miR-490-5p sponging effect. Hsa_circ_0001361 resulted in TRIM2 expression change via targeting miR-490-5p. MiR-490-5p acted as a tumor inhibitor in NB by downregulating TRIM2. Hsa_circ_0001361 knockdown reduced tumor growth in vivo through mediating miR-490-5p/TRIM2 axis. Our results suggested that hsa_circ_0001361 upregulated TRIM2 by absorbing miR-490-5p, thereby promoting cell malignant behaviors and glycolytic metabolism in NB.

CircFNDC3B regulates osteoarthritis and oxidative stress by targeting miR-525-5p/HO-1 axis

Osteoarthritis (OA) is a common chronic degenerative joint disease associated with a variety of risk factors including aging, genetics, obesity, and mechanical disturbance. This study aimed to elucidate the function of a newly discovered circular RNA (circRNA), circFNDC3B, in OA progression and its relationship with the NF-κB signaling pathway and oxidative stress. The circFNDC3B/miR-525-5p/HO-1 axis and its relationship with the NF-κB signaling pathway and oxidative stress were investigated and validated using fluorescence in situ hybridization, real-time PCR, western blotting, immunofluorescence analysis, luciferase reporter assays, pull-down assays, and reactive oxygen species analyses. The functions of circFNDC3B in OA was investigated in vitro and in vivo. These evaluations demonstrated that circFNDC3B promotes chondrocyte proliferation and protects the extracellular matrix (ECM) from degradation. We also revealed that circFNDC3B defends against oxidative stress in OA by regulating the circFNDC3B/miR-525-5p/HO-1 axis and the NF-κB signaling pathway. Further, we found that overexpression of circFNDC3B alleviated OA in a rabbit model. In summary, we identified a new circFNDC3B/miR-525-5p/HO-1 signaling pathway that may act to relieve OA by alleviating oxidative stress and regulating the NF-κB pathway, resulting in the protection of the ECM in human chondrocytes, highlighting it as a potential therapeutic target for the treatment of OA.

CircRANBP17 modulated KDM1A to regulate neuroblastoma progression by sponging miR-27b-3p

Neuroblastoma (NB) is a common childhood cancer. Circular RNA RAN binding protein 17 (circRANBP17) has been identified to participate in diverse tumor progression. This study aims to explore the function and mechanism of circRANBP17 in NB. The levels of circRANBP17, miR-27b-3p and KDM1A in NB tissues and cells were measured by qRT-PCR. Mouse model assay was performed to investigate the effect of circRANBP17 knockdown on tumor formation in vivo. The levels of circRANBP17 and KDM1A were significantly up-regulated, and the level of miR-27b-3p was strikingly down-regulated in NB tissues and cells (SK-N-SH and SK-N-AS). Functional studies indicated that miR-27b-3p inhibitor mitigated the inhibitory effects on cell proliferation, migration, invasion and the promoting effect on cell apoptosis in SK-N-SH and SK-N-AS cells induced by circRANBP17 knockdown. Also, miR-27b-3p regulated NB cell malignancy by targeting KDM1A. Further studies revealed that miR-27b-3p inhibitor reversed the low expression of KDM1A induced by circRANBP17 knockdown. In support, circRANBP17 knockdown led to inhibition of tumor formation in vivo. In conclusion, circRANBP17 modulated KDM1A to promote cell proliferation, migration, invasion and restrain cell apoptosis in NB by sponging miR-27b-3p, and the new regulatory network may provide a theoretical basis for the further study of NB.

An Update on Circular RNA in Pediatric Cancers

Circular RNAs (circRNAs) are a class of single-stranded closed noncoding RNA molecules which are formed as a result of reverse splicing of mRNAs. Despite their relative abundance, only recently there appeared an increased interest in the understanding of their regulatory importance. Among their most relevant characteristics are high stability, abundance and evolutionary conservation among species. CircRNAs are implicated in several cellular functions, ranging from miRNA and protein sponges to transcriptional modulation and splicing. Additionally, circRNAs' aberrant expression in pathological conditions is bringing to light their possible use as diagnostic and prognostic biomarkers. Their use as indicator molecules of pathological changes is also supported by their peculiar covalent closed cyclic structure which bestows resistance to RNases. Their regulatory role in cancer pathogenesis and metastasis is supported by studies involving human tumors that have investigated different expression profiles of these molecules. As endogenous competitive RNA, circRNAs can regulate tumor proliferation and invasion and they arouse great consideration as potential therapeutic biomarkers and targets for cancer. In this review, we describe the most recent findings on circRNAs in the most common pediatric solid cancers (such as brain tumors, neuroblastomas, and sarcomas) and in more rare ones (such as Wilms tumors, hepatoblastomas, and retinoblastomas).

Circular RNAs in neuroblastoma: Pathogenesis, potential biomarker, and therapeutic target

Neuroblastoma (NB) is a common cancer in childhood responsible for 15 % of fatalities by pediatric cancers. Epigenetic factors play an important role in the pathogenesis of NB. Recently, it has been demonstrated that circular RNAs (circRNAs, ciRNAs), a newly identified class of non-coding RNAs, are also dysregulated in NB. CircRNAs mediate their functions by regulating gene expression mainly through microRNA (miRNA) sponging. The dysregulation (abnormal upregulation or downregulation) of circRNAs is involved in tumorigenesis of a variety of tumors including NB. It seems that the expression of some circRNAs is correlated with NB prognosis and clinical features. CircRNAs might be favorable as a diagnostic/prognostic biomarker and therapeutic target. However, due to the lack of studies, it is difficult to make a conclusion regarding the clinical benefits of circRNAs. In this review, we discussed the circRNAs that experimentally have been proved to be dysregulated in NB tissues and cancer cells.

bub1 as a potential oncogene and a prognostic biomarker for neuroblastoma

Background

Neuroblastoma is the most common malignant extracranial tumor for children. Molecular mechanisms underpinning the pathogenesis of this disease are yet to be fully clarified. This study aimed to identify a novel oncogene that could be used as a biomarker informing the prognosis of neuroblastoma, and to predict its biological functions, using bioinformatics and molecular biology tools.

Methods

Three data sets from the TARGET, GSE62564, and GSE85047 databases were used for analysis. Survivals of patients with high or low expression of bub1 were compared, using the Kaplan-Meier curve and log-rank test. Immune infiltration was evaluated using ESTIMATE and MCP-counter algorithms. Synthetic small interfering RNAs (siRNAs) were employed to silence bub1 expression in neuroblastoma cell lines SH-SY5Y and SK-N-SH, in order to characterize its biological functions. Gene enrichment analyses of bub1 were carried out, using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses.

Results

Expression of bub1 was found to significantly affect overall survival and event-free survival of patients with neuroblastoma, positively correlate with the expressions of tpx2 and the ASPM gene, and negatively correlate with host immune infiltration. Expression of bub1 was elevated in patients with neuroblastoma. Silencing bub1 expression using siRNAs in SH-SY5Y and SK-N-SH resulted in decreased cell growth (p < 0.05), reduced migration (p < 0.05), and increased apoptosis (p < 0.05). Function analysis of bub1 revealed cancer-promoting effects, probably via regulating several important downstream molecules, including that related to the apoptosis process and epithelial-mesenchymal transition.

Conclusion

We identified a potential tumor-promoting gene bub1 for neuroblastoma that could also serve as a prognostic biomarker.

Silencing of Circ_0135889 Restrains Proliferation and Tumorigenicity of Human Neuroblastoma Cells

INTRODUCTION

Neuroblastoma (NB) is the most common extracranial solid tumor in infants and young children. Circular ribonucleic acid (RNA) hsa_circ_0135889 (circ_0135889; hsa_circ argonaute 2 _001) is highly expressed in multiple cancer tissues, including NB. However, its role in tumor progression of NB was unclear.

METHODS

Real-time quantitative polymerace chain reaction was used to detect RNA expression, and western blotting, or immunohistochemistry was used to measure protein expression. Functional experiments were performed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, 5-Ethynyl-2'- deoxyuridine, Annexin V-fluorescein isothiocyanate/propidium iodide, and transwell assays, as well as xenograft tumor model. The intermolecular interaction was predicted by online databases and confirmed by dual-luciferase reporter assay and RNA pull-down assay.

RESULTS

Circ_0135889 and neuronal differentiation 1 (NEUROD1) were upregulated whilst microRNA (miR)-127-5p, was downregulated in NB tumors and immortalized NB cells. Silencing of circ_0135889 could suppress cell proliferation, migration and invasion, but enhance apoptosis rate of NB cells in vitro. More importantly, circ_0135889 depletion inhibited xenograft tumor growth of NB cells. Circ_0135889 was a sponge for miR-127-5p, and inhibition of miR-127-5p counteracted the inhibitory impact of circ_0135889 knockdown on the malignant behaviors of NB cells. Moreover, NEUROD1 was a direct target of miR-127-5p, and miR-127-5p exerted the anti-tumor role in NB cells by targeting NEUROD1. Furthermore, circ_0135889 regulated NEUROD1expression by sponging miR-127-5p.

CONCLUSIONS

Circ_0135889 promoted the tumorigenicity of NB by regulating miR-127-5p/NEUROD1 axis, which might provide a promising therapeutic target for NB.

hsa_circ_0001955 Promotes Colorectal Cancer Progression by Regulating miR-583/FGF21 Axis

Objective

Hsa_circ_0001955 presents significant upregulation in colorectal cancer (CRC) tissues. However, its role in CRC remains unclear. Thus, we attempted to clarify functions of hsa_circ_0001955 on CRC.

Methods

qRT-PCR was performed to examine hsa_circ_0001955, miR-583, and FGF21 levels. Western blotting was conducted to measure FGF21 protein expression. CCK-8, flow cytometry, and Ki-67 immunohistochemical staining and TUNEL assays were conducted to assess proliferation and apoptosis in vitro and in vivo, respectively. Cell invasion and migration were assessed by Transwell assay. Tumor-bearing mouse model and HE staining were used to assess inflammatory injury. Luciferase reporter system and RNA pull-down were conducted to evaluate the regulation between miR-583 and hsa_circ_0001955 or FGF21.

Results

We found that hsa_circ_0001955 showed characteristics of upregulated circRNA in CRC. Further analysis indicated that hsa_circ_0001955 elevation facilitated CRC cell malignancy in vitro and promoted tumor growth in vivo. Furthermore, hsa_circ_0001955 was a miR-583 sponge and FGF21 was directly targeted by miR-583. In addition, we found that downregulation of miR-583 promoted hsa_circ_0001955-mediated CRC cell malignancy in vitro. In contrast, FGF21 elevation promoted miR-583-regulated CRC cell malignancy in vitro.

Conclusion

We demonstrated that hsa_circ_0001955 facilitated CRC progression via miR-583/FGF21 axis, suggesting that hsa_circ_0001955 may provide a novel insight for therapy of CRC.

CircRNA-ACAP2 contributes to the invasion, migration, and anti-apoptosis of neuroblastoma cells through targeting the miRNA-143-3p-hexokinase 2 axis

BACKGROUND

Circulating RNAs (Circ-RNAs) are tightly related to the processes of neuroblastoma. The circ-ACAP2 has been reported as dysregulated in various cancers; however, its biological roles and mechanisms in neuroblastoma remain largely unclear.

METHODS

We collected 40 neuroblastoma tissues and adjacent noncancerous tissues. Quantitative reverse transcription polymerase chain reaction (qRT-RCR) or western blot were used to examine ACAP2, miR-143-3p, and HK2 abundances. Cell migration, invasion, glycolysis, and apoptosis were assessed via wound healing, transwell, glucose uptake and lactate, 3-(4,5-diamethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and flow cytometry. The association between circRNA, microRNA (miRNA), and messenger RNA (mRNA) was examined by dual-luciferase reporter analysis and RNA immunoprecipitation.

RESULTS

The abundances of ACAP2 and HK2 were remarkedly increased in neuroblastoma tissues and cell lines. Silencing ACAP2 significantly constrained neuroblastoma cell migration, invasion, and glycolysis, and promoted apoptosis. Bioinformatics prediction, luciferase assay, and RNA pull-down assay consistently demonstrated that ACAP2 sponged miR-143-3p to downregulate its expression in neuroblastoma cells. Furthermore, we identified that hexokinase 2, a glycolysis key enzyme, was a direct target of miR-143-3p in neuroblastoma cells. Rescue of miR-143-3p in ACAP2-overexpressing cells effectively mitigated the influence of ACAP2 on neuroblastoma cell processes.

CONCLUSIONS

Our study revealed biological roles and molecular mechanisms for circ-ACAP2 in the oncogenic characteristics of neuroblastoma, facilitating the development of circRNA-based treatment approaches for anti-brain tumor therapy.

Crosstalk between circRNAs and the PI3K/AKT signaling pathway in cancer progression

Circular RNAs (circRNAs), covalently closed noncoding RNAs, are widely expressed in eukaryotes and viruses. They can function by regulating target gene expression, linear RNA transcription and protein generation. The phosphoinositide 3-kinase (PI3K)/AKT signaling pathway plays key roles in many biological and cellular processes, such as cell proliferation, growth, invasion, migration, and angiogenesis. It also plays a pivotal role in cancer progression. Emerging data suggest that the circRNA/PI3K/AKT axis modulates the expression of cancer-associated genes and thus regulates tumor progression. Aberrant regulation of the expression of circRNAs in the circRNA/PI3K/AKT axis is significantly associated with clinicopathological characteristics and plays an important role in the regulation of biological functions. In this review, we summarized the expression and biological functions of PI3K-AKT-related circRNAs in vitro and in vivo and assessed their associations with clinicopathological characteristics. We also further discussed the important role of circRNAs in the diagnosis, prognostication, and treatment of cancers.

In Vitro Assessment of the Role of p53 on Chemotherapy Treatments in Neuroblastoma Cell Lines

Neuroblastoma is the most frequent malignant extracranial solid tumor of infancy. The overall objective of this work consists of determining the presence of alterations in the p53/MDM2/p14ARF signaling pathway in neuroblastoma cell lines and deciphering their possible relationship with resistance to known antineoplastic drugs and to differentiation agents. Firstly, we characterized 10 neuroblastoma cell lines for alterations at the p53/MDM2/p14ARF signaling pathway by analysis of TP53 point mutations, MYCN and MDM2 amplification, and p14ARF methylation, homozygous deletions, and expression. Secondly, we chose SK-N-FI (mutated at TP53) and SK-N-Be(2) (wild-type TP53) cell lines, treated them with chemotherapeutic agents (doxorubicin, etoposide, cisplatin, and melphalan) and with two isomers of retinoic acid (RA): (9-cis and all-trans). Finally, we analyzed the distribution of the cell cycle, the induction of apoptosis, and the expression levels of p53, p21, and Bcl-2 in those two cell lines. P14ARF did not present promoter methylation, homozygous deletions, and protein expression in any of the 10 neuroblastoma cell lines. One TP53 point mutation was detected in the SK-N-FI cell line. MYCN amplification was frequent, while most cell lines did not present MDM2 amplification. Treatment of SK-N-FI and SK-N-Be(2) cells with doxorubicin, etoposide, cisplatin, and melphalan increased apoptosis and blocked the cycle in G2/M, while retinoic acid isomers induced apoptosis and decreased the percentage of cells in S phase in TP53 mutated SK-N-FI cells, but not in TP53 wild-type SK-N-Be(2) cells. Treatment with cisplatin, melphalan, or 9-cis RA decreased p53 expression levels in SK-N-FI cells but not in SK-N-Be (2). The expression of p21 was not modified in either of the two cell lines. Bcl-2 levels were reduced only in SK-N-FI cells after treatment with cisplatin. However, treatments with doxorubicin, etoposide, or 9-cis-RA did not modify the levels of this protein in either of the two cell lines. In conclusion, TP53 mutated SK-N-FI cells respond better to the retinoic isomers than TP53 wild-type SK-N-Be(2) cells. Although these are in vitro results, it seems that deciphering the molecular alterations of the p53/MDM2/p14ARF signaling pathway prior to treating patients of neuroblastoma might be useful for standardizing therapies with the aim of improving survival.

A Critical Role of Peptidylprolyl Isomerase A Pseudogene 22/microRNA-197-3p/Peptidylprolyl Isomerase A Axis in Hepatocellular Carcinoma

The burden of hepatocellular carcinoma (HCC) worldwide is increasing over time, while the underlying molecular mechanism of HCC development is still under exploration. Pseudogenes are classified as a special type of long non-coding RNAs (lncRNAs), and they played a vital role in regulating tumor-associated gene expression. Here, we report that a pseudogene peptidylprolyl isomerase A pseudogene 22 (PPIAP22) and its parental gene peptidylprolyl isomerase A (PPIA) were upregulated in HCC and were associated with the clinical outcomes of HCC. Further investigation revealed that PPIAP22 might upregulate the expression of PPIA through sponging microRNA (miR)-197-3p, behaving as competing endogenous RNA (ceRNA). PPIA could participate in the development of HCC by regulating mRNA metabolic process and tumor immunity based on the functional enrichment analysis. We also found a strong correlation between the expression levels of PPIA and the immune cell infiltration or the expression of chemokines, especially macrophage, C-C motif chemokine ligand 15 (CCL15), and C-X-C motif chemokine ligand 12 (CXCL12). Our findings demonstrate that the PPIAP22/miR-197-3p/PPIA axis plays a vital role in the progression of HCC by increasing the malignancy of tumor cells and regulating the immune cell infiltration, especially macrophage, through CCL15-CCR1 or CXCL12-CXCR4/CXCR7 pathways.