Alternative RNA Splicing Defects in Pediatric Cancers: New Insights in Tumorigenesis and Potential Therapeutic Vulnerabilities

Pan-cancer oncogenic properties and therapeutic potential of SF3B4

Splicing factor 3B (SF3B) subunit 4 (SF3B4), an SF3B complex component essential for spliceosome assembly and accurate splicing, plays a major role in cancer development. However, the precise mechanism through which SF3B4 contributes to tumor growth remains unclear. Here, we demonstrate that SF3B4 is strongly expressed in patients with various cancer types and correlated with their survival. By using hepatocellular carcinoma (HCC) as a model, we reveal that SF3B4's interactions with and regulatory influence on the checkpoint protein BUB1 are essential for appropriate cancer cell mitosis and proliferation. Our results thus demonstrate the roles of SF3B4 as both a cell-cycle regulator and an oncogenic factor in HCC, highlighting its potential as a pan-cancer therapeutic target and diagnostic biomarker.

Advances in neoantigen-based immunotherapy for head and neck squamous cell carcinoma: a comprehensive review

Head and Neck Squamous Cell Carcinoma (HNSCC), ranking among the six most prevalent malignancies worldwide, is characterized by significant heterogeneity. Conventional monotherapeutic approaches, including surgical intervention, radiotherapy, and chemotherapy, often fail to achieve complete tumor cell elimination, consequently leading to disease recurrence and metastatic progression. In this context, personalized immunotherapeutic strategies, particularly cancer vaccines and immune checkpoint inhibitors, have emerged as promising therapeutic modalities for patients with recurrent/metastatic (R/M) HNSCC. Neoantigens, which exhibit selective expression in tumor tissues while remaining absent in normal tissues, have garnered considerable attention as novel targets for HNSCC personalized immunotherapy. However, the marked heterogeneity of HNSCC, coupled with patient-specific HLA variations, necessitates precise technical identification and evaluation of neoantigens at the individual level-a significant contemporary challenge. This comprehensive review systematically explores the landscape of neoantigen-based immunotherapy in HNSCC, including neoantigen sources, screening strategies, identification methods, and their clinical applications. Additionally, it evaluates the therapeutic potential of combining neoantigen-based approaches with other immunotherapeutic modalities, particularly immune checkpoint inhibitors, providing valuable insights for future clinical practice and research directions in HNSCC treatment.

KPNA2 promotes osteosarcoma progression by regulating the alternative splicing of DDX3X mediated by YBX1

Osteosarcoma (OS) is a rapidly progressive primary malignant bone tumor that occurs in children and adolescents aged between 15 and 19 years and adults aged over 60 years. As alternative splicing (AS) changes caused by abnormal splicing factors contribute to tumor progression, gene expression and AS analyses were performed on 44 osteosarcoma patients to create a genome-wide co-expression network of RNA-binding proteins (RBPs), AS events, and AS genes. A gain- or loss-of-function osteosarcoma cell model was established, and an interactive network analysis and enrichment analysis were performed. Karyopherin Subunit Alpha 2 (KPNA2) negatively correlated with patient survival. KPNA2 transports splicing factor Y-box Binding Protein 1 (YBX1) into the nucleus and YBX1 accelerates the degradation of the ATP-dependent RNA helicase DDX3X (DDX3X) through the nonsense-mediated decay (NMD) pathway to promote intron retention of the DDX3X gene, thus reducing DDX3X protein levels. KPNA2/YBX1 axis regulates the stability of DDX3X mRNA and cell cycle progression. KPNA2/YBX1/DDX3X axis might be potential targets for inhibiting disease progression and improving OS patient survival. It integrates AS control of DDX3X into the progression of OS and represents a potential prognostic biomarker and therapeutic target for OS therapy.

Global, regional, and national burden of neuroblastoma and peripheral nervous system tumours in individuals aged over 60 from 1990 to 2021: a trend analysis of global burden of disease study

PURPOSE

Elderly individuals diagnosed with neuroblastoma and peripheral nervous system tumours often have a poor prognosis. However, there is currently a lack of comprehensive analysis on these conditions in older adults. This study aims to determine the global epidemiological trends of neuroblastoma and peripheral nervous system tumours (in individuals aged 60 and above).

METHODS

We obtained cross-sectional data from the 2021 Global Burden of Disease, Injuries, and Risk Factors Study (GBD) ( https://vizhub.healthdata.org/gbd-results/ ). We assessed the burden of neuroblastoma and peripheral nervous system tumours in the elderly from 1990 to 2021 using indicators such as prevalence and incidence. These indicators were classified by global, national, and regional levels, further stratified by Socio-Demographic Index (SDI), age, and gender. The results are organized by SDI, age, and gender categories.

RESULTS

From 1990 to 2021, the global age-standardised prevalence and incidence rates of neuroblastoma and peripheral nervous system tumours among the elderly increased from 0.06 (95% UI 0.05, 0.08) and 0.12 (95% UI 0.09, 0.15) per 100,000 to 0.11 (95% UI 0.09, 0.13) and 0.22 (95% UI 0.17, 0.26) per 100,000, respectively. Age-standardised mortality and DALY rates also rose. Central Europe had the highest age-standardised prevalence and incidence rates in 2021, while Eastern Europe had the highest DALY rate. East Asia reported the highest number of total cases and experienced the fastest growth, with significant increases in prevalence, incidence, mortality, and DALY rates. Gender disparities were evident, with elderly men showing higher rates than women, and greater EAPC values indicating a higher increase in disease burden over time. The highest age-specific rates were found in the 90-94 age group, while the 70-74 age group had the highest DALY burden.

CONCLUSION

The continuous rise in the incidence of neuroblastoma and peripheral nervous system tumours among the elderly highlights a pressing the necessity for focused public health measures and improved treatment approaches. Addressing the regional, gender, and age-related disparities requires a comprehensive approach that integrates medical advancements, social support, and public health policies. Future research should explore potential risk factors and innovative therapies to mitigate this growing global health challenge.

Characterization of a pleomorphic rhabdomyosarcoma cell line

Pleomorphic rhabdomyosarcoma (PRMS) is an extremely rare soft tissue tumor with dismal prognosis that has a higher incidence in adults compared to the other RMS subtypes. The unique PRMS cell line BH1522 was established from a pleural effusion of a lung metastasis and the characteristics of this cell line were compared to two embryonal type RMS (ERMS) cell lines. The affected patient had been treated by surgery, several cycles of chemotherapy and thoracoscopy of the lung metastases. Chemosensitivity of the PRMS cell lines was checked using cytotoxicity assays and oncogene-related and phosphoproteins by Western blot arrays. The BH1522 cell line proved to be chemosensitive to conventional chemotherapeutics and the Son of Sevenless 1 homolog (SOS1) inhibitor BAY-293 that inhibited proliferation and suppressed MYC activity. Results of the novel functional BH1522 tests corroborate published tumor sequencing data that demonstrated alterations in receptor tyrosine kinase/MAPK, PI3K/AKT and mutated p53 as suspected drivers of malignant growth.

Genome-wide analysis of alternative splicing differences in hepatic ischemia reperfusion injury

Alternative splicing (AS) contributes to transcript and protein diversity, affecting their structure and function. However, the specific transcriptional regulatory mechanisms underlying AS in the context of hepatic ischemia reperfusion (IR) injury in mice have not been extensively characterized. In this study, we investigated differentially alternatively spliced (DAS) genes and differentially expressed transcripts (DETs) in a mouse model of hepatic IR injury using the high throughput RNA sequencing (RNA-seq) analysis and replicate multivariate analysis of transcript splicing (rMATS) analysis. We further conducted Gene ontology (GO) term enrichment, the Kyoto Encyclopedia of Genes and Genomes (KEGG) database and the protein-protein interaction (PPI) network. A total of 898 DAS genes (p ≤ 0.05) were screened out in the hepatic IR group compared to the sham group, while functional enrichment analysis revealed that DETs and DAS genes were significantly associated with the ATP-dependent chromain, splicesome and metabolic pathways. The expression level of the DAS genes: Gabpb2, Smg1, Tnrc6c, Mettl17, Smpd4, Kcnt2, D16Ertd472e, Rab3gap2, Echdc2 and Ssx2ip were verified by RT-PCR and qRT-PCR. Our findings provide a comprehensive genome-wide view of AS events in hepatic IR injury in mice, enhancing our understanding of AS dynamics and the molecular mechanisms governing alternative pre-mRNA splicing.

SNRNP70 regulates the splicing of CD55 to promote osteosarcoma progression

Osteosarcoma (OS) is the most common malignant bone tumor, characterized by a high propensity for metastasis. Recent studies have highlighted the role of alternative splicing in cancer metastasis, although the precise mechanisms underlying aberrant splicing in OS invasion and metastasis remain unclear. Here, we analyzed consistently differentially expressed genes and differentially alternative splicing events between primary and metastatic OS to identify potential genes associated with OS progression. U1 small nuclear ribonucleoprotein 70K (SNRNP70) emerged as both differentially expressed and spliced, with elevated SNRNP70 levels correlating with poor prognosis in pateints with OS. Functional experiments demonstrated that SNRNP70 overexpression enhanced the proliferation and metastasis of OS cells in vitro, while its depletion reduced these capabilities in vivo. Mechanistically, SNRNP70 directly interacted with CD55, modulating its alternative splicing and promoting tumor progression in OS. Additionally, metastatic OS samples exhibited increased infiltration of resting immune cells, and single-cell RNA sequencing revealed communication between SNRNP70-expressing osteoblastic cells and macrophages via the ADGRE5/CD55 signaling pathway. Overall, our results showed that SNRNP70 knockdown inhibited OS progression, which was associated with the splicing of CD55, indicating SNRNP70 as a promising target for OS treatment.

Microproteins encoded by short open reading frames: Vital regulators in neurological diseases

Short open reading frames (sORFs) are frequently overlooked because of their historical classification as non-coding elements or dismissed as "transcriptional noise". However, advanced genomic and proteomic technologies have allowed for screening and validating sORFs-encoded peptides, revealing their fundamental regulatory roles in cellular processes and sparking a growing interest in microprotein biology. In neuroscience, microproteins serve as neurotransmitters in signal transmission and regulate metabolism and emotions, exerting pivotal effects on neurological conditions such as nerve injury, neurogenic tumors, inflammation, and neurodegenerative diseases. This review summarizes the origins, characteristics, classifications, and functions of microproteins, focusing on their molecular mechanisms in neurological disorders. Potential applications, future perspectives, and challenges are discussed.

The neoantigens derived from transposable elements - A hidden treasure for cancer immunotherapy

Neoantigen-based therapy is a promising approach that selectively activates the immune system of the host to recognize and eradicate cancer cells. Preliminary clinical trials have validated the feasibility, safety, and immunogenicity of personalized neoantigen-directed vaccines, enhancing their effectiveness and broad applicability in immunotherapy. While many ongoing oncological trials concentrate on neoantigens derived from mutations, these targets do not consistently provoke an immune response in all patients harboring the mutations. Additionally, tumors like ovarian cancer, which have a low tumor mutational burden (TMB), may be less amenable to mutation-based neoantigen therapies. Recent advancements in next-generation sequencing and bioinformatics have uncovered a rich source of neoantigens from non-canonical RNAs associated with transposable elements (TEs). Considering the substantial presence of TEs in the human genome and the proven immunogenicity of TE-derived neoantigens in various tumor types, this review investigates the latest findings on TE-derived neoantigens, examining their clinical implications, challenges, and unique advantages in enhancing tumor immunotherapy.

DNA damage response and neoantigens: A favorable target for triple-negative breast cancer immunotherapy and vaccine development

Triple-negative breast cancer (TNBC) poses a significant clinical challenge due to its aggressive nature and limited therapeutic options. The interplay between DNA damage response (DDR) mechanisms and the emergence of neoantigens represents a promising avenue for developing targeted immunotherapeutic strategies and vaccines for TNBC. The DDR is a complex network of cellular mechanisms designed to maintain genomic integrity. In TNBC, where genetic instability is a hallmark, dysregulation of DDR components plays a pivotal role in tumorigenesis and progression. This review explores the intricate relationship between DDR and neoantigens, shedding light on the potential vulnerabilities of TNBC cells. Neoantigens, arising from somatic mutations in cancer cells, represent unique antigens that can be recognized by the immune system. TNBC's propensity for genomic instability leads to an increased mutational burden, consequently yielding a rich repertoire of neoantigens. The convergence of DDR and neoantigens in TNBC offers a distinctive opportunity for immunotherapeutic targeting. Immunotherapy has revolutionized cancer treatment by harnessing the immune system to selectively target cancer cells. The unique immunogenicity conferred by DDR-related neoantigens in TNBC positions them as ideal targets for immunotherapeutic interventions. This review also explores various immunotherapeutic modalities, including immune checkpoint inhibitors (ICIs), adoptive cell therapies, and cancer vaccines, that leverage the DDR and neoantigen interplay to enhance anti-tumor immune responses. Moreover, the potential for developing vaccines targeting DDR-related neoantigens opens new frontiers in preventive and therapeutic strategies for TNBC. The rational design of vaccines tailored to the individual mutational landscape of TNBC holds promise for precision medicine approaches. In conclusion, the convergence of DDR and neoantigens in TNBC presents a compelling rationale for the development of innovative immunotherapies and vaccines. Understanding and targeting these interconnected processes may pave the way for personalized and effective interventions, offering new hope for patients grappling with the challenges posed by TNBCs.

Role of alternative splicing in fish immunity

Alternative splicing serves as a pivotal source of complexity in the transcriptome and proteome, selectively connecting various coding elements to generate a diverse array of mRNAs. This process encodes multiple proteins with either similar or distinct functions, contributing significantly to the intricacies of cellular processes. The role of alternative splicing in mammalian immunity has been well studied. Remarkably, the immune system of fish shares substantial similarities with that of humans, and alternative splicing also emerges as a key player in the immune processes of fish. In this review, we offer an overview of alternative splicing and its associated functions in the immune processes of fish, and summarize the research progress on alternative splicing in the fish immunity. Furthermore, we review the impact of alternative splicing on the fish immune system's response to external stimuli. Finally, we present our perspectives on future directions in this field. Our aim is to provide valuable insights for the future investigations into the role of alternative splicing in immunity.

Modification of BCLX pre-mRNA splicing has antitumor efficacy alone or in combination with radiotherapy in human glioblastoma cells

Dysregulation of anti-apoptotic and pro-apoptotic protein isoforms arising from aberrant splicing is a crucial hallmark of cancers and may contribute to therapeutic resistance. Thus, targeting RNA splicing to redirect isoform expression of apoptosis-related genes could lead to promising anti-cancer phenotypes. Glioblastoma (GBM) is the most common type of malignant brain tumor in adults. In this study, through RT-PCR and Western Blot analysis, we found that BCLX pre-mRNA is aberrantly spliced in GBM cells with a favored splicing of anti-apoptotic Bcl-xL. Modulation of BCLX pre-mRNA splicing using splice-switching oligonucleotides (SSOs) efficiently elevated the pro-apoptotic isoform Bcl-xS at the expense of the anti-apoptotic Bcl-xL. Induction of Bcl-xS by SSOs activated apoptosis and autophagy in GBM cells. In addition, we found that ionizing radiation could also modulate the alternative splicing of BCLX. In contrast to heavy (carbon) ion irradiation, low energy X-ray radiation-induced an increased ratio of Bcl-xL/Bcl-xS. Inhibiting Bcl-xL through splicing regulation can significantly enhance the radiation sensitivity of 2D and 3D GBM cells. These results suggested that manipulation of BCLX pre-mRNA alternative splicing by splice-switching oligonucleotides is a novel approach to inhibit glioblastoma tumorigenesis alone or in combination with radiotherapy.

OutSplice: A Novel Tool for the Identification of Tumor-Specific Alternative Splicing Events

Protein variation that occurs during alternative splicing has been shown to play a major role in disease onset and oncogenesis. Due to this, we have developed OutSplice, a user-friendly algorithm to classify splicing outliers in tumor samples compared to a distribution of normal samples. Several tools have previously been developed to help uncover splicing events, each coming with varying methodologies, complexities, and features that can make it difficult for a new researcher to use or to determine which tool they should be using. Therefore, we benchmarked several algorithms to determine which may be best for a particular user's needs and demonstrate how OutSplice differs from these methodologies. We find that despite detecting a lower number of genes with significant aberrant events, OutSplice is able to identify those that are biologically impactful. Additionally, we identify 17 genes that contain significant splicing alterations in tumor tissue that were discovered across at least 5 of the tested algorithms, making them good candidates for future studies. Overall, researchers should consider a combined use of OutSplice with other splicing software to help provide additional validation for aberrant splicing events and to narrow down biologically relevant events.

Genetics in ophthalmology: molecular blueprints of retinoblastoma

This review presents current knowledge on the molecular biology of retinoblastoma (RB). Retinoblastoma is an intraocular tumor with hereditary and sporadic forms. 8,000 new cases of this ocular malignancy of the developing retina are diagnosed each year worldwide. The major gene responsible for retinoblastoma is RB1, and it harbors a large spectrum of pathogenic variants. Tumorigenesis begins with mutations that cause RB1 biallelic inactivation preventing the production of functional pRB proteins. Depending on the type of mutation the penetrance of RB is different. However, in small percent of tumors additional genes may be required, such as MYCN, BCOR and CREBBP. Additionally, epigenetic changes contribute to the progression of retinoblastoma as well. Besides its role in the cell cycle, pRB plays many additional roles, it regulates the nucleosome structure, participates in apoptosis, DNA replication, cellular senescence, differentiation, DNA repair and angiogenesis. Notably, pRB has an important role as a modulator of chromatin remodeling. In recent years high-throughput techniques are becoming essential for credible biomarker identification and patient management improvement. In spite of remarkable advances in retinoblastoma therapy, primarily in high-income countries, our understanding of retinoblastoma and its specific genetics still needs further clarification in order to predict the course of this disease and improve therapy. One such approach is the tumor free DNA that can be obtained from the anterior segment of the eye and be useful in diagnostics and prognostics.

Eukaryotic splicing machinery in the plant-virus battleground

Plant virual infections are mainly caused by plant-virus parasitism which affects ecological communities. Some viruses are highly pathogen specific that can infect only specific plants, while some can cause widespread harm, such as tobacco mosaic virus (TMV) and cucumber mosaic virus (CMV). After a virus infects the host, undergoes a series of harmful effects, including the destruction of host cell membrane receptors, changes in cell membrane components, cell fusion, and the production of neoantigens on the cell surface. Therefore, competition between the host and the virus arises. The virus starts gaining control of critical cellular functions of the host cells and ultimately affects the fate of the targeted host plants. Among these critical cellular processes, alternative splicing (AS) is an essential posttranscriptional regulation process in RNA maturation, which amplify host protein diversity and manipulates transcript abundance in response to plant pathogens. AS is widespread in nearly all human genes and critical in regulating animal-virus interactions. In particular, an animal virus can hijack the host splicing machinery to re-organize its compartments for propagation. Changes in AS are known to cause human disease, and various AS events have been reported to regulate tissue specificity, development, tumour proliferation, and multi-functionality. However, the mechanisms underlying plant-virus interactions are poorly understood. Here, we summarize the current understanding of how viruses interact with their plant hosts compared with humans, analyze currently used and putative candidate agrochemicals to treat plant-viral infections, and finally discussed the potential research hotspots in the future. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.

Targeting alternative splicing in cancer immunotherapy

Tumor immunotherapy has made great progress in cancer treatment but still faces several challenges, such as a limited number of targetable antigens and varying responses among patients. Alternative splicing (AS) is an essential process for the maturation of nearly all mammalian mRNAs. Recent studies show that AS contributes to expanding cancer-specific antigens and modulating immunogenicity, making it a promising solution to the above challenges. The organoid technology preserves the individual immune microenvironment and reduces the time/economic costs of the experiment model, facilitating the development of splicing-based immunotherapy. Here, we summarize three critical roles of AS in immunotherapy: resources for generating neoantigens, targets for immune-therapeutic modulation, and biomarkers to guide immunotherapy options. Subsequently, we highlight the benefits of adopting organoids to develop AS-based immunotherapies. Finally, we discuss the current challenges in studying AS-based immunotherapy in terms of existing bioinformatics algorithms and biological technologies.

Diverse targets of SMN2-directed splicing-modulating small molecule therapeutics for spinal muscular atrophy

Designing an RNA-interacting molecule that displays high therapeutic efficacy while retaining specificity within a broad concentration range remains a challenging task. Risdiplam is an FDA-approved small molecule for the treatment of spinal muscular atrophy (SMA), the leading genetic cause of infant mortality. Branaplam is another small molecule which has undergone clinical trials. The therapeutic merit of both compounds is based on their ability to restore body-wide inclusion of Survival Motor Neuron 2 (SMN2) exon 7 upon oral administration. Here we compare the transcriptome-wide off-target effects of these compounds in SMA patient cells. We captured concentration-dependent compound-specific changes, including aberrant expression of genes associated with DNA replication, cell cycle, RNA metabolism, cell signaling and metabolic pathways. Both compounds triggered massive perturbations of splicing events, inducing off-target exon inclusion, exon skipping, intron retention, intron removal and alternative splice site usage. Our results of minigenes expressed in HeLa cells provide mechanistic insights into how these molecules targeted towards a single gene produce different off-target effects. We show the advantages of combined treatments with low doses of risdiplam and branaplam. Our findings are instructive for devising better dosing regimens as well as for developing the next generation of small molecule therapeutics aimed at splicing modulation.

Seven non-differentially expressed 'dark biomarkers' show transcriptional dysregulation in chronic lymphocytic leukemia

Aim: Transcriptional regulation is actively involved in the onset and progression of various diseases. This study used the feature-engineering approach model-based quantitative transcription regulation to quantitatively measure the correlation between mRNA and transcription factors in a reference dataset of chronic lymphocytic leukemia (CLL) transcriptomes. Methods: A comprehensive investigation of transcriptional regulation changes in CLL was conducted using 973 samples in six independent datasets. Results & conclusion: Seven mRNAs were detected to have significantly differential model-based quantitative transcription regulation values but no differential expression between CLL patients and controls. We called these genes 'dark biomarkers' because their original expression levels did not show differential changes in the CLL patients. The overlapping lncRNAs might have contributed their transcripts to the expression miscalculations of these dark biomarkers.

Neoantigens: promising targets for cancer therapy

Recent advances in neoantigen research have accelerated the development and regulatory approval of tumor immunotherapies, including cancer vaccines, adoptive cell therapy and antibody-based therapies, especially for solid tumors. Neoantigens are newly formed antigens generated by tumor cells as a result of various tumor-specific alterations, such as genomic mutation, dysregulated RNA splicing, disordered post-translational modification, and integrated viral open reading frames. Neoantigens are recognized as non-self and trigger an immune response that is not subject to central and peripheral tolerance. The quick identification and prediction of tumor-specific neoantigens have been made possible by the advanced development of next-generation sequencing and bioinformatic technologies. Compared to tumor-associated antigens, the highly immunogenic and tumor-specific neoantigens provide emerging targets for personalized cancer immunotherapies, and serve as prospective predictors for tumor survival prognosis and immune checkpoint blockade responses. The development of cancer therapies will be aided by understanding the mechanism underlying neoantigen-induced anti-tumor immune response and by streamlining the process of neoantigen-based immunotherapies. This review provides an overview on the identification and characterization of neoantigens and outlines the clinical applications of prospective immunotherapeutic strategies based on neoantigens. We also explore their current status, inherent challenges, and clinical translation potential.

Splicing-Disrupting Mutations in Inherited Predisposition to Solid Pediatric Cancer

The prevalence of hereditary cancer in children was estimated to be very low until recent studies suggested that at least 10% of pediatric cancer patients carry a germline mutation in a cancer predisposition gene. A significant proportion of pathogenic variants associated with an increased risk of hereditary cancer are variants affecting splicing. RNA splicing is an essential process involved in different cellular processes such as proliferation, survival, and differentiation, and alterations in this pathway have been implicated in many human cancers. Hereditary cancer genes are highly susceptible to splicing mutations, and among them there are several genes that may contribute to pediatric solid tumors when mutated in the germline. In this review, we have focused on the analysis of germline splicing-disrupting mutations found in pediatric solid tumors, as the discovery of pathogenic splice variants in pediatric cancer is a growing field for the development of personalized therapies. Therapies developed to correct aberrant splicing in cancer are also discussed as well as the options to improve the diagnostic yield based on the increase in the knowledge in splicing.

Fine-Tuning the Relevance of Molecular Targets to Pediatric Cancer: Addressing Additional Layers of Complexity

The Research to Accelerate Cures and Equity (RACE) for Children Act requires an assessment of molecular targets relevant to pediatric cancer. Due to the biological complexity, candidate molecular targets have been primarily evaluated based on single features such as the presence of mutations or deregulated expression. As the understanding of tumor biology evolves, the relevance of certain molecular targets may need to be assessed at isoform and/or mutation variant level to optimize tailored therapeutic interventions.

The emerging role of pyroptosis in pediatric cancers: from mechanism to therapy

Pediatric cancers are the driving cause of death for children and adolescents. Due to safety requirements and considerations, treatment strategies and drugs for pediatric cancers have been so far scarcely studied. It is well known that tumor cells tend to progressively evade cell death pathways, which is known as apoptosis resistance, one of the hallmarks of cancer, dominating tumor drug resistance. Recently, treatments targeting nonapoptotic cell death have drawn great attention. Pyroptosis, a newly specialized form of cell death, acts as a critical physiological regulator in inflammatory reaction, cell development, tissue homeostasis and stress response. The action in different forms of pyroptosis is of great significance in the therapy of pediatric cancers. Pyroptosis could be induced and consequently modulate tumorigenesis, progression, and metastasis if treated with local or systemic therapies. However, excessive or uncontrolled cell death might lead to tissue damage, acute inflammation, or even cytokine release syndrome, which facilitates tumor progression or recurrence. Herein, we aimed to describe the molecular mechanisms of pyroptosis, to highlight and discuss the challenges and opportunities for activating pyroptosis pathways through various oncologic therapies in multiple pediatric neoplasms, including osteosarcoma, neuroblastoma, leukemia, lymphoma, and brain tumors.

Cytogenetic and Genetic Abnormalities with Diagnostic Value in Myelodysplastic Syndromes (MDS): Focus on the Pre-Messenger RNA Splicing Process

Myelodysplastic syndromes (MDS) are considered to be diseases associated with splicing defects. A large number of genes involved in the pre-messenger RNA splicing process are mutated in MDS. Deletion of 5q and 7q are of diagnostic value, and those chromosome regions bear the numbers of splicing genes potentially deleted in del(5q) and del(7q)/-7 MDS. In this review, we present the splicing genes already known or suspected to be implicated in MDS pathogenesis. First, we focus on the splicing genes located on chromosome 5 (HNRNPA0, RBM27, RBM22, SLU7, DDX41), chromosome 7 (LUC7L2), and on the SF3B1 gene since both chromosome aberrations and the SF3B1 mutation are the only genetic abnormalities in splicing genes with clear diagnostic values. Then, we present and discuss other splicing genes that are showing a prognostic interest (SRSF2, U2AF1, ZRSR2, U2AF2, and PRPF8). Finally, we discuss the haploinsufficiency of splicing genes, especially from chromosomes 5 and 7, the important amplifier process of splicing defects, and the cumulative and synergistic effect of splicing genes defects in the MDS pathogenesis. At the time, when many authors suggest including the sequencing of some splicing genes to improve the diagnosis and the prognosis of MDS, a better understanding of these cooperative defects is needed.