Progress in the studies on the molecular mechanisms associated with multidrug resistance in cancers

Chemotherapy is one of the important methods to treat cancer, and the emergence of multidrug resistance (MDR) is one major cause for the failure of cancer chemotherapy. Almost all anti-tumor drugs develop drug resistance over a period of time of application in cancer patients, reducing their effects on killing cancer cells. Chemoresistance can lead to a rapid recurrence of cancers and ultimately patient death. MDR may be induced by multiple mechanisms, which are associated with a complex process of multiple genes, factors, pathways, and multiple steps, and today the MDR-associated mechanisms are largely unknown. In this paper, from the aspects of protein-protein interactions, alternative splicing (AS) in pre-mRNA, non-coding RNA (ncRNA) mediation, genome mutations, variance in cell functions, and influence from the tumor microenvironment, we summarize the molecular mechanisms associated with MDR in cancers. In the end, prospects for the exploration of antitumor drugs that can reverse MDR are briefly discussed from the angle of drug systems with improved targeting properties, biocompatibility, availability, and other advantages.

The pattern of alternative splicing and DNA methylation alteration and their interaction in linseed (Linum usitatissimum L) response to repeated drought stresses

BACKGROUND: Drought stress has significantly hampered agricultural productivity worldwide and can also result in modifications to DNA methylation levels. However, the dynamics of DNA methylation and its association with the changes in gene transcription and alternative splicing (AS) under drought stress are unknown in linseed, which is frequently cultivated in arid and semiarid regions. RESULTS: We analysed AS events and DNA methylation patterns in drought-tolerant (Z141) and drought-sensitive (NY-17) linseed under drought stress (DS) and repeated drought stress (RD) treatments. We found that the number of intron-retention (IR) and alternative 3' splice site (Alt3'SS) events were significantly higher in Z141 and NY-17 under drought stress. We found that the linseed response to the DS treatment was mainly regulated by transcription, while the response to the RD treatment was coregulated by transcription and AS. Whole genome-wide DNA methylation analysis revealed that drought stress caused an increase in the overall methylation level of linseed. Although we did not observe any correlation between differentially methylated genes (DMGs) and differentially spliced genes (DSGs) in this study, we found that the DSGs whose gene body region was hypermethylated in Z141 and hypomethylated in NY-17 were enriched in abiotic stress response Gene Ontology (GO) terms. This finding implies that gene body methylation plays an important role in AS regulation in some specific genes. CONCLUSION: Our study is the first comprehensive genome-wide analysis of the relationship between linseed methylation changes and AS under drought and repeated drought stress. Our study revealed different interaction patterns between differentially expressed genes (DEGs) and DSGs under DS and RD treatments and differences between methylation and AS regulation in drought-tolerant and drought-sensitive linseed varieties. The findings will probably be of interest in the future. Our results provide interesting insights into the association between gene expression, AS, and DNA methylation in linseed under drought stress. Differences in these associations may account for the differences in linseed drought tolerance.

Study on RHD and RHCE gene mRNA based on three generation sequencing technology / 中国输血杂志

【Objective】 To establish RH gene mRNA sequencing method based on nanopores sequencing and to explore the RHD and RHCE mRNA transcripts in D positive and Del individuals. 【Methods】 From March 2021 to May 2022, 5 RhD positive samples and 5 Del samples screened out by hospitals in Chengdu were sent to our laboratory for futher examination. The erythrocytes and buff coat were isolated, then DNA and RNA were extracted.All 10 samples were genotyped by PCR-SSP. After the mRNA was reversely transcribed into cDNA, the full-length mRNA of RHD and RHCE genes were simultaneously amplified by a pair of primers. Sanger sequencing and third-generation sequencing technology based on Nanopore were used to sequence the amplified products, and the types and expressions of different splices of RHD and RHCE gene mRNA transcripts were analyzed. 【Results】 The method established in this study can simultaneously amplify the full length transcripts of RHD and RHCE. Ten different RHD gene mRNA transcripts and nine RHCE gene mRNA transcripts were detected in 10 samples. RHD full-length transcript (RHD-201) can be detected in RhD Del type, but the expression amount was significantly lower than that in RhD positive samples. The expression amount of transcript RHD-207 (Del789) in Del samples was significantly higher than that in RhD positive samples. The transcript RHD-208 (Del8910+ 213) was only detected in RhD Del type individuals, and no significant difference was found between other RHD transcripts and all RHCE transcripts in the two phenotypes. 【Conclusion】 In this study, an analytical method for sequencing full-length transcript isomers of RHD and RHCE mRNA via the third generation was successfully established, and complex alternative splicing patterns were found in RHD and RHCE genes, providing a new method for the study of alternative splicing of blood group gene variants mRNA.

An overview of disease treatment strategies targeting the alternative splicing of pre-mRNA / 药学学报

Alternative splicing of pre-messenger RNA (pre-mRNA) is a crucial mechanism for the diversity of the human transcriptome and proteome. Alternative splicing is a complex gene regulation process. Whole-transcriptome analysis shows that 95% of human exonic genes are alternatively spliced, involving various cis-acting elements and trans-acting factors. Any changes in any component or step may cause erroneous splicing events and lead to the occurrence of various related diseases. In addition to gene replacement therapy that directly changes the splicing results, RNA splicing modification is expected to become a new therapeutic strategy to alleviate or treat diseases by targeting and correcting abnormal pre-mRNA splicing. Splicing modification tools currently developed including RNA trans-splicing, antisense oligonucleotides, small interfering RNA, and small molecule drugs can correct abnormal splicing through different ways. This article reviews the resent progress of epigenetic regulation of pre-mRNA alternative splicing in recent years, and discusses the occurrence and regulation of alternative splicing, the types of diseases caused by related splicing defects, and the current-used tools for targeting and altering splicing. The importance of splicing modification strategies in the future treatment of human diseases is envisioned.

Alternative splicing events in tumors and targeted therapy / 药学学报

Alternative splicing is the key to human gene expression regulation and plays a decisive role in enlarging the diversity of functional proteins. Alternative splicing is an important biomarker in tumor progression, which is closely related to the development of tumors. Tumor cells tend to produce alternative spliceosome that are conducive to their progression. Therefore, targeting regulation of tumor-specific alternative spliceosomes is a potential strategy for tumor therapy. Herein, we provide a brief review of the complex relationship between alternative splicing and tumors. Alternative splicing works by removing non-coding sequences of pre-mRNA and assembling protein-coding fragments in different combinations, ultimately producing proteins with different or even opposite functions. Alternative splicing events can promote the transformation of tumor cells through apoptosis, invasion, metastasis, angiogenesis, and metabolism; they can also influence the effectiveness of cancer immunotherapy by affecting genes that play a key role in the immune pathway. We proposed that direct or indirect targeting of alternative splicing factors and oligonucleotide-based therapies are the main strategies to reverse tumor alternative splicing events. These findings will help us to better understand tumor-related alternative splicing and to develop new strategies for tumor treatment.

The establishment of a prognostic model of thyroid cancer based on alternative splicing events and the study of its regulatory network / 中华检验医学杂志

Objective:To analyze the alternative splicing (AS) events of patients with thyroid carcinoma (THYC) and explore the correlation between AS events and the prognosis of THYC.Methods:The clinical data and the Percent Splice In (PSI) value of AS events of THYC were downloaded from The Cancer Gene Atlas (TCGA) database and the TCGA SpliceSeq database respectively. The occurrence of seven kinds of AS events including AA, AD, AF, AP, ME, ES and RI in THYC was investigated and the matrix of AS events and survival data was constructed. Univariate Cox regression analysis was used to screen AS events related to prognosis of THYC. To avoid over-fitting, the least absolute shrinkage and selection operator (LASSO) regression analysis was performed. Then Multivariate Cox regression analysis was used to construct prognosis model. Kaplan-Meier curve and receiver operating characteristic (ROC) curve were performed to evaluate the prognosis ability of the risk model. We also used Pearson correlation analysis to select splicing factors (SF) which were correlated with survival associated AS events. Above SF genes were enrolled to gene ontology (GO) enrichment and KEGG pathway analysis.Results:A total of 10 447 genes and 45 150 AS events in 507 THYC patients were found in the present study. Among them, ES was the main type (38.84%) and ME was the type with the least frequency (0.51%). Totally 1 842 AS events associated with prognosis of THYC patients were identified. Three AS events including USHBP1-48249-AA、CACNB1-40626-AT and BEX5-89679-AP were selected to construct the prognosis model. The risk score of 0.807 was indicated as the best cut-off value of prognosis model. The patients were divided into high-risk group (240 cases) and low-risk group (241 cases) based on the risk score. The results demonstrated that the risk model could be used as a valuable prognostic factor for THYC ( P<0.001, AUC=0.929). The SF-AS network was constructed and several SF genes, including CDK12, RBM25, DDX39B, SRRM2 and DDX46 were identified as hub genes. Conclusions:The risk model based on 3-AS events was valuable prognosis predictor of THYC. The SF-AS network provided new insight for the exploration of tumorigenesis and development of THYC.

Construction of an adenovirus vector expressing engineered splicing factor for regulating alternative splicing of YAP1 in neonatal rat cardiomyocytes / 南方医科大学学报

OBJECTIVE@#To construct an adenovirus vector expressing artificial splicing factor capable of regulating alternative splicing of Yap1 in cardiomyocytes.@*METHODS@#The splicing factors with different sequences were constructed against Exon6 of YAP1 based on the sequence specificity of Pumilio1. The PCR fragment of the artificially synthesized PUF-SR or wild-type PUFSR was cloned into pAd-Track plasmid, and the recombinant plasmids were transformed into E. coli DH5α for plasmid amplification. The amplified plasmids were digested with Pac I and transfected into 293A cells for packaging to obtain the adenovirus vectors. Cultured neonatal rat cardiomyocytes were transfected with the adenoviral vectors, and alternative splicing of YAP1 was detected using quantitative and semi-quantitative PCR; Western blotting was performed to detect the signal of the fusion protein Flag.@*RESULTS@#The transfection efficiency of the adenovirus vectors was close to 100% in rat cardiomyocytes, and no fluorescent protein was detected in the cells with plasmid transfection. The results of Western blotting showed that both the negative control and Flag-SR-NLS-PUF targeting the YAPExon6XULIE sequence were capable of detecting the expression of the protein fused to Flag. The results of reverse transcription-PCR and PCR demonstrated that the artificial splicing factor constructed based on the 4th target sequence of YAP1 effectively regulated the splicing of YAP1 Exon6 in the cardiomyocytes (P < 0.05).@*CONCLUSION@#We successfully constructed adenovirus vectors capable of regulating YAP1 alternative splicing rat cardiomyocytes.

Triple-negative breast cancer cells respond to T cells severely at the alternative splicing layer

BACKGROUND: Cross talk of tumor­immune cells at the gene expression level has been an area of intense research. However, it is largely unknown at the alternative splicing level which has been found to play important roles in the tumor­immune microenvironment. RESULTS: Here, we re-exploited one transcriptomic dataset to gain insight into tumor­immune interactions from the point of AS level. Our results showed that the AS profiles of triple-negative breast cancer cells co-cultured with activated T cells were significantly changed but not Estrogen receptor positive cells. We further suggested that the alteration in AS profiles in triple-negative breast cancer cells was largely caused by activated T cells rather than paracrine factors from activated T cells. Biological pathway analyses showed that translation initiation and tRNA aminoacylation pathways were most disturbed with T cell treatment. We also established an approach largely based on the AS factor­AS events associations and identified LSM7, an alternative splicing factor, may be responsible for the major altered events. CONCLUSIONS: Our study reveals the notable differences of response to T cells among breast cancer types which may facilitate the development or improvement of tumor immunotherapy.

Mechanisms of alternative splicing in regulating plant flowering: a review / 生物工程学报

Flowering is a critical transitional stage during plant growth and development, and is closely related to seed production and crop yield. The flowering transition is regulated by complex genetic networks, whereas many flowering-related genes generate multiple transcripts through alternative splicing to regulate flowering time. This paper summarizes the molecular mechanisms of alternative splicing in regulating plant flowering from several perspectives, future research directions are also envisioned.

Regulation effect of lipopolysaccharide on the alternative splicing and function of sweet taste receptor T1R2 / 华西口腔医学杂志

OBJECTIVES@#To identify the alternative splicing isoform of mouse sweet taste receptor T1R2, and investigate the effect of lipopolysaccharide (LPS) local injection on T1R2 alternative splicing and the function of sweet taste receptor as one of the bacterial virulence factors.@*METHODS@#After mouse taste bud tissue isolation was conducted, RNA extraction and reverse transcription polymerase chain reaction (PCR) were performed to identify the splicing isoform of T1R2. Heterologous expression experiments @*RESULTS@#T1R2 splicing isoform T1R2_Δe3p formed sweet taste receptors with T1R3, which could not be activated by sweet taste stimuli and significantly downregulated the function of canonical T1R2/T1R3. Local LPS injection significantly increased the expression ratio of T1R2_Δe3p in mouse taste buds.@*CONCLUSIONS@#LPS stimulation affects the alternative splicing of mouse sweet taste receptor T1R2 and significantly upregulates the expression of non-functional isoform T1R2_Δe3p, suggesting that T1R2 alternative splicing regulation may be one of the mechanisms by which microbial infection affects host taste perception.

Characterization of progression-related alternative splicing events in testicular germ cell tumors / 亚洲男科学杂志(英文版)

Accumulating evidence supports the significance of aberrant alternative splicing (AS) events in cancer; however, genome-wide profiling of progression-free survival (PFS)-related AS events in testicular germ cell tumors (TGCT) has not been reported. Here, we analyzed high-throughput RNA-sequencing data and percent-spliced-in values for 150 patients with TGCT. Using univariate and multivariate Cox regression analysis and a least absolute shrinkage and selection operator method, we identified the top 15 AS events most closely associated with disease progression. A risk-associated AS score (ASS) for the 15 AS events was calculated for each patient. ASS, pathological stage, and T stage were significantly associated with disease progression by univariate analysis, but only ASS and pathological stage remained significant by multivariate analysis. The ability of these variables to predict 5-year progression was assessed using receiver operating characteristic curve analysis. ASS had stronger predictive value than a combination of age, pathological stage, and T stage (area under the curve = 0.899 and 0.715, respectively). Furthermore, Kaplan-Meier analysis of patients with low and high ASS demonstrated that high ASS was associated with significantly worse PFS than low ASS (P = 1.46 × 10

Hypoxia-induced changes in intragenic DNA methylation correlate with alternative splicing in breast cancer

The tumor microenvironment is marked by gradients in the level of oxygen and nutrients, with oxygen levelsreaching a minimum at the core of the tumor, a condition known as tumor hypoxia. Mediated by members of theHIF family of transcription factors, hypoxia leads to a more aggressive tumor phenotype by transactivation ofseveral genes as well as reprogramming of pre-mRNA splicing. Intragenic DNA methylation, which is known toaffect alternative splicing in cancer, could be one of several reasons behind the changes in splicing patterns underhypoxia. Here, we have tried to establish a correlation between intragenic DNA methylation and alternative usageof exons in tumor hypoxia. First, we have generated a custom hypoxia signature consisting of 34 genes that are upregulated under hypoxia and are direct targets of HIF-1a. Using this gene expression signature, we have successfully stratified publicly available breast cancer patient samples into hypoxia positive and hypoxia negativegroups followed by mining of differentially spliced isoforms between these groups. The Hypoxia Hallmarksignature from MSigDB was also used independently to stratify the same tumor samples into hypoxic andnormoxic. We found that 821 genes were showing differential splicing between samples stratified using a customsignature, whereas, 911 genes were showing differential splicing between samples stratified using the MSigDBsignature. Finally, we performed multiple correlation tests between the methylation levels (b) of microarrayprobes located within 1 kilo base pairs of isoform-specific exons using those exons’ expression levels in the samepatient samples in which the methylation level was recorded. We found that the expression level of one of theexons of DHX32 and BICD2 significantly correlated with the methylation levels, and we were also able to predictpatient survival (p-value: 0.02 for DHX32 and 0.0024 for BICD2). Our findings provide new insights into thepotential functional role of intragenic DNA methylation in modulating alternative splicing during hypoxia.

Roles of PTBP1 in alternative splicing, glycolysis, and oncogensis / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Polypyrimidine tract-binding protein 1 (PTBP1) plays an essential role in splicing and is expressed in almost all cell types in humans, unlike the other proteins of the PTBP family. PTBP1 mediates several cellular processes in certain types of cells, including the growth and differentiation of neuronal cells and activation of immune cells. Its function is regulated by various molecules, including microRNAs (miRNAs), long non-coding RNAs (IncRNAs), and RNA-binding proteins. PTBP1 plays roles in various diseases, particularly in some cancers, including colorectal cancer, renal cell cancer, breast cancer, and glioma. In cancers, it acts mainly as a regulator of glycolysis, apoptosis, proliferation, tumorigenesis, invasion, and migration. The role of PTBP1 in cancer has become a popular research topic in recent years, and this research has contributed greatly to the formulation of a useful therapeutic strategy for cancer. In this review, we summarize recent findings related to PTBP1 and discuss how it regulates the development of cancer cells.

Anotação e caracterização de novos transcritos expressos no adenocarcinoma de pâncreas: RNAS não-codificadores longos associados a fenótipos tumorais e clínicos e formas alternativas de splicing associados a fenótipos tumorais e clínicos / Determination of relevant transcripts in ductal adenocarcinoma of pancreas: the transcriptional landscape of the long non-coding RNAs and protein-encoding RNAs revealed by the total RNAseq analysis of pancreatic adenocarcinoma

O câncer de pâncreas (PC) é uma das doenças mais devastadoras com o pior resultado de sobrevivência quando comparada com outros tipos de câncer. É apontado como o décimo câncer mais comum e a quarta causamortis por câncer, projetando-se para ser a segunda até 2030 nos Estados Unidos e na Alemanha. O PC constitui um conjunto heterogêneo de tumores, o adenocarcinoma ductal (PDAC) constitui o tipo mais frequente da neoplasia (80%). A prevenção, detecção precoce e tratamento enfrentam sérios problemas e é urgente a identificação de novos marcadores para diagnóstico, prognóstico e estratégias terapêuticas da doença. O objetivo desse trabalho foi realizar uma análise com alta-resolução do transcriptoma do PDAC) para identificar novos RNAs não codificadores, variantes de splicing e alterações transcricionais associados à malignidade. A metodologia empregada constituiu-se de gerar bibliotecas de RNA total a partir de 14 amostras cirúrgicas pareadas de tecido tumoral (PDAC) e tecido não-tumoral adjacente para sequenciamento NGS. A partir dos dados de RNAseq foi realizada a montagem do transcriptoma utilizando-se a referência do catálogo GENCODE para classificar os transcritos. Seguiram-se análises subsequentes de avaliação de características dos transcritos: estruturais, marcas regulatórias, potencial codificador, detecção em banco de dados independente (miTrascriptome, miT). Em segundo lugar foram realizadas análises de expressão diferencial, análise de sobrevida (utilizando banco de dados públicos) para seleção de transcritos potencialmente relevantes no PDAC. Foram geradas redes de co-expressão gênicas com enriquecimento de funções biológicas. Uma série de validações foram realizadas por RT-PCR de transcritos novos intergênicos e novas formas de splicing reconstruídas e selecionadas. RT-qPCR foi utilizada para validação da expressão aberrante de lncRNAs em PDAC, silenciamentos por siRNA e subsequentes ensaios de proliferação, migração e invasão. Foi avaliada in vivo o envolvimento com crescimento tumoral por ensaio xenográfico, e avaliação da implicação em funções biológicas mais específicas, como envolvimento em reparo de DNA por ensaio cometa alcalino e avaliação de enriquecimento em tumoresferas. A montagem reconstruiu 90.522 transcritos, dos quais 41.341 são anotados no GENCODE e 6.710 transcritos são novos não anotados no GENCODE (classificado como splicingvariant, intergenic RNA, antisense RNA). Desses foram validados 6 novos lincRNAs com expressão aumentada em PDAC, dois deles (TCONS00085964 e TCONS00036574) tem a expressão correlacionada com alterações na sobrevida. Foram validadas também novas formas de splicing de MMP14, CAPN8, LIF e OCT3 com expressão aumentada em PDAC. 7 lncRNAs, anotados no GENCODE, com expressão aumentada em PDAC, desses foram implicados com fenótipo tumoral de migração, invasão e proliferação: LINC01559; LINC01133, CCAT1 e UCA1. Desses LINC01559 e CCAT1 demonstraram regular a expressão de enzimas de O-glicosilação (GALNT3 e B3GNT3) envolvidas na manutenção de células tronco-tumorais em PDAC. O lncRNA UCA1 está envolvido com reparo de DNA e envolvido com a progressão tumoral invivo. Conclui-se que a abordagem por amostras pareadas a partir de RNAseq de bibliotecas de RNA total gerou um catálogo de transcritos mais completo no PDCA e revelou IncRNAs funcionalmente implicadas na doença como LINC01559 e UCA1, ampliando o conhecimento sobre os mecanismos moleculares que sustentam fenótipos malignos no câncer de pâncreas e revelando novos biomarcadores para prognóstico

Tese de DoutoradoDOIhttps://doi.org/10.11606/T.46.2019.tde-09032020-085211DocumentoTese de DoutoradoAutorPaixão, Vinicius Ferreira da (Catálogo USP)Nome completoVinicius Ferreira da PaixãoE-mailE-mailUnidade da USPInstituto de QuímicaÁrea do ConhecimentoBioquímicaData de Defesa2019-12-04ImprentaSão Paulo, 2019OrientadorReis, Eduardo Moraes (Catálogo USP) Banca examinadoraReis, Eduardo Moraes (Presidente) Hajj, Glaucia Noeli Maroso Malnic, Bettina Panepucci, Rodrigo Alexandre Título em portuguêsAnotação e caracterização de novos transcritos expressos no adenocarcinoma de pâncreas: RNAS não-codificadores longos associados a fenótipos tumorais e clínicos e formas alternativas de splicingPalavras-chave em portuguêsAlternative splicing lncRNA PDAC Transcriptoma UCA1 Xenotumor Resumo em portuguêsO câncer de pâncreas (PC) é uma das doenças mais devastadoras com o pior resultado de sobrevivência quando comparada com outros tipos de câncer. É apontado como o décimo câncer mais comum e a quarta causamortis por câncer, projetando-se para ser a segunda até 2030 nos Estados Unidos e na Alemanha. O PC constitui um conjunto heterogêneo de tumores, o adenocarcinoma ductal (PDAC) constitui o tipo mais frequente da neoplasia (80%). A prevenção, detecção precoce e tratamento enfrentam sérios problemas e é urgente a identificação de novos marcadores para diagnóstico, prognóstico e estratégias terapêuticas da doença. O objetivo desse trabalho foi realizar uma análise com alta-resolução do transcriptoma do PDAC) para identificar novos RNAs não codificadores, variantes de splicing e alterações transcricionais associados à malignidade. A metodologia empregada constituiu-se de gerar bibliotecas de RNA total a partir de 14 amostras cirúrgicas pareadas de tecido tumoral (PDAC) e tecido não-tumoral adjacente para sequenciamento NGS. A partir dos dados de RNAseq foi realizada a montagem do transcriptoma utilizando-se a referência do catálogo GENCODE para classificar os transcritos. Seguiram-se análises subsequentes de avaliação de características dos transcritos: estruturais, marcas regulatórias, potencial codificador, detecção em banco de dados independente (miTrascriptome, miT). Em segundo lugar foram realizadas análises de expressão diferencial, análise de sobrevida (utilizando banco de dados públicos) para seleção de transcritos potencialmente relevantes no PDAC. Foram geradas redes de co-expressão gênicas com enriquecimento de funções biológicas. Uma série de validações foram realizadas por RT-PCR de transcritos novos intergênicos e novas formas de splicing reconstruídas e selecionadas. RT-qPCR foi utilizada para validação da expressão aberrante de lncRNAs em PDAC, silenciamentos por siRNA e subsequentes ensaios de proliferação, migração e invasão. Foi avaliada in vivo o envolvimento com crescimento tumoral por ensaio xenográfico, e avaliação da implicação em funções biológicas mais específicas, como envolvimento em reparo de DNA por ensaio cometa alcalino e avaliação de enriquecimento em tumoresferas. A montagem reconstruiu 90.522 transcritos, dos quais 41.341 são anotados no GENCODE e 6.710 transcritos são novos não anotados no GENCODE (classificado como splicingvariant, intergenic RNA, antisense RNA). Desses foram validados 6 novos lincRNAs com expressão aumentada em PDAC, dois deles (TCONS00085964 e TCONS00036574) tem a expressão correlacionada com alterações na sobrevida. Foram validadas também novas formas de splicing de MMP14, CAPN8, LIF e OCT3 com expressão aumentada em PDAC. 7 lncRNAs, anotados no GENCODE, com expressão aumentada em PDAC, desses foram implicados com fenótipo tumoral de migração, invasão e proliferação: LINC01559; LINC01133, CCAT1 e UCA1. Desses LINC01559 e CCAT1 demonstraram regular a expressão de enzimas de O-glicosilação (GALNT3 e B3GNT3) envolvidas na manutenção de células tronco-tumorais em PDAC. O lncRNA UCA1 está envolvido com reparo de DNA e envolvido com a progressão tumoral invivo. Conclui-se que a abordagem por amostras pareadas a partir de RNAseq de bibliotecas de RNA total gerou um catálogo de transcritos mais completo no PDCA e revelou IncRNAs funcionalmente implicadas na doença como LINC01559 e UCA1, ampliando o conhecimento sobre os mecanismos moleculares que sustentam fenótipos malignos no câncer de pâncreas e revelando novos biomarcadores para prognóstico.Título em inglêsDetermination of relevant transcripts in ductal adenocarcinoma of pancreas: the transcriptional landscape of the long non-coding RNAs and protein-encoding RNAs revealed by the total RNAseq analysis of pancreatic adenocarcinomaPalavras-chave em inglêsAlternative splicing lncRNA PDAC Transcriptome UCA1 Xenotumor Resumo em inglêsPancreatic cancer (PC) is the deadliest malignancy, one of the most devastating diseases with the worst survival outcome compared to any cancer. It is touted as the tenth most common cancer and the fourth leading cause of cancer in the United States and Germany. It is projected to be the second leading cause of cancer death in a decade. PC is a heterogeneous set of tumors with high aggressiveness and mortality. Of these tumors, ductal adenocarcinoma (PDAC) is the most frequent type of cancer (80%). Prevention, early detection and treatment face serious problems, and the identification of new markers for diagnosis, prognosis and therapeutic strategies of the disease is urgent. The aim of this study was to perform a high-resolution analysis of pancreatic adenocarcinoma (PDAC) transcriptome to identify new noncoding RNAs, splicing variants, and transcriptional changes associated with malignancy in pancreatic ductal adenocarcinoma. The methodology employed consisted of generating total RNA libraries from 14 paired surgical samples of tumor tissue (PDAC) and adjacent non-tumor tissue for NGS sequencing. From the RNAseq data, the transcriptome assembly was performed using the GENCODE catalog reference to classify the transcripts. Subsequent analyzes of evaluation of transcript characteristics were followed: structural, regulatory markers, potential encoder, independent database detection (miTrascriptome, miT). Secondly, differential expression analysis, survival analysis (using public database) were performed to select potentially relevant transcripts in the PDAC. Genic co-expression networks with biological function enrichment were generated. A series of validations were performed by RT-PCR of new intergenic transcripts and new forms of reconstructed and selected splicing. RT-qPCR was used for validation of aberrant expression of lncRNAs in PDAC, siRNA silencing and subsequent proliferation, migration and invasion assays. Involvement with tumor growth was evaluated by in vivo xenograph assay. Biological function tests to determine an involvement in DNA repair was evaluated by alkaline comet assay and was performed an evaluation of tumorsphere expression enrichment. The assembly reconstructed a total of 90,522 transcripts, of which 41,341 are noted in GENCODE. 6,710 transcripts are new (splicing variant, intergenic RNA, antisense RNA) not noted in the GENCODE reference. Of these 6 new PDAC-enhanced lincRNAs were validated, two of them (TCONS00085964 and TCONS00036574) correlated with changes in survival. New forms of splicing of MMP14, CAPN8, LIF and OCT3 with increased expression in PDAC were also validated. 7 lncRNAs noted with increased expression in PDAC were implicated with tumor migration, invasion and proliferation phenotype: LINC01559; LINC01133, LINC01614; CCAT1; LINC02577; LINC00920 and UCA1. Of these LINC01559 has been shown to regulate the expression of O-glycosylation enzymes (GALNT3 and B3GNT3) involved in maintaining CSCs in PDAC. It has been identified that UCA1 is involved with DNA repair and involved with tumor progression in vivo. It is concluded that the approach of sampling RNAseq from total RNA libraries generated a more accurate transcript catalog of PDAC and revealed IncRNAs functionally implicated in the disease, such as LINC01559 and UCA1, expanding the knowledge about the molecular mechanisms that underlie malignant phenotypes in pancreatic cancer and revealing novel prognostic biomarke

mTOR-coordinated Post-Transcriptional Gene Regulations: from Fundamental to Pathogenic Insights

Post-transcriptional regulations of mRNA transcripts such as alternative splicing and alternative polyadenylation can affect the expression of genes without changing the transcript levels. Recent studies have demonstrated that these post-transcriptional events can have significant physiological impacts on various biological systems and play important roles in the pathogenesis of a number of diseases, including cancers. Nevertheless, how cellular signaling pathways control these post-transcriptional processes in cells are not very well explored in the field yet. The mammalian target of rapamycin complex 1 (mTORC1) pathway plays a key role in sensing cellular nutrient and energy status and regulating the proliferation and growth of cells by controlling various anabolic and catabolic processes. Dysregulation of mTORC1 pathway can tip the metabolic balance of cells and is associated with a number of pathological conditions, including various types of cancers, diabetes, and cardiovascular diseases. Numerous reports have shown that mTORC1 controls its downstream pathways through translational and/or transcriptional regulation of the expression of key downstream effectors. And, recent studies have also shown that mTORC1 can control downstream pathways via post-transcriptional regulations. In this review, we will discuss the roles of post-transcriptional processes in gene expression regulations and how mTORC1-mediated post-transcriptional regulations contribute to cellular physiological changes. We highlight post-transcriptional regulation as an additional layer of gene expression control by mTORC1 to steer cellular biology. These emphasize the importance of studying post-transcriptional events in transcriptome datasets for gaining a fuller understanding of gene expression regulations in the biological systems of interest.

Identification of neoantigens derived from alternative splicing and RNA modification

The acquisition of somatic mutations is the most common event in cancer. Neoantigens expressed from genes with mutations acquired during carcinogenesis can be tumor-specific. Since the immune system recognizes tumor-specific peptides, they are potential targets for personalized neoantigen-based immunotherapy. However, the discovery of druggable neoantigens remains challenging, suggesting that a deeper understanding of the mechanism of neoantigen generation and better strategies to identify them will be required to realize the promise of neoantigen-based immunotherapy. Alternative splicing and RNA editing events are emerging mechanisms leading to neoantigen production. In this review, we outline recent work involving the large-scale screening of neoantigens produced by alternative splicing and RNA editing. We also describe strategies to predict and validate neoantigens from RNA sequencing data.

Overexpressed long noncoding RNA CRNDE with distinct alternatively spliced isoforms in multiple cancers / 医学前沿

Alternative splicing is a tightly regulated process that contributes to cancer development. CRNDE is a long noncoding RNA with alternative splicing and is implicated in the pathogenesis of several cancers. However, whether deregulated expression of CRNDE is common and which isoforms are mainly involved in cancers remain unclear. In this study, we report that CRNDE is aberrantly expressed in the majority of solid and hematopoietic malignancies. The investigation of CRNDE expression in normal samples revealed that CRNDE was expressed in a tissue- and cell-specific manner. Further comparison of CRNDE expression in 2938 patient samples from 15 solid and hematopoietic tumors showed that CRNDE was significantly overexpressed in 11 malignancies, including 3 reported and 8 unreported, and also implicated that the overexpressed isoforms differed in various cancer types. Furthermore, anti-cancer drugs could efficiently repress CRNDE overexpression in cancer cell lines and primary samples, and even had different impacts on the expression of CRNDE isoforms. Finally, experimental profiles of 12 alternatively spliced isoforms demonstrated that the spliced variant CRNDE-g was the most highly expressed isoform in multiple cancer types. Collectively, our results emphasize the cancer-associated feature of CRNDE and its spliced isoforms, and may provide promising targets for cancer diagnosis and therapy.

Significance of alternative splicing in drug resistance of chronic myeloid leukemia / 中国肿瘤临床

Alternative splicing (AS) is a process by which the transcriptome diversity, and thereby the proteome diversity, is augment-ed by splicing or joining together different parts of the pre-mRNA in eukaryotic cells . AS at different splice sites is regulated by multi-ple cis-acting elements and trans-acting factors. Chronic myeloid leukemia (CML) is a clonal myeloproliferative disease in which there is a translocation between the long arms of chromosome 9 and chromosome 22, represented as t(9;22) (q34;q11). This translocation results in the formation of a BCR-ABL fusion gene. Hence it is not surprising that resistance to tyrosine kinase inhibitors, which inhibit BCR-ABL activity, has become a critical problem in the clinical treatment of CML. Using second generation high-throughput sequencing technology, it has been found that AS abnormalities are closely related to the occurrence, progression, drug resistance, and immune escape of CML. This paper reviews the research related to AS and CML resistance and investigates the potential causes of CML resis-tance. Drug resistance mechanisms and potential therapeutic targets are also reviewed.

RNA binding protein 24 deletion disrupts global alternative splicing and causes dilated cardiomyopathy

RNA splicing contributes to a broad spectrum of post-transcriptional gene regulation during normal development, as well as pathological manifestation of heart diseases. However, the functional role and regulation of splicing in heart failure remain poorly understood. RNA binding protein (RBP), a major component of the splicing machinery, is a critical factor in this process. RNA binding motif protein 24 (RBM24) is a tissue-specific RBP which is highly expressed in human and mouse heart. Previous studies demonstrated the functional role of RBM24 in the embryonic heart development. However, the role of RBM24 in postnatal heart development and heart disease has not been investigated. In this paper, using conditional RBM24 knockout mice, we demonstrated that ablation of RBM24 in postnatal heart led to rapidly progressive dilated cardiomyopathy (DCM), heart failure, and postnatal lethality. Global splicing profiling revealed that RBM24 regulated a network of genes related to cardiac function and diseases. Knockout of RBM24 resulted in misregulation of these splicing transitions which contributed to the subsequent development of cardiomyopathy. Notably, our analysis identified RBM24 as a splice factor that determined the splicing switch of a subset of genes in the sacomeric Z-disc complex, including Titin, the major disease gene of DCM and heart failure. Together, this study identifies regulation of RNA splicing by RBM24 as a potent player in remodeling of heart during postnatal development, and provides novel mechanistic insights to the pathogenesis of DCM.

Alternative splicing originates different domain structure organization of Lutzomyia longipalpis chitinases

BACKGROUND The insect chitinase gene family is composed by more than 10 paralogs, which can codify proteins with different domain structures. In Lutzomyia longipalpis, the main vector of visceral leishmaniasis in Brazil, a chitinase cDNA from adult female insects was previously characterized. The predicted protein contains one catalytic domain and one chitin-binding domain (CBD). The expression of this gene coincided with the end of blood digestion indicating a putative role in peritrophic matrix degradation. OBJECTIVES To determine the occurrence of alternative splicing in chitinases of L. longipalpis. METHODS We sequenced the LlChit1 gene from a genomic clone and the three spliced forms obtained by reverse transcription polymerase chain reaction (RT-PCR) using larvae cDNA. FINDINGS We showed that LlChit1 from L. longipalpis immature forms undergoes alternative splicing. The spliced form corresponding to the adult cDNA was named LlChit1A and the two larvae specific transcripts were named LlChit1B and LlChit1C. The B and C forms possess stop codons interrupting the translation of the CBD. The A form is present in adult females post blood meal, L4 larvae and pre-pupae, while the other two forms are present only in L4 larvae and disappear just before pupation. Two bands of the expected size were identified by Western blot only in L4 larvae. MAIN CONCLUSIONS We show for the first time alternative splicing generating chitinases with different domain structures increasing our understanding on the finely regulated digestion physiology and shedding light on a potential target for controlling L. longipalpis larval development.