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Head and neck squamous cell carcinoma (HNSCC) is the most frequent subtype of head and neck cancer, generally with a poor prognosis and limited therapeutic options due to its highly heterogeneous malignancy. In this study, we screened functional splicing regulatory RNA binding proteins (RBPs) that were closely related with the prognosis of HNSCC patients and showed significant expression differences between HNSCC tumors and normal tissues. Based on this finding, we chose six candidate genes (HNRNPC, ZCRB1, RBM12B, SF3A2, SF3B3, and SRSF11) to generate a prognostic prediction model and validated the accuracy of the prognostic model for predicting patient survival outcomes. We found that the risk score predicted by our model can serve as an independent prognostic predictor. Notably, HNSCC tumors showing higher expression of SF3B3, HNRNPC, or ZCRB1 possessed higher risk scores in the discovered prediction model. The investigation of the underlying mechanism validated that knockdown of SF3B3, HNRNPC, and ZCRB1 separately induced a substantial impairment of HNSCC cell survival. Conversely, overexpression of each of the three genes promoted tumor cellular proliferation. High throughput RNA sequencing analysis revealed that changes in the expression of SF3B3 and HNRNPC remarkably affected alternative splicing of genes related to cell cycle regulation, whereas the depletion of ZCRB1 contributed to aberrant splicing events involving in DNA damage response. In addition, the prognostic prediction model's risk score was demonstrated to be related with the immune infiltration score. Particularly, SF3B3 has a negative correlation with CD8A expression. Therefore, our findings provide promising prognosis predictors and potential therapeutic targets for better treatment efficacy of HNSCC.
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Neoplasias de Cabeça e Pescoço , Oncogenes , Humanos , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , Fatores de Processamento de RNA/genética , Processamento Alternativo , Neoplasias de Cabeça e Pescoço/genéticaRESUMO
Type I interferons exhibit anti-proliferative and anti-cancer activities, but their detailed regulatory mechanisms in cancer have not been fully elucidated yet. RNA binding proteins are master orchestrators of gene regulation, which are closely related to tumor progression. Here we show that the upregulated RNA binding protein RBM45 correlates with poor prognosis in breast cancer. Depletion of RBM45 suppresses breast cancer progression both in cultured cells and xenograft mouse models. Mechanistically, RBM45 ablation inhibits breast cancer progression through regulating type I interferon signaling, particularly by elevating IFN-ß production. Importantly, RBM45 recruits TRIM28 to IRF7 and stimulates its SUMOylation, thereby repressing IFNB1 transcription. Loss of RBM45 reduced the SUMOylation of IRF7 by reducing the interaction between TRIM28 and IRF7 to promote IFNB1 transcription, leading to the inhibition of breast cancer progression. Taken together, our finding uncovers a vital role of RBM45 in modulating type I interferon signaling and cancer aggressive progression, implicating RBM45 as a potential therapeutic target in breast cancer.
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Neoplasias da Mama , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Fator Regulador 7 de Interferon , Proteínas de Ligação a RNA , Sumoilação , Humanos , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Feminino , Animais , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Fator Regulador 7 de Interferon/genética , Fator Regulador 7 de Interferon/metabolismo , Camundongos , Transcrição Gênica , Linhagem Celular Tumoral , Interferon beta/metabolismo , Interferon beta/genética , Transdução de Sinais , Camundongos Nus , Proliferação de Células , Proteína 28 com Motivo Tripartido/metabolismo , Proteína 28 com Motivo Tripartido/genética , Ensaios Antitumorais Modelo de Xenoenxerto , Camundongos Endogâmicos BALB CRESUMO
Increasing evidence suggests that deregulated RNA splicing factors play critical roles in tumorigenesis; however, their specific involvement in colon cancer remains largely unknown. Here we report that the splicing factor RBM25 is overexpressed in colon cancer, and this increased expression correlates with a poor prognosis of patients with colon cancer. Functionally, RBM25 ablation suppresses the growth of colon cancer cells both in vitro and in vivo. Mechanistically, our transcriptome-wide analysis of splicing events revealed that RBM25 regulates a large number of cancer-related alternative splicing events across the human genome in colon cancer. Particularly, RBM25 regulates the splicing of MNK2 by interacting with the poly G rich region in exon 14a, thereby inhibiting the selection of the proximal 3' splice site (ss), resulting in the production of the oncogenic short isoform, MNK2b. Knockdown of RBM25 leads to an increase in the MNK2a isoform and a decrease in the MNK2b isoform. Importantly, re-expression of MNK2b or blocking the 3' ss of the alternative exon 14a with ASO partially reverses the RBM25 knockdown mediated tumor suppression. Moreover, MNK2b levels were significantly increased in colon cancer tissues, which is positively correlated with the expression level of RBM25. Collectively, our findings uncover the critical role of RBM25 as a key splicing factor in colon cancer, suggesting its potential as a prognostic marker and therapeutic target.
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Aberrant alternative splicing is well-known to be closely associated with tumorigenesis of various cancers. However, the intricate mechanisms underlying breast cancer metastasis driven by deregulated splicing events remain largely unexplored. Here, we unveiled that RBM7 is decreased in lymph node and distant organ metastases of breast cancer as compared to primary lesions and low expression of RBM7 is correlated with the reduced disease-free survival of breast cancer patients. Breast cancer cells with RBM7 depletion exhibited an increased potential for lung metastasis compared to scramble control cells. The absence of RBM7 stimulated breast cancer cell migration, invasion, and angiogenesis. Mechanistically, RBM7 controlled the splicing switch of MFGE8, favoring the production of the predominant isoform of MFGE8, MFGE8-L. This resulted in the attenuation of STAT1 phosphorylation and alterations in cell adhesion molecules. MFGE8-L exerted an inhibitory effect on the migratory and invasive capability of breast cancer cells, while the truncated isoform MFGE8-S, which lack the second F5/8 type C domain had the opposite effect. In addition, RBM7 negatively regulates the NF-κB cascade and an NF-κB inhibitor could obstruct the increase in HUVEC tube formation caused by RBM7 silencing. Clinically, we noticed a positive correlation between RBM7 expression and MFGE8 exon7 inclusion in breast cancer tissues, providing new mechanistic insights for molecular-targeted therapy in combating breast cancer.
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Neoplasias da Mama , NF-kappa B , Proteínas de Ligação a RNA , Humanos , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Feminino , NF-kappa B/metabolismo , Movimento Celular/genética , Linhagem Celular Tumoral , Processamento Alternativo , Metástase Neoplásica , Transdução de Sinais , Animais , Regulação Neoplásica da Expressão Gênica , CamundongosRESUMO
Metastasis is the leading cause for the high mortality of lung cancer, however, effective anti-metastatic drugs are still limited. Here it is reported that the RNA-binding protein RBMS1 is positively associated with increased lymph node metastasis in non-small cell lung cancer (NSCLC). Depletion of RBMS1 suppresses cancer cell migration and invasion in vitro and inhibits cancer cell metastasis in vivo. Mechanistically, RBMS1 interacts with YTHDF1 to promote the translation of S100P, thereby accelerating NSCLC cell metastasis. The RRM2 motif of RBMS1 and the YTH domain of YTHDF1 are required for the binding of RBMS1 and YTHDF1. RBMS1 ablation inhibits the translation of S100P and suppresses tumor metastasis. Targeting RBMS1 with NTP, a small molecular chemical inhibitor of RBMS1, attenuates tumor metastasis in a mouse lung metastasis model. Correlation studies in lung cancer patients further validate the clinical relevance of the findings. Collectively, the study provides insight into the molecular mechanism by which RBMS1 promotes NSCLC metastasis and offers a therapeutic strategy for metastatic NSCLC.
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Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Animais , Camundongos , Humanos , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Neoplasias Pulmonares/metabolismo , Linhagem Celular Tumoral , Proteínas de Ligação a RNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Neoplasias/metabolismoRESUMO
The contribution of oncogenes to tumor-associated RNA splicing and the relevant molecular mechanisms therein require further elaboration. Here, we show that oncogenic Aurora kinase A (AURKA) promotes breast cancer-related RNA aberrant splicing in a context-dependent manner. AURKA regulated pan-breast cancer-associated RNA splicing events including GOLGA4, RBM4 and UBQLN1. Aberrant splicing of GOLGA4 and RBM4 was closely related to breast cancer development. Mechanistically, AURKA interacted with the splicing factor YBX1 and promoted AURKA-YBX1 complex-mediated GOLGA4 exon inclusion. AURKA binding to the splicing factor hnRNPK promoted AURKA-hnRNPK complex-mediated RBM4 exon skipping. Analysis of clinical data identified an association between the AURKA-YBX1/hnRNPK complex and poor prognosis in breast cancer. Blocking AURKA nuclear translocation with small molecule drugs partially reversed the oncogenic splicing of RBM4 and GOLGA4 in breast cancer cells. In summary, oncogenic AURKA executes its function on modulating breast cancer-related RNA splicing, and nuclear AURKA is distinguished as a hopeful target in the case of treating breast cancer.
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BACKGROUND: Sandhoff disease (SD, Online Mendelian Inheritance in Man: 268800) is an autosomal recessive lysosomal storage disorder caused by variants of the ß-hexosaminidase B (HEXB) gene (Online Mendelian Inheritance in Man: 606873). The HEXB gene has been mapped to chromosome 5q13 and contains 14 exons. The symptoms of SD include progressive weakness, intellectual disability, visual and hearing impairment, exaggerated startle response, and seizures; the patients usually die before the age of 3 years.[1]. CASE SUMMARY: We present a case of SD caused by a homozygous frameshift mutation in the HEXB gene, c.118delG (p.A40fs*24). The male child, aged 2 years 7 months, showed movement retrogression with orbital hypertelorism at age 2 years, accompanied by seizures. Magnetic resonance imaging of the head showed cerebral atrophy and delayed myelination of the white matter of the brain. CONCLUSION: A novel homozygous frameshift c.118delG (p.A40fs*24) variant of HEXB has caused SD in the child. The major symptoms are intellectual disability, visual and hearing impairment, and seizures. Investigation will be continued in the future to comprehensively describe the genotype/phenotype and gain information on other associated features to understand the variable expressivity of this condition.
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Deficiência Intelectual , Doença de Sandhoff , Humanos , Masculino , Cadeia beta da beta-Hexosaminidase/genética , beta-N-Acetil-Hexosaminidases/genética , Mutação da Fase de Leitura , Hexosaminidase B/genética , Mutação , Doença de Sandhoff/diagnóstico , Doença de Sandhoff/genética , Convulsões , Pré-EscolarRESUMO
INTRODUCTION: Citrin is a calcium-bound aspartate-glutamate carrier protein encoded by the gene SLC25A13, mutations of which can cause citrin deficiency, an autosomal recessive disorder. The manifestations of citrin deficiency include neonatal intrahepatic choledeposits caused by citrin deficiency (NICCD: OMIM#605814), intermediate growth disorders and dyslipidemia caused by citrin deficiency, and citrullinemia type II (OMIM#603471) in adults. NICCD is a classical metabolic disorder that causes cholestasis in newborns. PATIENT CONCERN AND CLINICAL FINDINGS: Here, we present the case of a 2-month-old male patient treated in our hospital on March 20, 2023, due to "postnatal skin xanthochromia and transaminases higher than normal values". Since birth, the child's skin had yellowed all over the body, and his condition did not improve after multiple medical treatments. DIAGNOSIS/INTERVENTION/OUTCOMES: The child underwent full exome gene testing at the age of 2 months and 13 days, and the results indicated heterozygous deletion of exon 3 of the SLC25A13 gene, while genetic testing of the parents revealed no gene mutations. The variant was preliminarily judged as being pathogenic according to the ACMG guidelines, and the patient was diagnosed with "citrin deficiency". Skin yellowing eventually subsided, and liver function returned to normal without special treatment. CONCLUSIONS: Here, we report a rare case of citrin deficiency caused by a heterozygous deletion of the SLC25A13 gene. This case increases the clinical phenotypic profile of NICCD, suggesting that clinicians must be vigilant regarding such genetic metabolic diseases in the clinic for early diagnosis and treatment. NICCD should always be considered in the differential diagnosis of neonatal cholestasis.
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Colestase Intra-Hepática , Colestase , Citrulinemia , Transportadores de Ânions Orgânicos , Lactente , Criança , Adulto , Recém-Nascido , Humanos , Masculino , Citrulinemia/diagnóstico , Citrulinemia/genética , Mutação , Colestase/complicações , Éxons/genética , China , Colestase Intra-Hepática/diagnóstico , Proteínas de Ligação ao Cálcio/genética , Transportadores de Ânions Orgânicos/genética , Proteínas de Transporte da Membrana Mitocondrial/genéticaRESUMO
BACKGROUND: TBL1XR1, also known as IRA1 or TBLR1, encodes a protein that is localized in the nucleus and is expressed in most tissues. TBL1XR1 binds to histones H2B and H4 in vitro and functions in nuclear receptor-mediated transcription. TBL1XR1 is also involved in the regulation of the Wnt-ß-catenin signaling pathway. Mutations in the TBL1XR1 gene impair the Wnt-ß-catenin signaling pathway's ability to recruit Wnt-responsive element chromatin, affecting brain development. Mutations in this gene cause various clinical phenotypes, including Pierpont syndrome, autism spectrum disorder, speech and motor delays, mental retardation, facial dysmorphism, hypotonia, microcephaly, and hearing impairment. CASE SUMMARY: A 5-month-old female child was admitted with "episodic limb tremors for more than 1 month." At the time of admission, the child had recurrent episodes of limb tremors with motor retardation and a partially atypical and hypsarrhythmic video electroencephalogram. It was determined that a heterozygous mutation in the TBL1XR1 gene caused West syndrome and global developmental delay. Recurrent episodes persisted for 6 months following oral treatment with topiramate; the addition of oral treatment with vigabatrin did not show any significant improvement, and the disease continued to recur. The child continued to have recurrent episodes of limb tremors at follow-up until 1 year and 3 months of age. Additionally, she developed poor eye contact and a poor response to name-calling. CONCLUSION: We report the case of a child with West syndrome and a global developmental delay caused by a heterozygous mutation in the TBL1XR1 gene. This study adds to our understanding of the clinical phenotype of TBL1XR1 mutations and provides a realistic and reliable basis for clinicians.
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Transtorno do Espectro Autista , Espasmos Infantis , Humanos , Criança , Feminino , beta Catenina/genética , Tremor , Mutação , Proteínas Repressoras/metabolismo , Receptores Citoplasmáticos e Nucleares/genéticaRESUMO
RATIONALE: Retinitis pigmentosa with or without skeletal abnormalities (RPSKA) is an autosomal recessive disorder caused by mutations in the CWC27 gene. Skeletal dysplasia and non-syndromic retinitis pigmentosa are typical manifestations, and most patients present with retinopathy such as retinitis pigmentosa and limited visual field. Its clinical manifestations are complex and diverse, often involving multiple systems. Examples include short finger deformities, peculiar facial features, short stature, and neurodevelopmental abnormalities, and it is easy to misdiagnose clinically, and early diagnosis is crucial for prognosis. PATIENT CONCERNS: A 2-year and 2-month-old female child was admitted to the hospital due to "unsteady walking alone and slow reaction for more than half a year." After admission, the child was found to have delayed motor development, accompanied by special face, abnormal physical examination of the nervous system, cranial MRI Dandy-Walker malformation, considering developmental delay. DIAGNOSES: Whole exome sequencing of the family line revealed the presence of a c.617(exon7)C>A pure mutation in the CWC27 gene in the affected child (this locus has been reported in the clinical literature); the final diagnosis is RPSKA. INTERVENTIONS: Unfortunately, there is no specific drug for the disease; we give children rehabilitation training treatment. OUTCOMES: During follow-up process we found that children's condition is better than before. LESSONS SUBSECTIONS AS PER STYLE: We reported a case of RPSKA caused by mutations in the CWC27 gene. This study adds to our understanding of the clinical phenotype of TBL1XR1 mutations and provides a realistic and reliable basis for clinicians.
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Ciclofilinas , Retinose Pigmentar , Criança , Feminino , Humanos , Lactente , Homozigoto , Mutação , Linhagem , Fenótipo , Retinose Pigmentar/diagnóstico , Retinose Pigmentar/genética , Ciclofilinas/genéticaRESUMO
AIMS: Oral squamous cell carcinoma (OSCC) is considered as the sixth most common cancer worldwide characterized by high invasiveness, high metastasis rate and high mortality. It is urgent to explore novel therapeutic strategies to overcome this feature. Metformin is currently a strong candidate anti-tumor drug in multiple cancers. However, whether metformin could inhibit cancer progression by regulating RNA alternative splicing remains largely unknown. MAIN METHODS: Cell proliferation and growth ability of CAL-27 and UM-SCC6 were analyzed by CCK8 and colony formation assays. Cell migration was judged by wound healing assay. Mechanistically, RNA-seq was applied to systematically identify genes that are regulated by metformin. The expression of metformin-regulated genes was determined by real-time quantitative PCR (RT-qPCR). Metformin-regulated alternative splicing events were confirmed by RT-PCR. KEY FINDINGS: We demonstrated that metformin could significantly inhibit the proliferation and migration of oral squamous cell carcinoma cells. Mechanistically, in addition to transcriptional regulation, metformin induces a wide range of alternative splicing alteration, including genes involved in centrosome, cellular response to DNA damage stimulus, GTPase binding, histone modification, catalytic activity, regulation of cell cycle process and ATPase complex. Notably, metformin specifically modulates the splicing of NUBP2, a component of the cytosolic iron-sulfur (Fe/S) protein assembly (CIA). Briefly, metformin favors the production of NUBP2-L, the long splicing isoform of NUBP2, thereby inhibiting cancer cell proliferation. SIGNIFICANCE: Our findings provide mechanistic insights of metformin on RNA alternative splicing regulation, thus to offer a potential novel route for metformin to inhibit cancer progression.
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Carcinoma de Células Escamosas , Neoplasias de Cabeça e Pescoço , Metformina , Neoplasias Bucais , Humanos , Carcinoma de Células Escamosas/tratamento farmacológico , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Carcinoma de Células Escamosas de Cabeça e Pescoço/genética , RNA/metabolismo , Neoplasias Bucais/tratamento farmacológico , Neoplasias Bucais/genética , Neoplasias Bucais/metabolismo , Processamento Alternativo , Metformina/farmacologia , Metformina/uso terapêutico , Proliferação de Células , Neoplasias de Cabeça e Pescoço/genética , Linhagem Celular Tumoral , Movimento Celular , Regulação Neoplásica da Expressão GênicaRESUMO
Cellular senescence serves as a powerful tumor suppressing mechanism that inhibits the proliferation of cancer cells bearing oncogenic mutations at the initial stage of cancer development. RNA-binding proteins (RBPs) play important roles in cancer progression and treatment through distinct functions. However, functions and mechanisms of RNA binding proteins in regulating senescence remain elusive. Here we reported that the RNA binding protein RBM4 contributed to cellular senescence. Depletion of RBM4 induced senescence in different types of cells, including multiple cancer cells. Meanwhile, RBM4 ablation inhibited cancer cell progression both in vitro and in vivo. Specifically, knockdown of RBM4 significantly increased the level of SERPINE1, a known promoter of senescence, thereby inducing the senescence of lung cancer cells. Mechanistically, miR-1244 bound to the 3'-UTR of SERPINE1 to suppress its expression, whereas depletion of RBM4 reduced the level of miR-1244 by promoting the degradation of primary miR-1244 transcripts (pri-miR1244), thus increasing the expression of SERPINE1 and inducing subsequent senescence. Moreover, either SERPINE1 inhibitor or miR-1244 mimics attenuated the RBM4 depletion-induced senescence. Altogether, our study revealed a novel mechanism of RBM4 in the regulation of cancer progression through controlling senescence, providing a new avenue for targeting RBM4 in cancer therapeutics.
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Neoplasias Pulmonares , MicroRNAs , Humanos , Processamento Alternativo , Senescência Celular/genética , MicroRNAs/genética , MicroRNAs/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , Inibidor 1 de Ativador de Plasminogênio/genética , Inibidor 1 de Ativador de Plasminogênio/metabolismoRESUMO
Cellular senescence provides a protective barrier against tumorigenesis in precancerous or normal tissues upon distinct stressors. However, the detailed mechanisms by which tumor cells evade premature senescence to malignant progression remain largely elusive. Here we reported that RBM4 adversely impacted cellular senescence to favor glutamine-dependent survival of esophageal squamous cell carcinoma (ESCC) cells by dictating the activity of LKB1, a critical governor of cancer metabolism. The level of RBM4 was specifically elevated in ESCC compared to normal tissues, and RBM4 overexpression promoted the malignant phenotype. RBM4 contributed to overcome H-RAS- or doxorubicin-induced senescence, while its depletion caused P27-dependent senescence and proliferation arrest by activating LKB1-AMPK-mTOR cascade. Mechanistically, RBM4 competitively bound LKB1 to disrupt the LKB1/STRAD/MO25 heterotrimeric complex, subsequently recruiting the E3 ligase TRIM26 to LKB1, promoting LKB1 ubiquitination and degradation in nucleus. Therefore, such molecular process leads to bypassing senescence and sustaining cell proliferation through the activation of glutamine metabolism. Clinically, the ESCC patients with high RBM4 and low LKB1 have significantly worse overall survival than those with low RBM4 and high LKB1. The RBM4 high/LKB1 low expression confers increased sensitivity of ESCC cells to glutaminase inhibitor CB-839, providing a novel insight into mechanisms underlying the glutamine-dependency to improve the efficacy of glutamine inhibitors in ESCC therapeutics.
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Neoplasias Esofágicas , Carcinoma de Células Escamosas do Esôfago , Humanos , Quinases Proteína-Quinases Ativadas por AMP , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Senescência Celular/genética , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/patologia , Carcinoma de Células Escamosas do Esôfago/genética , Glutamina/genética , Glutamina/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas de Ligação a RNA , Proteínas com Motivo Tripartido/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Hepatocellular carcinoma (HCC) is one of the most common primary cancers with limited therapeutic options. Melatonin, a neuroendocrine hormone produced primarily by the pineal gland, demonstrates an anti-cancer effect on a myriad of cancers including HCC. However, whether melatonin could suppress tumor growth through regulating RNA alternative splicing remains largely unknown. Here we demonstrated that melatonin could inhibit the growth of HCC. Mechanistically, melatonin induced transcriptional alterations of genes, which are involved in DNA replication, DNA metabolic process, DNA repair, response to wounding, steroid metabolic process, and extracellular matrix functions. Importantly, melatonin controlled numerous cancer-related RNA alternative splicing events, regulating mitotic cell cycle, microtubule-based process, kinase activity, DNA metabolic process, GTPase regulator activity functions. The regulatory effect of melatonin on alternative splicing is partially mediated by melatonin receptor MT1. Specifically, melatonin regulates the splicing of IKBKG (NEMO), an essential modulator of NF-κB. In brief, melatonin increased the production of the long isoform of NEMO-L with exon 5 inclusion, thereby inhibiting the growth of HepG2 cells. Collectively, our study provides a novel mechanism of melatonin in regulating RNA alternative splicing, and offers a new perspective for melatonin in the inhibition of cancer progression.
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Immunotherapy has been widely utilized in multiple tumors, however, its efficacy in the treatment of triple-negative breast cancers (TNBC) is still being challenged. Meanwhile, functions and mechanisms of RNA binding proteins in regulating immunotherapy for TNBC remain largely elusive. Here we reported that the RNA binding protein RBMS1 is prevalent among immune-cold TNBC. Through a systematic shRNA-mediated screen, we found depletion of RBMS1 significantly reduced the level of programmed death ligand 1 (PD-L1) in TNBC. Clinically, RBMS1 was increased in breast cancer and its level was positively correlated to that of PD-L1. RBMS1 ablation stimulated cytotoxic T cell mediated anti-tumor immunity. Mechanistically, RBMS1 regulated the mRNA stability of B4GALT1, a newly identified glycosyltransferase of PD-L1. Depletion of RBMS1 destabilized the mRNA of B4GALT1, inhibited the glycosylation of PD-L1 and promoted the ubiquitination and subsequent degradation of PD-L1. Importantly, combination of RBMS1 depletion with CTLA4 immune checkpoint blockade or CAR-T treatment enhanced anti-tumor T-cell immunity both in vitro and in vivo. Together, our findings provided a new immunotherapeutic strategy against TNBC by targeting the immunosuppressive RBMS1.
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Antígeno B7-H1 , Neoplasias de Mama Triplo Negativas , Humanos , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Neoplasias de Mama Triplo Negativas/metabolismo , Imunoterapia , Anticorpos/uso terapêutico , RNA Interferente Pequeno/uso terapêutico , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a RNARESUMO
Aberrant RNA splicing produces alternative isoforms of genes to facilitate tumor progression, yet how this process is regulated by oncogenic signal remains largely unknown. Here, we unveil that non-canonical activation of nuclear AURKA promotes an oncogenic RNA splicing of tumor suppressor RBM4 directed by m6A reader YTHDC1 in lung cancer. Nuclear translocation of AURKA is a prerequisite for RNA aberrant splicing, specifically triggering RBM4 splicing from the full isoform (RBM4-FL) to the short isoform (RBM4-S) in a kinase-independent manner. RBM4-S functions as a tumor promoter by abolishing RBM4-FL-mediated inhibition of the activity of the SRSF1-mTORC1 signaling pathway. Mechanistically, AURKA disrupts the binding of SRSF3 to YTHDC1, resulting in the inhibition of RBM4-FL production induced by the m6A-YTHDC1-SRSF3 complex. In turn, AURKA recruits hnRNP K to YTHDC1, leading to an m6A-YTHDC1-hnRNP K-dependent exon skipping to produce RBM4-S. Importantly, the small molecules that block AURKA nuclear translocation, reverse the oncogenic splicing of RBM4 and significantly suppress lung tumor progression. Together, our study unveils a previously unappreciated role of nuclear AURKA in m6A reader YTHDC1-dependent oncogenic RNA splicing switch, providing a novel therapeutic route to target nuclear oncogenic events.
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Processamento Alternativo , Aurora Quinase A , Proteínas do Tecido Nervoso , Fatores de Processamento de RNA , Proteínas de Ligação a RNA , Aurora Quinase A/genética , Aurora Quinase A/metabolismo , Núcleo Celular/genética , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Splicing de RNA , Fatores de Processamento de RNA/genética , Fatores de Processamento de RNA/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismoRESUMO
Background: A large number of circular RNAs (circRNAs) have been discovered in the mammalian transcriptome with high abundance, which play vital roles in gene regulation, thereby participating in the development of multiple diseases. However, the biogenesis, regulation, and especially manipulation of circRNAs still remain largely unknown. Methods: Engineering circRNA regulators (ECRRs) were developed to promote circRNA biogenesis. Multiple circRNA mini-gene reporters were generated to evaluate the regulatory role of ECRRs. RT-PCR, qRT-PCR, northern blot, western blot, and flow cytometry assays were applied to assess the efficiency of artificial circRNA regulators on circRNA production in the presence or absence of RNase R treatment. Results: We engineered circRNA regulators by combining sequence-specific RNA binding motifs of human Pumilio 1 with functional domains that could form dimerization. We applied these engineered regulators to promote the circRNA production of the exogenous circRNA minigene reporter circGFP, thereby stimulating the functional GFP protein generation. Crucially, such regulation is in time-course dependent and dose-dependent manners with designed specificity. Moreover, the application of ECRRs could also stimulate circRNA biogenesis of another minigene reporter circScreen, suggesting that ECRRs can be commonly used to promote circRNA generation of exogenous reporters. Most importantly, ECRRs could be utilized to specifically promote the production of the endogenous circRNAs circ10720 and circBIRC6 as well. Conclusion: Our approach allows the creation of engineered regulators to target virtually any pre-mRNA in vivo, offering a novel avenue to investigate circRNA biogenesis and manipulate disease-related circRNA production.
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Regulação da Expressão Gênica , Engenharia Genética , Motivos de Nucleotídeos , RNA Circular , Proteínas de Ligação a RNA , Fatores de Transcrição , Células HEK293 , Células HeLa , Humanos , RNA Circular/biossíntese , RNA Circular/genética , Proteínas de Ligação a RNA/biossíntese , Proteínas de Ligação a RNA/genética , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genéticaRESUMO
Liquid-liquid phase separation is considered a generic approach to organize membrane-less compartments, enabling the dynamic regulation of phase-separated assemblies to be investigated and pivotal roles of protein posttranslational modifications to be demonstrated. By surveying the subcellular localizations of human deubiquitylases, USP42 was identified to form nuclear punctate structures that are associated with phase separation properties. Bioinformatic analysis demonstrated that the USP42 C-terminal sequence was intrinsically disordered, which was further experimentally confirmed to confer phase separation features. USP42 is distributed to SC35-positive nuclear speckles in a positively charged C-terminal residue- and enzymatic activity-dependent manner. Notably, USP42 directs the integration of the spliceosome component PLRG1 into nuclear speckles, and its depletion interferes with the conformation of SC35 foci. Functionally, USP42 downregulation deregulates multiple mRNA splicing events and leads to deterred cancer cell growth, which is consistent with the impact of PLRG1 repression. Finally, USP42 expression is strongly correlated with that of PLRG1 in non-small-cell lung cancer samples and predicts adverse prognosis in overall survival. As a deubiquitylase capable of dynamically guiding nuclear speckle phase separation and mRNA splicing, USP42 inhibition presents a novel anticancer strategy by targeting phase separation.
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Carcinogênese/metabolismo , Extração Líquido-Líquido/métodos , Salpicos Nucleares/metabolismo , Splicing de RNA/genética , Tioléster Hidrolases/genética , Transfecção/métodos , HumanosRESUMO
Alternative splicing is a critical process to generate protein diversity. However, whether and how alternative splicing regulates autophagy remains largely elusive. Here we systematically identify the splicing factor SRSF1 as an autophagy suppressor. Specifically, SRSF1 inhibits autophagosome formation by reducing the accumulation of LC3-II and numbers of autophagosomes in different cell lines. Mechanistically, SRSF1 promotes the splicing of the long isoform of Bcl-x that interacts with Beclin1, thereby dissociating the Beclin1-PIK3C3 complex. In addition, SRSF1 also directly interacts with PIK3C3 to disrupt the interaction between Beclin1 and PIK3C3. Consequently, the decrease of SRSF1 stabilizes the Beclin1 and PIK3C3 complex and activates autophagy. Interestingly, SRSF1 can be degraded by starvation- and oxidative stresses-induced autophagy through interacting with LC3-II, whereas reduced SRSF1 further promotes autophagy. This positive feedback is critical to inhibiting Gefitinib-resistant cancer cell progression both in vitro and in vivo. Consistently, the expression level of SRSF1 is inversely correlated to LC3 level in clinical cancer samples. Our study not only provides mechanistic insights of alternative splicing in autophagy regulation but also discovers a new regulatory role of SRSF1 in tumorigenesis, thereby offering a novel avenue for potential cancer therapeutics.
Assuntos
Classe III de Fosfatidilinositol 3-Quinases/genética , Neoplasias Pulmonares/genética , Proteínas Associadas aos Microtúbulos/genética , Fatores de Processamento de Serina-Arginina/genética , Proteína bcl-X/genética , Células A549 , Processamento Alternativo/genética , Animais , Autofagossomos/genética , Autofagia/genética , Carcinogênese/genética , Regulação Neoplásica da Expressão Gênica/genética , Xenoenxertos , Humanos , Neoplasias Pulmonares/patologia , CamundongosRESUMO
Ferroptosis, an iron-dependent nonapoptotic cell death, is a highly regulated tumor suppressing process. However, functions and mechanisms of RNA-binding proteins in regulation of evasion of ferroptosis during lung cancer progression are still largely unknown. Here, we report that the RNA-binding protein RBMS1 participates in lung cancer development via mediating ferroptosis evasion. Through an shRNA-mediated systematic screen, we discovered that RBMS1 is a key ferroptosis regulator. Clinically, RBMS1 was elevated in lung cancer and its high expression was associated with reduced patient survival. Conversely, depletion of RBMS1 inhibited lung cancer progression both in vivo and in vitro. Mechanistically, RBMS1 interacted with the translation initiation factor eIF3d directly to bridge the 3'- and 5'-UTR of SLC7A11. RBMS1 ablation inhibited the translation of SLC7A11, reduced SLC7A11-mediated cystine uptake, and promoted ferroptosis. In a drug screen that targeted RBMS1, we further uncovered that nortriptyline hydrochloride decreased the level of RBMS1, thereby promoting ferroptosis. Importantly, RBMS1 depletion or inhibition by nortriptyline hydrochloride sensitized radioresistant lung cancer cells to radiotherapy. Our findings established RBMS1 as a translational regulator of ferroptosis and a prognostic factor with therapeutic potential and clinical value.