RBM41 Drives Colorectal Cancer by Blocking NDRG1 Pre-mRNA Maturation, Study Reveals
核心洞察
RBM41 (搜索) is significantly overexpressed in colorectal cancer (搜索) tissues and its high expression correlates with poor patient prognosis, including shorter disease-free and overall survival.
Mechanistically, RBM41 (搜索) binds a stem-loop structure containing a GCAAUGA motif in the 3′UTR of NDRG1 (搜索) pre-mRNA, impeding its maturation and reducing tumor suppressor NDRG1 protein levels.
RBM41 (搜索) deficiency triggers synergistic cell death through concurrent apoptosis activation and autophagic flux blockade, with both pathways operating independently.
Researchers have identified RNA binding motif protein 41 (RBM41 (搜索)) as a potent oncogenic driver in colorectal cancer (搜索) (CRC), revealing a novel post-transcriptional mechanism by which this underappreciated protein blocks the maturation of the tumor suppressor NDRG1 (搜索) pre-mRNA. The findings, published in Cell Death Discovery, establish the RBM41-NDRG1 axis as both a prognostic biomarker and a promising therapeutic vulnerability in one of the world's most lethal malignancies.
RBM41 (搜索) Overexpression Correlates with Poor Prognosis
Analysis of public databases revealed that RBM41 (搜索) is aberrantly overexpressed across multiple cancer types, with significantly higher expression in CRC tissues compared to adjacent normal tissues in both unpaired and paired comparisons. Survival analysis demonstrated that patients with high RBM41 expression experience shorter disease-free survival and overall survival compared to those with lower RBM41 levels. Receiver operating characteristic (ROC) curve analysis supported the diagnostic relevance of RBM41, yielding an area under the curve (AUC) of 0.726.
Validation in clinical samples from five CRC patients confirmed that both mRNA and protein levels of RBM41 (搜索) were markedly upregulated in tumor tissues compared to matched adjacent tissues in four of five cases. Immunohistochemical analysis further revealed enhanced Ki-67 staining in tumor tissues from four cases, linking RBM41 expression to proliferative activity.
RBM41 (搜索) Promotes Proliferation and Suppresses Cell Death
Functional studies in CRC cell lines demonstrated that RBM41 (搜索) is highly expressed in T84 and HT29 cells and lowest in SW480 cells. Knockdown of RBM41 in HT29 and T84 cells significantly inhibited cell proliferation, viability, and clonogenic ability while markedly increasing apoptosis. Conversely, overexpression of RBM41 in SW480 cells accelerated proliferation, enhanced clonogenic capacity, and improved cell survival, confirming its role as an oncogene.
Synergistic Lethality Through Apoptosis and Autophagic Blockade
Mechanistic dissection using pharmacological inhibitors revealed that only the autophagy inhibitor chloroquine (CQ) and the apoptosis inhibitor Z-VAD-FMK significantly rescued the decreased cell viability caused by RBM41 (搜索) knockdown, while ferroptosis and necroptosis inhibitors had minimal effects. RBM41 knockdown concurrently upregulated Bax, downregulated BCL2, and increased the LC3B-II/LC3B-I ratio alongside P62 accumulation, confirming both apoptosis activation and autophagic flux impairment.
Transmission electron microscopy confirmed abundant autophagosome accumulation rather than autolysosomes in RBM41 (搜索)-deleted cells, and lysosome-sensitive fluorescent probes demonstrated impaired autophagosome-lysosome fusion, indicating late-stage autophagic flux disruption. Notably, autophagy-related marker changes occurred prior to apoptosis-related protein alterations, yet inhibiting one pathway did not reverse changes in the other. Only simultaneous inhibition of both pathways restored cell viability to the greatest extent, demonstrating that apoptosis and disrupted autophagy function through independent mechanisms to exert synergistic lethal effects.
RBM41 (搜索) Binds a Stem-Loop Structure in NDRG1 (搜索) Pre-mRNA
Transcriptome sequencing of RBM41 (搜索)-knockout cells identified NDRG1 (搜索) as markedly upregulated. As an RNA-binding protein predominantly localized in the nucleus, RBM41 was found to negatively regulate NDRG1 expression post-transcriptionally—without affecting mRNA stability or transcription. Instead, RBM41 knockdown led to a significant reduction in NDRG1 pre-mRNA levels accompanied by increased mature mRNA, indicating that RBM41 impedes pre-mRNA processing.
RNA immunoprecipitation confirmed that RBM41 (搜索) exhibits stronger binding affinity for NDRG1 (搜索) pre-mRNA than mature transcript. Further mapping localized the interaction to the 3′UTR, where RBM41 recognizes a specific stem-loop structure containing a GCAAUGA motif. Mutant variants disrupting this motif abolished RBM41 binding, confirming the structural basis of this regulatory interaction.
NDRG1 (搜索) Is the Key Effector of RBM41 (搜索)-Mediated Oncogenesis
Rescue experiments demonstrated that simultaneous knockdown of NDRG1 (搜索) in RBM41 (搜索)-deletion CRC cells reversed the upregulation of NDRG1, ameliorated aberrant apoptosis and autophagy marker expression, and significantly restored cell survival. Conversely, NDRG1 overexpression counteracted the pro-survival effects of RBM41 in RBM41-overexpressing cells.
In vivo xenograft models confirmed these findings: RBM41 (搜索)-knockout HT29 tumors showed significantly slowed growth with reduced tumor volume and weight at day 27, an effect reversed by simultaneous NDRG1 (搜索) knockout. In SW480 xenografts, RBM41 overexpression promoted tumor growth, which was counteracted by NDRG1 co-overexpression. Immunofluorescence co-staining confirmed that tumor areas with highest proliferative activity exhibited high RBM41 and low NDRG1 expression.
Clinical Implications and Chemotherapy Resistance
Analysis of patient-derived organoids (PDOs) recapitulated the negative correlation between RBM41 (搜索) and NDRG1 (搜索) expression observed in parental tumors. PDOs with high RBM41 expression exhibited significantly higher IC₅₀ values for three first-line chemotherapeutic agents, and RBM41 expression levels positively correlated with IC₅₀ values, indicating that elevated RBM41 is associated with increased chemoresistance.
The authors acknowledge several limitations, including the small clinical sample size, incomplete understanding of upstream regulatory mechanisms driving RBM41 (搜索) overexpression, and the need for comprehensive identification of RBM41's full RNA target repertoire using techniques such as CLIP-seq. Future studies should prioritize large-scale multicenter cohort validation and fine mapping of the RNA-binding domain.
These findings establish RBM41 (搜索) as a novel oncogenic RNA-binding protein that drives CRC progression through recognition of RNA secondary structure to regulate pre-mRNA processing, providing a new theoretical foundation for molecular subtyping and targeted therapy in colorectal cancer (搜索).