IGF2BP1 Promotes Proliferation of Neuroendocrine Neoplasms by Post-Transcriptional Enhancement of EZH2

A Mettl16/m6A/mybl2b/Igf2bp1 axis ensures cell cycle progression of embryonic hematopoietic stem and progenitor cells

Prenatal lethality associated with mouse knockout of Mettl16, a recently identified RNA N6-methyladenosine (m6A) methyltransferase, has hampered characterization of the essential role of METTL16-mediated RNA m6A modification in early embryonic development. Here, using cross-species single-cell RNA sequencing analysis, we found that during early embryonic development, METTL16 is more highly expressed in vertebrate hematopoietic stem and progenitor cells (HSPCs) than other methyltransferases. In Mettl16-deficient zebrafish, proliferation capacity of embryonic HSPCs is compromised due to G1/S cell cycle arrest, an effect whose rescue requires Mettl16 with intact methyltransferase activity. We further identify the cell-cycle transcription factor mybl2b as a directly regulated by Mettl16-mediated m6A modification. Mettl16 deficiency resulted in the destabilization of mybl2b mRNA, likely due to lost binding by the m6A reader Igf2bp1 in vivo. Moreover, we found that the METTL16-m6A-MYBL2-IGF2BP1 axis controlling G1/S progression is conserved in humans. Collectively, our findings elucidate the critical function of METTL16-mediated m6A modification in HSPC cell cycle progression during early embryonic development.

A review of nuclear Dbf2-related kinase 1 (NDR1) protein interaction as promising new target for cancer therapy

Nuclear Dbf2-related kinase 1 (NDR1) is a nuclear Dbf2-related (NDR) protein kinase family member, which regulates cell functions and participates in cell proliferation and differentiation through kinase activity. NDR1 regulates physiological functions by interacting with different proteins. Protein-protein interactions (PPIs) are crucial for regulating biological processes and controlling cell fate, and as a result, it is beneficial to study the actions of PPIs to elucidate the pathological mechanism of diseases. The previous studies also show that the expression of NDR1 is deregulated in numerous human cancer samples and it needs the context-specific targeting strategies for NDR1. Thus, a comprehensive understanding of the direct interaction between NDR1 and varieties of proteins may provide new insights into cancer therapies. In this review, we summarize recent studies of NDR1 in solid tumors, such as prostate cancer and breast cancer, and explore the mechanism of action of PPIs of NDR1 in tumors.

CRD-BP as a Tumor Marker of Colorectal Cancer

The National Cancer Center published a comparative report on cancer data between China and the United States in the Chinese Medical Journal, which shows that colorectal cancer (CRC) ranks second in China and fourth in the United States. It is worth noting that since 2000, the case fatality rate of CRC in China has skyrocketed, while the United States has gradually declined. Finding tumor markers with high sensitivity and specificity is our primary goal to reduce the case fatality rate of CRC. Studies have shown that CRD-BP (Insulin-like growth factor 2 mRNA-binding protein 1) can affect a variety of signaling pathways, such as Wnt.nuclear factor KB (NF-κB), and Hedgehog, and has good biological effects as a therapeutic target for CRC. CRD-BP is expected to become a tumor marker with high sensitivity and specificity of CRC. This paper reviews the research on CRD-BP as a tumor marker of CRC.

The m6A reader IGF2BP1 manipulates BUB1B expression to affect malignant behaviors, stem cell properties, and immune resistance of non-small-cell lung cancer stem cells

N6-methyladenosine (m6A) modification is the most common internal modification in eukaryotic mRNA and an important mechanism for post-transcriptional regulation of genes. This study focuses on the role of the m6A reader insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) in the malignant behaviors of non-small-cell lung cancer (NSCLC) cells and especially the cancer stem cells (CSCs). We obtained IGF2BP1 as an aberrantly upregulated gene linking to poor survival of patients with NSCLC by bioinformatics, and then confirmed increased IGF2BP1 expression in NSCLC tissues and cells, especially in the enriched CSCs. Knockdown of IGF2BP1 suppressed proliferation, mobility and epithelial-mesenchymal transition activity of NSCLC cells and CSCs, and it reduced stemness, self-renewal ability, xenograft tumorigenesis and immune resistance of the CSCs. IGF2BP1 was predicted to have a positive correlation with BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B), and it upregulated BUB1B expression through m6A modification. Further overexpression of BUB1B in CSCs counteracted the effects of IGF2BP1 silencing and restored the malignant phenotype, self-renewal, and immune resistance of CSCs in vitro and in vivo. Taken together, this work demonstrates that IGF2BP1 manipulates BUB1B expression to affect malignant behaviors, stem cell properties and immune resistance of NSCLC stem cells.

Inhibition of IGF2BP1 attenuates renal injury and inflammation by alleviating m6A modifications and E2F1/MIF pathway

Septic acute kidney injury (AKI) is characterized by inflammation. Pyroptosis often occurs during AKI and is associated with the development of septic AKI. This study found that induction of insulin-like growth factor 2 mRNA binding protein 1 (IGF2BP1) to a higher level can induce pyroptosis in renal tubular cells. Meanwhile, macrophage migration inhibitory factor (MIF), a subunit of NLRP3 inflammasomes, was essential for IGF2BP1-induced pyroptosis. A putative m6A recognition site was identified at the 3'-UTR region of E2F transcription factor 1 (E2F1) mRNA via bioinformatics analyses and validated using mutation and luciferase experiments. Further actinomycin D (Act D) chase experiments showed that IGF2BP1 stabilized E2F1 mRNA dependent on m6A. Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) indicated that E2F1 acted as a transcription factor to promote MIF expression. Thus, IGF2BP1 upregulated MIF through directly upregulating E2F1 expression via m6A modification. Experiments on mice with cecum ligation puncture (CLP) surgery verified the relationships between IGF2BP1, E2F1, and MIF and demonstrated the significance of IGF2BP1 in MIF-associated pyroptosis in vivo. In conclusion, IGF2BP1 was a potent pyroptosis inducer in septic AKI through targeting the MIF component of NLRP3 inflammasomes. Inhibiting IGF2BP1 could be an alternate pyroptosis-based treatment for septic AKI.

RNA binding protein IGF2BP1 meditates oxidative stress-induced granulosa cell dysfunction by regulating MDM2 mRNA stability in an m6A-dependent manner

Both genetic and microenvironmental detrimental factors are involved in ovarian dysfunction, leading to the increasing rate of involuntary childlessness in recent years. Oxidative stress (OS), which is characterized by the imbalance of redox system with redundant reactive oxygen species (ROS) overwhelming the antioxidant defense, is regarded as one of the culprits of ovarian dysfunction. OS causes damage to various types of ovarian cells including granulosa cells (GCs), jeopardizing the ovarian microenvironment, disturbing follicular development and participating in various female reproductive disorders. However, the specific molecular pathological mechanisms underlying this process have not been fully elucidated. In this study, we found that 3-nitropropionic acid (3-NP) treatment led to significant IGF2BP1 downregulation via, at least partially, inducing ROS overproduction. IGF2BP1 regulates GCs viability, proliferation, cell cycle and cellular senescence by enhancing MDM2 mRNA stability in an m6A-dependant manner. IGF2BP1 overexpression partially rescued 3-NP induced GCs damages, while ectopically expressed MDM2 alleviated both 3-NP or IGF2BP1-knockdown induced GCs dysfunction. These results reveal an epigenetic molecular mechanism underlying OS-related GCs disorders, which may help to establish a novel potential clinical marker for predicting the GCs status as well as the follicular developmental potential.

Enhancer of Zeste Homolog 2 (EZH2) Is a Marker of High-Grade Neuroendocrine Neoplasia in Gastroenteropancreatic and Pulmonary Tract and Predicts Poor Prognosis

Simple Summary

Neuroendocrine neoplasms most frequently arise in the gastroenteropancreatic and pulmonary tract and show an increasing incidence and prevalence. The prognosis and treatment depend on tumor proliferation and clinical behavior. Highly proliferating grade 3 neoplasms especially, show a wildly divergent therapy response and prognosis. In particular, it is crucial to securely separate the more indolent G3 tumors from the more aggressive carcinomas. Currently, this distinction is based on a combination of clinical, morphologic, immunohistochemical, and molecular biomarkers. However, none of these markers allow for a reliable distinction, and additional markers are needed. EZH2 has attracted increasing interest in different tumor entities. We aimed to analyze the expression of EZH2 in different neuroendocrine neoplasms and to correlate the expression with clinical parameters and survival. We demonstrate that EZH2 is nearly exclusively expressed in highly proliferative neoplasms and is a robust biomarker for identifying aggressive G3 tumors with poor prognosis.

Abstract

Tumor grading is a robust prognostic predictor in patients with neuroendocrine neoplasms (NEN) and guides therapy, especially in tumors with high proliferation. NEN can be separated into well-differentiated and poorly differentiated types. The more aggressive NEN have been further separated into neuroendocrine tumors (NET G3) with a better prognosis and neuroendocrine carcinomas (NEC) with a worse prognosis. Despite this distinction’s tremendous clinical and therapeutic relevance, optimal diagnostic biomarkers are still lacking. In this study, we analyzed the protein expression and prognostic impact of Enhancer of Zeste Homolog 2 (EZH2) by immunohistochemistry in 219 tissue samples of gastroenteropancreatic (GEP-NEN) and pulmonary NEN (P-NEN). EZH2 was almost exclusively expressed in NEN with a proliferation rate above 20% (G3), while all low-grade tumors were nearly negative. Among high-grade NEN, 65% showed high and 35% low expression of EZH2. In this group, the high expression of EZH2 was significantly associated with poor overall survival and NEC histology. Interestingly, EZH2 seems to act independently of Polycomb Repressive Complex 2 (PRC2) in NEN. In conclusion, we propose EZH2 as a robust biomarker for distinguishing between NET G3 and NEC among gastroenteropancreatic and pulmonary NEN.