Project description:The abnormal expression of m6A methyltransferase is a significant factor in the occurrence and progression of tumors. The 18S ribosomal RNA (rRNA) m6A methyltransferase Methyltransferase-like 5 (METTL5) is upregulated in various cancers, leading to adverse prognosis by abnormally regulating protein translation in tumor cells. However, the functionality and molecular mechanisms of METTL5 in the progression of multiple myeloma (MM) remains unknown. In this study, we demonstrate that the expression of METTL5 in the bone marrow (BM) of newly diagnosed MM patients is significantly higher than in healthy individuals and patients in remission following treatment. Importantly, we found that MM patients with upregulated METTL5 expression had a poorer prognosis. Additionally, we show that METTL5 plays a key role in promoting MM progression both in vitro and in a orthotopical xenograft model. Mechanistically, the depletion of METTL5 expression mediates a decrease in overall translation efficiency and selenium metabolism-related signaling pathway levels. We further revealed that the reduction in selenophosphate synthetase 2 (SEPHS2) translation efficiency mediated by METTL5 depletion can lead to diminished synthesis of selenoprotein and lead to increased reactive oxygen species (ROS), thereby inducing apoptosis in MM. Salvianolic Acid C (SAC) was identified as a potential METTL5 inhibitor, demonstrating significant pro-apoptotic effects during the treatment of MM both in vitro and in vivo. In summary, our research highlights the critical role of METTL5 in the progression of MM cells. Our data indicate METTL5’s function is to influence the overall translation efficiency and reprogram selenium metabolism to inhibit apoptosis.
Project description:Cellular protein synthesis occurs through two types of translation: cytoplasmic and mitochondrial. These two types of translation operate independently but in coordination to regulate cell survival and death. Methyltransferase-like 5 (METTL5) has been found to play a role in directing the m6A modification of rRNA, which in turn controls cytoplasmic translation and impacts the decisions related to cell fate. In this study, we employed Ribo-seq to explore the effects of METTL5 deficiency on both cytoplasmic and mitochondrial translation.
Project description:Tumor recurrence is main pattern of treatment failure for early-stage hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying disease recurrence remain poorly understood. Here, we showed that 18S rRNA N6-methyladenosine (m6A1832) modification and its methyltransferase complex METTL5/TRMT112 were upregulated in HCC and correlated with poor prognosis. Loss-of-function and gain-of-function assays demonstrated that METTL5/TRMT112 mediated 18S rRNA m6A1832 modification promotes HCC tumorigenesis in vitro and in vivo. Mechanistically, 18S rRNA m6A1832 modification selectively regulated the translation of mRNAs with long 5’UTR and short 3’UTR through affecting the assembly of 80S subunit at translation initiation and its dissociation at translation termination which was executed by weakening the interaction of ABCE1 with eRF1 and eRF3. Moreover, METTL5-mediated 18S rRNA m6A1832 modification regulated β-oxidation of long-chain fatty acid through ACSL4 to promote HCC progression. Our work uncovered a novel layer of mRNA translation regulation mechanism at ribosome 80S subunit assembly and dissociation step mediated by 18S rRNA m6A1832 modification and revealed a new crosslink between RNA epigenetic modification and fatty acid metabolism in HCC.
Project description:This work explores the therapeutic potential for the translation initiation factor eIF4E in multiple myeloma (MM). We show that targeting eIF4E is deleterious to MM cells and causes reduction of targets with established importance to the disease progression. We demonstrate that eIF4E inhibition may be achieved by treating the MM cells with the already clinically employed anti-viral drug Ribavirin. Results indicate that tetraspanin overexpression in MM cell lines increased global protein synthesis; CD81N1/CD82N1 also caused a decrease in peIF4E, its regulators and targets; direct inhibition of eIF4E (siRNA, Ribavirin) deleteriously affected MM cell lines; and Ribavirin attenuated viability and induced death of primary BM MM cells. Multiple Myeloma cell lines RPMI 8226 and CAG were each transiently transfected with purified plasmids of tetraspanins: pEGFP-N1 (N1, control), CD81N1-eGFP (81N1) or CD82N1-eGFP (82N1) (Clontech). Transfected cells were separated by Sorter Flow Cytometer 24 hours after transfection. Total RNA was extracted from sorted transfected cells with the Qiagen kit. Three separate experiments were analyzed by Whole Genome Affymetrix microarray chips (N1, 81N1, 82N1 in each cell line).
Project description:The paper describes a model of multiple myeloma.
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This model is described in the article:
A mathematical model of cell equilibrium and joint cell formation in multiple myeloma
M.A. Koenders, R. Saso
Journal of Theoretical Biology 390 (2016) 73–79
Abstract:
In Multiple Myeloma Bone Disease healthy bone remodelling is affected by tumour cells by means of paracrine cytokinetic signalling in such a way that osteoclast formation is enhanced and the growth of osteoblast cells inhibited. The participating cytokines are described in the literature. Osteoclast-induced myeloma cell growth is also reported. Based on existing mathematical models for healthy bone remo- delling a three-way equilibrium model is presented for osteoclasts, osteoblasts and myeloma cell populations to describe the progress of the illness in a scenario in which there is a secular increase in the cytokinetic interactive effectiveness of paracrine processes. The equilibrium state for the system is obtained. The paracrine interactive effectiveness is explored by parameter variation and the stable region in the parameter space is identified. Then recently-discovered joint myeloma–osteoclast cells are added to the model to describe the populations inside lytic lesions. It transpires that their presence expands the available parameter space for stable equilibrium, thus permitting a detrimental, larger population of osteoclasts and myeloma cells. A possible relapse mechanism for the illness is explored by letting joint cells dissociate. The mathematics then permits the evaluation of the evolution of the cell populations as a function of time during relapse.
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Project description:The overexpression of PIM kinases in hematologic malignancies, including multiple myeloma, make PIM inhibitors an attractive therapeutic strategy for these diseases. Recent preclinical data from our group demonstrated the anti-myeloma effect of the pan-PIM kinase inhibitor PIM447, along with its synergistic effect with standard of care anti-myeloma agents. Based on those previous data, we have evaluated here the in vitro and in vivo activity of the triple combination of PIM447 + pomalidomide + dexamethasone (PIM-Pd). Our results show that this combination exerts a potent anti-myeloma effect in vitro, even in presence of microenvironment cells, and, in vivo, it markedly delays tumor growth and prolongs survival. Mechanism of action studies suggest that the combination PIM-Pd inhibits protein translation processes through the convergent inhibition of mTORC1, which disrupts the function eIF4E, and c-Myc. As a consequence, cell cycle arrest and disruption of metabolic pathways, including glycolysis and lipid biosynthesis, is induced, inhibiting myeloma cell proliferation. Altogether, these data support the potential future clinical development of the triple combination PIM-Pd for the treatment of patients with MM.