ABSTRACT
@#Objective To investigate the expression of methyltransferase like-3(METTL3)in esophageal cancer tissues and its effects on the proliferation,migration,apoptosis and glutamine metabolism of cells.Methods The expression of METTL3 in esophageal cancer and paraneoplastic tissues was detected by qRT-PCR,Western blot and Immunohistochemistry. The effects of METTL3 inhibitor STM2457 on cell proliferation and migration of human esophageal squamous carcinoma cell lines Eca109 and KYSE150 were detected by CCK8,cloning assay,scratch test and Transwell assay. The effects on cell cycle and cell apoptosis were measured by flow cytometry and TUNEL experiment. TMT/iTRAQ quantitative proteomics experiment was used to identify the effects on downstream related signaling pathways. Glutamine assay,glutamate assay and Western blot were used to analyze the effect on glutamine metabolism in esophageal cancer cells.Results METTL3 gene expression was significantly upregulated in esophageal cancer tissues(t = 5. 024,P < 0. 000 1). STM2457 inhibited METTL3 expression in Eca109 and KYSE150 cells,significantly inhibited the cell proliferation and migration,blocked the cell cycle in G0/G1 phase,increased the cell apoptosis,decreased the glutamine uptake and glutamate production,and down-regulated the expression of glutamine-related proteins alanine-serine-cysteine transporter 2(ASCT2),glutaminase(GLS)and glutamate dehydrogenase 1(GLUD1). The glutamine uptake and glutamate production in Eca109 and KYSE150 cells decreased significantly after METTL3 knockdown(glutamine uptake:t = 24. 52-41. 01,each P < 0. 01;glutamate production:t = 8. 431-11. 83,each P < 0. 01);After METTL3 overexpression,the glutamine uptake and glutamate production in Eca109 and KYSE150 cells increased significantly(glutamine uptake:t = 5. 803 and 56. 13,respectively,each P < 0. 01;glutamate production:t = 11. 06 and 4. 695,respectively,each P < 0. 01). After METTL3 knockdown,the expression levels of glutamine metabolism related proteins ASCT2,GLS and GLUD1 in Eca109 and KYSE150 cells were significantly down-regulated,while after METTL3 overexpression,the expression levels of ASCT2,GLS and GLUD1 were significantly up-regulated.Conclusion METTL3 is highly expressed in esophageal cancer and may promote cell proliferation by mediating glutamine metabolism in esophageal cancer cells.
ABSTRACT
In non-small cell lung cancer(NSCLC),the heterogeneity promotes drug resistance,and the restricted expression of programmed death-ligand 1(PD-L1)limits the immunotherapy benefits.Based on the mechanisms related to translation regulation and the association with PD-L1 of methyltransferase-like 3(METTL3),the novel small-molecule inhibitor STM2457 is assumed to be useful for the treat-ment of NSCLC.We evaluated the efficacy of STM2457 in vivo and in vitro and confirmed the effects of its inhibition on disease progression.Next,we explored the effect of STM2457 on METTL3 and revealed its effects on the inhibition of catalytic activity and upregulation of METTL3 protein expression.Importantly,we described the genome-wide characteristics of multiple omics data ac-quired from RNA sequencing,ribosome profiling,and methylated RNA immunoprecipitation sequencing data under STM2457 treatment or METTL3 knockout.We also constructed a model for the regulation of the translation of METTL3 and PD-L1.Finally,we found PD-Ll upregulation by STM2457 in vivo and in vitro.In conclusion,STM2457 is a potential novel suppressor based on its inhibitory effect on tumor progression and may be able to overcome the heterogeneity based on its impact on the translatome.Furthermore,it can improve the immunotherapy outcomes based on PD-L1 upregulation in NSCLC.