RESUMO
Hepatocellular carcinoma (HCC) is the most predominant primary malignancy in the liver. Genotoxic and genetic models have revealed that HCC cells are derived from hepatocytes, but where the critical region for tumor foci emergence is and how this transformation occurs are still unclear. Here, hyperpolyploidization of hepatocytes around the centrilobular (CL) region is demonstrated to be closely linked with the development of HCC cells after diethylnitrosamine treatment. We identify the CL region as a dominant lobule for accumulation of hyperpolyploid hepatocytes and preneoplastic tumor foci formation. We also demonstrate that upregulation of Aurkb plays a critical role in promoting hyperpolyploidization. Increase of AURKB phosphorylation is detected on the midbody during cytokinesis, causing abscission failure and hyperpolyploidization. Pharmacological inhibition of AURKB dramatically reduces nucleus size and tumor foci number surrounding the CL region in diethylnitrosamine-treated liver. Our work reveals an intimate molecular link between pathological hyperpolyploidy of CL hepatocytes and transformation into HCC cells.
Assuntos
Carcinoma Hepatocelular/genética , Transformação Celular Neoplásica/genética , Hepatócitos/metabolismo , Neoplasias Hepáticas/genética , Fígado/metabolismo , Poliploidia , Lesões Pré-Cancerosas/genética , Animais , Carcinoma Hepatocelular/induzido quimicamente , Carcinoma Hepatocelular/metabolismo , Transformação Celular Neoplásica/induzido quimicamente , Transformação Celular Neoplásica/metabolismo , Células Cultivadas , Dietilnitrosamina/toxicidade , Feminino , Hepatócitos/efeitos dos fármacos , Humanos , Fígado/efeitos dos fármacos , Fígado/patologia , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos ICR , Camundongos Endogâmicos NOD , Camundongos Knockout , Camundongos SCID , Microscopia Confocal , Lesões Pré-Cancerosas/induzido quimicamente , Lesões Pré-Cancerosas/metabolismoRESUMO
Eukaryotic mRNAs are 5' end capped with a 7-methylguanosine, which is important for processing and translation of mRNAs. Cap methyltransferase 1 (CMTR1) catalyzes 2'-O-ribose methylation of the first transcribed nucleotide (N1 2'-O-Me) to mask mRNAs from innate immune surveillance by retinoic-acid-inducible gene-I (RIG-I). Nevertheless, whether this modification regulates gene expression for neuronal functions remains unexplored. Here, we find that knockdown of CMTR1 impairs dendrite development independent of secretory cytokines and RIG-I signaling. Using transcriptomic analyses, we identify altered gene expression related to dendrite morphogenesis instead of RIG-I-activated interferon signaling, such as decreased calcium/calmodulin-dependent protein kinase 2α (Camk2α). In line with these molecular changes, dendritic complexity in CMTR1-insufficient neurons is rescued by ectopic expression of CaMK2α but not by inactivation of RIG-I signaling. We further generate brain-specific CMTR1-knockout mice to validate these findings in vivo. Our study reveals the indispensable role of CMTR1-catalyzed N1 2'-O-Me in gene regulation for brain development.