RESUMO
Resistance to glucocorticoids (GC), the common agents for remission induction in pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL), poses a significant therapeutic hurdle. Therefore, dissecting the mechanisms shaping GC resistance could lead to new treatment modalities. Here, we showed that CD9- BCP-ALL cells were preferentially resistant to prednisone and dexamethasone over other standard cytotoxic agents. Concordantly, we identified significantly more poor responders to the prednisone prephase among BCP-ALL patients with a CD9- phenotype, especially for those with adverse presenting features including older age, higher white cell count and BCR-ABL1. Furthermore, gain- and loss-offunction experiments dictated a definitive functional linkage between CD9 expression and GC susceptibility, as demonstrated by the reversal and acquisition of relative GC resistance in CD9low and CD9high BCP-ALL cells, respectively. Despite physical binding to the GC receptor NR3C1, CD9 did not alter its expression, phosphorylation or nuclear translocation but potentiated the induction of GC-responsive genes in GC-resistant cells. Importantly, the MEK inhibitor trametinib exhibited higher synergy with GC against CD9- than CD9+ lymphoblasts to reverse drug resistance in vitro and in vivo. Collectively, our results elucidate a previously unrecognized regulatory function of CD9 in GC sensitivity, and inform new strategies for management of children with resistant BCP-ALL.
Assuntos
Resistencia a Medicamentos Antineoplásicos , Glucocorticoides , Leucemia-Linfoma Linfoblástico de Células Precursoras B , Tetraspanina 29 , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras B/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras B/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologia , Tetraspanina 29/metabolismo , Tetraspanina 29/genética , Glucocorticoides/farmacologia , Glucocorticoides/uso terapêutico , Resistencia a Medicamentos Antineoplásicos/genética , Criança , Animais , Camundongos , Receptores de Glucocorticoides/metabolismo , Receptores de Glucocorticoides/genética , Linhagem Celular Tumoral , Masculino , Feminino , Pré-Escolar , Dexametasona/farmacologiaRESUMO
The microenvironment plays a vital role in tumor progression, and hypoxia is a typical microenvironment feature in nearly all solid tumors. In this study, we focused on elucidating the effect of canagliflozin (CANA), a new class of antidiabetic agents, on hepatocarcinoma (HCC) tumorigenesis under hypoxia, and demonstrated that CANA could significantly inhibit hypoxia-induced metastasis, angiogenesis, and metabolic reprogramming in HCC. At the molecular level, this was accompanied by a reduction in VEGF expression level, as well as a reduction in the epithelial-to-mesenchymal transition (EMT)-related proteins and glycolysis-related proteins. Next, we focused our study particularly on the modulation of HIF-1α by CANA, which revealed that CANA decreased HIF-1α protein level by inhibiting its synthesis without affecting its proteasomal degradation. Furthermore, the AKT/mTOR pathway, which plays an important role in HIF-1α transcription and translation, was also inhibited by CANA. Thus, it can be concluded that CANA decreased metastasis, angiogenesis, and metabolic reprogramming in HCC by inhibiting HIF-1α protein accumulation, probably by targeting the AKT/mTOR pathway. Based on our results, we propose that CANA should be evaluated as a new treatment modality for liver cancer.
Assuntos
Canagliflozina/farmacologia , Carcinoma Hepatocelular/tratamento farmacológico , Glicólise/efeitos dos fármacos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Neoplasias Hepáticas/tratamento farmacológico , Neovascularização Patológica/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Animais , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Hipóxia Celular/efeitos dos fármacos , Hipóxia Celular/genética , Células Hep G2 , Células Endoteliais da Veia Umbilical Humana , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Camundongos SCID , Metástase Neoplásica , Neovascularização Patológica/genética , Neovascularização Patológica/metabolismo , Neovascularização Patológica/patologia , Proteínas Proto-Oncogênicas c-akt/genética , Serina-Treonina Quinases TOR/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The aberrant expression of RNA-binding proteins (RBPs) plays important roles in the occurrence and progression of cancer. MBNL2 is a member of the RNA binding protein MBNL family that is widely expressed in mammalian cells. We report here that MBNL2 is downregulated in breast, lung and liver cancer tissues, the promoter methylation levels of MBNL2 are higher in cancer tissues than normal tissues. The enrichment analysis of MBNL2 correlated genes indicates the potential function of MBNL2 on cancer progression. MBNL2 regulates cancer cell migration and invasion by modulating PI3K/AKT-mediated epithelial-mesenchymal transition. PI3K/AKT inhibitor overcomes the promotive effect of shMBNL2 on metastasis. The expression of MBNL2 is directly targeted by miR-182. miR-182 is upregulated in breast, lung and liver cancers and has good potential for cancer diagnosis. miR-182 promotes cancer cell migration and invasion by inhibiting the expression of MBNL2. Re-introduction of exogenous MBNL2 reverses the promotive effect of miR-182 on metastasis. Collectively, these findings suggest that MBNL2 plays a tumor suppressive function through miR-182-MBNL2-AKT-EMT signaling pathways.
RESUMO
RNA-binding proteins are frequently dysregulated in human cancer and able to modulate tumor cell proliferation as well as tumor metastasis through post-transcriptional regulation on target genes. Abnormal DNA damage response and repair mechanism are closely related to genome instability and cell transformation. Here, we explore the function of the RNA-binding protein muscleblind-like splicing regulator 2 (MBNL2) on tumor cell proliferation and DNA damage response. Transcriptome and gene expression analysis show that the PI3K/AKT pathway is enriched in MBNL2-depleted cells, and the expression of cyclin-dependent kinase inhibitor 1A (p21CDKN1A) is significantly affected after MBNL2 depletion. MBNL2 modulates the mRNA and protein levels of p21, which is independent of its canonical transcription factor p53. Moreover, depletion of MBNL2 increases the phosphorylation levels of checkpoint kinase 1 (Chk1) serine 345 (S345) and DNA damage response, and the effect of MBNL2 on DNA damage response is p21-dependent. MBNL2 would further alter tumor cell fate after DNA damage, MBNL2 knockdown inhibiting DNA damage repair and DNA damage-induced senescence, but promoting DNA damage-induced apoptosis.
Assuntos
Inibidor de Quinase Dependente de Ciclina p21/genética , Dano ao DNA , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica , Proteínas de Ligação a RNA/genética , Apoptose/genética , Proliferação de Células/genética , Quinase 1 do Ponto de Checagem/genética , Quinase 1 do Ponto de Checagem/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Células HCT116 , Células HeLa , Humanos , Fosforilação , Proteínas de Ligação a RNA/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
CELF6, a member of the CELF family of RNA-binding proteins, regulates muscle-specific alternative splicing and contributes to the pathogenesis of myotonic dystrophy (DM), however the role of CELF6 in cancer cell proliferation is less appreciated. Here, we show that the expression of CELF6 is cell cycle regulated. The cell cycle-dependent expression of CELF6 is mediated through the ubiquitin-proteasome pathway, SCF-ß-TrCP recognizes a nonphospho motif in CELF6 and regulates its proteasomal degradation. Overexpression or depletion of CELF6 modulates p21 gene expression. CELF6 binds to the 3'UTR of p21 transcript and increases its mRNA stability. Depletion of CELF6 promotes cell cycle progression, cell proliferation and colony formation whereas overexpression of CELF6 induces G1 phase arrest. The effect of CELF6 on cell proliferation is p53 and/or p21 dependent. Collectively, these data demonstrate that CELF6 might be a potential tumor suppressor, CELF6 regulates cell proliferation and cell cycle progression via modulating p21 stability.
Assuntos
Proteínas CELF/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Proteínas CELF/biossíntese , Proteínas CELF/genética , Ciclo Celular/fisiologia , Proliferação de Células/fisiologia , Inibidor de Quinase Dependente de Ciclina p21/genética , Técnicas de Inativação de Genes , Células HCT116 , Células HEK293 , Humanos , Complexo de Endopeptidases do Proteassoma/metabolismo , Estabilidade Proteica , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Ligases SKP Culina F-Box/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina/metabolismoRESUMO
Lipoic acid synthase (LipA) plays a role in lipoic acid synthesis and potentially affects the levels of acetyl-CoA, the critical precursor of tricarboxylic acid (TCA) cycle. Considering the potential effect of LipA on TCA cycle, whether the enzyme is involved in the growth and aflatoxin B1 (AFB1) biosynthesis, the significant events in Aspergillus flavus is yet known. The study was designed to explore the role of lipA gene in A. flavus, including growth rate, conidiation, sclerotia formation, and biosynthesis of AFB1. LipA coding lipoic acid synthetase was knocked out using homologous recombination. The role of lipA gene in A. flavus morphogenesis (including colony size, conidiation, and sclerotia formation) was explored on various media, and the bio-function of lipA gene in the biosynthesis of AFB1 was analyzed by thin layer chromatography analysis. The growth was suppressed in â³lipA. The formation of conidia and sclerotia was also reduced when lipA gene was deleted. Moreover, AFB1 was down-regulated in ΔlipA compared with WT controls. LipA plays a role in the development of A. flavus and AFB1 biosynthesis, contributing to the full understanding of the lipA bio-function in A. flavus.
Assuntos
Aspergillus/genética , Proteínas Fúngicas/genética , Sulfurtransferases/genética , Aspergillus/enzimologia , Aspergillus/crescimento & desenvolvimento , Proteínas Fúngicas/metabolismo , Mutação , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/metabolismo , Sulfurtransferases/metabolismoRESUMO
Aspergillus flavus produces mycotoxins especially aflatoxin B1 and infects crops worldwide. As a PHD transcription factor, there is no report on the role of Rum1 in the virulence of Aspergillus spp. yet. This study explored the biological function of Rum1 in A. flavus through the construction of rum1 deletion mutants and rum1 complementation strains with the method of homologous recombination. It was found, in the study, that Rum1 negatively regulates conidiation through abaA and brlA, positively regulates sclerotia formation through nsdC, nsdD, and sclR, triggers aflatoxin biological synthesis, and enhances the activity of amylase. Our findings suggested that Rum1 plays a major role in the growth of mycelia, conidia, and sclerotia production along with aflatoxin biosynthesis in A. flavus.