RESUMO
Glioblastoma is a severe type of brain tumor with a poor prognosis and few therapy options. Temozolomide (TMZ) is one of these options, however, with limited success, and failure is mainly due to tumor resistance. In this work, genome-wide CRISPR-Cas9 lentiviral screen libraries for gene knockout or activation were transduced in the human glioblastoma cell line, aiming to identify genes that modulate TMZ resistance. The sgRNAs enriched in both libraries in surviving cells after TMZ treatment were identified by next-generation sequencing (NGS). Pathway analyses of gene candidates on knockout screening revealed several enriched pathways, including the mismatch repair and the Sonic Hedgehog pathways. Silencing three genes ranked on the top 10 list (MSH2, PTCH2, and CLCA2) confirm cell protection from TMZ-induced death. In addition, a CRISPR activation library revealed that NRF2 and Wnt pathways are involved in TMZ resistance. Consistently, overexpression of FZD6, CTNNB1, or NRF2 genes significantly increased cell survival upon TMZ treatment. Moreover, NRF2 and related genes detected in this screen presented a robust negative correlation with glioblastoma patient survival rates. Finally, several gene candidates from knockout or activation screening are targetable by inhibitors or small molecules, and some of them have already been used in the clinic.
Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas/genética , Resistencia a Medicamentos Antineoplásicos/genética , Temozolomida/farmacologia , Neoplasias Encefálicas/tratamento farmacológico , Neoplasias Encefálicas/genética , Linhagem Celular Tumoral , Sobrevivência Celular/genética , Regulação Neoplásica da Expressão Gênica/genética , Estudo de Associação Genômica Ampla/métodos , Glioblastoma/tratamento farmacológico , Glioblastoma/genética , Proteínas Hedgehog/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Humanos , Bibliotecas de Moléculas Pequenas/farmacologiaRESUMO
The cell cycle involves a network of proteins that modulate the sequence and timing of proliferation events. Unregulated proliferation is the most fundamental hallmark of cancer; thus, changes in cell cycle control are at the heart of malignant transformation processes. Several cellular processes can interfere with the cell cycle, including autophagy, the catabolic pathway involved in degradation of intracellular constituents in lysosomes. According to the mechanism used to deliver cargo to the lysosome, autophagy can be classified as macroautophagy (MA), microautophagy (MI), or chaperone-mediated autophagy (CMA). Distinct from other autophagy types, CMA substrates are selectively recognized by a cytosolic chaperone, one-by-one, and then addressed for degradation in lysosomes. The function of MA in cell cycle control, and its influence in cancer progression, are already well-established. However, regulation of the cell cycle by CMA, in the context of tumorigenesis, has not been fully addressed. This review aims to present and debate the molecular mechanisms by which CMA can interfere in the cell cycle, in the context of cancer. Thus, cell cycle modulators, such as MYC, hypoxia-inducible factor-1 subunit alpha (HIF-1α), and checkpoint kinase 1 (CHK1), regulated by CMA activity will be discussed. Finally, the review will focus on how CMA dysfunction may impact the cell cycle, and as consequence promote tumorigenesis.
Assuntos
Carcinogênese/genética , Pontos de Checagem do Ciclo Celular/genética , Autofagia Mediada por Chaperonas/genética , Regulação Neoplásica da Expressão Gênica , Chaperonas Moleculares/genética , Neoplasias/genética , Autofagia/genética , Carcinogênese/metabolismo , Carcinogênese/patologia , Quinase 1 do Ponto de Checagem/genética , Quinase 1 do Ponto de Checagem/metabolismo , Progressão da Doença , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Lisossomos/metabolismo , Chaperonas Moleculares/metabolismo , Neoplasias/metabolismo , Neoplasias/patologia , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Proteólise , Proteínas Proto-Oncogênicas c-myc/genética , Proteínas Proto-Oncogênicas c-myc/metabolismo , Transdução de SinaisRESUMO
The cell cycle involves a network of proteins that modulate the sequence and timing of proliferation events. Unregulated proliferation is the most fundamental hallmark of cancer; thus, changes in cell cycle control are at the heart of malignant transformation processes. Several cellular processes can interfere with the cell cycle, including autophagy, the catabolic pathway involved in degradation of intracellular constituents in lysosomes. According to the mechanism used to deliver cargo to the lysosome, autophagy can be classified as macroautophagy (MA), microautophagy (MI), or chaperone-mediated autophagy (CMA). Distinct from other autophagy types, CMA substrates are selectively recognized by a cytosolic chaperone, one-by-one, and then addressed for degradation in lysosomes. The function of MA in cell cycle control, and its influence in cancer progression, are already well-established. However, regulation of the cell cycle by CMA, in the context of tumorigenesis, has not been fully addressed. This review aims to present and debate the molecular mechanisms by which CMA can interfere in the cell cycle, in the context of cancer. Thus, cell cycle modulators, such as MYC, hypoxia-inducible factor-1 subunit alpha (HIF-1α), and checkpoint kinase 1 (CHK1), regulated by CMA activity will be discussed. Finally, the review will focus on how CMA dysfunction may impact the cell cycle, and as consequence promote tumorigenesis
