RESUMO
BACKGROUND & AIMS: Hepatocellular carcinoma is composed of a subset of cells with enhanced tumorigenicity and chemoresistance that are called cancer stem (or stem-like) cells. We explored the role of chromodomain-helicase-DNA-binding protein 4, which is encoded by the CHD4 gene and is known to epigenetically control gene regulation and DNA damage responses in EpCAM(+) liver cancer stem cells. METHODS: Gene and protein expression profiles were determined by microarray and immunohistochemistry in 245 and 144 hepatocellular carcinoma patients, respectively. The relationship between gene/protein expression and prognosis was examined. The functional role of CHD4 was evaluated in primary hepatocellular carcinoma cells and in cell lines in vitro and in vivo. RESULTS: CHD4 was abundantly expressed in EpCAM(+) hepatocellular carcinoma with expression of hepatic stem cell markers and poor prognosis in two independent cohorts. In cell lines, CHD4 knockdown increased chemosensitivity and CHD4 overexpression induced epirubicin chemoresistance. To inhibit the functions of CHD4 that are mediated through histone deacetylase and poly (ADP-ribose) polymerase, we evaluated the effect of the histone deacetylase inhibitor suberohydroxamic acid and the poly (ADP-ribose) polymerase inhibitor AG-014699. Treatment with either suberohydroxamic acid or AG-014699 reduced the number of EpCAM(+) liver cancer stem cells in vitro, and suberohydroxamic acid and AG-014699 in combination successfully inhibited tumor growth in a mouse xenograft model. CONCLUSIONS: CHD4 plays a pivotal role in chemoresistance and the maintenance of stemness in liver cancer stem cells and is therefore a good target for the eradication of hepatocellular carcinoma.
Assuntos
Autoantígenos/genética , Carcinoma Hepatocelular/genética , Molécula de Adesão da Célula Epitelial/genética , Regulação Neoplásica da Expressão Gênica , Neoplasias Hepáticas/genética , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/genética , Células-Tronco Neoplásicas/metabolismo , RNA Neoplásico/genética , Animais , Autoantígenos/biossíntese , Biomarcadores Tumorais/biossíntese , Biomarcadores Tumorais/genética , Western Blotting , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Linhagem Celular Tumoral , Proliferação de Células , Montagem e Desmontagem da Cromatina , Molécula de Adesão da Célula Epitelial/biossíntese , Hepatectomia , Humanos , Imuno-Histoquímica , Fígado/metabolismo , Fígado/patologia , Fígado/cirurgia , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas Experimentais/genética , Neoplasias Hepáticas Experimentais/metabolismo , Neoplasias Hepáticas Experimentais/patologia , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/biossíntese , Camundongos , Camundongos Endogâmicos NOD , Células-Tronco Neoplásicas/patologia , Prognóstico , Estudos Retrospectivos , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Colorectal cancer (CRC) has ranked first in terms of incidence in Taiwan. Surgical resection combined with chemo-, radio-, or targeted-therapies are the main treatments for CRC patients in current clinical practice. However, many CRC patients still respond poorly to these treatments, leading to tumor recurrence and an unacceptably high incidence of metastasis and death. Therefore, appropriate diagnosis, treatment, and drug selection are pressing issues in clinical practice. The Mi-2/nucleosome remodeling and deacetylase complex is an important epigenetic regulator of chromatin structure and gene expression. An important component of this complex is chromodomain-helicase-DNA-binding protein 4 (CHD4), which is involved in DNA repair after injury. Recent studies have indicated that CHD4 has oncogenic functions that inhibit multiple tumor suppressor genes through epigenetic regulation. However, the role of CHD4 in CRC has not yet been well investigated. In this study, we compared CHD4 expression in CRC patients from The Cancer Genome Atlas database. We found higher levels of CHD4 expression in CRC patients. In a series of in vitro experiments, we found that CHD4 affected cell motility and drug sensitivity in CRC cells. In animal models, the depletion of CHD4 affected CRC tumor growth, and the combination of a histone deacetylase 1 (HDAC1) inhibitor and platinum drugs inhibited CHD4 expression and increased the cytotoxicity of platinum drugs. Moreover, CHD4 expression was also a prognostic biomarker in CRC patients. Based on the above results, we believe that CHD4 expression is a viable biomarker for predicting metastasis CRC patients, and it has the potential to become a target for drug development.
Assuntos
Neoplasias Colorretais/genética , DNA de Neoplasias/genética , Epigênese Genética/genética , Regulação Neoplásica da Expressão Gênica , Histona Desacetilase 1/genética , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/genética , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Reparo do DNA , Histona Desacetilase 1/biossíntese , Humanos , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/biossíntese , Oncogenes/genéticaRESUMO
CHD5 is frequently deleted in neuroblastoma and is a tumor suppressor gene. However, little is known about the role of CHD5 other than it is homologous to chromatin remodeling ATPases. We found CHD5 mRNA was restricted to the brain; by contrast, most remodeling ATPases were broadly expressed. CHD5 protein isolated from mouse brain was associated with HDAC2, p66ß, MTA3 and RbAp46 in a megadalton complex. CHD5 protein was detected in several rat brain regions and appeared to be enriched in neurons. CHD5 protein was predominantly nuclear in primary rat neurons and brain sections. Microarray analysis revealed genes that were upregulated and downregulated when CHD5 was depleted from primary neurons. CHD5 depletion altered expression of neuronal genes, transcription factors, and brain-specific subunits of the SWI/SNF remodeling enzyme. Expression of gene sets linked to aging and Alzheimer's disease were strongly altered by CHD5 depletion from primary neurons. Chromatin immunoprecipitation revealed CHD5 bound to these genes, suggesting the regulation was direct. Together, these results indicate that CHD5 protein is found in a NuRD-like multi-protein complex. CHD5 expression is restricted to the brain, unlike the closely related family members CHD3 and CHD4. CHD5 regulates expression of neuronal genes, cell cycle genes and remodeling genes. CHD5 is linked to regulation of genes implicated in aging and Alzheimer's disease.