RESUMEN

Chemotherapy is the first-line treatment for human retinoblastoma (RB), but the occurrence of drug resistance greatly limited its efficacy in practice. RING-finger protein 6 (RNF6) is an E3 ubiquitin ligase that is aberrantly upregulated in a range of cancers and plays important roles in cancer progression. However, the role of RNF6 in RB is largely unknown. In this study, we investigated the role of RNF6 in RB drug resistance. Two carboplatin-resistant RB cells, Y-79/CR and SO-Rb50/CR, were generated based on Y-79 and SO-Rb50 cells. RT-PCR and western blot analyses showed that RNF6 expression on both mRNA and protein levels was significantly increased in Y-79/CR and SO-Rb50/CR cells comparing to their parental cells. Knockdown of RNF6 using siRNA in Y-79/CR and SO-Rb50/CR cells resulted in cells sensitive to carboplatin on a RNF6 siRNA dose dependent manner. Similarly, RNF6 overexpression in parental Y-79 and SO-Rb50 cells could help cells gain resistance to carboplatin on a RNF6 expression dependent manner. Signaling pathway analyses revealed that JAK2/STAT3 pathway was involved in the RNF6-induced carboplatin resistance in RB cells. We further revealed that RNF6 expression in both Y-79 and SO-Rb50 cells could render cells resistant to multiple anti-cancer drugs including carboplatin, vincristine and etoposide, an implication of RNF6 as a biomarker for RB drug resistance. Taken together, our study has revealed that RNF6 is upregulated in drug-resistant RB cells and RNF6 promotes drug resistance through JAK2/STAT3 signaling pathway. The importance of RNF6 in RB cells drug resistance may represent this protein as a potential biomarker and treatment target for drug resistance in RB.

Asunto(s)

Neoplasias de la Retina , Retinoblastoma , Línea Celular Tumoral , Proteínas de Unión al ADN/genética , Resistencia a Medicamentos , Humanos , Janus Quinasa 2 , Neoplasias de la Retina/tratamiento farmacológico , Neoplasias de la Retina/genética , Retinoblastoma/tratamiento farmacológico , Retinoblastoma/genética , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/metabolismo , Transducción de Señal

RESUMEN

Ring finger protein 6 (RNF6), a member of E3 ubiquitin ligases, plays a potential role as a tumour promoter in numerous carcinomas. However, the role and expression of RNF6 in breast cancer (BC) remains to be elucidated. The present study showed that RNF6 upregulation was detected in BC tissues and was associated with short survival in patients with BC. Multivariate analysis also revealed that RNF6 overexpression is an independent predictor for poor outcome of patients with BC. Furthermore, migration and metastasis assay indicated that RNF6 silencing significantly inhibited the invasion and migration of BC cells in vivo and in vitro, and RNF6 suppression decreased YES-associated protein (YAP) expression. RNF6 promoted the metastatic ability of BC cells via YAP. Mechanistically, RNF6 interacts with mammalian STE20-like protein kinase 1 (MST1), a key factor that regulates YAP, and promoted its ubiquitination and degradation. Additionally, RNF6 regulated YAP signalling by promoting ubiquitination and degradation of MST1 in BC. Taken together, these data may highlight a role of RNF6 in BC, which could serve as a valuable prognostic indicator and potential therapeutic target for patients with BC.

RESUMEN

BACKGROUND: Traumatic brain injury (TBI) has ranked as one of the leading causes of disability and death in the world. The neuroinflammation mediated by signal transducer and activator of transcription 3 (STAT3) signaling during the progression of TBI leads to long-term neurodegeneration. Ring finger protein 6 (RNF-6) is an E3 ubiquitin ligase and can regulate the activity of STAT3 signaling pathway by targeting its inhibitors. However, the mechanism underlying this process in TBI remains poorly understood. METHODS: In this research, cortical impact injury was used to construct the TBI rat model. Western blot assay was performed to evaluate the protein levels of RNF6, Src homology 2 domain-containing protein tyrosine phosphatase 1 (SHP-1), and STAT3/pSTAT3. QRT-PCR assay was performed to assess the RNA levels of RNF6 and other cytokines. The neural function of TBI rats was estimated by modified Neurological Severity Scores test. RESULTS: The expression of RNF-6 was up-regulated in the brain tissues of TBI rats. Down-regulation of RNF6 alleviated the symptoms and improved the neural recovery postinjury in TBI rats. Inhibition of RNF6 suppressed the cerebral inflammation by up-regulating the protein level of SHP-1 and down-regulating the phosphorylation level of STAT3. CONCLUSION: Inhibition of RNF6 alleviated TBI by suppressing the STAT3 signaling in TBI rats.

Asunto(s)

Lesiones Traumáticas del Encéfalo , Factor de Transcripción STAT3 , Animales , Lesiones Traumáticas del Encéfalo/tratamiento farmacológico , Inflamación , Fosforilación , Ratas , Factor de Transcripción STAT3/metabolismo , Transducción de Señal

RESUMEN

Acute myeloid leukemia (AML) is a heterogeneous disease characterized by the accu-mulation of immature myeloid progenitor cells in the bone marrow,compromising of normal hematopoi-esis and ultimately resulting in bone marrow failure. Chemotherapy is the mainstay treatment for all AML patients,however,drug resistance and clinical relapse limits its efficacy.The 5-year survival rate of AML patients is only 26.6%.Survival rates are even lower among patients ages 65 to 74 years (5.3%)and 75 years or older(1.6%).Therefore,exploring novel therapeutic agents is urgent for improving the outcome of patients with AML. Saponins are amphipathic glycosides found in traditional Chinese medicines. In the present study, we isolated a panel of saponins from Paris forrestii (Takht.) H. Li, a unique plant found in Tibet and Yunnan provinces, China. By examining their activities in suppressing acute myeloid leukemia cell proliferation, total saponins from Paris forrestii (TSPf) displayed more potent activity than individual ones.TSPf induced more than 40% AML cell apoptosis within 24 h and decreased the viability of all leukemia cell lines. TSPf-induced apoptosis was confirmed by both Annexin V staining and caspase-3 activation.TSPf downregulated pro-survival proteins Mcl-1,Bcl-xL and Bcl-2,but upreg-ulated the expression of tumor suppressor proteins p53,p27,Bax and Beclin 1.The AKT/mTOR signaling pathway is frequently over activated in various AML cells,and TSPf was found to suppress the activa-tion of both AKT and mTOR,but had no effects on their total protein expression.This was further con-firmed by the inactivation of 4EBP-1 and p70S6K,two typical downstream signal molecules in the AKT/mTOR pathway. More specifically, TSPf-inactivated AKT/mTOR signaling was found to be associated with downregulated RNF6, a recently identified oncogene in AML. RNF6 activated AKT/mTOR, and consistently, knockdown of RNF6 led to inactivation of the AKT/mTOR pathway. Furthermore, TSPf suppressed the growth of AML xenografts in nude mice models. Oral administration of 100 mg·kg-1 body weight almost fully suppressed tumor growth within 14 d, without gross toxicity. This study thus demonstrated that TSPf displays potent anti-AML activity by suppressing the RNF6/AKT/mTOR pathway. Given its low toxicity,TSPf could be developed for the treatment of AML.

RESUMEN

Ring finger protein 6 (RNF6) is a key oncogene in both prostate cancer and leukemia, but its role is elusive in breast cancer. In the present study, we found that RNF6 was overexpressed in more than 70% of breast cancer tissues and it was associated with overall survival. RNF6 increased breast cancer cell proliferation, migration and reduced cell sensitivity to doxorubicin. Further studies showed that RNF6 was closely associated with increased expression of estrogen receptor, a critical factor in the development of breast cancers. RNF6 was found to induce ERα expression and increased its stability. In doxorubicin-resistant breast cancer cells, RNF6 was found to be elevated in association with increased ERα and anti-apoptotic Bcl-xL, but not pro-apoptotic Bim-1. In consistence with this finding, overexpression of ERα led to increased Bcl-xL but had no effects on Bim-1. Therefore, this study demonstrated that there exists an RNF6/ERα/Bcl-xL axle in breast cancer which promotes cancer cell proliferation and survival. Targeting the RNF6/ERα/Bcl-xL axle could be a promising strategy in the treatment of breast cancer.

Asunto(s)

Biomarcadores de Tumor/metabolismo , Neoplasias de la Mama/patología , Carcinoma Ductal de Mama/secundario , Proliferación Celular , Proteínas de Unión al ADN/metabolismo , Receptor alfa de Estrógeno/metabolismo , Proteína bcl-X/metabolismo , Apoptosis , Biomarcadores de Tumor/genética , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/metabolismo , Estudios de Casos y Controles , Proteínas de Unión al ADN/genética , Receptor alfa de Estrógeno/genética , Femenino , Estudios de Seguimiento , Humanos , Metástasis Linfática , Persona de Mediana Edad , Clasificación del Tumor , Invasividad Neoplásica , Estadificación de Neoplasias , Pronóstico , Tasa de Supervivencia , Células Tumorales Cultivadas , Proteína bcl-X/genética

RESUMEN

Objective To construct an eukaryotic expression vetor of ring finger protein 6 (RNF6)and to investigate its ubiqu-itylation on insulin receptor substrate-1(IRS-1).Methods Human RNF6 coding sequence was amplified by polymerase chain reac-tion (PCR)method with human cDNA as template.The pcDNA3.1-CHA-RNF6 was constructed with routine molecular methods and transfected into hepatocarcinoma cell HepG2.Relative quantification of IRS-1 mRNA was preformed by real-time reverse tran-scription PCR.Western blot was applied to detect the expression levels of IRS-1.Results 48 h after the plasmid carring RNF6 gene transfected HepG2 cells,the mRNA level of ISR-1 gene reduced to 69% of control group.The expression of IRS-1 was markedly lower than control group (P <0.01).Conclusion The expression of IRS-1 is markedly down-regulated in HepG2 and enhancement of the ubiquitylation level of IRS-1 contribute to the disorder in insulin signal transferring.