RESUMO
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMO
Inhibitors against poly (ADP-ribose) polymerase (PARP) are promising targeted agents currently used to treat BRCA-mutant ovarian cancer and are in clinical trials for other cancer types, including BRCA-mutant breast cancer. To enhance the clinical response to PARP inhibitors (PARPis), understanding the mechanisms underlying PARPi sensitivity is urgently needed. Here, we show enhancer of zeste homolog 2 (EZH2), an enzyme that catalyzes H3 lysine trimethylation and associates with oncogenic function, contributes to PARPi sensitivity in breast cancer cells. Mechanistically, upon oxidative stress or alkylating DNA damage, PARP1 interacts with and attaches poly-ADP-ribose (PAR) chains to EZH2. PARylation of EZH2 by PARP1 then induces PRC2 complex dissociation and EZH2 downregulation, which in turn reduces EZH2-mediated H3 trimethylation. In contrast, inhibition of PARP by PARPi attenuates alkylating DNA damage-induced EZH2 downregulation, thereby promoting EZH2-mediated gene silencing and cancer stem cell property compared with PARPi-untreated cells. Moreover, the addition of an EZH2 inhibitor sensitizes the BRCA-mutant breast cells to PARPi. Thus, these results may provide a rationale for combining PARP and EZH2 inhibition as a therapeutic strategy for BRCA-mutated breast and ovarian cancers.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Resistencia a Medicamentos Antineoplásicos , Proteína Potenciadora do Homólogo 2 de Zeste/metabolismo , Neoplasias Ovarianas/tratamento farmacológico , Poli(ADP-Ribose) Polimerase-1/metabolismo , Inibidores de Poli(ADP-Ribose) Polimerases/farmacologia , ADP-Ribosilação/efeitos dos fármacos , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Dano ao DNA , Regulação para Baixo , Proteína Potenciadora do Homólogo 2 de Zeste/antagonistas & inibidores , Proteína Potenciadora do Homólogo 2 de Zeste/genética , Feminino , Inativação Gênica , Humanos , Camundongos , Camundongos Nus , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Poli(ADP-Ribose) Polimerase-1/antagonistas & inibidores , Inibidores de Poli(ADP-Ribose) Polimerases/uso terapêutico , RNA Interferente Pequeno/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The Yes-associated protein (YAP) is an effector that transduces the output of the Hippo pathway to transcriptional modulation. Considering the role of YAP in cancers, this protein has emerged as a key node in malignancy development. In this study, we determined that Aurora A kinase acts as a positive regulator for YAP-mediated transcriptional machinery. Specifically, YAP associates with Aurora A predominantly in the nucleus. Activation of Aurora A can impinge on YAP activity through direct phosphorylation. Moreover, aberrant expression of YAP and Aurora A signaling is highly correlated with triple-negative breast cancer (TNBC). We herein provide evidence to establish the functional relevance of this newly discovered regulatory axis in TNBC.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Aurora Quinase A/metabolismo , Biomarcadores Tumorais/metabolismo , Proliferação de Células , Fosfoproteínas/metabolismo , Neoplasias de Mama Triplo Negativas/metabolismo , Neoplasias de Mama Triplo Negativas/patologia , Animais , Apoptose , Humanos , Técnicas Imunoenzimáticas , Camundongos , Células NIH 3T3 , Fosforilação , Transdução de Sinais , Fatores de Transcrição , Proteínas de Sinalização YAPRESUMO
To investigate the mechanisms underlying our recent paradoxical finding that mitotically incapacitated and genomically unstable polyploid giant cancer cells (PGCCs) are capable of tumor initiation, we labeled ovarian cancer cells with α-tubulin fused to green fluorescent protein, histone-2B fused to red fluorescent protein and FUCCI (fluorescent ubiquitination cell cycle indicator), and tracked the spatial and time-dependent change in spindle and chromosomal dynamics of PGCCs using live-cell fluorescence time-lapse recording. We found that single-dose (500 nm) treatment with paclitaxel paradoxically initiated endoreplication to form PGCCs after massive cell death. The resulting PGCCs continued self-renewal via endoreplication and further divided by nuclear budding or fragmentation; the small daughter nuclei then acquired cytoplasm, split off from the giant mother cells and acquired competency in mitosis. FUCCI showed that PGCCs divided via truncated endoreplication cell cycle (endocycle or endomitosis). Confocal microscopy showed that PGCCs had pronounced nuclear fragmentation and lacked expression of key mitotic proteins. PGCC-derived daughter cells were capable of long-term proliferation and acquired numerous new genome/chromosome alterations demonstrated by spectral karyotyping. These data prompt us to conceptualize a giant cell cycle composed of four distinct but overlapping phases, initiation, self-renewal, termination and stability. The giant cell cycle may represent a fundamental cellular mechanism to initiate genomic reorganization to generate new tumor-initiating cells in response to chemotherapy-induced stress and contributes to disease relapse.
RESUMO
Tanshinone IIA (Tan IIA), a constituent of the traditional medicinal plant Salvia miltiorrhiza BUNGE, has been reported to possess anticancer activity through induction of apoptosis in many cancer cells. Surprisingly, the present study finds that Tan IIA simultaneously causes apoptosis and necroptosis in human hepatocellular carcinoma HepG2 cells. We further find that apoptosis can be converted to necroptosis by pan-caspase inhibitor Z-VAD-fmk, and the two death modes can be blocked by necroptotic inhibitor necrostatin-1. The underlying mechanisms are revealed by analysis of the signaling molecules using western blotting. In control cells, FLICE inhibitory protein in short form (FLIPS) is expressed in relatively high levels and binds to caspase 8 in ripoptosome, which supposedly sustains cell survival. However, in Tan IIA-treated cells, FLIPS is down-regulated and may thus cause homodimer formation of cleaved caspase 8, cleavage of receptor-interacting serine/threonine-protein kinases 1, 3 (RIP1, RIP3), and mixed-lineage kinase domain-like (MLKL), in turn leads to cell apoptosis. In parallel, Tan IIA causes necroptosis by forming a suggested necrosomal complex composed of RIP1/RIP3. Regarding the inhibitors, z-VAD-fmk diminishes the cleaved caspase 8, RIP1, RIP3, and MLKL induced by Tan IIA, and reconstructs the ripoptosome complex, which marks cells moving from apoptosis to necroptosis. Nec-1 recovers the Tan IIA down-regulated FLIPS, consequently causes FLIPS to form heterodimer with caspase 8 and thus block apoptosis. Meanwhile, cleaved forms of RIP1 and RIP3 were observed preventing necroptosis. Intriguingly, the cytotoxicity of tumor necrosis factor-related apoptosis-inducing ligand to HepG2 cells is enhanced by Tan IIA in a pilot study, which may be attributed to low FLIPS levels induced by Tan IIA. In short, Tan IIA simultaneously induces both Nec-1 inhibition and FLIPS regulation-mediated apoptosis/necroptosis, which has not been previously documented. Moreover, the involvement of the cleavage type of MLKL in executing necroptosis warrants further investigation.
RESUMO
Mutations in SETD2, a histone H3 lysine trimethyltransferase, have been identified in clear cell renal cell carcinoma (ccRCC); however it is unclear if loss of SETD2 function alters the genomic distribution of histone 3 lysine 36 trimethylation (H3K36me3) in ccRCC. Furthermore, published epigenomic profiles are not specific to H3K36me3 or metastatic tumors. To determine if progressive SETD2 and H3K36me3 dysregulation occurs in metastatic tumors, H3K36me3, SETD2 copy number (CN) or SETD2 mRNA abundance was assessed in two independent cohorts: metastatic ccRCC (n=71) and the Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma data set (n=413). Although SETD2 CN loss occurs with high frequency (>90%), H3K36me3 is not significantly impacted by monoallelic loss of SETD2. H3K36me3-positive nuclei were reduced an average of ~20% in primary ccRCC (90% positive nuclei in uninvolved vs 70% positive nuclei in ccRCC) and reduced by ~60% in metastases (90% positive in uninvolved kidney vs 30% positive in metastases) (P<0.001). To define a kidney-specific H3K36me3 profile, we generated genome-wide H3K36me3 profiles from four cytoreductive nephrectomies and SETD2 isogenic renal cell carcinoma (RCC) cell lines using chromatin immunoprecipitation coupled with high-throughput DNA sequencing and RNA sequencing. SETD2 loss of methyltransferase activity leads to regional alterations of H3K36me3 associated with aberrant RNA splicing in a SETD2 mutant RCC and SETD2 knockout cell line. These data suggest that during progression of ccRCC, a decline in H3K36me3 is observed in distant metastases, and regional H3K36me3 alterations influence alternative splicing in ccRCC.
Assuntos
Carcinoma de Células Renais/metabolismo , Histonas/metabolismo , Neoplasias Renais/metabolismo , Lisina/metabolismo , Metástase Neoplásica , Carcinoma de Células Renais/patologia , Imunoprecipitação da Cromatina , Estudos de Coortes , Histonas/química , Humanos , Neoplasias Renais/patologia , MetilaçãoRESUMO
Heat-shock protein 5 (HSPA5) is a marker for poor prognosis in breast cancer patients and has an important role in cancer progression, including promoting drug resistance and metastasis. In this study, we identify that the specific lysine residue 447 (K447) of HSPA5 could be modified with polyubiquitin for subsequent degradation through the ubiquitin proteasomal system, leading to the suppression of cell migration and invasion of breast cancer. We further found that GP78, an E3 ubiquitin ligase, interacted with the C-terminal region of HSPA5 and mediated HSPA5 ubiquitination and degradation. Knock down of GP78 significantly increased the expression of HSPA5 and enhanced migration/invasive ability of breast cancer cells. Knock down of histone deacetylase-6 (HDAC6) increased the acetylation of HSPA5 at lysine residues 353 (K353) and reduced GP78-mediated ubiquitination of HSPA5 at K447 and then increased cell migration/invasion. In addition, we demonstrate that E3 ubiquitin ligase GP78 preferentially binds to deacetylated HSPA5. Notably, the expression levels of GP78 inversely correlated with HSPA5 levels in breast cancer patients. Patients with low GP78 expression significantly correlated with invasiveness of breast cancer, advanced tumor stages and poor clinical outcome. Taken together, our results provide new mechanistic insights into the understanding that deacetylation of HSPA5 by HDAC6 facilitates GP78-mediated HSPA5 ubiquitination and suggest that post-translational regulation of HSPA5 protein is critical for HSPA5-mediated metastatic properties of breast cancer.
Assuntos
Neoplasias da Mama/metabolismo , Proteínas de Choque Térmico/metabolismo , Histona Desacetilases/metabolismo , Acetilação , Sequência de Aminoácidos , Animais , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Chaperona BiP do Retículo Endoplasmático , Feminino , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/genética , Desacetilase 6 de Histona , Histona Desacetilases/genética , Humanos , Camundongos SCID , Dados de Sequência Molecular , Invasividade Neoplásica , Metástase Neoplásica , Complexo de Endopeptidases do Proteassoma/metabolismo , Homologia de Sequência de Aminoácidos , UbiquitinaçãoRESUMO
In the absence of extracellular stimulation the adaptor protein growth factor receptor-bound protein (Grb2) and the phospholipase Plcγ1 compete for the same binding site on fibroblast growth factor receptor 2 (FGFR2). Reducing cellular Grb2 results in upregulation of Plcγ1 and depletion of the phospholipid PI(4,5)P2. The functional consequences of this event on signaling pathways are unknown. We show that the decrease in PI(4,5)P2 level under non-stimulated conditions inhibits PTEN activity leading to the aberrant activation of the oncoprotein Akt. This results in excessive cell proliferation and tumor progression in a xenograft mouse model. As well as defining a novel mechanism of Akt phosphorylation with important therapeutic consequences, we also demonstrate that differential expression levels of FGFR2, Plcγ1 and Grb2 correlate with patient survival. Oncogenesis through fluctuation in the expression levels of these proteins negates extracellular stimulation or mutation and defines them as novel prognostic markers in ovarian cancer.
Assuntos
Proteína Adaptadora GRB2/genética , Proteína Oncogênica v-akt/genética , Neoplasias Ovarianas/genética , PTEN Fosfo-Hidrolase/genética , Fosfolipase C gama/genética , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/genética , Animais , Carcinogênese/genética , Proliferação de Células/genética , Feminino , Proteína Adaptadora GRB2/antagonistas & inibidores , Regulação Neoplásica da Expressão Gênica , Humanos , Camundongos , Neoplasias Ovarianas/patologia , PTEN Fosfo-Hidrolase/antagonistas & inibidores , Fosfatidilinositol 3-Quinases/genética , Fosfatidilinositóis/metabolismo , Fosfolipase C gama/biossíntese , Prognóstico , Receptor Tipo 2 de Fator de Crescimento de Fibroblastos/biossíntese , Transdução de SinaisRESUMO
BACKGROUND: Activation of the PI3K/mTOR and Hedgehog (Hh) signalling pathways occurs frequently in biliary tract cancer (BTC). Crosstalk between these pathways occurs in other gastrointestinal cancers. The respective signalling inhibitors rapamycin and vismodegib may inhibit BTC synergistically and suppress cancer stem cells (CSCs). METHODS: Gene expression profiling for p70S6k and Gli1 was performed with BTC cell lines. Tumour and pathway inhibitory effects of rapamycin and vismodegib were investigated in BTC preclinical models and CSCs. RESULTS: Rapamycin and vismodegib synergistically reduced BTC cell viability and proliferation. This drug combination arrested BTC Mz-ChA-1 cells in the G1 phase but had no significant effect on the cell cycle of BTC Sk-ChA-1 cells. Combined treatment inhibited the proliferation of CSCs and ALDH-positive cells. Nanog and Oct-4 expression in CSCs was decreased by the combination treatment. Western blotting results showed the p-p70S6K, p-Gli1, p-mTOR, and p-AKT protein expression were inhibited by the combination treatment in BTC cells. In an Mz-ChA-1 xenograft model, combination treatment resulted in 80% inhibition of tumour growth and prolonged tumour doubling time. In 4 of 10 human BTC specimens, tumour p-p70S6K and Gli1 protein expression levels were decreased with the combination treatment. CONCLUSIONS: Targeted inhibition of the PI3K/mTOR and Hhpathways indicates a new avenue for BTC treatment with combination therapy.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias do Sistema Biliar/tratamento farmacológico , Proteínas Hedgehog/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/antagonistas & inibidores , Anilidas/administração & dosagem , Animais , Neoplasias do Sistema Biliar/genética , Neoplasias do Sistema Biliar/metabolismo , Neoplasias do Sistema Biliar/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Fase G1/efeitos dos fármacos , Fase G1/genética , Perfilação da Expressão Gênica , Proteínas Hedgehog/genética , Proteínas Hedgehog/metabolismo , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Humanos , Camundongos , Camundongos Nus , Proteína Homeobox Nanog , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/metabolismo , Fator 3 de Transcrição de Octâmero/genética , Fator 3 de Transcrição de Octâmero/metabolismo , Piridinas/administração & dosagem , Proteínas Quinases S6 Ribossômicas 70-kDa/genética , Proteínas Quinases S6 Ribossômicas 70-kDa/metabolismo , Sirolimo/administração & dosagem , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto , Proteína GLI1 em Dedos de ZincoRESUMO
Epidermal growth factor receptor (EGFR) and human EGFR 2 (HER2) have an important role in the initiation and progression of various types of cancer. Inhibitors targeting these receptor tyrosine kinases are some of the most successful targeted anticancer drugs widely used for cancer treatment; however, cancer cells have mechanisms of intrinsic and acquired drug resistance that pose as major obstacles in drug efficacy. Extensive studies from both clinical and laboratory research have identified several molecular mechanisms underlying resistance. Among them is the role of signaling cross-talk between the EGFR/HER2 and other signaling pathways. In this review, we focus particularly on this signaling cross-talk at the receptor, mediator and effector levels, and further discuss alternative approaches to overcome resistance. In addition to well-recognized signaling cross-talk involved in the resistance, we also introduce the cross-talk between EGFR/HER2-mediated pathways and pathways triggered by other types of receptors, including those of the Notch, Wnt and TNFR/IKK/NF-κB pathways, and discuss the potential role of targeting this cross-talk to sensitize cells to EGFR/HER2 inhibitors.
Assuntos
Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Receptores ErbB/antagonistas & inibidores , Receptor Cross-Talk/efeitos dos fármacos , Receptor ErbB-2/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Animais , Humanos , Terapia de Alvo Molecular/métodos , Neoplasias/tratamento farmacológicoRESUMO
Receptor tyrosine kinases (RTKs) are cell surface receptors that initiate signal cascades in response to ligand stimulation. Abnormal expression and dysregulated intracellular trafficking of RTKs have been shown to be involved in tumorigenesis. Recent evidence shows that these cell surface receptors translocate from cell surface to different cellular compartments, including the Golgi, mitochondria, endoplasmic reticulum (ER) and the nucleus, to regulate physiological and pathological functions. Although some trafficking mechanisms have been resolved, the mechanism of intracellular trafficking from cell surface to the Golgi is not yet completely understood. Here we report a mechanism of Golgi translocation of epidermal growth factor receptor (EGFR) in which EGF-induced EGFR travels to the Golgi via microtubule-dependent movement by interacting with dynein and fuses with the Golgi through syntaxin 6-mediated membrane fusion. We also demonstrate that the microtubule- and syntaxin 6-mediated Golgi translocation of EGFR is necessary for its consequent nuclear translocation and nuclear functions. Thus, together with previous studies, the microtubule- and syntaxin 6-mediated trafficking pathway from cell surface to the Golgi, ER and the nucleus defines a comprehensive trafficking route for EGFR to travel from cell surface to the Golgi and the nucleus.
Assuntos
Núcleo Celular/metabolismo , Receptores ErbB/metabolismo , Complexo de Golgi/metabolismo , Microtúbulos/metabolismo , Proteínas Qa-SNARE/metabolismo , Movimento Celular/fisiologia , Dineínas/genética , Dineínas/metabolismo , Receptores ErbB/antagonistas & inibidores , Receptores ErbB/genética , Técnicas de Silenciamento de Genes , Células HeLa , Humanos , Transporte Proteico , Proteínas Qa-SNARE/genética , RNA Interferente Pequeno/administração & dosagem , RNA Interferente Pequeno/genéticaRESUMO
There are currently no effective therapies for cancer patients with advanced ovarian cancer, therefore developing an efficient and safe strategy is urgent. To ensure cancer-specific targeting, efficient delivery, and efficacy, we developed an ovarian cancer-specific construct (Survivin-VISA-hEndoyCD) composed of the cancer specific promoter survivin in a transgene amplification vector (VISA; VP16-GAL4-WPRE integrated systemic amplifier) to express a secreted human endostatin-yeast cytosine deaminase fusion protein (hEndoyCD) for advanced ovarian cancer treatment. hEndoyCD contains an endostatin domain that has tumor-targeting ability for anti-angiogenesis and a cytosine deaminase domain that converts the prodrug 5-fluorocytosine (5-FC) into the chemotherapeutic drug, 5-fluorouracil. Survivin-VISA-hEndoyCD was found to be highly specific, selectively express secreted hEndoyCD from ovarian cancer cells, and induce cancer-cell killing in vitro and in vivo in the presence of 5-FC without affecting normal cells. In addition, Survivin-VISA-hEndoyCD plus 5-FC showed strong synergistic effects in combination with cisplatin in ovarian cancer cell lines. Intraperitoneal (i.p.) treatment with Survivin-VISA-hEndoyCD coupled with liposome attenuated tumor growth and prolonged survival in mice bearing advanced ovarian tumors. Importantly, there was virtually no severe toxicity when hEndoyCD is expressed by Survivin-VISA plus 5-FC compared with CMV plus 5-FC. Thus, the current study demonstrates an effective cancer-targeted gene therapy that is worthy of development in clinical trials for treating advanced ovarian cancer.
Assuntos
Flucitosina/uso terapêutico , Fusão Gênica , Terapia Genética/métodos , Neoplasias Ovarianas/terapia , Animais , Linhagem Celular Tumoral , Citosina Desaminase/genética , Endostatinas/genética , Feminino , Humanos , Camundongos , Proteínas Recombinantes de Fusão/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Though the early integration of mesenchymal stem cells (MSCs) into tumor-associated stroma of cancer has been demonstrated, the functional contributions and underlying mechanisms of these cells to tumor growth and angiogenesis remain to be clarified. Using a xenograft model, human colorectal cancer cells, MSCs, and their cell mixture were introduced to a subcutaneous site of immunodeficient mice. The tumor growth rate and angiogenesis of each transplantation was then compared. We demonstrate that a variety of colorectal cancer cells, when mixed with otherwise non-tumorigenic MSCs, increase the tumor growth rate and angiogenesis more than that when mixed with carcinoma-associated fibroblasts or normal colonic fibroblasts. The secretion of interleukin-6 (IL-6) from MSCs increases the secretion of endothelin-1 (ET-1) in cancer cells, which induces the activation of Akt and ERK in endothelial cells, thereby enhancing their capacities for recruitment and angiogenesis to tumor. The IL-6/ET-1/Akt or ERK pathway of tumor-stroma interaction can be targeted by an antibody against IL-6 or Lentiviral-mediated RNAi against IL-6 in MSCs, by inhibition or knockdown of ET-1 in cancer cells, or by inhibition of ERK and Akt in host endothelial cells. These demonstrate that attempts to interrupt the interaction of MSCs and cancer cells help to abrogate angiogenesis and inhibit tumor growth in tumors formed by cancer cells admixed with MSCs. These data demonstrate that the tumor microenvironment, namely, MSCs-secreted IL-6, may enrich the proangiognic factors secreted by cancer cells to increase angiogenesis and tumor growth and that targeting this interaction may lead to novel therapeutic and preventive strategies.
Assuntos
Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Células-Tronco Mesenquimais/metabolismo , Neovascularização Patológica/metabolismo , Animais , Linhagem Celular Tumoral , Proliferação de Células , Modelos Animais de Doenças , Endotelina-1/metabolismo , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Humanos , Interleucina-6/metabolismo , Mucosa Intestinal/metabolismo , Mucosa Intestinal/patologia , Camundongos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Transplante HeterólogoRESUMO
Resveratrol, a phytochemical found in various plants and Chinese herbs, is associated with multiple tumor-suppressing activities, has been tested in clinical trials. However, the molecular mechanisms involved in resveratrol-mediated tumor suppressing activities are not yet completely defined. Here, we showed that treatment with resveratrol inhibited cell mobility through induction of the mesenchymal-epithelial transition (MET) in lung cancer cells. We also found that downregulation of FOXC2 (forkhead box C2) is critical for resveratrol-mediated suppression of tumor metastasis in an in vitro and in vivo models. We also identified a signal cascade, namely, resveratrol-â£miRNA-520h-â£PP2A/C-â£Akt â NF-κB â FOXC2, in which resveratrol inhibited the expression of FOXC2 through regulation of miRNA-520h-mediated signal cascade. This study identified a new miRNA-520h-related signal cascade involved in resveratrol-mediated tumor suppression activity and provide the clinical significances of miR-520h, PP2A/C and FOXC2 in lung cancer patients. Our results indicated a functional link between resveratrol-mediated miRNA-520h regulation and tumor suppressing ability, and provide a new insight into the role of resveratrol-induced molecular and epigenetic regulations in tumor suppression.
Assuntos
Antineoplásicos Fitogênicos/farmacologia , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/metabolismo , MicroRNAs/genética , Estilbenos/farmacologia , Animais , Linhagem Celular , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Progressão da Doença , Regulação para Baixo/efeitos dos fármacos , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/genética , Feminino , Células HEK293 , Humanos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Camundongos , Camundongos SCID , MicroRNAs/metabolismo , NF-kappa B/genética , NF-kappa B/metabolismo , Proteína Fosfatase 2/genética , Proteína Fosfatase 2/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Resveratrol , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Epidermal growth factor receptor (EGFR)-mediated cell signaling is critical for mammary epithelial cell growth and survival; however, targeting EGFR has shown no or only minimal therapeutic benefit in patients with breast cancer. Here, we report a novel regulatory mechanism of EGFR signaling that may explain the low response rates. We found that breast tumor kinase (Brk)/protein-tyrosine kinase 6 (PTK6), a nonreceptor protein-tyrosine kinase highly expressed in most human breast tumors, interacted with EGFR and sustained ligand-induced EGFR signaling. We demonstrate that Brk inhibits ligand-induced EGFR degradation through uncoupling activated EGFR from casitas B-lineage lymphoma-mediated EGFR ubiquitination. In addition, upon activation by EGFR, Brk directly phosphorylated Y845 in the EGFR kinase domain, thereby further potentiating EGFR kinase activity. Experimental elevation of Brk conferred resistance of breast cancer cells to cetuximab (an EGFR-blocking antibody)-induced inhibition of cell signaling and proliferation, whereas knockdown of Brk sensitized the cells to cetuximab by inducing apoptosis. Our findings reveal a previously unknown role of Brk in EGFR-targeted therapy.
Assuntos
Receptores ErbB/metabolismo , Genes erbB-1/genética , Proteínas de Neoplasias/metabolismo , Proteínas Tirosina Quinases/metabolismo , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais Humanizados , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Apoptose/efeitos dos fármacos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Cetuximab , Humanos , Proteínas de Neoplasias/genética , Proteínas Tirosina Quinases/genética , RNA Interferente Pequeno/farmacologia , Transdução de Sinais , Transativadores/metabolismoRESUMO
Accumulated evidence shows that EZH2 is deregulated in a wide range of cancer types, and it has a crucial role in stem cell maintenance and tumour development. Therefore, blocking EZH2 expression or activity may represent a promising strategy for anticancer treatment. In this review, we address the current understanding of the mechanisms underlying EZH2 regulation alongside the function of EZH2 gene targets that are involved in cancer progression. Finally, we will describe cancer therapies that target EZH2 or its downstream cascades, which could potentially reverse the oncogenic and stemness properties of the tumour cells to suppress cancer progression and recurrence.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Neoplasias/fisiopatologia , Fatores de Transcrição/fisiologia , Cromatina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Progressão da Doença , Proteína Potenciadora do Homólogo 2 de Zeste , Humanos , Neoplasias/metabolismo , Neoplasias/patologia , Células-Tronco Neoplásicas/patologia , Complexo Repressor Polycomb 2 , Fatores de Transcrição/metabolismoRESUMO
Hepatocellular carcinoma (HCC), the third leading cause of cancer death in the world, is the most general type of primary liver cancer. Although current treatment modalities, such as liver transplantation, resection, percutaneous ablation, transarterial embolization, chemotherapy and radiotherapy are potentially curative, these methods are not universally applicable to all of HCC patients, especially for those with poor prognosis in which no effective remedy is available. Therefore, development of novel therapeutic approach for the treatment of HCC is urgently needed. In the current study, we developed a promising HCC-targeted gene therapy vector driven by liver cancer-specific α-fetoprotein promoter/enhancer coupled to an established platform technology. The activity of this expression vector is comparable with or even higher than that of strong cytomegalovirus (CMV) promoter and exhibits strong promoter activity in liver cancer cells/tumors, but has nearly no or very low activity in normal cells/organs in vitro and in orthotopic animal models in vivo. Its cancer specificity exceeds that of the CMV promoter, which expresses non-specifically in both normal and tumor cells. In addition, targeted expression of a therapeutic BikDD, a mutant of proapoptotic gene Bik effectively and preferentially killed liver cancer cells, but not normal cells and significantly repressed growth of HCC tumors, and prolonged survival in multiple xenograft and syngeneic orthotopic mouse models of HCC through intravenous systemic gene delivery. Importantly, systemic administration of BikDD by our expression vector exerted no systemically acute toxicity compared with CMV-BikDD in mice. Taken together, this study elucidates a relatively safe and highly effective and specific systemic gene therapy strategy for liver cancer, and is worthy of further development for future clinical trials.
Assuntos
Terapia Genética , Neoplasias Hepáticas Experimentais/terapia , Animais , Elementos Facilitadores Genéticos , Neoplasias Hepáticas Experimentais/patologia , Camundongos , Regiões Promotoras Genéticas , alfa-Fetoproteínas/genéticaRESUMO
The PI3K/AKT signaling pathway is aberrant in a wide variety of cancers. Downstream effectors of AKT are involved in survival, growth and metabolic-related pathways. In contrast, contradictory data relating to AKT effects on cell motility and invasion, crucial prometastatic processes, have been reported pointing to a potential cell type and isoform type-specific AKT-driven function. By implication, study of AKT signaling should optimally be conducted in an appropriate intracellular environment. Prognosis in soft-tissue sarcoma (STS), the aggressive malignancies of mesenchymal origin, is poor, reflecting our modest ability to control metastasis, an effort hampered by lack of insight into molecular mechanisms driving STS progression and dissemination. We examined the impact of the cancer progression-relevant AKT pathway on the mesenchymal tumor cell internal milieu. We demonstrate that AKT1 activation induces STS cell motility and invasiveness at least partially through a novel interaction with the intermediate filament vimentin (Vim). The binding of AKT (tail region) to Vim (head region) results in Vim Ser39 phosphorylation enhancing the ability of Vim to induce motility and invasion while protecting Vim from caspase-induced proteolysis. Moreover, vimentin phosphorylation was shown to enhance tumor and metastasis growth in vivo. Insights into this mesenchymal-related molecular mechanism may facilitate the development of critically lacking therapeutic options for these devastating malignancies.
Assuntos
Movimento Celular , Mesoderma/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Sarcoma/metabolismo , Neoplasias de Tecidos Moles/metabolismo , Vimentina/metabolismo , Animais , Western Blotting , Linhagem Celular Tumoral , Imunofluorescência , Humanos , Imunoprecipitação , Mesoderma/patologia , Camundongos , Camundongos SCID , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Proteínas Proto-Oncogênicas c-akt/genética , Sarcoma/genética , Sarcoma/patologia , Transdução de Sinais/fisiologia , Neoplasias de Tecidos Moles/genética , Neoplasias de Tecidos Moles/patologia , TransfecçãoRESUMO
Histone deacetylase inhibitors (HDACi) are potent anti-cancer agents for variety of cancer types. Suberoylanilide hydroxamic acid (SAHA) has been approved as a drug to treat cutaneous T cell lymphoma, and the combination of HDACi and other agents have been actively tested in many clinical trials. Adenovirus 5 early region 1A (E1A) has been shown to exhibit high tumor suppressor activity, and gene therapy using E1A has been tested in clinical trials. Here, we showed that proapoptotic activity of HDACi was robustly enhanced by E1A in multiple cancer cells, but not in normal cells. Moreover, we showed that combination of E1A gene therapy and SAHA showed high therapeutic efficacy with low toxicity in vivo ovarian and breast xenograft models. SAHA downregulated Bcl-XL and upregulated proapoptotic BH3-only protein Bim, whose expression was further enhanced by E1A in cancer cells. These alterations of Bcl-2 family proteins were critical for apoptosis induced by the combination in cancer cells. SAHA enhanced acetylation of histone H3 in Bim promoter region, while E1A upregulated Egr-1, which was directly involved in Bim transactivation. Together, our results provide not only a novel insight into the mechanisms underlying anti-tumor activity of E1A, but also a rationale for the combined HDACi and E1A gene therapy in future clinical trials.
Assuntos
Proteínas E1 de Adenovirus/fisiologia , Proteínas Reguladoras de Apoptose/metabolismo , Apoptose/efeitos dos fármacos , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Acetilação/efeitos dos fármacos , Proteínas E1 de Adenovirus/genética , Animais , Proteínas Reguladoras de Apoptose/genética , Proteína 11 Semelhante a Bcl-2 , Western Blotting , Linhagem Celular , Linhagem Celular Tumoral , Montagem e Desmontagem da Cromatina/efeitos dos fármacos , Imunoprecipitação da Cromatina , Proteína 1 de Resposta de Crescimento Precoce/genética , Feminino , Terapia Genética , Histonas/metabolismo , Humanos , Ácidos Hidroxâmicos/farmacologia , Proteínas de Membrana/genética , Camundongos , Neoplasias Experimentais/genética , Neoplasias Experimentais/patologia , Neoplasias Experimentais/terapia , Proteínas Proto-Oncogênicas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Regulação para Cima/efeitos dos fármacos , Vorinostat , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Multiple membrane-bound receptor tyrosine kinases (RTKs), such as the epidermal growth factor receptor (EGFR) and ErbB-2, have been reported to be localized in the nucleus, where emerging evidence suggests that they are involved in transcriptional regulation, cell proliferation, DNA repair and chemo- and radio-resistance. Recent studies have shown that endocytosis and endosomal sorting are involved in the nuclear transport of cell surface RTKs. However, the detailed mechanism by which the full-length receptors embedded in the endosomal membrane travel all the way from the cell surface to the early endosomes and pass through the nuclear pore complexes is unknown. This important area has been overlooked for decades, which has hindered progress in our understanding of nuclear RTKs' functions. Here, we discuss the putative mechanisms by which EGFR family RTKs are shuttled into the nucleus. Understanding the trafficking mechanisms as to how RTKs are transported from the cell surface to the nucleus will significantly contribute to understanding the functions of the nuclear RTKs.