RESUMO
The high mobility group A (HMGA) proteins are found to be aberrantly expressed in several tumors. Studies (in vitro and in vivo) have shown that HMGA protein overexpression has a causative role in carcinogenesis process. HMGA proteins regulate cell cycle progression through distinct mechanisms which strongly influence its normal dynamics along malignant transformation. Tumor protein p53 (TP53) is the most frequently altered gene in cancer. The loss of its activity is recognized as the fall of a barrier that enables neoplastic transformation. Among the different functions, TP53 signaling pathway is tightly involved in control of cell cycle, with cell cycle arrest being the main biological outcome observed upon p53 activation, which prevents accumulation of damaged DNA, as well as genomic instability. Therefore, the interaction and opposing effects of HMGA and p53 proteins on regulation of cell cycle in normal and tumor cells are discussed in this review. HMGA proteins and p53 may reciprocally regulate the expression and/or activity of each other, leading to the counteraction of their regulation mechanisms at different stages of the cell cycle. The existence of a functional crosstalk between these proteins in the control of cell cycle could open the possibility of targeting HMGA and p53 in combination with other therapeutic strategies, particularly those that target cell cycle regulation, to improve the management and prognosis of cancer patients.
Assuntos
Pontos de Checagem do Ciclo Celular/fisiologia , Proteínas HMGA/metabolismo , Neoplasias/patologia , Proteína Supressora de Tumor p53/metabolismo , Dano ao DNA , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Instabilidade Genômica , Proteínas HMGA/genética , Humanos , Neoplasias/genética , Neoplasias/metabolismo , Transdução de Sinais , Proteína Supressora de Tumor p53/genéticaRESUMO
AIMS: Linalool is a plant-derived monoterpene with anticancer activity, however its mechanisms of action remain poorly understood. The aim of this work was to elucidate the anticancer mechanisms of action of linalool in hepatocellular carcinoma (HCC) HepG2 cells. MAIN METHODS: Cell viability and proliferation were determined by WST-1 assay and BrdU incorporation, respectively. Cell cycle analysis was assessed through flow cytometry (FC) and western blot (WB). Apoptosis was determined by caspase-3 activity, TUNEL assay and WB. Reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were analyzed by FC and fluorescence microscopy. Expression of Ras, MAPKs (ERK, JNK and p38) and Akt/mTOR pathways were evaluated by WB. KEY FINDINGS: Linalool (0-2.5â¯mM) dose-dependently inhibited cell proliferation by inducing G0/G1 cell cycle arrest, through Cdk4 and cyclin A downregulation, p21 and p27 upregulation, and apoptosis, characterized by MMP loss, caspase-3 activation, PARP cleavage and DNA fragmentation. Low concentrations of linalool (1.0â¯mM) reduced membrane-bound Ras and Akt activity whereas higher amounts (2.0â¯mM) triggered mTOR inhibition and ROS generation, in correlation with MAPKs activation and Akt phosphorylation. ROS scavenger N-acetyl-L-cysteine partially rescued HepG2 cell growth and prevented MPP depolarization, ERK and JNK activation. Moreover, specific ERK and Akt phosphorylation inhibitors potentiated linalool anti-cancer activity, pointing Akt and ERK activation as pro-survival mechanisms in response to higher concentrations of linalool. SIGNIFICANCE: This report reveals that linalool induces G0/G1 arrest and apoptosis in HepG2 cells involving Ras, MAPKs and Akt/mTOR pathways and suggests that linalool is a promising anticancer agent for HCC therapy.
Assuntos
Apoptose/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Monoterpenos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/antagonistas & inibidores , Monoterpenos Acíclicos , Apoptose/fisiologia , Pontos de Checagem do Ciclo Celular/fisiologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/fisiologia , Relação Dose-Resposta a Droga , Células Hep G2 , Humanos , Sistema de Sinalização das MAP Quinases/fisiologia , Estresse Oxidativo/fisiologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Serina-Treonina Quinases TOR/antagonistas & inibidores , Serina-Treonina Quinases TOR/metabolismo , Proteínas ras/antagonistas & inibidores , Proteínas ras/metabolismoRESUMO
OBJECTIVES: Oral squamous cell carcinoma (OSCC) predominantly affects males in the fifth decade of life; nevertheless, an increased incidence in young patients has been reported worldwide, and the clinical and behavioral characteristics of tumors in this group are controversial, and the literature shows divergent results. PURPOSE: To investigate the clinicopathological features and prognostic significance of the immunoexpression of cell cycle and local invasion proteins in OSCC affecting young patients (≤40 years old). METHODS: A tissue microarray was performed with 132 OSCC samples (61 cases of young patients vs 71 cases of elderly patients) and submitted to immunohistochemical reactions with Ki67, p53, p16, Bcl-2, Cyclin D1, C-ErbB2, p21, Myc, EGFR, MMP-9, SMA, Cathepsin K and FGF-2 antibodies. RESULTS: Clinicopathological features and survival rates were similar in both groups. Although overexpression of EGFR (P=.042) and MMP-9 (P=.001) was more frequent in young patients, only C-ErbB-2 (P=.048) and SMA (P=.048) expression correlated with lower disease-free survival (DFS) in this group of patients. CONCLUSION: Clinicopathological features and survival rates are similar between younger and older patients with OSCC. The different patterns of C-ErbB2, EGFR, MMP-9, and SMA expression between the groups merits further investigation to understand their role in the early tumor onset in young patients.
Assuntos
Carcinoma de Células Escamosas/metabolismo , Pontos de Checagem do Ciclo Celular/fisiologia , Regulação Neoplásica da Expressão Gênica/fisiologia , Neoplasias Bucais/metabolismo , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/patologia , Catepsina K/metabolismo , Pontos de Checagem do Ciclo Celular/genética , Ciclina D1/metabolismo , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Intervalo Livre de Doença , Células Epiteliais/patologia , Receptores ErbB/metabolismo , Feminino , Fator 2 de Crescimento de Fibroblastos/metabolismo , Regulação Neoplásica da Expressão Gênica/genética , Humanos , Imuno-Histoquímica , Antígeno Ki-67/metabolismo , Masculino , Metaloproteinase 9 da Matriz/metabolismo , Pessoa de Meia-Idade , Neoplasias Bucais/genética , Neoplasias Bucais/mortalidade , Neoplasias Bucais/patologia , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Prognóstico , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Proteínas Proto-Oncogênicas c-myc/metabolismo , Receptor ErbB-2/metabolismo , Taxa de Sobrevida , Proteína Supressora de Tumor p53/metabolismoRESUMO
The Rad9-Rad1-Hus1 (9-1-1) complex is a key component in the coordination of DNA damage sensing, cell cycle progression and DNA repair pathways in eukaryotic cells. This PCNA-related trimer is loaded onto RPA-coated single stranded DNA and interacts with ATR kinase to mediate effective checkpoint signaling to halt the cell cycle and to promote DNA repair. Beyond these core activities, mounting evidence suggests that a broader range of functions can be provided by 9-1-1 structural diversification. The protozoan parasite Leishmania is an early-branching eukaryote with a remarkably plastic genome, which hints at peculiar genome maintenance mechanisms. Here, we investigated the existence of homologs of the 9-1-1 complex subunits in L. major and found that LmRad9 and LmRad1 associate with chromatin in response to replication stress and form a complex in vivo with LmHus1. Similar to LmHus1, LmRad9 participates in telomere homeostasis and in the response to both replication stress and double strand breaks. However, LmRad9 and LmHus1-deficient cells present markedly opposite phenotypes, which suggest their functional compartmentalization. We show that some of the cellular pool of LmRad9 forms an alternative complex and that some of LmHus1 exists as a monomer. We propose that the diverse assembly of the Leishmania 9-1-1 subunits mediates functional compartmentalization, which has a direct impact on the response to genotoxic stress.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Dano ao DNA/fisiologia , Exonucleases/metabolismo , Leishmania major/fisiologia , Pontos de Checagem do Ciclo Celular/fisiologia , Proteínas de Ligação a DNA/metabolismo , Leishmania major/genética , Leishmania major/metabolismoRESUMO
Senescence phenotype can be achieved by multiple pathways. Most of them involve the activation of negative cell cycle regulators as well as a shift to an oxidative status. However, the exact participation of these events in senescence establishment and maintenance is not completely understood. In this study we investigated the content of three final cell cycle regulators, as well as the redox state in some critical points during the pre-senescent and the full-senescent states. Our results highlight the existence of a critical pre-phase in senescent phenotype establishment, in which cell proliferation stops with the participation of the cell cycle inhibitors, and a second maintenance stage where the exacerbated pro-oxidant state inside the cell induces the physiological decline characteristic in senescent cells.
Assuntos
Senescência Celular/fisiologia , Fibroblastos/citologia , Fibroblastos/metabolismo , Animais , Antioxidantes/farmacologia , Pontos de Checagem do Ciclo Celular/fisiologia , Proliferação de Células , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Cromanos/farmacologia , DNA/biossíntese , Fibroblastos/efeitos dos fármacos , Glutationa/metabolismo , Dissulfeto de Glutationa/metabolismo , Camundongos , Oxirredução , Fenótipo , Carbonilação ProteicaRESUMO
Some studies show that alterations in expression of proteins related to mitotic spindle (AURORAS KINASE A and B) and mitotic checkpoint (CDC20 and MAD2L1) are involved in chromosomal instability and tumor progression in various solid and hematologic malignancies. This study aimed to evaluate these genes in MDS patients. The cytogenetics analysis was carried out by G-banding, AURKA and AURKB amplification was performed using FISH, and AURKA, AURKB, CDC20 and MAD2L1 gene expression was performed by qRT-PCR in 61 samples of bone marrow from MDS patients. AURKA gene amplification was observed in 10% of the cases, which also showed higher expression levels than the control group (p=0.038). Patients with normo/hypercellular BM presented significantly higher expression levels than hypocellular BM patients, but normo and hypercellular BM groups did not differ. After logistic regression analysis, our results showed that HIGH expression levels were associated with increased risk of developing normo/hypercellular MDS. It also indicated that age is associated with AURKA, CDC20 and MAD2L1 HIGH expression levels. The distinct expression of hypocellular patients emphasizes the prognostic importance of cellularity to MDS. The amplification/high expression of AURKA suggests that the increased expression of this gene may be related to the pathogenesis of disease.
Assuntos
Pontos de Checagem do Ciclo Celular/fisiologia , Proteínas de Ciclo Celular/fisiologia , Síndromes Mielodisplásicas/patologia , Fuso Acromático/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Cariótipo , Masculino , Pessoa de Meia-Idade , Síndromes Mielodisplásicas/classificação , Síndromes Mielodisplásicas/genética , Adulto JovemRESUMO
Gliomas are the most common and devastating tumors of the central nervous system (CNS). Many pieces of evidence point out the relevance of natural compounds for cancer therapy and prevention, including chalcones. In the present study, eight synthetic quinoxaline-derived chalcones, structurally based on the selective PI3Kγ inhibitor AS605240, were evaluated for anti-proliferative activity and viability inhibition using glioma cell lines from human and rat origin (U-138 MG and C6, respectively), at different time-periods of incubation and concentrations. The results revealed that four chalcones (compounds 1, 6, 7 and 8), which present methoxy groups at A-ring, displayed higher efficacies and potencies, being able to inhibit either cell proliferation or viability, in a time- and concentration-dependent manner, with an efficacy that was greater than that seen for the positive control compound AS605240. Flow cytometry analysis demonstrated that incubation of C6 cells with compound 6 led to G1 phase arrest, likely indicating an interference with apoptosis. Furthermore, compound 6 was able to visibly inhibit AKT activation, allied to the stimulation of ERK MAP-kinase. The chalcones tested herein, especially those displaying a methoxy substituent, might well represent promising molecules for the adjuvant treatment of glioma progression.