RESUMO
OBJECTIVE: To evaluate the therapeutic potential of vitamin D receptor (VDR) signaling in adrenocortical carcinoma (ACC) cells. METHODS: We evaluated VDR's methylation pattern in H295R ACC cells, and investigated the effects of calcitriol and seocalcitol treatments on adrenocortical tumorigenesis. RESULTS: VDR was hypermethylated and underexpressed in basal H295R cells. Treatments with calcitriol and seocalcitol restored VDR signaling, resulted in antiproliferative effects, and impaired Wnt/B-catenin signaling. RNAseq of treated cells demonstrated VDR activation on steroid hormones biosynthesis and Rap1 signaling, among others. In vivo, seocalcitol constrained the growth of H295R xenografts and reduced autonomous tumor steroid secretion without hypercalcemia-associated side effects. CONCLUSIONS: H295R cells present VDR hypermethylation, which can be responsible for its underexpression and signaling inactivation under basal conditions. VDR signaling promoted antiproliferative effects in vitro and in vivo, suggesting that it may be a potential therapeutic target for ACC and a valuable tool for patient's clinical management.
Assuntos
Neoplasias do Córtex Suprarrenal , Carcinoma Adrenocortical , Humanos , Neoplasias do Córtex Suprarrenal/tratamento farmacológico , Neoplasias do Córtex Suprarrenal/genética , Carcinoma Adrenocortical/tratamento farmacológico , Carcinoma Adrenocortical/genética , Calcitriol/farmacologia , Carcinogênese/genética , Cateninas/farmacologia , Linhagem Celular Tumoral , Transformação Celular Neoplásica , Hormônios/farmacologia , Receptores de Calcitriol/genética , Vitamina D/farmacologia , Via de Sinalização WntRESUMO
Glioblastoma multiforme (GBM) is a lethal tumor and novel strategies are required to overcome resistance. Transcription factor 12 (HEB) has been associated with neural and stem cell proliferation, is overexpressed in certain tumor types and is induced in irradiated U87MG cells. The present study aimed to determine whether HEB knockdown, with or without irradiation, may sensitize GBM cells. U87MG GBM and ACBRI371 primary human astrocytes were cultured in monolayers or neurospheres. Cell proliferation and death, cell cycle and subG1 detection, and cluster of differentiation (CD) 133 immunofluorescence were analyzed by flow cytometry, whereas HEB protein expression was analyzed by immunocytochemistry and western blotting. Greater HEB protein expression was observed in U87MG neurospheres compared with ACBRI371, and the two cell lines exhibited nuclear HEB expression. HEB silencing in cells grown in monolayers induced a significant reduction in proliferation and decreased the proportion of cells in G0/G1 phase. In addition, HEB silencing reduced (twofold) the number of neurospheres compared with control scrambled (SCR) cells. HEB silencing combined with irradiation reduced U87MG cell proliferation when cultured in monolayers and reduced neurosphere cell number compared with the SCR irradiated group; however, not significantly. Differentiation of U87MG cells from neurospheres was reduced in HEBsilenced cells, whereas in irradiated cells the proportion of CD133+ cells was similar in HEBsilenced cells compared with the SCR control. These results suggest that HEB may contribute to the proliferation and maintenance of GBM cells. However, only limited effects were exerted by irradiation in HEBsilenced cells. HEB may be a potential target to decrease proliferation in U87MG GBM cells, grown as monolayers or neurospheres, and may provide important information for the development of novel strategies for cancer therapy.
Assuntos
Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Inativação Gênica , Apoptose/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Biomarcadores , Ciclo Celular/genética , Linhagem Celular Tumoral , Proliferação de Células , Glioblastoma/genética , Humanos , Interferência de RNA , RNA Interferente Pequeno , Esferoides Celulares , Células Tumorais CultivadasRESUMO
BACKGROUND: The photodynamic therapy (PDT) has been used to treat cancer mainly by inducing oxidative stress. Our aim was to evaluate the effect of PDT and its combination with methoxyamine (MX), a blocker of base excision repair (BER), in cells expressing high levels of the APE1 protein, which is involved in cell oxidative damage response. METHODS: The HeLa and A549 cells were treated for 3h with chloroaluminum phthalocyanine incorporated into a well-designed nanoemulsion (ClAlPc/NE); and then irradiated by visible light (@670nm) with doses of 0.1, 0.5 and 1.0J/cm2. A simultaneous combination of MX+ClAlPc/NE was performed and then irradiated with the selected dose of 0.5J/cm2. The treatments were evaluated in terms of viability, clonogenicity, DNA fragmentation, and cell death mechanism by apoptosis and/or necrosis. RESULTS: The APE1 protein expression observed was higher in HeLa than in A549. Both cell lines exhibited substantial differences in cell cytotoxicity. The PDT decreased the clonogenicity of HeLa by inducing apoptosis (sub-G1 and annexin detection). Additionaly, the MX potentiates the PDT-effects in HeLa. Otherwise, low cytotoxicity was observed in A549 cells. CONCLUSION: The PDT induced apoptosis in high APE1 expressive HeLa cells, and the blockage of BER by MX increased its effects.
Assuntos
Apoptose/efeitos dos fármacos , Indóis/administração & dosagem , Indóis/química , Nanocápsulas/química , Neoplasias Experimentais/tratamento farmacológico , Compostos Organometálicos/administração & dosagem , Compostos Organometálicos/química , Fotoquimioterapia/métodos , Células A549 , Apoptose/efeitos da radiação , Emulsões , Células HeLa , Humanos , Nanocápsulas/administração & dosagem , Nanocápsulas/ultraestrutura , Neoplasias Experimentais/patologia , Tamanho da Partícula , Fármacos Fotossensibilizantes/administração & dosagem , Fármacos Fotossensibilizantes/química , Resultado do TratamentoRESUMO
Contemporary anticancer therapies have largely improved the outcome for children with cancer, especially for Acute Lymphoblastic Leukemia (ALL). Actually, between 78% and 85% of patients achieve complete remission and are alive after 5 years of therapy completion. However, as cure rates increase, new concerns about the late effects of genotoxic treatment emerge, being the risk of developing secondary neoplasias, the most serious life-threatening rising problem. In the present paper, we describe and review the cytogenetic findings in peripheral lymphocytes from ALL survivors, and discuss aspects associated to the occurrence of increased chromosome rearrangements in this growing cohort.
Assuntos
Aberrações Cromossômicas/estatística & dados numéricos , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/mortalidade , Sobreviventes/estatística & dados numéricos , Adulto , Criança , Estudos de Coortes , Comorbidade , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/terapiaRESUMO
Topoisomerase II inhibitors are effective chemotherapeutic agents in the treatment of cancer, in spite of being associated with the development of secondary leukemia. Our purpose was to determine the effects of etoposide on different genomic regions, aiming at discovering whether there are preferential sites which can be targeted by this drug in peripheral lymphocytes from healthy individuals. The in vitro treatment with low doses of etoposide (0.25, 0.5, and 1 µg/mL, in 1 hour-pulse or continuous-48 h treatment) induced a significant increase in chromosomal aberrations, detected by conventional staining and FISH with specific probes for chromosomes 8 and 11, compared with untreated controls (p < 0.05). Additionally, the frequencies of alterations at 11q23, detected by MLL specific probes, were significantly higher (p < 0.005) in treated cells than in controls. In contrast, an analysis of rearrangements involving the IGH gene did not disclose differences between treatments. The present results demonstrated the potential of etoposide to interact with preferential chromosome sites in human lymphocytes, even at concentrations below the mean plasma levels measured in cancer patients. This greater susceptibility to etoposide-induced cleavage may explain the more frequent involvement of MLL in treatment-related leukemia.
RESUMO
Chromosomal translocations are characteristic of hematopoietic neoplasias and can lead to unregulated oncogene expression or the fusion of genes to yield novel functions. In recent years, different lymphoma/leukemia-associated rearrangements have been detected in healthy individuals. In this study, we used inverse PCR to screen peripheral lymphocytes from 100 healthy individuals for the presence of MLL (Mixed Lineage Leukemia) translocations. Forty-nine percent of the probands showed MLL rearrangements. Sequence analysis showed that these rearrangements were specific for MLL translocations that corresponded to t(4;11)(q21;q23) (66%) and t(9;11) (20%). However, RT-PCR failed to detect any expression of t(4;11)(q21;q23) in our population. We suggest that 11q23 rearrangements in peripheral lymphocytes from normal individuals may result from exposure to endogenous or exogenous DNA-damaging agents. In practical terms, the high susceptibility of the MLL gene to chemically-induced damage suggests that monitoring the aberrations associated with this gene in peripheral lymphocytes may be a sensitive assay for assessing genomic instability in individuals exposed to genotoxic stress.
RESUMO
Chromosomal translocations are characteristic of hematopoietic neoplasias and can lead to unregulated oncogene expression or the fusion of genes to yield novel functions. In recent years, different lymphoma/leukemia-associated rearrangements have been detected in healthy individuals. In this study, we used inverse PCR to screen peripheral lymphocytes from 100 healthy individuals for the presence of MLL (Mixed Lineage Leukemia) translocations. Forty-nine percent of the probands showed MLL rearrangements. Sequence analysis showed that these rearrangements were specific for MLL translocations that corresponded to t(4;11)(q21;q23) (66 percent) and t(9;11) (20 percent). However, RT-PCR failed to detect any expression of t(4;11)(q21;q23) in our population. We suggest that 11q23 rearrangements in peripheral lymphocytes from normal individuals may result from exposure to endogenous or exogenous DNA-damaging agents. In practical terms, the high susceptibility of the MLL gene to chemically-induced damage suggests that monitoring the aberrations associated with this gene in peripheral lymphocytes may be a sensitive assay for assessing genomic instability in individuals exposed to genotoxic stress.
RESUMO
Topoisomerase II inhibitors are effective chemotherapeutic agents in the treatment of cancer, in spite of being associated with the development of secondary leukemia. Our purpose was to determine the effects of etoposide on different genomic regions, aiming at discovering whether there are preferential sites which can be targeted by this drug in peripheral lymphocytes from healthy individuals. The in vitro treatment with low doses of etoposide (0.25, 0.5, and 1 µg/mL, in 1 hour-pulse or continuous-48 h treatment) induced a significant increase in chromosomal aberrations, detected by conventional staining and FISH with specific probes for chromosomes 8 and 11, compared with untreated controls (p < 0.05). Additionally, the frequencies of alterations at 11q23, detected by MLL specific probes, were significantly higher (p < 0.005) in treated cells than in controls. In contrast, an analysis of rearrangements involving the IGH gene did not disclose differences between treatments. The present results demonstrated the potential of etoposide to interact with preferential chromosome sites in human lymphocytes, even at concentrations below the mean plasma levels measured in cancer patients. This greater susceptibility to etoposide-induced cleavage may explain the more frequent involvement of MLL in treatment-related leukemia.