RESUMO
Gamma linolenic acid (GLA) possesses a number of selective anti-tumour properties including modulation of steroid receptor structure and function. We have investigated the effect of dietary GLA on the growth, oestrogen receptor (ER) expression and fatty acid profile of ER+ve human breast cancer xenografts. Experimental diets A, B, C, D were commenced after subcutaneous implantation of 40 female nude mice with the MCF-7 B1M cell line (Group A = control diet: B = control diet + GLA supplement: C = control diet + tamoxifen: D = control diet + GLA + tamoxifen; 10 mice/group). The mice were terminated when tumour cross-sectional area reached 250 mm(2). ER H-scores were assessed by immunohistochemical assay and fatty acid profiles by gas-liquid chromatography of termination tumour samples. Groups C and D displayed significantly slower tumour growth (p =.0002, p =.0006) with trend for slower growth in B (p =.065) compared to control Group A. ER was significantly reduced in all groups compared to A (p <.0001) with Group D (combined therapy) displaying markedly lower ER expression than with either therapy alone (p =.0002). There were significantly raised levels of tumour GLA and metabolites in the two groups (B and D) receiving GLA (p <.0001). This xenograft model of ER+ve breast cancer has demonstrated significantly lower tumour ER expression in those groups receiving GLA, an effect which appears to be additive to the reduced ER expression resulting from tamoxifen alone. The effects of GLA on ER function and the possibility of synergistic inhibitory action of GLA with tamoxifen via enhanced down-regulation of the ER pathway require further investigation.
Assuntos
Antineoplásicos Hormonais/farmacologia , Neoplasias da Mama/metabolismo , Ácidos Graxos/metabolismo , Expressão Gênica/efeitos dos fármacos , Receptores de Estrogênio/biossíntese , Tamoxifeno/farmacologia , Ácido gama-Linolênico/farmacologia , Animais , Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/genética , Neoplasias da Mama/prevenção & controle , Divisão Celular/efeitos dos fármacos , Suplementos Nutricionais , Modelos Animais de Doenças , Interações Medicamentosas , Quimioterapia Combinada , Humanos , Camundongos , Receptores de Estrogênio/efeitos dos fármacos , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Tamoxifeno/uso terapêutico , Ensaios Antitumorais Modelo de Xenoenxerto , Ácido gama-Linolênico/metabolismo , Ácido gama-Linolênico/uso terapêuticoRESUMO
Gamma linolenic acid (GLA) is a polyunsaturated fatty acid, which induces cytotoxicity and regulates cell adhesion in cancer cells. The molecular mechanism of these actions is not clear. We have shown that GLA acts via peroxisome proliferator activated receptors (PPARs), by stimulating their phosphorylation and translocation to the nucleus. Removing PPAR gamma with antisense oligos abolished the effect of GLA on the expression of adhesion molecules and tumour suppressor genes, whereas removal of PPAR alpha had no effect. Tissues from patients with breast cancer showed a reduction of expression of both PPARs in cancer tissues, as compared with normal. Thus, PPAR gamma serves as the receptor for GLA in the regulation of gene expression in breast cancer cells.
Assuntos
Neoplasias da Mama/metabolismo , Receptores Citoplasmáticos e Nucleares/fisiologia , Fatores de Transcrição/fisiologia , Ácido gama-Linolênico/farmacologia , Western Blotting , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Imunofluorescência , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Técnicas de Imunoadsorção , Oligonucleotídeos Antissenso/farmacologia , Fosforilação , Receptores Citoplasmáticos e Nucleares/análise , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/análise , Fatores de Transcrição/genética , Células Tumorais CultivadasRESUMO
Gamma linolenic acid (GLA) has been proposed as a valuable new cancer therapy having selective anti-tumour properties with negligible systemic toxicity. Proposed mechanisms of action include modulation of steroid hormone receptors. We have investigated the effects of GLA with primary hormone therapy in an endocrine-sensitive cancer. Thirty-eight breast cancer patients (20 elderly Stage I-II, 14 locally advanced, 4 metastatic) took 8 capsules of oral GLA/day (total = 2.8 g) in addition to tamoxifen 20 mg od (T+GLA). Quality and duration of response were compared with matched controls receiving tamoxifen 20 mg od alone (n = 47). Serial tumour biopsies were taken to assess changes in oestrogen receptor (ER) and bcl-2 expression during treatment. GLA was well tolerated with no major side effects. T+GLA cases achieved a significantly faster clinical response (objective response vs. static disease) than tamoxifen controls, evident by 6 weeks on treatment (p = 0.010). There was significant reduction in ER expression in both treatment arms with T+GLA objective responders sustaining greater ER fall than tamoxifen counterparts (6-week biopsy p = 0.026; 6-month biopsy p = 0.019). We propose GLA as a useful adjunct to primary tamoxifen in endocrine-sensitive breast cancer. The effects of GLA on ER function and the apparent enhancement of tamoxifen-induced ER down-regulation by GLA require further investigation.
Assuntos
Antineoplásicos Hormonais/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Tamoxifeno/uso terapêutico , Ácido gama-Linolênico/uso terapêutico , Administração Oral , Idoso , Antineoplásicos Hormonais/efeitos adversos , Biópsia , Neoplasias da Mama/patologia , Intervalo Livre de Doença , Feminino , Humanos , Pessoa de Meia-Idade , Metástase Neoplásica , Estadiamento de Neoplasias , Proteínas Proto-Oncogênicas c-bcl-2/análise , Receptores de Estrogênio/análise , Tamoxifeno/efeitos adversos , Ácido gama-Linolênico/administração & dosagem , Ácido gama-Linolênico/efeitos adversosAssuntos
Antineoplásicos/química , Antineoplásicos/uso terapêutico , Ácidos Graxos Essenciais/química , Ácidos Graxos Essenciais/uso terapêutico , Neoplasias/química , Animais , Antineoplásicos/toxicidade , Ácidos Graxos Essenciais/toxicidade , Humanos , Neoplasias/tratamento farmacológico , Neoplasias Experimentais/química , Neoplasias Experimentais/tratamento farmacológicoRESUMO
gamma-Linolenic acid (gamma-LA), a n-6 essential fatty acid, has been previously shown to affect cell cycle and growth of cancer cells. This study examined the effects of gamma-LA on the cell cycle and cycle regulators in human colon cancer HT115 and breast cancer MCF7 cells. Brief treatment of cancer cells (<2 h) with gamma-LA resulted in a decrease in the phosphorylation of both cell cycle inhibitors, p27kip1 and p57kip2 as shown by immunoprecipitation and Western blotting. Protein levels of both inhibitors were increased following a prolonged culture of cells with the fatty acid. A co-precipitation study showed that in cells treated with gamma-LA there was an increase in the binding of these inhibitors with CDK4, CDC2, and cyclin E. Flow cytometry study indicated an inhibition of cell cycle progression by gamma-LA (G0/G1 -45.4%, S - 34.6%, G2+M - 20.0% in control, and 70.5%, 21.0%, and 8.5%, respectively, in gamma-LA treated cells). It is concluded that gamma-linolenic acid inhibits cell cycle progression in the cancer cell lines investigated, via its regulation of the phosphorylation and subsequent degradation of p27kip1 and p57kip2 and their interactions with other cycle regulators.
Assuntos
Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Proteínas de Ciclo Celular , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Supressoras de Tumor , Ácido gama-Linolênico/farmacologia , Neoplasias da Mama/patologia , Ciclo Celular/efeitos dos fármacos , Neoplasias Colorretais/patologia , Inibidor de Quinase Dependente de Ciclina p27 , Inibidor de Quinase Dependente de Ciclina p57 , Ácidos Graxos/farmacologia , Citometria de Fluxo , Fase G1/efeitos dos fármacos , Humanos , Fosforilação , Fase de Repouso do Ciclo Celular/efeitos dos fármacosRESUMO
This study examined the effect of n-6 polyunsaturated fatty acids (PUFAs) on the expression of nm-23, a metastasis-suppressor gene, in two highly invasive human cancer cell lines, HT115 and MDA MB 231. A range of n-6 and n-3 PUFAs were tested. We report that while linoleic acid and arachidonic acid reduced the expression of nm-23-H1, gamma linolenic acid (GLA) and its soluble lithium salt markedly increased the expression of the molecules. The stimulation of the expression of nm-23 by GLA was seen at both protein and mRNA levels. Up-regulation of nm-23 was also associated with a reduction of the in vitro invasiveness of these cells. It is concluded that gamma linolenic acid (GLA) enhances the expression of nm-23. This contributes to the inhibition of the in vitro invasion of tumour cells.
Assuntos
Neoplasias da Mama/genética , Neoplasias do Colo/genética , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Ácido Linoleico/farmacologia , Proteínas Monoméricas de Ligação ao GTP , Proteínas de Neoplasias/biossíntese , Núcleosídeo-Difosfato Quinase , Fatores de Transcrição/biossíntese , Ácido gama-Linolênico/farmacologia , Ácido Araquidônico/farmacologia , Neoplasias da Mama/patologia , Neoplasias do Colo/patologia , Ensaios de Seleção de Medicamentos Antitumorais , Ácido Eicosapentaenoico/farmacologia , Humanos , Nucleosídeo NM23 Difosfato Quinases , Invasividade Neoplásica , Proteínas de Neoplasias/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , RNA Neoplásico/biossíntese , RNA Neoplásico/genética , Fatores de Transcrição/genética , Células Tumorais CultivadasRESUMO
Tight junctions (TJ) are the topical most structure in epithelial and endothelial cells and play a key role in the control of permeability and prevention of tumour cell invasion of endothelium. In this study we examined the effects of a range of polyunsaturated fatty acids on the function of TJs and the expression of occludin, a key molecule in the TJs of the human vascular endothelial cell line, ECV304. Treatment of the endothelial cells with gamma linolenic acid, an anti-cancer PUFA, increased the transendothelial cell resistance (TER) and reduced the paracellular permeability to large molecules. The effects were seen without any changes in the viability of the endothelial cells. Occludin, a recently identified molecule, which plays a major role in tight junctions was up-regulated by this fatty acid as revealed by both Western blotting and immunofluorescence. Other fatty acids were also tested. Eicosapentaenoic acid (EPA) also exerted an up-regulatory effect, but LA and AA down-regulated the expression. We conclude that GLA and EPA which also have other anti-cancer effects, regulate the expression of occludin in endothelial cells and thus contribute to the modification of the TER of these cells.
Assuntos
Ácidos Graxos Insaturados/farmacologia , Proteínas de Membrana/metabolismo , Junções Íntimas/efeitos dos fármacos , Junções Íntimas/metabolismo , Ácido Araquidônico/farmacologia , Linhagem Celular , Permeabilidade da Membrana Celular/efeitos dos fármacos , Ácido Eicosapentaenoico/farmacologia , Impedância Elétrica , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/metabolismo , Humanos , Ácido Linoleico/farmacologia , Ocludina , Ácido gama-Linolênico/farmacologiaRESUMO
Desmosomes are key structures in cell-cell adhesion. In this study we examined the effect of n-6 essential fatty acids on the expression of desmoglein (Dsg), desmosomal cadherin and the formation of desmosomes in E-cadherin negative human breast, colon and lung cancer cells and melanoma cells. Electron microscopy revealed that cells cultured with gamma linolenic acid (GLA) showed increased cell-cell adhesion together with an increase in the formation of desmoglein-containing desmosomes. Western blotting studies of cellular proteins demonstrated that, following culture with fatty acids, Dsg expression was modified, with the greatest increase seen after GLA treatment. Other fatty acids increased Dsg expression, but to a lesser extent. It is concluded that GLA regulates desmosome-mediated cell-cell adhesion in human cancer cells, particularly in cells without E-cadherin.
Assuntos
Caderinas/metabolismo , Adesão Celular , Proteínas do Citoesqueleto/metabolismo , Desmossomos/metabolismo , Neoplasias/metabolismo , Ácido gama-Linolênico/farmacologia , Movimento Celular/efeitos dos fármacos , Desmogleínas , Desmoplaquinas , Humanos , Neoplasias/patologia , Células Tumorais CultivadasRESUMO
Maspin, mammary serine protease inhibitor, is a recently identified tumour suppressor and has a profound effect on cell motility. This study examined the effect of gamma linolenic acid (GLA), an essential fatty acid (EFA) with anticancer properties, on the expression of maspin and motility of cancer cells. Six human cell lines including colon cancer, mammary cancer, and melanoma were used. Expression of maspin protein was determined by immunocytochemistry & Western blotting. Maspin mRNA was detected with reverse transcription-PCR (RT-PCR). Four of the six cell types expressed maspin with MDA MB 231 and ECV304 (endothelial cell) being negative. Treatment of these maspin positive cells with gamma linolenic acid (GLA) resulted in a concentration dependent stimulation of the expression of maspin protein with the effects seen as early as 4 hours. Linoleic acid had an inhibitory effects. Alpha linolenic acid and arachidonic acid had no significant effect. The mRNA levels from cells treated with GLA was seen to increase as shown by RT-PCR. Cell motility, monitored with time-lapse video recording and Hoffmann microscopy, showed a marked reduction in terms of spreading and migration on extracellular matrix coated surface. This reduction was reversed with anti-maspin antibody. It is concluded that GLA, a member of then-6 series of EFAs, up-regulates the expression of maspin which is associated with a reduction in the motility of cancer cells.
Assuntos
Movimento Celular/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Biossíntese de Proteínas , Proteínas , Serpinas/biossíntese , Transcrição Gênica/efeitos dos fármacos , Ácido gama-Linolênico/farmacologia , Neoplasias da Mama , Linhagem Celular , Movimento Celular/fisiologia , Neoplasias do Colo , Endotélio Vascular/efeitos dos fármacos , Endotélio Vascular/fisiologia , Ácidos Graxos não Esterificados/farmacologia , Feminino , Genes Supressores de Tumor , Humanos , Cinética , Melanoma , Reação em Cadeia da Polimerase , RNA Mensageiro/biossíntese , Inibidores de Serina Proteinase/metabolismo , Células Tumorais CultivadasRESUMO
Tumour-endothelial cell adhesion forms a key role in the establishment of distant metastases. This study examined the effect of gamma linolenic acid (GLA), an anti-cancer polyunsaturated fatty acid (PUFA), on both the gap junction communication of human vascular endothelial cells and tumour cell-endothelial interactions. By using scrape loading of Lucifer yellow dye, we showed that GLA at non-toxic levels increased Lucifer yellow transfer, indicating improved gap junction communication. The fatty acid also corrected the communication that was reduced by the mitogenic and motogenic factor HGF/SF. GLA inhibited the tyrosine phosphorylation of connexin-43, a protein that formed gap junction in this cell. When human tumour cells were added to quiescent or HGF/SF-activated endothelial cells, the presence of GLA reduced adhesion of tumour cells to the endothelium. It is concluded that GLA reduces tumour-endothelium adhesion, partly by improved gap junction communications of the endothelium.