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1.
J Microbiol ; 58(7): 550-562, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32281050

RESUMO

Gram-negative bacteria secrete outer membrane vesicles (OMVs) that play critical roles in intraspecies, interspecies, and bacteria-environment interactions. Some OMVs, such as those produced by Pseudomonas aeruginosa, have previously been shown to possess antimicrobial activity against competitor species. In the current study, we demonstrate that OMVs from Burkholderia thailandensis inhibit the growth of drug-sensitive and drug-resistant bacteria and fungi. We show that a number of antimicrobial compounds, including peptidoglycan hydrolases, 4-hydroxy-3-methyl-2-(2-non-enyl)-quinoline (HMNQ) and long-chain rhamnolipid are present in or tightly associate with B. thailandensis OMVs. Furthermore, we demonstrate that HMNQ and rhamnolipid possess antimicrobial and antibiofilm properties against methicillin-resistant Staphylococcus aureus (MRSA). These findings indicate that B. thailandensis secretes antimicrobial OMVs that may impart a survival advantage by eliminating competition. In addition, bacterial OMVs may represent an untapped resource of novel therapeutics effective against bio-film-forming and multidrug-resistant organisms.

2.
J Drug Target ; 24(2): 169-77, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26211366

RESUMO

BACKGROUND: Human pancreatic carcinoids, a type of neuroendocrine tumors, are asymptomatic and difficult to diagnose, with the effects of traditional anti-cancer therapies being limited. The histone deacetylase (HDAC) inhibitor valproic acid (VPA) was evaluated for its effects alone and in combination with receptor-targeting peptide-drug conjugate via increasing drug internalization. MATERIALS AND METHODS: The in vitro and in vivo assays were used to evaluate the effects of VPA and somatostatin receptor-targeting camptothecin-somatostatin conjugate (CPT-SST). RESULTS: VPA induced proliferation suppression, cell apoptosis and cell cycle arrest. VPA acts as a HDAC inhibitor to induce a decrease of HDAC4 and an increase of acetylated histone 4 (AcH4). Meanwhile, most importantly, besides activating Notch signaling, VPA was observed to stimulate the expression of somatostatin receptor type 2 (SSTR2) that has been applied for receptor-targeting therapies. This characteristic was used for a combination therapy of VPA and CPT-SST. The combination displayed much more potent anti-tumor effects on carcinoid tumor growth by increasing SSTR2 density and drug internalization in target tumor cells. CONCLUSION: The combination of VPA and a SSTR2-targeting agent provides us a promising approach in treatment of carcinoid tumors.


Assuntos
Proliferação de Células/efeitos dos fármacos , Peptídeos/metabolismo , Receptores de Peptídeos/metabolismo , Receptores de Somatostatina/metabolismo , Ácido Valproico/farmacologia , Animais , Apoptose/efeitos dos fármacos , Camptotecina/farmacologia , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Inibidores de Histona Desacetilases/farmacologia , Histona Desacetilases/metabolismo , Histonas/metabolismo , Humanos , Camundongos , Camundongos Nus , Tumores Neuroendócrinos/tratamento farmacológico , Tumores Neuroendócrinos/metabolismo , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/metabolismo , Receptores Notch/metabolismo , Proteínas Repressoras/metabolismo , Transdução de Sinais/efeitos dos fármacos
3.
Arch Gynecol Obstet ; 288(2): 393-400, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23435724

RESUMO

PURPOSE: We investigated the effects of the anti-epilepsy drug valproic acid (VPA) alone and in combination in treating cervical cancer. METHODS: VPA was investigated for its effects on cervical cancer Hela cell proliferation and tumor growth via in vitro and in vivo assays. RESULTS: VPA induce cell growth suppression and cell cycle arrest, with an increase of Notch1 that acts as a tumor suppressor and the change of other tumor-associated genes such as p21, p63 and PCNA. VPA was also found to induce cell morphological change, with an increase of certain cell transformation markers such as snail1, snail2 and N-cadherin. Moreover, VPA could significantly up-regulate somatostatin receptor type II (SSTR2). Our in vivo study further demonstrated that VPA via inducing SSTR2 up-regulation extremely enhanced the anti-tumor ability of the SSTR2-preferential cytotoxic COL-SST conjugate in xenografts. CONCLUSIONS: VPA could not only suppress tumor progression but also provide a novel promising therapeutic choice in combination with a receptor-targeted cytotoxic conjugate via activating the specific receptor.


Assuntos
Anticonvulsivantes/farmacologia , Carcinoma/tratamento farmacológico , Receptor Notch1/metabolismo , Receptores de Somatostatina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Ácido Valproico/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Colchicina/uso terapêutico , Inibidor de Quinase Dependente de Ciclina p21/genética , Ciclo-Oxigenase 2/metabolismo , Combinação de Medicamentos , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Expressão Gênica , Genes p53/efeitos dos fármacos , Células HeLa , Hormônios/uso terapêutico , Humanos , Proteínas de Membrana/genética , Camundongos , Camundongos Nus , PTEN Fosfo-Hidrolase/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , RNA Mensageiro/metabolismo , Receptor Notch1/genética , Somatostatina/uso terapêutico , Moduladores de Tubulina/uso terapêutico
4.
Oncologist ; 17(2): 220-32, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22291092

RESUMO

The role of Notch signaling in cervical cancer is seemingly controversial. To confirm the function of Notch signaling in this type of cancer, we established a stable Notch1-activated cervical cancer HeLa cell line. We found that Notch1 activation resulted in apoptosis, cell cycle arrest, and tumor suppression. At the molecular level, we found that a variety of genes associated with cyclic AMP, G protein-coupled receptor, and cancer signaling pathways contributed to Notch1-mediated tumor suppression. We observed that the expression of somatostatin (SST) was dramatically induced by Notch1 signaling activation, which was accompanied by enhanced expression of the cognate SST receptor subtype 1 (SSTR1) and SSTR2. Certain genes, such as tumor protein 63 (TP63, p63), were upregulated, whereas others, such as B-cell lymphoma 2 (BCL-2), Myc, Akt, and STAT3, were downregulated. Subsequently, knockdown of Notch1-induced SST reversed Notch1-induced decrease of BCL-2 and increase of p63, indicating that Notch1-induced tumor suppression may be partly through upregulating SST signaling. Our findings support a possible crosstalk between Notch signaling and SST signaling. Moreover, Notch-induced SSTR activation could enhance SSTR-targeted cancer chemotherapy. Valproic acid (VPA), a histone deacetylase inhibitor, suppressed cell growth and upregulated the expression of Notch1 and SSTR2. A combination therapy with VPA and the SSTR2-targeting cytotoxic conjugate CPT-SST strongly led to greater suppression, as compared to each alone. Our findings thus provide us with a promising clinical opportunity for enhanced cancer therapy using combinations of Notch1-activating agents and SSTR2-targeting agents.


Assuntos
Receptor Notch1/fisiologia , Receptores de Somatostatina/fisiologia , Transdução de Sinais/fisiologia , Somatostatina/fisiologia , Neoplasias do Colo do Útero/prevenção & controle , Animais , Pontos de Checagem do Ciclo Celular , Proliferação de Células , Colforsina/farmacologia , AMP Cíclico/metabolismo , Feminino , Células HeLa , Humanos , Camundongos , Receptores de Somatostatina/antagonistas & inibidores , Neoplasias do Colo do Útero/patologia
5.
Amino Acids ; 42(5): 1727-33, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-21431932

RESUMO

A more convenient and facile approach for the synthesis and production of camptothecin-amino acids carbamate linkers, that can be used in the synthesis of bioconjugate peptides JF-10-81, JF-10-71, and other peptide analogs designed to target somatostatin receptors has been described.


Assuntos
Aminoácidos/química , Camptotecina/química , Carbamatos/química , Peptídeos/síntese química , Pró-Fármacos/síntese química , Técnicas de Síntese em Fase Sólida
6.
J Drug Target ; 19(8): 666-74, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21083509

RESUMO

In our previous study, we found that several tumor cell lines displayed high receptor-specific binding affinity, one of which, the human pancreatic carcinoid BON cell line, demonstrates high affinity binding of the bombesin (BN) and somatostatin (SST) receptor-specific ligands. In the present study, BON cells, as a representative model, were further applied to evaluate various peptide analogs and cytotoxic receptor-targeted peptide conjugates. We observed quick ligand-receptor internalization in BON cells as well as high binding affinity. Furthermore, BON cells have high expression of multidrug resistance-associated genes (MDR1) and show camptothecin (CPT) resistance. Various receptor-specific cytotoxic conjugates were synthesized and evaluated in the BON cell model via in vitro and in vivo studies. We found that all the tested conjugates displayed potent antitumor ability in xenografts. Especially, the CPT conjugates, CPT-SST, and CPT-BN, are most likely to increase sensitivity to CPT-resistant BON cells. Our findings suggest that appropriately defined tumor cell lines may provide physiologically relevant cell-based evaluations of novel peptide analogs and receptor-targeted chemotherapeutics.


Assuntos
Antineoplásicos Fitogênicos/administração & dosagem , Bombesina/química , Portadores de Fármacos/química , Desenho de Fármacos , Neoplasias Pancreáticas/metabolismo , Receptores de Superfície Celular/metabolismo , Somatostatina/química , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Animais , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/uso terapêutico , Bibenzilas/administração & dosagem , Bibenzilas/química , Bibenzilas/uso terapêutico , Camptotecina/administração & dosagem , Camptotecina/química , Camptotecina/uso terapêutico , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Humanos , Ligantes , Camundongos , Camundongos Nus , Terapia de Alvo Molecular , Ligação Proteica , Reação em Cadeia da Polimerase em Tempo Real , Receptores da Bombesina/metabolismo , Receptores de Somatostatina/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
7.
Clin Med Oncol ; 2: 491-9, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-21892324

RESUMO

The major problems of traditional chemotherapy are non-selectivity and non-specificity, resulting in severe toxic side effects. Peptides are a new-generation of drug-delivery vector to increase efficacy of this therapy and avoid the resulting damage. The cytotoxic somatostatin (SST) conjugate JF-10-81 was developed by coupling camptothecin (CPT) to the N-terminus of a SST analog (JF-07-69) using an activated carbamate linker. This conjugate selectively targets somatostatin receptor subtype 2 (SSTR2) and also retains high binding affinity and rapid internalization as well as anti-proliferative activity towards various tumor cells. JF-10-81 was tested for its inhibitory activity against the growth of human tumors which included neuroblastoma (IMR32), pancreatic cancer (CFPAC-1), leukemia (MOLT-4), pancreatic carcinoid (BON) and prostate cancer (PC-3). Both SSTR2 mRNAs and proteins were detected in all these tumor cell lines. The conjugate displayed potent in vivo inhibitory activity, although some of the potency measured in in vitro experiments was lost. JF-10-81 was found to significantly inhibit growth of these SSTR-positive tumors, resulting in 87% tumor reduction in neuroblastoma IMR32 and 97% in leukemia MOLT-4 bearing animals, even inducing regression of CFPAC-1 tumors. SSTR-overexpressing BON tumors were unfortunately relatively CPT-insensitive in vitro, however, JF-10-81 again exhibited in vivo potency presumably by specifically increasing CPT concentrations inside the tumor cells so that the inhibition rate for JF-10-81 was 85%. Also, JF-10-81 was used to treat highly invasive PC-3 tumors where s.c. injections inhibited both tumor growth (almost 60% reduction) and tumor metastasis (over 70%). This conjugate demonstrated its broad and excellent anti-tumor activity by targeting SSTR2-specific tumor tissues, supporting that short peptides and their analogs may be applied as ideal drug-delivery carriers to improve the traditional chemotherapy.

8.
Peptides ; 28(9): 1883-90, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17580098

RESUMO

The effects of vasoactive intestinal peptide-camptothecin (VIP-CPT) conjugates were investigated on breast cancer cells and cells transfected with VIP receptors (R). (Ala(2,8,9,19,24.25.27), Nle(17), Lys(28))VIP, (A-NL-K)VIP, was synthesized and Lys(28) was coupled to a linker, N-methyl-amino-ethyl-glycine, L2, which formed a carbamate bond with CPT. The resulting (A-NL-K)VIP-L2-CPT was cytotoxic for MCF7 breast cancer cells, which have VPAC(1)-R, with IC(50) values of 380 and 90 nM using the MTT and clonogenic assays, respectively. (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT inhibited specific binding of (125)I-VIP to 3T3 cells transfected with VPAC(1)-R with IC(50) values of 1.9, 56 and 126 nM, respectively. In contrast, (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT inhibited specific binding of (125)I-Ro25-1553 to 3T3 cells transfected with VPAC(2)-R with IC(50) values of 3.9, 3162 and 2690 nM, respectively. (A-NL-K)VIP, (A-NL-K)VIP-L2 and (A-NL-K)VIP-L2-CPT caused increased cAMP after addition to MCF7 cells. (125)I-(A-NL-K)VIP-L2-CPT was internalized by MCF7 cells at 37 degrees C but not 4 degrees C. These results indicate that (A-NL-K)VIP-L2-CPT is a VPAC(1)-R agonist which is cytotoxic for breast cancer cells.


Assuntos
Camptotecina/farmacologia , Proliferação de Células/efeitos dos fármacos , Peptídeo Intestinal Vasoativo/farmacologia , Células 3T3 , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Camptotecina/síntese química , Camptotecina/química , Linhagem Celular , Linhagem Celular Tumoral , AMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Humanos , Camundongos , Peptídeo Intestinal Vasoativo/síntese química , Peptídeo Intestinal Vasoativo/química
9.
Anticancer Drugs ; 18(3): 341-8, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17264768

RESUMO

The camptothecin-bombesin conjugate termed DC-51-43, as a novel targeted drug delivery system, was examined in over 10 human tumor cell lines and shows a potent antiproliferative activity. This conjugate has also demonstrated its antitumor activity in our previous experiments. In our present study, we evaluate this conjugate for its antiangiogenic activity by in-vitro and in-vivo experiments. The camptothecin-bombesin conjugate and free camptothecin show potent in-vitro inhibitory activities of cell adhesion to various extracellular matrix components and integrins alphaVbeta3 and alphaVbeta5, not beta1/alphabeta1. This conjugate displays inhibitory activity to cell migration and invasion at concentrations of 10 micromol/l or above. This conjugate is also effective against in-vitro capillary-like tube formation of endothelial cells (at 40 micromol/l), and in-vivo angiogenesis as seen by blocking the spread of host mice endothelial cells into matrigel plugs. These experimental results support the fact that the camptothecin-bombesin conjugate has therapeutic activities against angiogenesis. By binding to bombesin receptor-expressing sites, this bombesin analog, consisting of 11 amino acids, is potentially a novel delivery vector for nonspecific cytotoxic agents.


Assuntos
Inibidores da Angiogênese , Antineoplásicos Fitogênicos/farmacologia , Bombesina/análogos & derivados , Bombesina/farmacologia , Camptotecina/farmacologia , Adesão Celular , Linhagem Celular , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Ensaios de Seleção de Medicamentos Antitumorais , Citometria de Fluxo , Fase G1/efeitos dos fármacos , Humanos , Integrinas/metabolismo , Invasividade Neoplásica/patologia , Fase de Repouso do Ciclo Celular/efeitos dos fármacos
10.
Cancer Lett ; 246(1-2): 157-66, 2007 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-16644105

RESUMO

Camptothecin (CPT) was conjugated to the N-terminal of a somatostatin analog (SSA) directly via a carbamate group and a basic N-terminal linking motif, D-Lys-D-Tyr-Lys-D-Tyr-D-Lys. This new CPT-SSA conjugate termed JF-10-81 was evaluated as a receptor-specific delivery system for its anti-invasive and anti-angiogenic activities. It was found that, in addition to blocking migration and invasion of highly invasive prostate cancer PC-3 cells, this conjugate also inhibited in vitro capillary-like tube formation of endothelial cells and in vivo angiogenesis in C57B1/6N female mice. JF-10-81 was found to block PC-3 cell attachment to various extracellular matrix components, mainly to vitronectin, the ligand of cell surface receptors integrin alphaVbeta3 and alphaVbeta5. Additionally, JF-10-81 reduced expression of integrins alphaVbeta3 and alphaVbeta5 on PC-3 cell surfaces, without effects on beta1 or any alphabeta1 heterodimers. This conjugate also inactivated phosphorylation of protein kinase B (PKB/Akt), down-regulated the expression of latent matrix metalloproteinase (MMP) -2 and MMP-9, but had little effect on MMP-3/-10. Meanwhile, membrane type-1 matrix metalloproteinase (MT1-MMP) and the tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) were not detectable in PC-3 cells. alphaVbeta3/alphaVbeta5 and MMP-2/-9 are known to be highly expressed in many tumor cells and play an important role in tumor progression. Our results support that this conjugate could possibly inhibit prostate cancer PC-3 cell invasion through a signaling pathway involving PI3K/Akt, alphaVbeta3/alphaVbeta5 and MMP-2/-9, and this SSA could be used as an efficient vector to deliver CPT or other cytotoxic agents to target sites for cancer therapy.


Assuntos
Antineoplásicos/farmacologia , Camptotecina/farmacologia , Movimento Celular/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Somatostatina/farmacologia , Sequência de Aminoácidos , Animais , Antineoplásicos/química , Antineoplásicos/uso terapêutico , Western Blotting , Camptotecina/química , Camptotecina/uso terapêutico , Adesão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Feminino , Humanos , Integrina alfaVbeta3/metabolismo , Integrinas/metabolismo , Masculino , Metaloproteinase 2 da Matriz/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Invasividade Neoplásica , Neovascularização Patológica/patologia , Neovascularização Patológica/prevenção & controle , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Neoplasias da Próstata/fisiopatologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptores de Vitronectina/metabolismo , Somatostatina/química , Somatostatina/uso terapêutico
11.
J Pharmacol Exp Ther ; 318(3): 1265-72, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16766720

RESUMO

Most human tumors overexpress or ectopically express peptide hormone/neurotransmitter receptors, which are being increasingly studied as a means to selectively deliver cytotoxic agents. Although a number of peptide ligand-constructs demonstrate tumor cytotoxicity, the role of specific tumoral receptor interaction in its mediation is unclear. To address this question, we synthesized camptothecin (CPT) bombesin (Bn) analogs, in which CPT was coupled via a novel carbamate linker, L2 [N-(N-methyl-amino-ethyl)-glycine carbamate], that were chemically similar but differed markedly in their potency/affinity for human Bn receptors. We then examined their ability to interact with Bn receptors and cause in vitro and in vivo tumor cytotoxicity. CPT-L2-[D-Tyr(6),beta-Ala(11),D-Phe(13),Nle(14)] Bn (6-14) (BA3) bound with high affinity and had high potency for all three human Bn receptor subtypes, whereas CPT-L2-[D-Tyr(6),beta-Ala(11), D-Phe(13),Nle(14)] Bn (6-14) [D-Phe-CPT-L2-BA3] had >1400-fold lower affinity/potency. (125)I-CPT-L2-BA3 but not (125)I-D-Phe-CPT-L2-BA3 was internalized by Bn receptor subtype-containing cells. CPT-L2-BA3 displayed significantly more cytotoxicity than D-Phe-CPT-L2-BA3 toward NCI-H1299 lung cancer cells in both 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide and clonogenic assays and more potently inhibited H1299 xenograft growth in nude mice. CPT-L2-BA3 was also metabolically more stable than its parent peptide and inhibited growth of a number of other tumor cell lines in vitro and in vivo. These results demonstrate that specific tumoral receptor interaction is important in mediating the ability of peptide ligand-cytotoxic constructs to cause cytotoxicity. Because many tumors overexpress Bn receptors, these results also demonstrate that CPT-L2-BA3 will be a useful agent for delivering receptor-mediated cytotoxicity to many different human tumors.


Assuntos
Antineoplásicos/farmacologia , Bombesina/farmacologia , Camptotecina/farmacologia , Receptores da Bombesina/efeitos dos fármacos , Animais , Células 3T3 BALB , Bombesina/metabolismo , Camptotecina/metabolismo , Proliferação de Células/efeitos dos fármacos , Estabilidade de Medicamentos , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , Neoplasias Experimentais/tratamento farmacológico
12.
Retina ; 25(3): 345-54, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15805913

RESUMO

PURPOSE: To evaluate the ocular toxicity and efficacy of intravitreal camptothecin-somatostatin conjugate (JF-10-81), a somatostatin type 2 receptor-directed, antiangiogenic compound. METHODS: Part 1: New Zealand albino rabbits (except for controls) were injected intravitreally with conjugate at various concentrations. Preoperative and postoperative ocular examinations and electroretinography were performed until animals were killed for histology. Part 2: Long-Evans pigmented rats had choroidal neovascularization (CNV) induced by argon laser. One eye per animal was injected with concentration 10M (safe dose), whereas the other eyes were controls and received 30 microL of sterile water at different time intervals after laser application. Fluorescein angiography was performed at various time points to evaluate the lesions and confirm presence of CNV. Animals were euthanized. The eyes were immediately enucleated and prepared for histologic examination. RESULTS: Part 1: No clinical changes were seen in groups receiving 10(-8)M, 10(-7)M, 10(-6)M, and 10(-5) M of conjugate. Electroretinography showed decreasing b-wave amplitude in groups receiving 10(-4) M and 10(-3) M; cataracts also developed in these eyes. Part 2: Fluorescein angiography revealed that intravitreal injection of somatostatin conjugate JF-10-81 favorably affected the development of CNV when the treatment was performed at least 1 week after the laser application. These results were statistically significant. Histologic analysis results of eyes treated 2 weeks after laser application also showed significant benefit. CONCLUSIONS: Part 1: Camptothecin-somatostatin conjugate injected intravitreally appeared safe at concentrations of 10(-5)M or less. Part 2: Conjugate JF-10-81 at a concentration of 10(-5)M administered intravitreally 1 to 3 weeks after laser demonstrated statistically significant efficacy in the treatment of choroidal neovascularization.


Assuntos
Inibidores da Angiogênese/uso terapêutico , Camptotecina/uso terapêutico , Neovascularização de Coroide/tratamento farmacológico , Somatostatina/uso terapêutico , Animais , Camptotecina/toxicidade , Neovascularização de Coroide/fisiopatologia , Modelos Animais de Doenças , Quimioterapia Combinada , Eletrorretinografia , Angiofluoresceinografia , Injeções , Terapia a Laser , Masculino , Coelhos , Ratos , Ratos Long-Evans , Retina/efeitos dos fármacos , Retina/fisiopatologia , Somatostatina/toxicidade , Corpo Vítreo
13.
Drug Deliv ; 11(4): 231-8, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15371104

RESUMO

Two CPT-SSA conjugates, JF-10-71 and JF-10-81, containing a chemically adjustable release-rate carbamate linker, have been reported previously by us to potently inhibit growth of human neuroblastoma IMR32 cells overexpressing somatostatin receptor type II (SSTR2) but are stable under buffer incubation conditions or in rat plasma. Further experiments now reveal that the conjugates performed well against many additional cell lines, particularly somatostatin receptor containing rat pancreatic CA20948 cells that were actually more sensitive to the conjugates than free camptothecin itself. JF-10-71 and JF-10-81 also were examined for their inhibitory effects on the growth of this and several other tumors transplanted into rats (CA20948) or nude mice. CA20948 tumors, known to overexpress SSTR2 and grown in Lewis rats, were treated, respectively, with nontoxic 400 nmol/kg intraperitoneal (i.p.) doses of JF-10-71 or JF-10-81. Also, SSTR2-positive human SCLC NCI-H69 tumors transplanted in nude mice were treated in a similar fashion. Human prostate PC-3 tumors, which do not contain high concentrations of SSTR2, also were grown in nude mice and treated with a 400 nmol/kg ip dose of JF-10-71. Both cytotoxic conjugates significantly inhibited growth of SSTR2-specific pancreatic and SCLC tumors, but JF-10-81 did not significantly affect PC-3 tumor growth. These experimental results suggested that CPT-SSA conjugates can effectively target and kill tumor cells growing in vivo and that the effect is mediated by somatostatin receptors resulting in either release of camptothecin at the cell surface or, more likely, after receptor-mediated cellular internalization.


Assuntos
Antineoplásicos/administração & dosagem , Camptotecina/administração & dosagem , Inibidores do Crescimento/administração & dosagem , Somatostatina/administração & dosagem , Animais , Antineoplásicos/química , Camptotecina/química , Linhagem Celular Tumoral , Inibidores do Crescimento/química , Humanos , Camundongos , Camundongos Nus , Ratos , Ratos Endogâmicos Lew , Somatostatina/química , Ensaios Antitumorais Modelo de Xenoenxerto/métodos
14.
J Surg Res ; 119(1): 1-13, 2004 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-15126075

RESUMO

BACKGROUND: Creation of protease-resistant somatostatin analogs has allowed development of these peptides as clinically useful drugs. Widespread diagnostic use of radiolabeled somatostatin analogs has enhanced interest in the binding and intracellular distribution of these peptides. The degree of drug internalization and length of drug retention may be critical for drug-induced cytotoxicity. We hypothesized that the ability of a radiolabeled peptide to bind to a cell, be internalized, and induce cytotoxicity is proportional to both the radioligand concentration and the exposure time. MATERIALS AND METHODS: To test this hypothesis, somatostatin receptor-expressing cells (IMR-32) were incubated with (111)In-pentetreotide, a sst 2 preferring somatostatin analogue. Radioligand exposure time and/or concentration were varied. RESULTS: Prolonged exposure to a fixed concentration of radioligand resulted in progressive increases in whole cell binding and internalization over time. Cells exposed to a relatively fixed number of microCi-Hr yielded constant whole cell binding and internalization. Increasing the microCi-Hr resulted in a proportionate increase in binding. Cytotoxicity was also proportional to the dose of radiation regardless of whether the exposure was internalized radiation (microCi-Hr from (111)In-pentetreotide) or from external beam radiation (cGy). CONCLUSION: Both drug exposure time and drug concentration contribute to cell binding and cytotoxicity in this model and their relative contributions are inversely related.


Assuntos
Somatostatina/análogos & derivados , Somatostatina/administração & dosagem , Somatostatina/metabolismo , Transporte Biológico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Humanos , Radioisótopos de Índio , Concentração Osmolar , Ensaio Radioligante , Somatostatina/farmacocinética , Fatores de Tempo
15.
Bioorg Med Chem Lett ; 14(9): 2041-6, 2004 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-15080975

RESUMO

A series of novel 1,4-diaryl-2-azetidinones was prepared by stereospecific Staudinger reaction as conformationally restricted analogues of combretastatin A-4 because molecular modeling studies suggested close geometric similarities. They were evaluated for cytotoxicity against a number of human tumor and normal cell lines. Strong potencies were observed, with the best compounds exhibiting IC(50)'s of 25-74 nM against human neuroblastoma IMR 32 cell growth and a variety of other cell lines. Compounds inhibited tubulin polymerization with potencies commensurate with their cytotoxic activity and a more soluble anilino-containing analogue was very effective in inhibiting the growth of AR42J rat pancreatic tumors transplanted into in nude mice. Further studies on this interesting group of compounds as anti-cancer agents appear warranted.


Assuntos
Antineoplásicos/química , Azetidinas/química , Estilbenos/química , Animais , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Humanos , Camundongos , Camundongos Nus , Modelos Moleculares , Ratos , Estilbenos/síntese química , Estilbenos/farmacologia
16.
Anticancer Res ; 24(1): 179-86, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15015595

RESUMO

BACKGROUND: Combretastatin A-4 (CA-4) and its analogs are potent inhibitors of tubulin polymerization and display strong inhibitory activity on both solid tumor and tumor cell growth. Since natural CA-4 is difficult to synthesize and also isomerizes to an inactive form quite readily, a recently reported new 3,4-diarylfuran-2-one-based series of CA-4 analogs was investigated, in the hope of bypassing some of these difficulties. These analogs appear to offer a valuable tool for CA-4 research because of their extremely facile synthesis from readily available starting materials. MATERIALS AND METHODS: The CA-4 analogs were evaluated by MTT assay, cell cycle analysis, tubulin polymerization and tumor-inhibiting experiments. RESULTS: Various benzene ring substitutions on the furan-2-one skeleton (analogs to the two aromatic rings on the CA-4 styrene skeleton) quickly demonstrated that the structure-activity relationships are quite similar to previously synthesized CA-4 analogs. The most interesting analog appears to be an anilino compound (NV-5-9) which was also quite soluble. Analog NV-5-9 was remarkably potent in all tested tumor cell lines and could strongly inhibit tubulin polymerization at doses as low as 1 mM. Further experiments with tumor-bearing mice indicated that NV-5-9 and other potent analogs (NV-4-82 and NV-4-86) were effective in treating human prostate PC-3 and SCLC NCI-H69 tumors at well below an oral MTD dose of around 200 mg/kg body weight. This suggests some bioavailability by this route. CONCLUSION: These data strongly support that NV-5-9 is extremely potent, readily synthesizable and apparently suitable for in vivo studies employing transplanted tumors.


Assuntos
Antineoplásicos Fitogênicos/farmacologia , Furanos/farmacologia , Estilbenos/farmacologia , Animais , Antineoplásicos Fitogênicos/toxicidade , Ciclo Celular/efeitos dos fármacos , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Furanos/toxicidade , Inibidores do Crescimento/farmacologia , Inibidores do Crescimento/toxicidade , Humanos , Masculino , Camundongos , Camundongos Nus , Estilbenos/toxicidade , Tubulina (Proteína)/metabolismo , Ensaios Antitumorais Modelo de Xenoenxerto
17.
Bioorg Med Chem Lett ; 13(5): 799-803, 2003 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-12617894

RESUMO

Peptide hormones are often rapidly internalized after binding to and activation of their receptors which are sometimes over-expressed on tumor cells. Thus, peptide ligands are increasingly being utilized for specific tumor cell targeting and internalization of radioactive isotopes for tumor imaging and for specifically delivering and internalizing cytotoxic moieties. Here, we describe a new carbamate linker system containing a series of built-in nucleophile assisted releasing (BINAR) groups which enable the 'fine-tuning' of intracellular cleavage rates of free cytotoxic agents containing reactive OH groups. Release rates were found to fit well with the chemical model and several conjugates of camptothecin and one of combretastatin were shown to have potent cytotoxic effects on cultures of human neuroblastoma IMR-32 cells which over-express somatostatin receptors.


Assuntos
Antineoplásicos/química , Carbamatos/química , Reagentes para Ligações Cruzadas/química , Peptídeos/química , Estilbenos , Sequência de Aminoácidos , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Bibenzilas/química , Bibenzilas/farmacocinética , Bibenzilas/farmacologia , Camptotecina/química , Camptotecina/farmacocinética , Camptotecina/farmacologia , Carbamatos/farmacologia , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Concentração Inibidora 50 , Neuroblastoma/tratamento farmacológico , Neuroblastoma/metabolismo , Peptídeos/administração & dosagem , Ratos , Somatostatina/análogos & derivados , Relação Estrutura-Atividade , Células Tumorais Cultivadas
18.
Peptides ; 23(9): 1557-65, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12217415

RESUMO

Peptide nucleic acid (PNA) sequences are synthetic versions of naturally occurring oligonucleotides which display improved binding properties to DNA and RNA, but are still poorly internalized across cell membranes. In an effort to employ the rapid binding/internalization properties of somatostatin agonist analogs and the over-expression of somatostatin receptors on many types of tumor cells, PNAs complementary to target sites throughout 5'-UTR, translation start site and coding region of the n-myc oncogene were conjugated to a somatostatin analog (SSA) with retention of high somatostatin biological potency. IMR32 cells, which over-express somatostatin receptor type 2 (SSTR2) and contain the n-myc oncogene, were treated with these PNA-SSA conjugates. The results show that PNA conjugates targeted to the 5'-UTR terminus and to regions at or close to the translation start site could effectively inhibit n-myc gene expression and cell growth, whereas the non-conjugate PNAs were without effect at similar doses. The most potent inhibition of cell growth was achieved with PNAs binding to the translation start site, but those complementary to the middle coding region or middle upstream site between 5'-UTR and translation start site displayed no inhibition of gene expression. These observations were extended to four other cell lines: GH3 cells which express SSTRs with the n-myc gene, SKNSH cells containing a silent n-myc gene without SSTR2, HT-29 cells carrying the c-myc but no n-myc gene, and CHO-K1 cells lacking SSTR2 with n-myc gene. The results show that there was almost no effect on these four cell lines. Our study indicates that PNAs conjugated to SSA exhibited improved inhibition of gene expression possibly due to facilitated cellular uptake of the PNAs. These conjugates were mRNA sequence- and SSTR2-specific suggesting that many other genes associated with tumor growth could be targeted using this approach and that SSA could be a novel and effective transportation vector for the PNA antisense strategy.


Assuntos
Oligonucleotídeos Antissenso/farmacologia , Proteínas Proto-Oncogênicas c-myc/metabolismo , Receptores de Somatostatina/metabolismo , Somatostatina/análogos & derivados , Regiões 5' não Traduzidas , Animais , Sequência de Bases , Western Blotting , Divisão Celular , Corantes/farmacologia , Hormônio do Crescimento/metabolismo , Humanos , Concentração Inibidora 50 , Masculino , Modelos Químicos , Dados de Sequência Molecular , Ácidos Nucleicos Peptídicos/metabolismo , RNA Mensageiro/metabolismo , Ratos , Sais de Tetrazólio/farmacologia , Tiazóis/farmacologia , Células Tumorais Cultivadas
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