ABSTRACT
Accumulating evidence has shown multiple roles that chemokine receptor CCR5 may play to promote the progression of several types of cancer. The mechanism of such promotion is believed to involve chronic inflammation that creates a microenvironment which enhances tumor survival. Therefore, blocking CCR5 function with an antagonist may provide a novel treatment of cancers such as prostate cancer. Currently, several CCR5 antagonists are available, but all have been optimized for their inhibitory activity on HIV-1 cellular membrane invasion process rather than inhibition on cytoplasmic signaling pathways. Thus, there is need to develop CCR5 antagonists focusing on blockage of CCR5 downstream signaling and inhibition of CCR5 related prostate cancer proliferation and progression. In this report, a pharmacophore analysis was conducted based on docking studies of several known CCR5 antagonists in a CCR5 homology model. A unique structural skeleton for CCR5 antagonist was constructed and functionalized, resulting in a new series of small molecules to be synthesized and characterized. A combination of CCR5 calcium flux inhibition, anti prostate cancer cell proliferation, basal cytotoxicity, and in vivo animal model studies were applied to screen the newly synthesized compounds. Results from this study provided a potential lead compound for future CCR5 antagonist development focusing on prostate cancer therapy.
Subject(s)
Antineoplastic Agents/pharmacology , CCR5 Receptor Antagonists , Drug Design , Prostatic Neoplasms/drug therapy , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/chemistry , Cell Line, Tumor , Cell Proliferation/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Humans , Male , Mice , Models, Molecular , Molecular Structure , NIH 3T3 Cells , Prostatic Neoplasms/pathology , Receptors, CCR5 , Structure-Activity RelationshipABSTRACT
Paclitaxel (Taxol)-induced cell death requires the intrinsic cell death pathway, but the specific participants and the precise mechanisms are poorly understood. Previous studies indicate that a BH3-only protein BIM (BCL-2 Interacting Mediator of cell death) plays a role in paclitaxel-induced apoptosis. We show here that BIM is dispensable in apoptosis with paclitaxel treatment using bim(-/-) MEFs (mouse embryonic fibroblasts), the bim(-/-) mouse breast tumor model, and shRNA-mediated down-regulation of BIM in human breast cancer cells. In contrast, both bak (-/-) MEFs and human breast cancer cells in which BAK was down-regulated by shRNA were more resistant to paclitaxel. However, paclitaxel sensitivity was not affected in bax(-/-) MEFs or in human breast cancer cells in which BAX was down-regulated, suggesting that paclitaxel-induced apoptosis is BAK-dependent, but BAX-independent. In human breast cancer cells, paclitaxel treatment resulted in MCL-1 degradation which was prevented by a proteasome inhibitor, MG132. A Cdk inhibitor, roscovitine, blocked paclitaxel-induced MCL-1 degradation and apoptosis, suggesting that Cdk activation at mitotic arrest could induce subsequent MCL-1 degradation in a proteasome-dependent manner. BAK was associated with MCL-1 in untreated cells and became activated in concert with loss of MCL-1 expression and its release from the complex. Our data suggest that BAK is the mediator of paclitaxel-induced apoptosis and could be an alternative target for overcoming paclitaxel resistance.
Subject(s)
Antineoplastic Agents/pharmacology , Apoptosis Regulatory Proteins/metabolism , Apoptosis/drug effects , Breast Neoplasms/pathology , Membrane Proteins/metabolism , Paclitaxel/pharmacology , Proto-Oncogene Proteins/metabolism , bcl-2 Homologous Antagonist-Killer Protein/metabolism , bcl-2-Associated X Protein/metabolism , Animals , Bcl-2-Like Protein 11 , Cell Line, Tumor , Female , Humans , Mice , Myeloid Cell Leukemia Sequence 1 Protein , Proto-Oncogene Proteins c-bcl-2/metabolism , RNA, Small Interfering/genetics , bcl-2 Homologous Antagonist-Killer Protein/deficiency , bcl-2 Homologous Antagonist-Killer Protein/geneticsABSTRACT
Recent studies have indicated that the CCR5 chemokine receptor may be a potential target for treating prostate cancer. Thus, development of CCR5 antagonists may provide novel prostate cancer therapy. Anibamine, a novel pyridine quaternary alkaloid isolated from Aniba sp., was found to effectively compete with (125)I-gp120 in binding to the chemokine receptor CCR5, with an IC(50) = 1 µM. Anibamine is the first natural product reported as a CCR5 antagonist, and thus provides a novel structural skeleton unique from other lead compounds that have generally been identified from high-throughput screening efforts. In order to refine the lead compound's structure and improve the therapeutic index of anibamine derivatives as potential anti prostate cancer agents, the approach of "deconstruction-reconstruction-elaboration" was applied in the structure-activity relationship studies of this work. Here, we report the design, syntheses and anti prostate cancer activities of anibamine and 17 analogues. The results from the in vitro and in vivo studies described here show that this class of compounds has potential to provide novel leads as anti prostate cancer agents.
Subject(s)
Biological Products/chemistry , Biological Products/pharmacology , CCR5 Receptor Antagonists , Drug Discovery , Prostatic Neoplasms/drug therapy , Pyridines/chemistry , Pyridines/pharmacology , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Biological Products/therapeutic use , Calcium/metabolism , Cell Line, Tumor , Cell Proliferation/drug effects , Chemokine CCL5/pharmacology , Humans , Male , Mice , NIH 3T3 Cells , Prostatic Neoplasms/pathology , Pyridines/therapeutic use , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
Accumulating evidence indicates that the chemokine receptor CCR5 and the chemokine CCL5 may be involved in the proliferation and metastasis of prostate cancer. Consequently, chemokine receptor CCR5 antagonists could potentially act as anti-prostate cancer agents. As the first natural product CCR5 antagonist, anibamine provides a novel chemical structural skeleton compared with other known antagonists identified through high-throughput screening. Our studies demonstrate that anibamine produces significant inhibition of prostate cancer cell proliferation at micromolar to submicromolar concentrations as well as suppressing adhesion and invasion of the highly metastatic M12 prostate cancer cell line. Preliminary in vivo studies indicate that anibamine also inhibits prostate tumor growth in mice. These findings indicate that anibamine may prove to be a novel lead compound for the development of prostate cancer therapeutic agents.
Subject(s)
Antineoplastic Agents/chemistry , CCR5 Receptor Antagonists , Prostatic Neoplasms/drug therapy , Pyridines/chemistry , Animals , Antineoplastic Agents/therapeutic use , Cell Line, Tumor , High-Throughput Screening Assays , Male , Mice , Prostatic Neoplasms/pathology , Pyridines/therapeutic use , Receptors, CCR5/metabolismABSTRACT
The use of kidneys from non-heart beating donors (NHBDs) presents a paradox; whilst they provide more organs for transplantation, there is an increased risk of poor graft outcome, particularly in the short term. This study has highlighted the difference in early graft function and late graft survival between NHBD kidneys with short (controlled) and long (uncontrolled) warm ischaemic times. Whilst it would seem that it is preferable to use controlled donors only, their numbers are small. By employing a rational approach to the use of each of these types of kidney, such as structured viability assessment and risk analysis, it may be that the results of uncontrolled NHBD can be improved.
