Biomedical subjects

Gordon R Macpherson

Publications and source records attributed to Gordon R Macpherson.

9 recordsLinked to original sources

PubMed2006

Evaluation of human fetal bone implants in SCID mice as a model of prostate cancer bone metastasis.

The metastasis of prostate cancer cells to the bone marrow constitutes the major source of morbidity and mortality in prostate cancer. Studying this process has been hampered by the lack of preclinical models to evaluate novel therapeutics and to study the biology of the disease. One proposed model utilizes human fetal bone implants to serve as the target for prostate cancer cells injected via the tail vein. We employed this model to test the ability of zoledronic acid to prophylax and to treat bone metastases. To improve the rate of bone metastasis, we used two bone implants instead of one to evaluate the cell lines PC3 and PC3M, a more metastatic subline. For this purpose we generated the novel cell line PC3EGFPLuc, which can be used for luminescence and/or fluorescence imaging in vivo. We did not observe bone implant metastases in 52 mice, with 90 bone implants following tail vein injection of 1x10(6) PC3 or PC3M cells. Soft tissue lesions in the buttocks and hind limbs as well as cellular growth in the hindlimbs were observed via bioluminescence imaging. This evidence together with literature findings suggests that this model produces artifactual 'bone metastasis' lesions.

Animals↗

PubMed2004

Genotyping and functional analysis of the D104N variant of human endostatin.

Endostatin is an endogenous inhibitor of angiogenesis derived from the extracellular matrix protein collagen XVIII. It has been reported that a variation at the 104 position (D104N) of human endostatin is associated with an increased risk of prostate cancer, potentially indicating that this protein variant is less active as an anti-angiogenic agent. Herein we reported the results of genotyping 389 patients with androgen independent prostate cancer (AIPC) and 352 normal control individuals for D104N endostatin. There was no significant association between the frequency of 104N endostatin and the incidence of AIPC in either Caucasian or African American patients compared to controls (15% Caucasian AIPC versus 13.7% in Caucasian controls, p=0.79; 7.4% African American AIPC versus 5.6% in African American controls, p=0.64). Actuarial analysis revealed no statistically significant association between incidence of the DN heterozygous genotype and survival (p=0.62 by logrank test). To study the functional significance of the D104N conversion, we have expressed and purified insoluble recombinant human 104D and 104N endostatin and compared their respective activities in human umbilical vein endothelial cell (HUVEC) tube formation assays. The 104N variant of human endostatin inhibited HUVEC tube formation at least as well as the wild-type form. We concluded that the D104N variation in human endostatin is neither clinically relevant nor suitable as a pharmacogenomic endpoint to assess the risk for developing AIPC.

Aged↗

PubMed2004

Small molecule-mediated anti-cancer therapy via hypoxia-inducible factor-1 blockade.

Despite reservations regarding potential toxicities, small molecule-mediated blockade of the hypoxia-inducible factor-1 transcription factor has emerged as a viable anti-cancer strategy in vivo. Recent experiments by Welsh et al. revealed unprecedented anti-tumor responses of various aggressive solid tumors to the HIF-1-inhibitory small molecule drug PX-478. Compared with other anti-cancer drugs, PX-478 had markedly improved regression, growth delay and log10 cell kill profiles, particularly against large tumors that are normally refractory to small molecule drug therapy. Importantly, pharmacokinetic and toxicity profiles were within acceptable limits, providing rationale for the clinical development of HIF-1 inhibitors in general. Though the mechanism of action for PX-478 is not completely understood, inhibition of glycolysis rather than angiogenesis appeared to be the primary mode of anti-cancer activity.

Animals↗

PubMed2004

Thalidomide.

Despite its history as a human teratogen, thalidomide is emerging as a treatment for cancer and inflammatory diseases. Although the evolution of its clinical application could not have been predicted from the tragedy associated with its misuse in the past, its history serves as a lesson in drug development that underscores the need to understand the molecular pharmacology of a compound's activity, including associated toxicities. Here, we summarise the applications for thalidomide with an emphasis on clinical trials published over the past 10 years, and consider our knowledge of the molecular pharmacology of the drug in the context of clinical trial data, attempting to provide a mechanism-guided understanding of its activity.

Clinical Trials as Topic↗

PubMed2003

Current status of thalidomide and its role in the treatment of metastatic prostate cancer.

Following the discovery of its anti-angiogenic properties and despite its tragic history, thalidomide has re-surfaced in the field of oncology. Concurrent with its evaluation in various clinical trials for cancer, thalidomide's mechanism of action is sought and new analogues with improved efficacy and pharmacological profile are emerging. This review is a critical evaluation of thalidomide metabolism, molecular targets, anti-angiogenic activity and clinical efficacy with an emphasis on metastatic prostate cancer.

Angiogenesis Inhibitors↗

PubMed2003

Studies of the biosynthesis of DTX-5a and DTX-5b by the dinoflagellate Prorocentrum maculosum: regiospecificity of the putative Baeyer-Villigerase and insertion of a single amino acid in a polyketide chain.

The biosynthetic origins of the diarrhetic shellfish poisoning toxins DTX-5a and DTX-5b have been elucidated by supplementing cultures of the producing organism Prorocentrum maculosum with stable isotope labeled precursors and determining the incorporation patterns by 13C NMR spectroscopy. The amino acid residue in the sulfated side chain is found to originate from glycine, and oxygen insertion in the chain is shown to occur after polyketide formation.

Amino Acids↗

PubMed2003

New directions in cancer research 2003: technological advances in biology, drug resistance, and molecular pharmacology.

The 94th Annual Meeting of the American Association for Cancer Research (AACR) was held from July 11 to 14, 2003 in Washington, DC, and provided an overview of the latest developments in the field of cancer. This report provides highlights of presentations on array-based and RNA-interference technologies to study cancer biology and molecular pharmacology of anticancer drugs, mechanisms and modulation of drug resistance patterns, recent developments in the treatment of prostate cancer, and the medicinal chemistry of established and novel anticancer drugs.

American Cancer Society↗

PubMed2003

Anti-angiogenic activity of human endostatin is HIF-1-independent in vitro and sensitive to timing of treatment in a human saphenous vein assay.

Endostatin is a 20-kDa endogenous angiogenesis inhibitor that has recently been shown to inhibit the expression of vascular endothelial growth factor (VEGF), an angiogenic growth factor that is up-regulated by hypoxia via the HIF-1 transcription factor complex. To determine if the anti-angiogenic activity of endostatin involves a modulation of the HIF-1/VEGF pathway in cancer cells, experiments were conducted to establish what effect endostatin has on HIF-1 activity, HIF-1alpha protein production, and cellular localization in prostate cancer cells and endothelial cells. Endothelial cell tube formation was inhibited by endostatin purchased from Calbiochem (San Diego, CA) but not endostatin obtained from EntreMed (Rockville, MD). Subsequent experiments using Calbiochem endostatin showed that it did not alter HIF-1alpha protein production or cellular localization in any of the cell lines tested, nor did it alter HIF-1 transactivational activity in hypoxia. Whether or not this is also true in vivo remains to be determined. Nevertheless, these data suggest that the anti-angiogenic activity of endostatin is independent of the HIF-1/VEGF pathway. Immunocytochemical staining results do not indicate a decreased production of VEGF in Calbiochem endostatin-treated LNCaP or human umbilical vein endothelial cells (HUVEC). Treatment of rat aortic cross sections with human endostatin from Calbiochem resulted in a dose-dependent inhibition of microvessel outgrowth. Importantly, inhibition of vessel outgrowth by Calbiochem endostatin in a human saphenous vein angiogenesis assay required early treatment. In view of this in vitro data, we suggest that clinical trials involving endostatin treatment of late-stage disease may not adequately represent the efficacy of this drug in early-stage cancer.

Angiogenesis Inhibitors↗

PubMed2002

Antiangiogenesis therapeutic strategies in prostate cancer.

It is now well documented that tumor progression from its early stages to an advanced metastatic state requires the recruitment of new vasculature. The reliance on angiogenesis by tumors renders them susceptible to agents that can interfere with the angiogenic process. Recent interest in the therapeutic potential of using angiogenesis as a target mechanism for anticancer therapy has led to the identification of various antiangiogenic agents that interfere at various stages of the process. This review is a summary of recent progress in the identification and characterization of antiangiogenesis agents with a focus on their utility with respect to prostate cancer. Though we focus on prostate cancer, this knowledge is relevant to any cancer that involves angiogenesis.

Angiogenesis Inhibitors↗