Targeted inhibition of mitochondrial Hsp90 suppresses localised and metastatic prostate cancer growth in a genetic mouse model of disease

BACKGROUND: The molecular chaperone heat shock protein-90 (Hsp90) is a promising cancer drug target, but current Hsp90-based therapy has so far shown limited activity in the clinic. METHODS: We tested the efficacy of a novel mitochondrial-targeted, small-molecule Hsp90 inhibitor, Gamitrinib (GA mitochondrial matrix inhibitor), in the Transgenic Adenocarcinoma of the Mouse Prostate (TRAMP) model. The TRAMP mice receiving 3-week or 5-week systemic treatment with Gamitrinib were evaluated for localised or metastatic prostate cancer, prostatic intraepithelial neoplasia (PIN) or localised inflammation using magnetic resonance imaging, histology and immunohistochemistry. Treatment safety was assessed histologically in organs collected at the end of treatment. The effect of Gamitrinib on mitochondrial dysfunction was studied in RM1 cells isolated from TRAMP tumours. RESULTS: Systemic administration of Gamitrinib to TRAMP mice inhibited the formation of localised prostate tumours of neuroendocrine or adenocarcinoma origin, as well as metastatic prostate cancer to abdominal lymph nodes and liver. The Gamitrinib treatment had no effect on PIN or prostatic inflammation, and caused no significant animal weight loss or organ toxicity. Mechanistically, Gamitrinib triggered acute mitochondrial dysfunction in RM1 cells, with loss of organelle inner membrane potential and release of cytochrome-c in the cytosol. CONCLUSIONS: The Gamitrinib has pre-clinical activity and favourable tolerability in a genetic model of localised and metastatic prostate cancer in immunocompetent mice. Selective targeting of mitochondrial Hsp90 could provide novel molecular therapy for patients with advanced prostate cancer

Biodiversity, traditional medicine and public health: where do they meet?

Given the increased use of traditional medicines, possibilities that would ensure its successful integration into a public health framework should be explored. This paper discusses some of the links between biodiversity and traditional medicine, and addresses their implications to public health. We explore the importance of biodiversity and ecosystem services to global and human health, the risks which human impacts on ecosystems and biodiversity present to human health and welfare

Derivation of MPR and TRAMP models of prostate cancer and prostate cancer metastasis for evaluation of therapeutic strategies

Pre-clinical models of primary and metastatic prostate cancer are increasingly needed to evaluate efficacy of the new therapeutic strategies currently under investigation. The androgen-independent RM1 and androgen-dependent TR cell lines derived from transgenic mouse models of prostate cancer were examined in this regard. Following implantation in immune competent mice, the RM1 cell line was able to generate extremely fast growing sc and iprost tumors and metastatic lung lesions providing a time period of approximately 14-17 days from the time of tumor establishment to animal sacrifice to assess therapies. Implantation of TR cell lines resulted in more slowly growing sc and iprost tumors and metastatic lung lesions that exhibited highly variable incidence and growth. These models represent the best available means to evaluate therapeutics in primary and metastatic prostate cancer variants in an intact immune system. © 2002 Elsevier Science Inc. All rights reserved

Purine nucleoside phosphorylase and fludarabine phosphate gene-directed enzyme prodrug therapy suppresses primary tumour growth and pseudo-metastases in a mouse model of prostate cancer

Gene-directed enzyme prodrug therapy based on the E. coli purine nucleoside phosphorylase (PNP) gene produces efficient tumour cell killing. PNP converts adenosine analogs into toxic metabolites that diffuse across cell membranes to kill neighbouring untransduced cells (PNP-GDEPT). Interference with DNA, RNA and protein synthesis kills dividing and non-dividing cells, an important consideration for slow-growing prostate tumours. This study examined the impact of administering PNP-GDEPT into orthotopically grown RM1 prostate cancers (PCas) on the growth of lung pseudo-metastases of immunocompetent mice. C57BL/6 mice bearing orthotopic RM1 PCas received a single intraprostatic injection of OAdV220 (1010 particles), a recombinant ovine atadenovirus containing the PNP gene controlled by the Rous Sarcoma virus promoter, followed by fludarabine phosphate (∼600 mg/m2/day) administered intraperitoneally (ip) once daily for 5 days. Pseudo-metastases were induced 2 days after intraprostatic vector administration by tail-vein injection of untransduced RM1 cells. Mice given PNP-GDEPT showed a significant reduction both in prostate volume (∼50%) and in lung colony counts (∼60%). Apoptosis was increased two-fold in GDEPT-treated prostates compared with controls (P < 0.01), but was absent in the lungs. Staining for proliferating cell nuclear antigen (PCNA) indicated that proliferation of both RM1 prostate tumours (P < 0.01) and lung colonies (P < 0.01) was significantly suppressed after GDEPT. Although prostate tumour immune cell infiltration did not differ significantly between treatments, immunostaining for Thy-1.2 (CD90) showed that GDEPT promoted Thy-1.2+ cell infiltration into the prostate tumour site. This study showed that a single course of PNP-GDEPT significantly suppressed local PCa growth and reduced lung colony formation in the aggressive RM1 tumour model. Copyright © 2004 John Wiley & Sons, Ltd

Gene-directed enzyme prodrug therapy for prostate cancer in a mouse model that imitates the development of human disease

Background. Gene-directed enzyme prodrug therapy (GDEPT) based on the E. coli enzyme purine nucleoside phosphorylase (PNP) represents a new approach for treating slow growing tumours like prostate cancer (PCa). Expressed enzyme converts a systemically administered prodrug, fludarabine phosphate, to a toxic metabolite, 2-fluoroadenine. Infected and neighbouring cells are killed by a bystander effect that results from the inhibition of DNA and RNA synthesis. Methods. These studies were carried out using the transgenic adenocarcinoma of the prostate (TRAMP) model that mimics human PCa development and progression. Control TRAMP mice were injected intraprostatically with vector vehicle and thereafter intraperitoneally with saline or fludarabine phosphate (∼600 mg/m2/day) once daily for 5 consecutive days. Treated mice received a single intraprostatic injection containing 1010 particles of OAdV220, an ovine atadenovirus which expresses the E. coli PNP gene under the control of the Rous sarcoma virus promoter, followed by systemic fludarabine treatment. The weight of the genitourinary tract, seminal vesicles and the prostate as well as animal survival were monitored. Tumours were also analysed histologically. Results. Preliminary studies showed that fludarabine alone caused no significant change in genitourinary (GU) tract weight in TRAMP mice. Animals injected with vector and prodrug showed a significant reduction (36-47%) in GU tract weight (ANOVA p = 0.0002) and a 35-50% reduction in seminal vesicle weight (ANOVA p = 0.0007). In particular, the target organ showed a significant 57% reduction in prostate weight (ANOVA p = 0.0007). PNP-GDEPT mice also showed a survival advantage over control mice. Histological analysis suggested that the cancer progression was slowed in GDEPT-treated animals. Conclusion. A single course of GDEPT based on OAdV-delivered PNP and fludarabine produced highly significant suppression of PCa progression in immune-competent TRAMP mice. Copyright © 2004 John Wiley & Sons, Ltd

What Determines Student Evaluation Scores? A Random Effects Analysis of Undergraduate Economics Classes

Student evaluation scores are a standard component of the way colleges and universities assess the quality of an instructor's teaching for purposes of promotion and tenure, as well as merit raise allocations. This paper applies a feasible generalized least squares model to a panel of data from undergraduate economics classes. We find that instructors can “buy” better evaluation scores by inflating students’ grade expectations. Class size and instructor experience are important determinants of evaluation scores in principles classes, but not in upper-level courses. Male instructors get better scores than females, and younger instructors are more popular than older ones. Certain other factors are also important determinants of evaluation scores. Our results suggest that an adjustment to the usual departmental rankings may be useful. Eastern Economic Journal (2009) 35, 37–51. doi:10.1057/palgrave.eej.9050042