Carrie Sun

Hydrogen peroxide mediates the cell growth and transformation caused by the mitogenic oxidase Nox1

Nox1, a homologue of gp91phox, the catalytic moiety of the superoxide (O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document})-generating NADPH oxidase of phagocytes, causes increased O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document} generation, increased mitotic rate, cell transformation, and tumorigenicity when expressed in NIH 3T3 fibroblasts. This study explores the role of reactive oxygen species (ROS) in regulating cell growth and transformation by Nox1. H2O2 concentration increased ≈10-fold in Nox1-expressing cells, compared with <2-fold increase in O\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \setlength{\oddsidemargin}{-69pt} \begin{document} \begin{equation*}{\mathrm{_{2}^{-}}}\end{equation*}\end{document}. When human catalase was expressed in Nox1-expressing cells, H2O2 concentration decreased, and the cells reverted to a normal appearance, the growth rate normalized, and cells no longer produced tumors in athymic mice. A large number of genes, including many related to cell cycle, growth, and cancer (but unrelated to oxidative stress), were expressed in Nox1-expressing cells, and more than 60% of these returned to normal levels on coexpression of catalase. Thus, H2O2 in low concentrations functions as an intracellular signal that triggers a genetic program related to cell growth.

An Inherited Heteroplasmic Mutation in Mitochondrial Gene COI in a Patient with Prostate Cancer Alters Reactive Oxygen, Reactive Nitrogen and Proliferation

Mitochondrial DNA (mtDNA) mutations have been found in many cancers but the physiological derangements caused by such mutations have remained elusive. Prostate cancer is associated with both inherited and somatic mutations in the cytochrome c oxidase (COI) gene. We present a prostate cancer patient-derived rare heteroplasmic mutation of this gene, part of mitochondrial respiratory complex IV. Functional studies indicate that this mutation leads to the simultaneous decrease in cytochrome oxidation, increase in reactive oxygen, and increased reactive nitrogen. These data suggest that mitochondrial DNA mutations resulting in increased reactive oxygen and reactive nitrogen generation may be involved in prostate cancer biology.

Cancer-Specific Loss of β-Defensin 1 in Renal and Prostatic Carcinomas

In a previous large-scale gene expression profiling study of renal epithelial neoplasms, human β-defensin-1 (DEFB1) was found to be significantly down-regulated in conventional clear cell (renal) carcinoma. We have now completed an expanded expression analysis of this gene. We performed immunohistochemical analysis for the DEFB1 protein in clinical specimens of both renal cell carcinoma and prostate cancer. In a subset of prostate cancers, we performed laser capture microdissection and RT-PCR to correlate mRNA levels with protein levels. Overall, 82% of prostate cancers exhibit either complete loss of protein expression or only minimal expression, whereas the adjacent benign epithelium retained expression in all cases. Similarly, 90% of renal cell carcinomas show cancer-specific loss of DEFB1 protein. In the prostate cancer subset analysis, mRNA levels correlate with protein levels. We have thus demonstrated the cancer-specific down-regulation of DEFB1 in a large sample of prostatic and renal carcinomas and validated one of the key findings of previous cancer gene profiling studies of prostatic and renal neoplasia.

Accumulation of mitochondrial DNA deletions in the malignant prostate of patients of different ages.

It has been shown that mitochondrial DNA (mtDNA) deletion mutations accumulate with age in many tissues of the body. However, to date no one has shown that these deletions occur in the malignant prostate. Therefore, we hypothesize that such deletions do occur in the prostate and increasingly so with advanced age. To test this hypothesis, DNA was isolated from 34 radical prostatectomy specimens, and the entire mitochondrial genome (16.5kb) was amplified using long range PCR (LXPCR). The LXPCR products were visualized by gel electrophoresis, and the presence of low molecular weight (<16kb) bands was considered evidence of large mtDNA deletions. In order to show that these lower molecular weight LXPCR bands were not simply PCR artifact, we also digested mtDNA from a subset of the same patients and did Southern analysis with a mtDNA probe. Southern blots confirmed the existence of large deletions in every sample tested. Furthermore, several of the specific deletions identified by LXPCR were also seen in the Southern blots. From the LXPCR data, we found that as the age of the specimen increased, so did the average number of low molecular weight bands (i.e. deletions). In particular, one prominent band was seen at 1.2kb and became more consistent with advanced age.

Mitochondrial DNA mutation stimulates prostate cancer growth in bone stromal environment

Mitochondrial DNA (mtDNA) mutations, inherited and somatically acquired, are common in clinical prostate cancer. We have developed model systems designed to study specific mtDNA mutations in controlled experiments. Because prostate cancer frequently metastasizes to bone we tested the hypothesis that mtDNA mutations enhance prostate cancer growth and survival in the bone microenvironment.

CAMPTOTHECIN ANALOGUES/CISPLASTIN: AN EFFECTIVE TREATMENT OF ADVANCED BLADDER CANCER IN A PRECLINICAL IN VIVO MODEL SYSTEM

OBJECTIVE To evaluate the impact of the camptothecin analogs on human TCC xenograft, both as monotherapy and in combination with cisplatin (CDDP). MATERIALS AND METHODS Human transitional cell carcinoma (TCC) xenograft tumor line (DU4184) tested by subrenal capsule assay in 112 nude mice(NM-SRCA). CDDP and the camptothecin analogs irinotecan (CPT-11) and 9-aminocamptothecin(9-AC) were evaluated. RESULTS Both of the camptothecin analogs showed significant short term tumor inhibition which translated into enhanced survival. Maximal tumor inhibition (>95%) was achieved when either of the camptothecin analogs was combined with CDDP with minimal host toxicity. This translated into 400% increase in median survival. While all controls were dead 39 days following tumor implantation, none of the combination treated animals had died. CONCLUSION The combination of CDDP with these camptothecin analogs is an effective therapy against this model of advanced TCC. These observations suggest potential clinical value.

Camptothecin analogues and vinblastine in the treatment of renal cell carcinoma: an in vivo study using a human orthotopic renal cancer xenograft ☆

To perform a series of in vivo cytotoxicity studies using a variety of doses of the comptothecin analogues 9-Aminocamptothecin (9-AC) and Irinotecan (CPT-11) with a human RCC xenograft tumor line (DU11983m). Using the subrenal capsule assay (80 nude mice) (NM-SRCA), 9-AC was evaluated at both low and high dosage levels (0.75 mg/kg and 1.25 mg/kg oral x10 doses over 12 days). Following an initial assessment of acute tumor inhibition, the study was extended to a survival assay with some cohorts receiving retreatment boluses on a once or twice weekly basis. CPT-11 was assessed at a dose of 100 mg/kg x3 over 9 days with weekly retreatment and two cohorts received 9-AC combined with Vinblastine (2.7 mg/kg) and Vinblastine alone, respectively. Tumor inhibition: tumor growth inhibition was significant (over 80%) with all cohorts receiving any camptothecin analogue and was virtually complete (>99% tumor inhibition) at the high dose 9-AC (1.25 mg/kg). Vinblastine alone achieved only moderate cytotoxic effect (46%) and induced the largest recorded cohort weight loss (toxicity). Survival analysis: the low and high dose 9-AC single agent cohorts were not significantly different; however, the CPT-11 cohort experienced maximal survival benefit. (P = 0.003) and the addition of Vinblastine did not enhance this survival advantage among the 9-AC cohorts. Control and single agent Vinblastine cohorts had the poorest survival with the treated group still surviving longer (P = 0.02). At 35 days after final assessment of acute tumor inhibition, all animals in both the control and Vinblastine alone cohorts were dead. None of the animals in any of the other cohorts (all of which had experienced a greater than 80% tumor inhibition) had died. No deaths occurred due to surgery or treatment toxicity and all deaths were deemed tumor related. CPT-11 and 9-AC produced a marked survival advantage in an orthotopic model of human advanced renal carcinoma and are identified as agents for further clinical assessment.

A mitochondrial DNA mutation influences the apoptotic effect of statins on prostate cancer.

Statins, 3‐hydroxy‐3 methylglutaryl coenzyme A (HMG‐CoA) reductase inhibitors, are currently the most widely used cholesterol‐lowering drugs. Previous epidemiological studies have suggested that there may be be an association between statin use and decreased risk of prostate cancer progression. Both inherited and somatic mutations of the mitochondrial genome are linked to prostate cancer. The purpose of this study was to determine if mitochondrial DNA (mtDNA) background and hence mitochondrial biochemistry can modulate the efficiency of statin as an anti‐prostate cancer agent.