Preoperative serum vascular endothelial growth factor levels: significance in ovarian cancer.

PURPOSE: To assess the clinical relevance of serum vascular endothelial growth factor (VEGF) levels in distinguishing patients with ovarian cancer from those with benign adnexal masses. Experimental Design: Preoperative serum VEGF levels were assessed in 101 women with invasive epithelial ovarian cancer, 16 with low malignant potential (LMP) ovarian tumors, and 34 women with benign ovarian tumors. VEGF levels were determined using an ELISA (R&D Systems, Minneapolis, MN). RESULTS: Ovarian cancer patients had a mean preoperative VEGF level of 549 pg/ml (median 379 pg/ml), which was significantly higher than those with benign adnexal masses (mean 228 pg/ml, median 155 pg/ml; P < 0.001) and LMP tumors (mean 200 pg/ml, median 129 pg/ml; P < 0.001). There were no significant differences in VEGF levels between individuals with benign masses and LMP tumors. The ability of VEGF to differentiate malignancy from benign masses at a cutoff VEGF level of 246 pg/ml gave a sensitivity of 74%, a specificity of 71%, a positive predictive value of 88%, and a negative predictive value of 48%. VEGF levels were also significantly higher in patients with stage I ovarian cancer compared with those with benign disease or LMP tumors. Among patients with ovarian cancer, there were no significant differences in VEGF levels based on age, stage, grade, or level of cytoreduction. The presence of ascites was associated with a significantly higher VEGF level (mean 667 pg/ml, median 445 pg/ml versus mean 317 pg/ml, median 293 pg/ml; P < 0.001). Various preoperative VEGF levels were assessed as a predictor of survival, and a VEGF level >380 pg/ml was associated with a hazard ratio of 2.13 (P = 0.009) by univariate analysis. In multivariate analysis of age, stage, cytoreduction, preoperative CA-125, grade, ascites, and VEGF levels above 380 pg/ml, only VEGF levels >380 pg/ml (hazard ratio 2.33; P = 0.02) and advanced stage (hazard ratio 9.03; P = 0.004) were significant. CONCLUSIONS: Preoperative VEGF levels may be useful in differentiating benign adnexal masses from malignancy. Preoperative VEGF levels >380 pg/ml are an independent risk factor for death because of disease.     

Use of E mu-PIM-1 transgenic mice short-term in vivo carcinogenicity testing: lymphoma induction by benzo[a]pyrene, but not by TPA

E mu-pim-1 transgenic mice are predisposed to develop lymphomas. Due to their low spontaneous tumour incidence and their increased sensitivity towards the lymphomagen ethylnitrosourea these mice may present an interesting model for short-term carcinogenicity testing. Here, we report on the further exploration of this transgenic mouse model with two additional carcinogens known to have, among others, the lymphohaematopoietic system as target, i.e. benzo[a]pyrene (B[a]P) and 12-O-tetradecanoylphorbol-13-acetate (TPA). B[a]P, given three times a week (by gavage) for 13 weeks at 4.3, 13 or 39 mg/kg body weight, resulted in a dose-related increase in lymphomas up to a 90% incidence in E(mu)-pim-1 mice during the observation period of 40 weeks. B[a]P also induced tumours of the forestomach within this observation period, though at a lower incidence and apparently equally effective in wildtype and transgenic mice. TPA, on the other hand, was unable to induce lymphomas (or tumours in any other organ) in either transgenic or wildtype animals within the observation period of 44 weeks, when applied dermally at the maximum tolerated dose of 3 microg/mouse, twice a week for 35 weeks. Molecular analysis showed that B[a]P-induced lymphomas in transgenic mice were of T-cell origin, 80% of which had elevated levels of c-myc expression. None of the lymphomas had increased N-myc expression and mutation analysis of the ras-gene family revealed a K-ras mutation in only one out of eight tumours investigated. Also, none of the lymphomas showed aberrant expression of p53 as determined by immunohistochemistry. It is concluded that the E mu-pim-1 mouse model will not be very suitable for short-term carcinogenicity testing in general: only genotoxic chemicals that have the lymphohaematopoietic system as target for carcinogenesis in wild- type mice, appear to be efficiently identified.      

Epigenetic silencing of maspin gene expression in human breast cancers

Maspin is a tumor suppressor whose expression is lost in many advanced breast cancers. Maspin has been shown to inhibit cell motility, invasion and metastasis; however, its precise role in normal mammary epithelium remains to be elucidated. Although expression of maspin mRNA is low or absent in most human breast cancer cells, the maspin gene is rarely re-arranged or deleted. We hypothesized that aberrant cytosine methylation and chromatin condensation of the maspin promoter participates in the silencing of maspin expression during neoplastic progression. To test this hypothesis, we compared cultured normal human mammary epithelial cells (HMECs) to 9 cultured human breast cancer cell lines. HMECs expressed maspin mRNA and displayed a completely non-methylated maspin gene promoter with an open chromatin structure. In contrast, 7 of 9 breast cancer cell lines had no detectable maspin expression and 6 of these 7 maspin-negative breast cancer cell lines also displayed an aberrant pattern of cytosine methylation of the maspin promoter. Interestingly, the maspin promoter was completely methylated in maspin-negative normal peripheral blood lymphocytes. This indicates that the maspin promoter is not a functional CpG island and that cytosine methylation of this region may contribute to normal tissue-restricted gene expression. Chromatin accessibility studies with MCF-7 cells, which lack maspin expression and have a methylated maspin promoter, showed a closed chromatin structure compared with HMECs. Moreover, maspin gene expression could be re-activated in MCF-7 cells by treatment with 5-aza-2;-deoxycytidine, a DNA demethylating agent. Thus, aberrant cytosine methylation and heterochromatinization of the maspin promoter may silence maspin gene expression, thereby contributing to the progression of human mammary cancer.     

Sterilization and its consequences

The purpose of this review is to analyze critically the two techniques of sterilization (bilateral tubal ligation [BTL] and vasectomy) so that a physician may provide informed consent about methods of sterilization. A MEDLINE search and extensive review of published literature dating back to 1966 was undertaken to compare preoperative counseling, operative procedures, postoperative complications, procedure-related costs, psychosocial consequences, and feasibility of reversal between BTL and a vasectomy. Compared with a vasectomy, BTL is 20 times more likely to have major complications, 10 to 37 times more likely to fail, and cost three times as much. Moreover, the procedure-related mortality, although rare, is 12 times higher with sterilization of the woman than of the man. Despite these advantages, 300,000 more BTLs were done in 1987 than vasectomies. In 1987, there were 976,000 sterilizations (65 percent BTLs and 35 percent vasectomies) with an overall cost of $1.8 billion. Over $260 million could have been saved if equal numbers of vasectomies and BTLs had been performed, or more than $800 million if 80 percent had been vasectomies, as was the case in 1971. The safest, most efficacious, and least expensive method of sterilization is vasectomy. For these reasons, physicians should recommend vasectomy when providing counseling on sterilization, despite the popularity of BTL. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians LEARNING OBJECTIVES: After completion of this article, the reader will be able to predict the failure rates and likelihood of successful reversal of tubal ligation and vasectomy; to recall the difference in cost between the two sterilization procedures, and to describe the short-term and long-term complications associated with each of the two methods of sterilization.     

In vitro rat myocyte cardiotoxicity model for antitumor antibiotics using adenosine triphosphate/protein ratios

Cumulative cardiotoxicity consistently limits the use of antitumor anthracyclines such as doxorubicin (DOX). Several in vivo and in vitro model systems have been developed for screening cardiotoxic agents. Problems with these models include excessive time and nonquantitative toxicity end points. We describe an in vitro system for culturing cardiac myocytes which overcomes these problems. Optimal myocyte cultures were obtained using serial 0.2% crude trypsin digestions of hearts from 1-2-day-old rats. Three-day-old myocyte cultures were treated with DOX for 6 h at concentrations of 0.1 to 10 micrograms/ml (0.18 to 18 microM). Electron microscopy performed on control and DOX-treated cultures showed characteristic histopathological signs of anthracycline damage. These changes included mitochondrial swelling, nuclear pleomorphism, chromatin clumping, and a diffuse loss of membrane integrity. Intracellular ATP, quantitated by the luciferase bioluminescence method, was shown to provide a simple and consistent quantitative biochemical marker of myocyte viability over the range of DOX concentrations used. The results showed both time- and dose-dependent decrements in ATP/protein ratios 72 h following exposure to DOX at concentrations greater than 0.1 microgram/ml. Leakage of lactate dehydrogenase activity, trypan blue uptake, and myocyte beating rates were variable and not as sensitive as ATP levels for evaluation of myocyte viability. Other cytotoxic agents which are not known to be cardiotoxic (dactinomycin, 1-beta-D-arabinofuranosylcytosine, fluorouracil, melphalan, and vincristine), required extremely high concentrations to produce myocyte damage in vitro. Tests with anthracycline analogues also demonstrated the ability of the assay to rank-order cardiotoxic agents on a weight basis: idarubicin greater than DOX greater than daunomycin greater than aclarubicin. When the in vitro drug concentrations required to lower ATP/protein ratios to 50% of controls were related to clinically achievable concentration x time products, DOX and daunomycin proved to be the most cardiotoxic in this series. These results suggest that comparative cardiotoxic screening studies may be performed in vitro using ATP levels in beating neonatal myocytes.