Thrombospondin-1 expression in epithelial ovarian carcinoma: association with p53 status, tumor angiogenesis, and survival in platinum-treated patients

OBJECTIVE

The regulation of the metastatic process in epithelial ovarian cancer has not been well defined. Similar to other tumor types, the angiogenic phenotype in ovarian cancer strongly influences clinical outcome, suggesting that the acquisition of a pro-angiogenic environment is essential to the process of ovarian cancer proliferation and metastasis. Thrombospondin-1 (TSP-1) is a potent peptide shown in other tumor systems to be associated with angiogenesis and possibly regulated by p53, a gene which is mutated in as high as 50% of advanced ovarian cancers. The purpose of this study was to investigate TSP-1 expression in invasive epithelial ovarian cancer and to examine the relationship between TSP-1 expression and the degree of angiogenesis. In addition, we examined whether TSP-1 expression was associated with overexpression of p53.

METHODS

Frozen sections obtained from 85 patients with invasive epithelial ovarian cancer were examined immunohistochemically for expression of TSP-1 and p53. The sections were examined microscopically by two investigators, who were blinded to the clinicopathologic variables. Outcome variables included the correlation among TSP-1, angiogenesis, and p53, as well as the association between TSP-1 expression and survival.

RESULTS

The majority (62%) of cases demonstrated high levels (3+) of TSP-1 expression; 7% demonstrated no TSP-1 expression. p53 was overexpressed in 55% of cases, and expression was inversely correlated with TSP-1 staining. Thirteen cancers had 0 or 1+ TSP-1 staining; 12 (92%) of these overexpressed the p53 protein. In contrast, only 49% of tumors with high expression of TSP-1 have overexpression of p53 (P = 0.02). TSP-1 was suggestive for improved survival in patients with advanced disease; high TSP-1 expression was associated with a median survival of 2.4 years compared to 1.5 years for patients with tumors having a lower degree of TSP-1 expression (P = 0.06).

CONCLUSION

These data suggest that TSP-1 may possess a tumor inhibitory function in patients with advanced epithelial ovarian carcinoma. The reduction of TSP-1 expression associated with overexpression of p53 may be coupled with the development of a pro-angiogenic environment and malignant phenotype.

Efficacy of anticholinergic and beta-adrenergic agonist treatment of maximal cholinergic bronchospasm in tracheally intubated rabbits

Cholinergically induced bronchoconstriction is thought to be a major cause of bronchospasm during anesthesia. We used tracheally intubated rabbits (4-mm endotracheal tube) stimulated with methacholine to assess the efficacy of beta-adrenergic agonist and anticholinergic treatment in reversing the increases in respiratory system resistance. Four groups were compared: (a) inhaled metaproterenol, 20 puffs via metered dose inhaler (0.65 mg/puff); (b) inhaled ipratropium bromide, 20 puffs from a metered dose inhaler (18 micrograms/puff); (c) 2 mg of intravenous atropine; and (d) no treatment after methacholine challenge as a control group. Methacholine increased respiratory system resistance from 0.041 +/- 0.001 (mean +/- SEM) to 0.098 +/- 0.006 cm H2O.mL-1.s-1 (P < 0.001). Whereas beta-adrenergic agonist treatment was ineffective in ameliorating bronchoconstriction, inhaled ipratropium bromide and atropine were highly effective, causing an 86%-88% reversal in the methacholine-induced increase in respiratory system resistance. Both these agents were also effective in improving dynamic compliance. We conclude that inhaled ipratropium bromide is effective in treating cholinergic bronchospasm even when administered via a small endotracheal tube and that the beta-adrenergic agonist metaproterenol is ineffective in rabbits in the face of maximal cholinergic stimulation.