Immunohistochemical analysis of P-glycoprotein expression in diverse histological types of epithelial ovarian tumors.

P-glycoprotein is a transmembrane protein which acts as an energy-dependent drug efflux pump for a variety of anti-cancer drugs. The mdr-1 gene which encodes P-glycoprotein was successfully cloned in 1986. To investigate P-glycoprotein expression in diverse ovarian tumors, including benign, low malignant potential and malignant, immunohistochemical study was done using a monoclonal antibody (C 219). Overall, 8 out of the 59 epithelial ovarian tumors (13.6%) expressed P-glycoprotein. It was noted that 5 of the 12 mucinous tumors were found to express P-glycoprotein, while none of the 31 serous tumors were immunohistochemically positive. In 10 malignant ovarian tumors, P-glycoprotein immunostaining was examined both prior to and after chemotherapy. Nine of them did not express any P-glycoprotein before or after chemotherapy. However, one tumor expressed P-glycoprotein after six courses of multidrug resistance-related drug administration. These findings indicate that P-glycoprotein expression is not so common in ovarian tumors, regardless of their malignant potential. Nevertheless, the results suggest a strong association between P-glycoprotein expression and certain histological cell types in epithelial ovarian tumors. It is also possible that P-glycoprotein appears as a result of chemotherapy, but such a phenomenon can not occur unless chemotherapy is administered at high doses for a long period of time.</p

Effect of cisplatin on cell death and DNA crosslinking in rat mammary. Adenocarcinoma in vitro.

The pharmacodynamic effects of cisdiamminedichloroplatinum(II) (CDDP) in vitro have been reported, but the dosage and exposure time in vitro have not been based on clinical observations of the drug's actions in vivo. In this study, the authors attempted to evaluate the pharmacodynamic effects of CDDP in vitro in terms of cell survival and DNA crosslinking by simulating unbound CDDP administration at varying concentrations to a rat mammary adenocarcinoma line (known as line 66). CDDP exposure was conducted by both constant concentration procedures and a simulated in vivo procedure. Colony formation assay for the surviving fraction and alkaline elution assay for DNA crosslink measurement were performed in order to evaluate the pharmacodynamics of CDDP. Cell survival was a function of the area under the drug concentration time curve (AUC) of unbound CDDP (R2 = 0.77, P &#60; 0.002) for all drug exposure procedures as analyzed by the analysis of covariance test. There was a strong correlation between the surviving fraction and the crosslink index of the total amount of DNA crosslinks (R2 = 0.85, P &#60; 0.0005). Both the total amount of DNA-DNA crosslinks and the DNA-protein crosslinks, of which the latter were dominant, were affected not by the exposure procedures, but by the AUC value (P &#60; 0.002). The thresholds of cytocidal effect were 1.59 mg.h/l for the AUC and 0.008 for the crosslink index. The pharmacodynamic effects in vitro by simulated in vivo exposure were identical to those of constant.</p

Neoadjuvant treatment with docetaxel and the effects of irradiation for human ovarian adenocarcinoma and cervical squamous cell carcinoma in vitro.

The in vitro radiosensitizing effects of docetaxel have been reported, but the DNA damage caused by the irradiation after docetaxel exposure has not been investigated. In this study, the authors attempted to evaluate the radiosensitizing effects in terms of cell survival and DNA single-strand breaks in a human ovarian adenocarcinoma cell line (known as line BG-1) and a human cervical squamous cell carcinoma cell line (known as line SiHa). The cell lines were exposed to various concentrations of docetaxel (from 2.27 x 10(-3) to 2.27 microg/ml) to investigate the cytocidal effects by colony-formation assay. DNA single-strand breaks after exposure to 2.27 microg/ml of docetaxel for 30 min or 100 min were measured by the alkaline-elution assay. The remarkable cytotoxicity of docetaxel followed by irradiation was observed when concentrations were greater than 2.27 x 10(-2) microg/ml in both cell lines. The combination of docetaxel and irradiation appears to be supraadditive. The DNA single-strand breaks induced by the irradiation were enhanced in both cell lines (BG-1; P &#60; 0.01, SiHa; P &#60; 0.05). The synergistic cytocidal effect cannot be explained quantitatively only by the single-strand breaks. </p

Rapid and Sensitive Detection of Physical Status of Human Papillomavirus Type 16 DNA by Quantitative Real-Time PCR

A rapid quantitative real-time PCR method was employed to quantify the copy number of E2 and E6 genes for analysis of the physical status of human papillomavirus type 16 (HPV-16) DNA. Significant differences with respect to both copy numbers were found when more than 40% of HPV-16 DNA was integrated with disruption of the E2 gene in an experimental model. The physical status of HPV-16 DNA in 50 clinical samples was exclusively episomal in 21 cases (42%), concomitant in 14 cases (28%), and integrated in 15 cases (30%). The prevalence of integrated and/or concomitant forms of HPV-16 DNA increased with progression of cervical disease. Four of 11 cervical intraepithelial neoplasia involved integrated forms of HPV-16 DNA partially or exclusively. This rapid, sensitive technique is useful in the analysis of the physical status of HPV DNA