Search

We report the influence of fluence rate on the photobleaching and cell survival in Colo 26 multicell spheroids photosensitized by meta-tetra-(hydroxyphenyl)chlorin (mTHPC). Photosensitizer degradation and therapeutic efficacy increased dramatically and progressively when the fluence rate was reduced over the range from 90 to 5 mW cm−2. These experimental results were compared to a mathematical model of photobleaching based on self-sensitized singlet oxygen reactions with the photosensitizer ground state. This model incorporates photophysical parameters obtained from microelectrode measurements of oxygen depletion at the surface of mTHPC-sensitized spheroids and was refined by including the inhomogeneous distribution of mTHPC in spheroids and oxygen depletion in the bulk medium. Since the model is consistent with the experimental data we conclude that the fluence rate dependence of the cell survival and of mTHPC photobleaching is due to photochemical oxygen consumption and a predominantly singlet ...

We developed a model of orthotopic transplantation of bladder tumor cells in female Fischer rats using a new reproducible technique. After first performing the mechanical abrasion of a portion of the bladder urothelium with an Abrader© inserted transurethrally via a catheter, we administered a suspension of 5–40 × 106 viable AY-27 tumor cells in sterile phosphate-buffered saline to the bladder cavity. This rapidly led to a tumor growth incidence of approximately 100%. The induced bladder tumors grew expansively into the bladder cavity from the surface (mucosa) and gradually invaded the submucosa, muscles, serosa and surrounding tissue (high-stage invasive transitional cell carcinoma). Size and staging were related to the quantity of tumor cells instilled into the bladder cavity. This model matches the characteristics of human bladder tumor more closely than other bladder cancer models induced with tumor cells. Moreover, it presents many advantages: the method is reproducible, tumors grow rapidly, they are directly attached to the bladder surface and they are always located on the bladder wall, in line with the urethra. This proves especially helpful for evaluating chemotherapeutic agents by different means such as in vivo fluorescence spectroscopy, a noninvasive method used in photodynamic therapy, or other methods designed to detect and treat transitional cell carcinoma. © 2002 Wiley-Liss, Inc.

Coutier, S., Bezdetnaya, L., Foster, T. H., Parache, R-M. and Guillemin, F. Effect of Irradiation Fluence Rate on the Efficacy of Photodynamic Therapy and Tumor Oxygenation in Meta-Tetra (Hydroxyphenyl) Chlorin (mTHPC)-Sensitized HT29 Xenografts in Nude Mice. Radiat. Res. 158, 339–345 (2002). We present direct experimental evidence of the fluence-rate-dependent, radiation-induced variations in intratumor oxygen partial pressure (pO2) in HT29 human colon adenocarcinoma xenografts subjected to meta-tetra(hydroxyphenyl)chlorin (mTHPC)-based photodynamic therapy (PDT). The data establish a correlation between tumor oxygenation and treatment outcome. Tumor-bearing mice were injected with 0.3 mg/kg photosensitizer and subjected 72 h later to a 12 J/cm2 red light dose administered at fluence rates of 5, 30, 90 and 160 mW/cm2. A significant decrease in mean and median pO2 was registered at approximately half of the total radiation fluence was delivered in tumors treated at rates of 160 and 90 mW/cm2. Con...

International audience; Polyethylenimine (PEI) derivatives are potent polycationic nonviral vectors for gene transfer. The gene transfer efficiency of glucosylated and galactosylated PEI derivatives was optimized using green fluorescent protein gene as reporter gene in FaDu and PANC3 human carcinoma cell lines. Glucosylated or galactosylated PEI derivatives were found to be slightly less cytotoxic than unsubstituted PEI. Gene transfer efficiency was found to be related to DNA/cell number ratio and optimal gene transfer efficiency was achieved at 4 microg DNA/10(5) cells. PEI-DNA complexes were found to enter cells rapidly and were detected into cytoplasmic vesicles 2 hours post-transfection. Green fluorescent protein gene expression was detected 4-6 hours after transfection and reached maximal value 24 hours post-transfection. The results achieved demonstrated that glucosylated PEI yield higher and longer gene transfer efficiency than unsubstituted PEI. Using glucosylated PEI allowed to achieve significant gene transfer in more than 10% of the total cell population for more than 4 days. These data were then applied to p53 gene transfer in PANC3 cells bearing p53 gene deletion and consequently unable to initiate apoptosis. Using glucosylated PEI, p53 gene transfer was successfully achieved with subsequent recovery of p53 mRNA expression and transient P53 protein expression. P53 protein functionality was further demonstrated because transfected cells underwent apoptosis.

Since tamoxifen is widely used in breast cancer treatment and has been proposed for the prevention of breast cancer, its endometrial iatrogenic effects must be carefully examined. We have investigated the association between endometrial cancer and tamoxifen use or other treatments in women treated for breast cancer in a case-control study. Cases of endometrial cancer diagnosed after breast cancer (n = 135) and 467 controls matched for age, year of diagnosis of breast cancer and hospital and survival time with an intact uterus were included. Women who had received tamoxifen were significantly more likely to have endometrial cancer diagnosed than those who had not (crude relative risk = 4.9, p = 0.0001). Univariate and adjusted analyses showed that the risk increased with the length of treatment (p = 0.0001) or the cumulative dose of tamoxifen received (p = 0.0001), irrespective of the daily dose. Women who had undergone pelvic radiotherapy also had a higher risk (crude relative risk = 7.8, p = 0.0001). After adjusting for confounding factors, the risk was higher for tamoxifen users (p = 0.0012), treatment for more than 3 years (all p < 0.03) and pelvic radiotherapy (p = 0.012). Women who had endometrial cancer and had received tamoxifen had more advanced disease and poorer prognosis than those with endometrial cancer who had not received this treatment. Our results suggest a causal role of tamoxifen in endometrial cancer, particularly when used as currently proposed for breast cancer prevention. Pelvic radiotherapy may be an additional iatrogenic factor for women with breast cancer. Endometrial cancers diagnosed in women treated with tamoxifen have poorer prognosis. Women who receive tamoxifen for breast cancer should be offered gynaecological surveillance during and after treatment. A long-term evaluation of the risk-benefit ratio of tamoxifen as a preventive treatment for breast cancer is clearly warranted.

Thirty-eight previously untreated patients with a histologically proved diagnosis of nasopharyngeal carcinoma were evaluated for in vivo cell kinetics before treatment by conventional radiation therapy. Thirty-seven tumors were analyzed by flow cytometry. Values of median potential doubling time (Tpot), labelling index (LI), and duration of S phase (Ts) were, respectively, 10.9 days, 3.8%, and 10.8 hours. In 35 cases, the results obtained from two biopsies of the same tumor were compared. A good reproducibility was obtained for LI and Tpot (P < 0.01). Thirty-one tumors were analysed by immunohistochemistry and labelling index (HLI) was determined in 24 tumors with a percentage of labelled cells varying from 6.1% to 39.2% (median value = 18.5%). No correlation was found between LI and HLI, but when observations were focused on the restricted group of DNA aneuploid samples, mean values of LI and HLI were closer (respectively, 12.8 ± 4.5% and 18.3 ± 7.7%) and a good correlation was obtained (P = 0.01). Moreover, no difference in proliferation was found between diploid and aneuploid tumors. Considering these results, a combined Tpot was calculated that allowed classification of tumors as highly or slowly proliferative. Cytometry 29:165–172, 1997. © 1997 Wiley-Liss, Inc.

Global cerebral ischemia (four vessel model) was induced in renovascular hypertensive rats (two kidney, one clip model) chronically treated with intraperitoneal administration of angiotensin I converting enzyme inhibitors, either captopril (100 mg/kg per day) or Wy-44,655 (10 mg/kg per day). Mortality following cerebral ischemia was higher in renovascular hypertensive rats than in normotensive controls. Reduction of blood pressure with captopril or Wy-44,655, lowered mortality. In surviving renovascular hypertensive and normotensive rats cerebral ischemia induced hyperactivity and lesions of the CA1 area of the hippocampus. Prolonged treatment with captopril - but not with Wy-44,655 - reduced hyperactivity and the extent of the CA1 lesions. In conclusion, hypertension increases mortality following cerebral ischemia but does not affect the extent of brain injury in survivors. Prior treatment with converting enzyme inhibitors lowers mortality. Treatment with captopril attenuates brain injury in survivors.

Epidermoid carcinomas, clinically and histologically similar to human squamous cell carcinomas (SCC), were obtained in hairless Skh-1 mice. Tumor cells originated from chemically-induced skin cancers. We developed three models of orthotopic skin tumors: (1) intradermal injection of a tumor cell suspension, (2) superficial abrasion of the skin, cell grafting and application of a hydrocolloid dressing, (3) skin incision, seeding and application of a hydrocolloid dressing. Intradermal injection was 100% successful. Skin incision, displaying histological evidence of rapid invasive tumor growth, was 75% successful. Though skin tumor growth after abrasion was only 20% successful, the tumor histogenesis exactly imitated human SCC development. These carcinomas provide research models for further experiments such as photodynamic therapy or antiangiogenesis therapy.

We present direct experimental evidence of the fluence-rate-dependent, radiation-induced variations in intratumor oxygen partial pressure (pO(2)) in HT29 human colon adenocarcinoma xenografts subjected to meta-tetra(hydroxyphenyl)chlorin (mTHPC)-based photodynamic therapy (PDT). The data establish a correlation between tumor oxygenation and treatment outcome. Tumor-bearing mice were injected with 0.3 mg/kg photosensitizer and subjected 72 h later to a 12 J/cm(2) red light dose administered at fluence rates of 5, 30, 90 and 160 mW/cm(2). A significant decrease in mean and median pO(2) was registered at approximately half of the total radiation fluence was delivered in tumors treated at rates of 160 and 90 mW/cm(2). Conversely, with the two lower fluence rates, intratumor pO(2) was maintained at levels comparable to those measured before illumination. Tumor oxygenation values registered shortly after every treatment protocol were at least equal to baseline levels, thus excluding the possibility of significant acute vessel damage during illumination. The tumor regrowth profile correlated with the pO(2) values monitored during irradiation. Tumors treated with fluence rates of 5 and 30 mW/cm(2) exhibited significantly longer tumor quadrupling times than those treated at 160 and 90 mW/cm(2). Improved tumor destruction could be expected by reducing the rate and the extent of oxygen depletion during meta-tetra(hydroxyphenyl)chlorin photodynamic therapy using low fluence rates.

A tamoxifen resistant cell line (MCF7TAM) was established from tamoxifen sensitive MCF-7 human adenocarcinoma cells expressing estrogen receptors. The resistant cell line was found to express estrogen receptors to similar level as the parent cell line but the receptors were found to be altered, having lost their ability to bind estradiol or tamoxifen. The fluorescence of eosin-tamoxifen ionic association was used to investigate intracellular location of tamoxifen in both sensitive and resistant cell lines. Fluorescence emission spectra of eosin, tamoxifen and eosin-tamoxifen complex ((lambda) exc equals 480 nm) were analyzed and showed that maximal fluorescence intensity of the complex ((lambda) em equals 540 nm) was four times higher than that of eosin alone while tamoxifen alone did not emit any fluorescence in this spectral range. In MCF-7 cells, tamoxifen was found to be diffusively located in the cytoplasm and nuclear fluorescence intensity was significantly lower. No difference was observed in fluorescence intensity or location in tamoxifen resistant cells, although it has been previously correlated with clinical responsiveness. Improvement of this fluorescence microscopy methodology appears necessary to provide accurate results taking into account the complexity of tamoxifen resistance molecular pathways.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The presence of peroxisomes and their enzymatic content were investigated and compared in healthy and neoplastic human breast epithelial cells using cytochemical studies at the ultrastructural level as well as Western blot and biochemical analyses. Ultrastructural cytochemistry revealed the presence of these organelles in both normal and neoplastic breast tissues. Their mean diameter was 0.27 +/- 0.11 micron. No significant difference was noted between numbers of peroxisomes in normal and neoplastic breast epithelia. Catalase, D-amino acid oxidase, and urate oxidase were found to be expressed in mammary carcinoma and in surrounding non-malignant tissue when the postnuclear supernatant fractions prepared from homogenates were assessed by Western blot techniques. Their specific activities and that of fatty acyl CoA oxidase as determined spectrophotometrically were found to be diminished in the tumour when compared with the control tissue. On the other hand, no significant difference was found in the specific activity of the L-alpha-hydroxy acid oxidase of normal and neoplastic human breast tissues. Investigations of the relationship between peroxisomal enzymes and tumour grade revealed that catalase, urate oxidase, and fatty acyl CoA oxidase activities in breast neoplastic tissues belonging to grade III were significantly lower than in the adjacent normal tissues.

The presence of peroxisomes and their enzymic content were investigated and compared in healthy and neoplastic human colon epithelial cells using cytochemical studies at the ultrastructural level as well as biochemical analyses. Catalase-positive organelles were found to be more numerous in normal than in colonic neoplastic cells. Biochemical assays revealed that no D-aminoacid oxidase or L-alpha-hydroxyacid oxidase activity was detected in normal or tumor tissues. The specific activities of catalase, fatty-acyl CoA oxidase and enoyl-CoA hydratase/3 hydroxyacyl-CoA dehydrogenase (the so-called peroxisomal bifunctional enzyme of the beta-oxidation system) were found to be diminished in carcinoma cells compared with the control tissue. The fall in catalase activity correlated well with tumor stage according to Dukes, suggesting that this peroxisomal enzyme could be used as a potential prognostic marker.