Vitamins C and K3 Sensitize Human Urothelial Tumors to Gemcitabine

PURPOSE

We evaluated the antitumor effects of vitamins C and K3 for human urothelial carcinoma and the potential use of the combination of vitamins C plus K3 as a sensitizing agent for conventional chemotherapy for urothelial carcinoma.

MATERIALS AND METHODS

The antiproliferative and apoptotic effects of vitamin C alone, vitamin K3 alone, vitamins C plus K3, gemcitabine alone and gemcitabine plus vitamins C plus K3 were assessed in vitro by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, propidium iodide staining and flow cytometry. For in vivo studies we implanted UMUC-14 tumorigenic urothelial carcinoma cells into the subcutis of nude mice. One week later we treated 10 mice each with saline (control), vitamins C plus K3, gemcitabine or gemcitabine plus vitamins C plus K3. Treatment was continued for 4 weeks, followed by necropsy. Tumor volume was measured and tumor kinetics were established. Apoptosis and proliferation were evaluated in tumor sections using immunohistochemistry and TUNEL assay.

RESULTS

Vitamins C plus K3 induced cytostasis and caused apoptosis to a greater degree than either vitamin alone (p < 0.05). Vitamins C plus K3 also substantially augmented the effects of gemcitabine in vitro. There were 32.3% apoptosis with gemcitabine plus vitamins C plus K3, 5.3% with gemcitabine alone and 15.8% with vitamins C plus K3 alone (p < 0.05). In vivo tumor growth was substantially inhibited by gemcitabine plus vitamins C plus K3 compared with that in the control or for either agent alone. Mean tumor weight and growth rate in the gemcitabine plus vitamins C plus K3 group (237 mg and 11.3 mm3 daily) were decreased compared with those in the control (530 mg and 34.3 mm3 daily), and those for vitamins C plus K3 alone (490 mg and 25.2 mm3 daily) and gemcitabine alone (400 mg and 21.3 mm3 daily) (p < 0.05).

CONCLUSIONS

Vitamins C and K3 have significant antiproliferative and apoptotic effects when used in combination. This combination enhances the efficacy of gemcitabine against bladder cancer in vivo.

Atorvastatin: a potential chemopreventive agent in bladder cancer

OBJECTIVES

To evaluate a commonly used 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor-atorvastatin-for potential activity against human bladder cancer. Patients with bladder cancer often have concomitant hyperlipidemia and cardiac disease due to common risk factors such as smoking and advanced age. As such, they are often prescribed HMG-CoA reductase inhibitors (statins), which have been suggested to affect tumor growth patterns.

METHODS

Two human transitional cell carcinoma cell lines--RT4 and KU-7--were exposed to atorvastatin at concentrations from 0 (control) to 100 microM for 48 or 72 hours. The effects on cell proliferation, DNA synthesis, and apoptosis were respectively evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay and the thymidine incorporation assay and by quantifying DNA fragmentation by propidium iodide fluorescence and flow cytometry.

RESULTS

Atorvastatin inhibited cell proliferation and DNA synthesis in both bladder cancer cell lines. This led to significant cytotoxicity as demonstrated by DNA fragmentation and induction of apoptosis.

CONCLUSIONS

Atorvastatin exhibits significant antiproliferative and pro-apoptotic activity in human bladder cancer cells. This, coupled with its established clinical safety profile, provides a rationale for its use as a potential chemopreventive agent against bladder cancer.

Focal adhesion kinase silencing augments docetaxel-mediated apoptosis in ovarian cancer cells

OBJECTIVE

Docetaxel causes cell death through induction of apoptosis; however, cell death characteristics for docetaxel have not yet been fully elucidated. We examined the role of focal adhesion kinase (FAK) cleavage in docetaxel-mediated apoptosis.

METHODS

FAK degradation after treatment with docetaxel was determined in both taxane-sensitive (HeyA8 and SKOV3) and taxane-resistant (HeyA8-MDR and SKOV3-TR) ovarian cancer cell lines by Western blot analysis. Cell growth was determined with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. FAK-targeting small interfering RNA (siRNA) was used to decrease FAK expression. Apoptosis and caspase activity were determined using commercially available kits.

RESULTS

SKOV3 and HeyA8 cell lines were both sensitive to docetaxel (IC50 levels, 1-6.2 nmol/L), whereas the SKOV3-TR and HeyA8-MDR cells were resistant (IC50>or=250 nmol/L for both). Docetaxel induced high rates of apoptosis in SKOV3 and HeyA8 cells (84% and 66% apoptosis, respectively) but minimal apoptosis (5-8%) in SKOV3-TR and HeyA8-MDR cells. Similarly, FAK was cleaved in SKOV3 and HeyA8 cells in response to docetaxel treatment but unchanged in the resistant cells. Caspase-3 and caspase-8 activity also increased significantly in docetaxel-treated SKOV3 and HeyA8 cells but not in the taxane-resistant cells. DEVD-fmk (caspase-3 blocker) was able to block both FAK cleavage and apoptosis mediated by docetaxel in SKOV3 and HeyA8 cells. FAK siRNA transfection resulted in 70% to 90% decrease in FAK levels in all cell lines within 72 hours. FAK silencing augmented docetaxel-mediated growth inhibition (5- to 8-fold increase) and apoptosis in both of the taxane-sensitive and taxane-resistant cell lines.

CONCLUSIONS

Docetaxel induces FAK cleavage, mediated through activation of caspase-3, in taxane-sensitive ovarian cancer cells but not in taxane-resistant cells. The absence of FAK degradation may contribute to cell survival in taxane-resistant cells. FAK silencing promotes the in vitro efficacy of docetaxel in both taxane-sensitive and taxane-resistant cell lines and may serve as a novel therapeutic approach.