Program in Integrative Medicine, University of Kansas Medical Center, Kansas City, KS 66160, USA.

Two popular complementary, alternative, and integrative medicine therapies, high-dose intravenous ascorbic acid (AA) and intravenous glutathione (GSH), are often coadministered to cancer patients with unclear efficacy and drug-drug interaction. In this study we provide the first survey evidence for clinical use of iv GSH with iv AA. To address questions of efficacy and drug-drug interaction, we tested 10 cancer cell lines with AA, GSH, and their combination. The results showed that pharmacologic AA induced cytotoxicity in all tested cancer cells, with IC(50) less than 4 mM, a concentration easily achievable in humans. GSH reduced cytotoxicity by 10-95% by attenuating AA-induced H(2)O(2) production. Treatment in mouse pancreatic cancer xenografts showed that intraperitoneal AA at 4 g/kg daily reduced tumor volume by 42%. Addition of intraperitoneal GSH inhibited the AA-induced tumor volume reduction. Although all treatments (AA, GSH, and AA+GSH) improved survival rate, AA+GSH inhibited the cytotoxic effect of AA alone and failed to provide further survival benefit. These data confirm the pro-oxidative anti-cancermechanism of pharmacologic AA and suggest that AA and GSH administered together provide no additional benefit compared with AA alone. There is an antagonism between ascorbate and glutathione in treating cancer, and therefore iv AA and iv GSH should not be coadministered tocancer patients on the same day.

Copyright © 2011 Elsevier Inc. All rights reserved.

Free Radical and Radiation Biology Graduate Program, Department of Surgery, The University of Iowa College of Medicine, Iowa City, IA 52242, USA. joseph-cullen@uiowa.edu

Molecular and Clinical Nutrition Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.

Conventional treatment approaches have had little impact on the course of pancreatic cancer, which has the highest fatality rate among cancers. Gemcitabine, the primary therapeutic agent for pancreatic carcinoma, produces minimal survival benefit as a single agent. Therefore, numerous efforts have focused on gemcitabine combination treatments. Using a ratio design, this study established that combining pharmacologically achievable concentrations of ascorbate with gemcitabine resulted in a synergistic cytotoxic response in eight pancreatic tumor cell lines. Sensitization was evident regardless of inherent gemcitabine resistance and epithelial-mesenchymal phenotype. Our analysis suggested that the promiscuous oxidative actions of H(2)O(2) derived from pharmacologic ascorbate can culminate in synergism independent of the cancer cell’s underlying phenotype and resistance to gemcitabine monotherapy. Gemcitabine-ascorbate combinations administered to mice bearingpancreatic tumor xenografts consistently enhanced inhibition of growth compared to gemcitabine alone, produced 50% growth inhibition in a tumor type not responsive to gemcitabine, and demonstrated a gemcitabine dose-sparing effect. These data support the testing of pharmacologic ascorbate in adjunctive treatments for cancers prone to high failure rates with conventional therapeutic regimens, such as pancreatic cancer.

Department of Epidemiology, Mario Negri Institute for Pharmacological Research, Milan, Italy. francesca.bravi@marionegri.it

several studies have shown an inverse relation between vegetable and fruit intake and pancreatic cancer, but no specific beneficial component of such foods has been consistently identified. We considered the role of 15 selected vitamins and carotenoids and 6 minerals onpancreatic cancer risk in an Italian case-control study.

subjects were 326 patients with incident pancreatic cancer and 652 controls, admitted to the same hospitals as cases for acute conditions. Micronutrient computation was based on a validated and reproducible food-frequency questionnaire. We estimated the odds ratios (OR) and confidence intervals (CI) using conditional logistic regression models, adjusted for various confounding factors and for energy intake, according to the residual model.

comparing the highest to the lowest quintile of intake, the OR were 0.60 (95% CI 0.36-0.98) for vitamin E, 0.44 (95% CI 0.27-0.73) for vitamin C, 0.56 (95% CI 0.34-0.93) for folate, and 0.57 (95% CI 0.35-0.92) for potassium. No significant inverse associations were observed for α-carotene (OR = 0.69, 95% CI 0.43-1.12), β-carotene (OR = 0.64, 95% CI 0.39-1.06), and β-cryptoxanthin (OR = 0.66, 95% CI 0.39-1.09). No relation was found for other micronutrients considered.

our findings support a favorable role of vitamins E and C, selected carotenoids, and folate on pancreatic carcinogenesis.

Department of Surgery, University of Iowa College of Medicine, Iowa City, IA, USA. joseph-cullen@uiowa.edu

Ascorbate (ascorbic acid, vitamin C) is one of the early, unorthodox treatments for cancer. The evidence upon which people base the use of ascorbate in cancer treatment falls into two categories: clinical data on dose concentration relationships, and laboratory data describing potential cell toxicity with high concentrations of ascorbate in vitro. Clinical data show that when ascorbate is given orally, fasting plasma concentrations are tightly controlled by decreased absorption, increased urine excretion, and reduced ascorbate bioavailability. In contrast, when ascorbate is administered intravenously, concentrations in the millimolar level are achieved. Thus, it is clear that intravenous administration of ascorbate can yield very high plasma levels, while oral treatment does not.

Department of Gastrointestinal Medical Oncology, Unit 426, The University of Texas M. D. Anderson Cancer Center, 1550 Holcombe Boulevard, Houston, TX 77030-4009, USA.

To test the hypothesis that polymorphic variants of antioxidant genes modify the risk of pancreatic cancer, we examined seven single-nucleotide polymorphisms (SNPs) of genes coding for superoxide dismutase (SOD) 2, glutathione S-transferase alpha 4 (GSTA4), catalase and glutathione peroxidase in 575 patients with pancreatic adenocarcinoma and 648 healthy controls in a case-control study. Information on risk factors was collected by personal interview and dietary information was collected by a self-administered food frequency questionnaire. Genotypes were determined using the Taqman method. Adjusted odds ratio (AOR) and 95% confidence interval (CI) were estimated by unconditional logistic regression. No significant main effect of genotype was observed. A borderline significant interaction between diabetes and SOD2 Ex2+24T>C CT/TT genotype was observed (P(interaction) = 0.051); the AORs (95% CI) were 0.98 (0.73-1.32) for non-diabetics carrying the CT/TT genotype, 1.73 (0.94-3.18) for diabetics carrying the CC genotype and 3.49 (2.22-5.49) for diabetics carrying the CT/TT genotype compared with non-diabetics carrying the CC genotype. Moreover, the SOD2 -1221G>A AA genotype carriers had a significantly increased risk for pancreatic canceramong those with a low dietary vitamin E intake but decreased risk among those with a high vitamin E intake (P(interaction) = 0.002). There was a non-significant interaction between diabetes and GSTA4 Ex5-64G>A genotypes (P(interaction) = 0.078). No significant interaction between genotype with cigarette smoking or vitamin C intake was observed. These data suggest that genetic variations in antioxidant defenses modify the risk of pancreatic cancer in diabetics or individuals with a low dietary vitamin E intake.

Department of Surgery, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.

Pharmacologic concentrations of ascorbate may be effective in cancer therapeutics. We hypothesized that ascorbate concentrations achievable with i.v. dosing would be cytotoxic in pancreatic cancer for which the 5-year survival is <3%.

Pancreatic cancer cell lines were treated with ascorbate (0, 5, or 10 mmol/L) for 1 hour, then viability and clonogenic survival were determined. Pancreatic tumor cells were delivered s.c. into the flank region of nude mice and allowed to grow at which time they were randomized to receive either ascorbate (4 g/kg) or osmotically equivalent saline (1 mol/L) i.p. for 2 weeks.

There was a time- and dose-dependent increase in measured H(2)O(2) production with increased concentrations of ascorbate. Ascorbate decreased viability in all pancreatic cancer cell lines but had no effect on an immortalized pancreatic ductal epithelial cell line. Ascorbate decreased clonogenic survival of the pancreatic cancer cell lines, which was reversed by treatment of cells with scavengers of H(2)O(2). Treatment with ascorbate induced a caspase-independent cell death that was associated with autophagy. In vivo, treatment with ascorbate inhibited tumor growth and prolonged survival.

These results show that pharmacologic doses of ascorbate, easily achievable in humans, may have potential for therapy in pancreatic cancer.

Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, and Radiation Biology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.

Ascorbic acid is an essential nutrient commonly regarded as an antioxidant. In this study, we showed that ascorbate at pharmacologic concentrations was a prooxidant, generating hydrogen-peroxide-dependent cytotoxicity toward a variety of cancer cells in vitro without adversely affecting normal cells. To test this action in vivo, normal oral tight control was bypassed by parenteral ascorbate administration. Real-time microdialysis sampling in mice bearing glioblastoma xenografts showed that a single pharmacologic dose of ascorbate produced sustained ascorbate radical and hydrogen peroxide formation selectively within interstitial fluids of tumors but not in blood. Moreover, a regimen of daily pharmacologic ascorbate treatment significantly decreased growth rates of ovarian (P < 0.005), pancreatic (P < 0.05), and glioblastoma (P < 0.001) tumors established in mice. Similar pharmacologic concentrations were readily achieved in humans given ascorbate intravenously. These data suggest that ascorbate as a prodrug may have benefits in cancers with poor prognosis and limited therapeutic options.

Department of Surgery, The Second Hospital of TianJin Medical University, Tianjin, 300211, China.

To study the effect of recombinant adeno-associated virus (rAAV) vector bearing small inference RNA (siRNA) targeting hypoxia inducible factor 1alpha (HIF-1alpha) combined L: -ascorbate on pancreatic tumors in athymic mice primarily. A cassette encoding siRNA targeting HIF-1alpha mediated by rAAV was constructed, giving rAAV-siHIF. In vitro, rAAV-hrGFP, rAAV-siHIF and L: -ascorbate which were used alone or in combination were delivered to exponentially growing MiaPaCa2 cells. Then, we examined the expression of HIF-1alpha mRNA and protein, the secretion of VEGF in MiaPaCa2 cells under hypoxic condition with Real-time PCR, Western Blot, ELISA, respectively. In vivo, MiaPaCa2 cells were inoculated subcutaneously on the back of nude mice. Nude mice with xenograft tumor were randomly divided into equal groups and were injected with rAAV-hrGFP or rAAV-siHIF or were fed with L: -ascorbate. Then, we measured the size of tumor every 3 days and drew a tumor growth curve. After 30 days, all mice were sacrificed and the tumors were dissected. At last, we examined the expression of HIF-1alpha, VEGF and CD34 by immunohistochemistry and counted micro-vessel density (MVD). In vitro, we found that rAAV-siHIF could inhibit the expression of HIF-1alpha mRNA and protein in MiaPaCa2 human pancreatic cancer cells but L: -ascorbate could only restrain the expression of HIF-1alpha protein. Moreover, rAAV-siHIF and L: -ascorbate could all inhibit the secretion of vascular VEGF. In vivo, we found that rAAV-siHIF could inhibit the growth of nude mice xenograft tumor and the expression of HIF-1alpha and VEGF and MVD while L: -ascorbate can only inhibit the growth of xenograft tumor in the early and middle stage. These results suggest that rAAV-siHIF and L: -ascorbate can inhibit the growth of nude mice xenograft tumor and HIF-1alpha could be a target of pancreatic cancer genetic and pharmacological therapy.

Clinic of General, Visceral, Vascular and Thoracic Surgery, Charité Campus Mitte, Humboldt University of Berlin, Berlin, Germany.

Antioxidative vitamins are known to inhibit metastasis. Therefore we evaluated the impact of vitamins A (retinol), C (ascorbic acid) and E (alpha-tocopherol) on liver metastasis in a model of ductal pancreatic adenocarcinoma in hamster.

One hundred and twenty male Syrian hamsters were randomized into 8 groups (Gr.) (n = 15). Gr. 1-4 were given 0.5 ml normal saline subcutaneously (s.c.) weekly, whereas Gr. 5-8 received 10 mg N-nitrosobis(2-oxopropyl)amine (BOP)/kg body weight s.c. for 3 months for tumor induction. In the 13th week Gr. 2 and 6 were administered retinol, Gr. 3 and 7 received ascorbic acid and Gr. 4 and 8 were given alpha-tocopherol orally. No treatment was performed in Gr. 1 and 5. After 24 weeks animals were sacrificed, pancreas and liver were histologically determined. Activities of glutathione-peroxidase (GSH-Px), superoxide dismutase (SOD) and concentration of thiobarbituric-acid-reactive substances (TBARS) were analyzed in hepatic tissue.

Retinol and alpha-tocopherol decreased the incidence of liver metastases (44.4 vs. 86.7%, p < 0.05). The number and size of liver metastases were significantly reduced by retinol. Activities of GSH-Px and SOD were increased and concentration of TBARS was decreased in NML and LiMe by all vitamins.

Obviously, antioxidative vitamins prevent oxidative stress in hepatocytes. This may be one mechanism decreasing liver metastasis in pancreatic cancer in the present trial.

Copyright 2005 S. Karger AG, Basel and IAP.

MRI, Cancer Research Division, 1260 Memorex Drive, Santa Clara, CA 95050, USA.

Current treatment of pancreatic cancer is generally associated with poor prognosis, even if diagnosed early, owing to its aggressive rate of metastasis and non-responsiveness to chemotherapy and radiotherapy. Matrix metalloproteinases (MMPs) have received much attention in recent years for their role in various malignancies, and have been implicated in tumor invasion, metastasis, and angiogenesis.

Reported antitumor properties of ascorbic acid, lysine, proline, and green tea extract prompted us to investigate the effect of a combination of lysine, proline, arginine, ascorbic acid, and green tea extract on pancreatic cancer cell line MIA PaCa-2 for viability, MMP expression, invasion, and morphology.

Viability was evaluated based on cell proliferation by MTT assay and MMP expression in condition media by gelatinase zymography. Invasion through Matrigel was assayed and morphology was observed by hematoxylin and eosin (H+E)staining. Data was analyzed by independent sample “t” test.

The nutrient mixture (NM) did not inhibit cell proliferation at 10 microg/mL and exhibited a dose-dependent antiproliferative effect with maximum inhibition of 38% over the control at 1000 microg/mL. Zymography demonstrated production of only MMP-9, which showed a dose-dependent decreased expression that was abolished at 100 microg/mL of NM. Invasion through Matrigel was inhibited at 10, 50, 100, and 500 microg/mL by 66%, 66%, 87% and 100%, respectively. H&E staining did not indicate changes even at the highest concentration of NM.

Our results suggest that the formulation of green tea extract, lysine, proline, and ascorbic acid, tested as a promising adjunct to standard treatment of pancreatic cancer, by inhibiting MMP expression and invasion without toxic effects important parameters in cancermetastasis.

Center for the Improvement of Human Functioning, RENAC Project, Wichita, KS, USA.

A series of seven cases are presented in which intravenous vitamin C has been used as antineoplastic agent in the treatment of different types of cancers. The cancers cases reviewed are the following: Renal cell carcinoma (2), Colorectal cancer (1), Pancreatic cancer (1), Non-Hodgkin’s lymphoma (2) and breast cancer (1). Toxic reactions were not observed at these high doses of intravenous Vitamin C. All patients were prescreened for Glucose 6–phosphate dehydrogenase deficiency before administering intravenous Vitamin C in order to prevent hemolysis.

PMID:

 

15377059

 

[PubMed – indexed for MEDLINE]

Department of Biochemistry and Nutrition, Central Food Technological Research Institute, Mysore 570013, India.

Pancreatic cancer is an aggressive tumor with short median survival and high mortality rate. Alternative therapeutic modalities are currently being evaluated for pancreatic cancer. Here we studied the effects of ascorbyl stearate (Asc-S), a nontoxic, lipophilic derivative of ascorbic acid, onpancreatic cancer. Treatment of human pancreatic carcinoma cells with Asc-S (50-200 microM) resulted in a dose-dependent inhibition of their proliferation. Asc-S slowed down the cell cycle, accumulating, PANC-1 cells in late G2-M phase. Furthermore, Asc-S treatment (150 microM) markedly inhibited growth in soft agar and facilitated apoptosis of PANC-1 cells but not of Capan-2 cells. These effects were accompanied by a significant reduction in insulin-like growth factor 1 receptor (IGF1-R) expression, as compared to untreated controls. Interestingly, Capan-2 cells, the least responsive to Asc-S treatment, did not overexpress the IGF1-R. The results demonstrate the efficacy of Asc-S in inhibing growth ofpancreatic cancer cells and warrant additional studies to explore the potential utility of this compound as an alternative and/or adjuvant therapeutic modality for pancreatic cancer.