Ascorbic Acid and a Cytostatic Inhibitor of Glycolysis Synergistically Induce Apoptosis in Non-Small Cell Lung Cancer Cells

Abstract

Ascorbic acid (AA) exhibits significant anticancer activity at pharmacologic doses achievable by parenteral administration that have minimal effects on normal cells. Thus, AA has potential uses as a chemotherapeutic agent alone or in combination with other therapeutics that specifically target cancer-cell metabolism. We compared the effects of AA and combinations of AA with the glycolysis inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3-PO) on the viability of three non-small cell lung cancer (NSCLC) cell lines to the effects on an immortalized lung epithelial cell line. AA concentrations of 0.5 to 5 mM caused a complete loss of viability in all NSCLC lines compared to a <10% loss of viability in the lung epithelial cell line. Combinations of AA and 3-PO synergistically enhanced cell death in all NSCLC cell lines at concentrations well below the IC50 concentrations for each compound alone. A synergistic interaction was not observed in combination treatments of lung epithelial cells and combination treatments that caused a complete loss of viability in NSCLC cells had modest effects on normal lung cell viability and reactive oxygen species (ROS) levels. Combination treatments induced dramatically higher ROS levels compared to treatment with AA and 3-PO alone in NSCLC cells and combination-induced cell death was inhibited by addition of catalase to the medium. Analyses of DNA fragmentation, poly (ADP-ribose) polymerase cleavage, annexin V-binding, and caspase activity demonstrated that AA-induced cell death is caused via the activation of apoptosis and that the combination treatments caused a synergistic induction of apoptosis. These results demonstrate the effectiveness of AA against NSCLC cells and that combinations of AA with 3-PO synergistically induce apoptosis via a ROS-dependent mechanism. These results support further evaluation of pharmacologic concentrations of AA as an adjuvant treatment for NSCLC and that combination of AA with glycolysis inhibitors may be a promising therapy for the treatment of NSCLC.

Effects of X-ray irradiation in combination with ascorbic acid on tumor control

“…Several studies have investigated apoptosis as part of tumor inhibition by AsA (21,22). The present study confirmed that apoptosis in the HT1080 cells was induced and G2/M cell cycle arrest was observed following treatment with >10 mM AsA (data not shown).…”

Vitamin B2 Sensitizes Cancer Cells to Vitamin-C-Induced Cell Death via Modulation of Akt and Bad Phosphorylation

“…The difference between two groups was assessed by the Student's t test using SPSS 18.0 for Microsoft Windows. 15,19,20 ) or the combination for the indicated time. Cell death was assessed using sub-G1 analysis.…”

Ascorbic Acid in Cancer: A Renewed Hope?

“…AA was also found to upregulate the expression of p53 to enhance cisplatin induced apoptosis in human colon cancer cells (HCT116) [12]. When AA is combined with a glycolysis inhibitor, 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen -1-one (3-PO), a synergistic induction of apoptosis via a ROSdependent pathway in non-small cell carcinoma cell lines (H1299, H661 and A549) was observed [13]. In addition, AA was shown to potentiate low dose methotrexate in inducing cancer cell death by caspase 3 and caspase 9 activation in hepatocellular carcinoma cells (Hep3B) [14].…”