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Int J Mol Sci. 2017 Jan 4;18(1). pii: E72. doi: 10.3390/ijms18010072.

d,l-Sulforaphane Induces ROS-Dependent Apoptosis in Human Gliomablastoma Cells by Inactivating STAT3 Signaling Pathway.

Miao Z1, Yu F2, Ren Y3, Yang J4.


d,l-Sulforaphane (SFN), a synthetic analogue of broccoli-derived isomer l-SFN, exerts cytotoxic effects on multiple tumor cell types through different mechanisms and is more potent than the l-isomer at inhibiting cancer growth. However, the means by which SFN impairs glioblastoma (GBM) cells remains poorly understood. In this study, we investigated the anti-cancer effect of SFN in GBM cells and determined the underlying molecular mechanisms. Cell viability assays, flow cytometry, immunofluorescence, and Western blot results revealed that SFN could induced apoptosis of GBM cells in a dose- and time-dependent manner, via up-regulation of caspase-3 and Bax, and down-regulation of Bcl-2. Mechanistically, SFN treatment led to increase the intracellular reactive oxygen species (ROS) level in GBM cells. Meanwhile, SFN also suppressed both constitutive and IL-6-induced phosphorylation of STAT3, and the activation of upstream JAK2 and Src tyrosine kinases, dose- and time-dependently. Moreover, blockage of ROS production by using the ROS inhibitor N-acetyl-l-cysteine totally reversed SFN-mediated down-regulation of JAK2/Src-STAT3 signaling activation and the subsequent effects on apoptosis by blocking the induction of apoptosis-related genes in GBM cells. Taken together, our data suggests that SFN induces apoptosis in GBM cells via ROS-dependent inactivation of STAT3 phosphorylation. These findings motivate further evaluation of SFN as a cancer chemopreventive agent in GBM treatment.

PMID: 28054986   PMCID: PMC5297707

Turk Neurosurg. 2017 Jan 19. doi: 10.5137/1019-5149.JTN.19111-16.1. [Epub ahead of print]

The Effect of Ascorbic Acid over the Etoposide- and Temozolomide-Mediated Cytotoxicity in Glioblastoma Cell Culture: A Molecular Study.

Göktürk D1, Kelebek HCeylan SYilmaz DM.


Glioblastoma (GBM) is one of the lethal central nervous system tumors. One of the widely used chemical agents for treatment of glioblastoma is temozolomide. It is an orally administered, DNA alkylating agent. DNA alkylation triggers the death of tumor cells. However, some tumor cells are able to repair this type of DNA damage, thus lower the therapeutic effect of temozolomide. Laboratory and clinical studies indicate that temozolomide\’s anticancer effects might be strengthened when combined with other chemotherapeutic agents, like etoposide, or antioxidant agents, like ascorbic acid. In this study we aimed to evaluate the cytotoxic and oxidative stress effects of ascorbic acid (1000 µM), temozolomide (100 µM) and etoposide (25 µM) agents alone, in dual and triple combinations in the glioblastoma U87 MG cell culture.


The cytotoxic and oxidative stress effects were investigated by the MTT and LC MS/MS analysis methods.


Cytotoxicity test results showed that etoposide, temozolomide, \”etoposide + ascorbic acid\”, \”temozolomide + ascorbic acid\”, \”temozolomide + etoposide\” and \”temozolomide + etoposide + ascorbic acid\” combinations have antiproliferative effects. The maximum antiproliferation response was observed in the \”temozolomide + etoposide + ascorbic acid\” added group. Similarly LC MS/MS analyses showed that minimum oxidative DNA damage was occured in the \”temozolomide + etoposide + ascorbic acid\” added group.


The results indicate that ascorbic acid decreases the cytotoxic and genotoxic effect of etoposide and etoposide-temozolomide combination, but it has no meaningful impact on the temozolomide\’s toxicity.

PMID: 28191621
Cancer Prevention
Oncotarget. 2017 Mar 28;8(13):20667-20678. doi: 10.18632/oncotarget.15400.

NADH autofluorescence, a new metabolic biomarker for cancer stem cells: Identification of Vitamin C and CAPE as natural products targeting “stemness”.


Here, we assembled a broad molecular “tool-kit” to interrogate the role of metabolic heterogeneity in the propagation of cancer stem-like cells (CSCs). First, we subjected MCF7 cells to “metabolic fractionation” by flow cytometry, using fluorescent mitochondrial probes to detect PCG1α activity, as well ROS and hydrogen-peroxide (H2O2) production; NADH levels were also monitored by auto-fluorescence. Then, the various cell populations were functionally assessed for “stem cell activity”, using the mammosphere assay (3D-spheroids). Our results indicate that a sub-population of MCF7 cells, with increased PGC1α activity, high mitochondrial ROS/H2O2 production and high NADH levels, all form mammospheres with a higher efficiency. Thus, it appears that mitochondrial oxidative stress and the anti-oxidant response both contribute to the promotion of mitochondrial biogenesis and oxidative metabolism in CSCs. Further validation was provided by using specific inhibitors to target metabolic processes (the NAD+ salvage pathway, glycolysis, mitochondrial protein synthesis and OXPHOS), significantly reducing CSC propagation. As a consequence, we have now identified a variety of clinically-approved drugs (stiripentol), natural products (caffeic acid phenyl ester (CAPE), ascorbic acid, silibinin) and experimental pharmaceuticals (actinonin, FK866, 2-DG), that can be used to effectively inhibit CSC activity. We discuss the use of CAPE (derived from honey-bee propolis) and Vitamin C, as potential natural therapeutic modalities. In this context, Vitamin C was ~10 times more potent than 2-DG for the targeting of CSCs. Similarly, stiripentol was between 50 to 100 times more potent than 2-DG.

KEYWORDS: NADH; cancer stem-like cells; metabolic cell fractionation; metabolic heterogeneity; mitochondria

PMID: 28223550  PMCID:PMC5400535

Pancreatic Cancer

Cancer Res. 2015 Aug 15;75(16):3314-26. doi: 10.1158/0008-5472.CAN-14-1707. Epub 2015 Jun 16.

Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer.

Du J1, Cieslak JA 3rd2, Welsh JL1, Sibenaller ZA2, Allen BG3, Wagner BA2, Kalen AL2, Doskey CM2, Strother RK2,Button AM4, Mott SL4, Smith B4, Tsai S5, Mezhir J3, Goswami PC6, Spitz DR6, Buettner GR6, Cullen JJ7.


The toxicity of pharmacologic ascorbate is mediated by the generation of H2O2 via the oxidation of ascorbate. Because pancreatic cancer cells are sensitive to H2O2 generated by ascorbate, they would also be expected to become sensitized to agents that increase oxidative damage such as ionizing radiation. The current study demonstrates that pharmacologic ascorbate enhances the cytotoxic effects of ionizing radiation as seen by decreased cell viability and clonogenic survival in all pancreatic cancer cell lines examined, but not in nontumorigenic pancreatic ductal epithelial cells. Ascorbate radiosensitization was associated with an increase in oxidative stress-induced DNA damage, which was reversed by catalase. In mice with established heterotopic and orthotopic pancreatic tumor xenografts, pharmacologic ascorbate combined with ionizing radiation decreased tumor growth and increased survival, without damaging the gastrointestinal tract or increasing systemic changes in parameters indicative of oxidative stress. Our results demonstrate the potential clinical utility of pharmacologic ascorbate as a radiosensitizer in the treatment of pancreatic cancer.

©2015 American Association for Cancer Research.

PMID: 26081808 PMCID: PMC4537815

Milk Thistle & Cancer

Milk thistle is a popular herb used most commonly for helping with liver diseases.  In a 2009 research study, an extract from Milk Thistle, called Silibinin, was found to have significant anti-tumor actions against many types of cancers, including of the skin, breast, lung, colon, bladder, prostate and kidney. 

Milk Thistle Extract & Prevention and Natural Treatment of Hepatocellular Carcinoma

A 2011 study to appear in the medical journal Current Pharmaceutical Biotechnology, noted how milk thistle extract can reduce the free radical damage and insulin resistance of liver cells in existing liver disease (eg: liver cirrhosis, non-alcoholic fatty liver, steatohepatitis).  Patients with these liver diseases have an increased risk of developing primary Hepatocellular Cancer (HCC).  Milk thistle extract has been shown to reduce tumor proliferation, angiogenesis (the development of blood vessels to cancer cells), and also reduce insulin resistance, in addition to known benefits of milk thistle (regenerating healthy liver cells, and reducing liver inflammation overall).  It also has anti-atherosclerotic benefits as well.  Milk thistle extract has shown to prevent the development of HCC in laboratory research.  The study concludes in saying that milk thistle extract can also be using alongside other cancer treatments (as an “adjuvant” cancer treatment) to improve the effectiveness of standard cancer treatments.


Silibinin – A Promising New Treatment for Cancer. 

Anticancer Agents Med Chem. 2009 Dec 16. Cheung CW, Gibbons N, Johnson DW, Nicol DL

Silymarin in the Prevention and Treatment of Liver Diseases and Primary Liver Cancer. Curr Pharm Biotechnol. 2011 April 5. [Epub ahead of print] Feher J, Lengyel G.