Inhibition of tumour metastasis by targeted delivery of antioxidant enzymes

Diagnostic significance and utility of circulating redox biomarkers in patients with gastric cancer - preliminary study

BACKGROUND

This study aimed to evaluate the redox status, antioxidant barrier, and oxidative damage to proteins, lipids, and DNA in patients with gastric cancer (GC). We are also the first to assess the diagnostic utility of redox parameters in patients with GC with respect to histopathological parameters.

METHODS

Fifty patients with gastric cancer and 50 healthy controls matched for sex and age were included in the study. The antioxidant barrier, redox status, and oxidative damage products were measured in serum/plasma samples using colorimetric or spectrophotometric methods.

RESULTS

The activity of superoxide dismutase - SOD (p < 0.05) was significantly higher, whereas the activities of catalase - CAT (p < 0.0001), glutathione peroxidase - GPx (p < 0.0001), glutathione reductase - GR (p < 0.0001), and reduced glutathione - GSH (p < 0.05) were considerably lower in GC patients than in the control group. The levels of total oxidant status - TOS (p < 0.0001), oxidative stress index - OSI (p < 0.0001), advanced oxidation protein products - AOPP (p < 0.0001), ischaemia modified albumin - IMA (p < 0.01), lipid hydroperoxides - LOOH (p < 0.0001), 8-IsoProstane - 8-Iso-P (p < 0.0001), and DNA/RNA (p < 0.0001) were significantly higher, and the levels of total antioxidant capacity - TAC (p < 0.0001) and total thiols (p < 0.0001) were considerably lower in patients compared to the healthy controls. Some redox parameters are characterized by high AUC values in patients with differentiated GC according to histopathological parameters.

CONCLUSIONS

Gastric cancer is strongly linked to a systemic redox imbalance and increased oxidative damage to proteins, lipids, and DNA. Redox biomarkers are potential diagnostic indicators of gastric cancer advancement.

Natural Products with Activity against Lung Cancer: A Review Focusing on the Tumor Microenvironment

Lung cancer is one of the most prevalent malignancies worldwide. Despite the undeniable progress in lung cancer research made over the past decade, it is still the leading cause of cancer-related deaths and continues to challenge scientists and researchers engaged in searching for therapeutics and drugs. The tumor microenvironment (TME) is recognized as one of the major hallmarks of epithelial cancers, including the majority of lung cancers, and is associated with tumorigenesis, progression, invasion, and metastasis. Targeting of the TME has received increasing attention in recent years. Natural products have historically made substantial contributions to pharmacotherapy, especially for cancer. In this review, we emphasize the role of the TME and summarize the experimental proof demonstrating the antitumor effects and underlying mechanisms of natural products that target the TME. We also review the effects of natural products used in combination with anticancer agents. Moreover, we highlight nanotechnology and other materials used to enhance the effects of natural products. Overall, our hope is that this review of these natural products will encourage more thoughts and ideas on therapeutic development to benefit lung cancer patients.

Copper-redox cycling by coumarin-di(2-picolyl)amine hybrid molecule leads to ROS-mediated DNA damage and apoptosis: A mechanism for cancer chemoprevention

Coumarin is an important bioactive pharmacophore. It is found in plants as a secondary metabolite and exhibits diverse pharmacological properties including anticancer effects against different malignancies. Therapeutic efficacy of coumarin derivatives depends on the pattern of substitution and conjugation with different moieties. Cancer cells contain elevated copper as compared to normal cells that plays a role in angiogenesis. Thus, targeting copper in malignant cells via copper chelators can serve as an attractive targeted anticancer strategy. Our previous efforts led to the synthesis of di(2-picolyl)amine-3(bromoacetyl)coumarin hybrid molecule (ligand-L) endowed with DNA/Cu(II) binding properties, and ROS generation ability in the presence of copper ions. In the present study, we aimed to validate copper-dependent cytotoxic action of ligand-L against malignant cells. For this, we used a cellular model system of copper (Cu) overloaded lymphocytes (CuOLs) to simulate malignancy-like condition. In CuOLs, lipid peroxidation/protein carbonylation, ROS generation, DNA fragmentation and apoptosis were investigated in the presence of ligand-L. Results showed that ligand-L-Cu(II) interaction leads to ROS generation, lipid peroxidation/protein carbonylation (oxidative stress parameters), DNA damage, up-regulation of p53 and mitochondrial-mediated apoptosis in treated lymphocytes. Further, pre-incubation with neocuproine (membrane permeable copper chelator) and ROS scavengers attenuated the DNA damage and apoptosis. These results suggest that cellular copper acts as molecular target for ligand-L to propagate redox cycling and generation of ROS via Fenton-like reaction leading to DNA damage and apoptosis. Further, we showed that ligand-L targets elevated copper in breast cancer MCF-7 and colon cancer HCT116 cells leading to a pro-oxidant inhibition of proliferation of cancer cells. In conclusion, we propose copper-dependent ROS-mediated mechanism for the cytotoxic action of ligand-L in malignant cells. Thus, targeting elevated copper represents an effective therapeutic strategy for selective cytotoxicity against malignant cells.

Juglanin inhibits lung cancer by regulation of apoptosis, ROS and autophagy induction

Juglanin (Jug) is obtained from the crude extract of Polygonum aviculare, exerting suppressive activity against cancer cell progression in vitro and in vivo. Juglanin administration causes apoptosis and reactive oxygen species (ROS) in different types of cells through regulating various signaling pathways. In our study, the effects of juglanin on non-small cell lung cancer were investigated. A significant role of juglanin in suppressing lung cancer growth was observed. Juglanin promoted apoptosis in lung cancer cells through increasing Caspase-3 and poly ADP-ribose polymerase (PARP) cleavage, which is regulated by TNF-related apoptosis-inducing ligand/Death receptors (TRAIL/DRs) relied on p53 activation. Anti-apoptotic members Bcl-2 and Bcl-xl were reduced, and pro-apoptotic members Bax and Bad were enhanced in cells and animals receiving juglanin. Additionally, nuclear factor-κB (NF-κB), phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) and mitogen-activated protein kinases (MAPKs) activation were inhibited by juglanin. Further, juglanin improved ROS and induced autophagy. ROS inhibitor N-acetyl-l-cysteine (NAC) reversed apoptosis induced by juglanin in cancer cells. The formation of autophagic vacoules and LC3/autophagy gene7 (ATG7)/Beclin1 (ATG6) over-expression were observed in juglanin-treated cells. Also, juglanin administration to mouse xenograft models inhibited lung cancer progression. Our study demonstrated that juglanin could be a promising candidate against human lung cancer progression.

Synthesis and mechanisms of action of novel harmine derivatives as potential antitumor agents

A series of novel harmine derivatives bearing a benzylindine substituent in position-1 of β-carboline ring were synthesized and evaluated as antitumor agents. The N2-benzylated β-carboline derivatives 3a–g represented the most interesting anticancer activities and compound 3c was found to be the most active agent to diverse cancer cell lines such as gastric carcinoma, melanoma and colorectal cancer. Notably, compound 3c showed low toxicity to normal cells. The treatment significantly induced cell apoptosis. Mechanistically, PI3K/AKT signaling pathway mediated compound 3c-induced apoptosis. Compound 3c inhibited phosphorylation of AKT and promoted the production of reactive oxygen species (ROS). The ROS scavenger, LNAC and GSH, could disturb the effect of compound 3c induced apoptosis and PI3K activity inhibitor LY294002 synergistically enhanced compound 3c efficacy. Moreover, the results from nude mice xenograft model showed that compound 3c treatment effectively inhibited tumor growth and decreased tumor weight. Collectively, our results demonstrated that compound 3c exerts apoptotic effect in cancer cells via suppression of phosphorylated AKT and evocation of ROS generation, which suggested that compound 3c might be served as a promising therapeutic agent for cancer treatment.

Hinokitiol Exerts Anticancer Activity through Downregulation of MMPs 9/2 and Enhancement of Catalase and SOD Enzymes: In Vivo Augmentation of Lung Histoarchitecture

Melanoma is extremely resistant to chemotherapy and the death rate is increasing hastily worldwide. Extracellular matrix promotes the migration and invasion of tumor cells through the production of matrix metalloproteinase (MMP)-2 and -9. Evidence has shown that natural dietary antioxidants are capable of inhibiting cancer cell growth. Our recent studies showed that hinokitiol, a natural bioactive compound, inhibited vascular smooth muscle cell proliferation and platelets aggregation. The present study is to investigate the anticancer efficacy of hinokitiol against B16-F10 melanoma cells via modulating tumor invasion factors MMPs, antioxidant enzymes in vitro. An in vivo mice model of histological investigation was performed to study the patterns of elastic and collagen fibers. Hinokitiol inhibited the expression and activity of MMPs-2 and -9 in B16-F10 melanoma cells, as measured by western blotting and gelatin zymography, respectively. An observed increase in protein expression of MMPs 2/9 in melanoma cells was significantly inhibited by hinokitiol. Notably, hinokitiol (1–5 μM) increased the activities of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) from the reduction in melanoma cells. Also, hinokitiol (2–10 µM) concentration dependently reduced in vitro Fenton reaction induced hydroxyl radical (OH·) formation. An in vivo study showed that hinokitiol treatment increased elastic fibers (EF), collagens dispersion, and improved alveolar alterations in the lungs of B16/F10 injected mice. Overall, our findings propose that hinokitiol may be a potent anticancer candidate through down regulation of MMPs 9/2, reduction of OH· production and enhancement of antioxidant enzymes SOD and CAT.

Molecular Design of Bisphosphonate-Modified Proteins for Efficient Bone Targeting In Vivo

To establish a rational molecular design for bisphosphonate (BP)-modified proteins for efficient bone targeting, a pharmacokinetic study was performed using a series of alendronate (ALN), a nitrogen-containing BP, modified proteins with various molecular weights and varying degrees of modification. Four proteins with different molecular weight—yeast glutathione reductase (GR; MW: 112,000 Da), bovine serum albumin (BSA; MW: 67,000 Da), recombinant human superoxide dismutase (SOD; MW: 32,000 Da), and chicken egg white lysozyme (LZM; MW: 14,000 Da)—were modified with ALN to obtain ALN-modified proteins. Pharmacokinetic analysis of the tissue distribution of the ALN-modified and unmodified proteins was performed after radiolabeling them with indium-111 (¹¹¹In) by using a bifunctional chelating agent. Calculation of tissue uptake clearances revealed that the bone uptake clearances of ¹¹¹In-ALN-modified proteins were proportional to the degree of ALN modification. ¹¹¹In-GR-ALN and BSA-ALN, the two high-molecular-weight proteins, efficiently accumulated in bones, regardless of the degree of ALN modification. Approximately 36 and 34% of the dose, respectively, was calculated to be delivered to the bones. In contrast, the maximum amounts taken up by bone were 18 and 13% of the dose for ¹¹¹In-SOD-ALN(32) and LZM-ALN(9), respectively, because of their high renal clearance. ¹¹¹In-SOD modified with both polyethylene glycol (PEG) and ALN (¹¹¹In-PEG-SOD-ALN) was efficiently delivered to the bone. Approximately 36% of the dose was estimated to be delivered to the bones. In an experimental bone metastasis mouse model, treatment with PEG-SOD-ALN significantly reduced the number of tumor cells in the bone of the mice. These results indicate that the combination of PEG and ALN modification is a promising approach for efficient bone targeting of proteins with a high total-body clearance.

The redox-active nanomaterial toolbox for cancer therapy

Advances in nanomaterials science contributed in recent years to develop new devices and systems in the micro and nanoscale for improving the diagnosis and treatment of cancer. Substantial evidences associate cancer cells and tumor microenvironment with reactive oxygen species (ROS), while conventional cancer treatments and particularly radiotherapy, are often mediated by ROS increase. However, the poor selectivity and the toxicity of these therapies encourage researchers to focus efforts in order to enhance delivery and to decrease side effects. Thus, the development of redox-active nanomaterials is an interesting approach to improve selectivity and outcome of cancer treatments. Herein, we describe an overview of recent advances in redox nanomaterials in the context of current and emerging strategies for cancer therapy based on ROS modulation.

Long term effect of curcumin in regulation of glycolytic pathway and angiogenesis via modulation of stress activated genes in prevention of cancer

Oxidative stress, an important factor in modulation of glycolytic pathway and induction of stress activated genes, is further augmented due to reduced antioxidant defense system, which promotes cancer progression via inducing angiogenesis. Curcumin, a naturally occurring chemopreventive phytochemical, is reported to inhibit carcinogenesis in various experimental animal models. However, the underlying mechanism involved in anticarcinogenic action of curcumin due to its long term effect is still to be reported because of its rapid metabolism, although metabolites are accumulated in tissues and remain for a longer time. Therefore, the long term effect of curcumin needs thorough investigation. The present study aimed to analyze the anticarcinogenic action of curcumin in liver, even after withdrawal of treatment in Dalton's lymphoma bearing mice. Oxidative stress observed during lymphoma progression reduced antioxidant enzyme activities, and induced angiogenesis as well as activation of early stress activated genes and glycolytic pathway. Curcumin treatment resulted in activation of antioxidant enzyme super oxide dismutase and down regulation of ROS level as well as activity of ROS producing enzyme NADPH:oxidase, expression of stress activated genes HIF-1α, cMyc and LDH activity towards normal level. Further, it lead to significant inhibition of angiogenesis, observed via MMPs activity, PKCα and VEGF level, as well as by matrigel plug assay. Thus findings of this study conclude that the long term effect of curcumin shows anticarcinogenic potential via induction of antioxidant defense system and inhibition of angiogenesis via down regulation of stress activated genes and glycolytic pathway in liver of lymphoma bearing mice.

Warburg meets autophagy: cancer-associated fibroblasts accelerate tumor growth and metastasis via oxidative stress, mitophagy, and aerobic glycolysis

SIGNIFICANCE

Here, we review certain recent advances in oxidative stress and tumor metabolism, which are related to understanding the contributions of the microenvironment in promoting tumor growth and metastasis. In the early 1920s, Otto Warburg, a Nobel Laureate, formulated a hypothesis to explain the "fundamental basis" of cancer, based on his observations that tumors displayed a metabolic shift toward glycolysis. In 1963, Christian de Duve, another Nobel Laureate, first coined the phrase auto-phagy, derived from the Greek words "auto" and "phagy," meaning "self" and "eating."

RECENT ADVANCES

Now, we see that these two ideas (autophagy and aerobic glycolysis) physically converge in the tumor stroma. First, cancer cells secrete hydrogen peroxide. Then, as a consequence, oxidative stress in cancer-associated fibroblasts drives autophagy, mitophagy, and aerobic glycolysis.

CRITICAL ISSUES

This "parasitic" metabolic coupling converts the stroma into a "factory" for the local production of recycled and high-energy nutrients (such as L-lactate)-to fuel oxidative mitochondrial metabolism in cancer cells. We believe that Warburg and de Duve would be pleased with this new two-compartment model for understanding tumor metabolism. It adds a novel stromal twist to two very well-established cancer paradigms: aerobic glycolysis and autophagy.

FUTURE DIRECTIONS

Undoubtedly, these new metabolic models will foster the development of novel biomarkers, and corresponding therapies, to achieve the goal of personalized cancer medicine. Given the central role that oxidative stress plays in this process, new powerful antioxidants should be developed in the fight against cancer.

Oxidative stress and antioxidant status in prostate cancer patients: relation to Gleason score, treatment and bone metastasis

Over the last decade, epidemiological, experimental and clinical studies have implicated oxidative stress in the development and progression of prostate cancer. In the present study, we evaluated the oxidative status and antioxidant defense in patients with prostate cancer (PCa) taking into consideration: treatment, Gleason score and bone metastasis. For this, we measured concentrations of plasmatic thiobarbituric acid reactive substances (TBARS), serum protein carbonylation, whole blood catalase (CAT) and superoxide dismutase (SOD) activities, as well as the plasma and erythrocyte thiol levels and serum vitamin C and E concentration. This study was performed on 55 patients with PCa and 55 healthy men. TBARS levels and serum protein carbonylation were higher in PCa patients than in controls and altered levels of antioxidants were found in these patients. CAT activity was decreased and SOD activity was higher in PCa patients when compared with controls. Non-protein thiol levels were increased, however, serum vitamin C and vitamin E content were reduced in PCa patients when compared with controls. In addition, different parameters analyzed in PCa patients based on metastasis, treatment and Gleason score showed changes in oxidative stress biomarkers and antioxidant defenses. These findings may indicate an imbalance in the oxidant/antioxidant status, supporting the idea that oxidative stress plays a role in PCa, moreover, the oxidative profile appear to be modified by bone metastasis, treatment and Gleason score.

Hydrogen peroxide fuels aging, inflammation, cancer metabolism and metastasis: the seed and soil also needs "fertilizer"

In 1889, Dr. Stephen Paget proposed the "seed and soil" hypothesis, which states that cancer cells (the seeds) need the proper microenvironment (the soil) for them to grow, spread and metastasize systemically. In this hypothesis, Dr. Paget rightfully recognized that the tumor microenvironment has an important role to play in cancer progression and metastasis. In this regard, a series of recent studies have elegantly shown that the production of hydrogen peroxide, by both cancer cells and cancer-associated fibroblasts, may provide the necessary "fertilizer," by driving accelerated aging, DNA damage, inflammation and cancer metabolism, in the tumor microenvironment. By secreting hydrogen peroxide, cancer cells and fibroblasts are mimicking the behavior of immune cells (macrophages/neutrophils), driving local and systemic inflammation, via the innate immune response (NFκB). Thus, we should consider using various therapeutic strategies (such as catalase and/or other anti-oxidants) to neutralize the production of cancer-associated hydrogen peroxide, thereby preventing tumor-stroma co-evolution and metastasis. The implications of these findings for overcoming chemo-resistance in cancer cells are also discussed in the context of hydrogen peroxide production and cancer metabolism.

Cancer cells metabolically "fertilize" the tumor microenvironment with hydrogen peroxide, driving the Warburg effect: implications for PET imaging of human tumors

Previously, we proposed that cancer cells behave as metabolic parasites, as they use targeted oxidative stress as a "weapon" to extract recycled nutrients from adjacent stromal cells. Oxidative stress in cancer-associated fibroblasts triggers autophagy and  mitophagy, resulting in compartmentalized cellular catabolism, loss of mitochondrial function, and the onset of aerobic glycolysis, in the tumor stroma. As such, cancer-associated fibroblasts produce high-energy nutrients (such as lactate and ketones) that fuel mitochondrial biogenesis, and oxidative metabolism in cancer cells. We have termed this new energy-transfer mechanism the "reverse Warburg effect." To further test the validity of this hypothesis, here we used an in vitro MCF7-fibroblast co-culture system, and quantitatively measured a variety of metabolic parameters by FACS analysis (analogous to laser-capture micro-dissection).  Mitochondrial activity, glucose uptake, and ROS production were measured with highly-sensitive fluorescent probes (MitoTracker, NBD-2-deoxy-glucose, and DCF-DA). Interestingly, using this approach, we directly show that cancer cells initially secrete hydrogen peroxide that then triggers oxidative stress in neighboring fibroblasts. Thus, oxidative stress is contagious (spreads like a virus) and is propagated laterally and vectorially from cancer cells to adjacent fibroblasts. Experimentally, we show that oxidative stress in cancer-associated fibroblasts quantitatively reduces mitochondrial activity, and increases glucose uptake, as the fibroblasts become more dependent on aerobic glycolysis.  Conversely, co-cultured cancer cells show significant increases in mitochondrial activity, and corresponding reductions in both glucose uptake and GLUT1 expression. Pre-treatment of co-cultures with extracellular catalase (an anti-oxidant enzyme that detoxifies hydrogen peroxide) blocks the onset of oxidative stress, and potently induces the death of cancer cells, likely via starvation.  Given that cancer-associated fibroblasts show the largest increases in glucose uptake, we suggest that PET imaging of human tumors, with Fluoro-2-deoxy-D-glucose (F-2-DG), may be specifically detecting the tumor stroma, rather than epithelial cancer cells.

Accelerated aging in the tumor microenvironment: connecting aging, inflammation and cancer metabolism with personalized medicine

Cancer is thought to be a disease associated with aging. Interestingly, normal aging is driven by the production of ROS and mitochondrial oxidative stress, resulting in the cumulative accumulation of DNA damage. Here, we discuss how ROS signaling, NFκB- and HIF1-activation in the tumor microenvironment induces a form of "accelerated aging," which leads to stromal inflammation and changes in cancer cell metabolism. Thus, we present a unified model where aging (ROS), inflammation (NFκB) and cancer metabolism (HIF1), act as co-conspirators to drive autophagy ("self-eating") in the tumor stroma. Then, autophagy in the tumor stroma provides high-energy "fuel" and the necessary chemical building blocks, for accelerated tumor growth and metastasis. Stromal ROS production acts as a "mutagenic motor" and allows cancer cells to buffer-at a distance-exactly how much of a mutagenic stimulus they receive, further driving tumor cell selection and evolution. Surviving cancer cells would be selected for the ability to induce ROS more effectively in stromal fibroblasts, so they could extract more nutrients from the stroma via autophagy. If lethal cancer is a disease of "accelerated host aging" in the tumor stroma, then cancer patients may benefit from therapy with powerful antioxidants. Antioxidant therapy should block the resulting DNA damage, and halt autophagy in the tumor stroma, effectively "cutting off the fuel supply" for cancer cells. These findings have important new implications for personalized cancer medicine, as they link aging, inflammation and cancer metabolism with novel strategies for more effective cancer diagnostics and therapeutics.

Mitochondrial targeted catalase suppresses invasive breast cancer in mice

BACKGROUND

Treatment of invasive breast cancer has an alarmingly high rate of failure because effective targets have not been identified. One potential target is mitochondrial generated reactive oxygen species (ROS) because ROS production has been associated with changes in substrate metabolism and lower concentration of anti-oxidant enzymes in tumor and stromal cells and increased metastatic potential.

METHODS

Transgenic mice expressing a human catalase gene (mCAT) were crossed with MMTV-PyMT transgenic mice that develop metastatic breast cancer. All mice (33 mCAT positive and 23 mCAT negative) were terminated at 110 days of age, when tumors were well advanced. Tumors were histologically assessed for invasiveness, proliferation and metastatic foci in the lungs. ROS levels and activation status of p38 MAPK were determined.

RESULTS

PyMT mice expressing mCAT had a 12.5 per cent incidence of high histological grade primary tumor invasiveness compared to a 62.5 per cent incidence in PyMT mice without mCAT. The histological grade correlated with incidence of metastasis with 56 per cent of PyMT mice positive for mCAT showing evidence of pulmonary metastasis compared to 85.4 per cent of PyMT mice negative for mCAT with pulmonary metastasis (p ≤ 0.05). PyMT tumor cells expressing mCAT had lower ROS levels and were more resistant to hydrogen peroxide-induced oxidative stress than wild type tumor cells, suggesting that mCAT has the potential of quenching intracellular ROS and subsequent invasive behavior. The metastatic tumor burden in PyMT mice expressing mCAT was 0.1 mm2/cm2 of lung tissue compared with 1.3 mm2/cm2 of lung tissue in PyMT mice expressing the wild type allele (p ≤ 0.01), indicating that mCAT could play a role in mitigating metastatic tumor progression at a distant organ site. Expression of mCAT in the lungs increased resistance to hydrogen peroxide-induced oxidative stress that was associated with decreased activation of p38MAPK suggesting ROS signaling is dependent on p38MAPK for at least some of its downstream effects.

CONCLUSION

Targeting catalase within mitochondria of tumor cells and tumor stromal cells suppresses ROS-driven tumor progression and metastasis. Therefore, increasing the antioxidant capacity of the mitochondrial compartment could be a rational therapeutic approach for invasive breast cancer.

Mitochondrial and plasma membrane lactate transporter and lactate dehydrogenase isoform expression in breast cancer cell lines

We hypothesized that dysregulation of lactate/pyruvate (monocarboxylate) transporters (MCT) and lactate dehydrogenase (LDH) isoforms contribute to the Warburg effect in cancer. Therefore, we assayed for the expression levels and the localizations of MCT (1, 2, and 4), and LDH (A and B) isoforms in breast cancer cell lines MCF-7 and MDA-MB-231 and compared results with those from a control, untransformed primary breast cell line, HMEC 184. Remarkably, MCT1 is not expressed in MDA-MB-231, but MCT1 is expressed in MCF-7 cells, where its abundance is less than in control HMEC 184 cells. When present in HMEC 184 and MCF-7 cells, MCT1 is localized to the plasma membrane. MCT2 and MCT4 were expressed in all the cell lines studied. MCT4 expression was higher in MDA-MB-231 compared with MCF-7 and HMEC 184 cells, whereas MCT2 abundance was higher in MCF-7 compared with MDA-MB-231 and HMEC 184 cells. Unlike MCT1, MCT2 and MCT4 were localized in mitochondria in addition to the plasma membrane. LDHA and LDHB were expressed in all the cell-lines, but abundances were higher in the two cancer cell lines than in the control cells. MCF-7 cells expressed mainly LDHB, while MDA-MB-231 and control cells expressed mainly LDHA. LDH isoforms were localized in mitochondria in addition to the cytosol. These localization patterns were the same in cancerous and control cell lines. In conclusion, MCT and LDH isoforms have distinct expression patterns in two breast cancer cell lines. These differences may contribute to divergent lactate dynamics and oxidative capacities in these cells, and offer possibilities for targeting cancer cells.

Ethanol extract of Ocimum sanctum exerts anti-metastatic activity through inactivation of matrix metalloproteinase-9 and enhancement of anti-oxidant enzymes

Ocimum sanctum has been known to possess various beneficial properties including anti-oxidative, anti-inflammatory and anti-cancer activities. In the present study, we investigated that ethanol extracts of O. sanctum (EEOS) had anti-metastatic activity through activation of anti-oxidative enzymes. EEOS exerted cytotoxicity against Lewis lung carcinoma (LLC) cells. Also, EEOS significantly inhibited cell adhesion and invasion as well as activities of matrix metalloproteinase-9 (MMP-9), but not MMP-2, indicating the important role of MMP-9 in anti-metastatic regulation of EEOS. In addition, EEOS significantly reduced the tumor nodule formation and lung weight in LLC-injected mice. Inhibitory effect of EEOS on metastasis was further confirmed by using hematoxylin and eosin (H&E) staining. Notably, we also found that EEOS enhanced activities of anti-oxidative enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) in a concentration-dependent manner. Taken together, our findings support that EEOS can be a potent anti-metastatic candidate through inactivation of MMP-9 and enhancement of anti-oxidant enzymes.

Reactive oxygen species and melanoma: an explanation for gender differences in survival?

Epidemiological research consistently shows a female advantage in melanoma survival. So far, no definite candidate for the explanation of this phenomenon has emerged. We propose that gender differences in oxidative stress caused by radical oxygen species (ROS) underlie these survival differences. It is known that males express lower amounts of anti-oxidant enzymes, resulting in more oxidative stress than females. The primary melanoma environment is characterized by high ROS levels, from exogenous sources as well as ROS production within melanoma cells themselves. ROS are known to be able to promote metastasis through a wide variety of mechanisms. We hypothesize that the higher levels of ROS in men enhance selection of ROS-resistance in melanoma cells. Subsequently, ROS can stimulate the metastatic potential of melanoma cells. In addition, due to the lower anti-oxidant defenses in men, ROS produced by melanoma cells cause more damage to healthy tissues surrounding the tumor, further stimulating metastasis. Therefore, ROS may explain the observed differences between males and females in melanoma survival.

MiRNA-29a regulates the expression of numerous proteins and reduces the invasiveness and proliferation of human carcinoma cell lines

In this study we have identified a functional role for miR-29a in cancer cell invasion and proliferation. MiRNA expression profiling of human NSCLC cell lines indicated that miR-29a levels were reduced in more invasive cell lines. Exogenous overexpression of miR-29a in both lung and pancreatic cancer cell lines resulted in a significant reduction in the invasion phenotype, as well as in proliferation. 2D DIGE proteomic profiling of cells transfected with pre-miR-29a or anti-miR-29a resulted in the identification of over 100 differentially regulated proteins. The fold change of protein expression was generally modest--in the range 1.2-1.7-fold. Only 14 were predicted computationally to have miR-29a seed sequences in their 3' UTR region. Subsequent studies using siRNA to knock down several candidate proteins from the 2D DIGE experiment identified RAN (a member of the RAS oncogene family) which significantly reduced the invasive capability of a model lung cancer cell line. We conclude that miR-29a has a significant anti-invasive and anti-proliferative effect on lung cancer cells in vitro and functions as an anti-oncomir. This function is likely mediated through the post-transcriptional fine tuning of the cellular levels of several proteins, both directly and indirectly, and in particular we provide some evidence that RAN represents one of these.

Prevention of pulmonary metastasis from subcutaneous tumors by binary system-based sustained delivery of catalase

Catalase delivery can be effective in inhibiting reactive oxygen species (ROS)-mediated acceleration of tumor metastasis. Our previous studies have demonstrated that increasing the plasma half-life of catalase by pegylation (PEG-catalase) significantly increases its potency of inhibiting experimental pulmonary metastasis in mice. In the present study, a biodegradable gelatin hydrogel formulation was used to further increase the circulation time of PEG-catalase. Implantation of (111)In-PEG-catalase/hydrogel into subcutaneous tissues maintained the radioactivity in plasma for more than 14 days. Then, the effect of the PEG-catalase/hydrogel on spontaneous pulmonary metastasis of tumor cells was evaluated in mice with subcutaneous tumor of B16-BL6/Luc cells, a murine melanoma cell line stably expressing luciferase. Measuring luciferase activity in the lung revealed that the PEG-catalase/hydrogel significantly (P<0.05) inhibited the pulmonary metastasis compared with PEG-catalase solution. These findings indicate that sustaining catalase activity in the blood circulation achieved by the use of pegylation and gelatin hydrogel can reduce the incidence of tumor cell metastasis.

Anticancer and carcinogenic properties of curcumin: considerations for its clinical development as a cancer chemopreventive and chemotherapeutic agent

A growing body of research suggests that curcumin, the major active constituent of the dietary spice turmeric, has potential for the prevention and therapy of cancer. Preclinical data have shown that curcumin can both inhibit the formation of tumors in animal models of carcinogenesis and act on a variety of molecular targets involved in cancer development. In vitro studies have demonstrated that curcumin is an efficient inducer of apoptosis and some degree of selectivity for cancer cells has been observed. Clinical trials have revealed that curcumin is well tolerated and may produce antitumor effects in people with precancerous lesions or who are at a high risk for developing cancer. This seems to indicate that curcumin is a pharmacologically safe agent that may be used in cancer chemoprevention and therapy. Both in vitro and in vivo studies have shown, however, that curcumin may produce toxic and carcinogenic effects under specific conditions. Curcumin may also alter the effectiveness of radiotherapy and chemotherapy. This review article analyzes the in vitro and in vivo cancer-related activities of curcumin and discusses that they are linked to its known antioxidant and pro-oxidant properties. Several considerations that may help develop curcumin as an anticancer agent are also discussed.

Experimental antioxidant therapy in ataxia telangiectasia

Ataxia telangiectasia (AT) is a rare genetic disorder characterized by immunodeficiency, early onset neurological degeneration, hypersensitivity to ionizing radiation and a high incidence of lymphoid cancers. The disease results from bi-allelic mutations in the AT mutated (ATM) gene involved in cell cycle checkpoint control and repair of DNA double-strand breaks. Evidence has been accumulating that oxidative stress is associated with AT and may be involved in the pathogenesis of the disease. This led to a hypothesis that antioxidant therapy may mitigate the symptoms of AT, especially neurological degeneration and tumorigenesis. Consequently, several studies examined the effect of antioxidants in Atm deficient mice used as an animal model of AT. N-acetyl-L-cysteine (NAC), EUK-189, tempol and 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO) have been tested for their chemopreventive properties and had some beneficial effects. In addition to antioxidants, cancer therapeutic agent dexamethasone was examined for cancer prevention in Atm deficient mice. Of the tested antioxidants, only NAC has wide clinical applications due to safety and efficacy and is available as an over-the-counter dietary supplement. In this article, we review chemoprevention studies in Atm deficient mice and, in more detail, our findings on the effect of NAC. The short-tem study showed that NAC suppressed genome rearrangements linked to cancer. The long-term study demonstrated that NAC reduced both the incidence and multiplicity of lymphoma.

Reactive oxygen species in tumor metastasis

Tumor metastasis is attributed not only to the abnormalities of cancer cells, but also to changes induced by the interaction of cancer cells and surrounding cells/tissues. The host immune response to cancer cells may contribute to an increased incidence of tumor metastasis. Surgical removal of tumor tissues can trigger tumor recurrence and metastatic tumor growth in distant organs. An important class of molecules involved in these events is the reactive oxygen species (ROS), which have been identified as involved in not only to tumor metastasis but also most disease processes. ROS will contribute to various aspects of malignant tumors, including carcinogenesis, aberrant growth, metastasis, and angiogenesis. High-level ROS, which can be reached by several anti-cancer treatments, suppresses tumor metastasis by destroying cancer cells because of the oxidative nature of the molecules. On the other hand, sublethal levels of ROS can induce additional changes in DNA of tumor cells to make those cells malignant, stimulate the proliferation of cancer cells, and activate the expression of various molecules, some of which assist cancer cells to form metastatic colonies. Thus, a precise understanding how ROS are generated and involved in tumor metastasis will help us to design better strategies to overcome such life-threatening events.

Oxystress inducing antitumor therapeutics via tumor-targeted delivery of PEG-conjugated D-amino acid oxidase

We had developed a H(2)O(2) generating enzyme, polyethylene glycol conjugated D-amino acid oxidase (PEG-DAO), which exhibited potent antitumor activity by generating toxic reactive oxygen species, namely oxidation therapy, subsequently showed remarkable antitumor effect on murine Sarcoma 180 solid tumor, by taking advantage of the enhanced permeability and retention effect. Along this line, we report here the preparation of PEG-DAO by use of recombinant DAO and its antitumor activity by using various tumor cell lines and tumor models. Recombinant DAO (rDAO) was obtained from E. coli BL21 (DE3) carrying the porcine DAO expression vector with high yield (20 mg/l) and high enzyme activity (5.3 U/mg). Pegylated rDAO (PEG-rDAO) showed high stability against sonication, repeated freezing/thawing, lyophilization and exhibited superior in vivo pharmacokinetics. PEG-rDAO had a molecular size of 65 kDa and existed as nanoparticles in aqueous solution with mean particle diameter of 119 nm. In vitro experiments showed strong cytotoxicity of PEG-rDAO against various tumor cells, whereas less cytotoxicity was found against various normal cells. In vivo antitumor treatment was carried out using 2 mice tumor models, namely colon 38 tumor and Meth A tumor model. PEG-rDAO was administered i.v. and after an adequate lag time, D-proline (the substrate of DAO) was injected i.p. to the tumor-bearing mice. Consequently, preferential generation of H(2)O(2) in the tumor was successfully achieved, which resulted in remarkable suppression of tumor growth without any visible side effects. These findings suggest a potential of PEG-rDAO as a novel anticancer strategy toward clinical development.

Combining cisplatin with cationized catalase decreases nephrotoxicity while improving antitumor activity

Cisplatin is frequently used to treat solid tumors; however, nephrotoxicity due to its reactive oxygen species-mediated effect limits its use. We tested the ability of cationized catalase, a catalase derivative, to inhibit nephrotoxicity in cisplatin-treated mice. Immunohistochemical analysis showed that the catalase derivative concentrated in the kidney more efficiently than native catalase. Repeated intravenous doses of cationized catalase significantly decreased cisplatin-induced changes in serum creatinine, blood urea nitrogen, nitrite/nitrate levels, lactic dehydrogenase activity, and renal total glutathione and malondialdehyde contents. In addition, cationized catalase effectively blunted cisplatin-induced proximal tubule necrosis but had no significant effect on the cisplatin-induced inhibition of subcutaneous tumor growth. Repeated doses of catalase, especially cationized catalase, significantly increased the survival of cisplatin-treated tumor-bearing mice preventing cisplatin-induced acute death. Our studies suggest that catalase and its derivatives inhibit cisplatin-induced nephrotoxicity, thus improving the efficiency of cisplatin to treat solid tumors.

Cationized catalase-loaded hydrogel for growth inhibition of peritoneally disseminated tumor cells

A previous study demonstrated that ethylenediamine-conjugated catalase (ED-catalase) inhibits peritoneal dissemination of tumor cells in mice. To increase its inhibitory effects by sustained release, a hydrogel formulation of ED-catalase was prepared using a biodegradable hydrogel consisting of an acidic gelatin with an isoelectric point of 5.0. Although intraperitoneally injected ED-catalase solution rapidly disappeared from the cavity, more than 10% of ED-catalase remained even at 14 days after implantation of ED-catalase/hydrogel into the cavity. Then, the effect of ED-catalase/hydrogel on peritoneal dissemination of tumor cells was evaluated by measuring the luciferase activity of abdominal organs after intraperitoneal inoculation of colon26/Luc, a colon adenocarcinoma stably expressing luciferase. ED-catalase/hydrogel showed a significantly (P<0.05) greater effect on inhibiting the growth of tumor cells than ED-catalase solution, demonstrating the importance of the retention of ED-catalase within the cavity as far as inhibition is concerned. Serial in vivo images of luciferase activity revealed that the ED-catalase/hydrogel significantly (P<0.05) retarded the growth rate of tumor cells. Survival of tumor-bearing mice supported the findings obtained with the luminescence-based analyses. These findings indicate that the sustained release of ED-catalase from hydrogels into the cavity is highly effective in inhibiting the growth of peritoneally disseminated tumor cells.

Effects of antioxidants on cancer prevention and neuromotor performance in Atm deficient mice

Ataxia telangiectasia (AT) is an autosomal recessive disorder characterized by immunodeficiency, neurodegeneration and cancer. The disease results from bi-allelic mutations in the AT mutated (ATM) gene involved in cell cycle checkpoint control and repair of DNA double-strand breaks. Evidence has been accumulating that oxidative stress is associated with AT and may be involved in the pathogenesis of the disease. This led to a hypothesis that antioxidants may alleviate the symptoms of AT. Consequently, several studies were conducted in Atm deficient mice to examine the role of antioxidants in cancer prevention and/or correction of neuromotor performance. N-acetyl-l-cysteine (NAC), EUK-189, tempol, and 5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl (CTMIO) have been tested in Atm deficient mice. In contrast to other antioxidants, NAC has been used in the clinical practice for many decades and is available as a dietary supplement. In this article, we review chemoprevention studies in Atm deficient mice and, in more detail, our findings on the effect of NAC. Our short-term study showed that NAC suppressed genome rearrangements linked to cancer. The long-term study demonstrated that NAC reduced the incidence and multiplicity of lymphoma and improved some aspects of motor performance.

Analysis of In Vivo Nuclear Factor-κB Activation during Liver Inflammation in Mice: Prevention by Catalase Delivery

Nuclear factor-kappaB (NF-kappaB) is a transcription factor that plays crucial roles in inflammation, immunity, cell proliferation, and apoptosis. Until now, there have been few studies of NF-kappaB activation in whole animals because of experimental difficulties. Here, we show that mice receiving a simple injection of plasmid vectors can be used to examine NF-kappaB activation in the liver. Two plasmid vectors, pNF-kappaB-Luc (firefly luciferase gene) and pRL-SV40 (Renilla reniformis luciferase gene), were injected into the tail vein of mice by the hydrodynamics-based procedure, an established method of gene transfer to mouse liver. Then, the ratio of the firefly and R. reniformis luciferase activities (F/R) was used as an indicator of the NF-kappaB activity in the liver. Injection of thioacetamide or lipopolysaccharide plus d-galactosamine increased the F/R ratio in the liver, and this was significantly (P<0.001) inhibited by an intravenous injection of catalase derivatives targeting liver nonparenchymal cells. Imaging the firefly luciferase expression in live mice clearly demonstrated that the catalase derivatives efficiently prevented the NF-kappaB-mediated expression of the firefly luciferase gene. Plasma transaminases and the survival rate of mice supported the findings obtained by the luminescence-based analyses. Thus, this method, which requires no genetic recombination techniques, is highly sensitive to the activation of NF-kappaB and allows us to continuously examine the activation in live animals. In conclusion, this novel, simple, and sensitive method can be used not only for analyzing the NF-kappaB activation in the organ under different inflammatory conditions but also for screening drug candidates for the prevention of liver inflammation.