Effect of hypoxia on the expression of phosphoglycerate kinase and antitumor activity of troxacitabine and gemcitabine in non-small cell lung carcinoma

Discovery, Synthesis, and Activity Evaluation of Novel Five-Membered Sulfur-Containing Heterocyclic Nucleosides as Potential Anticancer Agents In Vitro and In Vivo

A series of novel five-membered sulfur-containing heterocyclic nucleoside derivatives were designed, synthesized, and evaluated for their anticancer activities in vitro and in vivo. The structure-activity relationship studies revealed that some of them showed obvious antitumor activities in several cancer cell lines. Among them, compound 22o exhibited remarkable antiproliferative activity against HeLa cells and was more potent than cisplatin (IC50 = 2.80 vs 7.99 μM). Furthermore, mechanism studies indicated that 22o inhibited cell metastasis, induced cell apoptosis, decreased mitochondrial membrane potential, and activated autophagy through the PI3K-Akt-mTOR signaling pathway. Moreover, drug affinity responsive target stability and the cellular thermal shift assay revealed that 22o targeted RPS6 and inhibited its phosphorylation. Importantly, 22o inhibited the growth of the HeLa xenograft mouse model with a low systemic toxicity. These results indicated that 22o may serve as potent anticancer agents that merit further attention in future anticancer drug discovery.

Autonomous glucose metabolic reprogramming of tumour cells under hypoxia: opportunities for targeted therapy

Molecular oxygen (O₂) is a universal electron acceptor that is eventually synthesized into ATP in the mitochondrial respiratory chain of all metazoans. Therefore, hypoxia biology has become an organizational principle of cell evolution, metabolism and pathology. Hypoxia-inducible factor (HIF) mediates tumour cells to produce a series of glucose metabolism adaptations including the regulation of glucose catabolism, glycogen metabolism and the biological oxidation of glucose to hypoxia. Since HIF can regulate the energy metabolism of cancer cells and promote the survival of cancer cells, targeting HIF or HIF mediated metabolic enzymes may become one of the potential treatment methods for cancer. In this review, we summarize the established and recently discovered autonomous molecular mechanisms that can induce cell reprogramming of hypoxic glucose metabolism in tumors and explore opportunities for targeted therapy.

Computational modeling to determine key regulators of hypoxia effects on the lactate production in the glycolysis pathway

In solid tumors, hypoxia can trigger aberrant expression of transcription factors and genes, resulting in abnormal biological functions such as altered energetic pathways in cancer cells. Glucose metabolism is an important part of this phenomenon, which is associated with changes in the functional expression of transporters and enzymes involved in the glycolysis pathway. The latter phenomenon can finally lead to the lactate accumulation and pH dysregulation in the tumor microenvironment and subsequently further invasion and metastasis of cancer cells. Having capitalized on the computational modeling, in this study, for the first time, we aimed to investigate the effects of hypoxia-induced factor-1 (HIF-1) mediated hypoxia on the magnitude of functional expression of all the enzymes and transporters involved in the glycolysis process. The main objective was to establish a quantitative relationship between the hypoxia intensity and the intracellular lactate levels and determine the key regulators of the glycolysis pathway. This model clearly showed an increase in the lactate concentration during the oxygen depletion. The proposed model also predicted that the phosphofructokinase-1 and phosphoglucomutase enzymes might play the most important roles in the regulation of the lactate production.

Anticancer activity of complexes of the third row transition metals, rhenium, osmium, and iridium

A summary of recent developments on the anticancer activity of complexes of rhenium, osmium, and iridium is described.

Anticancer osmium complex inhibitors of the HIF-1α and p300 protein-protein interaction

The hypoxia inducible factor (HIF) pathway has been considered to be an attractive anti-cancer target. One strategy to inhibit HIF activity is through the disruption of the HIF-1α–p300 protein-protein interaction. We report herein the identification of an osmium(II) complex as the first metal-based inhibitor of the HIF-1α–p300 interaction. We evaluated the effect of complex 1 on HIF-1α signaling pathway in vitro and in cellulo by using the dual luciferase reporter assay, co-immunoprecipitation assay, and immunoblot assay. Complex 1 exhibited a dose-dependent inhibition of HRE-driven luciferase activity, with an IC₅₀ value of 1.22 μM. Complex 1 interfered with the HIF-1α–p300 interaction as revealed by a dose-dependent reduction of p300 co-precipitated with HIF-1α as the concentration of complex 1 was increased. Complex 1 repressed the phosphorylation of SRC, AKT and STAT3, and had no discernible effect on the activity of NF-κB. We anticipate that complex 1 could be utilized as a promising scaffold for the further development of more potent HIF-1α inhibitors for anti-cancer treatment.

Glucose metabolic phenotype of pancreatic cancer

AIM: To construct a global “metabolic phenotype” of pancreatic ductal adenocarcinoma (PDAC) reflecting tumour-related metabolic enzyme expression.

METHODS: A systematic review of the literature was performed using OvidSP and PubMed databases using keywords “pancreatic cancer” and individual glycolytic and mitochondrial oxidative phosphorylation (MOP) enzymes. Both human and animal studies investigating the oncological effect of enzyme expression changes and inhibitors in both an in vitro and in vivo setting were included in the review. Data reporting changes in enzyme expression and the effects on PDAC cells, such as survival and metastatic potential, were extracted to construct a metabolic phenotype.

RESULTS: Seven hundred and ten papers were initially retrieved, and were screened to meet the review inclusion criteria. 107 unique articles were identified as reporting data involving glycolytic enzymes, and 28 articles involving MOP enzymes in PDAC. Data extraction followed a pre-defined protocol. There is consistent over-expression of glycolytic enzymes and lactate dehydrogenase in keeping with the Warburg effect to facilitate rapid adenosine-triphosphate production from glycolysis. Certain isoforms of these enzymes were over-expressed specifically in PDAC. Altering expression levels of HK, PGI, FBA, enolase, PK-M2 and LDA-A with metabolic inhibitors have shown a favourable effect on PDAC, thus identifying these as potential therapeutic targets. However, the Warburg effect on MOP enzymes is less clear, with different expression levels at different points in the Krebs cycle resulting in a fundamental change of metabolite levels, suggesting that other essential anabolic pathways are being stimulated.

CONCLUSION: Further characterisation of the PDAC metabolic phenotype is necessary as currently there are few clinical studies and no successful clinical trials targeting metabolic enzymes.

Study of Malformin C, a Fungal Source Cyclic Pentapeptide, as an Anti-Cancer Drug

Malformin C, a fungal cyclic pentapeptide, has been claimed to have anti-cancer potential, but no in vivo study was available to substantiate this property. Therefore, we conducted in vitro and in vivo experiments to investigate its anti-cancer effects and toxicity. Our studies showed Malformin C inhibited Colon 38 and HCT 116 cell growth dose-dependently with an IC₅₀ of 0.27±0.07μM and 0.18±0.023μM respectively. This inhibition was explicated by Malformin C’s effect on G2/M arrest. Moreover, we observed up-regulated expression of phospho-histone H2A.X, p53, cleaved CASPASE 3 and LC3 after Malformin C treatment, while the apoptosis assay indicated an increased population of necrotic and late apoptotic cells. In vivo, the pathological study exhibited the acute toxicity of Malformin C at lethal dosage in BDF1 mice might be caused by an acute yet subtle inflammatory response, consistent with elevated IL-6 in the plasma cytokine assay. Further anti-tumor and toxicity experiments proved that 0.3mg/kg injected weekly was the best therapeutic dosage of Malformin C in Colon 38 xenografted BDF1 mice, whereas 0.1mg/kg every other day showed no effect with higher resistance, and 0.9mg/kg per week either led to fatal toxicity in seven-week old mice or displayed no advantage over 0.3mg/kg group in nine-week old mice. Overall, we conclude that Malformin C arrests Colon 38 cells in G2/M phase and induces multiple forms of cell death through necrosis, apoptosis and autophagy. Malformin C has potent cell growth inhibition activity, but the therapeutic index is too low to be an anti-cancer drug.

The radiosensitising effect of gemcitabine and its main metabolite dFdU under low oxygen conditions is in vitro not dependent on functional HIF-1 protein

Background

Regions within solid tumours often experience oxygen deprivation, which is associated with resistance to chemotherapy and irradiation. The aim of this study was to evaluate the radiosensitising effect of gemcitabine and its main metabolite dFdU under normoxia versus hypoxia and to determine whether hypoxia-inducible factor 1 (HIF-1) is involved in the radiosensitising mechanism.

Methods

Stable expression of dominant negative HIF-1α (dnHIF) in MDA-MB-231 breast cancer cells, that ablated endogenous HIF-1 transcriptional activity, was validated by western blot and functionality was assessed by HIF-1α activity assay. Cells were exposed to varying oxygen environments and treated with gemcitabine or dFdU for 24 h, followed by irradiation. Clonogenicity was then assessed. Using radiosensitising conditions, cells were collected for cell cycle analysis.

Results

HIF-1 activity was significantly inhibited in cells stably expressing dnHIF. A clear radiosensitising effect under normoxia and hypoxia was observed for both gemcitabine and dFdU. No significant difference in radiobiological parameters between HIF-1 proficient and HIF-1 deficient MDA-MB-231 cells was demonstrated.

Conclusions

For the first time, radiosensitisation by dFdU, the main metabolite of gemcitabine, was demonstrated under low oxygen conditions. No major role for functional HIF-1 protein in radiosensitisation by gemcitabine or dFdU could be shown.

Phosphoglycerate kinase 1 promotes radioresistance in U251 human glioma cells

Phosphoglycerate kinase 1 (PGK1) has been found to be increased in radioresistant astrocytomas. The present study was designed to investigate the potential role of PGK1 in the radioresistance in U251 human cells. Quantitative PCR and western blot analysis were performed to evaluate PGK1 expression for mRNA levels and protein levels, respectively. The short hairpin RNA (shRNA)-PGK1 and the high expression plasmids were transfected to radioresistant U251 cells (RR-U251 cells) or normal U251 cells using lipofectamine™ 2000. The cell viability was determined by MTT assay. The wound-healing assay (WHA) was used to evaluate cell migration ability. Cell invasion abilities were examined using a Transwell culture chamber system. Our results showed that the expression of PGK1 was significantly increased in RR-U251 cells compared to normal U251 cells. Following irradiation, the cell viability as well as the migration and invasion ability were significantly higher in RR-U251 cells compared with normal U251 cells. Downregulating PGK1 using shRNA induced a significantly downregulated cell viability and decreased migration and invasion ability, and overexpression of PGK1 contributed to upregulated cell viability and increased migration and invasion ability, both in RR-U251 cells and normal U251 cells. These findings suggest that PGK1 could promote radioresistance in U251 human cells.

Synergistic interaction of novel lactate dehydrogenase inhibitors with gemcitabine against pancreatic cancer cells in hypoxia

Background:

Hypoxia is a driving force in pancreatic-ductal-adenocarcinoma (PDAC) growth, metastasis and chemoresistance. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis, ensuring supply of energy and anabolites in hypoxic-environments. Therefore, we investigated the molecular mechanisms underlying the pharmacological interaction of novel LDH-A inhibitors in combination with gemcitabine in PDAC cells.

Methods:

Lactate dehydrogenase A levels were studied by quantitative RT–PCR, western blot, immunofluorescence and activity assays in 14 PDAC cells, including primary-cell-cultures and spheroids, in normoxic and hypoxic conditions. Cell proliferation, migration and key determinants of drug activity were evaluated by sulforhodamine-B-assay, wound-healing assay, PCR and LC-MS/MS.

Results:

Lactate dehydrogenase A was significantly increased under hypoxic conditions (1% O₂), where the novel LDH-A inhibitors proved to be particularly effective (e.g., with IC₅₀ values of 0.9 vs 16.3 μM for NHI-1 in LPC006 in hypoxia vs normoxia, respectively). These compounds induced apoptosis, affected invasiveness and spheroid-growth, reducing expression of metalloproteinases and cancer-stem-like-cells markers (CD133+). Their synergistic interaction with gemcitabine, with combination index values <0.4 in hypoxia, might also be attributed to modulation of gemcitabine metabolism, overcoming the reduced synthesis of phosphorylated metabolites.

Conclusion:

Lactate dehydrogenase A is a viable target in PDAC, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours.

Modulators of HIF1α and NFkB in Cancer Treatment: Is it a Rational Approach for Controlling Malignant Progression?

HIF1α and NFkB are two transcription factors very frequently activated in tumors and involved in tumor growth, progression, and resistance to chemotherapy. In fact, HIF1α and NFkB together regulate transcription of over a thousand genes that, in turn, control vital cellular processes such as adaptation to the hypoxia, metabolic reprograming, inflammatory reparative response, extracellular matrix digestion, migration and invasion, adhesion, etc. Because of this wide involvement they could control in an integrated manner the origin of the malignant phenotype. Interestingly, hypoxia and inflammation have been sequentially bridged in tumors by the discovery that alarmin receptors genes such as RAGE, P2X7, and some TLRs, are activated by HIF1α; and that, in turn, alarmin receptors strongly activate NFkB and proinflammatory gene expression, evidencing all the hallmarks of the malignant phenotype. Recently, a large number of drugs have been identified that inhibit one or both transcription factors with promising results in terms of controlling tumor progression. In addition, many of these molecules are natural compounds or off-label drugs already used to cure other pathologies. Some of them are undergoing clinical trials and soon they will be used alone or in combination with standard anti-tumoral agents to achieve a better treatment of tumors with reduction of metastasis formation and, more importantly, with a net increase in survival. This review highlights the central role of HIF1α activated in hypoxic regions of the tumor, of NFkB activation and proinflammatory gene expression in transformed cells to understand their progression toward malignancy. Different molecules and strategies to inhibit these transcription factors will be reviewed. Finally, the central role of a new class of deacetylases called Sirtuins in regulating HIF1α and NFkB activity will be outlined.

Impact of tumor blood flow modulation on tumor sensitivity to the bioreductive drug banoxantrone

We investigated the hypoxia-dependent cytotoxicity of AQ4N (banoxantrone) using a panel of 13 cancer cell lines and studied its relationship to the expression of the quinone reductase DT-diaphorase (NQO1), which is widely found in cancer cells. We also investigated pharmacologic treatments that increase tumor hypoxia in vivo and their impact on AQ4N chemosensitivity in a solid tumor xenograft model. AQ4N showed ≥ 8-fold higher cytotoxicity under hypoxia than normoxia in cultures of 9L rat gliosarcoma and H460 human non-small-cell lung carcinoma cells but not for 11 other human cancer cell lines. DT-diaphorase protein levels and AQ4N chemosensitivity were poorly correlated across the cancer cell line panel, and AQ4N chemosensitivity was not affected by DT-diaphorase inhibitors. The vasodilator hydralazine decreased tumor perfusion and increased tumor hypoxia in 9L tumor xenografts, and to a lesser extent in H460 tumor xenografts. However, hydralazine did not increase AQ4N-dependent antitumor activity. Combination of AQ4N with the angiogenesis inhibitor axitinib, which increases 9L tumor hypoxia, transiently increased antitumor activity but with an increase in host toxicity. These findings indicate that the capacity to bioactivate AQ4N is not dependent on DT-diaphorase and is not widespread in cultured cancer cell lines. Moreover, the activation of AQ4N cytotoxicity in vivo requires tumor hypoxia that is more extensive or prolonged than can readily be achieved by vasodilation or by antiangiogenic drug treatment.

Hypoxia inducible factor-1alpha gene polymorphism G1790A and its interaction with tobacco and alcohol consumptions increase susceptibility to hepatocellular carcinoma

BACKGROUND AND OBJECTIVES

The aim of this study was to examine the potential associations of two hypoxia inducible factor-1alpha (HIF-1alpha) gene polymorphisms, C1772T and G1790A, with the susceptibility and clinicopathological status of hepatocellular carcinoma.

METHODS

A total of 449 subjects, including 347 healthy controls and 102 patients with hepatocellular carcinoma, were recruited in this study and subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analyses to estimate the impact of these two polymorphic variants on hepatocellular carcinoma.

RESULTS

G1790A heterozygotes showed a higher risk for hepatocellular carcinoma, compared with GG genotypes after adjusting for other confounders (AOR = 3.97; 95%CI = 1.70-9.22), indicating a significant association between hepatocellular carcinoma susceptibility and G1790A polymorphism. Moreover, results also revealed the presence of synergistic effect between gene polymorphism of HIF-1alpha G1790A and environmental risk factors, such as tobacco and alcohol consumptions while there was no significant association between HIF-1alpha gene polymorphism and clinicopathological parameters of hepatocellular carcinoma.

CONCLUSIONS

Genetic polymorphism at G1790A of HIF-1alpha is an important factor for determining the susceptibility to hepatocellular carcinoma. The interaction effects of G1790A heterozygotes to tobacco and to alcohol consumption significantly increase the risk to develop hepatocellular carcinoma.

Protein expression changes in human monocytic THP-1 cells treated with lipoteichoic acid from Lactobacillus plantarum and Staphylococcus aureus

Lipoteichoic acid (LTA) from Staphylococcus aureus (aLTA) and from Lactobacillus plantarum LTA (pLTA) are both recognized by Toll-like receptor 2 (TLR2), but cause different stimulatory effects on the innate immune and inflammatory responses, and their underlying cellular mechanisms are unknown. In this study, comparative proteome analysis was performed using two-dimensional gel electrophoresis and mass spectrometry on protein extracts from human monocyte THP-1 cells stimulated with either aLTA or pLTA. Differentially expressed proteins might be involved in innate immunity and inflammation. Cells treated with aLTA and with pLTA showed different protein expression profiles. Of 60 identified proteins, 10 were present only in treated cells (8 in aLTA-treated only, and 2 in pLTA-treated only), 1 protein (IMPDH2) was suppressed by pLTA, and 49 were up- or down-regulated more than three-fold by aLTA- or pLTA- stimulation. Several proteins involved in immunity or inflammation, antioxidation, or RNA processing were significantly changed in expression by aLTA- or pLTA-stimulation, including cyclophilin A, HLA-B27, D-dopachrome tautomerase, Mn- SOD, hnRNP-C, PSF and KSRP. These data demonstrated that aLTA and pLTA had different effects on the protein profile of THP-1 cells. Comparison of the proteome alterations will provide candidate biomarkers for further investigation of the immunomodulatory effects of aLTA and pLTA, and the involvement of aLTA in the pathogenesis of Staphylococcus aureus sepsis.

Transition state analogue structures of human phosphoglycerate kinase establish the importance of charge balance in catalysis

Transition state analogue (TSA) complexes formed by phosphoglycerate kinase (PGK) have been used to test the hypothesis that balancing of charge within the transition state dominates enzyme-catalyzed phosphoryl transfer. High-resolution structures of trifluoromagnesate (MgF(3)(-)) and tetrafluoroaluminate (AlF(4)(-)) complexes of PGK have been determined using X-ray crystallography and (19)F-based NMR methods, revealing the nature of the catalytically relevant state of this archetypal metabolic kinase. Importantly, the side chain of K219, which coordinates the alpha-phosphate group in previous ground state structures, is sequestered into coordinating the metal fluoride, thereby creating a charge environment complementary to the transferring phosphoryl group. In line with the dominance of charge balance in transition state organization, the substitution K219A induces a corresponding reduction in charge in the bound aluminum fluoride species, which changes to a trifluoroaluminate (AlF(3)(0)) complex. The AlF(3)(0) moiety retains the octahedral geometry observed within AlF(4)(-) TSA complexes, which endorses the proposal that some of the widely reported trigonal AlF(3)(0) complexes of phosphoryl transfer enzymes may have been misassigned and in reality contain MgF(3)(-).

Perfusion CT in squamous cell carcinoma of the upper aerodigestive tract: long-term predictive value of baseline perfusion CT measurements

BACKGROUND AND PURPOSE

PCT studies hold short-term predictive value in patients treated with chemoradiotherapy. Our aim was to examine the long-term predictive value of baseline PCT studies for local tumor control and overall survival in SCCA of the upper aerodigestive tract treated with chemoradiotherapy.

MATERIALS AND METHODS

Eighty-four patients with advanced SCCA underwent PCT followed by concomitant chemoradiation. The acquired perfusion maps represented BF, BV, MTT, and PS. Visual analysis of the parametric maps for identification of tumor perfusion patterns was conducted. ROC curves, t tests, and Kaplan-Meier survival curves were plotted for local disease control and overall survival.

RESULTS

The median time of local tumor control was 24 months. The BF and PS values were significantly higher in patients who had no recurrence than in those with local failure (P < or = .02). The BF and PS were predictive (P < or = .0006) but BV and MTT held no significant predictive values for local tumor control. The patients with high BF and PS had a longer local tumor control than the patients with hypoperfused tumors (P = .0007). A visually detected BF-BV mismatch had a sensitivity/specificity of 63%/66% (P = .03) and 59%/69% (P = .03) for local tumor control and OS, respectively. Patients without mismatch lived significantly longer than patients with mismatch (P = .01).

CONCLUSIONS

BF, PS, and mismatch of BF-BV are significant predictors of local tumor control after chemoradiation in SCCA of the upper aerodigestive tract.

The association between hypoxia inducible factor-1alpha gene polymorphisms and increased susceptibility to oral cancer

The aim of this study was to estimate the relations between hypoxia inducible factor-1alpha (HIF-1alpha) gene polymorphisms, C1772T and G1790A, to the susceptibility and clinicopathological status of oral cancer. A total of 521 subjects, including 347 controls and 174 oral cancer patients, were recruited in this study and subjected to polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) to analyze the impact of these two polymorphic variants on oral cancer. A significant association between oral cancer susceptibility and G1790A polymorphism was demonstrated since individuals with heterozygotes, that is GA, had a higher risk for oral cancer, compared to GG genotypes after adjusting for other confounders (AOR=3.31; 95%CI=1.27-8.61). Compared to individuals with both C1772C and G1790G homozygotes, individuals with at least one of either C1772T or G1790A of HIF-1alpha gene had a risk of 2.17-folds (95% CI=1.0-4.75) to develop oral cancer. Moreover, results also revealed the presence of synergistic effect between gene polymorphisms of HIF-1alpha and environmental risk factors, such as tobacco and betel nut consumptions while there was no significant association between HIF-1alpha gene polymorphism and clinicopathological parameters of oral cancer. Genetic polymorphism, including C1772T and G1790A, of HIF-1alpha is an important factor for the susceptibility to oral cancer.