Front Cover

Redox and Cancer Part A

Copyright

Contents

Contributors

Preface

Chapter One: Reactive Oxygen Species in Normal and Tumor Stem Cells

1. Introduction

2. ROS

2.1. Common biological ROS

2.2. Sources of ROS

2.2.1. Mitochondria

2.2.2. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs)

2.2.3. Other sources

2.3. Antioxidants and antioxidant enzymes

2.3.1. Cellular antioxidants

2.3.2. SOD and catalase

2.3.3. GSH

2.3.4. Trx

2.3.5. Coordinate regulation of intracellular redox environment

3. ROS and Normal Stem Cells

3.1. Types of major normal stem cells

3.1.1. ESCs

3.1.2. ASCs

3.2. Role of ROS in stem cell physiology

3.2.1. ROS and stem cells

3.2.2. Hypoxia and metabolism of stem cells

3.2.3. Regulation of ROS production in stem cells

3.2.4. Cellular sources of ROS in stem cells

3.3. Role of ROS in stem cell pathology

3.3.1. ROS and stem cell differentiation

3.3.2. ROS and stem cell senescence

3.3.3. ROS and stem cell apoptosis

4. ROS and TSCS

4.1. TSCs

4.2. ROS and LSCs

4.3. ROS and CSCs

5. Conclusion

Acknowledgments

References

Chapter Two: Emerging Regulatory Paradigms in Glutathione Metabolism

1. Introduction

2. Glutathione Homeostasis

2.1. Glutathione biosynthesis

2.1.1. Glutamate cysteine ligase

2.1.2. Redox regulation

2.1.3. Phosphorylation

2.1.4. Proteolysis

2.1.5. Lipid adducts

2.1.6. Glycation

2.2. Glutathione synthetase

2.3. GSH in development

2.4. GSH and cancer

3. Glutathione Salvage

3.1. γ-Glutamyltranspeptidase

3.2. γ-Glutamylcyclotransferase

3.3. 5-Oxoprolinase

4. Precursor Availability

4.1. Glutamate/glutamine

4.2. Cysteine

4.3. Glycine

5. Remaining Questions and Emerging Pathways

5.1. 5-Oxoproline

5.2. ChaC1

5.3. Additional functions of γ-glutamylcysteine and glutathione

6. Summary

Acknowledgment

References

Chapter Three: Gamma-Glutamyl Transpeptidase: Redox Regulation and Drug Resistance

1. Introduction

2. Expression of GGT and Drug Resistance in Human Tumors

3. Structure of GGT

4. Biochemistry of GGT-Catalyzed Reactions

5. Function of GGT

5.1. In normal tissues and in tumors

5.2. Other GGT substrates

5.3. Other GGT genes

6. GSH and Cysteine in Redox Regulation

6.1. GSH and intracellular redox regulation

6.2. Increased requirement for GSH for tumors and cells under redox stress

6.3. Replenishment of GSH is dependent on cysteine and cystine uptake

7. The Role of GGT in Enhancing Cysteine Availability and Drug Resistance

8. Redox Regulation of GGT

8.1. Redox regulation of GGT expression in rats

8.2. Redox regulation of GGT expression in mice

8.3. Redox regulation of GGT expression in humans

8.4. GGT activity in serum

9. Overcoming Resistance to Prooxidant Anticancer Therapy by Inhibiting GGT

9.1. GGT inhibitors

10. Summary

Acknowledgments

References

Chapter Four: Pleiotropic Functions of Glutathione S-Transferase P

1. Introduction

2. Subcellular Distribution of GSTP

3. GST Regulation of Kinase Signaling Pathways

4. GSTP in Redox Regulation and S-Glutathionylation

5. S-Glutathionylation Reactions

6. S-Glutathionylase Active Proteins

7. Deglutathionylase Active Proteins

8. GSTP, Nitric Oxide Synthases, and NO Homeostasis

9. GSTP Binding of Nitric Oxide Carriers

10. GSTP-Mediated Site-Specific Protein Nitrosylation/Glutathionylation

11. GSTP Polymorphisms and Pharmacogenetics

12. GSH Pathways and GSTP as Drug Platforms

13. Conclusions and Perspectives

Acknowledgments

References

Chapter Five: A Comparison of Reversible Versus Irreversible Protein Glutathionylation

1. Introduction

2. Reversible Protein Glutathionylation Reactions

3. Irreversible Glutathionylation

4. 2,3-Dehydroalanine and 2,3-Didehydrobutyrine Formation in Enzyme-Catalyzed Reactions

5. Historical Characterization of Dehydropeptides

6. Examples of Enzyme-Catalyzed Formation of Dehydroamino Acids in Peptide Linkage

7. Nonenzymatic Methods for the Introduction of DHA Residues into Glutathione and Proteins

8. Reducible Glutathionylation of Lens Proteins

9. Irreversible, Nonreducible Glutathionylation of Lens Proteins

10. Nonreducible Glutathionylation Involving Covalent Tethering

11. Conclusions

Acknowledgments

References

Chapter Six: Glutathione Transferases in the Bioactivation of Azathioprine

1. Preamble

2. Background

2.1. Azathioprine

2.2. Glutathione

2.3. Glutathione transferases

2.3.1. Function

2.3.2. Structure

2.3.3. Mechanism of catalysis

2.3.4. Tissue distribution of human GSTs

2.3.5. Biomarker applications

3. Polymorphisms

3.1. Genetic polymorphism of human GST A2-2

3.2. Phenotypic differences in expression of different GST genotypes

3.3. Thermal inactivation of allelic GST 2-2 variants

4. Azathioprine and Immunosuppression

4.1. Azathioprine and inflammatory bowel disease

4.1.1. Thiopurine treatment

4.1.2. Monoclonal antibodies

4.1.3. Bioavailability and activation of azathioprine

4.2. Azathioprine metabolism

4.2.1. Activation

4.2.2. Cytotoxicity

4.2.3. Inactivation

4.2.4. Purine starvation

4.2.5. Other 6-MP metabolites

4.2.6. Changes in metabolite levels

4.2.7. Metabolite concentration thresholds

4.2.8. Cellular signaling

4.2.9. Glutathione conjugation

5. Adverse Effects of Azathioprine

5.1. Dose adjustment

5.2. Various adverse effects

5.3. Cancer

5.4. Selectivity

6. Polymorphisms in the Metabolic Pathways of Azathioprine

6.1. Clinical observations

6.2. GST polymorphism

6.2.1. Kinetic characterization of allelic GST A2-2 variants

6.2.2. Characterization of GST A2-2 using alternative substrates

6.2.3. Structural comparison of A2*C and A2*E

6.2.4. Combining activity and expression in different tissues

6.2.5. Interindividual variations of activity and expression

6.3. TPMT polymorphism

6.4. ITPA polymorphism

6.5. Polymorphism in transporters

6.6. XO and AO polymorphisms

6.7. Rac1 polymorphism

6.8. Polymorphism summary

7. Structural Requirements for High GST Activity with Azathioprine

7.1. Chimeric GST variants obtained by DNA shuffling of homologous sequences

7.2. Stochastic chimeragenesis

7.3. Sequence analysis

7.4. Structure–activity relationships

7.5. Some H-site residues conserved among the active chimeric mutants

7.6. Other segments of interest

7.7. Structural interpretation

7.8. An example of an active GST lacking C-terminal amino acid 222

8. Rational Design of Chimeras

8.1. Strategy

8.2. Design of chimeric GSTs with flanking N- and C-terminal sequences from GST A2-2

8.3. Characterization of the designed chimeras

9. Saturation Mutagenesis of two H-Site Residues in the C-Terminal Region

9.1. Synthesis of mutant library

9.2. Screening and mutant characterization

10. Redesign of GST A2-2 for Enhanced Azathioprine Activity

10.1. Targeted H-site residues

10.2. Mutant library based on reduced codon sets

10.3. Kinetic characterization of mutants isolated

10.4. Comparison with other alpha class sequences

10.5. Structural comparisons

10.5.1. Comparison of GST A1-1, A2*C, and GDH

10.5.2. Three mutated positions

10.5.3. Other positions involved

11. Concluding Remarks

Acknowledgments

References

Chapter Seven: Thioredoxin and Hematologic Malignancies

1. Overview of Thioredoxin

1.1. Historic overview

1.2. Members in Trx system

1.3. Animal models

1.4. Induction, translocation, and secretion of Trx1

1.5. Functions of Trx

1.5.1. Functions of Trx inside the cell

1.5.1.1. Anti-inflammation

1.5.1.2. Antiapoptosis

1.5.1.3. Transcription factor regulation

1.5.2. Functions of Trx outside the cell (cytokine or chemokine-like effects)

2. Thioredoxin in Hematologic Malignancies and Other Cancers

2.1. Trx expression is upregulated in solid tumors and hematologic malignancies

2.2. Trx stimulates cancer cell growth and protects cancer cells from apoptosis

2.3. Trx confers cancer cell drug resistance

2.4. Trx constitutes an important component of tumor cell microenvironment

2.5. Development of Trx1 inhibitors for the treatment of cancer

2.6. Trx2 and cancer treatment

3. Thioredoxin in Hematopoiesis

4. Closing Remarks

Acknowledgments

References

Chapter Eight: Role of the Keap1–Nrf2 Pathway in Cancer

1. Introduction

2. The Keap1–Nrf2 pathway

2.1. Keap1-dependent regulation of Nrf2

2.2. Keap1-independent regulation of Nrf2

3. Dual roles of Nrf2 in cancer

3.1. The role of oxidative stress in cancer

3.2. The use of the Keap1–Nrf2-inducing compounds in chemoprevention

3.3. Oncogenic role of Nrf2

3.4. Mechanisms of Nrf2 overactivity in cancer

3.4.1. Disrupted protein–protein interaction of Keap1–Nrf2

3.4.2. Imbalance in expression levels

3.5. Consequences of Nrf2 hyperactivity

3.5.1. Chemo- and radioresistance

3.5.2. Inhibition of cancer cell apoptosis

3.5.3. Cancer cell proliferation through metabolic reprogramming

3.5.4. The role of Nrf2 in angiogenesis

4. Applications of the Keap1–Nrf2 system in cancer treatment

4.1. Nrf2 as a prognostic marker of cancer

4.2. Enhancing chemo- and radiotherapy with small molecular compounds

4.3. Taking advantage of high Nrf2 activity: Nrf2-regulated lentiviral suicide gene therapy and the use of bioreductive p...

5. Concluding Remarks and Future Perspectives

Acknowledgments

References

Index

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