Preface



The dehydrogenases are NAD(P)H/NAD(P)+-dependent oxidoreductases with different functions in the cells and with different substrates. They are present in human, plant and micro-organism tissues, and are of enormous biochemical interest. They are associated with both catabolic and anabolic pathways linked to normal functioning and homeostasis. The book does not aim to examine all these enzymes, but to take into consideration only a small number of them.

#### XII Preface

ALDH is an important marker for identifying stem cells, especially cancer stem cells. ALDH Bright (ALDHbr) cells are derived from different tissues expressing high ALDH activity and that have progenitor cell activity. Studies have shown that ALDHbr populations may be useful in several cell therapy applications: thus the ALDHbr population may play an important role in regenerative medicine, and could become a new therapeutic target in cancer studies.

Preface XI

indications of possible success in targeting the PDH complex further suggest that targeting other cancer-central dehydrogenases might add to the chemotherapeutic armamentarium. Collectively and most generally, these observations indicate that targeting the *mitochondrial* features of tumor-specific metabolism may be especially






associated with depletion of TCA cycle intermediates and cellular acidosis.

effective in therapeutic targeting of cancer cells.

tryptophan, and asparagines.

in the liver.

mediator of hyperammonemic neurotoxicity.



X Preface

new therapeutic target in cancer studies.

linked with differences in variants of the disease

ALDH is an important marker for identifying stem cells, especially cancer stem cells. ALDH Bright (ALDHbr) cells are derived from different tissues expressing high ALDH activity and that have progenitor cell activity. Studies have shown that ALDHbr populations may be useful in several cell therapy applications: thus the ALDHbr population may play an important role in regenerative medicine, and could become a







#### XIV Preface

gradient across the mitochondrial inner membrane, allowing for the synthesis of ATP. Alternatively, electrons can be diverted to reduce the ubiquinone pool, and provide reducing equivalents necessary to reduce superoxide anions, originating either from an exogenous source or from the respiratory chain itself. Deficiencies in TCA cycle enzymes have been shown to cause a wide spectrum of human diseases: Encephalopathy (Leigh syndrome), pheochromocytoma and paraganglioma.

Considering the importance of the dehydrogenases taken into consideration, the book is divided in three chapters:


I thank Dr. Marina Maggiora and Dr. Elena Paiuzzi for their help in reviewing the articles.

> **Rosa Angela Canuto** Dept. of Experimental Medicine and Oncology, University of Turin, Italy

**Section 1** 

**Dehydrogenases and Cancer** 

**Chapter 1** 

© 2012 Allahverdiyev et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Aldehyde Dehydrogenase:** 

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/48591

**1. Introduction** 

Adil M. Allahverdiyev, Malahat Bagirova, Olga Nehir Oztel, Serkan Yaman, Emrah Sefik Abamor, Rabia Cakir Koc, Sezen Canim Ates, Serhat Elcicek and Serap Yesilkir Baydar

with some even found in more than one location (Marchitti*, et al.*, 2008).

Aldehyde dehydrogenases (ALDH) belong to the oxidoreductase family, which catalyze the conversion of aldehydes to their corresponding acids. As a group of NAD(P)+-dependent enzymes, aldehyde dehydrogenases (ALDHs) are involved in oxidation of a large number of aldehydes into their weak carboxylic acids (Moreb*, et al.*, 2012). ALDH is found in every subcellular region such as cytosol, endoplasmic reticulum, mitochondria, and the nucleus,

ALDH is also found in stem cells. During early life and growth, stem cells **(**SCs) have a spectacular potential to develop into several cell types in the body. In many tissues, SCs behave as a kind of internal repair system, dividing essentially without limit to replenish other cells (Fuchs & Segre, 2000). Stem cells are distinguished from other cell types by two important characteristics: (1) Their unspecialized properties and renewal potencies; and (2) differentiation into other cell types under certain physiologic or experimental conditions (Discher*, et al.*, 2009, Solis*, et al.*, 2012). These cells are identified by their expression of a particular panel of surface molecules, with the presence of CD73, CD90, CD105, and the absence of CD14, CD34, CD45, and HLA-DR. They show no proliferative response from alloreactive lymphocytes because of the negligible levels of extracellular MHC class I and II determinants and they also have important immunomodulatory functions in all the cells involved in both the innate and adaptive immune responses (Nauta & Fibbe, 2007). On the other hand, cancer stem cell theory is supported by biological reason for aging. The theory postulates that cancer SCs, a small subset of tumor cells also have stem cell-like properties (epithelial-to-mesenchymal progression, differentiation and self-renewing capacity). ALDH expression has demonstrated itself to be a possibly relevant prognostic marker. For this

**Cancer and Stem Cells** 
