Aldehyde dehydrogenases and their role in carcinogenesis

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Aldehydes are reactive molecules from various sources, with both beneficial (e.g., vision) and harmful (e.g., cytotoxicity, mutagenicity) biological effects.
• Aldehyde dehydrogenases (ALDHs) are a family of NADP-dependent enzymes that detoxify aldehydes by oxidizing them to carboxylic acids.
• Mammalian ALDHs are classified into three main groups (1, 2, and 3), with diverse expression patterns and substrate specificities.

Purpose of the Study:

• To review the role of aldehyde dehydrogenases (ALDHs) in biological systems and their specific involvement in carcinogenesis.
• To discuss the structural and functional properties of mammalian ALDHs and their interrelationships.
• To explore the changes in ALDH expression during tumorigenesis and their potential implications.

Main Methods:

• Analysis of primary sequence to classify mammalian aldehyde dehydrogenases (ALDHs).
• Review of existing literature on ALDH structure, function, and expression patterns.
• Examination of ALDH activity changes in experimental carcinogenesis models and human tumors.

Main Results:

• ALDHs are essential for metabolizing a wide range of endogenous and exogenous aldehydes.
• Alterations in ALDH activity, particularly the induction of class 3 ALDH, are observed early in carcinogenesis and are associated with preneoplastic cells.
• Changes in ALDH gene expression are permanent and occur during tumor development.

Conclusions:

• ALDHs play a critical role in protecting against aldehyde-induced toxicity and are implicated in cancer development.
• Specific changes in ALDH expression patterns are early events in tumorigenesis, potentially marking preneoplastic lesions.
• Modulating ALDH activity may be a key factor in the efficacy of certain chemotherapeutic agents, such as cyclophosphamide analogs.