Doris Meier-Tackmann

Distribution of ADH2 and ALDH2 genotypes in different populations

SummaryThe distribution of the human liver alcohol dehydrogenase, ADH2, and aldehyde dehydrogenase, ALDH2, genotypes in 21 different populations comprising Mongoloids, Caucasoids, and Negroids was determined by hybridization of the amplified genomic DNA with allele-specific oligonucleotide probes. Whereas the frequency of the ADH12allele was found to be relatively high in the Caucasoids, Mexican Mestizos, Brazilian Indios, Swedish Lapps, Papua New Guineans and Negroids, the frequency of the ADH22gene was considerably higher in the Mongoloids and Australian Aborigines. The atypical ALDH2 gene (ALDH22) was found to be extremely rare in Caucasoids, Negroids, Papua New Guineans, Australian Aborigines and Aurocanians (South Chile). In contrast, this mutant gene was found to be widely prevalent among the Mongoloids. Individuals possessing the abnormal ALDH2 gene show alcohol-related sensitivity responses (e.g. facial flushing), have the tendency not to be habitual drinkers, and apparently suffer less from alcoholism and alcohol-related liver disease.

Detoxification of cyclophosphamide by human aldehyde dehydrogenase isozymes

In in vitro studies, no turnover of aldophosphamide and mafosfamide was observed with the tumor-specific aldehyde dehydrogenase 3 isozyme (ALDH3) isolated from human stomach mucosa as well as from lung (A549) and pharynx (UMSCC2) carcinoma cell lines. Only the human liver cytosolic ALDH preparation (ALDH1) showed any significant oxidation of aldophosphamide and mafosfamide.

Human liver aldehyde dehydrogenase: subcellular distribution in alcoholics and nonalcoholics.

Activity assay and isoelectric focusing analysis of human biopsy and autopsy liver specimens showed the existence of two major aldehyde dehydrogenases (ALDH I, ALDH II). Subcellular distribution of these isozymes was determined in autopsy livers from alcoholics and nonalcoholics. Nearly 70% of the total ALDH activity was recovered in the cytosol which contained both the major isozymes. Densitometric evaluation of isozyme bands showed that about 65% of the cytosolic enzyme activity was due to ALDH II and the rest due to ALDH I isozyme. Only about 5% of the total ALDH activity was found in the mitochondrial fraction (70% ALDH I and 30% ALDH II). Significantly reduced total and specific ALDH activities were noted in all the subcellular fractions from cirrhotic liver specimens. Apparently, ALDH I isozyme from cytosol and mitochondria is primarily responsible for the oxidation of small amounts of acetaldehyde normally found in the blood of nonalcoholics after drinking moderate amounts of alcohol. However, in alcoholics who exhibit higher blood acetaldehyde concentrations after drinking alcohol, ALDH II isozyme may be of greater physiological significance.

Effect of acute ethanol drinking on alcohol metabolism in subjects with different ADH and ALDH genotypes.

The effect of different amounts of orally ingested ethanol on plasma alcohol dehydrogenase (ADH) and erythrocyte aldehyde dehydrogenase (ALDH), as well as on the blood ethanol and acetaldehyde levels, was examined in healthy nonalcoholic subjects. The genotypes at ADH2 and ALDH2 locus were identified in enzymatically amplified blood DNA by hybridization with allele-specific oligonucleotides. While the Japanese subject was found to be genotypically heterozygous for both ADH2 and ALDH2, the Caucasian subjects were genotypically homozygous normal for these alleles. A faster ethanol elimination associated with a higher blood acetaldehyde level was observed in the Japanese subject as compared to Caucasian subjects. However, no significant change in ADH and ALDH enzyme activities was detected as the result of acute ethanol intake.

Metabolism of Cyclophosphamide by Aldehyde Dehydrogenases

Cyclophosphamide (Endoxan) and other oxazaphosphorines such as 4-hydroperoxy-cyclophosphamide, ifosfamide, and mafosfamide are widely used as antineoplastic drugs (Sladek, 1988; Lindahl, 1992). The cytotoxic effect is caused by alkylation reaction of these drugs with DNA and proteins inhibiting the cell proliferation. These chemotherapeutic agents are also extensively applied as immunosuppressants during bone marrow transplantation, and in autoimmune diseases. Cyclophosphamide is pharmacologically inactive, and needs to be biotransformed to its cytotoxic metabolite phosphoramide mustard via an intermediate metabolite 4-hydroxycyclophosphamide (Borch et al., 1984; Hill et al., 1973). The latter compound exists in equilibrium with aldophosphamide which can get converted to a non-cytotoxic compound carboxy-phosphamide through irreversible oxidation of the aldehyde group catalyzed by one or more forms of aldehyde dehydrogenases (Hilton et al., 1984; Sladek et al., 1989; Kastan et al, 1990; Dockham et al., 1992; Moreb et al., 1992). This enzymatic pathway leads to the detoxification of cyclophosphamide affecting its therapeutic efficiency. Therefore, induction or overexpression of one or more of the relevant ALDH forms in target cells might primarily account for the cyclophosphamide-specific acquired resistance exhibited by many neoplastic cells.

A search for the indianapolis-variant of human alcohol dehydrogenase in liver autopsy samples from North Germany and Japan

SummaryHuman liver alcohol dehydrogenase (ADH) variants were screened in random autopsy specimens from 53 North German and 34 Japanese individuals. Based on pH-activity profile and electrophoretic pattern, only ADH2 and ADH3 variants were detected. In relatively fresh specimens, an “anodic band” or “π-ADH” band was also observed. The recently reported new molecular forms collectively called “ADHIndianapolis” (Bosron et al. 1980) could not be demonstrated and therefore may be confined hitherto only to the American black population.

Tumor-Associated Aldehyde Dehydrogenase (ALDH3): Expression in Diffrent Human Tumor Cell Lines with and without Treatment with 3-Methylcholanthrene

Many past studies from various laboratories have shown that several isozymes of aldehyde dehydrogenase (ALDH, EC 1.2.1.3) can be induced in animals by various xenobiotics and carcinogens such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene and phenobarbital (Feinstein et al., 1976; Deitrich et al., 1977). In cultures of normal human hepatocytes and human hepatoma cell line Hep G2, the total ALDH activity has been shown to be increased after application of phenobarbital or 3-methylcholanthrene (Marselos et al., 1987).

Aldehyde Dehydrogenase-Mediated Metabolism of Acetaldehyde and Mafosfamide in Blood of Healthy Subjects and Patients with Malignant Lymphoma

Cyclophosphamide (CP) and mafosfamide (MF) are converted in various tissues to 4-hydroxycyclophosphamide, and subsequently to aldophosphamide (AP). In target cells, AP is further broken down to the toxic compounds phosphoramide mustard and acrolein. AP can be oxidized to a nontoxic metabolite (carboxyphosphamide) catalyzed by one or more types of aldehyde dehydrogenase (ALDH) isoenzymes. Thus, intracellular ALDH activity appears to be an important determinant in modulating sensitivity to CP in patients undergoing chemotherapy. The class 1 cytosolic enzyme (ALDH1) has been shown to be particularly important in the metabolism of CP and MF derivatives in bone marrow cells (Kohn and Sladek, 1985; Kastan et al., 1990; Dockham et al., 1992). The overall contribution of blood ALDH in this respect is, however, not known. In the present study, we have determined ALDH activity in human blood subfractions from healthy subjects and malignant lymphoma patients undergoing combination chemotherapy plus or minus CP.

A sensitive bioluminescent assay of alcohol dehydrogenase in human serum and tissue extracts

ConclusionsWith the aid of a sensitive bioluminescence assay, alcohol dehydrogenase activity can be measured in the plasma of chronic alcoholics and patients with other drug-related liver-disorders. Suitable reagents for the assay are commercially available but must be compared regarding sensitivity and stability before routine determinations are introduced in clinical practice.

Changes in Aldehyde Dehydrogenase Isozymes Expression in Long-Term Cultures of Human Hematopoietic Progenitor Cells

Oxazaphosphorines (e.g., 4-hydroperoxycyclophosphamide (4-HC), mafosfamide, ifosfamide) are commonly used to purge malignant blood cells from autologous bone marrow samples before reinfusion (Beran et al., 1987; Yeager et al., 1990; Carlo-Stella et al., 1994). Recently published studies from many laboratories including our own have unequivocally established that there is an associative as well as causative inverse relationship between cellular content of ALDH — whether of normal or malignant cell origin — and sensitivity to oxazaphosphorines (Kohn et al., 1987; Russo and Hilton, 1988; von Eitzen et al., 1994; Agarwal et al., 1995; Sreerama and Sladek, 1995; Sladek et al., 1995; Moreb et al., 1995). Until now, only class 1 (ALDH1 and ALDH2) and class 3 (ALDH3) isozymes (constitutive and inducible forms) have been implicated in the detoxification of cyclophosphamide derivatives such as 4-HC and mafosfamide (Dockham et al., 1992; Bunting and Townsend, 1996).