Expression pattern, ethanol-metabolizing activities, and cellular localization of alcohol and aldehyde dehydrogenases in human pancreas: implications for pathogenesis of alcohol-induced pancreatic injury.
BACKGROUND
Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are major enzymes responsible for metabolism of ethanol. Genetic polymorphisms of ADH1B, ADH1C, and ALDH2 occur among racial populations. The metabolic effect and metabolites contribute to pathogenesis of pancreatic injury. The goal of this study was to determine the functional expressions and cellular localization of ADH and ALDH families in human pancreas.


METHODS
Fifty five surgical specimens of normal pancreas as well as 15 samples each for chronic pancreatitis and pancreatic cancer from archival formalin-fixed paraffin-embedded tissue specimens were investigated. Class-specific antibodies were prepared by affinity chromatographies from rabbit antisera raised against recombinant human ADH1C1, ADH4, ADH5, ADH7, ALDH1A1, ALDH2, and ALDH3A1. The isozyme expression patterns of ADH/ALDH were identified by isoelectric focusing, and the activities were assayed spectrophotometrically. The protein contents of ADH/ALDH isozymes were determined by immunoblotting, and the cellular localizations were detected by immunohistochemistry and histochemistry.


RESULTS
At 33 mM ethanol, pH 7.5, the activities were significantly different between allelic phenotypes of ADH1B. The activity of ALDH2-inactive phenotypes was slightly lower than ALDH2-active phenotypes at 200 microM acetaldehyde. The protein contents were in the following decreasing order: ALDH1A1, ALDH2, ADH1, and ADH5. ADH1B was detected in the acinar cells and ADH1C in the ductular, islet, and stellate cells. The expression of ADH1C appeared to be increased in the activated pancreatic stellate cells in chronic pancreatitis and pancreatic cancer.


CONCLUSIONS
Alcohol dehydrogenase and ALDH family members are differentially expressed in the various cell types of pancreas. ADH1C may play an important role in modulation of activation of pancreatic stellate cells.
Chiang
Chien-Ping
CP
The Graduate Institute of Medical Sciences, and Department of Biochemistry, National Defense Medical Center, 161 Minchuan East Road Section 6, Taipei, Taiwan.
Wu
Chew-Wun
CW
Lee
Shiao-Pieng
SP
Chung
Chia-Chi
CC
Wang
Chi-Wei
CW
Lee
Shou-Lun
SL
Nieh
Shin
S
Yin
Shih-Jiun
SJ
D000328:Adult; D000368:Aged; D000426:Alcohol Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D000444:Aldehyde Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D000071396:Aldehyde Dehydrogenase, Mitochondrial; D002492:Central Nervous System Depressants / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation; D005838:Genotype; D055166:Hepatic Stellate Cells / Q000166:cytology / Q000201:enzymology / Q000473:pathology; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000166:cytology / Q000201:enzymology* / Q000473:pathology; D010190:Pancreatic Neoplasms / Q000201:enzymology* / Q000473:pathology; D010195:Pancreatitis / Q000201:enzymology* / Q000473:pathology; D010641:Phenotype
D002492:Central Nervous System Depressants; D007527:Isoenzymes; D000431:Ethanol; C489332:ADH1B protein, human; C420272:ADH1C protein, human; D000426:Alcohol Dehydrogenase; C096127:ALDH2 protein, human; D000444:Aldehyde Dehydrogenase; D000071396:Aldehyde Dehydrogenase, Mitochondrial