Aldehyde dehydrogenase isoenzymes in tumours--assay with possible prognostic value for oxazaphosphorine chemotherapy.
A novel fluorimetric assay, allowing independent measurement of the activities of two principal cytosolic forms of human aldehyde dehydrogenase, ALDH-1 and ALDH-3 (known as a tumour-associated ALDH) was applied to estimate the activities of these isoenzymes in human liver and thyroid tumours. The assay is based on two artificial substrates, 6-methoxy-2-naphthaldehyde (MONAL-62) and 7-methoxy-1-naphthaldehyde (MONAL-71), exhibiting excellent substrate properties toward various forms of human ALDH (see Wierzchowski et al., 1997, Anal. Biochem. 245, 69-78). We have found significant differences in ALDH activities between malignant and non-malignant tissue fragments, particularly in cancerous livers. Out of 16 tumours examined, only 4 exhibited ALDH-1 activities comparable to that found in the tumour-free tissue (0.5-2.5 U/g), while in the remaining 12 this activity was at least 10-fold lower. The ALDH-3 activity was detectable in about 40% of both tumour and tumour-free liver samples (maximum value 1.5 U/g). Comparison of 13 pathological thyroid fragments revealed ALDH activities in the range of 0.02 to 0.35 U/g, with two malignant samples showing activities of 0.27 and 0.18 U/g. Both substrate specificity and kinetic behaviour of the thyroid ALDH (Km values for the fluorogenic naphthaldehydes as well as propanal inhibition profile) were similar to those of the purified ALDH-1. In 5 thyroid samples traces of ALDH-3 activity was detected, using MONAL-62 and NADP+ as substrates (maximum value 0.04 U/g). Possible prognostic value of the foregoing measurements for cyclophosphamide chemotherapy is discussed.
Department of Physical Chemistry, Faculty of Pharmacy, Warsaw, Poland. wropio@farm.am-waw.edu.pl
P
P
Wroczyński
A
A
Laskowska
J
J
Wierzchowski
A
A
Szubert
J
J
Polański
M
M
Słowiaczek
D000444:Aldehyde Dehydrogenase / Q000032:analysis*; D000080924:Aldehyde Dehydrogenase 1 Family; D005470:Fluorometry; D006801:Humans; D007527:Isoenzymes / Q000032:analysis*; D007700:Kinetics; D008113:Liver Neoplasms / Q000201:enzymology*; D011379:Prognosis; D050697:Retinal Dehydrogenase; D013379:Substrate Specificity; D013964:Thyroid Neoplasms / Q000201:enzymology*
D007527:Isoenzymes; C030863:corneal protein 54, bovine; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C510223:ALDH1A1 protein, human; D050697:Retinal Dehydrogenase