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Aldehyde dehydrogenase in 2-acetamidofluorene-induced rat hepatomas. Ontogeny and evidence that the new isoenzymes are not due to normal gene de-repression.

ABSTRACT: The pre- and post-natal ontogeny of Sprague-Dawley rat liver aldehyde dehydrogenase [aldehyde-NAD(P)(+) oxidoreductase, EC 1.2.1.5] is described. At no time in its ontogenetic development does normal liver aldehyde dehydrogenase exhibit any of the characteristics of a series of unique aldehyde dehydrogenases that can be isolated from 2-acetamidofluorene-induced rat hepatomas. Enzyme activity is first detectable in 15-day foetal liver and gradually increases throughout pre- and post-natal development until adult activities are attained by day 49 after birth. Electrophoretically, normal aldehyde dehydrogenase, throughout its ontogeny, exists as the same single isoenzyme found in normal adult liver. Isoelectric points for two normal liver isoenzymes demonstrable by isoelectric focusing are pH5.9 and 6.0. The immunochemical properties of aldehyde dehydrogenase during its ontogeny are identical with those of normal adult liver aldehyde dehydrogenase when tested against anti-(hepatoma aldehyde dehydrogenase) serum in Ouchterlony double-diffusion tests. The results indicate that the hepatoma-specific aldehyde dehydrogenases are not the result of the de-repression of genes normally repressed in adult rat liver or in some other adult tissue.

SUBMITTER: Lindahl R

PROVIDER: S-EPMC1164764 | biostudies-other | 1977 Apr

REPOSITORIES: biostudies-other

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Project description:BACKGROUND: We showed there are specific ALDH1 autoantibodies in ovarian autoimmune disease and ovarian cancer, suggesting a role for ALDH1 in ovarian pathology. However, there is little information on the ovarian expression of ALDH1. Therefore, we compared ALDH1 expression in normal ovary and benign and malignant ovarian tumors to determine if ALDH1 expression is altered in ovarian cancer. Since there is also recent interest in ALDH1 as a cancer stem cell (CSC) marker, we assessed co-expression of ALDH1 with CSC markers in order to determine if ALDH1 is a potential CSC marker in ovarian cancer. METHODS: mRNA and protein expression were compared in normal human ovary and serous ovarian tumors using quantitative Reverse-Transcriptase PCR, Western blot (WB) and semi-quantitative immunohistochemistry (IHC). ALDH1 enzyme activity was confirmed in primary ovarian cells by flow cytometry (FC) using ALDEFLUOR assay. RESULTS: ALDH1 mRNA expression was significantly reduced (p < 0.01; n = 5) in malignant tumors compared to normal ovaries and benign tumors. The proportion of ALDH1+ cells was significantly lower in malignant tumors (17.1 ± 7.61%; n = 5) compared to normal ovaries (37.4 ± 5.4%; p < 0.01; n = 5) and benign tumors (31.03 ± 6.68%; p < 0.05; n = 5). ALDH1+ cells occurred in the stroma and surface epithelium in normal ovary and benign tumors, although surface epithelial expression varied more in benign tumors. Localization of ALDH1 was heterogeneous in malignant tumor cells and little ALDH1 expression occurred in poorly differentiated malignant tumors. In benign tumors the distribution of ALDH1 had features of both normal ovary and malignant tumors. ALDH1 protein expression assessed by IHC, WB and FC was positively correlated (p < 0.01). ALDH1 did not appear to be co-expressed with the CSC markers CD44, CD117 and CD133 by IHC. CONCLUSIONS: Total ALDH1 expression is significantly reduced in malignant ovarian tumors while it is relatively unchanged in benign tumors compared to normal ovary. Thus, ALDH1 expression in the ovary does not appear to be similar to breast, lung or colon cancer suggesting possible functional differences in these cancers. SIGNIFICANCE: These observations suggest that reduced ALDH1 expression is associated with malignant transformation in ovarian cancer and provides a basis for further study of the mechanism of ALDH1 in this process.

Project description:IntroductionAlthough estrogen and progesterone play a key role in normal mammary development and in breast cancer, the potential for proliferation and lineage differentiation as well as origin of cells that express the estrogen receptor (ER) in normal breast epithelium are not known. Some evidence suggests that normal human mammary stem/progenitor cells are ER-, but the identity of these cells and the cellular hierarchy of breast epithelium are still subjects of controversy. It is likely that elucidation of these aspects will bring insight into the cellular origin of breast cancer subtypes.MethodsWe used fluorescence-activated cell sorting of primary human mammary epithelial cells along with in vitro and in vivo functional assays to examine the hierarchic relation between cells with aldehyde dehydrogenase enzymatic activity (ALDH+ cells) and ER+ cells in the normal human breast epithelium. We assessed the proliferation and lineage differentiation potential of these cells in vitro and in vivo. A gene reporter assay was used to separate live ER+ and ER- mammary epithelial cells. With shRNA-mediated knockdown, we investigated the role of ALDH isoforms in the functionality of mammary epithelial progenitor cells.ResultsWe describe a cellular hierarchy in the normal human mammary gland in which ER-/ALDH+ cells with functional properties of stem/progenitor cells generate ER+ progenitor cells, which in turn give rise to cells of luminal lineage. We show that the ALDH1A1 isoform, through its function in the retinoic acid metabolism, affects the proliferation and/or early differentiation of stem/progenitor cells and is important for branching morphogenesis.ConclusionsThis study presents direct evidence that ER+ cells are generated by ER-/ALDH+ stem/progenitor cells. We also show that ER+ cells are able to generate cell progeny of luminal lineage in vitro and in vivo. Loss of ALDH1A1 function impairs this process, as well as branching morphogenesis and clonogenicity in suspension culture. This latter effect is reversed by treatment with retinoic acid.

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Aldehyde dehydrogenase in 2-acetamidofluorene-induced rat hepatomas. Ontogeny and evidence that the new isoenzymes are not due to normal gene de-repression.

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