Aldehyde Dehydrogenase Activity Is a Biomarker of Primitive Normal Human Mammary Luminal Cells

Terry Fox Laboratory, British Columbia Cancer Agency, Vancouver, British Columbia, Canada.
Stem Cells (Impact Factor: 6.52). 02/2012; 30(2):344-8. DOI: 10.1002/stem.1001
Source: PubMed


Elevated aldehyde dehydrogenase (ALDH) expression/activity has been identified as an important biomarker of primitive cells in various normal and malignant human tissues. Here we examined the level and type of ALDH expression and activity in different subsets of phenotypically and functionally defined normal human mammary cells. We find that the most primitive human mammary stem and progenitor cell types with bilineage differentiation potential show low ALDH activity but undergo a marked, selective, and transient upregulation of ALDH activity at the point of commitment to the luminal lineage. This mirrors a corresponding change in transcripts and protein levels of ALDH1A3, an enzyme involved in retinoic acid synthesis and the most highly expressed ALDH gene in normal human mammary tissue. In contrast, ALDH1A1 is expressed at low levels in all mammary epithelial cells. These findings raise interesting questions about the reported association of ALDH activity with breast cancer stem cells and breast cancer prognosis.

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Available from: Nagarajan Kannan, Oct 09, 2014
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    • "To overcome this limitation, we used a luminal breast cancer cell line, MCF7, as a source for ALDH+ and CD44+CD24-breast CSCs since most cell lines contain both CSC fractions [18] [19] [20]. Within the MCF7 cell line, most cells exhibit a mature luminal cell phenotype, CD49f-EpCAM+ [21] [22] [23]. If breast CSCs are more prognostic than bulk cancer cells, the proteins governing stem cell properties are likely to influence clinical outcome. "
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    ABSTRACT: Accumulating evidence has demonstrated that breast cancers are initiated and develop from a small population of stem-like cells termed cancer stem cells (CSCs). These cells are hypothesized to mediate tumor metastasis and contribute to therapeutic resistance. However, the molecular regulatory networks responsible for maintaining CSCs in an undifferentiated state have yet to be elucidated. In this study, we used CSC markers to isolate pure breast CSCs fractions (ALDH+ and CD44+CD24- cell populations) and the mature luminal cells (CD49f-EpCAM+) from the MCF7 cell line. Proteomic analysis was performed on these samples and a total of 3,304 proteins were identified. A label-free quantitative method was applied to analyze differentially expressed proteins. Using the criteria of greater than 2 fold changes and p value < 0.05, 305, 322 and 98 proteins were identified as significantly different in three pairwise comparisons of ALDH+ vs CD44+CD24-, ALDH+ vs CD49f-EpCAM+ and CD44+CD24- vs CD49f-EpCAM+, respectively. Pathway analysis of differentially expressed proteins by Ingenuity Pathway Analysis (IPA) revealed potential molecular regulatory networks that may regulate CSCs. Selected differential proteins were validated by Western blot assay and immunohistochemical staining. The use of proteomics analysis may increase our understanding of the underlying molecular mechanisms of breast CSCs. This may be of importance in the future development of anti-CSC therapeutics. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    Proteomics 09/2015; DOI:10.1002/pmic.201500002 · 3.81 Impact Factor
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    • "Although the exact isoform of ALDH1A responsible for the enzymatic activity assessed by BODIPY aminoacetaldehyde remains controversial [13-16], aldehyde dehydrogenase 1 family member A1 (ALDH1A1) is thought to have a predominant role [17]. Thus, much attention has been focused on the relationship between the expression of this isoform and the clinicopathologic parameters, including prognosis, of breast cancer patients. "
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    ABSTRACT: Background Aldehyde dehydrogenase 1 family member A1 (ALDH1A1) has been identified as a putative cancer stem cell (CSC) marker in breast cancer. However, the clinicopathological and prognostic significance of this protein in breast cancer patients remains controversial. Methods This meta-analysis was conducted to address the above issues using 15 publications covering 921 ALDH1A1+ cases and 2353 controls. The overall and subcategory analyses were performed to detect the association between ALDH1A1 expression and clinicopathological/prognostic parameters in breast cancer patients. Results The overall analysis showed that higher expression of ALDH1A1 is associated with larger tumor size, higher histological grade, greater possibility of lymph node metastasis (LNM), higher level expression of epidermal growth factor receptor 2 (HER2), and lower level expression of estrogen receptor (ER)/progesterone receptor (PR). The prognosis of breast cancer patients with ALDH1A1+ tumors was poorer than that of the ALDH1A1- patients. Although the relationships between ALDH1A1 expression and some clinicopathological parameters (tumor size, LNM, and the expression of HER2) was not definitive to some degree when we performed a subcategory analysis, the predictive values of ALDH1A1 expression for histological grade and survival of breast cancer patients were significant regardless of the different cutoff values of ALDH1A1 expression, the different districts where the patients were located, the different clinical stages of the patients, the difference in antibodies used in the studies, and the surgery status. Conclusions Our results indicate that ALDH1A1 is a biomarker to predict tumor progression and poor survival of breast cancer patients. This marker should be taken into consideration in the development of new diagnostic and therapeutic program for breast cancer.
    BMC Cancer 06/2014; 14(1):444. DOI:10.1186/1471-2407-14-444 · 3.36 Impact Factor
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    • "Both ALDH1A1 and ALDH1A3 have been associated with poor prognosis in breast cancer [12,21-23]. ALDH1A3 was associated with primitive luminal progenitors in normal breast epithelium [24]. "
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    ABSTRACT: Introduction Although 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. Methods We 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. Results We 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. Conclusions This 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.
    Breast cancer research: BCR 05/2014; 16(3):R52. DOI:10.1186/bcr3663 · 5.49 Impact Factor
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