Gene Summary

Gene:ALDH1A1; aldehyde dehydrogenase 1 family member A1
Aliases: ALDC, ALDH1, HEL-9, HEL12, PUMB1, ALDH11, RALDH1, ALDH-E1, HEL-S-53e
Summary:The protein encoded by this gene belongs to the aldehyde dehydrogenase family. Aldehyde dehydrogenase is the next enzyme after alcohol dehydrogenase in the major pathway of alcohol metabolism. There are two major aldehyde dehydrogenase isozymes in the liver, cytosolic and mitochondrial, which are encoded by distinct genes, and can be distinguished by their electrophoretic mobility, kinetic properties, and subcellular localization. This gene encodes the cytosolic isozyme. Studies in mice show that through its role in retinol metabolism, this gene may also be involved in the regulation of the metabolic responses to high-fat diet. [provided by RefSeq, Mar 2011]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:retinal dehydrogenase 1
Source:NCBIAccessed: 15 March, 2017


What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 15 March 2017 using data from PubMed using criteria.

Literature Analysis

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Tag cloud generated 15 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ALDH1A1 (cancer-related)

Senol S, Aydin A, Kosemetin D, et al.
Gastric Adenocarcinoma Biomarker Expression Profiles and their Prognostic Value.
J Environ Pathol Toxicol Oncol. 2016; 35(3):207-222 [PubMed] Related Publications
Expression levels of several molecules implicated in carcinogenesis were examined by immunohistochemical staining, and the prognostic significance of their expression levels in gastric adenocarcinoma (GA) was evaluated. A total of 115 GA and 20 control gastric tissue samples were evaluated by immunohistochemistry using 33 antibodies targeting molecules known to play a part in the development of various tumors. Overexpression of carbonic anhydrase IX (CAIX) and loss of AT-rich interactive domain-containing protein 1A (ARID1A), aldehyde dehydrogenase 1 (ALDH1), and CD44 expression in GA patients were significantly correlated with lymph node (LN) metastasis, advanced tumor stage, and poor prognosis. The results demonstrated that ALDH1A and ARID1A may be strong independent prognostic factors associated with overall survival and recurrence-free survival (p < 0.01 and p < 0.05, respectively). Our results demonstrated that ALDH1, CD44, ARID1A, and CAIX in immunoreactive GA tumor cells exhibit different expression profiles compared with control cells and that these differences are associated with patient survival. The molecules with differential expression profiles were associated with some common functions, including hypoxia, epithelial-to-mesenchymal transition, and SW1/SNF-mediated chromatin remodeling. In addition, the loss of ALDH1, ARID1A, and CD44 and the overexpression of CAIX are important for tumor invasion and metastasis; therefore, they may serve as useful prognostic indicators of long-term survival in patients with GA. In conclusion, our study found that abnormal expression of some of the proteins evaluated in GA tumor cells might have an important role in carcinogenesis and tumor progression and thus may influence the prognosis of patients with GA.

Ikemura S, Aramaki N, Fujii S, et al.
Changes in the tumor microenvironment during lymphatic metastasis of lung squamous cell carcinoma.
Cancer Sci. 2017; 108(1):136-142 [PubMed] Free Access to Full Article Related Publications
Metastasis and growth in neoplastic lesions requires the multistep regulation of microenvironmental factors. We aimed to elucidate the microenvironmental changes in the process of lymphatic metastasis of lung squamous cell carcinoma. We examined the morphological characteristics of 102 cases of primary tumor (PT), 50 of intralymphatic tumor (ILT), 51 of lymph node (LN) micrometastasis (LN-Mic; ≤2 mm in size), and 82 of LN macrometastasis (LN-Mac; ≥10 mm in size). Afterwards we evaluated the expression of nine molecules (epidermal growth factor receptor, fibroblast growth factor receptor 2, CD44, aldehyde dehydrogenase 1, Podoplanin, E-cadherin, S100A4, geminin, and ezrin) in matched PT, ILT, LN-Mic, and LN-Mac from 23 of these cases. The number of smooth muscle actin α-positive fibroblasts, CD34-positive microvessels and CD204-positive macrophages were also examined. As a result, the mitotic index of tumor cells was significantly lower in ILT and LN-Mic than PT and LN-Mac (P < 0.001). Moreover, stromal reaction in ILT and LN-Mic was less prominent than in PT and LN-Mac (P < 0.001). Immunohistochemical study revealed that epidermal growth factor receptor expression level and frequency of geminin-positive cells in ILT and LN-Mic were significantly lower than in PT and LN-Mac (P < 0.05). The number of stromal cells indicated by staining of CD34, CD204, and smooth muscle actin α in ILT and LN-Mic was also significantly lower than in PT and LN-Mac (P < 0.05). In lung squamous cell carcinoma, drastic microenvironmental changes (e.g., growth factor receptor expression and proliferative capacity of tumor cells and structural changes in stromal cells) occur during both the process of lymphatic permeation and the progression into macrometastases.

DA Cruz Paula A, Marques O, Sampaio R, et al.
Characterization of CD44+ALDH1+Ki-67- Cells in Non-malignant and Neoplastic Lesions of the Breast.
Anticancer Res. 2016; 36(9):4629-38 [PubMed] Related Publications
BACKGROUND: Cancer stem cells are tumor cells that present self-renewal, clonal tumor initiation capacity and clonal long-term repopulation potential. We have previously demonstrated that the co-expression of the breast cancer stem cell (BCSC) markers hyaluronan receptor (CD44) and aldehyde dehydrogenase-1 (ALDH1) in ductal carcinomas in situ could be determinant for disease progression. Combining these established BCSC markers with Ki-67 to evaluate quiescence we sought to identify, evaluate the distribution and estimate the mean percentages of CD44(+)ALDH1(+)Ki-67(-) breast cells.
MATERIALS AND METHODS: Triple-immunohistochemistry for CD44, ALDH1 and Ki-67 was applied in a series of 16 normal, 54 non-malignant and 155 malignant breast tissues. Clinical relevance was inferred by associations with markers of breast cancer behavior, progression and survival.
RESULTS: The mean percentages of cells with this phenotype increased significantly from non-malignant lesions to high-grade ductal carcinomas in situ, decreasing in invasive ductal carcinomas, as also evidenced by an inverse correlation with histological grade and tumor size. The mean percentage of CD44(+)ALDH1(+)Ki-67(-) cells was also significantly higher in women who developed distant metastasis and died due to breast cancer, and a significant association with human epidermal growth factor type 2 (HER2) negativity was observed.
CONCLUSION: Our novel findings indicate that CD44(+)ALDH1(+)Ki-67(-) tumor cells may favor distant metastasis and can predict overall survival in patients with ductal carcinomas of the breast. More importantly, quiescence may have a crucial role for tumor progression, treatment resistance and metastatic ability of BCSCs.

Tang X, Li X, Li Z, et al.
Downregulation of CXCR7 inhibits proliferative capacity and stem cell-like properties in breast cancer stem cells.
Tumour Biol. 2016; 37(10):13425-13433 [PubMed] Related Publications
Breast cancer stem cells (bCSCs) are considered an obstacle in breast cancer therapy because they exhibit long-term proliferative potential, phenotypic plasticity and high resistance to the current therapeutics. CXC chemokine receptor type 7 (CXCR7), which provides a growth advantage to breast cancer cells, has recently been demonstrated to play an important role in the maintenance of stem cell-like properties in the CSCs of glioblastoma and lung cancer, yet its role in bCSCs remains elusive. In this study, CD44(+)/CD24(low) bCSC-enriched cells (bCSCs for short) were isolated from MCF-7 cells, and CXCR7 was stably knocked down in bCSCs via lentivirus-mediated transduction with CXCR7 short hairpin RNA (shRNA). Knockdown of CXCR7 in bCSCs decreased the proportion of CD44(+)/CD24(low) cells, and markedly reduced the clonogenicity of the cells. Moreover, silencing of CXCR7 downregulated the expression of stem cell markers, such as aldehyde dehydrogenase 1 (ALDH1), Oct4, and Nanog. In addition, CXCR7 silencing in bCSCs suppressed cell proliferation and G1/S transition in vitro, and delayed tumor growth in vivo in a xenograft mouse model. In situ immunohistochemical analysis revealed a reduction in Ki-67 expression and enhanced apoptosis in the xenograft tumors as a result of CXCR7 silencing. Furthermore, combined treatment with CXCR7 silencing and epirubicin displayed an outstanding anti-tumor effect compared with either single treatment. Our study demonstrates that CXCR7 plays a critical role in the maintenance of stem cell-like properties and promotion of growth in bCSCs, and suggests that CXCR7 may be a candidate target for bCSCs in breast cancer therapy.

Lin S, Zhou S, Jiang S, et al.
NEK2 regulates stem-like properties and predicts poor prognosis in hepatocellular carcinoma.
Oncol Rep. 2016; 36(2):853-62 [PubMed] Related Publications
NEK2 has been estimated to play an important role in cancer progression. However, its relevance in hepatocellular carcinoma (HCC) has not yet been explored. Immunohistochemistry revealed NEK2 expression was upregulated in HCC. NEK2-positive hepatocellular carcinoma patients were associated with poor prognosis after surgery compared with NEK2-negative patients based on Kaplan-Meier curves. Deletion of NEK2 reduced self-renewal properties and chemotherapeutic resistance, and decreased the stemness associated genes in cell lines. NEK2 was associated with unfavorable outcomes in HCC patients, and was revealed to regulate self-renewal property by means of Wnt/β-catenin signaling, and chemotherapeutic resistance by preferential regulation of the expression of ABCG2 and ALDH1A1 in HCC cells.

Liu Y, Lu R, Gu J, et al.
Aldehyde dehydrogenase 1A1 up-regulates stem cell markers in benzo[a]pyrene-induced malignant transformation of BEAS-2B cells.
Environ Toxicol Pharmacol. 2016; 45:241-50 [PubMed] Related Publications
Recently, Aldehyde dehydrogenase 1A1 (ALDH1A1) has been proposed to be a common marker of cancer stem cells and can be induced by benzo[a]pyrene (B[a]P) exposure. However, the underlying mechanism of how ALDH1A1 contributes to B[a]P-induced carcinogenesis in human bronchial epithelial cells remains unclear. Here, we found that B[a]P up-regulated expression levels of stem cell markers (ABCG2, SOX2, c-Myc and Klf4), epithelial-mesenchymal transition (EMT) associated genes (SNAIL1, ZEB1, TWIST and β-CATENIN) and cancer-related long non-coding RNAs (lncRNAs; HOTAIR and MALAT-1) in malignant B[a]P-transformed human bronchial epithelial cells (BEAS-2B-T cells), and these up-regulations were dependent on increased expression of ALDH1A1. The inhibition of endogenous ALDH1A1 expression down-regulated expression levels of stem cell markers and reversed the malignant phenotype as well as reduced the chemoresistance of BEAS-2B-T cells. In contrast, the overexpression of ALDH1A1 in BEAS-2B cells increased the expression of stem cell markers, facilitated cell transformation, promoted migratory ability and enhanced the drug resistance of BEAS-2B cells. Overall, our data indicates that ALDH1A1 promotes a stemness phenotype and plays a critical role in the BEAS-2B cell malignant transformation induced by B[a]P.

Cao X, Ren K, Song Z, et al.
7-Difluoromethoxyl-5,4'-di-n-octyl genistein inhibits the stem-like characteristics of gastric cancer stem-like cells and reverses the phenotype of epithelial-mesenchymal transition in gastric cancer cells.
Oncol Rep. 2016; 36(2):1157-65 [PubMed] Related Publications
7-Difluoromethoxyl-5,4'-di-n-octyl genistein (DFOG), a novel synthetic genistein analogue, exerts anticarcinogenic activity in several types of cancers, including gastric cancer. Accumulating evidence in recent years strongly indicates the existence of cancer stem cells in gastric cancer. The objective of the present study was to investigate whether DFOG inhibits the stemness and reverses the epithelial-mesenchymal transition (EMT) phenotype of gastric cancer stem-like cells (GCSLCs) derived from human gastric cancer SGC-7901 cells and to identify its potential mechanism. Sphere-forming cells (SFCs) from the SGC-7901 cells possessed the properties of GCSLCs. DFOG preferentially inhibited self-renewal, cell migration and cell invasion, and downregulated the expression of stem cell biomarkers in a dose-dependent manner. At the molecular level, these effects were accompanied by the downregulation of forkhead box M1 (FoxM1). Meanwhile, FoxM1 siRNA transfection was able to synergize the inhibition of expression of FoxM1 and Twist1 induced by DFOG in GCSLCs. In addition, we found that DFOG treatment decreased the expression of N-cadherin and increased the expression of E-cadherin. More importantly, FoxM1 siRNA transfection cooperated with DFOG to suppress the self-renewal capacity, cell migration and cell invasion, and downregulated the expression of CD133, CD44, ALDH1, and also regulated the expression of N-cadherin and E-cadherin. These findings showed that DFOG inhibited the stem-like characteristics of GCSLCs and reversed the EMT phenotype by modulation of FoxM1 and further decreased Twist1 expression. Our results provide a further rationale and experimental basis for using DFOG to improve the efficacy of treatment for patients with gastric cancer.

Oue N, Mukai S, Imai T, et al.
Induction of KIFC1 expression in gastric cancer spheroids.
Oncol Rep. 2016; 36(1):349-55 [PubMed] Related Publications
Gastric cancer (GC) is one of the most common human cancers. Spheroid colony formation is an effective model for characterization of cancer stem cells. However, gene expression profiles of spheroid colonies obtained from GC cells have not been examined. We performed microarray analyses by Human Genome U133 Plus 2.0 Array in spheroid body-forming and parental cells from MKN-45 and MKN-74 GC cell lines. Kinesin family member C1 (KIFC1) was expressed >2-fold higher in spheroid body-forming cells than in parental cells in both GC lines. Both the number and size of spheres from MKN-45 cells were significantly reduced upon KIFC1 siRNA-transfection compared with negative control siRNA-transfection. Immunohistochemical analysis of 114 GC tissue samples revealed that 42 (37%) of GC cases were positive for KIFC1 expression. GC cases positive for KIFC1 were found more frequently in stage III/IV cases than in stage I/II cases. GC cases positive for KIFC1 were found more frequently in intestinal type GC cases than in diffuse type GC cases. Furthermore, KIFC1-positive GC cases showed high Ki-67 labeling index. Kaplan-Meier analysis demonstrated that KIFC1 expression was not associated with survival. We found positive expression of KIFC1 in CD44‑positive GC and aldehyde dehydrogenase 1 (ALDH1)-positive GC cells. Our results showed that KIFC1 is overexpressed in GC. Since knockdown of KIFC1 inhibited sphere formation, KIFC1 likely plays an important role in cancer stem cells.

Kim SH, Kaschula CH, Priedigkeit N, et al.
Forkhead Box Q1 Is a Novel Target of Breast Cancer Stem Cell Inhibition by Diallyl Trisulfide.
J Biol Chem. 2016; 291(26):13495-508 [PubMed] Article available free on PMC after 24/06/2017 Related Publications
Diallyl trisulfide (DATS), a metabolic byproduct of garlic, is known to inhibit the growth of breast cancer cells in vitro and in vivo This study demonstrates that DATS targets breast cancer stem cells (bCSC). Exposure of MCF-7 and SUM159 human breast cancer cells to pharmacological concentrations of DATS (2.5 and 5 μm) resulted in dose-dependent inhibition of bCSC, as evidenced by a mammosphere assay and flow cytometric analysis of aldehyde dehydrogenase 1 (ALDH1) activity and the CD44(high)/CD24(low)/epithelial specific antigen-positive fraction. DATS-mediated inhibition of bCSC was associated with a decrease in the protein level of FoxQ1. Overexpression of FoxQ1 in MCF-7 and SUM159 cells increased ALDH1 activity and the CD49f(+)/CD24(-) fraction. Inhibition of ALDH1 activity and/or mammosphere formation upon DATS treatment was significantly attenuated by overexpression of FoxQ1. In agreement with these results, stable knockdown of FoxQ1 using small hairpin RNA augmented bCSC inhibition by DATS. Expression profiling for cancer stem cell-related genes suggested that FoxQ1 may negatively regulate the expression of Dachshund homolog 1 (DACH1), whose expression is lost in invasive breast cancer. Chromatin immunoprecipitation confirmed recruitment of FoxQ1 at the DACH1 promoter. Moreover, inducible expression of DACH1 augmented DATS-mediated inhibition of bCSC. Expression of FoxQ1 protein was significantly higher in triple-negative breast cancer cases compared with normal mammary tissues. Moreover, an inverse association was observed between FoxQ1 and DACH1 gene expression in breast cancer cell lines and tumors. DATS administration inhibited ALDH1 activity in vivo in SUM159 xenografts. These results indicate that FoxQ1 is a novel target of bCSC inhibition by DATS.

Pode-Shakked N, Pleniceanu O, Gershon R, et al.
Dissecting Stages of Human Kidney Development and Tumorigenesis with Surface Markers Affords Simple Prospective Purification of Nephron Stem Cells.
Sci Rep. 2016; 6:23562 [PubMed] Article available free on PMC after 24/06/2017 Related Publications
When assembling a nephron during development a multipotent stem cell pool becomes restricted as differentiation ensues. A faulty differentiation arrest in this process leads to transformation and initiation of a Wilms' tumor. Mapping these transitions with respective surface markers affords accessibility to specific cell subpopulations. NCAM1 and CD133 have been previously suggested to mark human renal progenitor populations. Herein, using cell sorting, RNA sequencing, in vitro studies with serum-free media and in vivo xenotransplantation we demonstrate a sequential map that links human kidney development and tumorigenesis; In nephrogenesis, NCAM1(+)CD133(-) marks SIX2(+) multipotent renal stem cells transiting to NCAM1(+)CD133(+) differentiating segment-specific SIX2(-) epithelial progenitors and NCAM1(-)CD133(+) differentiated nephron cells. In tumorigenesis, NCAM1(+)CD133(-) marks SIX2(+) blastema that includes the ALDH1(+) WT cancer stem/initiating cells, while NCAM1(+)CD133(+) and NCAM1(-)CD133(+) specifying early and late epithelial differentiation, are severely restricted in tumor initiation capacity and tumor self-renewal. Thus, negative selection for CD133 is required for defining NCAM1(+) nephron stem cells in normal and malignant nephrogenesis.

Bourguignon LY, Wong G, Shiina M
Up-regulation of Histone Methyltransferase, DOT1L, by Matrix Hyaluronan Promotes MicroRNA-10 Expression Leading to Tumor Cell Invasion and Chemoresistance in Cancer Stem Cells from Head and Neck Squamous Cell Carcinoma.
J Biol Chem. 2016; 291(20):10571-85 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
Human head and neck squamous cell carcinoma is a solid tumor malignancy associated with major morbidity and mortality. In this study, we determined that human head and neck squamous cell carcinoma-derived HSC-3 cells contain a subpopulation of cancer stem cells (CSCs) characterized by a high level of CD44v3 and aldehyde dehydrogenase-1 (ALDH1) expression. Importantly, matrix hyaluronan (HA) induces the up-regulation of stem cell markers that display the hallmark CSC properties. Histone methyltransferase, DOT1L, is also up-regulated by HA in CSCs (isolated from HSC-3 cells). Further analyses indicate that the stimulation of microRNA-10b (miR-10b) expression is DOT1L-specific and HA/CD44-dependent in CSCs. This process subsequently results in the overexpression of RhoGTPases and survival proteins leading to tumor cell invasion and cisplatin resistance. Treatment of CSCs with DOT1L-specific small interfering RNAs (siRNAs) effectively blocks HA/CD44-mediated expression of DOT1L, miR-10b production, and RhoGTPase/survival protein up-regulation as well as reduces tumor cell invasion and enhances chemosensitivity. CSCs were also transfected with a specific anti-miR-10b inhibitor to silence miR-10b expression and block its target functions. Our results demonstrate that the anti-miR-10 inhibitor not only decreases RhoGTPase/survival protein expression and tumor cell invasion, but also increases chemosensitivity in HA-treated CSCs. Taken together, these findings strongly support the contention that histone methyltransferase, DOT1L-associated epigenetic changes induced by HA play pivotal roles in miR-10 production leading to up-regulation of RhoGTPase and survival proteins. All of these events are critically important for the acquisition of cancer stem cell properties, including self-renewal, tumor cell invasion, and chemotherapy resistance in HA/CD44-activated head and neck cancer.

Stanford EA, Wang Z, Novikov O, et al.
The role of the aryl hydrocarbon receptor in the development of cells with the molecular and functional characteristics of cancer stem-like cells.
BMC Biol. 2016; 14:20 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
BACKGROUND: Self-renewing, chemoresistant breast cancer stem cells are believed to contribute significantly to cancer invasion, migration and patient relapse. Therefore, the identification of signaling pathways that regulate the acquisition of stem-like qualities is an important step towards understanding why patients relapse and towards development of novel therapeutics that specifically target cancer stem cell vulnerabilities. Recent studies identified a role for the aryl hydrocarbon receptor (AHR), an environmental carcinogen receptor implicated in cancer initiation, in normal tissue-specific stem cell self-renewal. These studies inspired the hypothesis that the AHR plays a role in the acquisition of cancer stem cell-like qualities.
RESULTS: To test this hypothesis, AHR activity in Hs578T triple negative and SUM149 inflammatory breast cancer cells were modulated with AHR ligands, shRNA or AHR-specific inhibitors, and phenotypic, genomic and functional stem cell-associated characteristics were evaluated. The data demonstrate that (1) ALDH(high) cells express elevated levels of Ahr and Cyp1b1 and Cyp1a1, AHR-driven genes, (2) AHR knockdown reduces ALDH activity by 80%, (3) AHR hyper-activation with several ligands, including environmental ligands, significantly increases ALDH1 activity, expression of stem cell- and invasion/migration-associated genes, and accelerates cell migration, (4) a significant correlation between Ahr or Cyp1b1 expression (as a surrogate marker for AHR activity) and expression of stem cell- and invasion/migration-associated gene sets is seen with genomic data obtained from 79 human breast cancer cell lines and over 1,850 primary human breast cancers, (5) the AHR interacts directly with Sox2, a master regulator of self-renewal; AHR ligands increase this interaction and nuclear SOX2 translocation, (6) AHR knockdown inhibits tumorsphere formation in low adherence conditions, (7) AHR inhibition blocks the rapid migration of ALDH(high) cells and reduces ALDH(high) cell chemoresistance, (8) ALDH(high) cells are highly efficient at initiating tumors in orthotopic xenografts, and (9) AHR knockdown inhibits tumor initiation and reduces tumor Aldh1a1, Sox2, and Cyp1b1 expression in vivo.
CONCLUSIONS: These data suggest that the AHR plays an important role in development of cells with cancer stem cell-like qualities and that environmental AHR ligands may exacerbate breast cancer by enhancing expression of these properties.

Kida K, Ishikawa T, Yamada A, et al.
Effect of ALDH1 on prognosis and chemoresistance by breast cancer subtype.
Breast Cancer Res Treat. 2016; 156(2):261-9 [PubMed] Related Publications
Aldehyde dehydrogenase 1 (ALDH1) has been identified as a breast cancer stem cell marker, but its value as a predictor of prognosis and chemoresistance is controversial. This study investigated the effect of ALDH1 on prognosis and chemoresponse by breast cancer subtype. We immunohistochemically analyzed 653 invasive breast cancer specimens and evaluated correlations among clinicopathological factors, survival status, response to neoadjuvant chemotherapy, and ALDH1 expression. Of 653 specimens, 139 (21.3 %) expressed ALDH1 in tumor cells. ALDH1 expression was correlated significantly with larger tumor size, node metastasis, higher nuclear grade, and with HER2(+) and progesterone/estrogen receptor (HR)(-) subtypes. ALDH1 expression was significantly observed in HER2 type and triple-negative breast cancer (TNBC). Patients with ALDH1(+) cancers had significantly shorter disease-free survival (P < 0001) and overall survival (P = 0.044). ALDH1 expression significantly affected prognosis of luminal types, but not TNBC and HER2-enriched types. For the 234 patients treated with neoadjuvant chemotherapy, pathological complete response (pCR) rate was significantly lower in ALDH1(+) cases (13.5 vs. 30.3 %, P = 0.003). pCR and ALDH1 expression were significantly correlated in TNBC patients (P = 0.003). ALDH1(+) breast cancers tended to be aggressive, with poor prognoses. Although ALDH1(+) TNBC showed higher chemoresistance, ALDH1 had significant impact on prognosis in the luminal type but not in TNBC.

Yan Z, Xu L, Zhang J, et al.
Aldehyde dehydrogenase 1A1 stabilizes transcription factor Gli2 and enhances the activity of Hedgehog signaling in hepatocellular cancer.
Biochem Biophys Res Commun. 2016; 471(4):466-73 [PubMed] Related Publications
The Gli transcription factors are primary transcriptional regulators that mediate the activation of Hedgehog (Hh) signaling. Recent studies have revealed that Gli proteins are also regulated transcriptionally and post-translationally through noncanonical mechanisms, independent of Hh signaling. However, the precise mechanisms involved in the regulation of Gli proteins remain unclear. Using a differential mass-spectrometry approach, we found that aldehyde dehydrogenase 1A1 (ALDH1A1) is associated with transcription factor Gli2. Overexpression of ALDH1A1 increased Gli2 protein levels; in contrast, ALDH1A1 depletion facilitated Gli2 degradation. In addition, Gli2 mRNA expression was not affected by ectopic expression of ALDH1A1, indicating the role of ALDH1A1 in the stabilization of Gli2. Further investigation showed that ALDH1A1 prolonged the stability of Gli2 protein in a catalytic-independent manner. Finally, we showed that overexpression of ALDH1A1 activated the Hh signaling pathway and promoted cell growth, migration and invasion in hepatocellular cancer cells. Together, these results illustrate regulatory roles of ALDH1A1 in the activation of the Hh signaling pathway and highlight a novel mechanism for the aberrant activation of the Hh signaling pathway in hepatocellular cancer cells.

Seo EJ, Kwon YW, Jang IH, et al.
Autotaxin Regulates Maintenance of Ovarian Cancer Stem Cells through Lysophosphatidic Acid-Mediated Autocrine Mechanism.
Stem Cells. 2016; 34(3):551-64 [PubMed] Related Publications
Ovarian cancer shows high mortality due to development of resistance to chemotherapy and relapse. Cancer stem cells (CSCs) have been suggested to be a major contributor in developing drug resistance and relapse in ovarian cancer. In this study, we isolated CSCs through sphere culture of A2780, SKOV3, OVCAR3 epithelial ovarian cancer cells and primary ovarian cancer cells from patients. We identified heat-stable factors secreted from ovarian CSCs stimulated migration and proliferation of CSCs. Mass spectrometry and ELISA analysis revealed that lysophosphatidic acid (LPA) was significantly elevated in CSC culture media compared with non-CSC culture media. Treatment of CSCs with LPA resulted in augmented CSC characteristics such as sphere-forming ability, resistance to anticancer drugs, tumorigenic potential in xenograft transplantation, and high expression of CSC-associated genes, including OCT4, SOX2, and aldehyde dehydrogenase 1. Treatment of CSCs with LPA receptor 1-specific inhibitors or silencing of LPA receptor 1 expression abrogated the LPA-stimulated CSC properties. Autotaxin, an LPA-producing enzyme, is highly secreted from ovarian CSCs, and pharmacological inhibition or knockdown of autotaxin markedly attenuated the LPA-producing, tumorigenic, and drug resistance potentials of CSCs. Clinicopathological analysis showed a significant survival disadvantage of patients with positive staining of autotaxin. In addition, we further identified that AKT1 activity was upregulated in ovarian CSCs through an LPA-dependent mechanism and silencing of AKT1 expression led to suppression of CSC characteristics. These results suggest that autotaxin-LPA-LPA receptor 1-AKT1 signaling axis is critical for maintaining CSC characteristics through an autocrine loop and provide a novel therapeutic target for ovarian CSCs.

Chen J, Xia Q, Jiang B, et al.
Prognostic Value of Cancer Stem Cell Marker ALDH1 Expression in Colorectal Cancer: A Systematic Review and Meta-Analysis.
PLoS One. 2015; 10(12):e0145164 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
OBJECTIVE: Many studies have indicated the prognostic and clinicopathological value of aldehyde dehydrogenase 1 (ALDH1) in colorectal cancer (CRC) patients still remains controversial. Thus we performed this study to clarify the relationship between high ALDH1 expression in CRC and its impact on survival and clinicopathological features.
METHODS: Publications for relevant studies in Pubmed, the Cochrane Library, Embase, and China National Knowledge Infrastructure (CNKI) through April 2015 were identified. Only articles describing ALDH1 antigen with immunohistochemistry in CRC were included. The software RevMan 5.1 was used to analyze the outcomes, including 5-year overall survival (OS), disease-free survival (DFS) and clinicopathological features.
RESULTS: 9 studies with 1203 patients satisfying the criteria were included. The overall rate of high ALDH1 expression was 46.5% by immunohistochemical staining. High ALDH1 expression as an independent prognostic factor was significantly associated with the 5-year OS and DFS (OR = 0.42, 95%CI: 0.26-0.68, P = 0.0004; OR = 0.38, 95%CI: 0.24-0.59, P < 0.0001, respectively). High ALDH1 expression was highly correlated with the tumor (T) stage (T3 + T4 vs. T1 + T2; OR = 2.16, 95%CI: 1.09-4.28, P = 0.03), lymph node (N) stage (N1 + N2 vs. N0; OR = 1.8; 95%CI: 1.17-2.79, P = 0.008), and tumor differentiation (G3 vs. G1 + G2; OR = 1.88; 95%CI: 1.07-3.30, P = 0.03). However, high ALDH1 expression was not significantly correlated with the patient age (>60 years old vs. <60 years old; OR = 1.11, 95%CI: 0.63-1.94, P = 0.72).
CONCLUSIONS: High ALDH1 expression indicates a poor prognosis in CRC patients. Moreover, high ALDH1 expression correlates with the T stage, N stage, and tumor differentiation, but not with age.

Lee CR, Lee SH, Rigas NK, et al.
Elevated expression of JMJD6 is associated with oral carcinogenesis and maintains cancer stemness properties.
Carcinogenesis. 2016; 37(2):119-28 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
Cancer stem cells (CSCs) are defined as a small subpopulation of cancer cells within a tumor and responsible for initiation and maintenance of tumor growth. Thus, understanding of molecular regulators of CSCs is of paramount importance for the development of effective cancer therapies. Here, we identified jumonji domain-containing protein 6 (JMJD6) as a novel molecular regulator of oral CSCs. JMJD6 is highly expressed in CSC-enriched populations of human oral squamous cell carcinoma (OSCC) cell lines. Moreover, immunohistochemical staining revealed significantly high level of JMJD6 in OSCC tissues compared to normal human oral epithelia, suggesting that expression of JMJD6 positively correlates with oral carcinogenesis. Subsequent functional analysis showed that knockdown of endogenous JMJD6 in OSCC strongly suppressed self-renewal capacity, a key characteristic of CSCs, and anchorage-independent growth. Conversely, ectopic expression of JMJD6 enhanced CSC characteristics including self-renewal, ALDH1 activity, migration/invasion and drug resistance. Expression of CSC-related genes was also markedly affected by modulating JMJD6 expression. Mechanistically, JMJD6 induces interleukin 4 (IL4) transcription by binding to its promoter region. IL4 rescues self-renewal capacity in JMJD6- knocked down OSCC cells, suggesting the importance of JMJD6-IL4 axis in oral CSCs. Our studies identify JMJD6 as a molecular determinant of CSC phenotype, suggesting that inhibition of JMJD6 may offer an effective therapeutic modality against oral cancer.

Seidensaal K, Nollert A, Feige AH, et al.
Impaired aldehyde dehydrogenase 1 subfamily member 2A-dependent retinoic acid signaling is related with a mesenchymal-like phenotype and an unfavorable prognosis of head and neck squamous cell carcinoma.
Mol Cancer. 2015; 14:204 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
BACKGROUND: An inverse correlation between expression of the aldehyde dehydrogenase 1 subfamily A2 (ALDH1A2) and gene promoter methylation has been identified as a common feature of oropharyngeal squamous cell carcinoma (OPSCC). Moreover, low ALDH1A2 expression was associated with an unfavorable prognosis of OPSCC patients, however the causal link between reduced ALDH1A2 function and treatment failure has not been addressed so far.
METHODS: Serial sections from tissue microarrays of patients with primary OPSCC (n = 101) were stained by immunohistochemistry for key regulators of retinoic acid (RA) signaling, including ALDH1A2. Survival with respect to these regulators was investigated by univariate Kaplan-Meier analysis and multivariate Cox regression proportional hazard models. The impact of ALDH1A2-RAR signaling on tumor-relevant processes was addressed in established tumor cell lines and in an orthotopic mouse xenograft model.
RESULTS: Immunohistochemical analysis showed an improved prognosis of ALDH1A2(high) OPSCC only in the presence of CRABP2, an intracellular RA transporter. Moreover, an ALDH1A2(high)CRABP2(high) staining pattern served as an independent predictor for progression-free (HR: 0.395, p = 0.007) and overall survival (HR: 0.303, p = 0.002), suggesting a critical impact of RA metabolism and signaling on clinical outcome. Functionally, ALDH1A2 expression and activity in tumor cell lines were related to RA levels. While administration of retinoids inhibited clonogenic growth and proliferation, the pharmacological inhibition of ALDH1A2-RAR signaling resulted in loss of cell-cell adhesion and a mesenchymal-like phenotype. Xenograft tumors derived from FaDu cells with stable silencing of ALDH1A2 and primary tumors from OPSCC patients with low ALDH1A2 expression exhibited a mesenchymal-like phenotype characterized by vimentin expression.
CONCLUSIONS: This study has unraveled a critical role of ALDH1A2-RAR signaling in the pathogenesis of head and neck cancer and our data implicate that patients with ALDH1A2(low) tumors might benefit from adjuvant treatment with retinoids.

Wu Z, Han Y, Li Y, et al.
MiR-218-5p inhibits the stem cell properties and invasive ability of the A2B5⁺CD133⁻ subgroup of human glioma stem cells.
Oncol Rep. 2016; 35(2):869-77 [PubMed] Related Publications
MicroRNAs (miRs) act as oncogenes or tumor-suppressor genes, and regulate the proliferation, apoptosis, invasion, differentiation, angiogenesis and behavior of glioma stem cells, which are important in glioma development and recurrence. The present study was performed to investigate the impact of miR-218-5p on stem cell properties and invasive ability of the A2B5+CD133- human glioma stem cell subgroup. qRT-PCR was used to detect miR-218-5p expression in non-cancerous brain and human glioma tissues, human glioma cell lines and human glioma stem cell lines. Lentivirus vectors encoding miR-218-5p and anti-miR-218-5p were constructed and stably transfected into A2B5+CD133- SHG-139s cells. Neurosphere formation Cell Counting Kit-8 (CCK-8) and Transwell assays, immunofluorescence and qRT-PCR analyses were used to explore the role of miR-218-5p in SHG-139s cells. qRT-PCR analysis showed that miR-218-5p expression was lower in human glioma tissues and cells than in non-cancerous brain tissues and normal human astrocyte cells, and lower in A2B5+CD133- (SHG-139s) cells than in CD133+ (SU2 and U87s) cells. The CCK-8 assay demonstrated that the growth curve was significantly inhibited in the miR-218-5p-SHG-139s cells compared to the miR-control, blank and anti-miR‑218-5p groups. The neurosphere formation assay indicated that upregulation of miR‑218-5p expression inhibited SHG-139s neurosphere formation. Immunofluorescence staining and qRT-PCR showed that miR-218-5p reduced stem cell marker (A2B5, nestin, PLAGL2, ALDH1 and Sox2) expression compared with the controls; however, immunofluorescence staining analysis showed that upregulation of miR-218-5p expression led to no difference in CD133 expression. miR‑218-5p reduced SHG-139s cell invasiveness in the Transwell assay and reduced MMP9 expression as detected in qRT-PCR and immunofluorescence analyses. All differences were statistically significant. miR-218-5p expression was lower in human glioma tissues, cells and the A2B5+CD133- human glioma stem cell subgroup. miR-218-5p may be a tumor-suppressor gene in glioma that functions by upregulating miR-218-5p expression, which inhibits the stem cell properties and invasive properties of SHG-139s cells.

Chen Z, Che Q, He X, et al.
Stem cell protein Piwil1 endowed endometrial cancer cells with stem-like properties via inducing epithelial-mesenchymal transition.
BMC Cancer. 2015; 15:811 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
BACKGROUND: Stem cell protein Piwil1 functions as an oncogene in various tumor types. However, the exact function and mechanism of Piwil1 in endometrial cancer remains unclear.
METHODS: The expression of Piwil1 and its relationships with clinicopathological factors were investigated using immunohistochemistry. Up- or down-regulation of Piwil1 were achieved by stable or transient transfection with plasmids or short hairpin RNA (shRNA). Effects of Piwil1 on cancer cells viability, invasion and migration were evaluated by MTT, plate colony formation, transwell assay and nude mouse tumor xenograft assay. The stem-like properties of endometrial cancer cells was detected by spheroid formation assay. Effects of Piwil1 on expression levels of target genes were detected by qRT-PCR, western blotting and Immunofluorescence.
RESULTS: Compared with atypical hyperplasia and normal tissues, Piwil1 was much higher in endometrial carcinoma tissues. We found that Piwil1 expression was significantly correlated with FIGO stage, lymphovascular space involvement, lymph node metastasis and level of myometrial invasion. Overexpression of Piwil1 functioned to maintain stem-like characteristics, including enhancing tumor cell viability, migration, invasion and sphere-forming activity. Conversely, Piwil1 knockdown inhibited cell viability, migration, invasion, sphere-forming activity in vitro and tumor formation in xenograft model in vivo. Furthermore, study of the expression of epithelial and mesenchymal markers showed that Piwil1 was responsible for an EMT-like phenotype associated with an increase in mesenchymal markers and suppression of E-cadherin. Moreover, Piwil1 augmented expression levels of CD44 and ALDH1 expression, two known endometrial CSC markers, as well as other stemness-associated genes.
CONCLUSIONS: Our results suggested that stem cell protein Piwil1 play important roles in regulating EMT and the acquisition of stem-like properties of endometrial cancer cells. Therefore, it indicated that Piwil1 may represent a promising target for developing a novel treatment strategy for endometrial cancer.

Liu Y, Baglia M, Zheng Y, et al.
ALDH1A1 mRNA expression in association with prognosis of triple-negative breast cancer.
Oncotarget. 2015; 6(38):41360-9 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
ALDH1 is a crucial element in the retinoic acid signaling pathway regulating the self-renewal and differentiation of normal stem cells, and may play an important role in cancer progression. However, research on ALDH1 gene expression and breast cancer prognosis has yielded conflicting results. We evaluated the association between tumor tissue ALDH1A1/ALDH1A3 mRNA expression and triple-negative breast cancer (TNBC) prognosis in the Shanghai Breast Cancer Survival Study (SBCSS, N=463), Nashville Breast Health Study (NBHS, N=86), and Southern Community Cohort Study (SCCS, N=47). Gene expression was measured in RNA isolated from breast cancer tissues. In the SBCSS, higher ALDH1A1 mRNA level was associated with improved disease-free (HR=0.87, 95% CI: 0.80-0.95, per log unit change) and overall survival (HR=0.85, 95% CI: 0.78-0.93 per log unit change) independent of age at diagnosis, TNM stage and treatment. We replicated the findings for overall survival in the NBHS and SCCS (HR = 0.27, 95% CI: 0.10-0.73) and for disease-free survival by a meta-analysis of four publicly-available gene expression datasets (HR = 0.86, 95% CI: 0.76-0.97). No significant association was found for ALDH1A3.Our study suggests high expression of ALDH1A1 mRNA in tumor tissues may be an independent predictor of a favorable TNBC outcome.

Adams A, Warner K, Pearson AT, et al.
ALDH/CD44 identifies uniquely tumorigenic cancer stem cells in salivary gland mucoepidermoid carcinomas.
Oncotarget. 2015; 6(29):26633-50 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
A small sub-population of cells characterized by increased tumorigenic potential, ability to self-renew and to differentiate into cells that make up the tumor bulk, has been characterized in some (but not all) tumor types. These unique cells, namedcancer stem cells, are considered drivers of tumor progression in these tumors. The purpose of this work is to understand if cancer stem cells play a functional role in the tumorigenesis of salivary gland mucoepidermoid carcinomas. Here, we investigated the expression of putative cancer stem cell markers (ALDH, CD10, CD24, CD44) in primary human mucoepidermoid carcinomas by immunofluorescence, in vitro salisphere assays, and in vivo tumorigenicity assays in immunodeficient mice. Human mucoepidermoid carcinoma cells (UM-HMC-1, UM-HMC-3A, UM-HMC-3B) sorted for high levels of ALDH activity and CD44 expression (ALDHhighCD44high) consistently formed primary and secondary salispheres in vitro, and showed enhanced tumorigenic potential in vivo (defined as time to tumor palpability, tumor growth after palpability), when compared to ALDHlowCD44low cells. Cells sorted for CD10/CD24, and CD10/CD44 showed varying trends of salisphere formation, but consistently low in vivo tumorigenic potential. And finally, cells sorted for CD44/CD24 showed inconsistent results in salisphere formation and tumorigenic potential assays when different cell lines were evaluated. Collectively, these data demonstrate that salivary gland mucoepidermoid carcinomas contain a small population of cancer stem cells with enhanced tumorigenic potential and that are characterized by high ALDH activity and CD44 expression. These results suggest that patients with mucoepidermoid carcinoma might benefit from therapies that ablate these highly tumorigenic cells.

Rassouli FB, Matin MM, Saeinasab M
Cancer stem cells in human digestive tract malignancies.
Tumour Biol. 2016; 37(1):7-21 [PubMed] Related Publications
Digestive tract malignancies, including oral, pharyngeal, esophageal, gastric, and colorectal cancers, are among the top 10 most common cancers worldwide. In spite of using various treatment modalities, cancer patients still suffer from recurrence and metastasis of malignant cells. Cancer stem cells (CSCs) are undifferentiated and highly proliferative malignant cells with unique properties mediated by overexpression of stemness markers, metastasis-related proteins, drug transporters, and DNA repair machinery. Due to their salient characteristics, it has been suggested that CSCs are responsible for tumor initiation, progression, invasion, recurrence, and therapy resistance. Exploring different aspects of CSC biology has fueled a great enthusiasm in designing novel therapeutic strategies to help patients. For instance, identification of markers associated with digestive tract CSCs, such as CD44, CD133, CD24, EpCAM, LGR5, ALDH1, and BMI1, has made it possible to develop more accurate diagnosis approaches. In addition, specifically targeting CSCs by their markers imposes fewer side effects and improves therapeutic outcomes. Here, we focus on the current status of CSC biology in digestive tract cancers, with emphasis on CSC markers, and review achieved progress in eradication of digestive tract CSC cells.

Sun M, Zhao H, Xiao Q, et al.
Combined expression of aldehyde dehydrogenase 1A1 and β-catenin is associated with lymph node metastasis and poor survival in breast cancer patients following cyclophosphamide treatment.
Oncol Rep. 2015; 34(6):3163-73 [PubMed] Related Publications
This study investigated the expression of ALDH1A1 and β-catenin in breast cancer patients, and analyzed the correlation of their combined expression with clinicopathological features, chemotherapeutic responses, and prognosis of breast cancer patients. In total 276 human breast cancer tissues and 80 benign hyperplasia tissues were included. The expression of ALDH1A1 and β-catenin was examined using tissue microarray-based immunohistochemistry. ROC curve analysis was performed to determine an optimal cut-off score for the expression of ALDH1A1 and β-catenin, based on the survival status of breast cancer patients. Survival probabilities were estimated by the Kaplan-Meier method. ALDH1A1 expression was higher, but β-catenin showed no significant difference in breast cancer samples compared to controls. Compared with the membrane expression of β-catenin [β-catenin(m)], the cytoplasmic expression of β-catenin [β-catenin(c)] occurred significantly more frequently in breast cancer with the high expression of ALDH1A1 [ALDH1A1(high)] than in breast cancer with the low expression of ALDH1A1 [ALDH1A1(low)] (P=0.014). The expression level of ALDH1A was significantly higher in β-catenin(c) breast cancer than in β-catenin(m) breast cancer (P=0.020). ALDH1A1(high) expression or β-catenin(c) expression alone was associated with lymph node metastasis, and worse clinical outcome in breast cancer patients, especially in patients receiving cyclophosphamide treatment. Combined expression of ALDH1A1(high) and β-catenin(c) was associated with lymph node metastasis, poor outcome, and resistance to cyclophosphamide treatment. β-catenin may regulate ALDH1A1 expression in a subtype of breast cancer with ALDH1A1(high) and β-catenin(c) expression. ALDH1A1(high) and β-catenin

Erfani E, Roudi R, Rakhshan A, et al.
Comparative expression analysis of putative cancer stem cell markers CD44 and ALDH1A1 in various skin cancer subtypes.
Int J Biol Markers. 2016; 31(1):e53-61 [PubMed] Related Publications
INTRODUCTION: Skin cancers, particularly melanoma, are initiated and maintained by a subpopulation of tumor cells expressing stemness markers that are called cancer stem cells (CSCs). This study aimed to evaluate the expression levels and clinicopathological significance of the putative CSC markers CD44 and ALDH1A1 in patients with skin cancer.
METHODS: The expression levels of CD44 and ALDH1A1 were investigated in 107 skin cancer specimens including 58 (54%) basal cell carcinomas (BCC), 37 (35%) squamous cell carcinomas (SCC), and 12 (11%) melanomas using the tissue microarray (TMA) technique. The correlation of the expression levels of these markers and clinicopathological parameters was then analyzed.
RESULTS: The expression levels of CD44 and ALDH1A1 were significantly higher in melanoma patients than patients with SCC or BCC (p<0.001 and p = 0.002, respectively). A higher level of CD44 expression was more often found in melanoma tumor cells with a higher rate of recurrence (p = 0.029) and in SCC cases with ulceration (p = 0.01), while there was no significant correlation between ALDH1A1 expression and other clinicopathological parameters. Similarly, coexpression of CD44 and ALDH1A1 (CD44high/ALDH1A1high) was significantly observed in melanoma samples (p<0.001).
CONCLUSIONS: These findings suggest that a CD44high/ALDH1A1high phenotype in melanoma and a CD44high phenotype in SCC can be considered candidates for targeted therapy of skin cancers aiming at CSCs.

Simões BM, O'Brien CS, Eyre R, et al.
Anti-estrogen Resistance in Human Breast Tumors Is Driven by JAG1-NOTCH4-Dependent Cancer Stem Cell Activity.
Cell Rep. 2015; 12(12):1968-77 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
Breast cancers (BCs) typically express estrogen receptors (ERs) but frequently exhibit de novo or acquired resistance to hormonal therapies. Here, we show that short-term treatment with the anti-estrogens tamoxifen or fulvestrant decrease cell proliferation but increase BC stem cell (BCSC) activity through JAG1-NOTCH4 receptor activation both in patient-derived samples and xenograft (PDX) tumors. In support of this mechanism, we demonstrate that high ALDH1 predicts resistance in women treated with tamoxifen and that a NOTCH4/HES/HEY gene signature predicts for a poor response/prognosis in 2 ER+ patient cohorts. Targeting of NOTCH4 reverses the increase in Notch and BCSC activity induced by anti-estrogens. Importantly, in PDX tumors with acquired tamoxifen resistance, NOTCH4 inhibition reduced BCSC activity. Thus, we establish that BCSC and NOTCH4 activities predict both de novo and acquired tamoxifen resistance and that combining endocrine therapy with targeting JAG1-NOTCH4 overcomes resistance in human breast cancers.

You Q, Guo H, Xu D
Distinct prognostic values and potential drug targets of ALDH1 isoenzymes in non-small-cell lung cancer.
Drug Des Devel Ther. 2015; 9:5087-97 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
Increased aldehyde dehydrogenase 1 (ALDH1) activity has been found in the stem cell populations of leukemia and some solid tumors including non-small-cell lung cancer (NSCLC). However, which ALDH1's isoenzymes are contributing to ALDH1 activity remains elusive. In addition, the prognostic value of individual ALDH1 isoenzyme is not clear. In the current study, we investigated the prognostic value of ALDH1 isoenzymes in NSCLC patients through the Kaplan-Meier plotter database, which contains updated gene expression data and survival information from a total of 1,926 NSCLC patients. High expression of ALDH1A1 mRNA was found to be correlated to a better overall survival (OS) in all NSCLC patients followed for 20 years (hazard ratio [HR] 0.88 [0.77-0.99], P=0.039). In addition, high expression of ALDH1A1 mRNA was also found to be correlated to better OS in adenocarcinoma (Ade) patients (HR 0.71 [0.57-0.9], P=0.0044) but not in squamous cell carcinoma (SCC) patients (HR 0.92 [0.72-1.16], P=0.48). High expression of ALDH1A2 and ALDH1B1 mRNA was found to be correlated to worser OS in all NSCLC patients, as well as in Ade, but not in SCC patients. High expression of both ALDH1A3 and ALDH1L1 mRNA was not found to be correlated to OS in all NSCLC patients. These results strongly support that ALDH1A1 mRNA in NSCLC is associated with better prognosis. In addition, our current study also supports that ALDH1A2 and ALDH1B1 might be major contributors to the ALDH1 activity in NSCLC, since high expression of ALDH1A2 and ALDH1B1 mRNA was found to be significantly correlated to worser OS in all NSCLC patients. Based on our study, ALDH1A2 and ALDH1B1 might be excellent potential drug targets for NSCLC patients.

Yata K, Beder LB, Tamagawa S, et al.
MicroRNA expression profiles of cancer stem cells in head and neck squamous cell carcinoma.
Int J Oncol. 2015; 47(4):1249-56 [PubMed] Article available free on PMC after 13/05/2017 Related Publications
Increasing evidence indicates that cancer stem cells have essential roles in tumor initiation, progression, metastasis and resistance to chemo-radiation. Recent research has pointed out biological importance of microRNAs in cancer stem cell dysregulation. Total number of mature microRNAs in human genome increased to more than 2,500 with the recent up-date of the database. However, currently no information is available regarding microRNA expression profiles of cancer stem cells in head and neck squamous cell carcinoma (HNSCC). Increased ALDH1 activity has been demonstrated as a reliable marker for isolation of cancer stem cells. Therefore, we evaluated the microRNA expression profile of ALDH1-high subpopulations in the HNSCC cell lines UTSCC-9 and UTSCC-90. Initially, we examined cancer stem cell properties of ALDH1-high subpopulations in both cell lines. We analyzed expression of stemness markers, sphere formation capacity and xenograft transplantation into NOD/SCID mice. Our findings validated that ALDH1-high subpopulations showed significantly increased tumor-initiating ability. Furthermore, we investigated the microRNA expression profile of HNSCC stem cells using microRNA array and confirmed the results by quantitative real-time PCR. We found that expressions of miR‑424, let-7a, miR‑6836, miR‑6873 and miR‑7152 were downregulated, whereas miR‑147b was upregulated with statistical significance in the ALDH1-high subpopulation. In conclusion, we identified a subset of microRNAs that were differentially expressed in ALDH1-high subpopulation, providing new microRNA targets to study dysregulation of HNSCC-initiating cells and develop therapeutic strategies aimed at eradicating the tumorigenic stem cells in HNSCC.

Xu X, Chai S, Wang P, et al.
Aldehyde dehydrogenases and cancer stem cells.
Cancer Lett. 2015; 369(1):50-7 [PubMed] Related Publications
Aldehyde dehydrogenases (ALDHs), as essential regulators of aldehyde metabolism in the human body, protect organisms from damage induced by active aldehydes. Given their roles in different cancer types, ALDHs have been evaluated as potential prognostic markers of cancer. ALDHs exhibit high activity in cancer stem cells (CSCs) and may serve as markers of CSCs. Moreover, studies indicated that ALDHs and their regulated retinoic acid, reactive oxygen species and reactive aldehydes metabolism were strongly related with various properties of CSCs. Besides, recent research evidences have demonstrated the transcriptional and post-translational regulation of ALDH expression and activation in CSCs. Thus, this review focuses on the function and regulation of ALDHs in CSCs, particularly ALDH1A1 and ALDH1A3.

Yadav A, Gupta A, Rastogi N, et al.
Association of cancer stem cell markers genetic variants with gallbladder cancer susceptibility, prognosis, and survival.
Tumour Biol. 2016; 37(2):1835-44 [PubMed] Related Publications
Genes important to stem cell progression have been involved in the genetics and clinical outcome of cancers. We investigated germ line variants in cancer stem cell (CSC) genes to predict susceptibility and efficacy of chemoradiotherapy treatment in gallbladder cancer (GBC) patients. In this study, we assessed the effect of SNPs in CSC genes (surface markers CD44, ALCAM, EpCAM, CD133) and (molecular markers NANOG, SOX-2, LIN-28A, ALDH1A1, OCT-4) with GBC susceptibility and prognosis. Total 610 GBC patients and 250 controls were genotyped by using PCR-RFLP, ARMS-PCR, and TaqMan allelic discrimination assays. Chemotoxicity graded 2-4 in 200 patients and tumor response was recorded in 140 patients undergoing neoadjuvant chemotherapy (NACT). Differences in genotype and haplotype frequency distributions were calculated by binary logistic regression. Gene-gene interaction model was analyzed by generalized multifactor dimensionality reduction (GMDR). Overall survival was assessed by Kaplan-Meier survival curve and multivariate Cox-proportional methods. ALCAM Ars1157Crs10511244 (P = 0.0035) haplotype was significantly associated with GBC susceptibility. In GMDR analysis, ALCAM rs1157G>A, EpCAM rs1126497T>C emerged as best significant interaction model with GBC susceptibility and ALDH1A1 rs13959T>G with increased risk of grade 3-4 hematological toxicity. SOX-2 rs11915160A>C, OCT-4 rs3130932T>G, and NANOG rs11055786T>C were found best gene-gene interaction model for predicting response to NACT. In both Cox-proportional and recursive partitioning ALCAM rs1157GA+AA genotype showed higher mortality and hazard ratio. ALCAM gene polymorphisms associated with GBC susceptibility and survival while OCT-4, SOX-2, and NANOG variants showed an interactive role with treatment response.

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