Aldehyde Dehydrogenese-1 High Cancer Stem-like Cells/Cancer-initiating Cells Escape from Cytotoxic T Lymphocytes due to Lower Expression of Human Leukocyte Antigen Class 1

BACKGROUND/AIM

Human gastric cancer stem-like cells (CSCs)/cancer-initiating cells can be identified as aldehyde dehydrogenase-high (ALDHhigh) cells. Cancer immunotherapy employing immune checkpoint blockade has been approved for advanced gastric cancer cases. However, the effectiveness of cancer immunotherapy against gastric CSCs/CICs remains unclear. This study aimed to investigate the susceptibility of gastric CSCs/CICs to immunotherapy.

MATERIALS AND METHODS

Gastric CSCs/CICs were isolated as ALDHhigh cells using the human gastric cancer cell line, MKN-45. ALDHhigh clone cells and ALDHlow clone cells were isolated using the ALDEFLUOR assay. ALDH1A1 expression was assessed via qRT-PCR. Sphere-forming ability was evaluated to confirm the presence of CSCs/CICs. A model neoantigen, AP2S1, was over-expressed in ALDHhigh clone cells and ALDHlow clone cells, and susceptibility to AP2S1-specific TCR-T cells was assessed using IFNγ ELISPOT assay.

RESULTS

Three ALDHhigh clone cells were isolated from MKN-45 cells. ALDHhigh clone cells exhibited a stable phenotype in in vitro culture for more than 2 months. The High-36 clone cells demonstrated the highest sphere-forming ability, whereas the Low-8 cells showed the lowest sphere-forming ability. High-36 cells exhibited lower expression of HLA-A24 compared to Low-8 cells. TCR-T cells specific for AP2S1 showed lower reactivity to High-36 cells compared to Low-8 cells.

CONCLUSION

High-36 cells and Low-8 cells represent novel gastric CSCs/CICs and non-CSCs/CICs, respectively. ALDHhigh CSCs/CICs evade T cells due to lower expression of HLA class 1.

Luminal B Breast Cancer Coexpressing p62 and ALDH1A3 Is Less Susceptible to Radiotherapy

BACKGROUND/AIM

We have reported that p62 (also known as sequestosome 1) is needed for survival/proliferation and tumor formation by aldehyde dehydrogenase 1 (ALDH1) -positive cancer stem cells (CSCs) and that p62high ALDH1A3high expression is associated with a poor prognosis in luminal B breast cancer. However, the association between p62high ALDH1A3high and the benefit from radiotherapy in patients with luminal B breast cancer remains unclear.

MATERIALS AND METHODS

Datasets from the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and The Cancer Genome Atlas (TCGA) were downloaded, and data from p62high ALDH1A3high luminal B patients treated without or with radiotherapy were analyzed by Kaplan-Meier and multivariate Cox regression analyses. We also performed an in vitro tumor sphere formation assay after X-ray irradiation using p62-knockdown ALDH1high luminal B BT-474 cells.

RESULTS

p62high ALDH1A3high patients had poorer clinical outcomes than other luminal B breast cancer patients treated with radiotherapy. The combination of p62 DsiRNA KD and X-ray irradiation suppressed in vitro tumor sphere formation by ALDH1high BT-474 cells. These results suggest that p62 is involved in the reduced effect of X-ray irradiation on ALDH1-positive luminal B breast CSCs.

CONCLUSION

p62 and ALDH1A3 may serve as prognostic biomarkers for luminal B breast cancer patients treated with radiotherapy. Additionally, the combination of p62 inhibition and radiotherapy could be useful for targeted strategies against ALDH1-positive luminal B breast CSCs.

The prognostic value of stem cell markers in triple-negative breast cancer

Among the many consecutive theories of cancer, the stem cell theory is currently the most accepted one. Cancer stem cells are located in small niches with specific environment, renew themselves and are believed to be responsible for many recurrences. They can be highlighted with stem cell markers, but often these markers also label tumor cells, and this may represent a phenotypical change associated with prognosis. In this study, we attempted to match tumor outcomes with the expression of the following stem cell markers: ALDH1, AnnexinA1, CD44, CD117, CD166, Nanog and oct-4. Tissue microarray blocks from triple-negative breast cancers were immunostained for the listed markers, and their expression by the majority of tumor cells (diffuse positivity) was correlated with prognosis. Of the 106 tumors investigated, diffuse positivity was seen in 7 (ALDH1), 33 (AnnexinA1), 53 (CD44), 44 (CD117 membranous only), 49 (CD117), 72 (CD166), 19 (Nanog), and 11 (oct-4) cases. With a median follow-up of 83 months, ALDH1 and CD117 expression was associated with DFS, whereas CD44, CD117 and CD166 were associated with OS estimates, based on Kaplan-Meier analyses. In the multivariate Cox proportional hazard models (including the examined markers and clinicopathological data which had a statistical impact in the univariate analysis), the pN category and the lack of ALDH1 expression were independent prognosticators for DFS, and the pN category and diffuse CD44 staining were independent prognosticators for OS. In the multivariate analysis including all of the examined clinicopathological data and markers, only CD117 showed a statistical impact on OS. We failed to demonstrate a prognostic impact for most stem cell markers tested in triple-negative breast cancer, but lack of ALDH1 staining and CD44 expression appears as of prognostic value, requiring further examination in independent studies.

The Role of Cancer Stem Cell Markers in Ovarian Cancer

Ovarian cancer is the most lethal gynaecological cancer and the eighth most common female cancer. The early diagnosis of ovarian cancer remains a clinical problem despite the significant development of technology. Nearly 70% of patients with ovarian cancer are diagnosed with stages III-IV metastatic disease. Reliable diagnostic and prognostic biomarkers are currently lacking. Ovarian cancer recurrence and resistance to chemotherapy pose vital problems and translate into poor outcomes. Cancer stem cells appear to be responsible for tumour recurrence resulting from chemotherapeutic resistance. These cells are also crucial for tumour initiation due to the ability to self-renew, differentiate, avoid immune destruction, and promote inflammation and angiogenesis. Studies have confirmed an association between CSC occurrence and resistance to chemotherapy, subsequent metastases, and cancer relapses. Therefore, the elimination of CSCs appears important for overcoming drug resistance and improving prognoses. This review focuses on the expression of selected ovarian CSC markers, including CD133, CD44, CD24, CD117, and aldehyde dehydrogenase 1, which show potential prognostic significance. Some markers expressed on the surface of CSCs correlate with clinical features and can be used for the diagnosis and prognosis of ovarian cancer. However, due to the heterogeneity and plasticity of CSCs, the determination of specific CSC phenotypes is difficult.

Enhanced Sensitivity to ALDH1A3-Dependent Ferroptosis in TMZ-Resistant Glioblastoma Cells

Temozolomide (TMZ) is standard treatment for glioblastoma (GBM); nonetheless, resistance and tumor recurrence are still major problems. In addition to its association with recurrent GBM and TMZ resistance, ALDH1A3 has a role in autophagy-dependent ferroptosis activation. In this study, we treated TMZ-resistant LN229 human GBM cells with the ferroptosis inducer RSL3. Remarkably, TMZ-resistant LN229 clones were also resistant to ferroptosis induction, although lipid peroxidation was induced by RSL3. By using Western blotting, we were able to determine that ALDH1A3 was down-regulated in TMZ-resistant LN229 cells. Most intriguingly, the cell viability results showed that only those clones that up-regulated ALDH1A3 after TMZ withdrawal became re-sensitized to ferroptosis induction. The recovery of ALDH1A3 expression appeared to be regulated by EGFR-dependent PI3K pathway activation since Akt was activated only in ALDH1A3 high clones. Blocking the EGFR signaling pathway with the EGFR inhibitor AG1498 decreased the expression of ALDH1A3. These findings shed light on the potential application of RSL3 in the treatment of glioblastoma relapse.

Mechanisms underlying the changes in acetaldehyde dehydrogenase 1 in cholangiocarcinoma

Cholangiocarcinoma (CCA) is the most recurrent malignant tumor found in the biliary system. It originates from the bile duct epithelial cells characterized by easy metastasis, high intermittent rate, and poor prognosis. Acetaldehyde dehydrogenase 1 (ALDH1), a marker of cancer stem cells, the levels of which are particularly elevated in various of malignant tumors. Additionally, the increased ALDH1 levels are closely related to the degree and prognosis of malignant tumors. This study reviewed the mechanisms underlying the changes in ALDH1 levels in CCA.

High expression of PKCλ and ALDH1A3 indicates a poor prognosis, and PKCλ is required for the asymmetric cell division of ALDH1A3-positive cancer stem cells in PDAC

Pancreatic ductal adenocarcinoma (PDAC) is the cancer with the poorest prognosis. One of the major properties reflecting its poor prognosis is high-grade heterogeneity, which leads to insensitivity to anticancer treatments. Cancer stem cells (CSCs) acquire phenotypic heterogeneity, generating abnormally differentiated cells by asymmetric cell division. However, the detailed mechanism leading to phenotypic heterogeneity is largely unknown. Here, we showed that PDAC patients with co-upregulation of PKCλ and ALDH1A3 had the poorest clinical outcome. PKCλ knockdown by DsiRNA in the ALDH1high population of PDAC MIA-PaCa-2 cells attenuated the asymmetric distribution of the ALDH1A3 protein. To monitor asymmetric cell division of ALDH1A3-positive PDAC CSCs, we established stable Panc-1 PDAC clones expressing ALDH1A3-turboGFP (Panc-1-ALDH1A3-turboGFP cells). In addition to MIA-PaCa-2-ALDH1high cells, turboGFPhigh cells sorted from Panc-1-ALDH1A3-turboGFP cells showed asymmetric cell propagation of ALDH1A3 protein. PKCλ DsiRNA in Panc-1-ALDH1A3-turboGFP cells also attenuated the asymmetric distribution of ALDH1A3 protein. These results suggest that PKCλ regulates the asymmetric cell division of ALDH1A3-positive PDAC CSCs. Furthermore, Panc-1-ALDH1A3-turboGFP cells can be useful for the visualization and monitoring of CSC properties such as asymmetric cell division of ALDH1A3-positive PDAC CSCs in time-lapse imaging.

Expression of ALDH1 plays the important role during generation and progression in human cervical cancer

Cervical cancer which is caused by persistent infection with oncogenic human papillomavirus (HPV), is the third most common cancer. HPV infection causes the progression of the normal cervix to cervical intraepithelial neoplasia (CIN) because it often occurs at the function conversion of the cervical squamous epithelium and columnar epithelium zone, further to invasive carcinoma. The difference in the ALDH1 expression was very significant. With the progression of cervical cancer, reports explained obviously increased nuclear and cytoplasm ALDH1 staining in comparisons of cervical carcinomas and normal cervix (P < 0.0001), cervical carcinomas compared with CIN (P = 0.0002). Therefore, ALDH1 as a stem marker, not only resists cervical cancer but also resists in normal cervix and CIN tissues. Developing an experimental method to discover cervical cancer earlier is feasible. Furthermore, the ALDH1 was expressed in human cervical cancer cell lines (Hela, SiHa, CaSki, HT-3, and C33A) together with western blot and immunocytochemical analysis. ALDH1 plays a significant role in nuclear and cytoplasm staining by immunochemistry in single or clustered HT-3 and C33A cells. However, western blot and immunochemical analysis did not detect ALDH1 in HeLa or CaSki, SiHa cells. We also discovered that there were no remarkable differences in age, tumor size, clinical TNM staging, multiple pelvic lymph node metastasis, or histological staging (p > 0.05) between the ALDH1-positive groups in 100 cervical cancer tissues. But after the control variable age, different ALDH rating survival function contrasted, it can be concluded that the higher ALDH1 scores with the survival of patients with the worse condition.

Metabolism in Cancer Stem Cells: Targets for Clinical Treatment

Cancer stem cells (CSCs) have high tumorigenicity, high metastasis and high resistance to treatment. They are the key factors for the growth, metastasis and drug resistance of malignant tumors, and are also the important reason for the occurrence and recurrence of tumors. Metabolic reprogramming refers to the metabolic changes that occur when tumor cells provide sufficient energy and nutrients for themselves. Metabolic reprogramming plays an important role in regulating the growth and activity of cancer cells and cancer stem cells. In addition, the immune cells or stromal cells in the tumor microenvironment (TME) will change due to the metabolic reprogramming of cancer cells. Summarizing the characteristics and molecular mechanisms of metabolic reprogramming of cancer stem cells will provide new ideas for the comprehensive treatment of malignant tumors. In this review, we summarized the changes of the main metabolic pathways in cancer cells and cancer stem cells.

High Expression of p62 and ALDH1A3 Is Associated With Poor Prognosis in Luminal B Breast Cancer

BACKGROUND/AIM

p62 (also known as sequestosome 1) is involved in cancer progression, and high expression of p62 indicates poor clinical outcome in several cancer types. However, the association between p62 gene expression and cancer stem cells (CSCs) in breast cancer subtypes remains unclear.

MATERIALS AND METHODS

In the present study, genomic datasets of primary breast cancer (The Cancer Genome Atlas, n=593; and Molecular Taxonomy of Breast Cancer International Consortium, n=2,509) were downloaded. p62 Expression was then examined in normal and breast cancer tissues derived from the same patients. Kaplan-Meier and multivariate Cox regression analyses were employed to evaluate disease-specific survival. Next, the effect on cell viability and in vitro tumor-sphere formation of p62 knockdown using targeted small interfering RNA was assessed by using cells with high activity of aldehyde dehydrogenase 1 (ALDH1^high).

RESULTS

Patients with normal-like, luminal A or luminal B breast cancer with p62^high had poor prognosis. Furthermore, patients with p62^high ALDH1A3^high luminal B type also exhibited poor prognoses. Knockdown of p62 suppressed viability and tumor-sphere formation by ALDH1^high cells of the luminal B-type cell lines BT-474 and MDA-MB-361. These results suggest that p62 is essential for cancerous progression of ALDH1-positive luminal B breast CSCs, and contributes to poor prognosis of luminal B breast cancer.

CONCLUSION

p62 is potentially a prognostic marker and therapeutic target for ALDH1-positive luminal B breast CSCs.

Transcriptional Expressions of ALDH1A1/B1 as Independent Indicators for the Survival of Thyroid Cancer Patients

Background

Aldehyde dehydrogenase (ALDH) 1 is an important enzyme involved in the regulation of several cellular mechanisms via aldehyde detoxification. High ALDH1 levels were correlated with tumorigenesis and stemness maintenance in cancer.

Methods

We used UALCAN, Human Protein Atlas, Kaplan–Meier plotter, TISIDB, TIMER, and KOBAS databases to investigate the expression and role of ALDH1 in thyroid cancer progression. In addition, quantitative real-time polymerase chain reaction was performed to detect the expression of the target genes in thyroid cancer cell lines and cancer tissues.

Results

Expression of ALDH1A1/B1 was significantly decreased based on individual cancer stages and tumor histology, and high levels of ALDH1A1/B1 were associated with poor overall survival in thyroid cancer patients. Moreover, ALDH1A1/B1 expression was negatively correlated with immune-stimulating genes, major histocompatibility complex, chemokines, and receptors.

Conclusions

These results suggest that ALDH1A1/B1 might serve as potential prognostic biomarkers for thyroid cancer diagnosis.

High aldehyde dehydrogenase 1 activity is related to radiation resistance due to activation of AKT signaling after insulin stimulation in prostate cancer

The association between type 2 diabetes mellitus and prostate cancer is still under investigation, and the relationship between hyperinsulinemia and prostate cancer stem-like cells (CSCs) is elusive. Here, we investigated the function of insulin/AKT signaling in prostate CSCs. We isolated prostate CSCs as aldehyde dehydrogenase 1-high (ALDH1^high) cells from the human prostate cancer 22Rv1 cell line using an ALDEFLUOR assay and established several ALDH1^high and ALDH1^low clones. ALDH1^high clones showed high ALDH1 expression which is a putative CSC marker; however, they showed heterogeneity regarding tumorigenicity and resistance to radiation and chemotherapy. Interestingly, all ALDH1^high clones showed lower phosphorylated AKT (Ser473) (pAKT) levels than the ALDH1^low clones. PI3K/AKT signaling is a key cell survival pathway and we analyzed radiation resistance under AKT signaling activation by insulin. Insulin increased pAKT levels in ALDH1^high and ALDH1^low cells; the fold increase rate of pAKT was higher in ALDH1^high cells than in ALDH1^low cells. Insulin induced resistance to radiation and chemotherapy in ALDH1^high cells, and the increased levels of pAKT induced by insulin were significantly related to radiation resistance. These results suggest that ALDH1 suppresses baseline pAKT levels, but AKT can be activated by insulin, leading to treatment resistance.

Mesothelin Expression Is Not Associated with the Presence of Cancer Stem Cell Markers SOX2 and ALDH1 in Ovarian Cancer

Mesothelin (MSLN) overexpression (OE) is a frequent finding in ovarian carcinomas and increases cell survival and tumor aggressiveness. Since cancer stem cells (CSCs) contribute to pathogenesis, chemoresistance and malignant behavior in ovarian cancer (OC), we hypothesized that MSLN expression could be creating a favorable environment that nurtures CSCs. In this study, we analyzed the expression of MSLN and CSC markers SOX2 and ALDH1 by immunohistochemistry (IHC) in different model systems: primary high-grade serous carcinomas (HGSCs) and OC cell lines, including cell lines that were genetically engineered for MSLN expression by either CRISPR-Cas9-mediated knockout (Δ) or lentivirus-mediated OE. Cell lines, wild type and genetically engineered, were evaluated in 2D and 3D culture conditions and xenografted in nude mice. We observed that MSLN was widely expressed in HGSC, and restricted expression was observed in OC cell lines. In contrast, SOX2 and ALDH1 expression was limited in all tissue and cell models. Most importantly, the expression of CSC markers was independent of MSLN expression, and manipulation of MSLN expression did not affect CSC markers. In conclusion, MSLN expression is not involved in driving the CSC phenotype.

The Prognostic Value of Cancer Stem Cell Markers in Cervical Cancer: A Systematic Review and Meta-Analysis

OBJECTIVES

Prognostic biomarkers in cervical cancer are widely investigated, including cancer stem cell (CSC) markers. However, their significance remains uncertain. This study aimed to determine the role of cervical cancer stem cell (CCSC) markers for survival.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis (PROSPERO CRD42021237072) of studies reporting CCSC markers as the prognostic predictor based on PRISMA guidelines. We included English articles investigating associations of CCSCs expression in tissue tumor with overall survival (OS) or disease-free survival (DFS) from PubMed, EBSCO, and The Cochrane Library databases. The quality of studies was analyzed based on Newcastle-Ottawa Quality Assessment Scale.

RESULTS

From 413 publications, after study selection with inclusion and exclusion criteria, 22 studies were included. High expressions of CCSC markers were associated with poor OS and DFS (HR= 1.05, 95% CI: 1.03 - 1.07, P <0.0001; HR= 1.31, 95% CI: 1.09 - 1.17, P <0.00001; respectively). Sub-analysis of individual CCSC markers indicated significant correlations between CD44 (HR= 1.14, 95% CI: 1.07 - 1.22, P 0.0001), SOX2 (HR= 1.58, 95% CI: 1.17 - 2.14, P 0.003), OCT4 (HR= 1.03, 95% CI: 1.01 - 1.06, P 0.008), ALDH1 (HR= 1.36, 95% CI: 1.13 - 1.64, P 0.001), and CD49f (HR= 3.02, 95% CI: 1.37 - 6.64, P 0.006) with worse OS; OCT4 (HR= 1.14, 95% CI 1.06 - 1.22, P 0.0003), SOX2 (HR= 1.11, 95% CI: 1.06 - 1.16, P <0.0001), and ALDH1 (HR= 1.22, 95% CI: 1.10 - 1.35, P 0.0002) with poor DFS. We did not conduct a meta-analysis for MSI-1 and CK17 because only one study investigated those markers.

CONCLUSION

Expressions of OCT4, SOX2, and ALDH1 were associated with poor OS and DFS in cervical cancer tissue. These markers might have potential roles as prognostic biomarkers to predict unfavorable survival.

Synergistic killing effects of PD-L1-CAR T cells and colorectal cancer stem cell-dendritic cell vaccine-sensitized T cells in ALDH1-positive colorectal cancer stem cells

Cancer stem cells (CSCs) are characterized by self-renewal and unlimited proliferation, providing a basis for tumor occurrence, metastasis, and recurrence. Because CSCs are highly resistant to conventional chemotherapy and radiotherapy, various immunotherapies, particularly chimeric antigen receptor T cell (CAR-T) therapy and dendritic cell (DC)-based vaccine therapy, are currently being developed. Accordingly, in this study, we evaluated programmed cell death ligand-1 (PD-L1) expression in colorectal CSCs (CCSCs) and non-CCSCs and designed a combination immunotherapy synchronously utilizing PD-L1-CAR-T cells together with CCSC-DC vaccine-sensitized T cells for the treatment of colorectal cancer. PD-L1-CAR-T cells specifically recognized the PD-L1 molecule on CCSCs by binding to the extracellular domain of programmed cell death-1. The CCSC-DC vaccine was prepared using CCSC lysates. We found that aldehyde dehydrogenase 1 (ALDH1)-positive CCSCs were abundant in samples from patient tumor tissues and cancer cell lines. Moreover, PD-L1 was highly expressed in ALDH1-positive CCSCs compared with that in non-CCSCs. Monotherapy with PD-L1-CAR-T cells or CCSC-DC vaccine only elicited moderate tumor remission both in vitro and in vivo. However, combination therapy markedly killed cancer cells and relieved the tumor burden in mice. Our findings may provide a novel strategy for the clinical treatment of colorectal malignancy.

Aldehyde dehydrogenase 1 (ALDH1) immunostaining in axillary lymph node metastases is an independent prognostic factor in ALDH1-positive breast cancer

Objective

To determine whether aldehyde dehydrogenase 1 (ALDH1) immunostaining in axillary lymph node metastases in patients with breast cancer is associated with poor clinical prognosis.

Methods

This retrospective study reviewed data from the medical records of patients with immunohistochemistry-confirmed invasive ductal carcinoma (IDC) and 1–3 metastatic lymph nodes in the ipsilateral axilla between December 2012 and July 2015. The association between ALDH1 immunostaining in axillary lymph node metastases and clinical parameters and prognosis was analysed using χ²-test, Kaplan–Meier survival analysis, univariate and multivariate Cox regression analyses.

Results

A total of 229 patients with IDC were enrolled in the study. The median follow-up was 61 months (range, 20–89 months). Patients with ALDH1-positive axillary lymph node metastases had significantly shorter relapse-free survival and overall survival compared with those with ALDH1-negative axillary lymph node metastases. ALDH1 immunostaining in axillary lymph node metastases was a significant predictor of poor prognosis in univariate and multivariate analyses.

Conclusion

This large study with long-term follow-up suggests that ALDH1 immunostaining in axillary lymph node metastases is an independent predictor of poor prognosis in patients with breast cancer. The clinical relevance of this finding should be confirmed in further well-designed prospective studies.

Cancer Stem Cells and Somatic Stem Cells as Potential New Drug Targets, Prognosis Markers, and Therapy Efficacy Predictors in Breast Cancer Treatment

New drug targets, markers of disease prognosis, and more efficient treatment options are an unmet clinical need in breast cancer (BC). We have conducted a pilot study including patients with luminal B stage breast cancer IIA–IIIB. The presence and frequency of various populations of cancer stem cells (CSC) and somatic stem cells were assessed in the blood, breast tumor tissue, and normal breast tissue. Our results suggest that patients with BC can be divided into two distinct groups based on the frequency of aldehyde dehydrogenase positive cells (ALDH1⁺ cells) in the blood (ALDH1^hi and ALDH1^low). In the ALDH1^hi cells group, the tumor is dominated by epithelial tumor cells CD44⁺CD24^low, CD326⁺CD44⁺CD24⁻, and CD326⁻CD49f⁺, while in the ALDH1^low cells group, CSCs of mesenchymal origin and epithelial tumor cells (CD227⁺CD44⁺CD24⁻ and CD44⁺CD24⁻CD49f⁺) are predominant. In vitro CSCs of the ALDH1^low cells group expressing CD326 showed high resistance to cytostatics, CD227⁺ CSCs of the ALDH1^hi cells group are sensitive to cytostatics. Epithelial precursors of a healthy mammary gland were revealed in normal breast tissue of patients with BC from both groups. The cells were associated with a positive effect of chemotherapy and remission in BC patients. Thus, dynamic control of their presence in blood and assessment of the sensitivity of CSCs to cytostatics in vitro can improve the effectiveness of chemotherapy in BC.

ALDH1 and SALL4 Expression in Cell Block Samples from Patients with Lung Adenocarcinoma and Malignant Pleural Effusion

Malignant pleural effusion (MPE) can accompany advanced lung adenocarcinoma. Recent studies suggest that MPE could contain a heterogeneous subpopulation of cells with stem-like properties, such as tumorigenicity and self-renewal, indicating that they could be the source of metastasis. Although previous studies analyzed the correlation between cancer stem cell (CSC) marker expression and clinical outcomes using lung cancer tissues, investigations regarding the association of MPE with CSC marker expression are limited. We performed immunohistochemistry to examine the expression of aldehyde dehydrogenase 1 (ALDH1) and Sal-like 4 (SALL4) in 46 cell block samples of MPE from patients with lung adenocarcinoma. ALDH1-positive and SALL4-positive cancer cells in MPE were detected in 30 (65.2%) and 21 samples (45.7%), respectively. Cluster formation was detected in 26 samples (56.5%). The number of clusters was significantly higher in ALDH1-positive/SALL4-negative samples. SALL4 expression was inversely correlated with the cluster ratio (r = −0.356) and positively associated with the Ki-67 index (r = 0.326), suggesting that MPE cells with high SALL4 expression comprised the proliferative subpopulation. In conclusion, we demonstrated that MPE contains an ALDH1-positive/SALL4-negative subpopulation exhibiting cluster formation and a SALL4-positive proliferative subpopulation.

ALDH1 & CD133 in invasive cervical carcinoma & their association with the outcome of chemoradiation therapy

Background & objectives:

Chemoradiation is the standard therapy for locally advanced invasive cervical cancer and response to treatment determines the outcome. Cancer stem cells (CSCs) and epithelial–mesenchymal transition (EMT) play a role in response to treatment and hence the aim of this study was to evaluate if their levels in pre-treatment biopsies by immunohistochemistry (IHC) could predict response to treatment and outcome.

Methods:

The study comprised 60 patients with FIGO Stage IIB/III invasive cervical carcinoma treated by chemoradiation. They were divided into two groups based on their clinical outcome: group 1, 30 patients who had no evidence of disease at 48 month follow up and group 2, 30 patients who had disease relapse within 6-12 months of treatment completion. IHC was performed for CSC markers (ALDH1, CD133, Nanog and Oct-4), EMT markers (E-cadherin and vimentin) and squamocolumnar junction (KRT7) markers and H-scores determined. Intergroup comparison was performed. The expression of these markers was also evaluated in histological sections of cervical pre-cancer (CIN1 and CIN3) in comparison to normal cervix.

Results:

Cervical Intraepithelial Neoplasia grade 3 (CIN3) showed high expression of ALDH1 and KRT7 as compared to normal cervical epithelium. Aldehyde dehydrogenase 1 (ALDH1) and CD133 were overexpressed in 70 and 24 per cent cervical carcinoma cases whereas E-cadherin showed reduced expression in invasive carcinoma as compared to normal controls. ALDH1 overexpression was significantly associated with disease relapse in invasive cervical carcinoma treated by chemoradiation (P<0.01).

Interpretation & conclusions:

Determination of ALDH1 levels in pre-treatment cervical biopsies of invasive cervical carcinoma may be useful for prediction of response to chemoradiation, with high levels predicting for a poor response.

Increased aldehyde dehydrogenase 1 (ALDH1) levels are associated with chemo-responsiveness in breast cancer patients treated with taxane-adriamycin-cyclophosphamide regimen

BACKGROUND

Increased plasma aldehyde dehydrogenase 1 (ALDH1) levels have been proposed to predict cancer chemoresistance. However, studies have reported inconsistent results, depending on the type of cancer cells used.

OBJECTIVE

This study aimed to investigate the correlation between plasma levels of ALDH1 and chemotherapy responses to the taxane-adriamycin-cyclophosphamide (TAC) regimen in breast cancer patients.

METHODS

Thirty breast cancer patients who underwent chemotherapy using the TAC regimen were included in this study. Blood sampling was performed before chemotherapy was initiated and after the first and third cycles of chemotherapy administration. After 3 cycles of chemotherapy, patients were categorized as non-responsive if the tumor size was reduced <30%, if the tumor size remained the same or increased, or if any new tumors were discovered. Patients were defined as responsive after 3 cycles of chemotherapy if the tumor mass disappeared, if the tumor size was reduced by at least 30% of the initial size and if no new tumors were found.

RESULTS

Among the 30 patients, only five were responsive to the TAC regimen. The clinical response to TAC was not correlated with the patient's age, cancer grading, or tumor stage. A change in the ALDH1 levels was observed after the third cycle of TAC administration, with significantly higher ALDH1 levels observed in responsive compared with non-responsive patients (p < 0.05).

CONCLUSION

The results of this study may indicate a role for ALDH1 in chemoresponsiveness, rather than chemoresistance, for the TAC regimen in breast cancer patients. Further research remains necessary to confirm this result.

Celastrol and Triptolide Suppress Stemness in Triple Negative Breast Cancer: Notch as a Therapeutic Target for Stem Cells

Triple negative breast cancer (TNBC) is observed in ~15% of breast cancers and results in poor survival and increased distant metastases. Within the tumor are present a small portion of cancer stem cells that drive tumorigenesis and metastasis. In this study, we aimed to elucidate whether the two natural compounds, celastrol and triptolide, inhibit stemness in TNBC. MDA-MB-231, BT20, and a patient-derived primary cells (PD-TNBC) were used in the study. Mammosphere assay was performed to assess the stemness. Both celastrol and triptolide treatment suppressed mammosphere formation. Furthermore, the compound suppressed expression of cancer stem cell marker proteins DCLK1, ALDH1, and CD133. Notch signaling plays a critical role in stem cells renewal. Both celastrol or triptolide reduced Notch -1 activation and expression of its downstream target proteins HES-1 and HEY-1. However, when NICD 1 was ectopically overexpressed in the cells, it partially rescued proliferation and mammosphere formation of the cells, supporting the role of notch signaling. Together, these data demonstrate that targeting stem cells and the notch signaling pathway may be an effective strategy for curtailing TNBC progression.

Neuregulin-1-β1 and γ-secretase play a critical role in sphere-formation and cell survival of urothelial carcinoma cancer stem-like cells

Previously, we investigated gene expression in a high aldehyde dehydrogenase 1 expression (ALDH1^high) population of urothelial carcinoma (UC) cells as UC cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) and found that NRG1 expression was upregulated in ALDH1^high cells. NRG1 is a trophic factor that contains an epidermal growth factor (EGF)-like domain that signals by stimulating ERBB receptor tyrosine kinases and the cytoplasmic domain. NRG1 has been determined to be involved in frequent gene fusions with other partners in several malignancies and has a role in carcinogenesis through the NRG1 EGF-like domain and its cognitive receptor ERBBs. We thus aimed to elucidate the function of NRG1 in UC CSCs/CICs in this study. Both NRG1α and NRG1-β1 were preferentially expressed in ALDH1^high cells compared with ALDH1^low cells; however, siRNA experiments revealed that NRG1-β1 but not NRG1-α has a role in sphere formation. The EGF-like domain of NRG1 had a role in sphere formation of UC cells to some extent but was not essential. The intracellular domain of NRG1 did not have a role in sphere-formation. Inhibition of γ-secretase suppressed sphere formation. These findings indicate that cleavage of NRG1-β1 by γ-secretase plays an important role in UC CSC/CIC proliferation; however, the downstream targets of NRG1-β1 remain elusive.

High SLC20A1 Expression Is Associated With Poor Prognoses in Claudin-low and Basal-like Breast Cancers

BACKGROUND/AIM

SLC20A1 has been identified as a prognostic marker in ER+ breast cancer. However, the role of SLC20A1 expression in breast cancer subtypes other than the ER+ types remains unclear.

MATERIALS AND METHODS

Genomics datasets were downloaded and analyzed, and the effect of SLC20A1 knockdown using targeted siRNA on cell viability and tumor-sphere formation was assessed.

RESULTS

SLC20A1^high patients with ER+, claudin-low or basal-like breast cancers showed poor prognoses. SLC20A1^high patients treated with radiotherapy had poor clinical outcomes. SLC20A1 knockdown suppressed the viability of MDA-MB 231 (claudin-low), MDA-MB 468 (basal-like) and MCF-7 (ER+) cells, and tumor-sphere formation by ALDH1^high cells. These results suggest that SLC20A1 is involved in cancer progression and contributes to clinical outcomes in patients with ER+, claudin-low and basal-like breast cancers.

CONCLUSION

SLC20A1 is a potential prognostic marker and therapeutic target in ER+, claudin-low and basal-like breast cancers.

The role of ALDH1A1 in contributing to breast tumour aggressiveness: A study conducted in an African population

Aldehyde dehydrogenase 1 member A1 (ALDH1A1) is one of the most well studied breast cancer stem cells. Its expression has been associated with poor clinicopathological features and clinical outcomes in several studies. This paper studies the expression of ALDH1A1 and its combination with CD44⁺/CD24^-/low breast cancer stem cell and their association with clinicopathological parameters and molecular subtypes.

METHOD

Tissue Microarray was constructed from 222 Formalin Fixed Paraffin Embedded (FFPE) breast cancer tissues. The expression of ALDH1A1, CD44 and CD24 were assessed by Immunohistochemistry (IHC). The association of ALDH1A1 and its association with clinicopathological parameters, molecular subtypes, CD44 and CD24 were studied in an African population. The association between CD44⁺/CD24^-/low/ALDH1⁺ and the clinicopathological phenotypes were also studied.

RESULTS

A high ALDH1A1 expression of 90% was recorded in this study. No association was found between ALDH1A1 and clinicopathological parameters. ALDH1A1 was positively associated with CD24 (r = 0.228, OR-4.599 95% CI- 1.751-12.076, p = 0.001) and CD44 (r = 0.228, OR-5.538 95%CI- 1.841-16.662, p = 0.001) but not associated with CD44⁺/CD24^-/low (r = 0.134, OR- 2.720 95%CI- 0.959-7.710, p = 0.052). CD44⁺/CD24^-/ALDH1⁺ however had significant associations with Age (p- 0.020, r = 0.161, OR- 2.771, 95%CI 1.147-6.697), Gender (p = 0.004, OR- 15.333 95%CI 1.339-175.54), Tumour grade (p = 0.005, r = 0.197, OR-3.913 95%CI 1.421-10.776) and clinical prognostic staging (p = 0.014, r = 0.182, OR-3.028 95%CI- 1.217-7.536). There was no association between CD44⁺/CD24^-/ALDH1⁺ and the molecular subtypes.

CONCLUSION

The high expression of ALDH1A1 in breast cancer makes it an important target for targeted therapy. This study further confirms the increased tumourigenicity of CD44⁺/CD24^-/ALDH1⁺ combination phenotype and its association with increased tumour grade and clinical prognostic stage. Survival studies of ALDH1A1 and other breast cancer stem cells in African populations are strongly recommended to help further understand their effect on tumour aggressiveness.

Expression pattern of ALDH1, E-cadherin, Vimentin and Twist in early and late onset sporadic colorectal cancer

Aim: To evaluate the expression pattern of ALDH1 (aldehyde dehydrogenase 1), E-cadherin, Vimentin and Twist in early and late onset sporadic colorectal cancer (CRC) and to study association of their expression with the occurrence of CRC at a young age. Materials & methods: Immunohistochemistry of ALDH1, E-cadherin, Vimentin and Twist was performed on 103 pretreated CRC biopsy samples. Results: ALDH1 expression was found to have strong correlation with early onset CRC (p < 0.0001). Conclusion: High ALDH1 expression correlates with the early onset of CRC. ALDH1 over-expression correlates with poor overall survival in colon cancer.

Clinicopathological Significance of Tumor Stem Cell Markers ALDH1 and CD133 in Colorectal Carcinoma

Background & Objective:

Colorectal cancer (CRC) is the third most common cancer worldwide with a high mortality rate. The main causes of death in patients are recurrence and metastasis which are mainly attributed to the small subpopulation of cells within tumors called cancer stem cells (CSCs). This study aimed to evaluate the correlation between the expression of ALDH1 and CD133 as CSC associated markers and clinicopathological characteristics in CRC.

Methods:

In this cross-sectional study, a total of 483 CRC tumor samples were immunohistochemically stained for detection of CD133 and ALDH1 markers. Correlations of marker expression with clinicopathological factors were also evaluated.

Results:

There was a significant correlation between the luminal intensity of CD133 and neural invasion (P=0.05) and between the cytoplasmic intensity of CD133 and metastasis (P=0.05). In terms of H-score, a positive significant relation was observed between cytoplasmic expression of CD133 and lymph node (P=0.02), neural (P=0.04) and vascular invasion (P=0.02). The ALDH1 cytoplasmic expression showed a significant correlation with tumor size (P=0.001).

Conclusion:

Our findings showed that increased expression of CD133 and ALDH1 is associated with tumor progression and worse outcomes in CRC patients. These markers can be good candidates for localized targeting of CSCs using antibodies. Future researches need to be improved approaches for early detection of CRC, and treatment monitoring for CRC and other cancers.

Wogonoside Attenuates Cutaneous Squamous Cell Carcinoma by Reducing Epithelial-Mesenchymal Transition/Invasion and Cancer Stem-Like Cell Property

Purpose

Cutaneous squamous cell carcinoma (cSCC) is the most common second basal cell carcinoma in our population. Wogonoside, the main in vivo metabolite of wogonin, possesses anti-inflammatory, anti-angiogenesis and anti-cancer activities. Nevertheless, the effectiveness of wogonoside therapy on cSCC has not been clarified.

Methods

In this study, we investigated the effects of wogonoside on cell proliferation, invasion, epithelial–mesenchymal transition (EMT) and cancer stem-like cell (CSC) properties of SCL-1 and SCC12 cell lines, and the effects on tumor formation in vivo. In vitro, cells were treated with 0, 25, 50 and 100 μM wogonoside for 48 h. In vivo, SCL-1 cells were subcutaneously injected into the right thigh of mice to form xenograft tumors. Animals were randomly divided into two groups (n=10): the control group and the 80 mg/kg wogonoside group.

Results

The results showed that wogonoside attenuated proliferation, invasion and EMT of SCL-1 and SCC12 cell lines, and enhanced the rate of apoptosis. Meanwhile, wogonoside efficiently abolished the CSC traits of cSCC; the expression of CSC markers (ALDH1, SOX-2, Oct4 and CD44) and the percentage of CD133⁺ cells were remarkably downregulated. In addition, we found that wogonoside repressed the activation of both PI3K/AKT and Wnt/β-catenin pathways. In vivo, wogonoside significantly inhibited tumor formation.

Conclusion

The results indicated that wogonoside could attenuate cSCC by reducing EMT, invasion and CSC properties. The efficacy of intervention may be related to inhibition of the PI3K/Akt and Wnt/β-catenin pathways. These novel findings could furnish new ideas on the potential therapeutic application of wogonoside in cSCC cancellation and cancer intervention.

Expression of PD-L1, cancer stem cell and epithelial-mesenchymal transition phenotype in non-small cell lung cancer

The purpose of this study was to investigate the expression of PD-L1, cancer stem cells (CSC) markers (CD44, NANOG, and ALDH1) and epithelial-mesenchymal transition (EMT) markers and to evaluate their correlation and prognostic significance in non-small cell lung cancer (NSCLC) patients. PD-L1 protein expression was evaluated in resected 277 NSCLC cases and its correlation with CSC and EMT marker expression and survival was determined based on immunohistochemical (IHC) analysis. mRNA expression obtained from The Cancer Genome Atlas and the Kaplan-Meier plotter database were compared with the IHC results. PD-L1 expression was negatively correlated with ALDH1 expression in adenocarcinoma by IHC and mRNA expression. PD-L1 expression was also associated with mesenchymal phenotype (vimentin and TWIST) adenocarcinoma by IHC and mRNA expression. PD-L1 expression was associated with poor prognosis in adenocarcinoma by IHC. However, NANOG or ALDH1 expression measured by IHC and mRNA expression was correlated with a favourable prognosis in adenocarcinoma. Epithelial marker p120-catenin detected by IHC and mRNA expression was associated with a favourable prognosis in adenocarcinoma, however mesenchymal marker TWIST was associated with a worse prognosis. Patients with low PD-L1 and high ALDH1 expression showed more favourable prognoses than adenocarcinoma patients with other expression patterns. In multivariate analysis, ALDH1 detected by IHC and mRNA expression was an independent favourable prognostic marker for adenocarcinoma. Our study results support the hypothesis that PD-L1 interacts with CSC and EMT features and that PD-L1, ALDH1, and the mesenchymal phenotype may serve as tandem markers as prognostic factor in NSCLC.

HSPA1L Enhances Cancer Stem Cell-Like Properties by Activating IGF1Rβ and Regulating β-Catenin Transcription

Studies have shown that cancer stem cells (CSCs) are involved in resistance and metastasis of cancer; thus, therapies targeting CSCs have been proposed. Here, we report that heat shock 70-kDa protein 1-like (HSPA1L) is partly involved in enhancing epithelial–mesenchymal transition (EMT) and CSC-like properties in non-small cell lung cancer (NSCLC) cells. Aldehyde dehydrogenase 1 (ALDH1) is considered a CSC marker in some lung cancers. Here, we analyzed transcriptional changes in genes between ALDH1high and ALDH1low cells sorted from A549 NSCLC cells and found that HSPA1L was highly expressed in ALDH1high cells. HSPA1L played two important roles in enhancing CSC-like properties. First, HSPA1L interacts directly with IGF1Rβ and integrin αV to form a triple complex that is involved in IGF1Rβ activation. HSPA1L/integrin αV complex-associated IGF1Rβ activation intensified the EMT-associated cancer stemness and γ-radiation resistance through its downstream AKT/NF-κB or AKT/GSK3β/β-catenin activation pathway. Secondly, HSPA1L was also present in the nucleus and could bind directly to the promoter region of β-catenin to function as a transcription activator of β-catenin, an important signaling protein characterizing CSCs by regulating ALDH1 expression. HSPA1L may be a novel potential target for cancer treatment because it both enhances IGF1Rβ activation and regulates γβ-catenin transcription, accumulating CSC-like properties.

The F-box protein FBXO11 restrains hepatocellular carcinoma stemness via promotion of ubiquitin-mediated degradation of Snail

Expression of the F‐box protein FBXO11 has been shown to be down‐regulated in various tumors, but its role in hepatocellular carcinoma (HCC) progression remains unclear. Here, we examined the role of FBXO11 in HCC cell stemness. We report that FBXO11 expression is significantly decreased in HCC cells, and overexpression of FBXO11 decreased the expression of HCC stemness markers, ALDH1 activity and sphere‐forming ability. In addition, overexpression of FBXO11 reduced the migration ability and epithelial‐mesenchymal transition of HCC cells. Mechanistically, overexpression of FBXO11 decreased the protein level, but not mRNA level, of Snail by directly interacting with Snail and promoting Snail degradation through the ubiquitin‐proteasome system. Overexpression of Snail rescued the inhibitory effect of FBXO11 overexpression on HCC cell stemness. This study reveals the existence of a novel FBXO11/Snail regulatory axis that is necessary for HCC cell stemness.

Insulin growth factor-1 pathway in cervical carcinoma cancer stem cells

Cancer stem cells (CSC) drive tumour progression and are implicated in relapse and resistance to conventional cancer therapies. Identification of differentially expressed genes by gene expression (GEP) profiling may help identify the differentially activated signalling pathways in cancer stem cells as opposed to bulk tumour cells which will provide new insights into cancer stem cell biology and aid in identification of novel therapeutic targets. Our study focused on the inhibition of CSC from cervical cancer cell lines by targeting insulin-like growth factor (IGF), which was identified by differential GEP. Targeted inhibition of IGF-1 by JB-1 trifluoroacetate (inhibitor of IGF) was carried out in SiHa, RSBS-14 and RSBS-43 cervical cancer derived cell lines. Effect of cisplatin was also evaluated. Inhibition of IGF-1 signalling was confirmed by demonstration of reduction in p-Akt levels. The cell biological effects of IGF-1 inhibition included an increase in G2M/S fraction, increased apoptosis and decreased invasive ability. JB-1 and cisplatin showed synergism. However, transcript levels of stemness and EMT markers showed variable levels following IGF inhibition. Overall, this proof-of-concept study has shown that IGF-1 is an attractive target for inhibition of CSC in invasive cervical cancer.

The Prognostic Value of Cancer Stem Cell Markers (Notch1, ALDH1, and CD44) in Primary Colorectal Carcinoma

BACKGROUND

Cancer stem cells proved to have a vital role in cell migration, invasion, metastasis, and treatment resistance of colorectal cancer (CRC) that subsequently lead to poor clinical outcomes. These stem cells may be a novel therapeutic target for the management of CRC progression. Signals of the Notch-1 pathway are responsible for acquisition of stem cell characters. ALDH1 and CD44 are usually detected in stem cells in colorectal cancer.

AIM

The aims of this work are to evaluate the immunohistochemical expression of cancer stem cell markers ALDH1, Notch1, and CD44 in colorectal cancer and investigate their correlation with clinicopathological characters and patient survival.

METHODS

Paraffin-embedded specimens of 70 patients with primary colorectal carcinoma were analyzed for Notch 1, ALDH1, and CD44 expressions by immunohistochemistry.

RESULTS

Notch1 was mainly located in the cytoplasm of CRC tissues, rarely expressed in adjacent normal tissues. A highly statistically significant relationship was found between grading, lymphovascular invasion, the degree of lymphocytic infiltration, peritumoral budding, lymph node ratio, lymph node metastasis, and Notch1 expression (p < 0.001). There was a highly statistically significant relationship found between AJCC stage and Notch1 expression (p < 0.001). CD44 was mainly located in the cell membrane of CRC tissues. A highly statistically significant relationship was found between grading (p = 0.006), lymphovascular invasion, the degree of lymphocytic infiltration, peritumoral budding, lymph node metastasis, lymph node ratio, and CD44 expression (p < 0.001). There was a highly statistically significant relationship found between AJCC stage and CD44 expression (p < 0.001). ALDH1 was detected in the cytoplasm of the CRC tissue. A highly statistically significant relationship was found between grading, lymphovascular invasion, the degree of lymphocytic infiltration, peritumoral budding, lymph node metastasis, lymph node ratio, and ALDH1 expression (p < 0.001). There was a highly statistically significant relationship found between AJCC stage and ALDH1 expression (p < 0.001). There is a highly statistically significant direct correlation between Notch1, CD44 expression, and ALDH1 expression (p < 0.001).

CONCLUSIONS

There is a substantial correlation between Notch 1, ALDH1, and CD44 as cancer stem cell markers and lymph node metastasis, advanced stage and tumor recurrence in colorectal carcinoma.

CONCLUSION

Expression of stem cell markers ALDH1, Notch1, and CD44 correlates with poor prognosis in a CRC and represents an independent prognostic factor. They are associated with a feature of epithelial-mesenchymal transition evidenced by their association with high tumor burden.

Functional study of acetaldehyde dehydrogenase 1 (ALDH1) in keratinocytes: microarray integrating bioinformatics approaches

The function of acetaldehyde dehydrogenase 1 (ALDH1) has been gradually elucidated in several diseases, especially in various cancers. However, the role of ALDH1 in skin-related diseases has been mostly unknown. Previously, we found that ALDH1 is involved in the pathogenesis of atopic dermatitis (AD). In this study, we used high-throughput screening (HTS) approaches to identify critical factors associated with ALDH1 in human keratinocytes to reveal its functions in skin. We overexpressed ALDH1 in human HaCaT keratinocytes and then conducted serial HTS studies, a DNA microarray and antibody array integrated with bioinformatics algorithms. Together, those tests identified several novel genes associated with the function of ALDH1 in keratinocytes, as well as AD, including CTSG and CCL11. In particular, GNB3, GHSR, TAS2R9, FFAR1, TAS2R16, CCL21, GPR32, NPFFR1, GPR15, FBXW12, CCL19, EDNRA, FFAR3, and RXFP3 proteins were consistently detected as hub proteins in the PPI maps. By integrating the datasets obtained from these HTS studies and using the strengths of each method, we obtained new insights into the functional role of ALDH1 in skin keratinocytes. The approach used here could contribute to the clinical understanding of ALDH1-associated applications for the treatment of AD.Communicated by Ramaswamy H. Sarma.

Cancer stem cell markers ALDH1 and Bmi1 expression in oral erythroplakia revisited: Implication for driving the process of field cancerization

The correlation of ALDH1 and Bmi1 expression in potentially malignant oral erythroplakia (OE) with oral carcinoma development was reported in our earlier study. Interestingly, a model of field cancerization orchestrated by the cancer stem cells (CSC) was proposed and suggested the identification of CSC-specific markers is useful for prognosis and providing novel targets for prevention and treatment of field cancerization. We revisited the correlation of ALDH1 and Bmi1 expression in OE with the second and multiple carcinomas development. Strikingly, we observed that the expression of ALDH1 and Bmi1 within a single potentially malignant OE lesion significantly correlate with subsequently developing multiple and multifocal carcinomas, which parallels the process of oral field cancerization. Significantly, ALDH1 and Bmi1 are well-defined markers of CSC for head and neck cancer. Consequently, we provided a preliminary evidence for CSC driving the process of field cancerization.

Comprehensive in situ analysis of ALDH1 and SOX2 reveals increased expression of stem cell markers in high-grade serous carcinomas compared to low-grade serous carcinomas and atypical proliferative serous tumors

Recent studies have shown that re-expression of stem cell factors contribute to pathogenesis, therapy resistance, and recurrent disease in ovarian carcinomas. In this study, we compare the expression and co-expression of stem cell markers ALDH1 and SOX2 in different types of serous ovarian tumors. A total of 215 serous ovarian tumors (161 high-grade serous carcinomas (HGSC), 17 low-grade serous carcinomas (LGSC), 37 atypical proliferative serous tumors (APST)), and 10 cases of serous tubal intraepithelial carcinoma (STIC) were analyzed. Double immunostaining experiments addressed the association of cell proliferation (Ki67) with ALDH1 and the potential co-expression of SOX2 and ALDH1. The prognostic effect was analyzed in the cohort of HGSC. Expression of ALDH1and/or SOX2 was detected with increased frequency in HGSC (88.8%), compared with LGSC (70.5%) and APST (36.4%), while ALDH1 alone was significantly more frequently expressed in LGSC. The majority of all tumor types showed expression of ALDH1 and SOX2 in different cells. Only a minority of HGSC (4.6%) and STIC (20%) showed SOX2/ALDH1 co-expression in > 10% of tumor cells. Double staining also revealed that ALDH1 is associated with the non-proliferating Ki67-negative fraction consistent with a stem cell phenotype. Co-expression of ALDH1 and SOX2 or ALDH1 and Ki67 has no effect on survival. Expression of stem cell factors ALDH1 and/or SOX2 shows increased frequency in high-grade serous ovarian carcinomas compared to low-grade carcinomas and borderline tumors, supporting the concept that stem cell markers play different biological roles in low-grade versus high-grade serous neoplasia of the ovary.

The molecular markers of cancer stem cells in head and neck tumors

Head and neck cancer (HNC) is the six most common malignancy worldwide leading to more than 350,000 deaths annually. Despite recent advances in treatment modalities for these patients, there has been only a slight improvement of prognosis. As cancer stem cells (CSCs) have been implicated in tumor cell survival, progression, and response to therapy, the identification of this tumor subpopulation would have important therapeutic and prognostic implications. In this structured appraisal of the literature, Embase, PubMed, and Ovid were searched for publications that investigated CSC markers of HNC in humans. The search was conducted under the PRISMA guidelines with clear inclusion and exclusion criteria for articles published in the last two decades. The review process resulted in the identification of some key CSC-associated molecules such as CD44, ALDH1, CD133, Oct3/4, Nanog, and Sox2, although a single common CSC sorting marker could not be found. These biomarkers were identified in a range of HNCs but the most common one was squamous cell carcinoma (SCC), predominantly oral SCC. Patient cohorts were of variable size (3-195 individuals) and the most common technique used for detection was immunohistochemistry. Some of the molecules were associated with poor prognosis and may be able to inform the choice of appropriate treatment for these patients.

The Effect of P-Glycoprotein (P-gp), Nuclear Factor-Kappa B (Nf-κb), and Aldehyde Dehydrogenase-1 (ALDH-1) Expression on Metastases, Recurrence and Survival in Advanced Breast Cancer Patients

Objective: To investigate the level of three drug resistance proteins; P-glycoprotein 1 (P-gp), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and aldehyde dehydrogenase isoform 1 (ALDH1) expression and their relationship to metastasis, recurrence and survival in advanced breast cancer patients that received neoadjuvant chemotherapy. Methods: This study is a combination of prospective and retrospective cohort study involving one hundred and thirty one cases of advanced stage invasive breast cancer that have received neoadjuvant chemotherapy. Initial biopsy specimens (incisional biopsy or core biopsy) were taken from paraffin blocks. Immunohistochemistry (IHC) was used to detect P-gp, NF-κB, and ALDH1 expression. Prospectively analysed patients were followed for five years and evaluated for recurrence and death. Results: The expression of P-gp has no significant statistical correlation to metastases (p = 0.659), recurrence (p = 0.862) and survival (p = 0.835) in advanced stage breast cancer patients who received neoadjuvant chemotherapy. Similarly, ALDH1 was not correlated to metastases (p=0.120), recurrence (p = 0.186) and survival (p = 0.254) statistically. We found that NF-κB expression showed a significant correlation to metastases (p=0.004), recurrence (p = 0.016) and overall survival (p = 0.041) in advanced stage breast cancer patients after neoadjuvant chemotherapy. Conclusion: NF-κB expression is a potential marker that can be used to assess or to predict increasing risk of metastases, recurrence and survival in advanced stage breast cancer patients who receive neoadjuvant chemotherapy.

Stem Cells Inhibition by Bevacizumab in Combination with Neoadjuvant Chemotherapy for Breast Cancer

Preclinical works have suggested cytotoxic chemotherapies may increase the number of cancer stem cells (CSC) whereas angiogenesis inhibition may decrease CSC proliferation. We developed a proof of concept clinical trial to explore bevacizumab activity on breast CSC. Breast cancer patients requiring preoperative chemotherapy were included in this open-label, randomized, prospective, multicenter phase II trial. All received FEC-docetaxel combination, and patients randomized in the experimental arm received concomitant bevacizumab. The primary endpoint was to describe ALDH1 (Aldehyde dehydrogenase 1) positive tumor cells rate before treatment and after the fourth cycle. Secondary objectives included safety, pathological complete response (pCR) rate, disease-free survival (DFS), relapse-free survival (RFS), and overall survival (OS). Seventy-five patients were included. ALDH1+ cells rate increase was below the predefined 5% threshold in both arms for the 32 patients with two time points available. Grade 3 or 4 adverse events rates were similar in both arms. A non-significant increase in pCR was observed in the bevacizumab arm (42.6% vs. 18.2%, p = 0.06), but survival was not improved (OS: p = 0.89; DFS: p = 0.45; and RFS: p = 0.68). The increase of ALDH1+ tumor cells rate after bevacizumab-based chemotherapy was less than 5%. However, as similar results were observed with chemotherapy alone, bevacizumab impact on breast CSC cells cannot be confirmed.

Expression of Aldehyde Dehydrogenase (ALDH1) and ATP Binding Cassette Transporter G2 (ABCG2) in Iraqi Patients with Colon Cancer and the Relation with Clinicopathological Features

Tumor initiation cells or cancer stem cell markers ABCG2 and ALDH1 play pivotal roles in invasion, metastasis and resistance to cytotoxic agents. In this study, we evaluated the expression levels of ALDH1 and ABCG2 in Iraqi patients with colon cancer and/or benign colon tumors. We also investigated the association between the expression levels of these markers and patient clincopathological features. The expression levels of ALDH1 and ABCG2 in cancer tissues as well as in benign tumor samples were determined by immunohistochemistry using tumor tissues microarray of TNM (Tumor, Node, Metastasis) in 42 patients with colon cancer samples as well as in 18 corresponding benign tumors. Immunohistochemistry showed that ALDH1 and ABCG2 expression levels increased to 80% and 76%, respectively in colon cancer tissues as compared to 33% and 28% in benign tumor tissues. The expression levels of ALDH1 and ABCG2 were associated with tumor stages. No significant association was found between the expressions levels of these markers and tumor size, gender, patients' age, and lymph node involvement. These results indicate that the expression levels of ALDH1 and ABCG2 increased in colon cancer tissues compared to benign tumor tissues in Iraqi patients.

ALDH1 expression correlates with an epithelial-like phenotype and favorable prognosis in lung adenocarcinoma: a study based on immunohistochemistry and mRNA expression data

PURPOSE

Cancer stem cells (CSC) and epithelial-mesenchymal transition (EMT) pathways are crucial for cancer progression. However, synergistic interactions between CSC and EMT are not clear in non-small cell lung cancer (NSCLC). The objective of this study was to investigate CSC markers such as CD44, NANOG, and ALDH1 expression and its correlation with EMT markers in NSCLC patients. Its association with survival was also determined.

METHODS

CD44, NANOG, and ALDH1 protein expression was evaluated in 267 resected NSCLC and its correlation with e-cadherin, β-catenin, p120 catenin, vimentin, SNAIL, and TWIST expressions was determined based on immunohistochemical and mRNA expression data from The Cancer Genome Atlas (TCGA) database. Survival analyses also were performed based on immunohistochemistry and mRNA expression data from Gene Expression Omnibus dataset.

RESULTS

ALDH1 expression in lung adenocarcinoma was positively correlated with the epithelial-like phenotype, low vimentin and low TWIST in immunohistochemical and mRNA expression data. NANOG and ALDH1 expressions measured by immunohistochemical and mRNA expression profiling data of adenocarcinomas were associated with a favorable prognosis. ALDH1 was an independent favorable prognostic marker for overall survival or recurrence-free survival in adenocarcinoma (P = 0.026 and P = 0.033, respectively). The epithelial-like phenotype expressing P120-catenin and beta-catenin was associated with a favorable prognosis; however, the TWIST-expressing mesenchymal-like phenotype was correlated with an unfavorable prognosis.

CONCLUSIONS

NANOG and ALDH1 protein or mRNA expression showed improved prognosis in adenocarcinoma alone. ALDH1 expression correlated with an epithelial-like phenotype.

Nanog Signaling Mediates Radioresistance in ALDH-Positive Breast Cancer Cells

Recently, cancer stem cells (CSCs) have been identified as the major cause of both chemotherapy and radiotherapy resistance. Evidence from experimental studies applying both in vitro and in vivo preclinical models suggests that CSCs survive after conventional therapy protocols. Several mechanisms are proposed to be involved in CSC resistance to radiotherapy. Among them, stimulated DNA double-strand break (DSB) repair capacity in association with aldehyde dehydrogenase (ALDH) activity seems to be the most prominent mechanism. However, thus far, the pathway through which ALDH activity stimulates DSB repair is not known. Therefore, in the present study, we investigated the underlying signaling pathway by which ALDH activity stimulates DSB repair and can lead to radioresistance of breast cancer cell lines in vitro. When compared with ALDH-negative cells, ALDH-positive cells presented significantly enhanced cell survival after radiation exposure. This enhanced cell survival was associated with stimulated Nanog, BMI1 and Notch1 protein expression, as well as stimulated Akt activity. By applying overexpression and knockdown approaches, we clearly demonstrated that Nanog expression is associated with enhanced ALDH activity and cellular radioresistance, as well as stimulated DSB repair. Akt and Notch1 targeting abrogated the Nanog-mediated radioresistance and stimulated ALDH activity. Overall, we demonstrate that Nanog signaling induces tumor cell radioresistance and stimulates ALDH activity, most likely through activation of the Notch1 and Akt pathways.

High expression of aldehyde dehydrogenase 1 and tissue necrosis factor alpha may relate to chronic infection of buffalo mammary gland

Aldehyde dehydrogenase 1 (ALDH1) and hepatocyte nuclear factor 4A (HNF4A) are the putative mammary stem cell markers. Tissue necrosis factor alpha (TNFA) is involved in inflammation-associated carcinogenesis and cell proliferation. In this study, the gene expression profile of ALDH1, HNF4A and TNFA of buffalo mammary tissue using real-time quantitative PCR (RT-qPCR). Analysis of RT-qPCR data revealed that the relative expression (log2 fold change) of ALDH1 and TNFA during mastitis (vs. lactation) was increased (P < .05) by 2.98 and 4.71, respectively. The relative expression (log2 fold change; -7.39) of stem cell marker, HNF4A was decreased (P < .05) during mastitis. Histological analysis of mammary tissue during mastitis showed thickening of stroma and occasionally hyperplasia, predominantly in prepubertal and non-lactating animals. Although, the level of expression of these genes may vary, depending upon the physiological stage of the animals, however expression of ALDH1 and TNFA was high during mastitis. A systematic study on large samples of buffalo mammary tissue with appropriate comparisons needs to be evaluated with these markers for prognosis of buffalo mammary health.

Phenethyl Isothiocyanate Exposure Promotes Oxidative Stress and Suppresses Sp1 Transcription Factor in Cancer Stem Cells

Aldehyde dehydrogenase 1 (ALDH1) is a cytosolic marker of cancer stem cells (CSCs), which are a sub-population within heterogeneous tumor cells. CSCs associate with therapy-resistance, self-renewal, malignancy, tumor-relapse, and reduced patient-survival window. ALDH1-mediated aldehyde scavenging helps CSCs to survive a higher level of oxidative stress than regular cancer cells. Cruciferous vegetable-derived phenethyl isothiocyanate (PEITC) selectively induces reactive oxygen species (ROS), leading to apoptosis of cancer cells, but not healthy cells. However, this pro-oxidant role of PEITC in CSCs is poorly understood and is investigated here. In a HeLa CSCs model (hCSCs), the sphere-culture and tumorsphere assay showed significantly enriched ALDH^hi CSCs from HeLa parental cells (p < 0.05). Aldefluor assay and cell proliferation assay revealed that PEITC treatments resulted in a reduced number of ALDH^hi hCSCs in a concentration-dependent manner (p < 0.05). In the ROS assay, PEITC promoted oxidative stress in hCSCs (p ≤ 0.001). Using immunoblotting and flow cytometry techniques, we reported that PEITC suppressed the cancer-associated transcription factor (Sp1) and a downstream multidrug resistance protein (P-glycoprotein) (both, p < 0.05). Furthermore, PEITC-treatment of hCSCs, prior to xenotransplantation in mice, lowered the in vivo tumor-initiating potential of hCSCs. In summary, PEITC treatment suppressed the proliferation of ALDH1 expressing cancer stem cells as well as key factors that are involved with drug-resistance, while promoting oxidative stress and apoptosis in hCSCs.

Prognostic value of ALDH1 and Nestin in advanced cancer: a systematic meta-analysis with trial sequential analysis

Background

Novel prognostic markers and therapeutic targets for advanced cancer are urgently needed. This report with trial sequential analysis (TSA) was first conducted to provide robust estimates of the correlation between aldehyde dehydrogenase 1 (ALDH1) and Nestin and clinical outcomes of advanced cancer patients.

Methods

Hazard ratios (HRs) with 95% confidence intervals (CIs) were summarized for overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), cancer-specific survival (CSS), relapse/recurrence-free survival (RFS), and metastasis-free survival (MFS) from multivariable analysis. TSA was performed to control for random errors.

Results

A total of 20 studies with 2050 patients (ALDH1: 15 studies with 1557 patients and Nestin: 5 studies with 493 patients) were identified. ALDH1 (HR = 2.28, p < 0.001) and Nestin (HR = 2.39, p < 0.001) were associated with a worse OS, as confirmed by TSA. Nestin positivity was linked to a poor PFS (HR = 2.08, p < 0.001), but ALDH1 was not linked to DFS, RFS, MFS, or PFS, and TSA showed that more studies were needed. Subgroup analysis by tumor type indicated that ALDH1 positivity may be associated with shorter OS in breast, head and neck cancers, but there was no association with colorectal cancer. Subgroup analysis by study source showed that ALDH1 positivity was correlated with a worse OS for Japanese (HR = 1.94, p = 0.002) and European patients (HR = 4.15, p < 0.001), but there was no association for Chinese patients. Subgroup analysis by survival rate showed that ALDH1 positivity correlated with poor OS at ⩾ 5 years (HR = 2.33, p < 0.001) or 10 years (HR = 1.76, p = 0.038).

Conclusions

ALDH1 may be more valuable as an effective therapeutic target than Nestin for improving the long-term survival rate of advanced cancer. Additional prospective clinical trials are needed across different cancer types.

Identifying and targeting cancer stem cells in leiomyosarcoma: prognostic impact and role to overcome secondary resistance to PI3K/mTOR inhibition

Background

Leiomyosarcoma (LMS) is one of the most frequent soft tissue sarcoma subtypes and is characterized by a consistent deregulation of the PI3K/mTOR pathway. Cancer stem cells (CSCs) have been poorly studied in soft tissue sarcomas. In this study, we aimed to evaluate the association between CSCs, the outcome of LMS patients, and the resistance to PI3K/mTOR pathway inhibition.

Methods

We investigated the relationships between aldehyde dehydrogenase 1 (ALDH1) expression, a cancer stem cell marker, and the outcome of LMS patients in two independent cohorts. We assessed the impact of CSCs in resistance to PI3K/mTOR pathway inhibition using LMS cell lines, a xenograft mouse model, and human tumor samples.

Results

We found that enhanced ALDH1 activity is a hallmark of LMS stem cells and is an independent prognostic factor. We also identified that secondary resistance to PI3K/mTOR pathway inhibition was associated with the expansion of LMS CSCs. Interestingly, we found that EZH2 inhibition, a catalytic component of polycomb repressive complex which plays a critical role in stem cell maintenance, restored sensitivity to PI3K/mTOR pathway inhibition. Importantly, we confirmed the clinical relevance of our findings by analyzing tumor samples from patients who showed secondary resistance after treatment with a PI3Kα inhibitor.

Conclusions

Altogether, our findings suggest that CSCs have a strong impact on the outcome of patients with LMS and that combining PI3K/mTOR and EZH2 inhibitors may represent a promising strategy in this setting.

Electronic supplementary material

The online version of this article (10.1186/s13045-018-0694-1) contains supplementary material, which is available to authorized users.

Cancer stem-like cells directly participate in vasculogenic mimicry channels in triple-negative breast cancer

Objective

Vasculogenic mimicry (VM) channels that are lined by tumor cells are a functional blood supply in malignant tumors. However, the role of VM-initiating cells remains poorly understood. Cancer stem-like cells (CSCs) are positively correlated with VM. In this study, triple-negative breast cancer (TNBC) enriched with CSCs was used to investigate the relationship between VM and CSCs.

Methods

The expression of several CSC markers was detected by immunohistochemistry in 100 human breast cancer samples. The clinical significance of CSC markers and the relationship between VM, CSCs, breast cancer subtypes, and VM-associated proteins were analyzed. CD133+ and ALDH+ human and mouse TNBC cells were isolated by FACS to examine the ability of VM formation and the spatial relationship between VM and CSCs.

Results

CSCs were associated with TNBC subtype and VM in human invasive breast cancer. CSCs in TNBC MDA-MB-231 cells formed more VM channels and expressed more molecules promoting VM than the non-TNBC MCF-7 cells in vitro. MDA-MB-231 cells that encircled VM channels on Matrigel expressed CD133. Moreover, CSCs were located near VM channels in the 3D reconstructed blood supply system in human TNBC grafts. The CD133+ and ALDH+ cells isolated from TA2 mouse breast cancer formed more VM channels in vivo.

Conclusions

CSCs line VM channels directly. Additionally, CSCs provide more VM-related molecules to synergize VM formation. The signaling pathways that control CSC differentiation may also be potential treatment targets for TNBC.

Aldehyde Dehydrogenase 1 (ALDH1) Promotes the Toxicity of TRAIL in Non-Small Cell Lung Cancer Cells via Post-Transcriptional Regulation of MEK-1 Expression

BACKGROUND/AIM

Tumor Necrosis Factor-Related Apoptosis Inducing Ligand (TRAIL)-based therapies have been used in many human cancers. However, some tumors are resistant to TRAIL-induced cell death. Aldehyde dehydrogenase 1 (ALDH1) is a functional marker for identification of CSCs.

METHODS

In this study, we used the colony formation assay, AnnexinV/ PI double staining and PI staining to detect proliferation, apoptosis and cell cycle in ALDH1+ non-small cell lung cancer (NSCLC) cells with TRAIL treatment. In addition, we established xenograft mouse models to confirm the anti-tumor roles of TRAIL in vivo. Finally, gene array and western blot were used to detect the deeper mechanism of the susceptibility of ALDH1+ NSCLC cells to TRAIL.

RESULTS

We confirmed that TRAIL could inhibit proliferation, and induce apoptosis and G1 arrest in ALDH1+ NSCLC cells. Correspondingly, TRAIL was associated with decreased tumor size and the favorable survival rate of ALDH1+ cells established xenograft mouse models. ALDH1 could increase the death receptors (DR) 4 and DR5 expression in ALDH1+ NSCLC cells via activating MEK/ERK signaling pathway.

CONCLUSION

ALDH1 protein induced MEK-1 mRNA stability and promoted its translation via its 3'UTR.

The prognostic roles of circulating ALDH1+ tumor cell in the patients with non-small cell lung cancer

Circulating tumor cells can provide important diagnostic and prognostic information of the patients with non-small cell lung cancer (NSCLC). Aldehyde dehydrogenase 1 (ALDH1), a cancer stem cell marker, has been used in various tumors, including NSCLC. In the present study, we isolated the circulating ALDH1⁺ tumor cells from the NSCLC patients using ALDH1 as a potential marker. Higher percentage of ALDH1⁺ tumor cells was identified in blood samples from the NSCLC patients compared with normal controls. ALDH1⁺ cells were correlated with the poor prognosis of these patients by using Kaplan–Meier analysis. In the last, the tumorigenic properties of ALDH1⁺ tumor cells were determined in vitro and in vivo by using sphere assay and xenograft tumor mouse models. Our in vitro and in vivo experiments demonstrated that ALDH1 could drive the stemness of circulating NSCLC cells. Circulating ALDH1⁺ cells could be used as a prognostic marker for NSCLC.

YAP regulates ALDH1A1 expression and stem cell property of bladder cancer cells

Background

Yes-associated protein (YAP), a key player of the Hippo pathway, has been identified to have more and more important roles in tumorigenesis and may be an important biomarker for cancer therapy. YAP is important for bladder cancer cell migration, metastasis, and drug resistance; however, its function in bladder cancer stem cells remains unknown.

Purpose

The aim of this work was to examine the expression and role of YAP in bladder cancer stem cells.

Materials and methods

We identified that the expression level of YAP was significantly enriched in bladder cancer stem cells compared to noncancer stem cell population. Moreover, the effect of YAP on stem cell self-renewal was examined in bladder cancer cells by siRNA silencing approach. In addition, we showed that YAP is required for aldehyde dehydrogenase activity in bladder cancer cells.

Results

RNAseq analysis and quantitative real-time PCR results showed that silencing of YAP inhibited the expression of ALDH1A1 gene.

Conclusion

Collectively, our findings for the first time elucidated that YAP serves as a cancer stem cell regulator in bladder cancer, which provided a promising therapy strategy for patients with bladder cancer.