Association between ALDH1+/CD133+ stem-like cells and tumor angiogenesis in invasive ductal breast carcinoma

A novel approach for transforming breast cancer stem cells into endothelial cells

Tumor vascular endothelial cells play a pivotal in the tumor microenvironment, influencing the proliferation, invasion, and metastasis of tumor progression. The present study investigated a novel method for inducing the transformation of breast cancer stem cells into endothelial cells, providing a cellular model investigating anti-angiogenic mechanisms in vitro. The breast cancer cell line MCF-7 was used, and the expression of CD133 was initially detected using flow cytometry. CD133+ breast cancer cells were purified using immunomagnetic bead sorting technology, yielding an MCF-7CD133+ subpopulation. The proliferation ability of these cells was assessed using an MTT assay, while their microsphere formation ability was evaluated using a microsphere formation assay. Post-transformation in an optimized endothelial cell culture medium, expression of endothelial cell markers CD31 and CD105 were detected using flow cytometry. Endothelial cell tube formation assays and DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) assays were employed to analyze the endothelial cell function of the MCF-7CD133+ cells. MDM2/CEN12 gene amplification was detected through fluorescence in situ hybridization (FISH). The MCF-7 breast cancer cell line exhibited 1.7±0.3% trace cells expressing the stem cell surface marker CD133. After anti-CD133 immunomagnetic bead sorting, MCF-7CD133+ and MCF-7CD133- subpopulation cells were obtained, with CD133 expression rates of 85.6±2.8 and 0.18±0.08%, respectively. MTT assay results demonstrated that, after 7 days, the proliferation rate of MCF-7CD133+ cells was significantly higher compared with MCF-7CD133- cells. MCF-7CD133+ subpopulation cells displayed strong stem cell characteristics, growing in suspension in serum-free media and forming tumor cell spheres. In contrast, MCF-7CD133- cells failed to form microspheres. After culturing cells in endothelial cell differentiation and maintenance media, the percentage of MCF-7CD133+ cells before and after endothelial cell culture was 0.3±0.16 and 81.4±8.37% for CD31+ cells and 0.2±0.08 and 83.8±7.24% for CD105+ cells, respectively. Vascular-like structure formation and Ac-LDL phagocytosis with red fluorescence in the tube formation assays confirmed endothelial cell function in the MCF-7CD133+ cells. FISH was used to verify MDM2/CEN12 gene amplification in the induced MCF-7CD133+ cells, indicating tumor cell characteristics. The modified endothelial cell transformation medium effectively induced differentiated tumor stem cells to express vascular endothelial cell markers and exhibit endothelial functions, ideal for in vitro anti-angiogenesis research.

Photodynamic therapy in cancer stem cells - state of the art

Despite significant efforts to control cancer progression and to improve oncology treatment outcomes, recurrence and tumor resistance are frequently observed in cancer patients. These problems are partly related to the presence of cancer stem cells (CSCs). Photodynamic therapy (PDT) has been developed as a therapeutic approach for solid tumors; however, it remains unclear how this therapy can affect CSCs. In this review, we focus on the effects of PDT on CSCs and the possible changes in the CSC population after PDT exposure. Tumor response to PDT varies according to the photosensitizer and light parameters employed, but most studies have reported the successful elimination of CSCs after PDT. However, some studies have reported that CSCs were more resistant to PDT than non-CSCs due to the increased efflux of photosensitizer molecules and the action of autophagy. Additionally, using different PDT approaches to target the CSCs resulted in increased sensitivity, reduction of sphere formation, invasiveness, stem cell phenotype, and improved response to chemotherapy. Lastly, although mainly limited to in vitro studies, PDT, combined with targeted therapies and/or chemotherapy, could successfully target CSCs in different solid tumors and promote the reduction of stemness, suggesting a promising therapeutic approach requiring evaluation in robust pre-clinical studies.

Overexpression of LncRNA MNX1-AS1/PPFIA4 Activates AKT/HIF-1α Signal Pathway to Promote Stemness of Colorectal Adenocarcinoma Cells

Purpose. The purpose of this study was to explore the role of the lncRNA MNX1-AS1 and its related downstream signaling pathways in colorectal adenocarcinoma (COAD). Methods. COAD tissues and cells were prepared and treated with sh-MNX1-AS1, pcDNA-MNX1-AS1, sh-PPFIA4, LY29004, and their controls. CCK8 and colony formation assays were undertaken for evaluating cell proliferation. Tumor cell migratory ability was detected by transwell assay. Apoptosis detection was processed by YO-PRO-1/PI Staining. The regulated relationship between lncRNA MNX1-AS1 and PPFIA4 was confirmed by RIP-ChIP assay. Q-PCR was applied to detect genes related to tumor cell stemness, proliferation, migration, and apoptosis in each group. Finally, a xenograft tumor model was constructed to verify the result in vivo. Results. COAD patients with high expression of the lncRNA MNX1-AS1 have poor prognosis. LncRNA MNX1-AS1 promotes the stemness of COAD cells. PPFIA4 mediates lncRNA MNX1-AS1 expression and affects COAD cell stemness. LncRNA MNX1-AS1 accelerates proliferation and migration, while it suppresses apoptosis. LncRNA MNX1-AS1/PPFIA4 accelerates tumor growth in COAD model. LncRNA MNX1-AS1/PPFIA4 activates the downstream AKT/HIF-1α signaling pathway to promote COAD development. LY29004 significantly inhibits the tumorigenic ability of lncRNA MNX1-AS1 and PPFIA4. Conclusion. LncRNA MNX1-AS1/PPFIA4 activates AKT/HIF-1α signal pathway to promote the stemness of COAD cells, which could be a new target for COAD treatment.

Tumour Stem Cells in Breast Cancer

Tumour stem cells (CSCs) are a self-renewing population that plays important roles in tumour initiation, recurrence, and metastasis. Although the medical literature is extensive, problems with CSC identification and cancer therapy remain. This review provides the main mechanisms of CSC action in breast cancer (BC): CSC markers and signalling pathways, heterogeneity, plasticity, and ecological behaviour. The dynamic heterogeneity of CSCs and the dynamic transitions of CSC⁻ non-CSCs and their significance for metastasis are considered.

Heterogeneity of BCSCs contributes to the metastatic organotropism of breast cancer

Breast cancer is one of the most-common female malignancies with a high risk of relapse and distant metastasis. The distant metastasis of breast cancer exhibits organotropism, including brain, lung, liver and bone. Breast cancer stem cells (BCSCs) are a small population of breast cancer cells with tumor-initiating ability, which participate in regulating distant metastasis in breast cancer. We investigated the heterogeneity of BCSCs according to biomarker status, epithelial or mesenchymal status and other factors. Based on the classical “seed and soil” theory, we explored the effect of BCSCs on the metastatic organotropism in breast cancer at both “seed” and “soil” levels, with BCSCs as the “seed” and BCSCs-related microenvironment as the “soil”. We also summarized current clinical trials, which assessed the safety and efficacy of BCSCs-related therapies. Understanding the role of BCSCs heterogeneity for regulating metastatic organotropism in breast cancer would provide a new insight for the diagnosis and treatment of advanced metastatic breast cancer.

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.

Novel insights into breast cancer progression and metastasis: A multidisciplinary opportunity to transition from biology to clinical oncology

According to the most recent epidemiological studies, breast cancer shows the highest incidence and the second leading cause of death in women. Cancer progression and metastasis are the main events related to poor survival of breast cancer patients. This can be explained by the presence of highly resistant to chemo- and radiotherapy stem cells in many breast tumor tissues. In this context, numerous studies highlighted the possible involvement of epithelial to mesenchymal transition phenomenon as biological program to generate cancer stem cells, and thus participate to both metastatic and drug resistance process. Therefore, the comprehension of mechanisms (both cellular and molecular) involved in breast cancer occurrence and progression can lay the foundation for the development of new diagnostic and therapeutical protocols. In this review, we reported the most important findings in the field of breast cancer highlighting the most recent data concerning breast tumor biology, diagnosis and therapy.

Prognostic value of aldehyde dehydrogenase 1 (ALDH1) in invasive breast carcinomas

Aldehyde dehydrogenase 1 (ALDH1) has been identified as a marker of cancer stem cells in breast cancer (BC). Recent studies showed that ALDH1 expression is correlated with poor prognostic parameters and worse clinical outcome in BC. We evaluated ALDH1 expression by immunohistochemistry in a series of 217 invasive BCs and investigated the correlation between ALDH1 expression and clinicopathological parameters, molecular subtypes (luminal A, luminal B, human epidermal growth factor receptor 2 [HER2] type, and triple-negative BC [TNBC]), and patient survival. There was a significant association between ALDH1 expression and tumor grade (p < 0.001), i.e., the expression of ALDH1 was higher in high-grade tumors. ALDH1 expression was significantly associated with estrogen and progesterone receptor (ER and PR) negativity (p < 0.001) and HER2 positivity (p = 0.001). ALDH1 expression ratios were higher in HER2 type and TNBC. There was a statistically significant correlation between ALDH1 negativity and luminal A subtype (p < 0.001). The overall and disease free survival were shorter in ALDH1+ tumors, although without statistical significance. We confirm that ALDH1 is a potentially important, poor prognostic factor in BC, associated with high histological grade, ER/PR negativity and HER2 positivity. For more accurate results, ALDH1 expression should be evaluated in larger case series including various types/subtypes of BC.

Breast cancer stem cells and the challenges of eradication: a review of novel therapies

Breast cancer is a heterogeneous disease that accounts for 30% of all cancers diagnosed in women and over half a million deaths per year. Cancer stem cells (CSCs) make up a small subpopulation of cells within a tumor, are capable of self-renewal and, are responsible for tumor initiation, formation, and recurrence. Breast CSCs (BCSCs) have been the subject of concentrated research as potential targets for breast cancer therapies. Cell surface markers CD44+/CD24- have been established as minimum biomarkers for BCSCs and the upregulation of CD44 expression has been linked to tumor formation in numerous cancers. Additionally, the deregulation of Notch, Wnt/Frizzled/β-catenin, Hippo, and Hedgehog signaling pathways is believed to be responsible for the formation of CSCs and lead to tumor formation. Tumor heterogeneity is a key feature of therapy resistance and a major challenge. CSCs are predominantly senescent and inherently immune to chemotherapy drugs which rely on an overactive cell cycle. Current therapeutic strategies include targeting CSC signaling pathways that play critical roles in self-renewal and defense. Anti-CD44 antibodies have been shown to induce terminal differentiation in CSCs resulting in a significant decrease in tumor metastasis. Additionally, targeting the tumor microenvironment has been shown to increase the effectiveness of chemotherapy drugs. In this review, we attempt to provide an overview of breast cancer, the stem of its cause, and novel therapies currently being explored.

Cancer stem cell in breast cancer therapeutic resistance

Development of therapeutic resistance and metastasis is a major challenge with current breast cancer (BC) therapy. Mounting evidence suggests that a subpopulation of cancer stem cells (CSCs) contribute to the cancer therapeutic resistance and metastasis, leading to the recurrence and death in patients. Breast cancer stem cells (BCSCs) are not only a consequence of mutations that overactivate the self-renewal ability of normal stem cells or committed progenitors but also a result of the de-differentiation of cancer cells induced by somatic mutations or microenvironmental components under treatment. Eradication of BCSCs may bring hope and relief to patients whose lives are threatened by recurrent BCs. Therefore, a better understanding of the generation, regulatory mechanisms, and identification of CSCs in BC therapeutic resistance and metastasis will be imperative for developing BCSC-targeted strategies. Here we summarize the latest studies about cell surface markers and signalling pathways that sustain the stemness of BCSC and discuss the associations of mechanisms behind these traits with phenotype and behavior changes in BCSCs. More importantly, their implications for future study are also evaluated and potential BCSC-targeted strategies are proposed to break through the limitation of current therapies.

Targeting cancer stem cells in the clinic: Current status and perspectives

Resistance to chemotherapy and cancer relapse are major clinical challenges attributed to a sub population of cancer stem cells (CSCs). The concept of CSCs has been the subject of intense research by the oncology community since evidence for their existence was first published over twenty years ago. Emerging data indicates that they are also able to evade novel therapies such as targeted agents, immunotherapies and anti-angiogenics. The inability to appropriately identify and isolate CSCs is a major hindrance to the field and novel technologies are now being utilized. Agents that target CSC-associated cell surface receptors and signaling pathways have generated promising pre-clinical results and are now entering clinical trial. Here we discuss and evaluate current therapeutic strategies to target CSCs.

Surface Markers for the Identification of Cancer Stem Cells

Cancer stem cells have genetic and functional characteristics that can turn them resistant to standard cancer therapeutic targets. Identification of these cells is challenging and is mostly done by detecting the expression of their antigens in a group of stem cells. Currently, there are a significant number of surface markers available which can detect the cancer stem cells by directly targeting their specific antigens present in cells. These markers possess differential expression patterns and sub-localizations in cancer stem cells when compared to non-neoplastic stem cells and somatic cells. In addition to molecular markers, multiple analytical methods and techniques including functional assays, cell sorting, filtration approaches, and xenotransplantation methods are used to identify cancer stem cells. This chapter will overview the functional significance of cancer stem cells, its biological correlations, specific markers, and detection methods.

Aldehyde dehydrogenase 1 expression is correlated with poor prognosis in breast cancer

Breast cancer (BC) is one of the most common cancers worldwide, and is a major cause of death in women. Aldehyde dehydrogenase 1 (ALDH1) is a marker of stem cells and cancer stem cells, and its activity correlates with the outcome of various tumors, including BC. This study aimed to analyze the relationship between ALDH1 expression and clinicopathological characters in BC and the prognostic significance of ALDH1.We used quantitative reverse-transcription PCR (qRT-PCR) to detect ALDHA1 mRNA levels in 25 fresh frozen BC samples and matched noncancerous samples. Immunohistochemistry on tissue microarrays was used to analyze protein expression in 137 paraffin-embedded BC tissues and corresponding noncancerous tissues. STATA 16.0 software was used for statistical analysis.The results suggested that levels of both ALDH1 mRNA and protein in BC were significantly higher than in corresponding adjacent breast samples (3.856 ± 0.3442 vs 1.385 ± 0.1534, P < .001; 52.6% vs 25.5%, P < .001, respectively). ALDH1 protein expression was also significantly associated with histological grade (P  =  .017), tumor size (P  =  .017), and tumor-node-metastasis (TNM) stage (P  =  .038). Multivariate analysis using the Cox regression model demonstrated that ALDH1 expression (P  =  .024), molecular typing (P  =  .046), and TNM classification (P  =  .034) were independent predictive factors for the outcome of BC. Kaplan-Meier analysis and the log-rank test indicated that patients with high ALDH1 expression, triple-negative BC, and advanced TNM stage had a reduced overall survival time.These data suggest that ALDH1 could be used as a prognostic factor for BC and may provide a useful therapeutic target in the treatment of BC.

Overexpression of syndecan-1, MUC-1, and putative stem cell markers in breast cancer leptomeningeal metastasis: a cerebrospinal fluid flow cytometry study

Background

Cancer is a mosaic of tumor cell subpopulations, where only a minority is responsible for disease recurrence and cancer invasiveness. We focused on one of the most aggressive circulating tumor cells (CTCs) which, from the primitive tumor, spreads to the central nervous system (CNS), evaluating the expression of prognostic and putative cancer stem cell markers in breast cancer (BC) leptomeningeal metastasis (LM).

Methods

Flow cytometry immunophenotypic analysis of cerebrospinal fluid (CSF) samples (4.5 ml) was performed in 13 consecutive cases of BCLM. Syndecan-1 (CD138), MUC-1 (CD227) CD45, CD34, and the putative cancer stem cell markers CD15, CD24, CD44, and CD133 surface expression were evaluated on CSF floating tumor cells. The tumor-associated leukocyte population was also characterized.

Results

Despite a low absolute cell number (8 cell/μl, range 1–86), the flow cytometry characterization was successfully conducted in all the samples. Syndecan-1 and MUC-1 overexpression was documented on BC cells in all the samples analyzed; CD44, CD24, CD15, and CD133 in 77%, 75%, 70%, and 45% of cases, respectively. A strong syndecan-1 and MUC-1 expression was also documented by immunohistochemistry on primary breast cancer tissues, performed in four patients. The CSF tumor population was flanked by T lymphocytes, with a different immunophenotype between the CSF and peripheral blood samples (P ≤ 0.02).

Conclusions

Flow cytometry can be successfully employed for solid tumor LM characterization even in CSF samples with low cell count. This in vivo study documents that CSF floating BC cells overexpress prognostic and putative cancer stem cell biomarkers related to tumor invasiveness, potentially representing a molecular target for circulating tumor cell detection and LM treatment monitoring, as well as a primary target for innovative treatment strategies. The T lymphocyte infiltration, documented in all CSF samples, suggests a possible involvement of the CNS lymphatic system in both lymphoid and cancer cell migration into and out of the meninges, supporting the extension of a new form of cellular immunotherapy to LM. Due to the small number of cases, validation on large cohorts of patients are warranted to confirm these findings and to evaluate the impact and value of these results for diagnosis and management of LM.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0827-4) contains supplementary material, which is available to authorized users.

Clinicopathological characteristics and prognostic value of cancer stem cell marker CD133 in breast cancer: a meta-analysis

Background

The association of CD133 overexpression with clinicopathological significance and prognosis in patients with breast cancer remains controversial. We thus performed a meta-analysis to evaluate the role of CD133 expression in the development and prognosis of breast cancer.

Methods

The databases PubMed, Embase, and Cochrane Library (updated to August 1, 2016) were searched. Pooled odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals (95% CI) were used to evaluate the impact of CD133 expression on clinicopathological features, overall survival, and disease-free survival.

Results

A total of 1,734 patients from 13 studies were subject to final analysis. The results showed a significant association between overexpression of CD133 and estrogen receptor status (OR 0.35, 95% CI 0.18–0.70), progesterone receptor status (OR 0.56, 95% CI 0.43–0.74), human epidermal growth factor-2 status (OR 1.81, 95% CI 1.33–2.45), lymph node metastasis (OR 1.98, 95% CI 1.34–2.92), and tumor histological grade (OR 1.79, 95% CI 1.26–2.54) in breast cancer. However, no significant correlation was found between upregulation of CD133 expression and onset age (OR 1.03, 95% CI 0.70–1.53) or tumor size (OR 1.29, 95% CI 0.80–2.09). Moreover, CD133-positive breast cancer patients had a higher risk of mortality (HR 1.91, 95% CI 1.21–3.03) and disease progression (HR 2.70, 95% CI 1.05–6.95).

Conclusion

This meta-analysis suggested that CD133 might be a predictor of clinical outcomes as well as prognosis and could be a potentially new gene therapy target for breast cancer patients.

Engineered Breast Cancer Cell Spheroids Reproduce Biologic Properties of Solid Tumors

Solid tumors develop as 3D tissue constructs. As tumors grow larger, spatial gradients of nutrients and oxygen and inadequate diffusive supply to cells distant from vasculature develops. Hypoxia initiates signaling and transcriptional alterations to promote survival of cancer cells and generation of cancer stem cells (CSCs) that have self-renewal and tumor-initiation capabilities. Both hypoxia and CSCs are associated with resistance to therapies and tumor relapse. This study demonstrates that 3D cancer cell models, known as tumor spheroids, generated with a polymeric aqueous two-phase system (ATPS) technology capture these important biological processes. Similar to solid tumors, spheroids of triple negative breast cancer cells deposit major extracellular matrix proteins. The molecular analysis establishes presence of hypoxic cells in the core region and expression of CSC gene and protein markers including CD24, CD133, and Nanog. Importantly, these spheroids resist treatment with chemotherapy drugs. A combination treatment approach using a hypoxia-activated prodrug, TH-302, and a chemotherapy drug, doxorubicin, successfully targets drug resistant spheroids. This study demonstrates that ATPS spheroids recapitulate important biological and functional properties of solid tumors and provide a unique model for studies in cancer research.

A Case Report of Local Recurrence Developing 24 Years After Mastectomy for Breast Cancer Recurrence From Breast Cancer After 24 Years

INTRODUCTION

Breast cancer is a commonly diagnosed cancer, in which most patients' metastases (about 75%) occurred in 5 years after the initial diagnosis, especially in 3 years. Recrudescence exceeding 20 years is rarely reported in the past several decades.Case information: A 68-year-old female patient presented with breast cancer in which 3 focal increased 18F-fluorodeoxyglucose uptake in the right supraclavicular lymph node, the mediastinum and sternum were found on positron emission tomography and computed tomography. Then we learned that the patient had suffered from breast cancer and been given a right-sided mastectomy 24 years ago. Histopathology from the mediastinum revealed metastatic, moderately differentiated breast adenomatous cell carcinoma.

CONCLUSION

We report this late recurrence of breast cancer 24 years following mastectomy, suggesting that possible recurrence of this disease with a 24-year latency period should be taken into consideration.