Clinical-pathologic significance of cancer stem cell marker expression in familial breast cancers

Efficient and Discriminative Isolation of Circulating Cancer Stem Cells and Non-Stem-like Circulating Tumor Cells Using a Click-Handle-Loaded M13 Phage-Based Surface

Circulating tumor cells (CTCs) are crucial for cancer research and clinical applications, with circulating cancer stem cells (cCSCs) being a rare but key subpopulation responsible for metastasis, recurrence, and therapy resistance. Current limitations in efficiently isolating these cells, particularly distinguishing cCSCs from non-stem-like CTCs (nsCTCs), hinder our understanding of cancer progression and precision medicine strategies. Herein, we developed a novel CTC isolation approach that integrates cell metabolic chemical tagging with a click-handle-loaded M13 phage-based surface (CHPhace). The multivalent nature of flexible M13 nanofibers, featuring thousands of modification sites for click reactions, significantly enhances CTC capture across diverse tumor types. Leveraging the unique slow-cycling characteristic of cCSCs, CHPhace demonstrated selective cCSCs isolation through metabolic labeling and demetabolism processes. The robust performance of CHPhace allows efficient isolation of both cCSCs and nsCTCs from complex blood sample matrices, achieving capture efficiencies exceeding 80%. This approach represents a promising tool for advancing our understanding of cancer progression and enhancing precision in clinical diagnosis and cancer prognosis.

Clinicopathologic Correlation of CD44 + /CD24 - Expression in Breast Cancer: a Report from Tertiary Care Medical University in India

CD44 + /CD24 - phenotype has been associated with stem cell-like characteristics with enhanced invasive properties, radiation resistance, and with distinct genetic profiles suggesting a correlation to adverse prognosis in western literature. The aim of this study was to study CD44 + /CD24 - phenotype as an adverse prognostic marker in Indian breast cancer patients. N = 61 breast cancer patients included in a tertiary care facility in India were evaluated for receptor studies (estrogen receptor ER, progesterone receptor PR, Herceptin antibody Her2 neu receptor, CD44 & CD24 stem cell markers). CD44 + /CD24 - phenotype was statistically related to adverse factors like estrogen and progesterone receptors non-expression, her 2 neu expression, and triple-negative breast cancer. Of the 39 patients with ER-ve status, 33 (84.6%) were found to have CD44 + /CD24 - phenotype and 82.5% of all the CD 44 + /CD24 - patients were ER negative (p = 0.001). Thirty-four (75.5%) of the PR-ve patients showed the CD44 + /CD24 - phenotype, and of all the CD 44 + /CD24 - patients, 85% of were PR negative (p = 0.006). Thirty-six (75%) of Her-2-Neu + ve were CD44 + /CD24 - . Approximately 90% of the Her 2 Neu patients expressed CD44 + /CD24 - and 76.9% of all the triple-negative patients were found to be CD44 + /CD24 - expression (p = 0.001). CD44 + /CD24 - had a significant association with adverse prognostic factors like stage of disease, hormonal receptor status, and molecular subtypes in Indian breast cancer patients like the Western data.

Prognosis assessment of CD44+/CD24- in breast cancer patients: a systematic review and meta-analysis

PURPOSE

This meta-analysis investigated the relationships between the CD44⁺/CD24^- phenotype and tumor size, lymph node metastasis, distant metastasis, disease-free survival (DFS), and overall survival (OS) in 8036 postoperative breast cancer patients enrolled in 23 studies.

METHODS

A literature search of PubMed, Medline, Cochrane, Embase, and PMC was conducted to identify eligible studies. The combined odds ratios (ORs) and 95% confidence intervals (95% CIs) were analyzed to evaluate the relationships between the CD44⁺/CD24^- phenotype and the pathological and biological characteristics of breast cancer patients, and the combined hazard ratios (HRs) and 95% CIs were calculated to evaluate the relationships between CD44⁺/CD24^- and DFS and OS of breast cancer patients using Stata12.0 software.

RESULTS

The CD44⁺/CD24^- phenotype were not related to the tumor size (tumor size > 2.0 vs ≤ 2.0 cm, combined OR = 0.98, 95% CI 0.68-1.34, p = 0.792) and did not promote lymph node metastasis (lymph node metastasis vs. no lymph node metastasis, OR = 0.92, 95% CI 0.67-1.27, p = 0.626) and distant metastasis (distant metastasis vs no distant metastasis, combined OR = 3.88, 95% CI 0.93-16.24, p = 0.064). The CD44⁺/CD24^- phenotype was negatively correlated with postoperative DFS (HR = 1.67, 95% CI 1.35-2.07, p < 0.00001) and OS (combined HR = 1.52, 95% CI 1.21-1.91, p = 0.0004).

CONCLUSION

These results suggested expression of the CD44⁺/CD24^- phenotype cannot be used as a reliable indicator of the tumor size, lymph node metastasis, and distant metastasis, however, it can be used be a potential therapeutic targets of DFS, OS in breast cancer patients.

The Breast Cancer Stem Cells Traits and Drug Resistance

Drug resistance is a major challenge in breast cancer (BC) treatment at present. Accumulating studies indicate that breast cancer stem cells (BCSCs) are responsible for the BC drugs resistance, causing relapse and metastasis in BC patients. Thus, BCSCs elimination could reverse drug resistance and improve drug efficacy to benefit BC patients. Consequently, mastering the knowledge on the proliferation, resistance mechanisms, and separation of BCSCs in BC therapy is extremely helpful for BCSCs-targeted therapeutic strategies. Herein, we summarize the principal BCSCs surface markers and signaling pathways, and list the BCSCs-related drug resistance mechanisms in chemotherapy (CT), endocrine therapy (ET), and targeted therapy (TT), and display therapeutic strategies for targeting BCSCs to reverse drug resistance in BC. Even more importantly, more attention should be paid to studies on BCSC-targeted strategies to overcome the drug resistant dilemma of clinical therapies in the future.

Heterogeneity of Stemlike Circulating Tumor Cells in Invasive Breast Cancer

The presence of stem and epithelial–mesenchymal-transition (EMT) features in circulating tumor cells (CTCs) determines their invasiveness, adaptability to the microenvironment, and resistance to proapoptotic signals and chemotherapy. It also allows them to fulfil the role of metastatic “seeds”. We evaluated the heterogeneity of stem CTCs by their CD44, ALDH1, and CD133 expression depending on N-cadherin expression in breast-cancer patients. A total of 38 female patients were selected for this study. CTC phenotypes were determined by flow cytometry before any type of treatment. Multiplex immunofluorescence was used for the evaluation of tumor-cell heterogeneity in primary lesions. In patients who had CD44-CD24- CTCs, a subset of cells with the expression of other stem-cell markers (CD133 and ALDH1) were detected. Expression of CD133 and/or ALDH1 may be associated with expression of N-cadherin: all populations of N-cadherin+ CTCs demonstrate stem features; in the absence of N-cadherin expression, true nonstem (CD44-CD24-CD133-ALDH1-) cells are found. The heterogeneity of stem marker expression in CTCs was observed regardless of N-cadherin expression. In our study, stromal cell-derived factor-1 (SDF-1) receptor expression in CTCs did not depend on stemlike traits, but was instead associated with N-cadherin expression. Subpopulations of tumor cells, detected both in tumors and blood, were identified. Breast cancer was characterized by pronounced interpersonal and intrapersonal heterogeneity of CTCs by the presence and combination of various stem features and N-cadherin expression. To complete the characterization of stemlike features of CTCs, we suggest the simultaneous use of the three stem markers.

Detection of Putative Stem-cell Markers in Invasive Ductal Carcinoma of the Breast by Immunohistochemistry: Does It Improve Prognostic/Predictive Assessments?

Introduction:

Experimental evidences from the last 2 decades supports the existence of a special type of neoplastic cell with stem-like features [cancer stem cell (CSC)] and their role in the pathophysiology and therapeutic resistance of breast cancer. However, their clinical value in human breast cancer has not been fully determined.

Materials and Methods:

An immunohistochemistry panel of 10 putative CSC markers (CD34, C-KIT, CD10, SOX-2, OCT 3/4, p63, CD24, CD44, CD133, and ESA/EPCAM) was applied to 74 cases of breast cancer, followed in a Regional Cancer Center of Minas Gerais State, Brazil, from 2004 to 2006. Possible associations between CSC markers and classic variables of clinicopathologic relevance were investigated.

Results:

The most frequently positive CSC markers were CD44, CD24, CD133, and ESA (the others were present in <15% of the cases). Two CSC profiles were defined: CD24⁻/CD44⁺ (CSC-1) and CD133⁺/ESA⁺ (CSC-2). CSC-1 was significantly associated to patients older than 40 years, tumors of <2.0 cm in diameter, early clinical stages (P<0.05), and increased death risk of 4 times (P=0.03; 95% confidence interval, 1.09-14.41). CSC-2 was related to increased relapse risk of 3.75 times (P=0.04; 95% confidence interval, 1.02-13.69).

Conclusion:

The detection of the most frequently positive CSC markers by immunohistochemistry is of clinicopathologic and prognostic relevance.

Multi-Omics Characterization of the Spontaneous Mesenchymal-Epithelial Transition in the PMC42 Breast Cancer Cell Lines

Epithelial-mesenchymal plasticity (EMP), encompassing epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET), are considered critical events for cancer metastasis. We investigated chromosomal heterogeneity and chromosomal instability (CIN) profiles of two sister PMC42 breast cancer (BC) cell lines to assess the relationship between their karyotypes and EMP phenotypic plasticity. Karyotyping by GTG banding and exome sequencing were aligned with SWATH quantitative proteomics and existing RNA-sequencing data from the two PMC42 cell lines; the mesenchymal, parental PMC42-ET cell line and the spontaneously epithelially shifted PMC42-LA daughter cell line. These morphologically distinct PMC42 cell lines were also compared with five other BC cell lines (MDA-MB-231, SUM-159, T47D, MCF-7 and MDA-MB-468) for their expression of EMP and cell surface markers, and stemness and metabolic profiles. The findings suggest that the epithelially shifted cell line has a significantly altered ploidy of chromosomes 3 and 13, which is reflected in their transcriptomic and proteomic expression profiles. Loss of the TGFβR2 gene from chromosome 3 in the epithelial daughter cell line inhibits its EMT induction by TGF-β stimulus. Thus, integrative 'omics' characterization established that the PMC42 system is a relevant MET model and provides insights into the regulation of phenotypic plasticity in breast cancer.

Targeting Stemness: Implications for Precision Medicine in Breast Cancer

The genomic landscape of breast cancer has been delineated in recent years. Advances in molecular characterization and targeting strategies are making it feasible to integrate clinical, genome-based and phenotype-based diagnostic and therapeutic methods and apply them to individual patient in the era of precision medicine. Cancer stem cells (CSCs) are a subpopulation in the tumor which have the capability of self-renewal and differentiation. Breast CSCs have important clinical implications as they account for tumor initiation, maintenance, metastasis, therapy resistance, and relapse. In this chapter, we will introduce approaches used to characterize breast CSCs, crucial pathways involved in regulating cancer stemness, and implications of breast CSCs in the precision diagnosis and treatment of breast cancer. We will also discuss novel compounds and therapeutic strategies that selectively target breast CSCs. Integration of breast CSC-related molecular diagnosis and targeted therapy into the clinical workflow of precision medicine has the potential to deliver more effective treatment to breast cancer patients.

BRCA1 through Its E3 Ligase Activity Regulates the Transcription Factor Oct1 and Carbohydrate Metabolism

The tumor suppressor BRCA1 regulates the DNA damage response (DDR) and other processes that remain incompletely defined. Among these, BRCA1 heterodimerizes with BARD1 to ubiquitylate targets via its N-terminal E3 ligase activity. Here, it is demonstrated that BRCA1 promotes oxidative metabolism by degrading Oct1 (POU2F1), a transcription factor with proglycolytic and tumorigenic effects. BRCA1 E3 ubiquitin ligase mutation skews cells toward a glycolytic metabolic profile while elevating Oct1 protein. CRISPR-mediated Oct1 deletion reverts the glycolytic phenotype. RNA sequencing (RNAseq) confirms deregulation of metabolic genes downstream of Oct1. BRCA1 mediates Oct1 ubiquitylation and degradation, and mutation of two ubiquitylated Oct1 lysines insulates the protein against BRCA1-mediated destabilization. Oct1 deletion in MCF-7 breast cancer cells does not perturb growth in standard culture, but inhibits growth in soft agar and xenograft assays. In primary breast cancer clinical specimens, Oct1 protein levels correlate positively with tumor aggressiveness and inversely with BRCA1. These results identify BRCA1 as an Oct1 ubiquitin ligase that catalyzes Oct1 degradation to promote oxidative metabolism and restrict tumorigenicity. Mol Cancer Res; 16(3); 439-52. ©2018 AACR.

The prognostic and predictive value of the lymphocyte to monocyte ratio in luminal-type breast cancer patients treated with CEF chemotherapy

Several reports have suggested that peripheral blood-based parameters are associated with host immunity response, which is an essential component of the pathogenesis and progression of cancer. The purpose of the present study was to identify the prognostic significance of various peripheral blood-based biomarkers and to determine the optimal cut-off value suitable for luminal breast cancer patients. We found that lymphocyte-to-monocyte ratio (LMR) was significant prognostic predictors. And the patients with a CEF regimen and LMR ratio ≥ 5.2 gained a good prognosis. This study suggested that the LMR could be regarded as an independent prognostic factor in luminal breast cancer patients. The elevated LMR level also had enhanced 5-fluorouracil sensitivity in luminal breast cancer patients.

CD44+/CD24- phenotype predicts a poor prognosis in triple-negative breast cancer

Cancer stem cells are enriched in triple-negative breast cancer (TNBC) tumor tissues, which present strong capacities of proliferation and tumorigenicity. The present study detected the distribution of cancer stem cell markers cluster of differentiation (CD)44/CD24 and analyzed the clinical outcomes of different CD44/CD24 phenotypes in patients with TNBC. Multivariate Cox regression analyses were performed with regard to the prognostic value of cancer stem cell markers CD44/CD24, aldehyde dehydrogenase 1 and other baseline clinical characteristics, including tumor size, lymph node involved, adjuvant chemotherapy, Ki-67, breast cancer susceptibility gene 1, cellular tumor antigen p53, vimentin and basal-like status. The multivariate analyses showed that three of these factors, CD44/CD24 phenotype, basal-like status and number of lymph nodes involved, had an impact on overall survival. Furthermore, patients with CD44⁺/CD24^- phenotype, basal-like tumors and ≥4 lymph nodes involved had a significantly worse prognosis. The expression of CD44 and CD24 was detected by double-staining immunohistochemistry, which can locate cancer stem cells individually. Overall, the present results indicated that CD44/CD24 status evaluated by double-staining immunohistochemistry constitutes an independent prognostic factor for TNBC.

MicroRNA-34 dysregulation in gastric cancer and gastric cancer stem cell

Gastric cancer is a major cause of cancer mortality worldwide, with a low survival rate for patients with advanced forms of the disease. Over the recent decades, the investigation of the pathophysiological mechanisms of tumourigenesis has opened promising avenues to understand some of the complexities of cancer treatment. However, tumour regeneration and metastasis impose great difficulty for gastric cancer cure. In recent years, cancer stem cells - a small subset of tumour cells in many cancers - have become a major focus of cancer research. Cancer stem cells are capable of self-renewal and are known to be responsible for tumour initiation, metastasis, therapy resistance and cancer recurrence. Recent studies have revealed the key role of microRNAs - small noncoding RNAs regulating gene expression - in these processes. MicroRNAs play crucial roles in the regulation of a wide range of biological processes in a post-transcriptional manner, though their expression is dysregulated in most malignancies, including gastric cancer. In this article, we review the consequences of aberrant expression of microRNA-34 in cancer and cancer stem cells, with a specific focus on the miR-34 dysregulation in gastric cancer and gastric cancer stem cells. We address the critical effects of the aberrant expression of miR-34 and its target genes in maintaining cancer stem cell properties. Information collection and discussion about the advancements in gastric cancer stem cells and microRNAs can be useful for providing novel insights into patient treatment.

Prognostic significance of CD24 and CD44 in breast cancer: a meta-analysis

OBJECTIVE

Numerous studies have focused on the prognostic roles of CD24 and CD44 in breast cancer, but the results have been equivocal. The aim of this study was to gain better insight into the relationship between expression of CD24 and of CD44, either alone or in combination, and prognostic parameters in breast cancer.

METHODS

Publications addressing the associations of CD24 or CD44 expression with survival outcome in breast cancer were selected for the meta-analysis according to defined criteria. Studies were pooled and odds ratios (ORs) or hazard ratios (HRs) were calculated. Publication bias and sensitivity analyses were also conducted.

RESULTS

Sixteen studies comprising 5,697 breast cancer cases were included in our meta-analysis. Overall, CD24 overexpression was significantly associated with histological grade (OR = 1.52; 95% CI 1.12-2.06, p = 0.007), stage (OR = 1.74; 95% CI 1.27-2.40, p<0.001), shortened overall survival (HR = 1.48; 95% CI 1.21-1.80, p<0.001) and disease-free survival (HR 1.45, 95% CI 1.19-1.76, p<0.001), while no such association was observed when we limited our analysis to CD44 and CD44+/CD24- phenotypes. Subgroup analyses for CD24 according to the studies categorized by ethnicity, staining patterns and follow-up period were also conducted, and supported the stability of the prognostic role of CD24.

CONCLUSIONS

Our study demonstrated that the putative stem cell marker CD24 was significantly associated with worse survival based on the obtained data. In particular, CD24 may play a role in tumorigenesis and cancer progression. However, further large-scale studies are needed to confirm these findings.

Molecular characterization of CD44+/CD24-/Ck+/CD45- cells in benign and malignant breast lesions

Breast cancer epithelial cells with the CD44⁺/CD24^-/low phenotype possess tumor-initiating cells and epithelial-mesenchymal transition (EMT) capacity. Massive parallel sequencing can be an interesting approach to deepen the molecular characterization of these cells. We characterized CD44⁺/CD24^-/cytokeratin(Ck)⁺/CD45^- cells isolated through flow cytometry from 43 biopsy and 6 mastectomy samples harboring different benign and malignant breast lesions. The Ion Torrent Ampliseq Cancer Hotspot panel v2 (CHPv2) was used for the identification of somatic mutations in the DNA extracted from isolated CD44⁺/CD24^-/Ck⁺/CD45^- cells. E-Cadherin and vimentin immunohistochemistry was performed on sections from the corresponding formalin-fixed, paraffin-embedded (FFPE) blocks. The percentage of CD44⁺/CD24^-/Ck⁺/CD45^- cells increased significantly from non-malignant to malignant lesions and in association with a significant increase in the expression of vimentin. Non-malignant lesions harbored only a single-nucleotide polymorphism (SNP). Mutations in the tumor suppressor p53 (TP53), NOTCH homolog 1 (NOTCH1), phosphatase and tensin homolog (PTEN), and v-akt murine thymoma viral oncogene homolog 1 (AKT1) genes were found in isolated CD44⁺/CD24^-/Ck⁺/CD45^- cells from ductal carcinomas in situ (DCIS). Additional mutations in the colony-stimulating factor 1 receptor (CSF1R), ret proto-oncogene (RET), and TP53 genes were also identified in invasive ductal carcinomas (IDCs). The use of massive parallel sequencing technology for this type of application revealed to be extremely effective even when using small amounts of DNA extracted from a low number of cells. Additional studies are now required using larger cohorts to design an appropriate mutational profile for this phenotype.

Claudin-Low Breast Cancer; Clinical & Pathological Characteristics

Claudin-low breast cancer is a molecular type of breast cancer originally identified by gene expression profiling and reportedly associated with poor survival. Claudin-low tumors have been recognised to preferentially display a triple-negative phenotype, however only a minority of triple-negative breast cancers are claudin-low. We sought to identify an immunohistochemical profile for claudin-low tumors that could facilitate their identification in formalin fixed paraffin embedded tumor material. First, an in silico collection of ~1600 human breast cancer expression profiles was assembled and all claudin-low tumors identified. Second, genes differentially expressed between claudin-low tumors and all other molecular subtypes of breast cancer were identified. Third, a number of these top differentially expressed genes were tested using immunohistochemistry for expression in a diverse panel of breast cancer cell lines to determine their specificity for claudin-low tumors. Finally, the immunohistochemical panel found to be most characteristic of claudin-low tumors was examined in a cohort of 942 formalin fixed paraffin embedded human breast cancers with >10 years clinical follow-up to evaluate the clinico-pathologic and survival characteristics of this tumor subtype. Using this approach we determined that claudin-low breast cancer is typically negative for ER, PR, HER2, claudin 3, claudin 4, claudin 7 and E-cadherin. Claudin-low tumors identified with this immunohistochemical panel, were associated with young age of onset, higher tumor grade, larger tumor size, extensive lymphocytic infiltrate and a circumscribed tumor margin. Patients with claudin-low tumors had a worse overall survival when compared to patients with luminal A type breast cancer. Interestingly, claudin-low tumors were associated with a low local recurrence rate following breast conserving therapy. In conclusion, a limited panel of antibodies can facilitate the identification of claudin-low tumors. Furthermore, claudin-low tumors identified in this manner display similar clinical, pathologic and survival characteristics to claudin-low tumors identified from fresh frozen tumor material using gene expression profiling.

The role of cancer stem cells in tumor heterogeneity and resistance to therapy

Cancer is a heterogenous disease displaying marked inter- and intra-tumoral diversity. The existence of cancer stem cells (CSCs) has been experimentally demonstrated in a number of cancer types as a subpopulation of tumor cells that drives the tumorigenic and metastatic properties of the entire cancer. Thus, eradication of the CSC population is critical for the complete ablation of a tumor. This is, however, confounded by the inherent resistance of CSCs to standard anticancer therapies, eventually leading to the outgrowth of resistant tumor cells and relapse in patients. The cellular mechanisms of therapy resistance in CSCs are ascribed to several factors including a state of quiescence, an enhanced DNA damage response and active repair mechanisms, up-regulated expression of drug efflux transporters, as well as the activation of pro-survival signaling pathways and inactivation of apoptotic signaling. Understanding the mechanisms underlying the acquisition of resistance to therapy may hold the key to targeting the CSC population.

Breast cancer stem cells expressing different stem cell markers exhibit distinct biological characteristics

Identification and isolation of breast cancer stem cells (CSCs) based on CD44/CD24 expression and/or enzymatic activity of aldehyde dehydrogenase 1 (ALDH1). However, the differences among the CD44+/CD24‑/low cells, ALDH1+ cells and the overlap between the sub‑populations have not been frequently investigated. Thus, it is imperative to improve the understanding of breast CSC with different stem markers. CD44+/CD24‑/low, ALDH1+ and ALDH1+CD44+/CD24‑/low cell populations were isolated from fresh breast cancer tissues and analyzed by flow cytometry and immunofluorescence. Mammosphere formation, cell proliferation assay and Transwell experiments, were used to analyze self‑renewal, proliferation and invasion, respectively, for each sub‑population. Finally, in vivo experimentation in mice was performed to evaluate the tumorigenic abilities of the sub‑populations. The sub‑populations of CD44+/CD24‑/low, ALDH1+ and ALDH1+CD44+/CD24‑/low in human breast cancer cells, represented the 7.2, 4.6 and 1.5% of the total tumor cell population, respectively. ALDH1+CD44+/CD24‑/low cells had the strongest ability of self‑renewal, invasion, proliferation and tumorigenicity compared with the other sub‑populations (P<0.05). In conclusion, different phenotypes of CD44+/CD24‑/low, ALDH1+ and ALDH1+CD44+/CD24‑/low were isolated and demonstrated that breast CSCs are heterogeneous, and they exhibit distinct biological characteristics. As ALDH1+CD44+/CD24‑/low cells demonstrated the strongest stem‑like properties, it may be a useful specific stem cell marker. The utilization of more reliable biomarkers to distinguish the breast CSC pool will be important for the development of specific target therapies for breast cancer.

The Oct1 transcription factor and epithelial malignancies: Old protein learns new tricks

The metazoan-specific POU domain transcription factor family comprises activities underpinning developmental processes such as embryonic pluripotency and neuronal specification. Some POU family proteins efficiently bind an 8-bp DNA element known as the octamer motif. These proteins are known as Oct transcription factors. Oct1/POU2F1 is the only widely expressed POU factor. Unlike other POU factors it controls no specific developmental or organ system. Oct1 was originally described to operate at target genes associated with proliferation and immune modulation, but more recent results additionally identify targets associated with oxidative and cytotoxic stress resistance, metabolic regulation, stem cell function and other unexpected processes. Oct1 is pro-oncogenic in multiple contexts, and several recent reports provide broad evidence that Oct1 has prognostic and therapeutic value in multiple epithelial tumor settings. This review focuses on established and emerging roles of Oct1 in epithelial tumors, with an emphasis on mechanisms of transcription regulation by Oct1 that may underpin these findings. This article is part of a Special Issue entitled: The Oct Transcription Factor Family, edited by Dr. Dean Tantin.

Flubendazole, FDA-approved anthelmintic, targets breast cancer stem-like cells

Cancer stem-like cell (CS-like cell) is considered to be responsible for recurrence and drug resistance events in breast cancer, which makes it a potential target for novel cancer therapeutic strategy. The FDA approved flubendazole, has been widely used in the treatment of intestinal parasites. Here, we demonstrated a novel effect of flubendazole on breast CS-like cells. Flubendazole inhibited breast cancer cells proliferation in dose- and time-dependent manner and delayed tumor growth in xenograft models by intraperitoneal injection. Importantly, flubendazole reduced CD44^high/CD24^low subpopulation and suppressed the formation of mammosphere and the expression of self-renewal related genes including c-myc, oct4, sox2, nanog and cyclinD1. Moreover, we found that flubendazole induced cell differentiation and inhibited cell migration. Consistently, flubendazole reduced mesenchymal markers (β-catenin, N-cadherin and Vimentin) expression and induced epithelial and differentiation marker (Keratin 18) expression in breast cancer cells. Mechanism study revealed that flubendazole arrested cell cycle at G2/M phase and induced monopolar spindle formation through inhibiting tubulin polymerization. Furthermore, flubendazole enhanced cytotoxic activity of conventional therapeutic drugs fluorouracil and doxorubicin against breast cancer cells. In conclusion, our findings uncovered a remarkable effect of flubendazole on suppressing breast CS-like cells, indicating a novel utilization of flubendazole in breast cancer therapy.

Quantitative evaluation of ABC transporter-mediated drug resistance based on the determination of the anticancer activity of camptothecin against breast cancer stem cells using TIRF

Total internal reflection fluorescence microscopy (TIRF) and Qdot probe based analytical method for the simultaneous evaluation of the cytotoxic ability of camptothecin and the drug resistance profile upon the inhibition of drug efflux pumps in breast cancer stem cells.

Oct-4 and Nanog promote the epithelial-mesenchymal transition of breast cancer stem cells and are associated with poor prognosis in breast cancer patients

Oct-4 and Nanog in regulating the epithelial-mesenchymal transition (EMT) and metastasis of breast cancer has not been clarified. We found that both Oct-4 and Nanog expression were significantly associated with tumor pathology and poor prognosis in 126 breast cancer patients. Characterization of CD44+CD24-Cancer stem cell(CSC) derived from breast cancer cells indicated that CSC rapidly formed mammospheres and had potent tumorigenicity in vivo. Furthermore, TGF-β up-regulated the expression of Oct-4, Nanog, N-cadherin, vimentin, Slug, and Snail, but down-regulated E-cadherin and cytokeratin 18 expression, demonstrating that CSC underwent EMT. Knockdown of both Oct-4 and Nanog expression inhibited spontaneous changes in the expression of EMT-related genes, while induction of both Oct-4 and Nanog over-expression enhanced spontaneous changes in the expression of EMT-related genes in CSC. However, perturbing alternation of Oct-4 and Nanog expression also modulated TGF-β-induced EMT-related gene expression in CSC. Induction of Oct-4 and Nanog over-expression enhanced the invasiveness of CSC, but knockdown of both Oct-4 and Nanog inhibited the migration of CSC in vitro. Our data suggest that both Oct-4 and Nanog may serve as biomarkers for evaluating breast cancer prognosis. Our findings indicate that Oct-4 and Nanog positively regulate the EMT process, contributing to breast cancer metastasis.

Breast Cancer Stem Cell Correlates as Predicative Factors for Radiation Therapy

In today's era of personalized medicine, the use of radiation therapy for breast cancer is still tailored to the type of surgery and the stage of the cancer. The future of breast radiation oncology would hopefully entail selecting patients for whom there is a clear benefit for the use of radiation therapy. To get to this point we need reliable predictors of radiation response. Cancer stem cells have been correlated to radiation resistance and outcome for patients with breast cancer, and there is considerable interest in whether cancer stem cell markers or biologic surrogates may be predictive of response to radiation therapy. We review the data or in some cases lack of data regarding stem cell correlates as predictors of radiation resistance as well as the correlation of known predictors with stem cell biology. More research is certainly needed to investigate potential predictors of radiation response, stem cell or otherwise, to move us toward the goal of personalized radiation therapy.

Targeting breast cancer stem cells in triple-negative breast cancer using a combination of LBH589 and salinomycin

The aim of this study is to investigate the efficacy of combining a histone deacetylase inhibitor (LBH589) and a breast cancer stem cells (BCSC)-targeting agent (salinomycin) as a novel combination therapy for triple-negative breast cancer (TNBC). We performed in vitro studies using the TNBC cell lines to examine the combined effect. We used the mammosphere and ALDEFLUOR assays to estimate BCSC self-renewal capacity and distribution of BCSCs, respectively. Synergistic analysis was performed using CalcuSyn software. For in vivo studies, aldehyde dehydrogenase 1 ALDH1-positive cells were injected into non-obese diabetic/severe combined immunodeficiency gamma (NSG) mice. After tumor formation, mice were treated with LBH589, salinomycin, or in combination. In a second mouse model, HCC1937 cells were first treated with each treatment and then injected into NSG mice. For mechanistic analysis, immunohistochemistry and Western blot analysis were performed using cell and tumor samples. HCC1937 cells displayed BCSC properties including self-renewal capacity, an ALDH1-positive cell population, and the ability to form tumors. Treatment of HCC1937 cells with LBH589 and salinomycin had a potent synergistic effect inhibiting TNBC cell proliferation, ALDH1-positive cells, and mammosphere growth. In xenograft mouse models treated with LBH589 and salinomycin, the drug combination effectively and synergistically inhibited tumor growth of ALDH1-positive cells. The drug combination exerted its effects by inducing apoptosis, arresting the cell cycle, and regulating epithelial-mesenchymal transition (EMT). Combination of LBH589 and salinomycin has a synergistic inhibitory effect on TNBC BCSCs by inducing apoptosis, arresting the cell cycle, and regulating EMT; with no apparent associated severe toxicity. This drug combination could therefore offer a new targeted therapeutic strategy for TNBC and warrants further clinical study in patients with TNBC.

Cancer stem cells and their implication in breast cancer

BACKGROUND

The cancer stem cell (CSC) hypothesis on the origin of cancer has recently gained considerable support. CSCs are tumour cells with the capacity for self-renewal and differentiation that direct the origin and progression of the disease and may be responsible for relapse, metastasis and treatment failures.

DESIGN

This article reviews breast CSCs (BCSCs) phenotyping, clinical implications and clinical trials focused on BCSCs in breast cancer. Relevant studies were found through PubMed and Clinicaltrials.gov databases.

RESULTS

Cancer stem cells are identified and isolated using membrane and cell activity markers; in the case of BCSCs, these are CD44(+) /CD24(low/-) and show aldehyde dehydrogenase activity, alongside their capacity to grow and form mammospheres. The presence of stem cell properties is associated with a worse outcome. Hence, these cells have important clinical implications, and elucidation of the mechanisms underlying their activity will allow the development of novel effective therapies and diagnostic instruments, improving the prognosis of these patients.

CONCLUSIONS

Standard treatments are directed against the tumour mass and do not eliminate CSCs. There is therefore a need for specific anti-CSC therapies, and numerous authors are investigating new targets to this end, as reported in this review. It is also necessary for clinical trials to be undertaken to allow this new knowledge to be applied in the clinical setting. However, there have been few trials on anti-BCSCs therapies to date.

Clinicopathologic characteristics of breast cancer stem cells identified on the basis of aldehyde dehydrogenase 1 expression

Purpose

Breast cancer displays varying molecular and clinical features. The ability to form breast tumors has been shown by several studies with aldehyde dehydrogenase 1 (ALDH1) positive cells. The aim of this study is to investigate the association between ALDH1 expression and clinicopathologic characteristics of invasive ductal carcinoma.

Methods

We investigated breast cancer tissues for the prevalence of ALDH1⁺ tumor cells and their prognostic value. The present study included paraffin-embedded tissues of 70 patients with or without recurrences. We applied immunohistochemical staining for the detection of ALDH1⁺ cells. Analysis of the association of clinical outcomes and molecular subtype with marker status was conducted.

Results

ALDH1⁺ and ALDH1^- tumors were more frequent in triple-negative breast cancers and in luminal A breast cancers, respectively (p<0.01). ALDH1 expression was found to exert significant impact on disease free survival (DFS) (ALDH1⁺ vs. ALDH1^-, 53.1±6.7 months vs. 79.2±4.7 months; p=0.03) and overall survival (OS) (ALDH1⁺ vs. ALDH1^-, 68.5±4.7 months vs. 95.3±1.1 months; p<0.01). In triple-negative breast cancer (TNBC) patients, DFS and OS showed no statistical differences according to ALDH1 expression (ALDH1⁺ vs. ALDH1^-, 45.3±9.4 months vs. 81.3±7.4 months, p=0.52; 69.0±7.5 months vs. 91.3±6.3 months, p=0.67). However, non-TNBC patients showed significant OS difference between ALDH1⁺ and ALDH1^- tumors (ALDH1⁺ vs. ALDH1^-, 77.6±3.6 months vs. 98.0±1.0 months; p=0.04) with no statistical difference of DFS (ALDH1⁺ vs. ALDH1^-, 60.5±8.0 months vs. 81.8±4.6 months; p=0.27).

Conclusion

Our findings suggest that the expression of ALDH1 in breast cancer may be associated with TNBC and poor clinical outcomes. On the basis of our findings, we propose that ALDH1 expression in breast cancer could be correlated with poor prognosis, and may contribute to a more aggressive cancer phenotype.

Expression status of let-7a and miR-335 among breast tumors in patients with and without germ-line BRCA mutations

The genetic factors of cancer predisposition remain elusive in the majority of familial and/or early-onset cases of breast cancer (BC). This type of BC is promoted by germ-line mutations that inactivate BRCA1 or BRCA2. On the other hand, recent studies have indicated that alterations in the levels of miRNA expression are linked to this disease. Although BRCA1 and BRCA2 gene mutations have been reported to commonly lead to alterations in genes that encode cancer-related proteins, little is known regarding the putative impact of these mutations on noncoding miRNAs. In the present study, we aimed to determine whether miRNA dysregulation is involved in the pathogenesis of BRCA-mutated BC. An expression analysis of 14 human miRNAs previously shown to be related to BC diagnosis, prognosis, and drug resistance was conducted using tissues from 60 familial and/or early-onset patients whose peripheral blood samples had been screened for BRCA1 and BRCA2 mutations through sequence analysis. Let-7a and miR-335 expression levels were significantly downregulated in the tumors of patients with a BRCA mutation compared with those of patients without a BRCA mutation (P = 0.04 and P = 0.02, respectively). Our results defined the associations between the expression status of let-7a and miR-335 and BRCA mutations. The expression analysis of these miRNAs might be used as biomarkers of the BRCA mutation status of early-onset and/or familial BC.

CD44 is prognostic for overall survival in the NCI randomized trial on breast conservation with 25 year follow-up

CD44 is a transmembrane glycoprotein involved in numerous cellular functions, including cell adhesion and extracellular matrix interactions. It is known to be functionally diverse, with alternative splice variants increasingly implicated as a marker for tumor-initiating stem cells associated with poor prognosis. Here, we evaluate CD44 as a potential marker of long-term breast cancer outcomes. Tissue specimens from patients treated on the National Cancer Institute 79-C-0111 randomized trial of breast conservation versus mastectomy between 1979 and 1987 were collected, and immunohistochemistry was performed using the standard isoform of CD44. Specimens were correlated with patient characteristics and outcomes. Survival analysis was performed using the log rank test. Fifty-one patients had evaluable tumor sections and available long-term clinical follow up data at a median follow up of 25.7 years. Significant predictors of OS were tumor size (median OFS 25.4 years for ≤2 cm vs. 7.5 years for >2 cm, p = 0.001), nodal status (median OS 17.2 years for node-negative patients vs. 6.7 years for node positive patients, p = 0.017), and CD44 expression (median OS 18.9 years for CD44 positive patients vs. 8.6 years for CD44 negative patients, p = 0.049). There was a trend toward increased PFS for patients with CD44 positive tumors (median PFS 17.9 vs. 4.3 years, p = 0.17), but this did not reach statistical significance. These findings illustrate the potential utility of CD44 as a prognostic marker for early stage breast cancer. Subgroup analysis in patients with lymph node involvement revealed CD44 positivity to be most strongly associated with increased survival, suggesting a potential role of CD44 in decision making for axillary management. As there is increasing interest in CD44 as a therapeutic target in ongoing clinical trials, the results of this study suggest additional investigation regarding the role CD44 in breast cancer is warranted.