ALDH1 expression is enriched in breast cancers arising in young women but does not predict outcome

Effects of a humanized CD47 antibody and recombinant SIRPα proteins on triple negative breast carcinoma stem cells

Signal regulatory protein-α (SIRPα, SHPS-1, CD172a) expressed on myeloid cells transmits inhibitory signals when it engages its counter-receptor CD47 on an adjacent cell. Elevated CD47 expression on some cancer cells thereby serves as an innate immune checkpoint that limits phagocytic clearance of tumor cells by macrophages and antigen presentation to T cells. Antibodies and recombinant SIRPα constructs that block the CD47-SIRPα interaction on macrophages exhibit anti-tumor activities in mouse models and are in ongoing clinical trials for treating several human cancers. Based on prior evidence that engaging SIRPα can also alter CD47 signaling in some nonmalignant cells, we compared direct effects of recombinant SIRPα-Fc and a humanized CD47 antibody that inhibits CD47-SIRPα interaction (CC-90002) on CD47 signaling in cancer stem cells derived from the MDA-MB- 231 triple-negative breast carcinoma cell line. Treatment with SIRPα-Fc significantly increased the formation of mammospheres by breast cancer stem cells as compared to CC-90002 treatment or controls. Furthermore, SIRPα-Fc treatment upregulated mRNA and protein expression of ALDH1 and altered the expression of genes involved in epithelial/mesenchymal transition pathways that are associated with a poor prognosis and enhanced metastatic activity. This indicates that SIRPα-Fc has CD47-mediated agonist activities in breast cancer stem cells affecting proliferation and metastasis pathways that differ from those of CC-90002. This SIRPα-induced CD47 signaling in breast carcinoma cells may limit the efficacy of SIRPα decoy therapeutics intended to stimulate innate antitumor immune responses.

Secretory phospholipase sPLA2-IIAloss impairs tumorigenic and metastatic potential in breast cancer cells

Breast cancer stem cells (BCSCs) are slow cycling cells that escape the traditional chemo-radio-therapy, thereby contributing in resistance and recurrence. Although several markers have been identified, it is still challenging to develop strategies targeting them. In this study, we have isolated BCSCs from MCF-7 cell line using markers CD44+/CD24-/low, which showed higher percentage of mammospheres in CSC population. Moreover, in vivo tumorigenic potential of BCSCs showed as low as 10,000 cells had the ability to develop tumors when transplanted into NOD-SCID mice. We observed an increased level of EMT markers in CSC population. Overexpression of secretory phospholipase sPLA2-IIA was found in CSCs. Further, we have uncovered the upregulation of sPLA2-IIA mediated through JNK signaling in breast cancer cells whereas knockdown of sPLA2-IIA reduces JNK signaling, cell proliferation, EMT and in vivo tumorigenic potential in breast cancer cells. Our study reveals overexpression of sPLA2-IIA in two different breast cancer cells such as MCF7 (ER+,PR+) and a triple negative, MDA-MB-231 (ER-PR-HER2-). Further, the novel role of sPLA2-IIA was discerned by unraveling the molecular mechanism, which regulates the cell proliferation and metastasis in breast cancer cells.

Pathogenesis and Potential Therapeutic Targets for Triple-Negative Breast Cancer

Triple negative breast cancer (TNBC) is a heterogeneous tumor characterized by early recurrence, high invasion, and poor prognosis. Currently, its treatment includes chemotherapy, which shows a suboptimal efficacy. However, with the increasing studies on TNBC subtypes and tumor molecular biology, great progress has been made in targeted therapy for TNBC. The new developments in the treatment of breast cancer include targeted therapy, which has the advantages of accurate positioning, high efficiency, and low toxicity, as compared to surgery, radiotherapy, and chemotherapy. Given its importance as cancer treatment, we review the latest research on the subtypes of TNBC and relevant targeted therapies.

Cancer Stem Cells-Origins and Biomarkers: Perspectives for Targeted Personalized Therapies

The use of biomarkers in diagnosis, therapy and prognosis has gained increasing interest over the last decades. In particular, the analysis of biomarkers in cancer patients within the pre- and post-therapeutic period is required to identify several types of cells, which carry a risk for a disease progression and subsequent post-therapeutic relapse. Cancer stem cells (CSCs) are a subpopulation of tumor cells that can drive tumor initiation and can cause relapses. At the time point of tumor initiation, CSCs originate from either differentiated cells or adult tissue resident stem cells. Due to their importance, several biomarkers that characterize CSCs have been identified and correlated to diagnosis, therapy and prognosis. However, CSCs have been shown to display a high plasticity, which changes their phenotypic and functional appearance. Such changes are induced by chemo- and radiotherapeutics as well as senescent tumor cells, which cause alterations in the tumor microenvironment. Induction of senescence causes tumor shrinkage by modulating an anti-tumorigenic environment in which tumor cells undergo growth arrest and immune cells are attracted. Besides these positive effects after therapy, senescence can also have negative effects displayed post-therapeutically. These unfavorable effects can directly promote cancer stemness by increasing CSC plasticity phenotypes, by activating stemness pathways in non-CSCs, as well as by promoting senescence escape and subsequent activation of stemness pathways. At the end, all these effects can lead to tumor relapse and metastasis. This review provides an overview of the most frequently used CSC markers and their implementation as biomarkers by focussing on deadliest solid (lung, stomach, liver, breast and colorectal cancers) and hematological (acute myeloid leukemia, chronic myeloid leukemia) cancers. Furthermore, it gives examples on how the CSC markers might be influenced by therapeutics, such as chemo- and radiotherapy, and the tumor microenvironment. It points out, that it is crucial to identify and monitor residual CSCs, senescent tumor cells, and the pro-tumorigenic senescence-associated secretory phenotype in a therapy follow-up using specific biomarkers. As a future perspective, a targeted immune-mediated strategy using chimeric antigen receptor based approaches for the removal of remaining chemotherapy-resistant cells as well as CSCs in a personalized therapeutic approach are discussed.

Tumorigenic and Metastatic Role of CD44-/low/CD24-/low Cells in Luminal Breast Cancer

Cells with high CD44 but low CD24 expression (CD44^high/CD24^-/low) and high aldehyde dehydrogenase activity (ALDH^br) are widely considered to be drivers of metastasis, therapy resistance and tumor recurrence in breast cancer. However, the role of the CD44^high/CD24^-/low and ALDH^br phenotypes in identifying tumorigenic cells in breast cancer remains controversial due to the discrepancy in their distribution and tumorigenic potential in intrinsic breast cancer subtypes. In this study, we analyzed the cells expressing these markers in six different breast cancer cell lines representing major breast cancer subtypes (T47D, MCF-7, BT-474, AU-565, Hs578T and MDA-MB-231). CD44^high/CD24^-/low, ALDH^br and CD44^-/low/CD24^-/low cell populations were isolated by flow cytometry and analyzed for hallmark stem cell characteristics of differentiation, migration, invasiveness and metastasis using in vitro and in vivo techniques. Our results demonstrate that the CD44^-/low/CD24^-/low cell population, which is enriched in luminal cell lines (T47D, MCF-7 and BT-474), possesses metastatic and tumorigenic properties. We also show that, contrary to previous claims, the expression of the ALDH1 isoform ALDH1A1 does not affect the tumorigenic potential of cell lines with high ALDH activity (BT-474 and AU-565). Further transcriptomic and clinical studies are needed to determine the potential of these markers as early diagnostic tools and treatment targets.

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.

Phenotypic and microRNA characterization of the neglected CD24+ cell population in MCF-7 breast cancer 3-dimensional spheroid culture

BACKGROUND

In vitro 3-dimensional (3D) spheroid culture has been widely used as model to enrich CD44CD24 cancer stem cells (CSC) with high aldehyde dehydrogenase 1 (ALDH1) activity. Although CD24 subpopulation was known to be present in 3D spheroids and may influence cancer drug therapies, its characteristics and CSC properties were not well defined.

METHODS

In this study, CD24 population from the Michigan Cancer Foundation-7 (MCF-7) spheroid was sorted and subjected to spheroid formation test, stem cell markers immunofluorescence, invasion and migration test, as well as microRNA expression profiling.

RESULTS

Sorted MCF-7 CD24 cells from primary spheroids were able to reform its 3D spheroid shape after 7 days in nonadherent culture conditions. In contrast to the primary spheroids, the expression of SOX-2, CD44, CD49f, and Nanog was dim in MCF-7 CD24 cells. Remarkably, MCF-7 CD24 cells were found to show high expression of ALDH1 protein which may have resulted in these cells exhibiting higher resistance against doxorubicin and cisplatin when compared with that of the parental cells. Moreover, microRNA profiling has shown that the absence of CSC properties was consistent with the downregulation of major CSCs-related pathways including Hedgehog, wingless-related integration site (Wnt), and microtubule associated protein kinase (MAPK) signaling pathways. However, the upregulated pathways such as adherens junctions, focal adhesion, and tight junction suggest that CD24 cells were probably at an epithelial-like state of cell transition.

CONCLUSION

In conclusion, neglected CD24 cells in MCF-7 spheroid did not exhibit typical breast CSCs properties. The presence of miRNAs and their analyzed pathways suggested that these cells could be a distinct intermediate cell state in breast CSCs.

Gene Combination of CD44 rs187116, CD133 rs2240688, NF-κB1 rs28362491 and GSTM1 Deletion as a Potential Biomarker in Risk Prediction of Breast Cancer in Lower Northern Thailand

Background:

Biomarkers play an important role in oncology, including risk assessment, treatment prediction, and monitoring the progression of disease. In breast cancer, many genes are used as biomarkers. Since, several SNP variations of hallmark – related genes have been reported to be of value in risk prediction in various cancers and populations, some genetic polymorphism loci were combined and reported as biomarkers for use in the risk assessment of breast cancer in Thai people.

Methods:

Twelve cancer gene hallmarks (15 polymorphic loci) were selected and genotyped in 184 breast cancer patients and 176 healthy individuals in Phitsanulok, Thailand.

Results:

AA genotype of CD44 rs187116 (c.67+4883G>A), the C allele of CD133 rs2240688 (c.*667A>C), the *2 allele (4 bp deletion) of NF-κB1 rs28362491 and the homozygous null allele genotype of GSTM1 were significantly associated with an increased risk of breast cancer (p<0.05). A combination of these 4 significant loci showed that AA-AA-*1*1-homozygous null allele genotype has the greatest correlation with increased risk of breast cancer (OR = 21.00; 95% CI: 1.77 to 248.11; p = 0.015), followed by GA-AA-*2*2- homozygous null allele genotype (p = 0.037) and GG-AC-*1*2- homozygous null allele genotype (p = 0.028).

Conclusion:

These findings suggest that the polymorphisms of CD44 rs187116 (c.67+4883G>A), CD133 rs2240688 (c.*667A>C), NF-κB1 rs28362491 and GSTM1 homozygous null allele genotype might be associated with an increased risk of breast cancer, and this gene combination could possibly be used as biomarkers for risk prediction, which would be of benefit in planning health surveillance and cancer prevention.

Citral induced apoptosis in MDA-MB-231 spheroid cells

Background

Breast cancer remains a leading cause of death in women worldwide. Although breast cancer therapies have greatly advanced in recent years, many patients still develop tumour recurrence and metastasis, and eventually succumb to the disease due to chemoresistance. Citral has been reported to show cytotoxic effect on various cancer cell lines. However, the potential of citral to specifically target the drug resistant breast cancer cells has not yet been tested, which was the focus of our current study.

Methods

The cytotoxic activity of citral was first tested on MDA-MB-231 cells in vitro by MTT assay. Subsequently, spheroids of MDA-MB-231 breast cancer cells were developed and treated with citral at different concentrations. Doxorubicin, cisplatin and tamoxifen were used as positive controls to evaluate the drug resistance phenotype of MDA-MB-231 spheroids. In addition, apoptosis study was performed using AnnexinV/7AAD flowcytometry. Aldefluor assay was also carried out to examine whether citral could inhibit the ALDH-positive population, while the potential mechanism of the effect of citral was carried out by using quantitative real time- PCR followed by western blotting analysis.

Results

Citral was able to inhibit the growth of the MDA-MB-231 spheroids when compared to a monolayer culture of MDA-MB-231 cells at a lower IC₅₀ value. To confirm the inhibition of spheroid self-renewal capacity, the primary spheroids were then cultured to additional passages in the absence of citral. A significant reduction in the number of secondary spheroids were formed, suggesting the reduction of self-renewal capacity of these aldehyde dehydrogenase positive (ALDH⁺) drug resistant spheroids. Moreover, the AnnexinV/7AAD results demonstrated that citral induced both early and late apoptotic changes in a dose-dependent manner compared to the vehicle control. Furthermore, citral treated spheroids showed lower cell renewal capacity compared to the vehicle control spheroids in the mammosphere formation assay. Gene expression studies using quantitative real time PCR and Western blotting assays showed that citral was able to suppress the self-renewal capacity of spheroids and downregulate the Wnt/β-catenin pathway.

Conclusion

The results suggest that citral could be a potential new agent which can eliminate drug-resistant breast cancer cells in a spheroid model via inducing apoptosis.

Stromal CD10 expression in breast cancer correlates with tumor invasion and cancer stem cell phenotype

Background

Previous investigations have indicated that CD10 is associated with biological aggressivity in human cancers, but the use of this marker for diagnosis and prognosis is more complex. The aim of this study was to evaluate the expression of CD10 in breast cancer and its association with the clinicopathological features. In addition, we investigated whether a relationship exists between CD10 expression and cancer stem cells.

Methods

CD10 expression was examined by the immunohistochemistry in a series of 133 invasive breast carcinoma cases. Results were correlated to several clinicopathological parameters. Cancer stem cell phenotype was assessed by the immunohistochemical analysis of CD44 and ALDH1.

Results

Significant CD10 expression was found in the fusiform stromal cells in 19.5% of the cases and in the neoplastic cells in 7% of the cases. The stromal CD10 positivity was more frequently found in tumors with lymph node metastasis (p = 0.01) and a high histological grade (p = 0.01). However, CD10 expression by the neoplastic cells correlates with a high histological grade (p = 0.03) and the absence of estrogen (p = 0.002) as well as progesterone (p = 0.001) receptor expression.

We also found that CD10 expression by the stromal cells, but not by the neoplastic cells, correlates significantly with the expression of cancer stem cell markers (CD44+/ALDH1+) (p = 0.002).

Conclusion

These findings support the role of the stromal CD10 expression in breast cancer progression and dissemination, and suggest a relationship with cancer stem cells.

ALDH1A1 mRNA expression in association with prognosis of triple-negative breast cancer

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

Aldehyde dehydrogenase as a marker and functional mediator of metastasis in solid tumors

There is accumulating evidence indicating that aldehyde dehydrogenase (ALDH) activity selects for cancer cells with increased aggressiveness, capacity for sustained proliferation, and plasticity in primary tumors. However, emerging data also suggests an important mechanistic role for the ALDH family of isoenzymes in the metastatic activity of tumor cells. Recent studies indicate that ALDH correlates with either increased or decreased metastatic capacity in a cellular context-dependent manner. Importantly, it appears that different ALDH isoforms support increased metastatic capacity in different tumor types. This review assesses the potential of ALDH as biological marker and mechanistic mediator of metastasis in solid tumors. In many malignancies, most notably in breast cancer, ALDH activity and expression appears to be a promising marker and potential therapeutic target for treating metastasis in the clinical setting.

Tumor Heterogeneity in Breast Cancer

Tumor heterogeneity is the topic de jour, partly because molecular biologists and researchers are identifying it using sophisticated gene/DNA analysis techniques. Clinicians and pathologists are well acquainted with marked variability in clinical presentations, tumor histology, and, more importantly, clinical outcomes of their patients. In this review, we address these issues head-on and document that tumor heterogeneity is an old friend (or, more correctly, a foe). We described heterogeneity that exists at all levels—clinical, histologic, and molecular—and briefly outline the strategies that have been used by clinicians and pathologists to tackle this complicated issue.

Clinicopathological significance of ALDH1A1 in lung, colorectal, and breast cancers: a meta-analysis

AIM

Aldehyde dehydrogenase 1 family member A1 (ALDH1A1) is a putative cancer stem cell marker. This meta-analysis evaluated ALDH1A1 expression's clinicopathological associations with lung cancer (LC), colorectal cancer (CRC) and breast cancer (BC).

MATERIALS & METHODS

Publications were retrieved from various databases and assessed for relevance and quality. Relationships between ALDH1A1 expression and clinicopathological characteristics were evaluated using Review Manager 5.2 software.

RESULTS

Thirty-eight studies were included (6057 patients). ALDH1A1 expression was significantly associated with the presence of LC; lymph node metastasis, clinical stage and differentiation in LC and BC; and molecular subtype in BC (p < 0.05). There were no significant association with BC tumor size and CRC.

CONCLUSION

ALDH1A1 may be a stem cell marker in LC and BC.

Stem cell biomarker ALDH1A1 in breast cancer shows an association with prognosis and clinicopathological variables that is highly cut-off dependent

AIMS

Aldehyde dehydrogenase family 1 member A1 (ALDH1A1) is a putative marker of breast cancer stem cells (CSCs) with prognostic implications when expressed in cancer or stroma. However, previous results are contradictory and we therefore aimed to further evaluate the impact of ALDH1A1 on distant disease-free survival (DDFS) and correlation with clinicopathological variables in breast cancer, specifically by evaluating different cut-offs.

METHODS

Two breast cancer cohorts (N=216 and N=210) were evaluated with immunohistochemistry for ALDH1A1 on tissue microarrays with three different cut-offs in cancer cells and in stromal cells. The association of ALDH1A1 with DDFS and other clinicopathological variables was assessed. As further validation, gene expression levels of ALDH1A1 and association with survival were analysed in one of the cohorts and a separate cohort.

RESULTS

ALDH1A1 expression in cancer cells was associated with either a better or a worse prognosis, depending on cut-off. Considering weakly stained cancer cells as positive, ALDH1A1+ was associated with a better prognosis in both cohorts. Considering only strongly stained cells as positive, ALDH1A1+ was associated with oestrogen receptor and progesterone receptor negativity in both cohorts and worse prognosis in one of the cohorts. Stromal ALDH1A1 staining was associated with improved DDFS in one cohort. Gene expression analysis showed that a high ALDH1A1 expression was associated with a better prognosis.

CONCLUSIONS

ALDH1A1 is associated with DDFS and clinicopathological variables, both in cancer cells and stroma, but is highly cut-off dependent. Only the strongly ALDH1A1-stained cells show a more aggressive phenotype typical for CSCs.

Aldehyde dehydrogenase 1 expression correlates with clinicopathologic features of patients with breast cancer: a meta-analysis

A number of studies have investigated the relationship between aldehyde dehydrogenase 1 (ALDH1) expression and the clinical pathological features of the patients with breast cancer. However, conclusions reported by different parties seem to be inconsistent. We have reviewed published studies and carried out this meta-analysis to provide credible results. We searched PubMed for articles published in English until September 12, 2014. Our main analyses were focused on the association between ALDH1 and the clinical pathological features, such as age, tumor size, nodal status, lymphovascular invasion, histological grade, and the expression of ER, PR, and HER2 by meta-analysis methods. If heterogeneity was observed, we used random effects model to calculate the overall odds ratios, otherwise fixed effects model was used. Twenty-one eligible studies were included in the present meta-analysis. From the pooled analyses, there was significant association between ALDH1 expression and histological grade (low vs. intermediate: pooled OR = 1.51, 95% CI: 1.09-2.10, P = 0.01; intermediate vs. high: pooled OR = 1.86, 95% CI: 1.12-3.07, P = 0.02), ER expression (pooled OR = 0.41, 95% CI: 0.29-0.58, P < 0.00001), and PR expression (pooled OR = 0.56, 95% CI: 0.40-0.77, P = 0.0004). No clear correlation was found between ALDH1 expression and age, tumor size, lymph node (LN) metastasis, lynphovascular invasion, and HER2 expression (P > 0.05). Despite the inconsistency in the published reports, this meta-analysis provides credible evidence to support the association between ALDH1 and breast cancer. However, it is necessary to conduct large sample studies using standardized and well-matched controls.

Cancer stem cell and epithelial-mesenchymal transition markers predict worse outcome in metaplastic carcinoma of the breast

Metaplastic breast carcinomas are known to overexpress markers of epithelial-mesenchymal transition and cancer stem cells. We evaluated their immunohistochemical expression, correlating with clinicopathological parameters and survival outcomes. The study cohort comprised 63 cases diagnosed at the Department of Pathology, Singapore General Hospital. Tumor size, grade, lymph node stage, and metaplastic components were reviewed. Immunohistochemistry was performed on sections cut from tissue microarray blocks. Antibodies to ER, PR, HER2, CK14, EGFR, 34βE12, cancer stem cell markers (CD44, CD24, ALDH1A1), epithelial-mesenchymal transition markers (Twist and E-cadherin), were applied. Survival outcomes were correlated with immunohistochemical findings. T2 tumors accounted for 74.7 % of cases, with grade 3 tumors predominating (71.4 %). Triple negativity occurred in 87.3 %, and basal-like subtype in 69.8 % of tumors. CD44+, CD44+CD24-, ALDH1A1+, loss of membranous E-cadherin (Ecadloss) and positive Twist expression was found in 82.5, 73.0, 77.8, 54.0, and 57.1 % of tumors, respectively. Combinational phenotypes of CD44+EcadlossTwist+, CD44+CD24-EcadlossTwist+, and ALDH1A1+EcadlossTwist+ were observed in 28.6, 25.4, and 2.6 % of tumors. Histologic grade was significantly correlated with E-cadherin loss (p = 0.042), Twist positivity (P = 0.001), CD44+EcadlossTwist+ (P = 0.010), CD44+CD24-EcadlossTwist+ (P = 0.018), and ALDH1A1+EcadlossTwist+(P = 0.010). Lymph node stage was significantly associated with CD44+EcadlossTwist+(P = 0.044) and CD44+CD24-EcadlossTwist+ (P = 0.044). Basal-like phenotype was significantly correlated with CD44 expressing (P = 0.004) and CD44+CD24- tumors (P = 0.049). Tumors harboring CD44+EcadlossTwist+ and CD44+CD24-EcadlossTwist+ phenotypes disclosed early recurrence (P = 0.027, P = 0.006) and poorer overall survival (P = 0.037, P = 0.006), respectively. Expression of cancer stem cell and epithelial-mesenchymal transition markers in metaplastic breast cancers correlates with adverse pathological parameters and outcome.

Targeting breast cancer initiating cells: advances in breast cancer research and therapy

Over the past 10 years there have been significant advances in our understanding of breast cancer and the important roles that breast cancer initiating cells (CICs) play in the development and resistance of breast cancer. Breast CICs endowed with self-renewing and tumor-initiating capacities are believed to be responsible for the relapses which often occur after various breast cancer therapies. In this review, we will summarize some of the key developments in breast CICs which will include discussion of some of the key genes implicated: estrogen receptor (ER), HER2, BRCA1, TP53, PIK3CA, RB, P16INK1 and various miRs as well some drugs which are showing promise in targeting CICs. In addition, the concept of combined therapies will be discussed. Basic and clinical research is resulting in novel approaches to improve breast cancer therapy by targeting the breast CICs.

ALDH1A1 expression correlates with clinicopathologic features and poor prognosis of breast cancer patients: a systematic review and meta-analysis

BACKGROUND

Aldehyde dehydrogenase 1 family member A1 (ALDH1A1) has been identified as a putative cancer stem cell (CSC) marker in breast cancer. However, the clinicopathological and prognostic significance of this protein in breast cancer patients remains controversial.

METHODS

This meta-analysis was conducted to address the above issues using 15 publications covering 921 ALDH1A1(+) cases and 2353 controls. The overall and subcategory analyses were performed to detect the association between ALDH1A1 expression and clinicopathological/prognostic parameters in breast cancer patients.

RESULTS

The overall analysis showed that higher expression of ALDH1A1 is associated with larger tumor size, higher histological grade, greater possibility of lymph node metastasis (LNM), higher level expression of epidermal growth factor receptor 2 (HER2), and lower level expression of estrogen receptor (ER)/progesterone receptor (PR). The prognosis of breast cancer patients with ALDH1A1(+) tumors was poorer than that of the ALDH1A1(-) patients. Although the relationships between ALDH1A1 expression and some clinicopathological parameters (tumor size, LNM, and the expression of HER2) was not definitive to some degree when we performed a subcategory analysis, the predictive values of ALDH1A1 expression for histological grade and survival of breast cancer patients were significant regardless of the different cutoff values of ALDH1A1 expression, the different districts where the patients were located, the different clinical stages of the patients, the difference in antibodies used in the studies, and the surgery status.

CONCLUSIONS

Our results indicate that ALDH1A1 is a biomarker to predict tumor progression and poor survival of breast cancer patients. This marker should be taken into consideration in the development of new diagnostic and therapeutic program for breast cancer.

Lack of correlation of stem cell markers in breast cancer stem cells

Background:

Various markers are used to identify the unique sub-population of breast cancer cells with stem cell properties. Whether these markers are expressed in all breast cancers, identify the same population of cells, or equate to therapeutic response is controversial.

Methods:

We investigated the expression of multiple cancer stem cell markers in human breast cancer samples and cell lines in vitro and in vivo, comparing across and within samples and relating expression with growth and therapeutic response to doxorubicin, docetaxol and radiotherapy.

Results:

CD24, CD44, ALDH and SOX2 expression, the ability to form mammospheres and side-population cells are variably present in human cancers and cell lines. Each marker identifies a unique rather than common population of cancer cells. In vivo, cells expressing these markers are not specifically localized to the presumptive stem cell niche at the tumour/stroma interface. Repeated therapy does not consistently enrich cells expressing these markers, although ER-negative cells accumulate.

Conclusions:

Commonly employed methods identify different cancer cell sub-populations with no consistent therapeutic implications, rather than a single population of cells. The relationships of breast cancer stem cells to clinical parameters will require identification of specific markers or panels for the individual cancer.

Genomic profiling in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is defined by a lack of hormone receptor expression as well as lack of overexpression/amplification of HER2/neu. Patients with TNBC show a significantly worse prognosis compared to patients with other breast cancer subtypes. TNBC, however, is a heterogeneous entity both with regard to clinical/pathological characteristics and molecular biology. This review summarizes the current data on TNBC with a particular focus on mutational and gene expression profiling and the association between TNBC and breast cancer stem cells.