Expression of EGFR and c-kit is associated with the basal-like phenotype in breast carcinomas of African women

Network pharmacology-based strategy for predicting therapy targets of Ecliptae Herba on breast cancer

Breast cancer is a prevalent malignancy affecting women globally, characterized by significant morbidity and mortality rates. Ecliptae Herba is a traditional herbal medicine commonly used in clinical practice, has recently been found to possess antitumor properties. In order to explore the underlying material basis and molecular mechanisms responsible for the anti-breast cancer effects of Ecliptae Herba, we used network pharmacology and experimental verification. UPLC-MS/MS was utilized to identify compounds present in Ecliptae Herba. The active components of Ecliptae Herba and its breast cancer targets were screened using public databases. Hub genes were identified using the STRING and Metascape database. The R software was utilized for visual analysis of GO and KEGG pathways. The affinity of the hub targets for the active ingredients was assessed by molecular docking analysis, which was verified by experimental assessment. A total of 178 targets were obtained from the 10 active components of Ecliptae Herba, while 3431 targets associated with breast cancer were screened. There were 144 intersecting targets between the components and the disease. Targets with a higher degree, namely EGFR and TGFB1, were identified through the hub subnetwork of PPI. GO and KEGG analyses revealed that Ecliptae Herba plays an important role in multiple cancer therapeutic mechanisms. Moreover, molecular docking results showed that the core components had good binding affinity with key targets. Finally, it was confirmed that TGF-β1 might be a potential crucial target of Ecliptae Herba in the treatment of breast cancer by cytological experiments, and the TGF-β1/Smad signaling pathway might be an important pathway for Ecliptae Herba to exert its therapeutic effects. This study elucidated the active ingredients, key targets, and molecular mechanisms of Ecliptae Herba in the treatment of breast cancer, providing a scientific foundation and therapeutic mechanism for the prevention and treatment of breast cancer with Traditional Chinese medicine.

Receptor tyrosine kinase inhibitors in cancer

Targeted therapy is a new cancer treatment approach, involving drugs that particularly target specific proteins in cancer cells, such as receptor tyrosine kinases (RTKs) which are involved in promoting growth and proliferation, Therefore inhibiting these proteins could impede cancer progression. An understanding of RTKs and the relevant signaling cascades, has enabled the development of many targeted drug therapies employing RTK inhibitors (RTKIs) some of which have entered clinical application. Here we discuss RTK structures, activation mechanisms and functions. Moreover, we cover the potential effects of combination drug therapy (including chemotherapy or immunotherapy agents with one RTKI or multiple RTKIs) especially for drug resistant cancers.

Receptor-Defined Breast Cancer in Five East African Countries and Its Implications for Treatment: Systematic Review and Meta-Analysis

PURPOSE

Estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) are determinants of treatment and mortality for patients with breast cancer (BC). In East Africa, the estimated 5-year survival (37.7%) is far lower than the US average (90%). This meta-analysis investigates BC receptor subtypes within five East African countries to ascertain cross-country patterns and prioritize treatment needs.

METHODS

From a PubMed search, January 1, 1998-June 30, 2019, for all English-only BC articles for Ethiopia, Kenya, Rwanda, Tanzania, and Uganda, eligible studies had receptor distributions for female BC samples ≥ 30 patients. Outcomes were proportions of ER+, PR+, and HER2-positive (HER2+), and/or molecular subtypes. Data included study characteristics and mean or median patient age. Using metaprop, Stata 16, we estimated pooled proportions (ES) with 95% CIs and assessed heterogeneity.

RESULTS

Among 36 BC studies with receptor data, 21 met criteria. Weighted mean age was 47.5 years and median, 48. Overall ES were as follows: 55% for ER-positive (ER+) (95% CI, 47 to 62), 23% for HER2+ (95% CI, 20 to 26), and 27% for triple-negative BC (TNBC) (95% CI, 23 to 32).

CONCLUSION

We found differences between countries, for example, lower distribution of TNBC in Ethiopia (21%) compared with Uganda (35%). ER+, the dominant BC subtype overall at 55%, emphasizes the need to prioritize endocrine therapy. Overall proportions of HER2+ BC (with or without ER+ or PR+), 23%, approached proportions of TNBC, 27%, yet HER2 testing and treatment were infrequent. Testing and reporting of receptor subtypes would promote delivery of more effective treatment reducing the mortality disparity.

Expression and clinical significance of MAPK and EGFR in triple-negative breast cancer

To investigate the expression and clinical significance of mitogen-activated protein kinase (MAPK) and epidermal growth factor receptor (EGFR) in triple-negative breast cancer (TNBC), a total of 300 TNBC and 120 paired paracancerous tissues were examined. Immunohistochemistry was conducted to determine the expression levels of MAPK and EGFR, and the correlation between MAPK and EGFR expression was evaluated using Cramer's V test. The association between MAPK and EGFR expression, and various clinicopathological variables (such as lymph node metastasis, clinical stage, recurrence and metastasis) was also evaluated, using the χ2 test. MAPK and EGFR expression levels in TNBC tissues were significantly higher than in the paired paracancerous tissues. Moreover, MAPK expression was associated with that of EGFR in TNBC tissues. The positive expression rates of MAPK and EGFR in patients with lymph node metastasis, advanced clinical stage, tumor recurrence and metastasis were higher than those without. Patients with positive expression of MAPK and EGFR in TNBC tissues had poorer prognoses and lower overall survival times than those without expression. In summary, the expression of MAPK and EGFR is closely associated with tumor invasion and the metastasis of TNBC, and may therefore be used as an indicator of poor prognosis in patients with TNBC.

C-Kit receptor and tryptase expressing mast cells correlate with angiogenesis in breast cancer patients

C-Kit protein is a transmembrane tyrosine kinase (TK) receptor (c-KitR-TK), which is predominantly expressed on mast cells (MCs) playing a role in tumor angiogenesis. It could be also expressed on epithelial breast cancer cells (EBCCs), but no data have been published regarding the correlation between mast cells positive to c-KitR (MCs-c-KitR), EBCCs positive to c-KitR (EBCCs-c-KitR), BC angiogenesis in terms of microvessel density (MVD) and the main clinic-pathological features. This study aims to evaluate the above parameters and their correlations in a series of selected 121 female early BC patients. It has been found a strong correlation between MVD and MCDPT, and MCs-c-KitR, MVD and MCs density positive to tryptase (MCDPT), and MCs-c-KitR and MCDPT by Pearson correlation. These data suggest an involvement of both MCDPT and MCs-c-KitR in BC tumor angiogenesis. Furthermore, BC tissue expressing c-KitR could be a putative predictive factor to c-KitR-TK inhibitors. In this way, selected patients with higher MCs-c-KitR could be candidate to receive c-KitR-TK inhibitors (e.g. masitinib, sunitinib) or tryptase inhibitors (e.g. nafamostat mesilate, gabexate mesilate).

Undifferentiated Carcinoma of the Endometrium: An Expanded Immunohistochemical Analysis Including PAX-8 and Basal-Like Carcinoma Surrogate Markers

Undifferentiated carcinoma of the endometrium (UCAe) is an aggressive, underrecognized high-grade carcinoma that can occur either in pure form or in conjunction with low-grade endometrioid adenocarcinoma (i.e. dedifferentiated carcinoma). The typical solid growth pattern of UCAe can create a diagnostic dilemma as it is frequently misinterpreted as the solid component of an endometrial carcinoma or as a sarcoma. In addition, the high nuclear:cytoplasmic ratio, high mitotic index, and geographic necrosis are reminiscent of basal-like carcinoma of breast (BLCB). This study was undertaken to determine the role of a selected group of immunomarkers in the distinction of UCAe from other endometrial carcinomas, and assess the expression of DNA mismatch repair proteins, and surrogate BLCB immunomarkers in this type of tumor. Cases of UCAe were stained with antibodies against keratin cocktail, CK8/18, PAX-8, and estrogen receptor: 35 cases; progesterone receptor and Her-2/neu: 33 cases; CD44, e-cadherin, p16, and p53: 32 cases; and CK5/6, EGFR, and c-Kit: 18 cases. In addition, mismatch repair protein markers MLH1, MSH2, MSH6, and PMS2 were performed in 34 cases. We found that PAX-8 expression was lost in most cases (83%). In addition, estrogen and progesterone receptors were negative in 83% and 82% of cases, respectively. Seventy-seven percent of cases were positive for keratin cocktail and keratin 8/18, whereas only 11% of cases were positive for keratin 5/6. p16 was diffusely positive in 34% of cases, whereas p53 was expressed in >75% of the tumor cells in 31% of cases. MLH1 and PMS2 were concurrently lost in 50% of cases, whereas MSH2 and MSH6 were lost in 1 case (3%). E-cadherin and CD44 were completely lost in 50% of cases, whereas Her-2/neu was negative in all cases. EGFR was negative in 67% of cases, whereas 22% of cases showed diffuse membranous staining for this marker. UCAe is a high-grade carcinoma of Müllerian origin which tends to be negative for PAX-8. The loss of this marker appears to be a more reliable discriminator than the loss of keratin expression in the differential diagnosis with endometrioid carcinoma or serous carcinoma. UCAe tends to be diffusely positive for p53, but patchy positive for p16. Although UCAe appears to share not only some histologic features with BLCB, but also some of its immunohistochemical features (loss of estrogen receptor, progesterone receptor, and Her-2/neu, a tendency to loose e-cadherin and to express CD44), UCAe appears not to be related to BLCB because it usually lacks the expression EGFR, CK5/6, and c-Kit.

Novel therapeutic strategies in the treatment of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous subtype of breast cancer that is defined by negative estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) status. Treating patients with TNBC remains clinically challenging, as patients are not candidates for endocrine or HER2-directed therapy. As a result, chemotherapy with traditional agents such as anthracyclines and taxanes remains the only available option with moderate success. Recent discoveries have revealed that TNBC is a heterogeneous disease at the clinical, histological and molecular levels. The use of biomarkers to identify distinct subsets of TNBC that derive the greatest benefit from presently approved as well as novel therapeutics has become the main focus of current research. The aim of this review is to explore the clinical and biological complexity of TNBC as well as identify novel therapeutic options that target the various molecular subsets of TNBC.

Strong Expression of Hypoxia-Inducible Factor-1α (HIF-1α) Is Associated with Axl Expression and Features of Aggressive Tumors in African Breast Cancer

PURPOSE

Inhibition of hypoxia-inducible factor (HIF) and Axl receptor tyrosine kinase is being evaluated for targeted therapy in solid tumors. Both HIF-1α and Axl influence tumor growth and metastatic potential, and they have been linked to treatment failure in many cancers. However, there is a lack of reports on HIF-1α expression in African breast cancer, which has a poor prognosis, and novel treatment targets must therefore be established. Here, we aimed to evaluate HIF-1α in relation to Axl expression, angiogenesis markers, and other tumor characteristics in a series of African breast cancer.

METHODS

Using immunohistochemistry, we examined 261 invasive breast cancers on tissue microarrays for HIF-1α and Axl as well as several other markers, and a subset of 185 cases had information on VEGF (vascular endothelial growth factor) expression, microvessel density (MVD), proliferating microvessel density (pMVD) and vascular proliferation index (VPI) for important comparisons.

RESULTS

Strong HIF-1α expression was associated with increased Axl (p = 0.007), VEGF (p<0.0005), and p53 (p = 0.032) expression, as well as high tumor cell proliferation by Ki-67 (p = 0.006), and high tumor grade (p = 0.003). Tumors with strong HIF-1α expression had significantly higher MVD (p = 0.019) and higher pMVD (p = 0.027) than tumors with weak expression.

CONCLUSIONS

High HIF-1α expression is significantly associated with Axl and VEGF expression, and with markers of poor prognosis in this series of breast cancer, suggesting HIF-1α and Axl as potential therapeutic targets in African breast cancer.

Breast cancer survival experiences at a tertiary hospital in sub-Saharan Africa: a cohort study

BACKGROUND

Cancer of the breast is a major health burden and the most common cancer among women worldwide. Though its incidence is fourfold greater in high-income countries, in sharp contrast, mortality rates are greatest among the low-income countries. Early detection linked to appropriate treatment is the most effective strategy to improve survival. The purpose of this study therefore was to establish the survival experiences of women with breast cancer at a Ugandan hospital.

METHODS

This study is an observational analytical study. It involved 262 women during the periods 2004 to 2007 and 2010 to 2012. Kaplan Meier method and Cox regression were used to calculate breast cancer mortality and cumulative survival experiences.

RESULTS

Sixty-three out of 262 (23%) deaths were observed; mean age was 45 years, and 91 observations ended on or before follow-up. Luminal B median survival was months. The 5-year cumulative survival was 51.8 %. There were no stage I and II deaths. There were no differences in survival by phenotype adjusted for age, but there were differences for stage IV (p=0.05).

CONCLUSIONS

The cumulative 5-year survival was 51.8 %. The burden of advanced disease and associated mortality were high, and a significant number of patients were lost to follow-up after their first contact.

Molecular breast cancer subtypes prevalence in an indigenous Sub Saharan African population

Introduction

Sub-Saharan Africa is predicted to face an unprecedented growth of cancers including breast cancer. There are indications of a significant burden of aggressive and late stage breast disease among premenopausal women in sub-Saharan Africa; because hormonal status tests are not routinely done, many women are given anti-hormonal therapy empirically. There is paucity of data on breast cancer molecular subtypes and their characteristics among women in sub Saharan Africa. The objective is to determine the prevalence of breast cancer molecular phenotypes among Ugandan women.

Methods

This was a cross sectional descriptive study, conducted at a tertiary hospital in Africa. Eligible participants’ formalin fixed and paraffin embedded sections were evaluated. H & E stains and Immunochemistry (Estrogen Receptor (ER), Progesterone Receptor (PR), Human Epidermal growth factor Receptor (HER2)) were performed. Ethical approval was obtained.

Results

A total of 226 patient samples were evaluated. The mean age was 45 years (SD 14);the prevalence of Triple Negative Breast Cancer (TNBC) was 34% (77/226), Luminal A 38% (83/226), HER2 positive was 22% (49/226), and Luminal B was 5% (13/226). High-grade (III) tumors were 68%, stage III and IV constituted 75% of presentations. Histological type was mostly invasive ductal carcinoma. Most patients (55%) were from rural areas.

Conclusion

Ugandan women had an over representation of TNBC and high-grade breast tumors. Underlying reasons ought to be investigated. The empirical use of tamoxifen (anti-hormonal therapy) should be reexamined.

The relevance of the intrinsic subtype to the clinicopathological features and biomarkers in Japanese breast cancer patients

Background

Breast cancer is a disease rich in diversity, and it can be categorized into the immunohistochemical intrinsic subtypes : ER/PR + and HER2-, ER/PR + and HER2+, HER2 type, basal-like and unclassified.

Methods

In this study, in addition to the clinicopathological features potentially associated with the intrinsic subtypes, protein expression and genetic mutations of key molecules associated with breast cancer prognosis and treatment sensitivity were analyzed. The distribution of subtypes in the patient population and the differences in marker distribution across the subtypes were investigated.

Results

The immunohistochemical features of 471 consecutive surgical cases of women with primary breast cancer, treated in a single institution, were examined. There were 306 patients who were ER/PR + HER2- (65%); 41 who were ER/PR + HER2+ (8.7%); 59 with HER2 type (12.5%); 37 with basal-like (7.9%); and 28 patients whose breast cancer was unclassified (5.9%). There were no significant differences between the subtypes regarding age, menopausal status, disease stage, lymphatic invasion, blood vessel invasion and lymph node metastasis. Statistically significant differences were found for histological type and grade. Regarding protein expression and genetic mutation, significant differences were found in the distribution within each subtype for six out of 12 molecules investigated.

Conclusions

This study revealed that subtypes differ not only in their clinical pathological profiles, such as histological types and histological grades, but also in molecular expression. The molecular expression patterns observed for each intrinsic subtype may help the selection of an optimal treatment strategy.

A survey of immunohistochemical biomarkers for basal-like breast cancer against a gene expression profile gold standard

Gene expression profiling of breast cancer delineates a particularly aggressive subtype referred to as 'basal-like', which comprises ∼15% of all breast cancers, afflicts younger women and is refractory to endocrine and anti-HER2 therapies. Immunohistochemical surrogate definitions for basal-like breast cancer, such as the clinical ER/PR/HER2 triple-negative phenotype and models incorporating positive expression for CK5 (CK5/6) and/or EGFR are heavily cited. However, many additional biomarkers for basal-like breast cancer have been described in the literature. A parallel comparison of 46 proposed immunohistochemical biomarkers of basal-like breast cancer was performed against a gene expression profile gold standard on a tissue microarray containing 42 basal-like and 80 non-basal-like breast cancer cases. Ki67 and PPH3 were the most sensitive biomarkers (both 92%) positively expressed in the basal-like subtype, whereas CK14, IMP3 and NGFR were the most specific (100%). Among biomarkers surveyed, loss of INPP4B (a negative regulator of phosphatidylinositol signaling) was 61% sensitive and 99% specific with the highest odds ratio (OR) at 108, indicating the strongest association with basal-like breast cancer. Expression of nestin, a common marker of neural progenitor cells that is also associated with the triple-negative/basal-like phenotype and poor breast cancer prognosis, possessed the second highest OR at 29 among the 46 biomarkers surveyed, as well as 54% sensitivity and 96% specificity. As a positively expressed biomarker, nestin possesses technical advantages over INPP4B that make it a more ideal biomarker for identification of basal-like breast cancer. The comprehensive immunohistochemical biomarker survey presented in this study is a necessary step for determining an optimized surrogate immunopanel that best defines basal-like breast cancer in a practical and clinically accessible way.

Gene copy number variations in breast cancer of Sub-Saharan African women

The goal of this study was CGH array profiling of breast cancer from Malian women in order to define differences with those from USA. CGH array was performed in 28 samples, 17 with a triple negative phenotype. The profiles were compared to those of 106 tumors from USA. 6 chromosomal regions (6p21, 9q34, 11q13, 12q24, 17q25 and 22q12.1-22q13.1) were identified with a significant higher rate of copy number alterations. These regions contain several genes of interest including BCR. FISH and IHC confirmed that BCR was amplified and overexpressed particularly in triple negative tumors. Finally, 5 regions presented a high level of amplification in two or more samples, including 2 regions located between 9p22.3-9p23 and 9p23-9p24.1. This study confirms that breast cancers from African women present biological differences with those from USA. Larger studies are needed to go further in the identification of therapeutic targets that would be specific to African women.

Characteristics of basal cytokeratin expression in breast cancer

Breast cancer is recognised to be a heterogeneous disease and the second most common cause of morbidity and mortality worldwide in women. Basal-like breast cancer (BLBC) is associated with aggressive characteristics including development of recurrent disease and reduced survival. BLBC has been defined in some studies as tumours lacking both oestrogen receptor and progesterone receptor protein expression. Gene expression studies have shown that these tumours are also associated with expression of basal-type cytokeratins, the phenotypic patterns of basal cytokeratin expression in BLBC have not been widely studied. A well-characterised series of 995 invasive breast cancers with a long-term follow up were investigated using immunohistochemical staining for four basal cytokeratins (CK5, CK5/6, CK14 and CK17). The data were analysed using univariate and clustering analysis. As a result BLBC, as defined by negativity for ER and HER2 showed variable positivity for basal cytokeratin expression: 61.7 % CK5, 50.5 % CK5/6, 24.2 % CK14 and 23 % CK17. These characteristics were associated with poor outcome characteristics including high histological grade, mitosis, pleomorphism and tumour size >1.5 cm. CK5 positivity was more associated with ER(-), PgR(-), TN and double ER(-)PgR(-), than the other cytokeratins. Four different clusters of basal cytokeratin expression patterns were identified: (1) negativity for all basal cytokeratins, (2) CK5(+)/CK17(-), (3) CK5(-)/CK17(+) and (4) CK5(+)/CK17(+). These patterns of basal cytokeratin expression associated with differences in patient outcome, clusters 1 and 3 showed better outcomes than cluster 4 and 2, with cluster 2 having the poorest prognosis. In conclusion, four basal cytokeratin expression patterns were identified in human breast cancer using unsupervised clustering analysis and these patterns are associated with differences in patient outcome.

Immunophenotypes of glycogen rich clear cell carcinoma

PURPOSE

Glycogen rich clear cell carcinoma (GRCC) of the breast is a rare subtype of invasive ductal carcinoma and involves a poor prognosis. In the literature, less than 150 cases have been reported. Many researchers have attempted to characterize GRCC according to electron microscope, flow cytometry, or clinical data. However, an organized study of the immunophenotype of GRCC has yet to be reported.

MATERIALS AND METHODS

Here, we present three cases of GRCC and their immunohistochemical profiles.

RESULTS

Histologically, all three cases contained periodic acid stain (PAS) positive and d-PAS labile granules in their clear cytoplasm. Case I showed positivity for only estrogen receptor (ER) and c-erbB2. Case II exhibited positivity for progesterone receptor and negativity for ER and c-erbB2. Case III presented with triple negative invasive carcinoma. The expression pattern of E-cadherin was concordant with epidermal growth factor receptor and c-kit, but discordant with ki-67. Among these three cases, p53-positive cases exhibited a low proliferative index (ki-67: 15%), while p53-negative cases showed a high proliferative index (ki-67: 50-60%).

CONCLUSION

In conclusion, the immunophenotype of GRCC is not uniform, but is similar to that of conventional ductal carcinoma.

Effective targeting of triple-negative breast cancer cells by PF-4942847, a novel oral inhibitor of Hsp 90

PURPOSE

Triple-negative breast cancer (TNBC) patients have poor prognoses and survival outcomes such that the development of new targeted therapies is in strong demand. Mechanisms associated with high proliferation and aggressive tumor progression, such as PI3K/PTEN aberration, epidermal growth factor receptor (EGFR) overexpression, and cell-cycle upregulation, play important roles in TNBC. The molecular chaperone Hsp90 is required for the conformational maturation and stability of a variety of proteins in multiple pathways, such as EGFR, AKT, Raf, cdk4, etc. Therefore, an Hsp90 inhibitor may show therapeutic benefit in TNBC by targeting multiple pathways.

EXPERIMENTAL DESIGN

The novel oral Hsp90 inhibitor PF-4942847 was characterized in multiple in vitro and in vivo assays to determine its antitumor activity in TNBC cell lines. In addition, the correlation of AKT degradation and Hsp70 induction in host peripheral blood lymphocytes (PBL) and xenograft tumors was determined.

RESULTS

PF-4942847 induces degradation of multiple client proteins, cell-cycle block, apoptosis, and inhibits cell proliferation in TNBC lines, subsequently leading to tumor growth inhibition in mouse xenograft models. The correlation of AKT degradation and Hsp70 induction between PBLs and xenograft tumors reveals a differential modulation of Hsp90 activity between host and tumor tissues, and suggests that AKT degradation in PBLs may serve as a pharmacodynamic biomarker in future clinical development.

CONCLUSIONS

The novel oral Hsp90 inhibitor, PF-4942847, is a candidate for clinical development in TNBC by collaboratively targeting multiple signaling pathways. In addition, AKT degradation in PBLs may serve as a biomarker in clinical development.

Basal-like phenotype in a breast carcinoma case series from Sudan: prevalence and clinical/pathological correlations

Basal-like breast cancer, an aggressive subtype associated with high grade, poor prognosis, and younger age, is reported frequently in Africa. We analyzed the expression of the basal cytokeratins (CKs) 5/6 and 17 in a case series from Central Sudan and investigated correlations among basal CK status, ER, PgR, and Her-2/neu, and individual/clinicopathological data. Of 113 primary breast cancers 26 (23%), 38 (34%), and 46 (41%) were, respectively, positive for CK5/6, CK17, and combined basal CKs (CK5/6 and/or CK17). Combined basal CK+ status was associated with higher grade (P < .03) and inversely correlated with ER (P < .002), PgR (P = .004) and combined ER and/or PgR (P < .0002). Two clusters based on all tested markers were generated by hierarchical cluster analysis and k-mean clustering: I: designated "hormone receptors positive/luminal-like" and II: designated "hormone receptors negative", including both basal-like and Her-2/neu+ tumors. The most important factors for dataset variance were ER status, followed by PgR, CK17, and CK5/6 statuses. Overall basal CKs were expressed in a fraction of cases comparable to that reported for East and West African case series. Lack of associations with age and tumor size may represent a special feature of basal-like breast cancer in Sudan.

Characteristics of triple-negative breast cancer

Background

Triple-negative breast cancers (TNBC) neither express hormone receptors, nor overexpress HER2. They are associated with poor prognosis, as defined by low five-year survival and high recurrence rates after adjuvant therapy. Overall, TNBC share striking similarities with basal-like breast cancers (BBC), so a number of studies considered them being the same. The purpose of this review is to summarise the latest findings on TNBC concerning its relation and delineation to BBC, discuss the developmental pathways involved and address clinical implications for this complex type of breast cancer.

Methods

The recent literature from PubMed and Medline databases was reviewed.

Results

Not all TNBC are of the intrinsic BBC subtype (nonbasal (NB)-TNBC), nor are all BBC triple-negative (non-triple-negative (NTN)-BBC). There is increasing evidence that a triple-negative, basal-like breast cancer (TNBBC) subtype develops mainly through a BRCA1-related pathway. Somatic mutations that contribute to NTN-BBC and NB-TNBC development are possibly not related to this pathway, but may occur randomly due to increased genomic instability in these tumours. Several therapeutic options exist for TNBBC, which exhibited promising results in recent clinical trials. Cytotoxic therapies, e.g. combined treatment with anthracyclines or taxanes, achieved good tumour regression rates in the neo-adjuvant setting, but also showed considerable recurrence during the first 5 years after therapy. Targeted therapy options involve PARP1 and EGFR inhibition, although both approaches still need further investigation.

Conclusions

TNBC and BBC are not the same disease entity. The TNBBC subtype shows the largest homogeneity in terms of tumour development, prognosis and clinical intervention options.

Receptor tyrosine kinase signaling favors a protumorigenic state in breast cancer cells by inhibiting the adaptive immune response

Using transgenic mouse models of breast cancer that ablate Src homology and collagen A (ShcA) expression or oncogene-coupled ShcA signaling, we previously showed that this adaptor is critical for mammary tumor onset and progression. We now provide the first evidence that ShcA regulates mammary tumorigenesis, in part, through its ability to regulate the adaptive immune response. Inactivation of ShcA signaling within tumor cells results in extensive CD4(+) T-cell infiltration and induction of a humoral immune response in mammary tumors. This is associated with a robust CTL response in preneoplastic lesions that are deficient in ShcA signaling. Moreover, mammary tumor progression of ShcA-deficient hyperplasias is accelerated in a T cell-deficient background. We also uncover a clinically relevant correlation between high ShcA expression and low CTL infiltration in human breast cancers. Finally, we define a novel ShcA-regulated immune signature that functions as an independent prognostic marker of survival in human epidermal growth factor receptor 2(+) and basal breast cancers. We reveal a novel role for tumor cell-derived ShcA in the establishment and maintenance of an immunosuppressive state.

SLUG/SNAI2 and tumor necrosis factor generate breast cells with CD44+/CD24- phenotype

Background

Breast cancer cells with CD44+/CD24- cell surface marker expression profile are proposed as cancer stem cells (CSCs). Normal breast epithelial cells that are CD44+/CD24- express higher levels of stem/progenitor cell associated genes. We, amongst others, have shown that cancer cells that have undergone epithelial to mesenchymal transition (EMT) display the CD44+/CD24- phenotype. However, whether all genes that induce EMT confer the CD44+/CD24- phenotype is unknown. We hypothesized that only a subset of genes associated with EMT generates CD44+/CD24- cells.

Methods

MCF-10A breast epithelial cells, a subpopulation of which spontaneously acquire the CD44+/CD24- phenotype, were used to identify genes that are differentially expressed in CD44+/CD24- and CD44-/CD24+ cells. Ingenuity pathway analysis was performed to identify signaling networks that linked differentially expressed genes. Two EMT-associated genes elevated in CD44+/CD24- cells, SLUG and Gli-2, were overexpressed in the CD44-/CD24+ subpopulation of MCF-10A cells and MCF-7 cells, which are CD44-/CD24+. Flow cytometry and mammosphere assays were used to assess cell surface markers and stem cell-like properties, respectively.

Results

Two thousand thirty five genes were differentially expressed (p < 0.001, fold change ≥ 2) between the CD44+/CD24- and CD44-/CD24+ subpopulations of MCF-10A. Thirty-two EMT-associated genes including SLUG, Gli-2, ZEB-1, and ZEB-2 were expressed at higher levels in CD44+/CD24- cells. These EMT-associated genes participate in signaling networks comprising TGFβ, NF-κB, and human chorionic gonadotropin. Treatment with tumor necrosis factor (TNF), which induces NF-κB and represses E-cadherin, or overexpression of SLUG in CD44-/CD24+ MCF-10A cells, gave rise to a subpopulation of CD44+/CD24- cells. Overexpression of constitutively active p65 subunit of NF-κB in MCF-10A resulted in a dramatic shift to the CD44+/CD24+ phenotype. SLUG overexpression in MCF-7 cells generated CD44+/CD24+ cells with enhanced mammosphere forming ability. In contrast, Gli-2 failed to alter CD44 and CD24 expression.

Conclusions

EMT-mediated generation of CD44+/CD24- or CD44+/CD24+ cells depends on the genes that induce or are associated with EMT. Our studies reveal a role for TNF in altering the phenotype of breast CSC. Additionally, the CD44+/CD24+ phenotype, in the context of SLUG overexpression, can be associated with breast CSC "stemness" behavior based on mammosphere forming ability.

Biomarkers for Basal-like Breast Cancer

Initially recognized through microarray-based gene expression profiling, basal-like breast cancer, for which we lack effective targeted therapies, is an aggressive form of carcinoma with a predilection for younger women. With some success, immunohistochemical studies have attempted to reproduce the expression profile classification of breast cancer through identification of subtype-specific biomarkers. This review aims to present an in depth summary and analysis of the current status of basal-like breast cancer biomarker research. While a number of biomarkers show promise for future clinical application, the next logical step is a comprehensive investigation of all biomarkers against a gene expression profile gold standard for breast cancer subtype assignment.

Epidermal growth factor receptor in triple-negative and basal-like breast cancer: promising clinical target or only a marker?

Triple-negative breast cancers represent a subset of breast cancers with a particularly aggressive phenotype and poor clinical outcomes. Recent molecular profiling of these tumors has revealed a high frequency of epidermal growth factor receptor (EGFR) dysregulation, among other abnormalities. EGFR status correlates negatively with survival in patients with triple-negative breast cancers, and thus focus has turned on this receptor as a potential clinical target. Two classes of EGFR inhibitors are currently in clinical use: the monoclonal antibodies and the small molecule tyrosine kinase inhibitors. Trials of these drugs in breast cancer, however, have been largely disappointing. It remains to be seen whether advances in our understanding of the mechanisms of EGFR dysregulation and effects of multiple compensatory pathways in breast cancer, coupled with improved targeting to appropriate patient populations, will yield meaningful improvements in clinical outcomes.

Expression of aldehyde dehydrogenase 1 (ALDH1) is associated with basal-like markers and features of aggressive tumours in African breast cancer

BACKGROUND

Putative breast cancer stem cells might express surface markers such as aldehyde dehydrogenase 1 (ALDH1) and BMI-1 proteins. The aim of this study was to explore the expression of these proteins in breast cancers from an African population and their associations with the basal-like phenotype (BLP) and other molecular characteristics.

METHODS

We analysed 192 paraffin-embedded breast carcinoma samples by tissue microarrays and immunohistochemical methods.

RESULTS

In total, 88 tumours (48%) expressed ALDH1, whereas 46 (25%) expressed BMI-1 protein. Expression of ALDH1 was associated with high histological grade (P<0.0005), high mitotic count (P<0.0005), high nuclear grade (P<0.0005), oestrogen receptor (ER) negativity (P<0.0005), progesterone receptor (PR) negativity (P=0.009), p53 expression (P=0.034), cytokeratin 5/6 positivity (P=0.008), epidermal growth factor receptor (EGFR) expression (P=0.015) and the BLP (P<0.0005), whereas it was inversely associated with BMI-1 staining (P=0.009). On the other hand, BMI-1 expression was associated with low histological grade (P=0.004) and ER positivity (P=0.001).

CONCLUSION

There was a high prevalence of ALDH1 expression among breast carcinomas and associations with basal markers and features of aggressive tumours. Studies are required to elucidate the importance of these findings for improved understanding of breast cancer biology.