Among triple-negative breast cancers, HER2(0) breast cancer shows a strong tendency to be basal-like compared with HER2(1+) breast cancer: preliminary results

Molecular targets and therapeutic strategies for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is known for its heterogeneous complexity and is often difficult to treat. TNBC lacks the expression of major hormonal receptors like estrogen receptor, progesterone receptor, and human epidermal growth factor receptor-2 and is further subdivided into androgen receptor (AR) positive and AR negative. In contrast, AR negative is also known as quadruple-negative breast cancer (QNBC). Compared to AR-positive TNBC, QNBC has a great scarcity of prognostic biomarkers and therapeutic targets. QNBC shows excessive cellular growth and proliferation of tumor cells due to increased expression of growth factors like EGF and various surface proteins. This study briefly reviews the limited data available as protein biomarkers that can be used as molecular targets in treating TNBC as well as QNBC. Targeted therapy and immune checkpoint inhibitors have recently changed cancer treatment. Many studies in medicinal chemistry continue to focus on the synthesis of novel compounds to discover new antiproliferative medicines capable of treating TNBC despite the abundance of treatments currently on the market. Drug repurposing is one of the therapeutic methods for TNBC that has been examined. Moreover, some additional micronutrients, nutraceuticals, and functional foods may be able to lower cancer risk or slow the spread of malignant diseases that have already been diagnosed with cancer. Finally, nanomedicines, or applications of nanotechnology in medicine, introduce nanoparticles with variable chemistry and architecture for the treatment of cancer. This review emphasizes the most recent research on nutraceuticals, medication repositioning, and novel therapeutic strategies for the treatment of TNBC.

A nine-lncRNA signature predicts distant relapse-free survival of HER2-negative breast cancer patients receiving taxane and anthracycline-based neoadjuvant chemotherapy

Multi-gene prognostic signatures of long non-coding RNAs (lncRNAs) provide new insights into mechanisms of HER2-negative breast cancer development and progression, and predict distant relapse-free survival (DRFS) of patients receiving taxane and anthracycline-based neoadjuvant chemotherapy. The aim of this study was to develop such a multi-lncRNAs signature. Optimal multiple candidate signature lncRNAs associated with DRFS were firstly identified by a univariate Cox proportional hazard regression survival analysis and a robust likelihood-based survival analysis of the GEO dataset GSE25055. A nine-lncRNA prognostic risk score model Risk Score = 0.0289 × EXP_LOC100507388 - 0.0814 × EXP_LINC00094 - 0.2422 × EXP_SMG7-AS1 - 0.2433 × EXP_PP14571 + 0.4690 × EXP_ASAP1-IT1 - 0.2483 × EXP_LOC103344931 - 0.2464 × EXP_FAM182A + 0.3349 × EXP_HCG26 - 0.0216 × EXP_LINC00963 was built according to the coefficients of multivariate survival analysis of the association between the candidate lncRNAs and survival. EXP_lncRNA was the standardized log2-transformed expression level of the gene. According to this model, higher scores predicted lower survival probability. The area under Receiver operating characteristic (ROC) curve (AUC) was 0.777 to 0.823 from 1- to 7- year survival rate. The model and its individual lncRNAs differentiated survival probability between the higher scores (expression) and the lower scores (expression). The nine-lncRNA signature had the robust prognostic power compared with ER, PR, tumor size (T), lymph node invasion (N), TNM stage, pathologic response, chemosensitivity prediction and PAM50 signature. These results were consistent with those based on the GEO dataset GSE25065. The predictive nomograms integrating both the nine-lncRNA signature classifier and clinical-pathological risk factors were robust in predicting 1-, 3- and 5- year survival probabilities. These results supported that the nine-lncRNA signature was a robust and effective model in predicting DRFS of patients with HER2-negative breast cancer following taxane and anthracycline-based neoadjuvant chemotherapy.

Suppression of PTEN/AKT signaling decreases the expression of TUBB3 and TOP2A with subsequent inhibition of cell growth and induction of apoptosis in human breast cancer MCF-7 cells via ATP and caspase-3 signaling pathways

The aim of the present study was to evaluate the effects of PTEN/AKT signaling on TUBB3 and TOP2A expression and on the subsequent cell growth of human breast cancer MCF-7 cells. We found that the disease-free survival (DFS) and overall survival (OS) of breast cancer patients with TUBB3‑positive tumors were lower than these rates in the patients with TUBB3-negative tumors. Meanwhile, DFS and OS of breast cancer patients with TOP2A-positive tumors were also lower than these rates in patients with TOP2A-negative tumors. Suppression of PTEN reduced the protein expression of TUBB3 and TOP2A in MCF-7 cells. Suppression of PTEN also reduced cell proliferation and induced apoptosis and caspase-3 activity in MCF-7 cells. Moreover, an increase in ATP also reduced TUBB3 and TOP2A protein expression, reduced cell proliferation and induced apoptosis and caspase-3 activity in the MCF-7 cells following suppression of PTEN. Suppression of phosphorylation-AKT (p-AKT) reduced the protein expression of TUBB3 and TOP2A in the MCF-7 cells. Suppression of p-AKT also reduced cell proliferation and induced apoptosis and caspase-3 activity in the MCF-7 cells. Then, ATP also reduced TUBB3 and TOP2A protein expression, reduced cell proliferation and induced apoptosis and caspase-3 activity in MCF-7 cells following suppression of p-AKT. These results suggest that PTEN/AKT signaling affects the expression of TUBB3 and TOP2A reducing cell growth and inducing apoptosis of human breast cancer MCF-7 cells through ATP and caspase-3 signaling pathways. TUBB3 and TOP2A may be promising prognostic markers for the efficacy of adjuvant cisplatin-based chemotherapy.

HER2 induced EMT and tumorigenicity in breast epithelial progenitor cells is inhibited by coexpression of EGFR

The members of the epidermal growth factor receptor (EGFR) kinase family are important players in breast morphogenesis and cancer. EGFR2/HER2 and EGFR expression have a prognostic value in certain subtypes of breast cancer such as HER2-amplified, basal-like and luminal type B. Many clinically approved small molecular inhibitors and monoclonal antibodies have been designed to target HER2, EGFR or both. There is, however, still limited knowledge on how the two receptors are expressed in normal breast epithelium, what effects they have on cellular differentiation and how they participate in neoplastic transformation. D492 is a breast epithelial cell line with stem cell properties that can undergo epithelial to mesenchyme transition (EMT), generate luminal- and myoepithelial cells and form complex branching structures in three-dimensional (3D) culture. Here, we show that overexpression of HER2 in D492 (D492^HER2) resulted in EMT, loss of contact growth inhibition and increased oncogenic potential in vivo. HER2 overexpression, furthermore, inhibited endogenous EGFR expression. Re-introducing EGFR in D492^HER2 (D492^HER2/EGFR) partially reversed the mesenchymal state of the cells, as an epithelial phenotype reappeared both in 3D cultures and in vivo. The D492^HER2/EGFR xenografts grow slower than the D492^HER2 tumors, while overexpression of EGFR alone (D492^EGFR) was not oncogenic in vivo. Consistent with the EGFR-mediated epithelial phenotype, overexpression of EGFR drove the cells toward a myoepithelial phenotype in 3D culture. The effect of two clinically approved anti-HER2 and EGFR therapies, trastuzumab and cetuximab, was tested alone and in combination on D492^HER2 xenografts. While trastuzumab had a growth inhibitory effect compared with untreated control, the effect of cetuximab was limited. When administered in combination, the growth inhibitory effect of trastuzumab was less pronounced. Collectively, our data indicate that in HER2-overexpressing D492 cells, EGFR can behave as a tumor suppressor, by pushing the cells towards epithelial differentiation.

Effect of sodium/iodide symporter (NIS)-mediated radioiodine therapy on estrogen receptor-negative breast cancer

Since the sodium/iodide symporter (NIS) stimulates the iodine uptake in normal lactating breast, our study aimed to study the effect of NIS-mediated radioiodide therapy on ER-negative breast cancers. A recombinant lentivirus plasmid encoding the human NIS (hNIS) gene and firefly luciferase (Fluc) was constructed. MDA-MB-231 cells were transfected with the recombinant lentivirus, and the hNIS gene expression was identified by western blot analysis and real-time PCR. Tissue-specific expression of the NIS gene was confirmed by immunohistochemical (IHC) staining. Functional NIS activity in the MDA-hNIS cells was confirmed by the uptake of 131I and cytotoxicity assays. The relative expression level of hNIS mRNA exhibited a 10-fold higher expression in the MDA-hNIS cells compared with the level in the control cells without the endogenous NIS gene. Abundant expression of hNIS protein was noted in the cell membrane compared to the cytoplasm which confirmed the efficient expression of the functional hNIS gene. Iodine uptake into the MDA-hNIS cells was rapid, reaching a maximum after 15 min, followed by a decline. Exposure of the MDA-hNIS cells with 131I resulted in a time-dependent reduction in colony formation compared with the survival of the control (MDA) cells. Our results confirmed that NIS overexpression enhances the sensitivity of ER-negative breast cancer cells to radioiodide therapy.

Regional differences in breast cancer biomarkers in american Indian and Alaska native women

BACKGROUND

Breast cancer is not a homogeneous disease, but several different and unique subtypes defined by gene expression analysis. Incidence and mortality rates vary by almost 3-fold between Alaska (highest) and the Southwestern tribes (lowest). We hypothesized that these differences may be due to, in part, varying levels of biologic tumor aggressiveness.

METHODS

A biorepository of the North Central Cancer Treatment Group with 95 cases of American Indian and Alaska Native (AIAN) women with adenocarcinoma of the breast surgically treated from 1990 to 2000 was tested for several biomarkers. Comparison distributions of biomarker values across state of residence using t tests for continuous (p53, MIB-1, cyclin D) and ordinally scaled markers [EGF receptor (EGFR), BCL-2, Her2] and χ(2) tests of significance for binary markers [estrogen receptor (ER), progesterone receptor (PR)] were done.

RESULTS

Significant regional differences in some biomarker expression levels were seen. No increase was observed in "triple-negative" breast cancer or Her2 overexpression in these cases.

CONCLUSIONS

Despite a 3-fold difference in breast cancer mortality in Alaska Native versus Southwestern American Indians, standard biomarkers such as ER, PR, and Her2 neu expression did not explain the disparity.

IMPACT

There is a need for research to understand the biologic basis of breast cancer disparities in AIAN women. Potential for a prospective trial will be explored with tribes.

Differential expression of testin and survivin in breast cancer subtypes

Testin (TES) is a putative tumour-suppressor gene downregulated in various types of cancers. Survivin is a nodal protein involved in multiple signalling pathways, tumour maintenance and inhibition of apoptosis. Previous studies indicate that TES and survivin can functionally interact and modulate cell death and proliferation in breast cancer cells. The aim of the present study was to investigate the expression and prognostic relevance of TES and survivin in breast cancer subtypes examining a large cohort of breast cancer patients. We determined the expression of TES and survivin by immunohistochemistry (IHC) in tissue samples from 242 breast cancer patients diagnosed between 1981 and 2009. The expression of these proteins was compared with clinical and pathological data. There was a significant association of nuclear survivin overexpression and TES downregulation with triple-negative tumours [P=0.009; univariate odds ratio (OR), 3.20; 95% CI, 1.34-7.66] (P=0.018; multivariate OR, 2.90; 95% CI, 1.20‑6.97). A further significant correlation was observed between TES downregulation and the luminal B subtype (P=0.019, univariate OR: 2.90; 95% CI, 1.19‑7.06) (P=0.032, multivariate OR, 2.67; 95% CI, 1.09-6.65), independent of survivin expression. Our results demonstrated a statistically significant association between TES downregulation and highly aggressive breast tumour subtypes, such as triple-negative and luminal B tumours, along with the prognostic relevance of nuclear expression of survivin. To our knowledge, this is the first demonstration of such an association.