Triple-negative breast cancer. Curr Opin Oncol. 2008;20:614-620. [PMID: 18841042 DOI: 10.1097/cco.0b013e328312efba]

Free drug and ROS-responsive nanoparticle delivery of synergistic doxorubicin and olaparib combinations to triple negative breast cancer models

Combinations of the topoisomerase II inhibitor doxorubicin and the poly (ADP-ribose) polymerase inhibitor olaparib offer potential drug-drug synergy for the treatment of triple negative breast cancers (TNBC). In this study we performed in vitro screening of combinations of these drugs, administered directly or encapsulated within polymer nanoparticles, in both 2D and in 3D spheroid models of breast cancer. A variety of assays were used to evaluate drug potency, and calculations of combination index (CI) values indicated that synergistic effects of drug combinations occurred in a molar-ratio dependent manner. It is suggested that the mechanisms of synergy were related to enhancement of DNA damage as shown by the level of double-strand DNA breaks, and mechanisms of antagonism associated with mitochondrial mediated cell survival, as indicated by reactive oxygen species (ROS) generation. Enhanced drug delivery and potency was observed with nanoparticle formulations, with a greater extent of doxorubicin localised to cell nuclei as evidenced by microscopy, and higher cytotoxicity at the same time points compared to free drugs. Together, the work presented identifies specific combinations of doxorubicin and olaparib which were most effective in a panel of TNBC cell lines, explores the mechanisms by which these combined agents might act, and shows that formulation of these drug combinations into polymeric nanoparticles at specific ratios conserves synergistic action and enhanced potency in vitro compared to the free drugs.

Pathological complete response following cisplatin or carboplatin-based neoadjuvant chemotherapy for triple-negative breast cancer: A systematic review and meta-analysis

The addition of platinum compounds to standard neoadjuvant chemotherapy (NACT) for triple-negative breast cancer (TNBC) is highly controversial. Platinum agents, such as cisplatin and carboplatin, are DNA-damaging agents which exhibit activity in breast cancer, particularly in the TNBC subgroup. In order to assess the efficacy of each most representative platinum agent (cisplatin and carboplatin) in patients with TNBC treated with NACT, the present study performed a systematic review and meta-analysis of all available published studies on TNBC. A search of PubMed was performed to identify studies that investigated platinum-based NACT in patients with TNBC. The primary endpoints were the pooled rate of the pathological complete response (pCR) between cisplatin vs. carboplatin-based NACT. A total of 24 studies were selected (17 studies for carboplatin and 6 studies for cisplatin and 1 study with both carboplatin and cisplatin, with 20 prospective studies) for the analysis of 1,711 patients with TNBC. Overall, the pooled rate of pCR in patients treated with platinum-based NACT was 48%. No significant differences were observed between the rates of pCR obtained under carboplatin vs cisplatin treatment. The carboplatin pCR rate was 0.470 [95% confidence interval (CI), 0.401-0.539], while the cisplatin pCR rate was 0.473 (95% CI, 0.379-0.568). The comparison between these two categories revealed no significant differences (P=0.959). In the whole, the present study demonstrates that neoadjuvant platinum-based chemotherapy improves the pCR rate in patients with TNBC, regardless of the platinum agent used. Carboplatin may thus represent a viable option due to its more favorable toxicity profile.

Presence of high-risk HPVs, EBV, and MMTV in human triple-negative breast cancer

Breast cancer, the most frequent disease amongst women worldwide, accounts for the highest cancer-related mortality rate. Triple-negative breast cancer (TNBC) subtype encompasses ~15% of all breast cancers and lack estrogen, progesterone, and HER2 receptors. Although risk factors for breast cancer are well-known, factors underpinning breast cancer onset and progression remain unknown. Recent studies suggest the plausible role of oncoviruses including human papillomaviruses (HPVs), Epstein-Barr virus (EBV), and mouse mammary tumor virus (MMTV) in breast cancer pathogenesis. However, the role of these oncoviruses in TNBC is still unclear. In the current study, we explored the status of high-risk HPVs, EBV, and MMTV in a well-defined TNBC cohort from Croatia in comparison to 16 normal/non TNBC samples (controls) using polymerase chain reaction assay. We found high-risk HPVs and EBV present in 37/70 (53%) and 25/70 (36%) of the cases, respectively. The most common HPV types are 52, 45, 31, 58 and 68. We found 16% of the samples positive for co-presence of high-risk HPVs and EBV. Moreover, our data revealed that 5/70 (7%) samples are positive for MMTV. In addition, only 2/70 (3%) samples had co-presence of HPVs, EBV, and MMTV without any significant association with the clinicopathological variables. While, 6/16 (37.5%) controls were positive for HPV (p = .4), EBV was absent in all controls (0/16, 0%) (p = .01). In addition, we did not find the co-presence of the oncoviruses in the controls (p > .05). Nevertheless, further investigations are essential to understand the underlying mechanisms of multiple-oncogenic viruses' interaction in breast carcinogenesis, especially TNBC.

Novel Long Noncoding RNA 005620 Induces Epirubicin Resistance in Triple-Negative Breast Cancer by Regulating ITGB1 Expression

Triple-negative breast cancer (TNBC) is often treated with anthracyclines (e.g., epirubicin or doxorubicin), but very little is known about anthracycline resistance, especially epirubicin resistance in TNBC. To identify novel long noncoding RNAs (lncRNAs) involved in epirubicin resistance in TNBC, we established a new TNBC MDA-MB-231 cell line that was resistant to epirubicin (Epi-R). A total of 12 differentially expressed lncRNAs were identified using RNA sequencing analysis of Epi-R cells. Among these lncRNAs, we found a novel intronic lncRNA, lnc005620, was highly expressed in Epi-R cells and human TNBC tissues. Further gain- and loss-of-function studies demonstrated that lnc005620 played an oncogenic role and partially abrogated the effects of epirubicin on TNBC cells. Using iTRAQ proteomics analysis, we found that three members of the integrin family, integrin β4, integrin β1 and integrin α6, were all upregulated in Epi-R MDA-MB-231 cells. Integrin β1, encoded by the ITGB1 gene, was validated to be a downstream target of lnc005620 in Epi-R MDA-MB-231 cells. Our study demonstrates that novel lnc005620 promotes TNBC progression and chemoresistance to epirubicin via integrin β1 both in vitro and in vivo and provides a promising therapeutic target for TNBC patients in terms of enhancing the benefits of epirubicin treatment.

MiRNA and LncRNA as Potential Biomarkers in Triple-Negative Breast Cancer: A Review

Noncoding RNAs (ncRNAs) include a diverse range of RNA species, including microRNAs (miRNAs) and long noncoding RNAs (lncRNAs). MiRNAs, ncRNAs of approximately 19-25 nucleotides in length, are involved in gene expression regulation either via degradation or silencing of the messenger RNAs (mRNAs) and have roles in multiple biological processes, including cell proliferation, differentiation, migration, angiogenesis, and apoptosis. LncRNAs, which are longer than 200 nucleotides, comprise one of the largest and most heterogeneous RNA families. LncRNAs can activate or repress gene expression through various mechanisms, acting alone or in combination with miRNAs and other molecules as part of various pathways. Until recently, most research has focused on individual lncRNA and miRNA functions as regulators, and there is limited available data on ncRNA interactions relating to the tumor growth, metastasis, and therapy of cancer, acting either on mRNA alone or as competing endogenous RNA (ceRNA) networks. Triple-negative breast cancer (TNBC) represents approximately 10%-20% of all breast cancers (BCs) and is highly heterogenous and more aggressive than other types of BC, for which current targeted treatment options include hormonotherapy, PARP inhibitors, and immunotherapy; however, no targeted therapies for TNBC are available, partly because of a lack of predictive biomarkers. With advances in proteomics, new evidence has emerged demonstrating the implications of dysregulation of ncRNAs in TNBC etiology. Here, we review the roles of lncRNAs and miRNAs implicated in TNBC, including their interactions and regulatory networks. Our synthesis provides insight into the mechanisms involved in TNBC progression and has potential to aid the discovery of new diagnostic and therapeutic strategies.

Circulating miRNAs in HER2-Positive and Triple Negative Breast Cancers: Potential Biomarkers and Therapeutic Targets

Breast cancer is one of the most prevalent diseases among women worldwide and is highly associated with cancer-related mortality. Of the four major molecular subtypes, HER2-positive and triple-negative breast cancer (TNBC) comprise more than 30% of all breast cancers. While the HER2-positive subtype lacks estrogen and progesterone receptors and overexpresses HER2, the TNBC subtype lacks estrogen, progesterone and HER2 receptors. Although advances in molecular biology and genetics have substantially ameliorated breast cancer disease management, targeted therapies for the treatment of estrogen-receptor negative breast cancer patients are still restricted, particularly for TNBC. On the other hand, it has been demonstrated that microRNAs, miRNAs or small non-coding RNAs that regulate gene expression are involved in diverse biological processes, including carcinogenesis. Moreover, circulating miRNAs in serum/plasma are among the most promising diagnostic/therapeutic tools as they are stable and relatively easy to quantify. Various circulating miRNAs have been identified in several human cancers including specific breast cancer subtypes. This review aims to discuss the role of circulating miRNAs as potential diagnostic and prognostic biomarkers as well as therapeutic targets for estrogen-receptor negative breast cancers, HER2+ and triple negative.

Development and Testing of the CAHPS Cancer Care Survey

PURPOSE

The Consumer Assessment of Healthcare Providers and Systems (CAHPS) Cancer Care Survey is a systematic assessment of health care experiences of patients with cancer. It supports comparisons among all cancer treatment settings and modalities.

METHODS

Formative research included 16 focus groups with patients receiving treatment and family members; advice from a panel of oncology and quality improvement experts; and interviews with stakeholders representing oncology associations, accredited cancer centers, and community oncology practices. We conducted cognitive tests of the instrument and field tests at six cancer centers and four community oncology practices, after which the survey was finalized and obtained the CAHPS trademark.

RESULTS

The survey includes 56 questions that form six core composite measures (Getting Timely Care; Supporting Patient Self-Management; Available to Provide Care and Information; Provider Communication; Care Coordination; and Courteous Office Staff); two single-item measures of family participation in care and interpreter services; and two global ratings of cancer care and the treatment team. Sixteen additional items form three supplemental composite measures: Shared Decision-Making, Keeping Patients Informed, and Access to Care.

CONCLUSION

Mail-only, mail-telephone mixed-mode, and Web-mail mixed-mode data collection methods are recommended. The questionnaires and instructions for use are free and available in English and Spanish on the CAHPS Website (www.ahrq.gov/cahps).

Weekly carboplatin plus neoadjuvant anthracycline-taxane-based regimen in early triple-negative breast cancer: a prospective phase II trial by the Breast Cancer Task Force of the Belgian Society of Medical Oncology (BSMO)

AIM

To evaluate the pCR rate and toxicity of the addition of weekly carboplatin (Cp) to paclitaxel (wP) and dose-dense (dd) epirubicin/cyclophosphamide (EC) in an open-label phase II study in TNBC patients.

METHODS

Patients were included if they had stage II and III TNBC and received wP (80 mg/m²/week) concurrent with weekly Cp (AUC = 2) for 12 weeks, followed by bi-weekly epirubicin (90 mg/m²) and cyclophosphamide (600 mg/m²) plus granulocyte colony-stimulating factor (G-CSF) for four cycles, followed by surgery. The primary endpoint was the rate of pCR [(ypT0/isypN0)]. Secondary endpoints included safety and drug delivery.

RESULTS

Sixty-three eligible patients were included. Median age was 51 years (range 29-74); 88.9% had stage II disease, 46% were clinically node positive, and 77.8% had grade 3 tumors. Fifty-four percent achieved a pCR. Twelve percent missed two or more doses of wP, whereas at least two cycles of EC were missed in 9.5%. The rate of tolerance without delays or dose reductions is very low (16%). Sixty-two percent had G3/4 neutropenia. Febrile neutropenia occurred in 18 patients of which more than eighty percent occurred during EC despite primary prophylaxis with G-CSF. Thrombocytopenia grade 3/4 was noticed in 11 pts. Three patients developed grade 3 peripheral neuropathy.

CONCLUSION

The addition of weekly carboplatin to neoadjuvant paclitaxel and dd EC leads to a pCR rate comparable to prior studies (54%). However, hematological toxicity and febrile neutropenia rate was unexpectedly high. Future investigations could focus on reversing the sequence, which may lead to better hematological tolerability.

Triple Negative Breast Cancer Profile, from Gene to microRNA, in Relation to Ethnicity

Breast cancer is the most frequent cause of cancer-related deaths among women worldwide. It is classified into four major molecular subtypes. Triple-negative breast cancers (TNBCs), a subgroup of breast cancer, are defined by the absence of estrogen and progesterone receptors and the lack of HER-2 expression; this subgroup accounts for ~15% of all breast cancers and exhibits the most aggressive metastatic behavior. Currently, very limited targeted therapies exist for the treatment of patients with TNBCs. On the other hand, it is important to highlight that knowledge of the molecular biology of breast cancer has recently changed the decision-making process regarding the course of cancer therapies. Thus, a number of new techniques, such as gene profiling and sequencing, proteomics, and microRNA analysis have been used to explore human breast carcinogenesis and metastasis including TNBC, which consequently could lead to new therapies. Nevertheless, based on evidence thus far, genomics profiles (gene and miRNA) can differ from one geographic location to another as well as in different ethnic groups. This review provides a comprehensive and updated information on the genomics profile alterations associated with TNBC pathogenesis associated with different ethnic backgrounds.

CXCR2 is a novel cancer stem-like cell marker for triple-negative breast cancer

Background

Breast cancer is the leading cause of mortality from cancer in women worldwide, and cancer stem-like cell (CSC) is responsible for failure treatment of breast cancer. It plays an important role in resistant disease and metastasis. CD44/CD24 and ALDH are well-accepted protein markers of breast CSC, and it was reported that distinct subtypes of breast CSC were identified by the 2 markers. It is possible that there are various kinds of breast CSC which could be identified by different markers, and CSC markers utilized at present are not enough to fully understand breast CSC. Finding out more novel CSC markers is necessary. CXCR2 is involved in breast cancer metastasis, treatment resistance, and recurrence and has positive cross-talk with known breast CSC protein markers. It can be concluded that CXCR2 is related to breast CSC, and further study is in need.

Results

In this study, we assessed expression of CXCR2 with immunohistochemistry in breast cancer tissues from 37 patients and discovered that level of CXCR2 was significantly lower in triple-negative breast cancer (TNBC) compared with non-TNBC. CXCR2 expression decreased in estrogen receptor-negative or HER2-negative breast cancer, but not progesterone receptor-negative counterparts. By immunofluorescence, we observed high coexpression rate of CXCR2 and CSC-related proteins, including NANOG and SOX2. To prove our speculation that CXCR2 was a novel CSC marker for TNBC, we used 4T1 cell, which is a TNBC cell line, to analyze CXCR2-positive subpopulations and observed that CXCR2-positive 4T1 cells showed characteristics of CSC, including resistance to cisplatinum, radiation, and hypoxia, low proportion (around 1%), much more tumor xenografts, tumor spherule formation, and higher levels of CSC-related mRNA compared with CXCR2-negative cells.

Conclusion

CXCR2 is an acceptable and newly discovered CSC marker for only TNBC.

Medullary Breast Carcinoma and Invasive Ductal Carcinoma: A Review Study

BACKGROUND

Medullary breast carcinoma (MBC) is a unique histological subtype of breast cancer. The present study aimed to evaluate the classic and non-classic characteristics of MBC and its differences with IDC. The present review study incorporates 22 years of practical experience from a breast disease research center-based series of cases.

METHODS

Retrospectively, the medical records of 3,246 patients were reviewed in the Breast Disease Research Center, Shiraz University of Medical Science (Shiraz, Iran), from December 1993 to December 2015. The tumor size, lymph node metastasis, pathologic stage, nuclear and histological grade, hormonal receptor status, recurrence, disease-free, and overall survival were reviewed. Differences between medullary breast carcinoma and invasive ductal carcinoma were analyzed statistically using the Chi-square, Fischer, independent-sample t test, and Kaplan-Meier analysis (SPSS version 19.0). P<0.05 were considered statistically significant.

RESULTS

A total of 179 patients were identified with MBC and 3,067 patients were identified with IDC. The MBC group had a significant association with a higher histological grade (P<0.001) as well as negative estrogen receptor (P<0.001), progesterone receptor (P<0.001), and HER-2 (P=0.004) status. The MBC patients predominantly had triple-negative breast cancer (TNBC) according to the molecular subtype (P<0.001). In local invasion, MBC was less invasive compared to IDC (P<0.001). The disease-free survival (DFS) and overall survival (OS) differed significantly between the MBC and IDC groups (5-year DFS: 94.2% vs. 86.3%, P=0.008; 5-year OS: 98.1% vs. 92.8%, P=0.004).

CONCLUSION

Despite the poor and aggressive pathological features of MBC, its clinical outcome is more favorable compared to IDC. Our findings can be useful in improvement of diagnosis and treatment of less known breast cancer subtypes, such as MBC.

Tumor regression and modulation of gene expression via tumor-targeted tocotrienol niosomes

AIM

To develop 6-O-palmitoyl-ascorbic acid-based niosomes targeted to transferrin receptor for intravenous administration of tocotrienols (T3) in breast cancer.

MATERIALS & METHODS

Niosomes were prepared using film hydration and ultrasonication methods. Transferrin was coupled to the surface of niosomes via chemical linker. Nanovesicles were characterized for size, zeta potential, morphology, stability and biological efficacy.

RESULTS

When evaluated in MDA-MB-231 cells, entrapment of T3 in niosomes caused 1.5-fold reduction in IC₅₀ value compared with nonformulated T3. In vivo, the average tumor volume of mice treated with tumor-targeted niosomes was 12-fold lower than that of untreated group, accompanied by marked downregulation of three genes involved in metastasis.

CONCLUSION

Findings suggested that tumor-targeted niosomes served as promising delivery system for T3 in cancer therapy.

Addressing the challenges of applying precision oncology

Precision oncology is described as the matching of the most accurate and effective treatments with the individual cancer patient. Identification of important gene mutations, such as BRCA1/2 that drive carcinogenesis, helped pave the way for precision diagnosis in cancer. Oncoproteins and their signaling pathways have been extensively studied, leading to the development of target-based precision therapies against several types of cancers. Although many challenges exist that could hinder the success of precision oncology, cutting-edge tools for precision diagnosis and precision therapy will assist in overcoming many of these difficulties. Based on the continued rapid progression of genomic analysis, drug development, and clinical trial design, precision oncology will ultimately become the standard of care in cancer therapeutics.

Dual-targeted hybrid nanoparticles of synergistic drugs for treating lung metastases of triple negative breast cancer in mice

Lung metastasis is the major cause of death in patients with triple negative breast cancer (TNBC), an aggressive subtype of breast cancer with no effective therapy at present. It has been proposed that dual-targeted therapy, ie, targeting chemotherapeutic agents to both tumor vasculature and cancer cells, may offer some advantages. The present work was aimed to develop a dual-targeted synergistic drug combination nanomedicine for the treatment of lung metastases of TNBC. Thus, Arg-Gly-Asp peptide (RGD)-conjugated, doxorubicin (DOX) and mitomycin C (MMC) co-loaded polymer-lipid hybrid nanoparticles (RGD-DMPLN) were prepared and characterized. The synergism between DOX and MMC and the effect of RGD-DMPLN on cell morphology and cell viability were evaluated in human MDA-MB-231 cells in vitro. The optimal RGD density on nanoparticles (NPs) was identified based on the biodistribution and tumor accumulation of the NPs in a murine lung metastatic model of MDA-MB-231 cells. The microscopic distribution of RGD-conjugated NPs in lung metastases was examined using confocal microscopy. The anticancer efficacy of RGD-DMPLN was investigated in the lung metastatic model. A synergistic ratio of DOX and MMC was found in the MDA-MB-231 human TNBC cells. RGD-DMPLN induced morphological changes and enhanced cytotoxicity in vitro. NPs with a median RGD density showed the highest accumulation in lung metastases by targeting both tumor vasculature and cancer cells. Compared to free drugs, RGD-DMPLN exhibited significantly low toxicity to the host, liver and heart. Compared to non-targeted DMPLN or free drugs, administration of RGD-DMPLN (10 mg/kg, iv) resulted in a 4.7-fold and 31-fold reduction in the burden of lung metastases measured by bioluminescence imaging, a 2.4-fold and 4.0-fold reduction in the lung metastasis area index, and a 35% and 57% longer median survival time, respectively. Dual-targeted RGD-DMPLN, with optimal RGD density, significantly inhibited the progression of lung metastasis and extended host survival.

Long noncoding RNAs (lncRNAs) in triple negative breast cancer

Long noncoding RNAs (lncRNAs) are dysregulated in many cancer types, which are believed to play crucial roles in regulating several hallmarks of cancer biology. Triple Negative Breast Cancer (TNBC) is a very aggressive subtype of normal breast cancer, which has features of negativity for ER, PR, and HER2. Great efforts have been made to identify an association between lncRNAs expression profiles and TNBC, and to understand the functional role and molecular mechanism on aberrant-expressed lncRNAs. In this review, we summarized the existed knowledge on the systematics, biology, and function of lncRNAs. The advances from the most recent studies of lncRNAs in the predicament of breast cancer, TNBC, are highlighted, especially the functions of specifically selected lncRNAs. We also discussed the potential value of these lncRNAs in TNBC, providing clues for the diagnosis and treatments of TNBC.

Triple Negative Breast Cancer at the University Hospital Mohammed VI – Oujda

Introduction: The triple-negative breast cancer (TNBC), defined by the absence of receptors to oestrogen and progesterone and no histochemical expression of human epidermal receptor -2, is associated with a particularly aggressive behavior. The aim of our study was to determine the clinico-pathological, therapeutic and prognostic features associated with this type of breast cancer in Morocco. Methods: A cohort retrospective study, spread over 3 years, was conducted of 116 breast cancer patients, diagnosed between January 2009 and December 2011 at the Regional Center of Oncology. Epidemiological, clinical, histological and therapeutic data were analyzed. Survival curves at 3 years were estimated by Kaplan-Meier analysis with use of the log-rank test. Results: The proportion of triple-negative breast cancer in our series was 13.2%. The average age was 46.5 years and 20,7% had a previous history of familial breast cancer. Some 56,9% of tumors were greater than 3 cm in diameter. infiltrating ductal carcinoma being the histological type in the majority of cases (75.9%). TNBC was most often associated with a high grade, grade III accounting for 50.9%. Vascular invasion was found in 58.6% of cases. Regarding lymph node involvement, 42.2% had positive lymph nodes and 15.5% featured distant metastases. Neoadjuvant chemotherapy was administrated to 20% of patients with a 23.5% complete pathologic response. The rates for overall survival and disease-free-survival at 3 years for localized stages were 70 and 55.6%, respectively. With metastatic lesions, the figures were 27.5% and 10.3% respectively. Conclusion: The TNBC is correlated with a poor prognosis with a high mortality and early relapse requiring identification of new target therapies and markers for prediction of tumoral response to various treatments.

CXCL16/CXCR6 chemokine signaling mediates breast cancer progression by pERK1/2-dependent mechanisms

Our previous studies demonstrate that CXCL6/CXCR6 chemokine axis induces prostate cancer progression by the AKT/mTOR signaling pathway; however, its role and mechanisms underlying invasiveness and metastasis of breast cancer are yet to be elucidated. In this investigation, CXCR6 protein expression was examined using high-density tissue microarrays and immunohistochemistry. Expression of CXCR6 shows a higher epithelial staining in breast cancer nest site and metastatic lymph node than the normal breast tissue, suggesting that CXCR6 may be involved in breast cancer (BC) development. In vitro and in vivo experiments indicate that overexpression of CXCR6 in BC cells has a marked effect on increasing cell migration, invasion and metastasis. In contrast, reduction of CXCR6 expression by shRNAs in these cells greatly reduce its invasion and metastasis ability. Mechanistic analyses show that CXCL16/CXCR6 chemokine axis is capable of modulating activation of RhoA through activating ERK1/2 signaling pathway, which then inhibits the activity of cofilin, thereby enhancing the stability of F-actin, responsible for invasiveness and metastasis of BC.

Taken together, our data shows for the first time that the CXCR6 / ERK1/2/ RhoA / cofilin /F-actin pathway plays a central role in the development of BC. Targeting the signaling pathway may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for BC.

Biomarkers in triple negative breast cancer: A review

Breast cancer is an intrinsically heterogeneous disease. In the world about 1 million cases of breast cancer are diagnosed annually and more than 170000 are triple-negative. Characteristic feature of triple negative breast cancer (TNBC) is that it lacks expression of oestrogen, progesterone and human epidermal growth factor receptor-2/neu receptors. They comprise 15%-20% of all breast cancers. We did a systematic review of PubMed and conference databases to identify studies published on biomarkers in TNBC. We included studies with biomarkers including: Epidermal growth factor receptor, vascular endothelial growth factor, c-Myc, C-kit and basal cytokeratins, Poly(ADP-ribose) polymerase-1, p53, tyrosinase kinases, m-TOR, heat and shock proteins and TOP-2A in TNBC. We also looked for studies published on synthetic lethality and inhibition of angiogenesis, growth, and survival pathways. TNBC is a complex disease subtype with many subclasses. Majority TNBC have a basal-like molecular phenotype by gene expression profiling. Their clinical and pathologic features overlap with hereditary BRCA1 related breast cancers. Management of these tumours is a challenge to the clinician because of its aggressive behaviour, poor outcome, and absence of targeted therapies. As the complexity of this disease is being simplified over time new targets are also being discovered for the treatment of this disease. There are many biomarkers in TNBC being used in clinical practice. Biomarkers may be useful as prognostic or predictive indicators as well as suggest possible targets for novel therapies. Many targeted agents are being studied for treatment of TNBC.

N-acetylglucosaminyl 1-phosphate transferase: an excellent target for developing new generation breast cancer therapeutic

Studies from our laboratory have explained that breast tumor progression can be attenuated by targeting the N-linked glycoproteins of the tumor microvasculature and that of tumor cells alike with a protein N-glycosylation inhibitor, tunicamycin. Absence of N-glycosylation leads to an accumulation of un- or mis-folded proteins in the ER and the cell develops “ER stress”. The result is cell cycle arrest, and induction of apoptosis mediated by unfolded protein response (upr ) signaling. Tunicamycin inhibited in vitro and in vivo (Matrigel™ implants in athymic nude mice) angiogenesis in a dose dependent manner. The action is irreversible and survived under tumor microenvironment, i.e., in the presence of FGF-2 or VEGF or higher serum concentration. Importantly, tunicamycin prevented the progression of double negative (ER-/PR-/Her2+) and triple negative (ER-/PR-/Her2-) breast tumors by ∼55% - 65% in three weeks in athymic nude mice [Balb/c(nu/nu )]. Analyses of paraffin sections exhibited “ER stress” in both microvasculature and in tumor tissue.

Anti-tumor activity of novel biisoquinoline derivatives against breast cancers

Breast cancer is classified into three groups according to its expression of hormone/growth factor receptors: (i) estrogen receptor (ER) and progesterone receptor (PR)-positive; (ii) human epidermal growth factor receptor 2 (HER2)-positive; and (iii) ER, PR, and HER2-negative (triple-negative). A series of methoxy-substituted biisoquinoline compounds have been synthesized as a potential chemotherapeutic agent for the triple-negative breast cancers which are especially challenging to manage. Structure activity relationship study revealed that rigid 6,6'-dimethoxy biisoquinoline imidazolium compound (1c, DH20931) exhibited the significant growth inhibitory effects on both triple-positive and triple-negative human breast cancer cell lines with IC50 in the range of 0.3-3.9 μM. The 1c (DH20931) is more potent than structurally related noscapine for growth inhibition of MCF7 cell line (IC50=1.3 vs 57 μM) and MDA-MB231 cell line (IC50=3.9 vs 64 μM).

PhenoNet: identification of key networks associated with disease phenotype

MOTIVATION

At the core of transcriptome analyses of cancer is a challenge to detect molecular differences affiliated with disease phenotypes. This approach has led to remarkable progress in identifying molecular signatures and in stratifying patients into clinical groups. Yet, despite this progress, many of the identified signatures are not robust enough to be clinically used and not consistent enough to provide a follow-up on molecular mechanisms.

RESULTS

To address these issues, we introduce PhenoNet, a novel algorithm for the identification of pathways and networks associated with different phenotypes. PhenoNet uses two types of input data: gene expression data (RMA, RPKM, FPKM, etc.) and phenotypic information, and integrates these data with curated pathways and protein-protein interaction information. Comprehensive iterations across all possible pathways and subnetworks result in the identification of key pathways or subnetworks that distinguish between the two phenotypes.

AVAILABILITY AND IMPLEMENTATION

Matlab code is available upon request.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Computerized image analysis for identifying triple-negative breast cancers and differentiating them from other molecular subtypes of breast cancer on dynamic contrast-enhanced MR images: a feasibility study

PURPOSE

To determine the feasibility of using a computer-aided diagnosis (CAD) system to differentiate among triple-negative breast cancer, estrogen receptor (ER)-positive cancer, human epidermal growth factor receptor type 2 (HER2)-positive cancer, and benign fibroadenoma lesions on dynamic contrast material-enhanced (DCE) magnetic resonance (MR) images.

MATERIALS AND METHODS

This is a retrospective study of prospectively acquired breast MR imaging data collected from an institutional review board-approved, HIPAA-compliant study between 2002 and 2007. Written informed consent was obtained from all patients. The authors collected DCE MR images from 65 women with 76 breast lesions who had been recruited into a larger study of breast MR imaging. The women had triple-negative (n = 21), ER-positive (n = 25), HER2-positive (n = 18), or fibroadenoma (n = 12) lesions. All lesions were classified as Breast Imaging Reporting and Data System category 4 or higher on the basis of previous imaging. Images were subject to quantitative feature extraction, feed-forward feature selection by means of linear discriminant analysis, and lesion classification by using a support vector machine classifier. The area under the receiver operating characteristic curve (Az) was calculated for each of five lesion classification tasks involving triple-negative breast cancers.

RESULTS

For each pair-wise lesion type comparison, linear discriminant analysis helped identify the most discriminatory features, which in conjunction with a support vector machine classifier yielded an Az of 0.73 (95% confidence interval [CI]: 0.59, 0.87) for triple-negative cancer versus all non-triple-negative lesions, 0.74 (95% CI: 0.60, 0.88) for triple-negative cancer versus ER- and HER2-positive cancer, 0.77 (95% CI: 0.63, 0.91) for triple-negative versus ER-positive cancer, 0.74 (95% CI: 0.58, 0.89) for triple-negative versus HER2-positive cancer, and 0.97 (95% CI: 0.91, 1.00) for triple-negative cancer versus fibroadenoma.

CONCLUSION

Triple-negative cancers possess certain characteristic features on DCE MR images that can be captured and quantified with CAD, enabling good discrimination of triple-negative cancers from non-triple-negative cancers, as well as between triple-negative cancers and benign fibroadenomas. Such CAD algorithms may provide added diagnostic benefit in identifying the highly aggressive triple-negative cancer phenotype with DCE MR imaging in high-risk women.

Significance of serum vascular endothelial growth factor and cancer antigen 15.3 in patients with triple negative breast cancer

Background

A pilot study was undertaken to find significance of vascular endothelial growth factor (VEGF) and cancer antigen (CA 15.3) in breast cancer patients.

Materials and methods

Total 70 patients with breast cancer were divided into triple negative breast cancer (TNBC) and non-TNBC depending on oestrogen receptors, progesterone receptors or HER-2/neu receptors status. Serum CA 15.3 and VEGF levels were evaluated with enzyme-linked immunosorbent assay at the time of diagnosis and were correlated with age, tumour size and stage of the disease in both the groups. Spearman's test was used to find the correlation.

Results

VEGF levels were found to be >400 pg/ml in 27 patients, 19 (54·33%) of them were TNBC and only 8 (22·87%) non-TNBC. Mean values of the VEGF were, 784·34 pg/ml in TNBC and 334·60 pg/ml non-TNBC patients, respectively. CA 15.3 level was found to be higher in non-TNBC group (60·72 U/ml) than in TNBC group (45·24 U/ml). In all patients significant correlation was found between serum CA 15.3 level and tumour size and stage of the disease. In non-TNBC patients significant correlation was seen between CA 15.3 values and stage of the disease, but VEGF had no correlation with any of the disease parameters. In TNBC patients, there was no correlation between CA 15.3 level and any of the disease parameters but VEGF showed a significant correlation with both tumour size and stage of the disease.

Conclusion

Expression profile of VEGF was high in TNBC than non-TNBC patients. VEGF serves to be a better biomarker as compared with CA 15.3 in TNBC patients.

HIC1 silencing in triple-negative breast cancer drives progression through misregulation of LCN2

The tumor suppressor gene HIC1 is frequently deleted or epigenetically silenced in human cancer, where its restoration may improve cancer prognosis. Here, we report results illuminating how HIC1 silencing alters effect or signals in triple-negative breast cancer (TNBC), which are crucial for its pathogenesis. HIC1 expression was silenced only in TNBC compared with other molecular subtypes of breast cancer. Restoring HIC1 expression in TNBC cells reduced cell migration, invasion, and metastasis, whereas RNAi-mediated silencing of HIC1 in untransformed human breast cells increased their invasive capabilities. Mechanistic investigations identified the small-secreted protein lipocalin-2 (LCN2), as a critical downstream target of HIC1 in TNBC cells. Elevating LCN2 expression in cells expressing HIC1 partially rescued its suppression of cell invasion and metastasis. Notably, autocrine secretion of LCN2 induced by loss of HIC1 activated the AKT pathway through the neutrophil gelatinase-associated lipocalin receptor, which is associated with TNBC progression. Taken together, our findings revealed that the HIC1-LCN2 axis may serve as a subtype-specific prognostic biomarker, providing an appealing candidate target for TNBC therapy.

MR imaging features of triple-negative breast cancers

Triple-negative (TN) breast cancers, which are associated with a more aggressive clinical course and poorer prognosis, often present with benign imaging features on mammography and ultrasound. The purpose of this study was to compare the magnetic resonance imaging features of TN breast cancers with estrogen (ER) and progesterone (PR) positive, human epidermal growth factor receptor (HER2) negative cancers. Retrospective review identified 140 patients with TN breast cancer who underwent a preoperative breast MRI between 2003 and 2008. Comparison was made to 181 patients with ER+/PR+/HER2- cancer. Breast MRIs were independently reviewed by two radiologists blinded to the pathology. Discrepancies were resolved by a third radiologist. TN cancers presented with a larger tumor size (p = 0.002), higher histologic grade (<0.001), and were more likely to be unifocal (p = 0.018) compared with ER+/PR+/HER2- tumors. MRI features associated with TN tumors included mass enhancement (p = 0.026), areas of intratumoral high T2 signal intensity (p < 0.001), lobulated shape (p < 0.001), rim enhancement (p < 0.001), and smooth margins (p = 0.005). Among the TN tumors with marked necrosis, 26% showed a large central acellular zone of necrosis.

TNBCtype: A Subtyping Tool for Triple-Negative Breast Cancer

Motivation:

Triple-negative breast cancer (TNBC) is a heterogeneous breast cancer group, and identification of molecular subtypes is essential for understanding the biological characteristics and clinical behaviors of TNBC as well as for developing personalized treatments. Based on 3,247 gene expression profiles from 21 breast cancer data sets, we discovered six TNBC subtypes from 587 TNBC samples with unique gene expression patterns and ontologies. Cell line models representing each of the TNBC subtypes also displayed different sensitivities to targeted therapeutic agents. Classification of TNBC into subtypes will advance further genomic research and clinical applications.

Result:

We developed a web-based subtyping tool TNBCtype for candidate TNBC samples using our gene expression meta data and classification methods. Given a gene expression data matrix, this tool will display for each candidate sample the predicted subtype, the corresponding correlation coefficient, and the permutation P-value. We offer a user-friendly web interface to predict the subtypes for new TNBC samples that may facilitate diagnostics, biomarker selection, drug discovery, and the more tailored treatment of breast cancer.

A mouse model for triple-negative breast cancer tumor-initiating cells (TNBC-TICs) exhibits similar aggressive phenotype to the human disease

Background

Triple-negative breast cancer (TNBC) exhibit characteristics quite distinct from other kinds of breast cancer, presenting as an aggressive disease--recurring and metastasizing more often than other kinds of breast cancer, without tumor-specific treatment options and accounts for 15% of all types of breast cancer with higher percentages in premenopausal African-American and Hispanic women. The reason for this aggressive phenotype is currently the focus of intensive research. However, progress is hampered by the lack of suitable TNBC cell model systems.

Methods

To understand the mechanistic basis for the aggressiveness of TNBC, we produced a stable TNBC cell line by sorting for 4T1 cells that do not express the estrogen receptor (ER), progesterone receptor (PgR) or the gene for human epidermal growth factor receptor 2 (HER2). As a control, we produced a stable triple-positive breast cancer (TPBC) cell line by transfecting 4T1 cells with rat HER2, ER and PgR genes and sorted for cells with high expression of ER and PgR by flow cytometry and high expression of the HER2 gene by Western blot analysis.

Results

We isolated tumor-initiating cells (TICs) by sorting for CD24⁺/CD44^high/ALDH1⁺ cells from TNBC (TNBC-TICs) and TPBC (TPBC-TICs) stable cell lines. Limiting dilution transplantation experiments revealed that CD24⁺/CD44^high/ALDH1⁺ cells derived from TNBC (TNBC-TICs) and TPBC (TPBC-TICs) were significantly more effective at repopulating the mammary glands of naïve female BALB/c mice than CD24^-/CD44^-/ALDH1^- cells. Implantation of the TNBC-TICs resulted in significantly larger tumors, which metastasized to the lungs to a significantly greater extent than TNBC, TPBC-TICs, TPBC or parental 4T1 cells. We further demonstrated that the increased aggressiveness of TNBC-TICs correlates with the presence of high levels of mouse twenty-five kDa heat shock protein (Hsp25/mouse HspB1) and seventy-two kDa heat shock protein (Hsp72/HspA1A).

Conclusions

Taken together, we have developed a TNBC-TICs model system based on the 4T1 cells which is a very useful metastasis model with the advantage of being able to be transplanted into immune competent recipients. Our data demonstrates that the TNBC-TICs model system could be a useful tool for studies on the pathogenesis and therapeutic treatment for TNBC.

The resistance of breast cancer stem cells to conventional hyperthermia and their sensitivity to nanoparticle-mediated photothermal therapy

Breast tumors contain a small population of tumor initiating stem-like cells, termed breast cancer stem cells (BCSCs). These cells, which are refractory to chemotherapy and radiotherapy, are thought to persist following treatment and drive tumor recurrence. We examined whether BCSCs are similarly resistant to hyperthermic therapy, and whether nanoparticles could be used to overcome this resistance. Using a model of triple-negative breast cancer stem cells, we show that BCSCs are markedly resistant to traditional hyperthermia and become enriched in the surviving cell population following treatment. In contrast, BCSCs are sensitive to nanotube-mediated thermal treatment and lose their long-term proliferative capacity after nanotube-mediated thermal therapy. Moreover, use of this therapy in vivo promotes complete tumor regression and long-term survival of mice bearing cancer stem cell-driven breast tumors. Mechanistically, nanotube thermal therapy promotes rapid membrane permeabilization and necrosis of BCSCs. These data suggest that nanotube-mediated thermal treatment can simultaneously eliminate both the differentiated cells that constitute the bulk of a tumor and the BCSCs that drive tumor growth and recurrence.

A compound that inhibits the HOP-Hsp90 complex formation and has unique killing effects in breast cancer cell lines

The chaperone Hsp90 is required for the correct folding and maturation of certain "client proteins" within all cells. Hsp90-mediated folding is particularly important in cancer cells, because upregulated or mutant oncogenic proteins are often Hsp90 clients. Hsp90 inhibitors thus represent a route to anticancer agents that have the potential to be active against several different types of cancer. Currently, various Hsp90 inhibitors that bind to Hsp90 at its ATP-binding site are in preclinical and clinical trials. Some of the most promising Hsp90 ATP-binding site inhibitors are the well characterized geldanamycin derivative 17-AAG and the recently described compounds PU-H71 and NVP-AUY922. An undesirable characteristic of these compounds is the transcriptional upregulation of Hsp70 that has prosurvival effects. Here we characterize the activity of a new type of chaperone inhibitor, 1,6-dimethyl-3-propylpyrimido[5,4-e][1,2,4]triazine-5,7-dione (named C9 for simplicity). Using purified protein components in vitro, C9 prevents Hsp90 from interacting with the cochaperone HOP and is thus expected to impair the Hsp90-dependent folding pathway in vivo. We show that this compound is effective in killing various breast cancer cell lines including the highly metastatic MDA-MB-231. An important property of this compound is that it does not induce the transcriptional upregulation of Hsp70. Moreover, when cells are treated with a combination of C9 and either 17-AAG or NVP-AUY922, the overexpression of Hsp70 is counteracted considerably and C9's lethal-IC50 decreases compared to its value when added alone.

Combination of thiazolidinedione and hydralazine suppresses proliferation and induces apoptosis by PPARγ up-expression in MDA-MB-231 cells

No proven targeted therapy is currently available for the treatment of triple-negative breast cancer (TNBC). Ligand activation of peroxisome-activated receptor (PPAR)γ induces antitumor effects in cancer but not obviously in TNBC. In TNBC cells, combined treatment with thiazolidinedione and demethylation drugs Hydralazine up-regulated protein and mRNA levels of PPARγ. Besides, the combination of two drugs promote antiproliferative and apoptotic effects in TNBC cells and decrease the proliferation index in the tumor xenografts. Taken together, our results suggest that multidrug regimens including a combination of Thiazolidinedione and Hydralazine may provide a therapeutic advantage in TNBC.

Management options in triple-negative breast cancer

Notorious for its poor prognosis and aggressive nature, triple-negative breast cancer (TNBC) is a heterogeneous disease entity. The nature of its biological specificity, which is similar to basal-like cancers, tumors arising in BRCA1 mutation carriers, and claudin-low cancers, is currently being explored in hopes of finding the targets for novel biologics and chemotherapeutic agents. In this review, we aim to give a broad overview of the disease's nomenclature and epidemiology, as well as the basic mechanisms of emerging targeted therapies and their performance in clinical trials to date.

Triple-negative breast cancer with brain metastases: a comparison between basal-like and non-basal-like biological subtypes

The aim of this study was to divide the group of triple-negative breast cancer patients with brain metastases into basal-like and non-basal-like biological subtypes in order to compare clinical features and survival rates in those two groups. A comprehensive analysis of 111 consecutive triple-negative breast cancer patients with brain metastases treated in the years 2003–2009 was performed. In 75 patients, immunohistochemistry was used as a surrogate of microarray in order to evaluate the expression of three basal markers: cytokeratin 5/6 (CK 5/6), EGFR/HER1 and c-KIT. The basal-like (ER/PgR/HER2-negative, CK5/6positive and/or HER1-positive) and non-basal-like (ER/PgR/HER2-negative, CK5/6-negative, HER1-negative) subsets were selected. Clinical features and survivals were compared in both groups. In the group of 111 triple-negative breast cancer patients, median DFS, OS and survival from brain metastases were 20, 29 and 4 months, respectively. In 75 patients who were evaluable for basal markers, median DFS, OS and survival from brain metastases were 18, 26 and 3.2 months, respectively. In the basal-like subtype, the survival rates were 15, 26 and 3 months, respectively, and in the non-basal-like subtypes, they were 20, 30 and 2.8 months, respectively. No statistically significant differences in survivals were detected between the basal-like and non-basal-like biological subtypes. Factors influencing survival from brain metastases were: Karnofsky performance status (KPS), the status of extracranial disease and age. Biological markers differentiating triple-negative group into basal-like and non-basal-like subtype (CK 5/6, HER1, c-KIT) had no influence on survival. In patients with triple-negative breast cancer and brain metastases, well-known clinical, but not molecular, features correlated with survival.

Antitumor activity of Noscapine in combination with Doxorubicin in triple negative breast cancer

Background

The aim of this study was to investigate the anticancer activity and mechanism of action of Noscapine alone and in combination with Doxorubicin against triple negative breast cancer (TNBC).

Methods

TNBC cells were pretreated with Noscapine or Doxorubicin or combination and combination index values were calculated using isobolographic method. Apoptosis was assessed by TUNEL staining. Female athymic Nu/nu mice were xenografted with MDA-MB-231 cells and the efficacy of Noscapine, Doxorubicin and combination was determined. Protein expression, immunohistochemical staining were evaluated in harvested tumor tissues.

Results

Noscapine inhibited growth of MDA-MB-231 and MDA-MB-468 cells with the IC₅₀ values of 36.16±3.76 and 42.7±4.3 µM respectively. The CI values (<0.59) were suggestive of strong synergistic interaction between Noscapine and Doxorubicin and combination treatment showed significant increase in apoptotic cells. Noscapine showed dose dependent reduction in the tumor volumes at a dose of 150–550 mg/kg/day compared to controls. Noscapine (300 mg/kg), Doxorubicin (1.5 mg/kg) and combination treatment reduced tumor volume by 39.4±5.8, 34.2±5.7 and 82.9±4.5 percent respectively and showed decreased expression of NF-KB pathway proteins, VEGF, cell survival, and increased expression of apoptotic and growth inhibitory proteins compared to single-agent treatment and control groups.

Conclusions

Noscapine potentiated the anticancer activity of Doxorubicin in a synergistic manner against TNBC tumors via inactivation of NF-KB and anti-angiogenic pathways while stimulating apoptosis. These findings suggest potential benefit for use of oral Noscapine and Doxorubicin combination therapy for treatment of more aggressive TNBC.

Targeting tumour-initiating cells to improve the cure rates for triple-negative breast cancer

Tumour recurrence is one of the biggest challenges in breast cancer management because it affects 25-30% of women with breast cancer and the tumours are often incurable. Women with triple-negative breast cancer (TNBC--lacking expression of the oestrogen receptor, progesterone receptor and the receptor HER2/ERBB2) have the highest rates of early recurrence relative to other breast cancer subtypes. Early recurrence might be due to tumour-initiating cells (TICs), which are resistant to conventional therapies, can remain dormant and can subsequently give rise to secondary tumours. In breast cancer, TICs are identified by the cell-surface markers CD44+/CD24-/EpCAM+ and/or possess ALDH1 enzyme activity. This subpopulation has the ability to self-renew, grow as mammospheres and initiate tumour formation. Fuelling the problem of relapse is the fact that chemotherapy and radiation can induce or select for TICs; this was reported in preclinical models and more recently in women being treated for breast cancer. Thus, new therapeutic agents for TNBC are presently being sought to overcome this problem. Here we review the roles of receptor tyrosine kinases, signalling intermediates and transcription factors in sustaining the TIC subpopulation. Particular emphasis is placed on targeting these molecules in order to eliminate and/or prevent the induction of TICs and ultimately reduce the frequency of TNBC recurrence.

Clinicopathological features and treatment strategy for triple-negative breast cancer

Breast cancers are divided into at least 4 subtypes on the basis of gene expression profiles and expression of receptors (hormone receptors (HR) and HER2) as measured by immunohistochemistry. These subtypes have different prognoses and responses to treatments such as endocrine manipulation, anti-HER2 therapy, and chemotherapy. Triple-negative breast cancer (TNBC) is immunohistochemically defined as lacking estrogen and progesterone receptors and not overexpressing HER2. TNBC accounts for approximately 15% of breast cancer patients, and is more chemosensitive but has a worse prognosis than the HR-positive/HER2-negative phenotype. TNBC is a heterogeneous disease that does not offer specific targets in the same way as HR-positive and HER2-positive breast cancers, and is similar to basal-like breast cancer and BRCA1-related breast cancer. At present, the lack of highly effective therapeutic targets for TNBC leaves standard chemotherapy, for example the combination of anthracycline and taxane, as the only medical treatment, but this is insufficiently efficacious. Novel approaches for TNBC, for example DNA damaging agents, PARP-1 inhibitors, receptor tyrosin kinase inhibitors (TKIs), and antiangiogenesis agents, have been examined in clinical settings. Concerning therapeutic strategies for TNBC, it is most important to develop novel effective approaches for TNBC treatment and high-throughput predictive tools for standard chemotherapy and novel agents.

Triple-negative breast cancer: present challenges and new perspectives

Triple-negative breast cancers (TNBC), characterized by absence of estrogen receptor (ER), progesterone receptor (PR) and lack of overexpression of human epidermal growth factor receptor 2 (HER2), are typically associated with poor prognosis, due to aggressive tumor phenotype(s), only partial response to chemotherapy and present lack of clinically established targeted therapies. Advances in the design of individualized strategies for treatment of TNBC patients require further elucidation, by combined 'omics' approaches, of the molecular mechanisms underlying TNBC phenotypic heterogeneity, and the still poorly understood association of TNBC with BRCA1 mutations. An overview is here presented on TNBC profiling in terms of expression signatures, within the functional genomic breast tumor classification, and ongoing efforts toward identification of new therapy targets and bioimaging markers. Due to the complexity of aberrant molecular patterns involved in expression, pathological progression and biological/clinical heterogeneity, the search for novel TNBC biomarkers and therapy targets requires collection of multi-dimensional data sets, use of robust multivariate data analysis techniques and development of innovative systems biology approaches.

The role of MAP kinases and MAP kinase phosphatase-1 in resistance to breast cancer treatment

Chemotherapy resistance is an important problem often encountered during the course of breast cancer treatment. In order to design rational and efficacious therapies, the molecular mechanisms used by cells to develop resistance must be investigated. One mechanism employed by cancer cells is to alter cell signaling. This review examines the role of mitogen-activated protein kinases (MAPKs) and their endogenous negative regulators, mitogen-activated protein kinase phosphatases (MKPs), in chemotherapy resistance in breast cancer. MAPK signaling is activated in response to both growth factors and cellular stress. MKPs dephosphorylate MAPKs and are part of the dual-specificity family of phosphatases. MAPKs have been shown to be involved in resistance to tamoxifen, and MKPs have been linked to resistance to treatment with doxorubicin, mechlorethamine, paclitaxel, proteasome inhibitors, and oxidative-stress-induced cell death in breast cancer. The role of MKPs in tamoxifen resistance and the elucidation of the mechanisms involved with resistance to standard chemotherapy agents need to be investigated further. Growing evidence suggests that modulating MKP-1 activity could be a viable option to make breast cancer chemotherapy more effective.

Treating triple-negative breast cancer by a combination of rapamycin and cyclophosphamide: an in vivo bioluminescence imaging study

Rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, has been shown to inhibit the growth of oestrogen positive breast cancer. However, triple-negative (TN) breast cancer is resistant to rapamycin treatment in vitro. We set to test a combination treatment of rapamycin with DNA-damage agent, cyclophosphamide, in a TN breast cancer model. By binding to and disrupting cellular DNA, cyclophosphamide kills cells via interfering with their normal functions. We assessed the responses of nude mice bearing tumour xenografts of TN MDA-MB-231 cells to the combination of rapamycin and cyclophosphamide in both orthotopic mammary and lung-metastasis models. We tracked tumour growth and metastasis by bioluminescent imaging and examined the expression of Ki67, CD34 and HIF-1alpha in tumour tissues by immunohistochemistry and apoptosis index with TUNEL assay, and found that MDA-MB-231 cells are sensitive to rapamycin therapy in orthotopic mammary, but not in lung with metastasis. Rapamycin when combined with cyclophosphamide is found to have a more significant effect in reducing tumour volume and metastasis with a much improved survival rate. Our data also show that the sensitivity of TN tumours to rapamycin is associated with the microenvironment of the tumour cells. The data indicate that in a relatively hypoxic environment HIF-1alpha may play a role in mediating the anti-cancer effect of rapamycin and cyclophosphamide may prevent the feedback activation of Akt by rapamycin. Overall our results show that rapamycin plus cyclophosphamide can achieve an improved efficacy in suppressing tumour growth and metastasis, suggesting that the combination therapy can be a promising treatment option for TN cancer.