New protein kinase inhibitors in breast cancer: afatinib and neratinib

Application of SNAP-tag-EGFR cell membrane chromatography model in screening antitumor active components of Silybum marianum (L.) Gaertn

The SNAP-tag-epidermal growth factor receptor (SNAP-tag-EGFR) cell membrane chromatography (CMC) model is a powerful tool for investigating ligand-receptor interactions and screening active ingredients in traditional Chinese medicine. Most tyrosine kinase inhibitors (TKIs) target epidermal growth factor receptors. However, TKIs associated with significant side effects and drug resistance must be addressed immediately. Therefore, there is an urgent need to develop new TKIs with high efficiency and low toxicity. Because of its low toxicity and side effects, traditional Chinese medicine has been widely employed to treat various diseases, including cancer. Hence, this study aimed to use the SNAP-tag-EGFR/CMC-high-performance liquid chromatography-mass spectrometry (HPLC-MS) two-dimensional system model as the research tool to screen and identify potential EGFR antagonists from the Chinese medicine Silybum marianum (L.) Gaertn. The applicability of the system was verified using the positive control drug osimertinib. Four potential EGFR antagonists were screened from the Chinese medicine Silybum marianum (L.) Gaertn.. They were identified as silydianin, silychristin, silybin, and isosilybin. Additionally, their pharmacological activity was preliminarily verified using a CCK-8 assay. The kinetic parameters of the four active ingredients interacting with EGFR and their binding modes with EGFR were analyzed using nonlinear chromatography (NLC) and molecular docking. This study identified silydianin, silychristin, silybin, and isosilybin from Silybum marianum (L.) Gaertn. and verified their potential antitumor effects on EGFR.

Therapeutic Landscape of Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer

Human epidermal growth factor receptor 2-positive breast cancer (HER2+BC) is a common malignancy that is prone to recurrence and metastasis in the early stages, resulting in a poor prognosis for patients. Many studies have suggested that targeted therapy promotes clinical outcomes in HER2+BC. With the introduction of trastuzumab in 1998, the prognosis of patients with early HER2+BC has improved significantly. However, owing to obstinate drug resistance and adverse events, the addition of new agents in standardized treatment has become a research hotspot. These promising agents include antibodies, antibody-drug conjugates, tyrosine kinase inhibitors, and anti-HER2 combined therapies. This article provides a brief description of the biology of BC and the expression of HER2, with the aim to provide an overview of the therapeutic landscape of HER2+BC by reviewing research results and introducing the latest evidence to provide a reference for clinical treatment.

HER4 expression in estrogen receptor-positive breast cancer is associated with decreased sensitivity to tamoxifen treatment and reduced overall survival of postmenopausal women

BACKGROUND

The sensitivity of estrogen receptor-positive breast cancers to tamoxifen treatment varies considerably, and the molecular mechanisms affecting the response rates are manifold. The human epidermal growth factor receptor-related receptor HER2 is known to trigger intracellular signaling cascades that modulate the activity of coregulators of the estrogen receptor which, in turn, reduces the cell sensitivity to tamoxifen treatment. However, the impact of HER2-related receptor tyrosine kinases HER1, HER3, and, in particular, HER4 on endocrine treatment is largely unknown.

METHODS

Here, we retrospectively evaluated the importance of HER4 expression on the outcome of tamoxifen- and aromatase inhibitor-treated estrogen receptor-positive breast cancer patients (n = 258). In addition, we experimentally analyzed the efficiency of tamoxifen treatment as a function of HER4 co-expression in vitro.

RESULTS

We found a significantly improved survival in tamoxifen-treated postmenopausal breast cancer patients in the absence of HER4 compared with those with pronounced HER4 expression. In accordance with this finding, the sensitivity to tamoxifen treatment of estrogen and HER4 receptor-positive ZR-75-1 breast cancer cells can be significantly enhanced by HER4 knockdown.

CONCLUSION

We suggest an HER4/estrogen receptor interaction that impedes tamoxifen binding to the estrogen receptor and reduces treatment efficiency. Whether the sensitivity to tamoxifen treatment can be enhanced by anti-HER4 targeting needs to be prospectively evaluated.

Metastatic and triple-negative breast cancer: challenges and treatment options

The major current conventional types of metastatic breast cancer (MBC) treatments include surgery, radiation, hormonal therapy, chemotherapy, or immunotherapy. Introducing biological drugs, targeted treatment and gene therapy can potentially reduce the mortality and improve the quality of life in patients with MBC. However, combination of several types of treatment is usually recommended. Triple negative breast cancer (TNBC) accounts for 10-20% of all cases of breast carcinoma and is characterized by the low expression of progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2). Consequently, convenient treatments used for MBC that target these receptors are not effective for TNBC which therefore requires special treatment approaches. This review discusses the occurrence of MBC, the prognosis and predictive biomarkers of MBC, and focuses on the novel advanced tactics for treatment of MBC and TNBC. Nanotechnology-based combinatorial approach for the suppression of EGFR by siRNA and gifitinib is described.

Knockdown of PAICS inhibits malignant proliferation of human breast cancer cell lines

BACKGROUND

Phosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), an enzyme required for de novo purine biosynthesis, is associated with and involved in tumorigenesis. This study aimed to evaluate the role of PAICS in human breast cancer, which remains the most frequently diagnosed cancer and the leading cause of cancer-related death among women in less developed countries.

RESULTS

Lentivirus-based short hairpin RNA targeting PAICS specifically depleted its endogenous expression in ZR-75-30 and MDA-MB-231 breast cancer cells. Depletion of PAICS led to a significant decrease in cell viability and proliferation. To ascertain the mechanisms through which PAICS modulates cell proliferation, flow cytometry was performed, and it was confirmed that G1-S transition was blocked in ZR-75-30 cells through PAICS knockdown. This might have occurred partly through the suppression of Cyclin E and the upregulation of Cyclin D1, P21, and CDK4. Moreover, PAICS knockdown obviously promoted cell apoptosis in ZR-75-30 cells through the activation of PARP and caspase 3 and downregulation of Bcl-2 and Bcl-xl expression in ZR-75-30 cells.

CONCLUSIONS

These findings demonstrate that PAICS plays an essential role in breast cancer proliferation in vitro, which provides a new opportunity for discovering and identifying novel effective treatment strategies.

Antibody-assisted target identification reveals afatinib, an EGFR covalent inhibitor, down-regulating ribonucleotide reductase

Afatinib, used for the first-line treatment of non-small-cell lung carcinoma (NSCLC) patients with distinct epidermal growth factor receptor (EGFR) mutations, inactivates EGFR by mimicking ATP structure and forming a covalent adduct with EGFR. We developed a method to unravel potential targets of afatinib in NSCLC cells through immunoprecipitation of afatinib-labeling proteins with anti-afatinib antiserum and mass spectrometry analysis. Ribonucleotide reductase (RNR) is one of target proteins of afatinib revealed by this method. Treatment of afatinib at 10-100 nM potently inhibited intracellular RNR activity in an in vitro assay using permeabilized PC-9 cells (formerly known as PC-14). PC-9 cells treated with 10 μM afatinib displayed elevated markers of DNA damage. Long-term treatment of therapeutic concentrations of afatinib in PC-9 cells caused significant decrease in protein levels of RNR subunit M2 at 1-10 nM and RNR subunit M1 at 100 nM. EGFR-null Chinese hamster ovary (CHO) cells treated with afatinib also showed similar effects. Afatinib repressed the upregulation of RNR subunit M2 induced by gemcitabine. Covalent modification with afatinib resulting in inhibition and protein downregulation of RNR underscores the therapeutic and off-target effects of afatinib. Afatinib may serve as a lead compound of chemotherapeutic drugs targeting RNR. This method can be widely used in the identification of potential targets of other covalent drugs.

Protein Kinase Targets in Breast Cancer

With 1.67 million new cases and 522,000 deaths in the year 2012, breast cancer is the most common type of diagnosed malignancy and the second leading cause of cancer death in women around the world. Despite the success of screening programs and the development of adjuvant therapies, a significant percentage of breast cancer patients will suffer a metastatic disease that, to this day, remains incurable and justifies the research of new therapies to improve their life expectancy. Among the new therapies that have been developed in recent years, the emergence of targeted therapies has been a milestone in the fight against cancer. Over the past decade, many studies have shown a causal role of protein kinase dysregulations or mutations in different human diseases, including cancer. Along these lines, cancer research has demonstrated a key role of many protein kinases during human tumorigenesis and cancer progression, turning these molecules into valid candidates for new targeted therapies. The subsequent discovery and introduction in 2001 of the kinase inhibitor imatinib, as a targeted treatment for chronic myelogenous leukemia, revolutionized cancer genetic pathways research, and lead to the development of multiple small-molecule kinase inhibitors against various malignancies, including breast cancer. In this review, we analyze studies published to date about novel small-molecule kinase inhibitors and evaluate if they would be useful to develop new treatment strategies for breast cancer patients.

Breast cancer treatment-induced cardiotoxicity

INTRODUCTION

Breast cancer is the most frequent cancer affecting women worldwide. In every setting, the majority of women are treated with an evergrowing arsenal of therapeutic agents that have greatly improved their outcomes. However, these therapies can also be associated with significant adverse events. Areas covered: This review aims to thoroughly describe the current state of the evidence regarding the potential cardiotoxicity of agents commonly used in the treatment of breast cancer. These include chemotherapeutic agents, anti-HER2 therapies and CDK4/6 and mTOR inhibitors. Furthermore, issues related to the risk stratification and monitoring tools are explored. Expert opinion: Anthracycline- and trastuzumab-related cardiac toxicities have been extensively studied. Substantial evidence is now available concerning additional anti-HER2 agents such as pertuzumab, T-DM1 and tyrosine kinase inhibitors; overall, the cardiotoxicity profile is reassuring. Cardiac events due to endocrine therapy are mostly ischemic and, in the context of prolonged therapy, need specific attention. Novel agents implicated in the treatment of hormone receptor-positive disease are potentially arrhythmogenic and the exact risk will need to be further refined. As for today, assessment of baseline risk factors prior to treatment initiation and cardiac imaging before and during treatment remains the optimal way to prevent cardiac dysfunction. Cardioprotective therapy in primary prevention is still a matter of debate.

Emerging treatments for HER2-positive early-stage breast cancer: focus on neratinib

Over the last decades, a better understanding of breast cancer heterogeneity provided tools for a biologically based personalization of anticancer treatments. In particular, the overexpression of the human epidermal growth factor receptor 2 (HER2) by tumor cells provided a specific target in these HER2-positive tumors. The development of the monoclonal antibody trastuzumab, and its approval in 1998 for the treatment of patients with metastatic disease, radically changed the natural history of this aggressive subtype of breast cancer. These findings provided strong support for the continuous research in targeting the HER2 pathway and implementing the development of new anti-HER2 targeted agents. Besides trastuzumab, a series of other anti-HER2 agents have been developed and are currently being explored for the treatment of breast cancer patients, including those diagnosed with early-stage disease. Among these agents, neratinib, an oral tyrosine kinase inhibitor that irreversibly inhibits HER1, HER2, and HER4 at the intracellular level, has shown promising results, including when administered to patients previously exposed to trastuzumab-based treatment. This article aims to review the available data on the role of the HER2 pathway in breast cancer and on the different targeted agents that have been studied or are currently under development for the treatment of patients with early-stage HER2-positive disease with a particular focus on neratinib.

Antibiofilm activity and mode of action of DMSO alone and its combination with afatinib against Gram-negative pathogens

Biofilms are complex microbial communities that tend to attach to either biotic or abiotic surface. Enclosed in a self-produced extracellular polymeric substance (EPS) matrix, the biofilms often cause persistent infections. The objective of this study was to investigate the antibiofilm activity of dimethyl sulfoxide (DMSO) and afatinib against Gram-negative pathogens. Test microorganisms used in this study were Escherichia coli ATCC 1299, Pseudomonas aeruginosa ATCC 10145, and Salmonella typhimurium ATCC 14028. Biofilms were developed in 96-well microplate at 37°C for 24 h. Following removal of non-adherent cells, analysis of biofilm viability, biofilm biomass, and extracellular polymeric substances (EPS) matrix were performed using resazurin assay, crystal violet assay, and attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Bradford protein assay was conducted to determine the total amount of EPS proteins. The results demonstrated that both 32% DMSO alone and its combination with 3.2 μg/mL afatinib were effective in killing biofilm cells and reducing biofilm biomass. IR spectral variations of EPS matrix of biofilms in the range between 1700 and 900 cm^-1 were also observed. Reduction in EPS proteins verified the chemical modifications of EPS matrix. In conclusion, 32% DMSO alone and its combination with 3.2 μg/mL afatinib showed remarkable antibiofilm activities against Gram-negative pathogens. It was suggested that the biofilm inhibition was mediated by the chemical modification of EPS matrix.

Advances in systemic therapy for metastatic breast cancer: future perspectives

Breast cancer (BC) is the most common cancer in women worldwide. One in eight women will develop the disease in her lifetime. Notwithstanding the incredible progress made in this field, BC still represents the second most common cause of cancer-related death in women. Targeted drugs have revolutionised breast cancer treatment and improved the prognosis as well as the life expectancy of millions of women. However, the phenomenon of primary and secondary pharmacological resistance is becoming increasingly evident, limiting the efficacy of these agents and calling for a better in-depth knowledge and understanding of the biology as well as the biochemical crosstalk underlying the disease. The advent of laboratory technologies in the clinical setting such as the routine use of next generation sequencing has allowed identification of new genetic alterations as well as providing a precise picture of the molecular landscapes of each tumour. Consequently, new specific therapeutic approaches are becoming available to minimise or delay the occurrence of resistance. In this review, we analyse the latest research and news from the clinical development side for each BC subtype.

Management of breast cancer brain metastases: Focus on human epidermal growth factor receptor 2-positive breast cancer

After the introduction of trastuzumab, a monoclonal antibody that binds to human epidermal growth factor receptor 2 (HER2), the overall survival (OS) among patients with HER2-positive breast cancer has been substantially improved. However, among these patients, the incidence of brain metastases (BM) has been increasing and an increased proportion of them have died of intracranial progression, which makes HER2-positive breast cancer brain metastases (BCBM) a critical issue of concern. For local control of limited BM, stereotactic radiosurgery (SRS) and surgical resection are available modalities with different clinical indications. Postoperative or preoperative radiation is usually delivered in conjunction with surgical resection to boost local control. Adjuvant whole-brain radiotherapy (WBRT) should be deferred for limited BM because of its impairment of neurocognitive function while having no benefit for OS. Although WBRT is still the standard treatment for local control of diffuse BM, SRS is a promising treatment for diffuse BM as the technique continues to improve. Although large molecules have difficulty crossing the blood brain barrier, trastuzumab-containing regimens are critical for treating HER2-positive BCBM patients because they significantly prolong OS. Tyrosine kinase inhibitors are more capable of crossing into the brain and they have been shown to be beneficial for treating BM in HER2-positive patients, especially lapatinib combined with capecitabine. The antiangiogenic agent, bevacizumab, can be applied in the HER2-positive BCBM scenario as well. In this review, we also discuss several strategies for delivering drugs into the central nervous system and several microRNAs that have the potential to become biomarkers of BCBM.

Adjuvant trastuzumab: a 10-year overview of its benefit

INTRODUCTION

Anti-HER2 targeted therapy is one of the key advances in the treatment of breast cancer that have occurred in the last 20 years. In the adjuvant setting, the use of trastuzumab has led to prolonged and sustained survival benefit with very little toxicity as also confirmed by the 10-year follow-up results from the pivotal trials. Despite the survival improvement, several key issues are not entirely resolved in this field. These issues have led to multiple research efforts in de-escalating or escalating the standard treatment with chemotherapy and 1 year of adjuvant trastuzumab. Areas covered: In this paper, we present an in depth overview on the state of the art on these key issues of refining decision-making in adjuvant anti-HER2 therapy. Expert commentary: Despite many important research efforts in the field, chemotherapy plus trastuzumab for a total duration of 1 year remains the standard of care. However, recent data showed that besides standard anthracycline- and taxane-based cytotoxic therapy, alternative chemotherapy regimens can now be proposed to patients with small tumors without nodal involvement and to women at high-risk of developing cardiotoxicity. Of note, besides HER2 itself, biomarkers predicting patients who may truly benefit from anti-HER2 agents are still lacking.

Twenty years of anti-HER2 therapy-associated cardiotoxicity

Over the past 20 years, the prognosis of HER2-positive breast cancer has been transformed by the development of anti-HER2 targeted therapies. In early clinical trials of trastuzumab (ie, the first anti-HER2 agent to be developed) cardiotoxicity became a major concern. In the first published phase 3 trial of trastuzumab, 27% of patients receiving anthracyclines and trastuzumab experienced cardiac events and 16% suffered from severe congestive heart failure. In subsequent trials conducted in advanced and early settings, the incidence of cardiac events was reduced through changes in chemotherapy regimens, more strict patient selection and close cardiac assessment. However, cardiotoxicity remains a significant problem in clinical practice that is likely to increase as new agents are approved and exposure times increase through improved patients' survival. Though numerous trials have led to improved understanding of many aspects of anti-HER2 therapy-related cardiotoxicity, its underlying physiopathology mechanisms are not well understood. The purpose of this article is to provide an in-depth review on anti-HER2 therapy-related cardiotoxicity, including data on both trastuzumab and the recently developed anti-HER2 targeted agents.

Targeting EGF-receptor(s) - STAT1 axis attenuates tumor growth and metastasis through downregulation of MUC4 mucin in human pancreatic cancer

Transmembrane proteins MUC4, EGFR and HER2 are shown to be critical in invasion and metastasis of pancreatic cancer. Besides, we and others have demonstrated de novo expression of MUC4 in ~70-90% of pancreatic cancer patients and its stabilizing effects on HER2 downstream signaling in pancreatic cancer. Here, we found that use of canertinib or afatinib resulted in reduction of MUC4 and abrogation of in vitro and in vivo oncogenic functions of MUC4 in pancreatic cancer cells. Notably, silencing of EGFR family member in pancreatic cancer cells decreased MUC4 expression through reduced phospho-STAT1. Furthermore, canertinib and afatinib treatment also inhibited proliferation, migration and survival of pancreatic cancer cells by attenuation of signaling events including pERK1/2 (T202/Y204), cyclin D1, cyclin A, pFAK (Y925) and pAKT (Ser473). Using in vivo bioluminescent imaging, we demonstrated that canertinib treatment significantly reduced tumor burden (P=0.0164) and metastasis to various organs. Further, reduced expression of MUC4 and EGFR family members were confirmed in xenografts. Our results for the first time demonstrated the targeting of EGFR family members along with MUC4 by using pan-EGFR inhibitors. In conclusion, our studies will enhance the translational acquaintance of pan-EGFR inhibitors for combinational therapies to combat against lethal pancreatic cancer.

Targeted Therapy in Brain Metastases: Ready for Primetime?

Brain metastasis is a serious complication of cancer that causes significant morbidity for patients. Over the last decade, numerous new driver somatic mutations have been recognized and targeted therapies are changing the landscape of treatment in lung cancer, breast cancer, and melanoma, which are also the three most common cancers that result in brain metastases. The common actionable mutations include the EGFR mutation and anaplastic lymphoma kinase (ALK) translocations in non-small cell lung cancer, the HER2 mutation in breast cancer, and the BRAF mutation in melanoma. However, most of the early trials with targeted agents excluded patients with brain metastases. With a better understanding of the biology, several recent trials of targeted therapy that focus on brain metastases have been reported and others are ongoing. Novel agents with better penetration across the blood-brain barrier are currently being investigated for patients with brain metastases. In this review, we discuss the current state of use and future directions of targeted therapies in brain metastases.

Theoretical and Experimental Investigation of Thermodynamics and Kinetics of Thiol-Michael Addition Reactions: A Case Study of Reversible Fluorescent Probes for Glutathione Imaging in Single Cells

Density functional theory (DFT) was applied to study the thermodynamics and kinetics of reversible thiol-Michael addition reactions. M06-2X/6-31G(d) with the SMD solvation model can reliably predict the Gibbs free energy changes (ΔG) of thiol-Michael addition reactions with an error of less than 1 kcal·mol(-1) compared with the experimental benchmarks. Taking advantage of this computational model, the first reversible reaction-based fluorescent probe was developed that can monitor the changes in glutathione levels in single living cells.

Targeting HER2 for the treatment of breast cancer

HER2 (ErbB2), a member of the HER family of tyrosine kinase receptors (HER1-4), is a major driver of tumor growth in 20% of breast cancers. Treatment with the anti-HER2 monoclonal antibody trastuzumab has revolutionized the outcome of patients with this aggressive breast cancer subtype, but intrinsic and acquired resistance is common. Growing understanding of the biology and complexity of the HER2 signaling network and of potential resistance mechanisms has guided the development of new HER2-targeted agents. Combinations of these drugs to more completely inhibit the HER receptor layer, or combining HER2-targeted agents with agents that target downstream signaling, alternative pathways, or components of the host immune system, are being vigorously investigated in the preclinical and clinical settings. As a result, the list of more effective and well tolerated FDA-approved new regimens for patients with HER2+ tumors is constantly growing.

The epidermal growth factor receptor (EGFR / HER-1) gatekeeper mutation T790M is present in European patients with early breast cancer

The epidermal growth factor receptor (EGFR) is one of the major oncogenes identified in a variety of human malignancies including breast cancer (BC). EGFR-mutations have been studied in lung cancer for some years and are established as important markers in guiding therapy with tyrosine kinase inhibitors (TKIs). In contrast, EGFR-mutations have been reported to be rare if not absent in human BC, although recent evidence has suggested a significant worldwide variation in somatic EGFR-mutations. Therefore, we investigated the presence of EGFR-mutations in 131 norwegian patients diagnosed with early breast cancer using real-time PCR methods. In the present study we identified three patients with an EGFR-T790M-mutation. The PCR-findings were confirmed by direct Sanger sequencing. Two patients had triple-negative BC (TNBC) while the third was classified as luminal-A subtype. The difference in incidence of T790M mutations comparing the TNBC subgroup with the other BC subgroups was statistical significant (P = 0.023). No other EGFR mutations were identified in the entire cohort. Interestingly, none of the patients had received any previous cancer treatment. To our best knowledge, the EGFR-T790M-TKI-resistance mutation has not been previously detected in breast cancer patients. Our findings contrast with the observations made in lung cancer patients where the EGFR-T790M-mutation is classified as a typical „second mutation”causing resistance to TKI-therapy during ongoing anticancer therapy. In conclusion, we have demonstrated for the first time that the EGFR-T790M-mutation occurs in primary human breast cancer patients. In the present study the EGFR-T790M mutation was not accompanied by any simultaneous EGFR-activating mutation.

Label-free LC-MS analysis of HER2+ breast cancer cell line response to HER2 inhibitor treatment

BACKGROUND

Human epidermal growth-factor receptor (HER)-2 is overexpressed in 25 % of breast-cancers and is associated with an aggressive form of the disease with significantly shortened disease free and overall survival. In recent years, the use of HER2-targeted therapies, monoclonal-antibodies and small molecule tyrosine-kinase inhibitors has significantly improved the clinical outcome for HER2-positive breast-cancer patients. However, only a fraction of HER2-amplified patients will respond to therapy and the use of these treatments is often limited by tumour drug insensitivity or resistance and drug toxicities. Currently there is no way to identify likely responders or rational combinations with the potential to improve HER2-focussed treatment outcome.

METHODS

In order to further understand the molecular mechanisms of treatment-response with HER2-inhibitors, we used a highly-optimised and reproducible quantitative label-free LC-MS strategy to characterize the proteomes of HER2-overexpressing breast-cancer cell-lines (SKBR3, BT474 and HCC1954) in response to drug-treatment with HER2-inhibitors (lapatinib, neratinib or afatinib).

RESULTS

Following 12 ours treatment with different HER2-inhibitors in the BT474 cell-line; compared to the untreated cells, 16 proteins changed significantly in abundance following lapatinib treatment (1 μM), 21 proteins changed significantly following neratinib treatment (150 nM) and 38 proteins changed significantly following afatinib treatment (150 nM). Whereas following 24 hours treatment with neratinib (200 nM) 46 proteins changed significantly in abundance in the HCC1954 cell-line and 23 proteins in the SKBR3 cell-line compared to the untreated cells. Analysing the data we found that, proteins like trifunctional-enzyme subunit-alpha, mitochondrial; heterogeneous nuclear ribonucleoprotein-R and lamina-associated polypeptide 2, isoform alpha were up-regulated whereas heat shock cognate 71 kDa protein was down-regulated in 3 or more comparisons.

CONCLUSION

This proteomic study highlights several proteins that are closely associated with early HER2-inhibitor response and will provide a valuable resource for further investigation of ways to improve efficacy of breast-cancer treatment.

Overexpression of neogenin inhibits cell proliferation and induces apoptosis in human MDA-MB-231 breast carcinoma cells

Neogenin has been documented as playing an important role in cancer development. Although an elevated expression of neogenin has been detected in human breast cancer, the role of neogenin in breast cancer cells is not clearly understood. In the present study, we investigated neogenin in breast cancer cell proliferation, migration and apoptosis. We found that neogenin overexpression markedly reduced the proliferation and migration of breast cancer cells (P<0.05). Neogenin overexpression resulted in a reduction in the apoptosis rate. Inhibition of neogenin expression by neogenin siRNA dramatically promoted the proliferation and migration of breast cancer cells, whereas it inhibited cell apoptosis. Furthermore, we found that BMP-2-induced phosphorylation of Smad1/5/8 which was inhibited by neogenin overexpression. The present study demonstrates that neogenin may be a tumor suppressor in breast cancer. Neogenin may serve as a potential diagnostic marker and therapeutic target for breast cancer.

Effect of cycloxygenase-2 silencing on the malignant biological behavior of MCF-7 breast cancer cells

The aim of the present study was to investigate the effect of cyclooxygenase-2 (COX-2) silencing on the malignant biological behavior of MCF-7 breast cancer cells. COX-2 short hairpin RNA (shRNA) and unassociated sequences were synthesized and a shRNA lentiviral vector was constructed. The vector was transfected into MCF-7 breast cancer cells, in which clones with stable expression were screened out. The expression of COX-2 mRNA and protein was silenced using RNA interference (RNAi). Quantitative polymerase chain reaction, western blotting, a mononuclear cell direct cytotoxicity assay (MTT assay), a cell invasion assay and scratch tests were performed to investigate the downregulation of COX-2 mRNA and protein expression, the proliferative activity and growth rate of MCF-7 breast cancer cells, the glioblastoma multiforme (GBM) penetrating capacity, the cell movement and migratory capacity, and vascular endothelial growth factor (VEGF)-A and VEGF-C protein expression. The results revealed that the sequence-specific shRNA significantly downregulated the expression of COX-2 at the mRNA and protein levels. Furthermore, the downregulation of COX-2 expression markedly decreased the invasive and metastatic capacities of the cells, suppressed the proliferation, decreased the rate of growth, decreased the capacity of GBM penetration and migration, and decreased the protein expression of VEGF-A and VEGF-C, the two key factors that regulate tumor angiogenesis and lymphangiogenesis. In conclusion, the RNAi technique effectively silenced COX-2 gene expression and inhibited MCF-7 breast cancer cell proliferation, invasion and metastasis by decreasing VEGF-A and VEGF-C expression, which regulates tumor angiogenesis and lymphangiogenesis. Therefore, an RNAi technique that targets COX-2 presents a promising prospect for breast cancer gene therapy.