Role of HER2/HER3 co-receptor in breast carcinogenesis

Mammalian orthoreovirus infection in human epidermal growth factor receptor 2 positive (HER2+) breast cancer cells

Mammalian orthoreovirus (MRV) is a clinically benign oncolytic virus which has been investigated for use in multiple cancer types, including breast cancer (BC). In human clinical trials, MRV has been shown to be safe, and multiple BC patients have shown partial responses to intratumoral and intravenous virus delivery. Combination therapies inclusive of MRV and current FDA approved BC chemotherapies are being investigated to target metastatic, early BC, and triple negative BC. Though MRV is being tested clinically, we still do not fully understand the highly variable patient responses to MRV therapy. One of the most aggressive BC subtypes is HER2+ BC, in which human epidermal growth factor receptor 2 (HER2) is dysregulated, resulting in increased growth, survival, and metastasis of cancer cells. FDA approved therapies, trastuzumab and pertuzumab, target HER2 to prevent signaling of the phosphoinositide 3-kinase (PI3K) pathway. However, recent findings show that accumulation of hypoxia inducible factor-1 alpha (HIF-1α) in HER2+ BC cells contributes to trastuzumab resistance. In this work, we provide evidence that MRV infects, replicates in, and kills HER2 overexpressing cells. MRV infection is also found to have variable effects on signaling pathways that activate or are activated by HER2 expression. Finally, we show that MRV reduces HIF-1α accumulation in all the cell lines tested, including a HER2+ BC cell line. These studies provide further evidence that MRV holds promise for use in conjunction with trastuzumab to treat HER2+ BC patients.

ErbB3-Targeting Oncolytic Adenovirus Causes Potent Tumor Suppression by Induction of Apoptosis in Cancer Cells

Cancer is a multifactorial and deadly disease. Despite major advancements in cancer therapy in the last two decades, cancer incidence is on the rise and disease prognosis still remains poor. Furthermore, molecular mechanisms of cancer invasiveness, metastasis, and drug resistance remain largely elusive. Targeted cancer therapy involving the silencing of specific cancer-enriched proteins by small interfering RNA (siRNA) offers a powerful tool. However, its application in clinic is limited by the short half-life of siRNA and warrants the development of efficient and stable siRNA delivery systems. Oncolytic adenovirus-mediated therapy offers an attractive alternative to the chemical drugs that often suffer from innate and acquired drug resistance. In continuation to our reports on the development of oncolytic adenovirus-mediated delivery of shRNA, we report here the replication-incompetent (dAd/shErbB3) and replication-competent (oAd/shErbB3) oncolytic adenovirus systems that caused efficient and persistent targeting of ErbB3. We demonstrate that the E1A coded by oAd/shErbB, in contrast to dAd/shErbB, caused downregulation of ErbB2 and ErbB3, yielding stronger downregulation of the ErbB3-oncogenic signaling axis in in vitro models of lung and breast cancer. These results were validated by in vivo antitumor efficacy of dAd/shErbB3 and oAd/shErbB3.

Proteasome Inhibitors Suppress ErbB Family Expression through HSP90-Mediated Lysosomal Degradation

Although dual EGFR/HER2 tyrosine kinase inhibitor lapatinib has provided effective clinical benefits for HER2-positive breast cancer patients, acquired resistance to this drug remains a major concern. Thus, the development of alternative therapeutic strategies is urgently needed for patients who failed lapatinib treatment. Proteasome inhibitors have been reported to possess high anti-tumor activity to breast cancer cells. Therefore, this study aims to examine whether and how proteasome inhibitor bortezomib can overcome lapatinib resistance. Treatments with several proteasome inhibitors, including Bortezomib, MG132, and proteasome inhibitor I (PSI), as well as the viabilities of both HER2-positive breast cancer cell lines and their lapatinib-resistant clones, were inhibited. Importantly, the expressions of ErbB family were downregulated at both transcriptional and translational levels. Also, our results further indicated that proteasome inhibitors decreased ErbB family expression through lysosomal degradation pathway in a heat shock protein 90 (HSP90)-dependent manner. In this study, our data supported a potential approach to overcome the acquired resistance of HER2-overexpressing breast cancer patients to lapatinib using proteasome inhibitors.

ANKRD44 Gene Silencing: A Putative Role in Trastuzumab Resistance in Her2-Like Breast Cancer

Trastuzumab is an effective therapeutic treatment for Her2-like breast cancer; despite this most of these tumors develop resistance to therapy due to specific gene mutations or alterations in gene expression. Understanding the mechanisms of resistance to Trastuzumab could be a useful tool in order to identify combinations of drugs that elude resistance and allow a better response for the treated patients. Twelve primary biopsies of Her2+/hormone receptor negative (ER-/PgR-) breast cancer patients were selected based on the specific response to neoadjuvant therapy with Trastuzumab and their whole exome was sequenced leading to the identification of 18 informative gene mutations that discriminate patients selectively based on response to treatment. Among these genes, we focused on the study of the ANKRD44 gene to understand its role in the mechanism of resistance to Trastuzumab. The ANKRD44 gene was silenced in Her2-like breast cancer cell line (BT474), obtaining a partially Trastuzumab-resistant breast cancer cell line that constitutively activates the NF-kb protein via the TAK1/AKT pathway. Following this activation an increase in the level of glycolysis in resistant cells is promoted, also confirmed by the up-regulation of the LDHB protein and by an increased TROP2 protein expression, found generally associated with aggressive tumors. These results allow us to consider the ANKRD44 gene as a potential gene involved in Trastuzumab resistance.

Dietary phytochemicals in breast cancer research: anticancer effects and potential utility for effective chemoprevention

Cancerous tissue transformation developing usually over years or even decades of life is a highly complex process involving strong stressors damaging DNA, chronic inflammation, comprehensive interaction between relevant molecular pathways, and cellular cross-talk within the neighboring tissues. Only the minor part of all cancer cases are caused by inborn predisposition; the absolute majority carry a sporadic character based on modifiable risk factors which play a central role in cancer prevention. Amongst most promising candidates for dietary supplements are bioactive phytochemicals demonstrating strong anticancer effects. Abundant evidence has been collected for beneficial effects of flavonoids, carotenoids, phenolic acids, and organosulfur compounds affecting a number of cancer-related pathways. Phytochemicals may positively affect processes of cell signaling, cell cycle regulation, oxidative stress response, and inflammation. They can modulate non-coding RNAs, upregulate tumor suppressive miRNAs, and downregulate oncogenic miRNAs that synergically inhibits cancer cell growth and cancer stem cell self-renewal. Potential clinical utility of the phytochemicals is discussed providing examples for chemoprevention against and therapy for human breast cancer. Expert recommendations are provided in the context of preventive medicine.

A continuous-time multistate Markov model to describe the occurrence and severity of diarrhea events in metastatic breast cancer patients treated with lumretuzumab in combination with pertuzumab and paclitaxel

PURPOSE

To inform lumretuzumab and pertuzumab dose modifications in order to decrease the incidence, severity, and duration of the diarrhea events in metastatic breast cancer patients treated with a combination therapy of lumretuzumab (anti-HER3) in combination with pertuzumab (anti-HER2) and paclitaxel using quantitative clinical pharmacology modeling approaches.

METHODS

The safety and pharmacokinetic (PK) data from three clinical trials (lumretuzumab monotherapy n = 47, pertuzumab monotherapy n = 78, and the combination therapy of lumretuzumab, pertuzumab and paclitaxel n = 35) were pooled together to develop a continuous-time discrete states Markov model describing the dynamics of the diarrhea events.

RESULTS

The model was able to capture the time course of different severities of diarrhea reasonably well. The effect of lumretuzumab and pertuzumab was well described by an E_max function indicating an increased rate of transition from moderate to mild or more severe diarrhea with higher doses. The concentration needed to trigger or worsen diarrhea episodes was estimated to be 120-fold lower in combination therapy compared to monotherapy, suggesting strong synergy between the two monoclonal antibodies. The prophylactic effect of loperamide in a subset of patients was also well captured by the model with a clear tendency to reduce the occurrence of diarrhea events.

CONCLUSIONS

This work shows that PK-toxicity modeling provides insight into how the severity of key adverse events evolves over time and highlights the potential use to support decision making in drug development.

Tumor-linked HER2 expression: association with obesity and lipid-related microenvironment

Obesity is associated with the risk of several health disorders including certain cancers. Among obesity-related cancers, postmenopausal breast carcinoma is a well-studied one. Apart from an increase in certain types of lipids in obesity, excess adipose tissue releases many hormone-like cytokines/adipokines, which are usually pro-inflammatory in nature. Leptin is one of such adipokines and significantly linked with the intracellular signaling pathways of other growth factors such as insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), human epidermal growth factor receptor 2 (HER2). In general, HER2 is overexpressed in roughly 30% of breast carcinomas; its presence indicates aggressive tumor behavior. Conversely, HER2 has certain effects in normal conditions such as differentiation of preadipocytes, cardiovascular health and vitamin D metabolism. HER2 has no known endogenous ligand, but it may form dimers with other three members of the epidermal growth factor receptor (EGFR) family and can activate downstream signaling pathways. Furthermore, HER2 is intimately connected with several enzymes, e.g. fatty acid synthase (FASN), phosphatidylinositol 3-kinase (PI3K), AKT and mechanistic target of rapamycin (mTOR), all of which play significant regulatory roles in lipogenic pathways or lipid metabolism. In obesity-related carcinogenesis, characteristics like insulin resistance and elevated IGF-1 are commonly observed. Both IGF-1 and leptin can modulate EGFR and HER2 signaling pathways. Although clinical studies have shown mixed results, the behavior of HER2+ tumor cells including HER2 levels can be altered by several factors such as obesity, leptin and fatty acids. A precise knowledge is useful in new therapeutic approaches against HER+ tumors.

Synergistic effects of various Her inhibitors in combination with IGF-1R, C-MET and Src targeting agents in breast cancer cell lines

Overexpression of HER2 has been reported in around 25% of human breast cancers. Despite recent advances in HER2 targeted therapy, many patients still experience primary and secondary resistance to such treatments, the mechanisms for which are poorly understood. Here, we investigated the sensitivity of a panel of breast cancer cell lines to treatment with various types of HER-family inhibitors alone or in combination with other tyrosine kinase inhibitors or chemotherapeutic agents. We found that treatment with the second-generation irreversible HER-family inhibitors, particularly afatinib and neratinib, were more effective than treatment with the first-generation reversible inhibitors in inhibiting growth, migration and downstream cell signalling in breast cancer cells. Of the three HER2 overexpressing cell lines in this panel, SKBr3 and BT474 were highly sensitive to treatment with HER-family inhibitors, while MDA-MB-453 was comparatively resistant. Combinations of HER-family inhibitors with NVP-AEW541, dasatinib or crizotinib (inhibitors of IGF-1R, Src and c-Met/ALK, respectively) led to synergistic effects in some of the cell lines examined. In particular, treatment with a combination of Src and HER-family member inhibitors resulted in synergistic growth inhibition of MDA-MB453 cells, implicating Src as a mediator of resistance to HER2-targeting agents. Our results suggest that combining HER-family inhibitors with other TKIs such as dasatinib may have therapeutic advantages in certain breast cancer subtypes and warrants further investigation.

Direct estrogen receptor (ER) / HER family crosstalk mediating sensitivity to lumretuzumab and pertuzumab in ER+ breast cancer

Bidirectional cross talk between members of the human epidermal growth factor family of receptors (HER) and the estrogen receptor (ER) is believed to underlie resistance mechanisms that develop in response to treatment with anti-HER agents and endocrine therapy. We investigated the interaction between HER2, HER3 and the ER in vitro using human embryonic kidney cells transfected with human HER2, HER3, and ERα. We also investigated the additive efficacy of combination regimens consisting of anti-HER3 (lumretuzumab), anti-HER2 (pertuzumab), and endocrine (fulvestrant) therapy in vivo. Our data show that both HER2 and HER3 can directly complex with the ER and can mediate phosphorylation of the ER. Phosphorylation of the ER was only observed in cells that expressed both HER2 and ERα or in heregulin-stimulated cells that expressed both HER3 and ERα. Using a mouse xenograft model of ER+/HER2-low (HER2 immunohistochemistry 1+ or 2+ without gene amplification) human breast cancer we show that the combination of lumretuzumab and pertuzumab is highly efficacious and induces long-lasting tumor regression in vivo and adding endocrine therapy (fulvestrant) to this combination further improved efficacy. In addition, a prolonged clinical response was observed with the combination of lumretuzumab and pertuzumab in a patient with ER+/HER2-low breast cancer who had failed endocrine therapy. These preclinical data confirm that direct cross talk exists between HER2/HER3 and ER which may explain the resistance mechanisms to endocrine therapy and monoclonal antibodies that target HER2 and HER3. Our data also indicate that the triplet of anti-HER2, anti-HER3, and endocrine therapy might be an efficacious combination for treating patients with ER+/HER2-low breast cancer, which is an area of significant unmet medical need.

Pharmacodynamics, pharmacokinetics and clinical efficacy of neratinib in HER2-positive breast cancer and breast cancer with HER2 mutations

INTRODUCTION

Despite the availability of several potent HER2-directed targeted agents, primary and acquired resistance continues to influence patient outcomes in HER2-positive breast cancer. Neratinib is an irreversible pan-HER tyrosine kinase inhibitor in late-phase clinical development.

AREAS COVERED

This review article focuses on neratinib in the treatment of HER2-positive breast cancer - early and metastatic stage - and HER2-mutant breast cancer, with particular emphasis on the pharmacokinetics and pharmacodynamics of the drug.

EXPERT OPINION

The phase III ExteNET trial shows that neratinib improves 2-year invasive disease-free survival after trastuzumab-based adjuvant therapy in early-stage HER2-positive breast cancer, and in particular HER2+/HR+ tumors. Survival data are awaited. The investigational role of neratinib in high-risk patients or conversely in de-escalation dual regimens with other anti-HER2 therapies and without chemotherapy are of interest. Phase II trials show that neratinib has efficacy, either as monotherapy or in combination with other chemotherapeutic or endocrine agents, in patients with HER2-positive metastatic breast cancer and in tumors harboring HER2 mutations. The role of neratinib in therapeutic algorithms of HER2-positive patients, as well as delaying CNS events, awaits the results of ongoing trials such as NALA. Diarrhea, the main toxicity of neratinib, can be effectively managed with early loperamide prophylaxis.

The Potential of panHER Inhibition in Cancer

Purpose: Hyper-activation of the HER (erbB) family receptors, HER 1-4, leads to up-regulation of the three vital signaling pathways: mitogen activated protein kinase, phosphoinositide 3-kinase/AKT, and Janus kinase/signal transducer and activator of transcription pathways. Blocking HER1/EGFR has a limited anticancer effect due to either secondary mutation e.g., T790M or by-pass signaling of other HER members. The emergence of an anti-panHER approach to blockade of these pathways as a cancer treatment may provide a solution to this resistance. This review aimed to provide an overview of the HER signaling pathways and their involvement in tumor progression and examine the current progress in panHER inhibition.

Methods: Recent literature associated with HER signaling pathways and panHER inhibition was reviewed through PubMed and Medline database, followed by critical comparison and analysis.

Results: Pre-clinical studies and clinical trials of panHER inhibitors show promising results, and the potential to improve patient outcomes in solid cancers.

Conclusion: The use of panHER inhibitors in cancers with HER-family hyper-activation, such as other epithelial cancers and sarcoma, is a new direction to research and has potential in clinical cancer therapy in the future.

Therapeutic Considerations in Treating HER2-Positive Metastatic Breast Cancer

Despite advances in detection and treatment, metastatic breast cancer (MBC) remains the second highest cause of cancer-related death for women in the United States. Human epidermal growth factor receptor-2 (HER2) is amplified in 25-30% of breast cancers and is associated with aggressive disease and, historically, with poorer outcomes. The advent of trastuzumab, a monoclonal antibody to HER2, revolutionized the management of HER2-positive breast cancer (BC) in the metastatic and adjuvant settings. However, relapse despite adjuvant trastuzumab and resistance to trastuzumab in the metastatic setting remain substantial clinical problems for many patients with HER2-positive BC. As such, analyzing the mechanisms of trastuzumab resistance and developing new therapy to overcome trastuzumab resistance are research priorities. There has been progress, with the approval of three additional HER2-targeted agents in the last six years: lapatinib, pertuzumab, and ado-trastuzumab emtansine (T-DM1). Other HER2-targeted therapies, including neratinib and afatinib, are in clinical development, and trials of novel agents such as heat shock protein-90 (HSP90) inhibitors, phosphatidylinositol-3-kinase (PI3K) inhibitors, and HER2-targeted vaccines are ongoing. In addition to developing new therapy, research is addressing several unique challenges in the management of HER2-positive MBC. In this article, we discuss advances in the treatment of HER2-positive MBC, with a focus on novel HER2-targeted therapy and HER2-targeted agents recently approved by the United States Food and Drug Administration (FDA). Additionally, we also address the management of brain metastases (BM) and hormone receptor (HR) - positive, HER2-positive MBC.

The emergence of targeted drugs in breast cancer to prevent resistance to endocrine treatment and chemotherapy

INTRODUCTION

Deregulated signaling pathways are associated with resistance to chemotherapy and endocrine treatment, providing a rationale for the implementation of novel targeted therapies in breast cancer therapy. Key molecules targeted therapeutically in ongoing clinical breast cancer trials are phosphoinositide 3-kinase-Akt-mammalian target of rapamycin (mTOR), Src, insulin-like growth factor 1 receptor, heat shock protein-90, histone deacetylases, cyclin-dependent kinases (CDKs), Notch and human epidermal growth factor receptors (HERs).

AREAS COVERED

This review provides an overview of novel targeted agents currently explored in clinical breast cancer trials and registered in ClinicalTrials.gov. The main focus will be on their ability to prevent or reverse endocrine resistance and chemoresistance in breast cancer.

EXPERT OPINION

HER2 targeted agents have extended survival substantially, both in the adjuvant and metastatic setting, pointing to a crucial dependency on this pathway in HER2-amplified breast cancer, including drug resistance reversal. While data on mTOR inhibitors are encouraging and preliminary results on CDK4/6 and Src inhibitors exciting, so far other targeted agents have been of limited benefit when added in concert with conventional therapies. Future clinical trials should systematically explore biomarkers and defects in functional gene cascades to identify relevant biological mechanisms to be targeted therapeutically in breast cancer.

The unpluggable in pursuit of the undruggable: tackling the dark matter of the cancer therapeutics universe

The notion that targeted drugs can unplug gain-of-function tumor pathways has revitalized pharmaceutical research, but the survival benefits of this strategy have so far proven modest. A weakness of oncogene-blocking approaches is that they do not address the problem of cancer progression as selected by the recessive phenotypes of genetic instability and apoptotic resistance which in turn arise from loss-of-function – i.e., undruggable – defects of caretaker (e.g., BRCA, MLH1) or gatekeeper (e.g., TP53, PTEN) suppressor genes. Genetic instability ensures that rapid cell kill is balanced by rapid selection for apoptotic resistance and hence for metastasis, casting doubt on the assumption that cytotoxicity (“response”) remains the best way to identify survival-enhancing drugs. In the absence of gene therapy, it is proposed here that caretaker-defective (high-instability) tumors may be best treated with low-lethality drugs inducing replicative (RAS-RAF-ERK) arrest or dormancy, causing “stable disease” rather than tumorilytic remission. Gatekeeper-defective (death-resistant) tumors, on the other hand, may be best managed by combining survival (PI3K-AKT-mTOR) pathway blockade with metronomic or sequential pro-apoptotic drugs.

HER2/HER3 regulates extracellular acidification and cell migration through MTK1 (MEKK4)

Human MAP3K4 (MTK1) functions upstream of mitogen activated protein kinases (MAPKs). In this study we show MTK1 is required for human epidermal growth factor receptor 2/3 (HER2/HER3)-heregulin beta1 (HRG) induced cell migration in MCF-7 breast cancer cells. We demonstrate that HRG stimulation leads to association of MTK1 with activated HER3 in MCF-7 and T-47D breast cancer cells. Activated HER3 association with MTK1 is dependent on HER2 activation and is decreased by pre-treatment with the HER2 inhibitor, lapatinib. Moreover, we also identify the actin interacting region (AIR) on MTK1. Disruption of actin cytoskeletal polymerization with cytochalasin D inhibited HRG induced MTK1/HER3 association. Additionally, HRG stimulation leads to extracellular acidification that is independent of cellular proliferation. HRG induced extracellular acidification is significantly inhibited when MTK1 is knocked down in MCF-7 cells. Similarly, pre-treatment with lapatinib significantly decreased HRG induced extracellular acidification. Extracellular acidification is linked with cancer cell migration. We performed scratch assays that show HRG induced cell migration in MCF-7 cells. Knockdown of MTK1 significantly inhibited HRG induced cell migration. Furthermore, pre-treatment with lapatinib also significantly decreased cell migration. Cell migration is required for cancer cell metastasis, which is the major cause of cancer patient mortality. We identify MTK1 in the HER2/HER3-HRG mediated extracellular acidification and cell migration pathway in breast cancer cells.

Prognostic significance of human epidermal receptor (HER)- 3 immunohistochemical expression in patients with metastatic breast cancer

BACKGROUND

Previous reports have shown that human epidermal receptor (HER)-3 overexpression may be associated with poor prognosis in patients with breast cancer, but results have been conflicting. In this study, we sought to investigate the prognostic significance of HER-3 immunohistochemical expression in patients with metastatic breast cancer.

METHODS

We retrospectively analyzed HER-3 immunohistochemical expression profiles in 45 paraffin-embedded specimens from patients who had been treated between 1996 and 2006 in the Department of Oncology of the Uludag University School of Medicine, Bursa, Turkey. Membranous or cytoplasmic dominant expression patterns of HER-3 were analyzed using the Rajkumar score and a cytoplasmic 4-point scoring system, respectively. Progression-free survival (PFS) and overall survival (OS) served as the main outcome measures.

RESULTS

The median PFS in the study participants was 9 months (interquartile range: 4.5-13 months), whereas the median OS was 20 months (interquartile range: 7.5-28 months). Categorization of the patient population according to HER-3 positive immunohistochemical expression did not reveal any statistically significant difference in terms of both PFS (p=0.70) and OS (p=0.81). The results of multivariable Cox regression analysis indicated that tumor size was the only independent predictor of PFS, whereas estrogen and progesterone receptor status was independently associated with OS.

CONCLUSIONS

HER-3 immunohistochemical expression did not correlate with outcomes in Turkish patients with metastatic breast cancer. Although our results suggest that HER-3 expression in cancer specimens is not of prognostic significance, further prospective studies are warranted to confirm these results.

Profiling epidermal growth factor receptor and heregulin receptor 3 heteromerization using receptor tyrosine kinase heteromer investigation technology

Heteromerization can play an important role in regulating the activation and/or signal transduction of most forms of receptors, including receptor tyrosine kinases (RTKs). The study of receptor heteromerization has evolved extensively with the emergence of resonance energy transfer based approaches such as bioluminescence resonance energy transfer (BRET). Here, we report an adaptation of our Receptor-Heteromer Investigation Technology (Receptor-HIT) that has recently been published as the G protein-coupled receptor (GPCR) Heteromer Identification Technology (GPCR-HIT). We now demonstrate the utility of this approach for investigating RTK heteromerization by examining the functional interaction between the epidermal growth factor (EGF) receptor (EGFR; also known as erbB1/HER1) and heregulin (HRG) receptor 3 (HER3; also known as erbB3) in live HEK293FT cells using recruitment of growth factor receptor-bound protein 2 (Grb2) to the activated receptors. We found that EGFR and HER3 heteromerize specifically as demonstrated by HRG inducing a BRET signal between EGFR/Rluc8 and Grb2/Venus only when HER3 was co-expressed. Similarly, EGF stimulation promoted a specific BRET signal between HER3/Rluc8 and Grb2/Venus only when EGFR was co-expressed. Both EGF and HRG effects on Grb2 interaction are dose-dependent, and specifically blocked by EGFR inhibitor AG-1478. Furthermore, truncation of HER3 to remove the putative Grb2 binding sites appears to abolish EGF-induced Grb2 recruitment to the EGFR-HER3 heteromer. Our results support the concept that EGFR interacts with Grb2 in both constitutive and EGF-dependent manners and this interaction is independent of HER3 co-expression. In contrast, HER3-Grb2 interaction requires the heteromerization between EGFR and HER3. These findings clearly indicate the importance of EGFR-HER3 heteromerization in HER3-mediated Grb2-dependent signaling pathways and supports the central role of HER3 in the diversity and regulation of HER family functioning.

Regulation of survival, proliferation, invasion, angiogenesis, and metastasis of tumor cells through modulation of inflammatory pathways by nutraceuticals

Almost 25 centuries ago, Hippocrates, the father of medicine, proclaimed "Let food be thy medicine and medicine be thy food." Exploring the association between diet and health continues today. For example, we now know that as many as 35% of all cancers can be prevented by dietary changes. Carcinogenesis is a multistep process involving the transformation, survival, proliferation, invasion, angiogenesis, and metastasis of the tumor and may take up to 30 years. The pathways associated with this process have been linked to chronic inflammation, a major mediator of tumor progression. The human body consists of about 13 trillion cells, almost all of which are turned over within 100 days, indicating that 70,000 cells undergo apoptosis every minute. Thus, apoptosis/cell death is a normal physiological process, and it is rare that a lack of apoptosis kills the patient. Almost 90% of all deaths due to cancer are linked to metastasis of the tumor. How our diet can prevent cancer is the focus of this review. Specifically, we will discuss how nutraceuticals, such as allicin, apigenin, berberine, butein, caffeic acid, capsaicin, catechin gallate, celastrol, curcumin, epigallocatechin gallate, fisetin, flavopiridol, gambogic acid, genistein, plumbagin, quercetin, resveratrol, sanguinarine, silibinin, sulforaphane, taxol, gamma-tocotrienol, and zerumbone, derived from spices, legumes, fruits, nuts, and vegetables, can modulate inflammatory pathways and thus affect the survival, proliferation, invasion, angiogenesis, and metastasis of the tumor. Various cell signaling pathways that are modulated by these agents will also be discussed.

Predictive biomarkers of sensitivity to the phosphatidylinositol 3' kinase inhibitor GDC-0941 in breast cancer preclinical models

PURPOSE

The class I phosphatidylinositol 3' kinase (PI3K) plays a major role in proliferation and survival in a wide variety of human cancers. A key factor in successful development of drugs targeting this pathway is likely to be the identification of responsive patient populations with predictive diagnostic biomarkers. This study sought to identify candidate biomarkers of response to the selective PI3K inhibitor GDC-0941.

EXPERIMENTAL DESIGN

We used a large panel of breast cancer cell lines and in vivo xenograft models to identify candidate predictive biomarkers for a selective inhibitor of class I PI3K that is currently in clinical development. The approach involved pharmacogenomic profiling as well as analysis of gene expression data sets from cells profiled at baseline or after GDC-0941 treatment.

RESULTS

We found that models harboring mutations in PIK3CA, amplification of human epidermal growth factor receptor 2, or dual alterations in two pathway components were exquisitely sensitive to the antitumor effects of GDC-0941. We found that several models that do not harbor these alterations also showed sensitivity, suggesting a need for additional diagnostic markers. Gene expression studies identified a collection of genes whose expression was associated with in vitro sensitivity to GDC-0941, and expression of a subset of these genes was found to be intimately linked to signaling through the pathway.

CONCLUSION

Pathway focused biomarkers and the gene expression signature described in this study may have utility in the identification of patients likely to benefit from therapy with a selective PI3K inhibitor.

Molecular targets of nutraceuticals derived from dietary spices: potential role in suppression of inflammation and tumorigenesis

Despite the fact cancer is primarily a preventable disease, recent statistics indicate cancer will become the number one killer worldwide in 2010. Since certain cancers are more prevalent in the people of some countries than others, suggests the role of lifestyle. For instance cancer incidence among people from the Indian subcontinent, where most spices are consumed, is much lower than that in the Western World. Spices have been consumed for centuries for a variety of purposes-as flavoring agents, colorants, and preservatives. However, there is increasing evidence for the importance of plant-based foods in regular diet to lowering the risk of most chronic diseases, so spices are now emerging as more than just flavor aids, but as agents that can not only prevent but may even treat disease. In this article, we discuss the role of 41 common dietary spices with over 182 spice-derived nutraceuticals for their effects against different stages of tumorigenesis. Besides suppressing inflammatory pathways, spice-derived nutraceuticals can suppress survival, proliferation, invasion, and angiogenesis of tumor cells. We discuss how spice-derived nutraceuticals mediate such diverse effects and what their molecular targets are. Overall our review suggests "adding spice to your life" may serve as a healthy and delicious way to ward off cancer and other chronic diseases.

Neuregulin-mediated ErbB3 signaling is required for formation of zebrafish dorsal root ganglion neurons

Dorsal root ganglia (DRGs) arise from trunk neural crest cells that emerge from the dorsal neuroepithelium and coalesce into segmental streams that migrate ventrally along the developing somites. Proper formation of DRGs involves not only normal trunk neural crest migration, but also the ability of DRG progenitors to pause at a particular target location where they can receive DRG-promoting signals. In mammalian embryos, a receptor tyrosine kinase proto-oncogene, ErbB3, is required for proper trunk neural crest migration. Here, we show that in zebrafish mutants lacking ErbB3 function, neural crest cells do not pause at the location where DRGs normally form and DRG neurons are not generated. We also show that these mutants lack trunk neural crest-derived sympathetic neurons, but that cranial neural crest-derived enteric neurons appear normal. We isolated three genes encoding neuregulins, ErbB3 ligands, and show that two neuregulins function together in zebrafish trunk neural crest cell migration and in DRG formation. Together, our results suggest that ErbB3 signaling is required for normal migration of trunk, but not cranial, neural crest cells.

Targeted therapies for cancer of the gallbladder

PURPOSE OF REVIEW

Adenocarcinomas of the gallbladder are uncommon, aggressive tumors with poor survival. This review summarizes advances in understanding the biology of gallbladder cancer.

RECENT FINDINGS

Published response rates of adenocarcinomas of the gallbladder to chemotherapy are less than 30% and no survival benefit has been demonstrated from palliative systemic therapy. New information on the molecular carcinogenic mechanisms of these malignancies, combined with findings from animal models, may lead to improved treatment for patients.

SUMMARY

Improved understanding of the molecular carcinogenesis of adenocarcinomas of the gallbladder, coupled with the availability of novel molecularly 'targeted' chemotherapeutic agents, may improve outcome for patients.

Sensitizing HER2-overexpressing cancer cells to luteolin-induced apoptosis through suppressing p21(WAF1/CIP1) expression with rapamycin

HER2 overexpression, which confers resistance to various therapeutic regimens, correlates with a poor clinical prognosis. In this study, we showed that luteolin, a naturally occurring flavonoid, is a potent stimulator of HER2 degradation. Luteolin effectively inhibited cell proliferation and induced apoptosis in HER2-overexpressing cancer cells. Furthermore, we found that low doses of luteolin up-regulated p21 expression and high doses of luteolin down-regulated its expression. Examination of the Akt/mammalian target of rapamycin (mTOR) signaling revealed that this signaling was only transiently inhibited by low doses of luteolin, which suggested that the inability to cause sustained Akt/mTOR inhibition may contribute to p21 induction and provide a survival advantage to HER2-overexpressing cancer cells. To test this hypothesis, we showed that the combined use of luteolin and mTOR inhibitor rapamycin prevented low doses of luteolin from inducing p21 expression, and HER2-overexpressing cancer cells would be sensitized toward luteolin-induced apoptosis. In addition, p21 small interfering RNA also increased the luteolin-induced cell death. In nude mice with xenografted SKOV3.ip1-induced tumors, luteolin significantly inhibited HER2 expression and tumor growth in a dose-dependent manner, and rapamycin further enhanced the effect of luteolin with a concomitant p21 inhibition. These results reveal an intriguing finding that suppressing p21 expression might have therapeutic implications and further suggest that combination of mTOR inhibitors may be a promising strategy to help increase the efficacy of preventive or therapeutic compounds against HER2-overexpressing tumors.

ErbB receptors and epithelial-cadherin-catenin complex in human carcinomas

The ErbB family of receptor tyrosine kinases have important roles in maintaining normal epithelial cell function. The ErbBs are involved in the interaction between cells and cell-matrix adhesion molecules and have proven critical in maintaining the integrity of the epithelial cell environment. Deregulation of these tyrosine receptors has been associated with several human diseases. In particular, the expression or activation of epidermal growth factor receptor (EGFR) and ErbB2 is altered in many epithelial tumors. Epithelial (E)-cadherin is another major molecule expressed by epithelial cells. To create efficient cell-cell adhesion, E-cadherin couples its cytoplasmic domain to catenins and the actin cytoskeleton. The loss of intercellular adhesion appears to be a fundamental aspect of the neoplastic phenomena. In addition, EGFR and ErbB2 signaling associated with the E-cadherin-catenin complex has been demonstrated in normal and cancer cells. This signaling is involved in regulating cell adhesion and the invasive growth of cancers. This article provides an overview of the interaction between the ErbB tyrosine receptors and the E-cadherin-catenin complex in human carcinomas.