Differential impact of EGFR-targeted therapies on hypoxia responses: implications for treatment sensitivity in triple-negative metastatic breast cancer

Tissue factor (coagulation factor III): a potential double-edge molecule to be targeted and re-targeted toward cancer

Tissue factor (TF) is a protein that plays a critical role in blood clotting, but recent research has also shown its involvement in cancer development and progression. Herein, we provide an overview of the structure of TF and its involvement in signaling pathways that promote cancer cell proliferation and survival, such as the PI3K/AKT and MAPK pathways. TF overexpression is associated with increased tumor aggressiveness and poor prognosis in various cancers. The review also explores TF's role in promoting cancer cell metastasis, angiogenesis, and venous thromboembolism (VTE). Of note, various TF-targeted therapies, including monoclonal antibodies, small molecule inhibitors, and immunotherapies have been developed, and preclinical and clinical studies demonstrating the efficacy of these therapies in various cancer types are now being evaluated. The potential for re-targeting TF toward cancer cells using TF-conjugated nanoparticles, which have shown promising results in preclinical studies is another intriguing approach in the path of cancer treatment. Although there are still many challenges, TF could possibly be a potential molecule to be used for further cancer therapy as some TF-targeted therapies like Seagen and Genmab's tisotumab vedotin have gained FDA approval for treatment of cervical cancer. Overall, based on the overviewed studies, this review article provides an in-depth overview of the crucial role that TF plays in cancer development and progression, and emphasizes the potential of TF-targeted and re-targeted therapies as potential approaches for the treatment of cancer.

Targeting carbonic anhydrase IX and XII isoforms with small molecule inhibitors and monoclonal antibodies

Carbonic anhydrases IX and CAXII (CAIX/CAXII) are transmembrane zinc metalloproteins that catalyze a very basic but crucial physiological reaction: the conversion of carbon dioxide into bicarbonate with a release of the proton. CA, especially CAIX and CAXII isoforms gained the attention of many researchers interested in anticancer drug design due to pivotal functions of enzymes in the cancer cell metastasis and response to hypoxia, and their expression restricted to malignant cells. This offers an opportunity to develop new targeted therapies with fewer side effects. Continuous efforts led to the discovery of a series of diverse compounds with the most abundant sulphonamide derivatives. Here we review current knowledge considering small molecule and antibody-based targeting of CAIX/CAXII in cancer.

Chemoresistance in breast cancer: PI3K/Akt pathway inhibitors vs the current chemotherapy

Breast cancer is the most prevalent type of cancer among women. Several types of drugs, targeting the specific proteins expressed on the breast cancer cell surface (such as receptor tyrosine kinases and immune checkpoint regulators) and proteins involved in cell cycle and motility (including cyclin-dependent kinases, DNA stabilisers, and cytoskeleton modulators) are approved for different subtypes of breast cancer. However, breast cancer also has a poor response to conventional chemotherapy due to intrinsic and acquired resistance, and an Akt fingerprint is detectable in most drug-resistant cases. Overactivation of Akt and its upstream and downstream regulators in resistant breast cancer cells is considered a major potential target for novel anti-cancer therapies, suggesting that Akt signalling acts as a cellular mechanism against chemotherapy. The present review has shown that sustained activation of Akt results in resistance to different types of chemotherapy. Akt signalling plays a cellular defence role against chemotherapy and (1) enhances multi-drug resistance, (2) increases reactive oxygen species at breast tumor microenvironment, (3) enhances anaerobic metabolism, (4) inhibits the tricarboxylic cycle, (5) promotes PD-L1 upregulation, (6) inhibits apoptosis, (7) increases glucose uptake, and more importantly (8) recruits and interconnects the plasma membrane, nucleus, endoplasmic reticulum, and mitochondria to hijack breast cancer cells and rescue these cells from chemotherapy. Therefore, Akt signalling is considered a cellular defence mechanism employed against chemotherapeutic effects. In addition, interfering roles of PI3K/Akt signalling on the current cytotoxic and molecularly targeted therapy as well as immunotherapy of breast cancer are discussed with a clinical approach. Although, alpelisib, a PIK3CA inhibitor, is the only PI3K/Akt pathway inhibitor approved for breast cancer, we also highlight well-evaluated inhibitors of PI3K/Akt signalling based on different subtypes of breast cancer, which are under clinical trials whether as monotherapy or in combination with other types of chemotherapy.

DCE-MRI quantitative transport mapping for noninvasively detecting hypoxia inducible factor-1α, epidermal growth factor receptor overexpression, and Ki-67 in nasopharyngeal carcinoma patients

BACKGROUND

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) has the potential to noninvasively detect expression of hypoxia inducible factor-1-alpha (HIF-1α), epidermal growth factor receptor (EGFR), and Ki-67 in nasopharyngeal carcinoma (NPC) by quantitatively measuring tumor blood flow, vascularity, and permeability.

PURPOSE

We aim to explore the utility of DCE-MRI in detecting HIF-1α, EGFR, and Ki-67 expression levels using traditional Kety's/Tofts' modeling and quantitative transport mapping (QTM).

MATERIALS AND METHODS

Eighty-nine NPC patients underwent DCE-MRI before treatment were enrolled. DCE-MRI was processed to generate the following kinetic parameters: |u| and D from the QTM model, tumor blood flow (TBF) from Kety's model, and K^trans, V_e, and K_ep from Tofts' model. Pretreatment levels of HIF-1α, EGFR, and Ki-67 were assessed by immunohistochemistry and classified into low and high expression groups.

RESULTS

|u| (p < 0.001) and TBF (p = 0.015) values were significantly higher in the HIF-1α high-expression group compared to low-expression group. Only K^trans (p = 0.016) was significantly higher in the EGFR high-expression group. Only |u| (p < 0.001) values were significantly higher in the Ki-67 high-expression group compared to low-expression group. Multiple linear regression analyses showed that |u| independently correlated with HIF-1α and Ki-67 expression, and K^trans independently correlated with EGFR. The areas under the ROC curves of |u| for HIF-1α and Ki-67, and K^trans for EGFR were 0.83, 0.74, and 0.70, respectively.

CONCLUSION

|u| and K^trans derived from DCE-MRI may be considered as noninvasive imaging markers for detecting hypoxia and proliferation in NPC patients.

Tissue factor as a new target for CAR-NK cell immunotherapy of triple-negative breast cancer

Triple-negative breast cancer (TNBC), representing ~15% of globally diagnosed breast cancer, is typically an incurable malignancy due to the lack of targetable surface targets for development of effective therapy. To address the unmet need for TNBC treatment, we recently determined that tissue factor (TF) is a useful surface target in 50–85% of patients with TNBC and developed a second-generation TF-targeting antibody-like immunoconjugate (called L-ICON) for preclinical treatment of TNBC. Using the chimeric antigen receptor (CAR) approach, here we develop and test TF-targeting CAR-engineered natural killer (TF-CAR-NK) cells that co-express CD16, the Fc receptor (FcγIII) to mediate antibody-dependent cellular toxicity (ADCC), for a preclinical assessment of immunotherapy of TNBC using TF-CAR-NK cell as single agent therapy and in combination with L-ICON. Our preclinical results demonstrate that TF-CAR-NK cells alone could kill TNBC cells and its efficacy was enhanced with L-ICON ADCC in vitro. Moreover, TF-CAR-NK cells were effective in vivo for the treatment of TNBC in cell line- and patient’s tumor-derived xenograft mouse models. Thus, this study established the proof of concept of targeting TF as a new target in CAR-NK immunotherapy for effective treatment of TNBC and may warrant further preclinical study and potentially future investigation in TNBC patients.

Hypoxia-inducible factor-1 signaling pathway influences the sensitivity of HCC827 cells to gefitinib

The majority of patients with non-small cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations inevitably progress in stage despite an initial substantial and rapid response to EGFR-tyrosine kinase inhibitors (EGFR-TKIs). Previous research indicates that hypoxia may be associated with resistance to EGFR-TKIs in EGFR mutation-positive NSCLC. Therefore, the present study regulated the activity of hypoxia-inducible factor-1 (HIF-1) signaling pathway to observe if it is able to alter the sensitivity of lung cancer cells to gefitinib. The present study selected 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) and dimethyloxalylglycine (DMOG) as a HIF-1 signaling pathway inhibitor and activator, respectively, on HCC827 cells. Cells were incubated with different treatments for different durations: A blank control, DMOG, gefitinib, or DMOG and gefitinib combined, for 36 and 48 h; and then a blank control, YC-1, gefitinib, or YC-1 and gefitinib combined, for 16 and 28 h. A western blot analysis assay was performed to evaluate the protein expression levels of HIF-1α and phosphorylated hepatocyte growth factor receptor (p-MET), an MTT assay was used to determine cell proliferation, a colony formation assay was used to investigate the colony-forming ability and a wound healing assay was used to test the cell migration ability. Additionally, Pearson's correlation analysis was used to evaluate the correlation between p-Met and HIF-1α expression levels. Finally, it was identified that gefitinib and DMOG combined notably improve the growth and cell migration ability of HCC827 cells, compared with gefitinib alone. When gefitinib and YC-1 were combined, the inhibiting effect on the growth and cell migration ability of HCC827 cells was substantially enhanced, compared with the control cells. Pearson's correlation analysis revealed that the p-Met expression level had a strong positive correlation with HIF-1α expression levels. Thus, it was concluded that the HIF-1 signaling pathway influences the sensitivity of HCC827 cells to gefitinib. The positive correlation between p-Met and HIF-1α expression levels may be the underlying mechanism of the HIF-1 signaling pathway influencing the sensitivity of HCC827 cells to gefitinib.

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.

Targeting Tissue Factor for Immunotherapy of Triple-Negative Breast Cancer Using a Second-Generation ICON

Triple-negative breast cancer (TNBC) is a leading cause of breast cancer death and is often associated with BRCA1 and BRCA2 mutation. Due to the lack of validated target molecules, no targeted therapy for TNBC is approved. Tissue factor (TF) is a common yet specific surface target receptor for cancer cells, tumor vascular endothelial cells, and cancer stem cells in several types of solid cancers, including breast cancer. Here, we report evidence supporting the idea that TF is a surface target in TNBC. We used in vitro cancer lines and in vivo tumor xenografts in mice, all with BRCA1 or BRCA2 mutations, derived from patients' tumors. We showed that TF is overexpressed on TNBC cells and tumor neovasculature in 50% to 85% of TNBC patients (n = 161) and in TNBC cell line-derived xenografts (CDX) and patient-derived xenografts (PDX) from mice, but was not detected in adjacent normal breast tissue. We then describe the development of a second-generation TF-targeting immunoconjugate (called L-ICON1, for lighter or light chain ICON) with improved efficacy and safety profiles compared with the original ICON. We showed that L-ICON1 kills TNBC cells in vitro via antibody-dependent cell-mediated cytotoxicity and can be used to treat human and murine TNBC CDX as well as PDX in vivo in orthotopic mouse models. Thus, TF could be a useful target for the development of immunotherapeutics for TNBC patients, with or without BRCA1 and BRCA2 mutations. Cancer Immunol Res; 6(6); 671-84. ©2018 AACR.

Quantification of hypoxia-related gene expression as a potential approach for clinical outcome prediction in breast cancer

Breast cancers are solid tumors frequently characterized by regions with low oxygen concentrations. Cellular adaptations to hypoxia are mainly determined by “hypoxia inducible factors” that mediate transcriptional modifications involved in drug resistance and tumor progression leading to metastasis and relapse occurrence. In this study, we investigated the prognostic value of hypoxia-related gene expression in breast cancer. A systematic review was conducted to select a set of 45 genes involved in hypoxia signaling pathways and breast tumor progression. Gene expression was quantified by RT-qPCR in a retrospective series of 32 patients with invasive ductal carcinoma. Data were analyzed in relation to classical clinicopathological criteria and relapse occurrence. Coordinated overexpression of selected genes was observed in high-grade and HER2+ tumors. Hierarchical cluster analysis of gene expression significantly segregated relapsed patients (p = 0.008, Chi² test). All genes (except one) were up-regulated and six markers were significantly expressed in tumors from recurrent patients. The expression of this 6-gene set was used to develop a basic algorithm for identifying recurrent patients according to a risk score of relapse. Analysis of Kaplan-Meier relapse-free survival curves allowed the definition of a threshold score of 2 (p = 0.021, Mantel-Haenszel test). The risk of recurrence was increased by 40% in patients with a high score. In addition to classical prognostic factors, we showed that hypoxic markers have potential prognostic value for outcome and late recurrence prediction, leading to improved treatment decision-making for patients with early-stage invasive breast cancer. It will be necessary to validate the clinical relevance of this prognostic approach through independent studies including larger prospective patient cohorts.

Engineered Breast Cancer Cell Spheroids Reproduce Biologic Properties of Solid Tumors

Solid tumors develop as 3D tissue constructs. As tumors grow larger, spatial gradients of nutrients and oxygen and inadequate diffusive supply to cells distant from vasculature develops. Hypoxia initiates signaling and transcriptional alterations to promote survival of cancer cells and generation of cancer stem cells (CSCs) that have self-renewal and tumor-initiation capabilities. Both hypoxia and CSCs are associated with resistance to therapies and tumor relapse. This study demonstrates that 3D cancer cell models, known as tumor spheroids, generated with a polymeric aqueous two-phase system (ATPS) technology capture these important biological processes. Similar to solid tumors, spheroids of triple negative breast cancer cells deposit major extracellular matrix proteins. The molecular analysis establishes presence of hypoxic cells in the core region and expression of CSC gene and protein markers including CD24, CD133, and Nanog. Importantly, these spheroids resist treatment with chemotherapy drugs. A combination treatment approach using a hypoxia-activated prodrug, TH-302, and a chemotherapy drug, doxorubicin, successfully targets drug resistant spheroids. This study demonstrates that ATPS spheroids recapitulate important biological and functional properties of solid tumors and provide a unique model for studies in cancer research.

Cancer metastasis and EGFR signaling is suppressed by amiodarone-induced versican V2

Extracellular matrix components play an active role in cancer progression and prognosis. Versican, a large extracellular matrix proteoglycan, can promote cancer metastasis through facilitating cell proliferation, adhesion, migration and angiogenesis. We had previously demonstrated that amiodarone caused ectopic overexpression of similar to versican b (s-vcanb), inhibited EGFR/GSK3β/Snail signaling, and enhanced Cdh5 at the heart field of zebrafish, indicating interference with epithelial-mesenchymal transition (EMT). Since S-vcanb is homologous to mammalian versican V2 isoform, we examined the effects of amiodarone on mammalian tumor proliferation, migration, invasion and metastasis in vitro and in vivo and on EMT signaling pathways. Monolayer wound assays and extracellular matrix transwell invasion assays showed reduced migration and invasion by 15 μM amiodarone treated B16OVA, JC, 4T-1, MDA-MB-231 and MCF-7 tumor cell lines. All cancer cell lines showed reduced metastatic capabilities in vivo after treatment with amiodarone in experimental animals. Western blots revealed that EMT-related transcription factors Snail and Twist were reduced and E-cadherin was enhanced in amiodarone treated cells through an EGFR/ERK/GSK3β-dependent pathway. Immunohistochemistry showed amiodarone lead to increased expression of versican V2 isoform concomitant with reduced versican V1. Our study illustrated the role of versican v2 in EMT modulation and cancer suppression by amiodarone treatment.

Novel cell-penetrating peptide-loaded nanobubbles synergized with ultrasound irradiation enhance EGFR siRNA delivery for triple negative Breast cancer therapy

The lack of safe and effective gene delivery strategies remains a bottleneck for cancer gene therapy. Here, we describe the synthesis, characterization, and application of cell-penetrating peptide (CPP)-loaded nanobubbles (NBs), which are characterized by their safety, strong penetrating power and high gene loading capability for gene delivery. An epidermal growth factor receptor (EGFR)-targeted small interfering RNA (siEGFR) was transfected into triple negative breast cancer (TNBC) cells via prepared CPP-NBs synergized with ultrasound-targeted microbubble destruction (UTMD) technology. Fluorescence microscopy showed that siEGFR and CPP were loaded on the shells of the NBs. The transfection efficiency and cell proliferation levels were evaluated by FACS and MTT assays, respectively. In addition, in vivo experiments showed that the expression of EGFR mRNA and protein could be efficiently downregulated and that the growth of a xenograft tumor derived from TNBC cells could be inhibited. Our results indicate that CPP-NBs carrying siEGFR could potentially be used as a promising non-viral gene vector that can be synergized with UTMD technology for efficient TNBC therapy.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Stimulus-dependent differences in signalling regulate epithelial-mesenchymal plasticity and change the effects of drugs in breast cancer cell lines

Introduction

The normal process of epithelial mesenchymal transition (EMT) is subverted by carcinoma cells to facilitate metastatic spread. Cancer cells rarely undergo a full conversion to the mesenchymal phenotype, and instead adopt positions along the epithelial-mesenchymal axis, a propensity we refer to as epithelial mesenchymal plasticity (EMP). EMP is associated with increased risk of metastasis in breast cancer and consequent poor prognosis. Drivers towards the mesenchymal state in malignant cells include growth factor stimulation or exposure to hypoxic conditions.

Methods

We have examined EMP in two cell line models of breast cancer: the PMC42 system (PMC42-ET and PMC42-LA sublines) and MDA-MB-468 cells. Transition to a mesenchymal phenotype was induced across all three cell lines using epidermal growth factor (EGF) stimulation, and in MDA-MB-468 cells by hypoxia. We used RNA sequencing to identify gene expression changes that occur as cells transition to a more-mesenchymal phenotype, and identified the cell signalling pathways regulated across these experimental systems. We then used inhibitors to modulate signalling through these pathways, verifying the conclusions of our transcriptomic analysis.

Results

We found that EGF and hypoxia both drive MDA-MB-468 cells to phenotypically similar mesenchymal states. Comparing the transcriptional response to EGF and hypoxia, we have identified differences in the cellular signalling pathways that mediate, and are influenced by, EMT. Significant differences were observed for a number of important cellular signalling components previously implicated in EMT, such as HBEGF and VEGFA.

We have shown that EGF- and hypoxia-induced transitions respond differently to treatment with chemical inhibitors (presented individually and in combinations) in these breast cancer cells. Unexpectedly, MDA-MB-468 cells grown under hypoxic growth conditions became even more mesenchymal following exposure to certain kinase inhibitors that prevent growth-factor induced EMT, including the mTOR inhibitor everolimus and the AKT1/2/3 inhibitor AZD5363.

Conclusions

While resulting in a common phenotype, EGF and hypoxia induced subtly different signalling systems in breast cancer cells. Our findings have important implications for the use of kinase inhibitor-based therapeutic interventions in breast cancers, where these heterogeneous signalling landscapes will influence the therapeutic response.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-015-0106-x) contains supplementary material, which is available to authorized users.

Triple negative breast carcinoma EGFR amplification is not associated with EGFR, Kras or ALK mutations

Background:

The amplification of epidermal growth factor receptor (EGFR) in triple negative breast carcinomas (TNBC) suggests its potential therapeutic application, as for HER-2, using standardised methods of measurement. In this regard, we aimed to compare several methods for evaluating EGFR amplification along with potential mutations for suitability in clinical practice.

Methods:

Tissue sections of 138 TNBCs were used (1) to compare EGFR amplification and expression by silver in situ hybridisation (SISH) to qPCR and immunohistochemistry (IHC) and (2) to search for EGFR mutations, along with Kras, PI3K, Braf and HER-2 mutations and echinoderm microtubule associated protein like 4-anaplastic lymphoma kinase (EML4-ALK) translocation.

Results:

(1) Amplification of EGFR was observed in well-characterised TNBCs (up to 92%); (2) qPCR correlated with SISH with 94% specificity and 75.6% sensitivity; (3) IHC correlated with SISH with 97% sensitivity and 78% specificity; (4) no EGFR, Kras mutations or EML4-ALK translocations were found, but PI3K and Braf mutations were observed in 26% of cases; and (5) small, acentric circular extrachromosomal DNA similar to ‘double minutes' in glioblastomas was observed in 18% of SISH sections.

Conclusions:

SISH and IHC are methods that are suitable in clinical practice to screen for EGFR amplification and overexpression, which are frequently observed in TNBC. Patients with TNBC are potential candidates for EGFR-targeted therapy combined with PI3K and Braf inhibitors.

The potential role of nanotechnology in therapeutic approaches for triple negative breast cancer

Triple Negative Breast Cancer, TNBC, a highly aggressive and metastatic type of breast cancer, is characterized by loss of expression of the estrogen receptor (ER), progesterone receptor (PR), and a lack of overexpression of the human epidermal growth factor receptor 2 (HER2). It is a heterogeneous group of tumors with diverse histology, molecular uniqueness and response to treatment. Unfortunately, TNBC patients do not benefit from current anti-HER2 or hormone positive targeted breast cancer treatments; consequently, these patients rely primarily on chemotherapy. However, the 5-year survival rate for woman with metastatic TNBC is less than 30%. As a result of ineffective treatments, TNBC tumors often progress to metastatic lesions in the brain and lung. Brain metastases of invasive breast cancer are associated with 1 and 2 year survival rate of 20% and <2% respectively. Because the only current systemic treatment for TNBC is chemotherapy, alternative targeted therapies are urgently needed to improve the prognosis for TNBC patients. This review is focused on opportunities for developing new approaches for filling the current void in an effective treatment for TNBC patients.

Run-in phase III trial design with pharmacodynamics predictive biomarkers

BACKGROUND

Developments in biotechnology have stimulated the use of predictive biomarkers to identify patients who are likely to benefit from a targeted therapy. Several randomized phase III designs have been introduced for development of a targeted therapy using a diagnostic test. Most such designs require biomarkers measured before treatment. In many cases, it has been very difficult to identify such biomarkers. Promising candidate biomarkers can sometimes be effectively measured after a short run-in period on the new treatment.

METHODS

We introduce a new design for phase III trials with a candidate predictive pharmacodynamic biomarker measured after a short run-in period. Depending on the therapy and the biomarker performance, the trial would either randomize all patients but perform a separate analysis on the biomarker-positive patients or only randomize marker-positive patients after the run-in period. We evaluate the proposed design compared with the conventional phase III design and discuss how to design a run-in trial based on phase II studies.

RESULTS

The proposed design achieves a major sample size reduction compared with the conventional randomized phase III design in many cases when the biomarker has good sensitivity (≥0.7) and specificity (≥0.7). This requires that the biomarker be measured accurately and be indicative of drug activity. However, the proposed design loses some of its advantage when the proportion of potential responders is large (>50%) or the effect on survival from run-in period is substantial.

CONCLUSIONS

Incorporating a pharmacodynamic biomarker requires careful consideration but can expand the capacity of clinical trials to personalize treatment decisions and enhance therapeutics development.

BTG2 inhibits the proliferation, invasion, and apoptosis of MDA-MB-231 triple-negative breast cancer cells

The purposes of this study were to investigate the effects of B cell translocation gene 2 (BTG2) on the proliferation, apoptosis, and invasion of triple-negative breast cancer and to provide an experimental basis for the future treatment of human triple-negative breast cancer. A pcDNA3.1-BTG2 eukaryotic expression vector was constructed and transfected into the MDA-MB-231 human triple-negative breast cancer cell line using lipofection. Then, relevant changes in the biological characteristics of the BTG2-expressing cell line were analyzed using MTT (tetrazolium blue), flow cytometry, and Transwell invasion chamber assays. Additionally, the effects of BTG2 expression on cyclin D1, caspase 3, and matrix metalloproteinases 1/2 (MMP-1/-2) expression were analyzed. Cell proliferation was significantly lower in the pcDNA3.1-BTG2-transfected group compared to the empty vector and blank control groups (p<0.05). There was no significant difference between the empty vector and blank control groups. FCM results demonstrated that there were significantly more cells in the G1 phase of the cell cycle and fewer S phase cells in the pcDNA3.1-BTG2 group than in the empty vector and blank control groups (p<0.05). Additionally, the proportion of cells that migrated across the membrane was significantly lower in the pcDNA3.1-BTG2 group than in the empty vector and blank control groups (p<0.05). Cyclin D1 and MMP-1/-2 expression were significantly lower in MDA-MB-231 cells transfected with pcDNA3.1-BTG2 as compared to the empty vector and blank control groups (p<0.05). Caspase 3 expression was significantly higher in MDA-MB-231 cells from the pcDNA3.1-BTG2 group compared to the empty vector and blank control groups (p<0.05). In conclusion, BTG2 may inhibit MDA-MB-231 proliferation and promote apoptosis. Additionally, BTG2 may also inhibit the invasion of MDA-MB-231 human triple-negative breast cancer cells.

Down-regulation of SENP1 expression increases apoptosis of Burkitt lymphoma cells

OBJECTIVE

To investigate the effect of down-regulation of Sentrin/SUMO-specific protease 1 (SENP1) expression on the apoptosis of human Burkitt lymphoma cells (Daudi cells) and potential mechanisms.

METHODS

Short hairpin RNA (shRNA) targeting SENP1 was designed and synthesized and then cloned into a lentiviral vector. A lentiviral packaging plasmid was used to transfect Daudi cells (sh-SENP1-Daudi group). Daudi cells without transfection (Daudi group) and Daudi cells transfected with blank plasmid (sh-NC-Daudi group) served as control groups. Flow cytometry was performed to screen GFP positive cells and semiquantitative PCR and Western blot assays were employed to detect the inference efficiency. The morphology of cells was observed under a microscope before and after transfection. Fluorescence quantitative PCR and Western blot assays were conducted to measure the mRNA and protein expression of apoptosis related molecules (caspase-3, 8 and 9). After treatment with COCl2 for 24 h, the mRNA and protein expression of hypoxia inducible factor -1α (HIF-1α) was determined.

RESULTS

Sequencing showed the expression vectors of shRNA targeting SENP1 to be successfully constructed. Following screening of GFP positive cells by FCM, semiqualitative PCR showed the interference efficiency was 79.2±0.026%. At 48 h after transfection, the Daudi cells became shrunken, had irregular edges and presented apoptotic bodies. Western blot assay revealed increase in expression of caspase-3, 8 and 9 with prolongation of transfection (P<0.05). Following hypoxia treatment, mRNA expression of HIF-1α remained unchanged in three groups (P>0.05) but the protein expression of HIF-1α markedly increased (P<0.05). However, in the sh-SENP1-Daudi group, the protein expression of HIF-1α remained unchanged.

CONCLUSION

SENP1-shRNA can efficiently inhibit SENP1 expression in Daudi cells. SENP1 inhibition may promote cell apoptosis. These findings suggest that SENP1 may serve as an important target in the gene therapy of Burkitts lymphoma.

The tyrosine kinase inhibitor E-3810 combined with paclitaxel inhibits the growth of advanced-stage triple-negative breast cancer xenografts

E-3810 is a novel small molecule that inhibits VEGF receptor-1, -2, and -3 and fibroblast growth factor receptor-1 tyrosine kinases at nmol/L concentrations currently in phase clinical II. In preclinical studies, it had a broad spectrum of antitumor activity when used as monotherapy in a variety of human xenografts. We here investigated the activity of E-3810 combined with different cytotoxic agents in a MDA-MB-231 triple-negative breast cancer xenograft model. The molecule could be safely administered with 5-fluorouracil, cisplatin, and paclitaxel. The E-3810-paclitaxel combination showed a striking activity with complete, lasting tumor regressions; the antitumor activity of the combination was also confirmed in another triple-negative breast xenograft, MX-1. The activity was superior to that of the combinations paclitaxel+brivanib and paclitaxel+sunitinib. Pharmacokinetics studies suggest that the extra antitumor activity of the combination is not due to higher paclitaxel tumor levels, which in fact were lower in mice pretreated with all three kinase inhibitors, and the paclitaxel plasma levels excluded reduced drug availability. Pharmacodynamic studies showed that E-3810, brivanib, and sunitinib given as single agents or in combination with paclitaxel reduced the number of vessels, but did not modify vessel maturation. Reduced tumor collagen IV and increased plasma collagen IV, associated with increased matrix metalloproteinases (MMP), particularly host MMP-9, indicate a proteolytic remodeling of the extracellular matrix caused by E-3810 that in conjunction with the cytotoxic effect of paclitaxel on the tumor cells (caspase-3/7 activity) may contribute to the striking activity of their combination. These data support the therapeutic potential of combining E-3810 with conventional chemotherapy.

The effects of RKIP gene expression on the biological characteristics of human triple-negative breast cancer cells in vitro

The purpose of this study was to investigate the effect of Raf kinase inhibitor protein (RKIP) on the growth, proliferation, invasion and metastasis of triple-negative breast cancer (TNBC) cells to provide experimental evidence for developing future therapies against human TNBC. The pcDNA3.1-RKIP eukaryotic expression vector was constructed and transfected into the TNBC cell line MDA-MB-231. The alterations of the biological characteristics of RKIP-transfected MDA-MB-231 cells were analyzed using the following approaches: a growth curve, a 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT) assay, bromodeoxyuridine (BrdU) staining and a cell migration assay. The effects of the RKIP gene on MMP-1 and MMP-2 expression were also examined. The pcDNA3.1 empty vector-transfected and mock-transfected MDA-MB-231 cells were used as control groups. Compared with the empty vector-transfected and mock-transfected cells, the cell growth of RKIP-transfected MDA-MB-231 cells was significantly reduced. The empty vector-transfected group was not significantly different compared with the mock-transfected MDA-MB-231 cells. The results of the MTT and BrdU assays demonstrated that the proliferation of pcDNA3.1-RKIP-transfected cells was significantly reduced compared to the control cells (P < 0.05). The result of the cell migration assay suggested that the cross-membrane migration rate of the pcDNA3.1-RKIP-transfected cells was significantly lower than that of the control MDA-MB-231 cells (P < 0.05). We also demonstrated that RKIP may inhibit MMP-1 and MMP-2 expression in MDA-MB-231 cells. The RKIP gene may play a role in inhibiting cellular proliferation. The RKIP gene may also have some inhibitory effects on the invasiveness and metastatic capability of human TNBC cells.

Hypoxia-inducible factor 1α promotes primary tumor growth and tumor-initiating cell activity in breast cancer

Introduction

Overexpression of the oxygen-responsive transcription factor hypoxia-inducible factor 1α (HIF-1α) correlates with poor prognosis in breast cancer patients. The mouse mammary tumor virus polyoma virus middle T (MMTV-PyMT) mouse is a widely utilized preclinical mouse model that resembles human luminal breast cancer and is highly metastatic. Prior studies in which the PyMT model was used demonstrated that HIF-1α is essential to promoting carcinoma onset and lung metastasis, although no differences in primary tumor end point size were observed. Using a refined model system, we investigated whether HIF-1α is directly implicated in the regulation of tumor-initiating cells (TICs) in breast cancer.

Methods

Mammary tumor epithelial cells were created from MMTV-PyMT mice harboring conditional alleles of Hif1a, followed by transduction ex vivo with either adenovirus β-galactosidase or adenovirus Cre to generate wild-type (WT) and HIF-1α-null (KO) cells, respectively. The impact of HIF-1α deletion on tumor-initiating potential was investigated using tumorsphere assays, limiting dilution transplantation and gene expression analysis.

Results

Efficient deletion of HIF-1α reduced primary tumor growth and suppressed lung metastases, prolonging survival. Loss of HIF-1α led to reduced expression of markers of the basal lineage (K5/K14) in cells and tumors and of multiple genes involved in the epithelial-to-mesenchymal transition. HIF-1α also enhanced tumorsphere formation at normoxia and hypoxia. Decreased expression of several genes in the Notch pathway as well as Vegf and Prominin-1 (CD133)was observed in response to Hif1a deletion. Immunohistochemistry confirmed that CD133 expression was reduced in KO cells and in tumorspheres. Tumorsphere formation was enhanced in CD133^hi versus CD133^neg cells sorted from PyMT tumors. Limiting dilution transplantation of WT and KO tumor cells into immunocompetent recipients revealed > 30-fold enrichment of TICs in WT cells.

Conclusion

These results demonstrate that HIF-1α plays a key role in promoting primary mammary tumor growth and metastasis, in part through regulation of TICs. HIF-1α regulates expression of several members of the Notch pathway, CD133 and markers of the basal lineage in mammary tumors. Our results suggest that CD133, which has not been profiled extensively in breast cancer, may be a useful marker of TICs in the PyMT mouse model. These data reveal for the first time that HIF-1α directly regulates breast TIC activity in vivo.