Strategies for the discovery and development of therapies for metastatic breast cancer

Synthesis and in vitro study of modified chitosan-polycaprolactam nanocomplex as delivery system

In this work, chitosan/polycaprolactam (PCL-CS) nano-complex was synthesized and their micelles were formed as self-assembled amphiphilic nano-compartments. These micelles were utilize for drug delivery after loading quercetin (QU) as chemotherapeutic agent and delivery potency of this nano-complex was investigated. This nano-complex was also functionalized with folic acid (FA) in order to targeting delivery of nano-carrier to cancer cell lines. This foure dimensional nano-complex was successfully characterized based on UV-vis, FT-IR, DLS, and TGA analytical devices to confirm the synthesis. Drug loading was estimated 21.5% in final nano-carrier. In vitro drug release study was applied to investigation of QU release in PBS that was exhibited high potency of nano-complex in controlled drug release. Cell viability of assay was implemented to determination of biocompatibility, bioavailability and therapeutic potency of nano-complexes on different cancer and normal cell lines. Micelles demonstrated safety levels for 24 and 48 h post-treatment incubation and FA receptor mediated uptake of chitosan/polycaprolactam/folic acid/quercetin (PCL-CS-FA-QU) was exhibited excellent efficiency on inhibition of cancer cells.

Breast cancer lung metastasis: Molecular biology and therapeutic implications

Distant metastasis accounts for the vast majority of deaths in patients with cancer. Breast cancer exhibits a distinct metastatic pattern commonly involving bone, liver, lung, and brain. Breast cancer can be divided into different subtypes based on gene expression profiles, and different breast cancer subtypes show preference to distinct organ sites of metastasis. Luminal breast tumors tend to metastasize to bone while basal-like breast cancer (BLBC) displays a lung tropism of metastasis. However, the mechanisms underlying this organ-specific pattern of metastasis still remain to be elucidated. In this review, we will summarize the recent advances regarding the molecular signaling pathways as well as the therapeutic strategies for treating breast cancer lung metastasis.

Detection of Cancer DNA in Early Stage and Metastatic Breast Cancer Patients

Breast cancer is the leading cause of cancer in women and the second leading cause of cancer-related death. There are many subtypes of breast cancer, which can be identified through the process of molecular and genetic profiling. While the current standard of care utilizes tumor tissue biopsy to subclassify breast cancer, plasma tumor DNA (ptDNA) can be detected through droplet digital PCR (ddPCR) of plasma obtained from a simple blood draw. Tissue biopsy is not only more invasive but because tumors exhibit heterogeneity it can be less accurate. Blood collects DNA shed from normal and cancerous cells alike, thus ddPCR of plasma offers a broader picture of a cancer's genetic makeup. This chapter summarizes how patients with breast cancer can be screened for specific cancerous mutations in both tissue and plasma through the use of ddPCR.

Co-delivery of docetaxel and silibinin using pH-sensitive micelles improves therapy of metastatic breast cancer

Breast cancer is the most vicious killer for women, and tumor metastasis is one of the leading causes of breast cancer therapy failure. In this study, a new pH-sensitive polymer (polyethylene glycol-block-poly[(1,4-butanediol)-diacrylate-β-N,N-diisopropylethylenediamine], BDP) was synthesized. Based on BDP, docetaxel/silibinin co-delivery micelles (DSMs) was constructed. DSM had a well-defined spherical shape under the transmission electron microscope with average hydrodynamic diameter of 85.3±0.4 nm, and were stable in the bloodstream but could dissociate to release the chemotherapeutic agents in the low pH environment of the endo/lysosomes in the tumor cells. Compared with free drugs, DSM displayed greatly enhanced cellular uptake, higher cytotoxicity and a stronger anti-metastasis effect against mouse breast cancer cell line 4T1. In 4T1 tumor-bearing mice treated with DSM (twice a week for 3 weeks), the inhibition rate on tumor growth and metastasis reached 71.9% and 80.1%, respectively. These results reveal that DSM might be a promising drug delivery system for metastatic breast cancer therapy.

Beyond the vicious cycle: The role of innate osteoimmunity, automimicry and tumor-inherent changes in dictating bone metastasis

Bone metastasis is a fatal consequence of a subset of solid malignancies that fail to respond to conventional therapies. While a myriad of factors contribute to osteotropism and disseminated cell survival and outgrowth in bone, efforts to inhibit tumor cell growth in the bone-metastatic niche have largely relied on measures that disrupt the bi-directional interactions between bone resident and tumor cells. However, the targeting of isolated stromal interactions has proven ineffective to date in inhibiting bone-metastatic progression and patient mortality. Osteoimmune regulation is now emerging as a critical determinant of metastatic growth in the bone microenvironment. While this has highlighted the importance of innate immune populations in dictating the temporal development of overt bone metastases, the osteoimmunological processes that underpin tumor cell progression in bone remain severely underexplored. Along with tumor-intrinsic alterations that occur specifically within the bone microenvironment, innate osteoimmunological crosstalk poses an exciting area of future discovery and therapeutic development. Here we review current knowledge of the unique exchange that occurs between bone resident cells, innate immune populations and tumor cells that leads to the establishment of a tumor-permissive milieu.

In vivo validation of metastasis-regulating microRNA-766 in human triple-negative breast cancer cells

Breast cancer is the second most common cancer and the most frequent cancer in women worldwide. Recent improvements in early detection and effective adjuvant chemotherapies have improved the survival of breast cancer patients. Even with initial disease remission, one-third of all breast cancer patients will relapse with distant metastasis. Breast cancer metastasis is largely an incurable disease and the main cause of death among breast cancer patients. Cancer metastasis is comprised of complex processes that are usually not controllable by intervention of a single molecular target. As a single microRNA (miRNA) can affect the aggressiveness of breast cancer cells by concurrently modulating multiple pathway effectors, a metastasis-regulating miRNA would represent a good disease target candidate. In this study, we evaluated the functional capacity of a newly defined human metastasis-related miRNA, miR-766, which was previously identified by comparing a patient-derived xenograft primary tumor model and a metastasis model. Compared to vector-transfected control cells, miR-766-overexpressed triple-negative breast cancer cells exhibited similar primary tumor growth in the orthotopic xenograft model. In contrast, tumor sphere formation and Matrigel invasion were significantly decreased in miR-766-overexpressed breast cancer cells compared with control cancer cells. In addition, lung metastasis was dramatically reduced in miR-766-overexpressed breast cancer cells compared with control cells. Thus, miR-766 affected the distant metastasis process to a greater extent than cancer cell proliferation and primary tumor growth, and may represent a future therapeutic target to effectively control fatal breast cancer metastasis.

Crotonis Fructus Extract Inhibits 12-O-Tetradecanoylphorbol-13-Acetate-Induced Expression of Matrix Metalloproteinase-9 via the Activator Protein-1 Pathway in MCF-7 Cells

Purpose

Metastatic cancers spread from the primary site of origin to other parts of the body. Matrix metalloproteinase-9 (MMP-9) is essential in metastatic cancers owing to its major role in cancer cell invasion. Crotonis fructus (CF), the mature fruits of Croton tiglium L., have been used for the treatment of gastrointestinal disturbance in Asia. In this study, the effect of the ethanol extract of CF (CFE) on MMP-9 activity and the invasion of 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated MCF-7 cells was examined.

Methods

The cell viability was evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. The expression of MMP-9 was examined by Western blotting, zymography, and real-time polymerase chain reaction. An electrophoretic mobility gel shift assay was performed to detect activator protein-1 (AP-1) DNA binding activity and cell invasiveness was measured by an in vitro Matrigel invasion assay.

Results

CFE significantly suppressed MMP-9 expression and activation in a dose-dependent manner. Furthermore, CFE attenuated the TPA-induced activation of AP-1.

Conclusion

The results indicated that the inhibitory effects of CFE against TPA-induced MMP-9 expression and MCF-7 cell invasion were dependent on the protein kinase C δ/p38/c-Jun N-terminal kinase/AP-1 pathway. Therefore, CFE could restrict breast cancer invasiveness owing to its ability to inhibit MMP-9 activity.

Inflammatory Monocytes Loading Protease-Sensitive Nanoparticles Enable Lung Metastasis Targeting and Intelligent Drug Release for Anti-Metastasis Therapy

Metastasis causes high mortality of breast cancer, and the inability of drug delivery to metastatic sites remains a crucial challenge for antimetastasis therapy. Herein, we report that inflammatory monocytes loading legumain-activated nanoparticles can actively target lung metastases and initiate metastasis-specific intelligent drug release for antimetastasis therapy. The cytotoxic mertansine is conjugated to poly(styrene-co-maleic anhydride) with a legumain-sensitive peptide and self-assembled into nanoparticles (SMNs), and then loaded into inflammatory monocytes to prepare the SMNs-loaded monocytes delivery system (M-SMNs). M-SMNs would be in living state in circulation to ensure their active targeting to lung metastases, and responsively damaged at the metastatic sites upon the differentiation of monocytes into macrophages. The anticancer drugs are intelligently released from M-SMNs as free drug molecules and drug-loaded microvesicles, resulting in considerable inhibition on the proliferation, migration, and invasion activities of metastatic 4T1 breast cancer cells. Moreover, M-SMNs significantly improve the delivery to lung metastases and penetrate the metastatic tumors, thus producing a 77.8% inhibition of lung metastases. Taken together, our findings provide an intelligent biomimetic drug delivery strategy via the biological properties of inflammatory monocytes for effective antimetastasis therapy.

Prevention of breast cancer skeletal metastases with parathyroid hormone

Advanced breast cancer is frequently associated with skeletal metastases and accelerated bone loss. Recombinant parathyroid hormone [teriparatide, PTH(1-34)] is the first anabolic agent approved in the US for treatment of osteoporosis. While signaling through the PTH receptor in the osteoblast lineage regulates bone marrow hematopoietic niches, the effects of anabolic PTH on the skeletal metastatic niche are unknown. Here, we demonstrate, using orthotopic and intratibial models of 4T1 murine and MDA-MB-231 human breast cancer tumors, that anabolic PTH decreases both tumor engraftment and the incidence of spontaneous skeletal metastasis in mice. Microcomputed tomography and histomorphometric analyses revealed that PTH increases bone volume and reduces tumor engraftment and volume. Transwell migration assays with murine and human breast cancer cells revealed that PTH alters the gene expression profile of the metastatic niche, in particular VCAM-1, to inhibit recruitment of cancer cells. While PTH did not affect growth or migration of the primary tumor, it elicited several changes in the tumor gene expression profile resulting in a less metastatic phenotype. In conclusion, PTH treatment in mice alters the bone microenvironment, resulting in decreased cancer cell engraftment, reduced incidence of metastases, preservation of bone microarchitecture and prolonged survival.

Human antigen R-regulated CCL20 contributes to osteolytic breast cancer bone metastasis

Breast cancer mainly spreads to bone, causing decreased survival of patient. Human antigen R (HuR) and chemokines are important molecules associated with mRNA stability and cell-cell interaction in cancer biology. Here, HuR knockdown inhibited bone metastasis and osteolysis of metastatic breast cancer cells in mice and HuR expression promoted the metastatic ability of cancer cells via CCL20 and GM-CSF. In contrast with the findings for GM-CSF, ELAVL1 and CCL20 expressions were markedly increased in breast tumor tissues and ELAVL1 expression showed a strong positive correlation with CCL20 expression in breast cancer subtypes, particularly the basal-like subtype. Metastasis-free survival and overall survival were decreased in the breast cancer patients with high CCL20 expression. We further confirmed the role of CCL20 in breast cancer bone metastasis. Intraperitoneal administration of anti-CCL20 antibodies inhibited osteolytic breast cancer bone metastasis in mice. Treatment with CCL20 noticeably promoted cell invasion and the secretion of MMP-2/9 in the basal-like triple-negative breast cancer cell lines, not the luminal. Moreover, CCL20 elevated the receptor activator of nuclear factors kappa-B ligand/osteoprotegerin ratio in breast cancer and osteoblastic cells and mediated the crosstalk between these cells. Collectively, HuR-regulated CCL20 may be an attractive therapeutic target for breast cancer bone metastasis.

Neoadjuvant Interferons: Critical for Effective PD-1-Based Immunotherapy in TNBC

The lack of targeted therapies available for triple-negative breast cancer (TNBC) patients who fail to respond to first-line chemotherapy has sparked interest in immunotherapeutic approaches. However, trials utilizing checkpoint inhibitors targeting the PD-1/PD-L1 axis in TNBC have had underwhelming responses. Here, we investigated the interplay between type I IFN signaling and the PD-1/PD-L1 axis and tested the impact of combining IFN inducers, as immune activators, with anti-PD-1, to induce an antimetastatic immune response. Using models of TNBC, we demonstrated an interplay between type I IFN signaling and tumor cell PD-L1 expression that affected therapeutic response. The data revealed that the type I IFN-inducer poly(I:C) was an effective immune activator and antimetastatic agent, functioning better than anti-PD-1, which was ineffective as a single agent. Poly(I:C) treatment induced PD-L1 expression on TNBC cells, and combined poly(I:C) and anti-PD-1 treatment prolonged metastasis-free survival in a neoadjuvant setting via the induction of a tumor-specific T-cell response. Use of this combination in a late treatment setting did not impact metastasis-free survival, indicating that timing was critical for immunotherapeutic benefit. Together, these data demonstrated anti-PD-1 as an ineffective single agent in preclinical models of TNBC. However, type I IFN inducers were effective immune activators, and neoadjuvant trials combining them with anti-PD-1 to induce a sustained antitumor immune response are warranted. Cancer Immunol Res; 5(10); 871-84. ©2017 AACR.

PAD1 promotes epithelial-mesenchymal transition and metastasis in triple-negative breast cancer cells by regulating MEK1-ERK1/2-MMP2 signaling

Peptidylargininedeiminase 1 (PAD1) catalyzes protein for citrullination, and this activity has been linked to the epidermal cornification. However, a role for PAD1 in tumorigenesis, including breast cancers has not been previously explored. Here we first showed that PAD1 is overexpressed in human triple negative breast cancer (TNBC). In cultured cells and xenograft mouse models, PAD1 depletion or inhibition reduced cell proliferation, suppressed epithelial-mesenchymal transition, and prevented metastasis of MDA-MB-231 cells. These changes were correlated with a dramatic decrease in MMP2/9 expression. Furthermore, ERK1/2 and P38 MAPK signaling pathways are activated upon PAD1 silencing. Treatment with MEK1/2 inhibitor in PAD1 knockdown cells significantly recovered MMP2 expression, while inhibiting P38 activation only slightly elevated MMP9 levels. We then showed that PAD1 interacts with and citrullinates MEK1 thereby disrupting MEK1-catalyzed ERK1/2 phosphorylation, thus leading to the MMP2 overexpression. Collectively, our data indicate that PAD1 appears to promote tumorigenesis by regulating MEK1-ERK1/2-MMP2 signaling in TNBC. These results also raise the possibility that PAD1 may function as an important new biomarker for TNBC tumors and suggest that PAD1-specific inhibitors could potentially be utilized to treat metastatic breast cancer.

MicroRNA-519a-3p mediates apoptosis resistance in breast cancer cells and their escape from recognition by natural killer cells

Aggressive breast cancer is associated with poor patient outcome and characterized by the development of tumor cell variants that are able to escape from control of the immune system or are resistant to targeted therapies. The complex molecular mechanisms leading to immune escape and therapy resistance are incompletely understood. We have previously shown that high miR-519a-3p levels are associated with poor survival in breast cancer. Here, we demonstrate that miR-519a-3p confers resistance to apoptosis induced by TRAIL, FasL and granzyme B/perforin by interfering with apoptosis signaling in breast cancer cells. MiR-519a-3p diminished the expression of its direct target genes for TRAIL-R2 (TNFRSF10B) and for caspase-8 (CASP8) and its indirect target gene for caspase-7 (CASP7), resulting in reduced sensitivity and tumor cell apoptosis in response to apoptotic stimuli. Furthermore, miR-519a-3p impaired tumor cell killing by natural killer (NK) cells via downregulation of the NKG2D ligands ULBP2 and MICA on the surface of tumor cells that are crucial for the recognition of these tumor cells by NK cells. We determined that miR-519a-3p was overexpressed in more aggressive mutant TP53 breast cancer that was associated with poor survival. Furthermore, low levels of TRAIL-R2, caspase-7 and caspase-8 correlated with poor survival, suggesting that the inhibitory effect of miR-519a-3p on TRAIL-R2 and caspases may have direct clinical relevance in lowering patient’s prognosis. In conclusion, we demonstrate that miR-519a-3p is a critical factor in mediating resistance toward cancer cell apoptosis and impairing tumor cell recognition by NK cells. This joint regulation of apoptosis and immune cell recognition through miR-519a-3p supports the hypothesis that miRNAs are key regulators of cancer cell fate, facilitating cancer progression and evasion from immunosurveillance at multiple and interconnected levels.

Synthesis and anticancer properties of ruthenium (II) complexes as potent apoptosis inducers through mitochondrial disruption

A new ligand MHPIP (MHPIP = 2-(1-methyl-1H-pyrazol-4-yl)-1H-imidazo[4,5-f][1,10]phenanthroline) and its three ruthenium (II) complexes [Ru(N-N)₂(MHPIP)](ClO₄)₂ (N-N = phen: 1,10-phenanthroline 1; dmp = 2,9-dimethyl-1,10-phenanthroline 2; ttbpy = 4,4'-ditertiarybutyl-2,2'-bipyridine 3) were synthesized and characterized. The cytotoxic activity in vitro was studied by MTT method. The complexes 1-3 show moderate cytotoxic effects on the cell growth in HepG2 cells with an IC₅₀ value of 25.5 ± 3.5, 35.6 ± 1.9 and 27.4 ± 2.3 μM, respectively. The apoptosis was investigated with AO/EB and Annex V/PI staining methods and comet assay. The reactive oxygen species, mitochondrial membrane potential were investigated under a fluorescent microscope. Autophagy assay shows that the complexes can cause autophagy and up-regulate the expression of Beclin-1 protein. Additionally, the complexes inhibit the cell growth in HepG2 cells at G0/G1 phase, and the complexes can regulate the expression of caspase 3 and Bcl-2 family proteins. The studies demonstrate that the complexes induce apoptosis in HepG2 cells through DNA damage and ROS-mediated mitochondrial dysfunction pathways.

Effect of Sorbus commixta on the invasion and migration of human hepatocellular carcinoma Hep3B cells

Tumor metastasis is a main cause of cancer-related morbidity and mortality. Thus, a number of medicinal herbs and phytochemicals have been investigated as possible candidates for the inhibition of cancer metastasis. Sorbus commixta Hedl. (SC) is a traditional medicinal plant used in the treatment of inflammatory diseases, as it has antioxidant, anti-inflammatory, anti-atherosclerotic and anti-hepatotoxic activities. In this study, we demonstrate that the water extract of SC exerts inhibitory effect on the invasion and migration of hepatocellular carcinoma Hep3B cells. The activity and expression of matrix metalloproteinase (MMP)-9, which is responsible for the invasion of cancer cells, was decreased by SC treatment. The invasive and migratory potentials of the Hep3B cells were also decreased, as evidence by in vitro assay using the Boyden chamber system. In addition, the expression of the chemokine receptors, C-X-C chemokine receptor type 4 (CXCR)4 and C-X-C chemokine receptor type 6 (CXCR6), were inhibited by SC in Hep3B cells. Furthermore, actin fiber organization was markedly suppressed by SC treatment. Taken together, the findings of this study suggest for the first time, to the best of our knowledge, that SC suppresses the invasion and migration of highly metastatic Hep3B cells.

Treating breast cancer metastasis with cabazitaxel-loaded polymeric micelles

Cancer metastasis is the primary cause of high mortality in breast cancer patients. In this study, we loaded an anti-cancer drug, cabazitaxel (CTX), into polymeric micelles (CTX-loaded polymeric micelles, PCMs), and explored their therapeutic efficacy in breast cancer metastasis. The characteristics of PCMs were investigated, and their anti-metastatic efficacy was assessed using in vitro and in vivo evaluations. PCMs had an average diameter of 50.13±11.96 nm with a CTX encapsulation efficiency of 97.02%±0.97%. PCMs could be effectively internalized into metastatic 4T1 breast cancer cells in vitro. CTX (10 ng/mL) or an equivalent concentration in PCMs did not significantly affected the viability of 4T1 cells, but dramatically decreased the cell migration activities. In an orthotopic metastatic breast cancer model, intravenously administered PCMs could be efficiently delivered to the tumor sites, resulting in a 71.6% inhibition of tumor growth and a 93.5% reduction of lung metastases. Taken together, our results verify the anti-metastatic efficacy of PCMs, thus providing an encouraging strategy for treating breast cancer metastasis.

Cooperation among heterogeneous prostate cancer cells in the bone metastatic niche

The growth of disseminated tumor cells into metastatic lesions depends on the establishment of a favorable microenvironment in the stroma of the target organs. Here we show that mice treated with anakinra, an antagonist of the interleukin (IL)-1β receptor (IL-1R), or harboring a targeted deletion of IL-1R are significantly less prone to develop bone tumors when inoculated in the arterial circulation with human prostate cancer (PCa) cells expressing IL-1β. Interestingly, human mesenchymal stem cells exposed in vitro to medium conditioned by IL-1β-expressing cancer cells responded by upregulating S100A4, a marker of cancer-associated fibroblasts (CAFs), and this effect was blocked by anakinra. Analogously, the stroma adjacent to skeletal metastases generated in mice by IL-1β-expressing cancer cells showed a dramatic increase in S100A4, COX-2 and the alteration of 30 tumor-related genes as measured by Nanostring analysis. These effects were not observed in the stroma associated with the rare and much smaller metastases generated by the same cells in IL-1R knockout animals, confirming that tumor-secreted IL-1β generates skeletal CAFs and conditions the surrounding bone microenvironment. In skeletal lesions from patients with metastatic PCa, histological and molecular analyses revealed that IL-1β is highly expressed in cancer cells in which the androgen receptor (AR) is not detected (AR-), whereas this cytokine is uniformly absent in the AR-positive (AR+) metastatic cells. The stroma conditioned by IL-1β-expressing cancer cells served as a supportive niche also for coexisting IL-1β-lacking cancer cells, which are otherwise unable to generate tumors after independently seeding the skeleton of mice. This niche is established very early following tumor seeding and hints to a role of IL-1β in promoting early colonization of PCa at the skeletal level.

Methylene blue photodynamic therapy induces selective and massive cell death in human breast cancer cells

BACKGROUND

Breast cancer is the main cause of mortality among women. The disease presents high recurrence mainly due to incomplete efficacy of primary treatment in killing all cancer cells. Photodynamic therapy (PDT), an approach that causes tissue destruction by visible light in the presence of a photosensitizer (Ps) and oxygen, appears as a promising alternative therapy that could be used adjunct to chemotherapy and surgery for curing cancer. However, the efficacy of PDT to treat breast tumours as well as the molecular mechanisms that lead to cell death remain unclear.

METHODS

In this study, we assessed the cell-killing potential of PDT using methylene blue (MB-PDT) in three breast epithelial cell lines that represent non-malignant conditions and different molecular subtypes of breast tumours. Cells were incubated in the absence or presence of MB and irradiated or not at 640 nm with 4.5 J/cm2. We used a combination of imaging and biochemistry approaches to assess the involvement of classical autophagic and apoptotic pathways in mediating the cell-deletion induced by MB-PDT. The role of these pathways was investigated using specific inhibitors, activators and gene silencing.

RESULTS

We observed that MB-PDT differentially induces massive cell death of tumour cells. Non-malignant cells were significantly more resistant to the therapy compared to malignant cells. Morphological and biochemical analysis of dying cells pointed to alternative mechanisms rather than classical apoptosis. MB-PDT-induced autophagy modulated cell viability depending on the cell model used. However, impairment of one of these pathways did not prevent the fatal destination of MB-PDT treated cells. Additionally, when using a physiological 3D culture model that recapitulates relevant features of normal and tumorous breast tissue morphology, we found that MB-PDT differential action in killing tumour cells was even higher than what was detected in 2D cultures.

CONCLUSIONS

Finally, our observations underscore the potential of MB-PDT as a highly efficient strategy which could use as a powerful adjunct therapy to surgery of breast tumours, and possibly other types of tumours, to safely increase the eradication rate of microscopic residual disease and thus minimizing the chance of both local and metastatic recurrence.

Incorporating gold nanoclusters and target-directed liposomes as a synergistic amplified colorimetric sensor for HER2-positive breast cancer cell detection

Breast cancer is the second leading cause of cancer-related mortality in women. Successful development of sensitive nanoprobes for breast cancer cell detection is of great importance for breast cancer diagnosis and symptomatic treatment. Herein, inspired by the intrinsic peroxidase property of gold nanoclusters, high loading, and targeting ability of ErbB2/Her2 antibody functionalized liposomes, we report that gold nanoclusters-loaded, target-directed, functionalized liposomes can serve as a robust sensing platform for amplified colorimetric detection of HER2-positive breast cancer cells. This approach allows HER2-positive breast cancer cell identification at high sensitivity with high selectivity. In addition, the colorimetric “readout” offers extra advantages in terms of low-cost, portability, and easy-to-use applications. The practicality of this platform was further proved by successful detection of HER2-positive breast cancer cells in human serum samples and in breast cancer tissue, which indicated our proposed method has potential for application in cancer theranostics.

Gold Nanospheres-Stabilized Indocyanine Green as a Synchronous Photodynamic-Photothermal Therapy Platform That Inhibits Tumor Growth and Metastasis

Both photothermal therapy (PTT) and photodynamic therapy (PDT) are phototherapeutic approaches, which have been widely investigated for cancer therapy mediated by an external light source. Here, a nanosystem presenting the synchronous PTT and PDT effect realized through one-step near-infrared (NIR) light irradiation is reported. This system was fabricated by conjugating indocyanine green (ICG) on hollow gold nanospheres (HAuNS) using branched-polyethylenimine (PEI, MW = 10 kDa) as optimal linker, which provided a high ICG payload as well as a covering layer with suitable thickness on HAuNS to maintain ICG fluorescence and reactive oxygen species (ROS) productivity. The resulting system (ICG-PEI-HAuNS) had the molar ratio of ICG:PEI:Au = 3:0.33:5. Compared with free ICG, ICG-PEI-HAuNS exhibited dramatically enhanced stability of ICG molecules and greater intratumoral accumulation. The conjugation of ICG caused significantly higher plasmon absorption of ICG-PEI-HAuNS in the NIR region compared with HAuNS alone, inducing remarkably enhanced photothermal conversion efficiency and synchronous photodynamic effect under NIR light irradiation. Interestingly, compared with PTT or PDT alone, synchronous PTT and PDT produced by ICG-PEI-HAuNS upon NIR light irradiation induced significantly stronger antitumor and metastasis inhibition effects both in vitro and in vivo, which might be a promising strategy for cancer treatment.

Doxorubicin and siRNA Codelivery via Chitosan-Coated pH-Responsive Mixed Micellar Polyplexes for Enhanced Cancer Therapy in Multidrug-Resistant Tumors

This study investigated the potential of chitosan-coated mixed micellar nanocarriers (polyplexes) for codelivery of siRNA and doxorubicin (DOX). DOX-loaded mixed micelles (serving as cores) were prepared by thin film hydration method and coated with chitosan (CS, serving as outer shell), and complexed with multidrug resistance (MDR) inhibiting siRNA. Selective targeting was achieved by folic acid conjugation. The polyplexes showed pH-responsive enhanced DOX release in acidic tumor pH, resulting in higher intracellular accumulation, which was further augmented by downregulation of mdr-1 gene after treatment with siRNA-complexed polyplexes. In vitro cytotoxicity assay demonstrated an enhanced cytotoxicity in native 4T1 and multidrug-resistant 4T1-mdr cell lines, compared to free DOX. Furthermore, in vivo, polyplexes codelivery resulted in highest DOX accumulation and significantly reduced the tumor volume in mice with 4T1 and 4T1-mdr tumors as compared to the free DOX groups, leading to improved survival times in mice. In conclusion, codelivery of siRNA and DOX via polyplexes has excellent potential as targeted drug nanocarriers for treatment of MDR cancers.

Safflower Yellow Prevents Pulmonary Metastasis of Breast Cancer by Inhibiting Tumor Cell Invadopodia

Carthamus tinctorius L. is a traditional Chinese medicine that activates blood circulation and dissipates blood stasis, and has been extensively used as antitumor treatment in a clinical setting in single or in compound preparation form. However, empirical evidence and a better understanding of the possible mechanisms involved are still required. Here, we investigated the role of safflower yellow (SY), the active ingredient of C. tinctorius, in the pulmonary metastasis of breast cancer, and the underlying mechanism of action. EGF-meditated time- and dose-dependent cell response profiles were applied to screen for the activity of SY in vitro, while orthotopic lung metastasis and intravenous injection were used to evaluate the antimetastatic role of SY in vivo. SY could dose-dependently inhibit EGF-mediated time- and dose-dependent cell response profiles by inhibiting cytoskeletal rearrangement. We also found that SY significantly inhibited the migration of breast cancer cells in vitro and pulmonary metastasis of breast cancer cells in vivo. Consistent with these phenotypes, formation of invadopodia and the expression of MMP-9 and p-Src proteins were decreased after EGF stimulation in MBA-MD-231 cells treat with SY, as well as in lung metastatic foci. Additionally, circulating tumor cells retained in lung capillaries were also reduced. These results suggest that the antimetastatic effect of SY is due to its inhibition of invadopodia formation, which occurs mainly through Src-dependent cytoskeleton rearrangement. We suggest that SY should be considered as a potential novel therapeutic agent for the treatment of breast cancer.

Pharmacologic regulation of AMPK in breast cancer affects cytoskeletal properties involved with microtentacle formation and re-attachment

The presence of tumor cells in the circulation is associated with a higher risk of metastasis in patients with breast cancer. Circulating breast tumor cells use tubulin-based structures known as microtentacles (McTNs) to re-attach to endothelial cells and arrest in distant organs. McTN formation is dependent on the opposing cytoskeletal forces of stable microtubules and the actin network. AMP-activated protein kinase (AMPK) is a cellular metabolic regulator that can alter actin and microtubule organization in epithelial cells. We report that AMPK can regulate the cytoskeleton of breast cancer cells in both attached and suspended conditions. We tested the effects of AMPK on microtubule stability and the actin-severing protein, cofilin. AMPK inhibition with compound c increased both microtubule stability and cofilin activation, which also resulted in higher McTN formation and re-attachment. Conversely, AMPK activation with A-769662 decreased microtubule stability and cofilin activation with concurrent decreases in McTN formation and cell re-attachment. This data shows for the first time that AMPK shifts the balance of cytoskeletal forces in suspended breast cancer cells, which affect their ability to form McTNs and re-attach. These results support a model where AMPK activators may be used therapeutically to reduce the metastatic efficiency of breast tumor cells.

IL-1β induces IL-6 production and increases invasiveness and estrogen-independent growth in a TG2-dependent manner in human breast cancer cells

Background

We previously reported that IL-6 and transglutaminase 2 (TG2) were expressed in more aggressive basal-like breast cancer cells, and TG2 and IL-6 expression gave these cells stem-cell-like phenotypes, increased invasive ability, and increased metastatic potential. In the present study, the underlying mechanism by which IL-6 production is induced in luminal-type breast cancer cells was evaluated, and TG2 overexpression, IL-1β stimulation, and IL-6 expression were found to give cancerous cells a hormone-independent phenotype.

Methods

Luminal-type breast cancer cells (MCF7 cells) were stably transfected with TG2. To evaluate the requirement for IL-6 neogenesis, MCF7 cells were stimulated with various cytokines. To evaluate tumorigenesis, cancer cells were grown in a three-dimensional culture system and grafted into the mammary fat pads of NOD/scid/IL-2Rγ^−/− mice.

Results

IL-1β induced IL-6 production in TG2-expressing MCF7 cells through an NF-kB-, PI3K-, and JNK-dependent mechanism. IL-1β increased stem-cell-like phenotypes, invasiveness, survival in a three-dimensional culture model, and estrogen-independent tumor growth of TG2-expressing MCF7 cells, which was attenuated by either anti-IL-6 or anti-IL-1β antibody treatment.

Conclusion

Within the inflammatory tumor microenvironment, IL-1β increases luminal-type breast cancer cell aggressiveness by stimulating IL-6 production through a TG2-dependent mechanism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2746-7) contains supplementary material, which is available to authorized users.

Liposomes Coated with Isolated Macrophage Membrane Can Target Lung Metastasis of Breast Cancer

Cancer metastasis leads to high mortality of breast cancer and is difficult to treat because of the poor delivery efficiency of drugs. Herein, we report the wrapping of a drug-carrying liposome with an isolated macrophage membrane to improve delivery to metastatic sites. The macrophage membrane decoration increased cellular uptake of the emtansine liposome in metastatic 4T1 breast cancer cells and had inhibitory effects on cell viability. In vivo, the macrophage membrane enabled the liposome to target metastatic cells and produced a notable inhibitory effect on lung metastasis of breast cancer. Our results provide a biomimetic strategy via the biological properties of macrophages to enhance the medical performance of a nanoparticle in vivo for treating cancer metastasis.

Cysteine cathepsin activity suppresses osteoclastogenesis of myeloid-derived suppressor cells in breast cancer

Cysteine cathepsin proteases contribute to many normal cellular functions, and their aberrant activity within various cell types can contribute to many diseases, including breast cancer. It is now well accepted that cathepsin proteases have numerous cell-specific functions within the tumor microenvironment that function to promote tumor growth and invasion, such that they may be valid targets for anti-metastatic therapeutic approaches. Using activity-based probes, we have examined the activity and expression of cysteine cathepsins in a mouse model of breast cancer metastasis to bone. In mice bearing highly metastatic tumors, we detected abundant cysteine cathepsin expression and activity in myeloid-derived suppressor cells (MDSCs). These immature immune cells have known metastasis-promoting roles, including immunosuppression and osteoclastogenesis, and we assessed the contribution of cysteine cathepsins to these functions. Blocking cysteine cathepsin activity with multiple small-molecule inhibitors resulted in enhanced differentiation of multinucleated osteoclasts. This highlights a potential role for cysteine cathepsin activity in suppressing the fusion of osteoclast precursor cells. In support of this hypothesis, we found that expression and activity of key cysteine cathepsins were downregulated during MDSC-osteoclast differentiation. Another cysteine protease, legumain, also inhibits osteoclastogenesis, in part through modulation of cathepsin L activity. Together, these data suggest that cysteine protease inhibition is associated with enhanced osteoclastogenesis, a process that has been implicated in bone metastasis.

Discovery of a Series of Acridinones as Mechanism-Based Tubulin Assembly Inhibitors with Anticancer Activity

Microtubules play critical roles in vital cell processes, including cell growth, division, and migration. Microtubule-targeting small molecules are chemotherapeutic agents that are widely used in the treatment of cancer. Many of these compounds are structurally complex natural products (e.g., paclitaxel, vinblastine, and vincristine) with multiple stereogenic centers. Because of the scarcity of their natural sources and the difficulty of their partial or total synthesis, as well as problems related to their bioavailability, toxicity, and resistance, there is an urgent need for novel microtubule binding agents that are effective for treating cancer but do not have these disadvantages. In the present work, our lead discovery effort toward less structurally complex synthetic compounds led to the discovery of a series of acridinones inspired by the structure of podophyllotoxin, a natural product with important microtubule assembly inhibitory activity, as novel mechanism-based tubulin assembly inhibitors with potent anticancer properties and low toxicity. The compounds were evaluated in vitro by wound healing assays employing the metastatic and triple negative breast cancer cell line MDA-MB-231. Four compounds with IC₅₀ values between 0.294 and 1.7 μM were identified. These compounds showed selective cytotoxicity against MDA-MB-231 and DU-145 cancer cell lines and promoted cell cycle arrest in G₂/M phase and apoptosis. Consistent with molecular modeling results, the acridinones inhibited tubulin assembly in in vitro polymerization assays with IC₅₀ values between 0.9 and 13 μM. Their binding to the colchicine-binding site of tubulin was confirmed through competitive assays.

Silibinin and indocyanine green-loaded nanoparticles inhibit the growth and metastasis of mammalian breast cancer cells in vitro

AIM

To improve the therapeutic efficacy of cancer treatments, combinational therapies based on nanosized drug delivery system (NDDS) has been developed recently. In this study we designed a new NDDS loaded with an anti-metastatic drug silibinin and a photothermal agent indocyanine green (ICG), and investigated its effects on the growth and metastasis of breast cancer cells in vitro.

METHODS

Silibinin and ICG were self-assembled into PCL lipid nanoparticles (SIPNs). Their physical characteristics including the particle size, zeta potential, morphology and in vitro drug release were examined. 4T1 mammalian breast cancer cells were used to evaluate their cellular internalization, cytotoxicity, and their influences on wound healing, in vitro cell migration and invasion.

RESULTS

SIPNs showed a well-defined spherical shape with averaged size of 126.3±0.4 nm and zeta potential of -10.3±0.2 mV. NIR laser irradiation substantially increased the in vitro release of silibinin from the SIPNs (58.3% at the first 8 h, and 97.8% for the total release). Furthermore, NIR laser irradiation markedly increased the uptake of SIPNs into 4T1 cells. Under the NIR laser irradiation, both SIPNs and IPNs (PCL lipid nanoparticles loaded with ICG alone) caused dose-dependent ablation of 4T1 cells. The wound healing, migration and invasion experiments showed that SIPNs exposed to NIR laser irradiation exhibited dramatic in vitro anti-metastasis effects.

CONCLUSION

SIPNs show temperature-sensitive drug release following NIR laser irradiation, which can inhibit the growth and metastasis of breast cancer cells in vitro.

Novel Strategies for Breast Cancer Imaging: New Imaging Agents to Guide Treatment

The development of molecular therapies for cancer treatment has created a need to image biochemical and molecular processes to appropriately select tumors that express the drug target, thereby predicting a positive response to therapy. Biomarker-driven molecular imaging is complementary to pathologic analysis and offers a more direct measure of drug efficacy and treatment response, potentially providing early insight into therapeutic futility and allowing response-adapted treatment strategies. Imaging also allows a unique means of assessing the heterogeneity of both intra- and intertumoral targets as well as a mixed response to therapy; this information is important in the setting of metastatic disease. Here we review the development of novel molecular imaging probes and combinations of probes to guide therapy for two new targets and associated therapeutic agents: cyclin-dependent kinase inhibitors and poly(adenosine diphosphate-ribose) polymerase inhibitors.

Novel Small-Molecule CX3CR1 Antagonist Impairs Metastatic Seeding and Colonization of Breast Cancer Cells

Recent evidence indicates that cancer cells, even in the absence of a primary tumor, recirculate from established secondary lesions to further seed and colonize skeleton and soft tissues, thus expanding metastatic dissemination and precipitating the clinical progression to terminal disease. Recently, we reported that breast cancer cells utilize the chemokine receptor CX3CR1 to exit the blood circulation and lodge to the skeleton of experimental animals. Now, we show that CX3CR1 is overexpressed in human breast tumors and skeletal metastases. To assess the clinical potential of targeting CX3CR1 in breast cancer, a functional role of CX3CR1 in metastatic seeding and progression was first validated using a neutralizing antibody for this receptor and transcriptional suppression by CRISPR interference (CRISPRi). Successively, we synthesized and characterized JMS-17-2, a potent and selective small-molecule antagonist of CX3CR1, which was used in preclinical animal models of seeding and established metastasis. Importantly, counteracting CX3CR1 activation impairs the lodging of circulating tumor cells to the skeleton and soft-tissue organs and also negatively affects further growth of established metastases. Furthermore, nine genes were identified that were similarly altered by JMS-17-2 and CRISPRi and could sustain CX3CR1 prometastatic activity. In conclusion, these data support the drug development of CX3CR1 antagonists, and promoting their clinical use will provide novel and effective tools to prevent or contain the progression of metastatic disease in breast cancer patients.

IMPLICATIONS

This work conclusively validates the instrumental role of CX3CR1 in the seeding of circulating cancer cells and is expected to pave the way for pairing novel inhibitors of this receptor with current standards of care for the treatment of breast cancer patients. Mol Cancer Res; 14(6); 518-27. ©2016 AACR.

The E3-ligase E6AP Represses Breast Cancer Metastasis via Regulation of ECT2-Rho Signaling

Metastatic disease is the major cause of breast cancer-related death and despite many advances, current therapies are rarely curative. Tumor cell migration and invasion require actin cytoskeletal reorganization to endow cells with capacity to disseminate and initiate the formation of secondary tumors. However, it is still unclear how these migratory cells colonize distant tissues to form macrometastases. The E6-associated protein, E6AP, acts both as an E3 ubiquitin-protein ligase and as a coactivator of steroid hormone receptors. We report that E6AP suppresses breast cancer invasiveness, colonization, and metastasis in mice, and in breast cancer patients, loss of E6AP associates with poor prognosis, particularly for basal breast cancer. E6AP regulates actin cytoskeletal remodeling via regulation of Rho GTPases, acting as a negative regulator of ECT2, a GEF required for activation of Rho GTPases. E6AP promotes ubiquitination and proteasomal degradation of ECT2 for which high expression predicts poor prognosis in breast cancer patients. We conclude that E6AP suppresses breast cancer metastasis by regulating actin cytoskeleton remodeling through the control of ECT2 and Rho GTPase activity. These findings establish E6AP as a novel suppressor of metastasis and provide a compelling rationale for inhibition of ECT2 as a therapeutic approach for patients with metastatic breast cancer. Cancer Res; 76(14); 4236-48. ©2016 AACR.

Curcumol Suppresses Breast Cancer Cell Metastasis by Inhibiting MMP-9 Via JNK1/2 and Akt-Dependent NF-κB Signaling Pathways

Curcumolhas been reported to possess antitumor activity. However, its effect and mechanisms against tumor metastasis are still unclear. This study is to investigate the inhibitory effect of curcumol on breast cancer cell metastasis and elucidate the underlying molecular mechanisms. Our results showed that noncytotoxicity was caused by curcumol within 10 to 40 µg/mL in MDA-MB-231 and 4T1 cells for 24 hours, whereas sustained treatment with curcumol for 14 days significantly suppressed the clonogenic activity of cells. Importantly, curcumol at noncytotoxic concentrations suppressed the migration ability of both MDA-MB-231 and 4T1 cells. Moreover, curcumol suppressed the migration and invasion of MDA-MB-231 cells in the Boyden chamber migration and invasion assay and inhibited the adhesion of MDA-MB-231 cells onto the matrigel. Further investigations revealed that curcumol decreased the enzyme activity and protein expression of matrix metalloproteinase (MMP-9) in MDA-MB-231 cells. Moreover, curcumol inhibited the activation of c-Jun N-terminal kinase (JNK) 1/2 and Akt (Ser473). Meanwhile, it also inhibited the nuclear translocation and transcriptional activity of nuclear factor κB (NF-κB). Furthermore, JNK inhibitor SP600125 and Akt (Ser473) inhibitor LY294002 enhanced the inhibition of curcumol on NF-κB p65 nuclear translocation. Finally, supplementation with SP600125, LY294002, or NF-κB inhibitor Ammonium pyrrolidinedithiocarbamate (PDTC) significantly enhanced the inhibitory effect of curcumol on MMP-9 expression and cell migration, invasion, and adhesion in MDA-MB-231 cells. Our findings provide evidence for the suppression of breast cancer cell metastasis by curcumol and suggest that the inhibition of MMP-9 via JNK1/2 and Akt (Ser473)-dependent NF-κB signaling pathways may be the underlying mechanisms.

Pragmatic medicine in solid cancer: a translational alternative to precision medicine

The precision medicine (PM) initiative is a response to the dismal outlook in solid cancer. Despite heterogeneity, common mechanistic denominators may exist across the spectrum of solid cancer. A shift from conventional research and development (R&D) toward PM will require conceptual and structural change. As individuals and as a society, we welcome innovation, but question change. We ask: In solid cancer, does PM identify and address the causes of prior failures, and, if so, are the proposed solutions feasible? And, when may we expect safer, more effective and affordable drugs in the clinic? Considerations that prompt a pragmatic rethink include a failure analysis of translational R&D in solid cancer suggesting that trials and regulations need to be aligned with the natural history of the disease. In successful therapeutic interventions in chronic, complex disease, surrogate markers and endpoints should be consistent with the Prentice's criteria. In solid cancer, drug induced tumor shrinkage, is a drug effect and not a disease response; tumor shrinkage does not reflect nor predict interruption of the disease. Overall, we support a pragmatic, multidisciplinary, and collaborative R&D, and suggest that direction be set by clinical need and utility, and by questions, not answers. PM will prove worthwhile if it could improve clinical outcomes. The lag in therapeutics relative to diagnostics is a cause for confusion. Overdiagnosis adds to fear and harm, especially in the absence of effective interventions. A revised initiative that prioritizes metastasis research could replicate the successful HIV/AIDS model in solid cancer. A pragmatic approach may further translational efforts toward meaningfully effective, generally available, and affordable solutions.

Current Approaches of Photothermal Therapy in Treating Cancer Metastasis with Nanotherapeutics

Cancer metastasis accounts for the high mortality of many types of cancer. Owing to the unique advantages of high specificity and minimal invasiveness, photothermal therapy (PTT) has been evidenced with great potential in treating cancer metastasis. In this review, we outline the current approaches of PTT with respect to its application in treating metastatic cancer. PTT can be used alone, guided with multimodal imaging, or combined with the current available therapies for effective treatment of cancer metastasis. Numerous types of photothermal nanotherapeutics (PTN) have been developed with encouraging therapeutic efficacy on metastatic cancer in many preclinical animal experiments. We summarize the design and performance of various PTN in PTT alone and their combinational therapy. We also point out the lacking area and the most promising approaches in this challenging field. In conclusion, PTT or their combinational therapy can provide an essential promising therapeutic modality against cancer metastasis.

Intraoperative Identification of Liver Cancer Microfoci Using a Targeted Near-Infrared Fluorescent Probe for Imaging-Guided Surgery

Difficulties in the highly sensitive detection of tumour microfoci represent a critical obstacle toward improved surgical intervention in liver cancer. Conventional preoperative imaging methods and surgeons’ subjective experience are limited by their inability to effectively detect tumour lesions measuring less than 2 mm; however, intraoperative fluorescence molecular imaging may overcome this limitation. Here, we synthesised an arginine-glycine-aspartic acid (RGD)-conjugated mesoporous silica nanoparticle (MSN) highly loaded with indocyanine green (ICG) dye that could accurately delineate liver cancer margins and provide excellent tumour-to-normal tissue contrast intraoperatively. The increased ICG loading capacity and tumour specificity enabled the identification of residual microtumours and satellite lesions measuring less than 1 mm in living mice. Histological analysis validated the sensitivity and accuracy of this approach. We believe this technique utilising a new fluorescent nanoprobe with intraoperative optical imaging may offer a more sensitive and accurate method for liver cancer resection guidance, resulting in better surgical outcomes.

pH-Responsive Wormlike Micelles with Sequential Metastasis Targeting Inhibit Lung Metastasis of Breast Cancer

Cancer metastasis is the main cause for the high mortality in breast cancer patients. Herein, we first report succinobucol-loaded pH-responsive wormlike micelles (PWMs) with sequential targeting capability to inhibit lung metastasis of breast cancer. PWMs can in a first step be delivered specifically to the sites of metastases in the lungs and then enable the intracellular pH-stimulus responsive drug release in cancer cells to improve the anti-metastatic effect. PWMs are identified as nanofibrillar assemblies with a diameter of 19.9 ± 1.9 nm and a length within the 50-200 nm range, and exhibited pH-sensitive drug release behavior in response to acidic intracellular environments. Moreover, PWMs can obviously inhibit the migration and invasion abilities of metastatic 4T1 breast cancer cells, and reduce the expression of the metastasis-associated vascular cell adhesion molecule-1 (VCAM-1) at 400 ng mL(-1) of succinobucol. In particular, PWMs can induce a higher specific accumulation in lung and be specifically delivered to the sites of metastases in lung, thereby leading to an 86.6% inhibition on lung metastasis of breast cancer. Therefore, the use of sequentially targeting PWMs can become an encouraging strategy for specific targeting and effective treatment of cancer metastasis.

A pH-Responsive Host-guest Nanosystem Loading Succinobucol Suppresses Lung Metastasis of Breast Cancer

Cancer metastasis is the leading reason for the high mortality of breast cancer. Herein, we report on a pH-responsive host-guest nanosystem of succinobucol (PHN) with pH-stimuli controlled drug release behavior to improve the therapeutic efficacy on lung metastasis of breast cancer. PHN was composed of the host polymer of β-cyclodextrin linked with multiple arms of N,N-diisopropylethylenediamine (βCD-DPA), the guest polymer of adamantyl end-capped methoxy poly(ethylene glycol) (mPEG-Ad), and the active agent of succinobucol. PHN comprises nanometer-sized homogenous spherical particles, and exhibits specific and rapid drug release in response to the intracellular acidic pH-stimuli. Then, the anti-metastatic efficacy of PHN is measured in metastatic 4T1 breast cancer cells, which effectively confirms the superior inhibitory effects on cell migration and invasion activities, VCAM-1 expression and cell-cell binding of RAW 264.7 to 4T1 cells. Moreover, PHN can be specifically delivered to the sites of metastatic nodules in lungs, and result in an obviously improved therapeutic efficacy on lung metastasis of breast cancer. Thereby, the pH-responsive host-guest nanosystem can be a promising drug delivery platform for effective treatment of cancer metastasis.

Emerging nanomedicine approaches fighting tumor metastasis: animal models, metastasis-targeted drug delivery, phototherapy, and immunotherapy

Nanomedicine approaches may bring new opportunities for tumor metastasis treatment.

Triple-Layered pH-Responsive Micelleplexes Loaded with siRNA and Cisplatin Prodrug for NF-Kappa B Targeted Treatment of Metastatic Breast Cancer

The combination of chemotherapy and RNA interference is a promising approach for efficient cancer therapy. However, the success of such a strategy is hampered by the lack of suitable vectors to coordinate small interfering RNA (siRNA) and chemotherapeutic drug into one single platform. We herein report a novel triple-layered pH-responsive micelleplex loading siRNA and alkylated cisplatin prodrug for NF-Kappa B targeted treatment of metastatic breast cancer. The micelles were self-assembled from poly(ethylene glycol)-block-poly(aminolated glycidyl methacrylate)-block-poly(2-(diisopropyl amino) ethyl methacrylate) (PEG-b-PAGA-b-PDPA) triblock copolymers. At pH 7.4, the cisplatin prodrug was encapsulated in the hydrophobic PDPA core and siRNA was loaded on the positively charged PAGA interlayer to form the micelleplexes. The PEG corona can prevent protein absorption during blood circulation, minimize non-specific interaction with the reticuloendothelial system, and prolong the systemic circulation of the micelleplexes. The positively charged PAGA interlayer can facilitate deep tumor penetration of the micelleplexes, which, upon cellular uptake, are dissociated in the early endosomes to release anticancer drug payload due to protonation of the PDPA core. Using a 4T1 breast cancer model, we demonstrate that this novel micelleplex co-loaded with cisplatin prodrug and siRNA-p65 is able to simultaneously inhibit tumor growth and suppress distant metastasis of the cancer cells by downregulating NF-kappa B expression. The results reported in this study suggest that siRNA and anticancer drug co-delivery using pH-responsive micelleplexes is a promising strategy for efficient treatment of metastatic cancer.

Physical nanoscale conduit-mediated communication between tumour cells and the endothelium modulates endothelial phenotype

Metastasis is a major cause of mortality and remains a hurdle in the search for a cure for cancer. Not much is known about metastatic cancer cells and endothelial cross-talk, which occurs at multiple stages during metastasis. Here we report a dynamic regulation of the endothelium by cancer cells through the formation of nanoscale intercellular membrane bridges, which act as physical conduits for transfer of microRNAs. The communication between the tumour cell and the endothelium upregulates markers associated with pathological endothelium, which is reversed by pharmacological inhibition of these nanoscale conduits. These results lead us to define the notion of ‘metastatic hijack': cancer cell-induced transformation of healthy endothelium into pathological endothelium via horizontal communication through the nanoscale conduits. Pharmacological perturbation of these nanoscale membrane bridges decreases metastatic foci in vivo. Targeting these nanoscale membrane bridges may potentially emerge as a new therapeutic opportunity in the management of metastatic cancer.

Cancer cells and stromal cells have been shown to pass cellular information between each other via exosomes. Here, the authors demonstrate that cancer cells can communicate with endothelial cells through nanoscale membrane bridges, and demonstrate that microRNAs are passed through these nanobridges, which modulates endothelial cell phenotype.

Targeting tumor metastases: Drug delivery mechanisms and technologies

Primary sites of tumor are the focal triggers of cancers, yet it is the subsequent metastasis events that cause the majority of the morbidity and mortality. Metastatic tumor cells exhibit a phenotype that differs from that of the parent cells, as they represent a resistant, invasive subpopulation of the original tumor, may have acquired additional genetic or epigenetic alterations under exposure to prior chemotherapeutic or radiotherapeutic treatments, and reside in a microenvironment differing from that of its origin. This combination of resistant phenotype and distal location make tracking and treating metastases particularly challenging. In this review, we highlight some of the unique biological traits of metastasis, which in turn, inspire emerging strategies for targeted imaging of metastasized tumors and metastasis-directed delivery of therapeutics.

Radium-223 dichloride therapy in breast cancer with osseous metastases

Osseous metastases occur frequently in patients with breast cancer. Few options exist for bone targeted therapy for hormone refractory patients with breast cancer with progressive bone metastases. We present a case of breast cancer with osseous metastases but no visceral metastases. The patient had been treated with surgery, chemotherapy, radiation and hormonal therapy, but still had extensive symptomatic osseous metastases. She received radium-223 dichloride, a therapeutic radiopharmaceutical Food and Drug Administration (FDA) approved for castration resistant prostate cancer with bone metastases. She tolerated the therapy well with no significant adverse effects. She had an excellent response with significant pain relief obviating need for regular analgaesics. Her tumour markers also dropped significantly. Osseous metastases assessed with F-18 fluorodeoxy glucose (FDG) positron emission tomography/CT (PET/CT) and F-18 sodium fluoride (NaF) bone PET/CT) scans at baseline, after two and six cycles, also showed interval improvement in the lesions. Radium-223 dichloride could potentially be a safe and useful therapeutic option in this setting.

Analysis of denosumab on skeletal-related events in patients with advanced breast cancer

BACKGROUND

Bisphosphonates, which are also known as osteoclast modifiers, are the standard of care in the treatment of skeletal-related events (SREs) in patients with breast cancer with metastatic bone disease. SREs are frequently a complication of advanced breast cancer, and they greatly increase morbidity and mortality in these patients. Unfortunately, even while undergoing bisphosphonate therapy, many patients experience SREs. In 2010, a fully human monoclonal antibody, denosumab (Xgeva®), was approved by the U.S. Food and Drug Administration as another option to treat SREs.

OBJECTIVES

This article analyzes four primary human research studies looking at the effectiveness and safety of denosumab as compared to bisphosphonates in the prevention of SREs in this vulnerable population.

METHODS

Articles published from 2006-2012 were located and reviewed through online database searches (CINAHL®, MEDLINE®, PubMed Plus) using the key words denosumab, skeletal-related event, breast cancer, metastases, and bisphosphonates.

FINDINGS

Studies reviewed showed comparative adverse events and safety profile between denosumab and bisphosphonates. However, denosumab was shown to have increased effectiveness in the prevention of SREs. This knowledge can influence the preventive measures taken by physicians and advanced practice nurses to improve the prevention of SREs in patients with metastatic breast cancer. It can also increase staff nurse knowledge and implementation of evidence-based practice.

Enhanced MAF Oncogene Expression and Breast Cancer Bone Metastasis

BACKGROUND

There are currently no biomarkers for early breast cancer patient populations at risk of bone metastasis. Identification of mediators of bone metastasis could be of clinical interest.

METHODS

A de novo unbiased screening approach based on selection of highly bone metastatic breast cancer cells in vivo was used to determine copy number aberrations (CNAs) associated with bone metastasis. The CNAs associated with bone metastasis were examined in independent primary breast cancer datasets with annotated clinical follow-up. The MAF gene encoded within the CNA associated with bone metastasis was subjected to gain and loss of function validation in breast cancer cells (MCF7, T47D, ZR-75, and 4T1), its downstream mechanism validated, and tested in clinical samples. A multivariable Cox cause-specific hazard model with competing events (death) was used to test the association between 16q23 or MAF and bone metastasis. All statistical tests were two-sided.

RESULTS

16q23 gain CNA encoding the transcription factor MAF mediates breast cancer bone metastasis through the control of PTHrP. 16q23 gain (hazard ratio (HR) for bone metastasis = 14.5, 95% confidence interval (CI) = 6.4 to 32.9, P < .001) as well as MAF overexpression (HR for bone metastasis = 2.5, 95% CI = 1.7 to 3.8, P < .001) in primary breast tumors were specifically associated with risk of metastasis to bone but not to other organs.

CONCLUSIONS

These results suggest that MAF is a mediator of breast cancer bone metastasis. 16q23 gain or MAF protein overexpression in tumors may help to select patients at risk of bone relapse.