Adjacent Cancer Cells Research Articles

Mitochondrial Bioenergetics at the Onset of Drug Resistance in Hematological Malignancies: An Overview.

The combined derangements in mitochondria network, function and dynamics can affect metabolism and ATP production, redox homeostasis and apoptosis triggering, contributing to cancer development in many different complex ways. In hematological malignancies, there is a strong relationship between cellular metabolism, mitochondrial bioenergetics, interconnections with supportive microenvironment and drug resistance. Lymphoma and chronic lymphocytic leukemia cells, e.g., adapt to intrinsic oxidative stress by increasing mitochondrial biogenesis. In other hematological disorders such as myeloma, on the contrary, bioenergetics changes, associated to increased mitochondrial fitness, derive from the adaptive response to drug-induced stress. In the bone marrow niche, a reverse Warburg effect has been recently described, consisting in metabolic changes occurring in stromal cells in the attempt to metabolically support adjacent cancer cells. Moreover, a physiological dynamic, based on mitochondria transfer, between tumor cells and their supporting stromal microenvironment has been described to sustain oxidative stress associated to proteostasis maintenance in multiple myeloma and leukemia. Increased mitochondrial biogenesis of tumor cells associated to acquisition of new mitochondria transferred by mesenchymal stromal cells results in augmented ATP production through increased oxidative phosphorylation (OX-PHOS), higher drug resistance, and resurgence after treatment. Accordingly, targeting mitochondrial biogenesis, electron transfer, mitochondrial DNA replication, or mitochondrial fatty acid transport increases therapy efficacy. In this review, we summarize selected examples of the mitochondrial derangements in hematological malignancies, which provide metabolic adaptation and apoptosis resistance, also supported by the crosstalk with tumor microenvironment. This field promises a rational design to improve target-therapy including the metabolic phenotype.

Quantification of Cellular Drug Biodistribution Addresses Challenges in Evaluating in vitro and in vivo Encapsulated Drug Delivery.

Nanoencapsulated drug delivery to solid tumors is a promising approach to overcome pharmacokinetic limitations of therapeutic drugs. However, encapsulation leads to complex drug biodistribution and delivery making analysis of delivery efficacy challenging. As proxies, nanocarrier accumulation or total tumor drug uptake in the tumor are used to evaluate delivery. Yet, these measurements fail to assess delivery of active, released drug to the target, and thus it commonly remains unknown if drug-target occupancy has been achieved. Here, we develop an approach to evaluate the delivery of encapsulated drug to the target, where residual drug target vacancy is measured using a fluorescent drug analog. In vitro measurements reveal that burst release governs drug delivery independent of nanoparticle uptake, and highlight limitations of evaluating nanoencapsulated drug delivery in these models. In vivo, however, our approach captures successful nanoencapsulated delivery, finding that tumor stromal cells drive nanoparticle accumulation and mediate drug delivery to adjacent cancer cells. These results, and generalizable approach, provide a critical advance to evaluate delivery of encapsulated drug to the drug target - the central objective of nanotherapeutics.

VEGF-C mediates tumor growth and metastasis through promoting EMT-epithelial breast cancer cell crosstalk.

It is well established that a subset of cells within primary breast cancers can undergo an epithelial to mesenchymal transition (EMT), although the role of EMT in metastasis remains controversial. We previously demonstrated that breast cancer cells that had undergone an oncogenic EMT could increase metastasis of neighboring cancer cells via non-canonical paracrine-mediated activation of GLI activity that is dependent on SIX1 expression in the EMT cancer cells. However, the mechanism by which these SIX1-expressing EMT cells activate GLI signaling remained unclear. In this study, we demonstrate a novel mechanism for activation of GLI-mediated signaling in epithelial breast tumor cells via EMT cell-induced production and secretion of VEGF-C. We show that VEGF-C, secreted by breast cancer cells that have undergone an EMT, promotes paracrine-mediated increases in proliferation, migration and invasion of epithelial breast cancer cells, via non-canonical activation of GLI-signaling. We further show that the aggressive phenotypes, including metastasis, imparted by EMT cells on adjacent epithelial cancer cells can be disrupted by either inhibiting VEGF-C in EMT cells or by knocking down NRP2, a receptor which interacts with VEGF-C, in neighboring epithelial cancer cells. Interrogation of TCGA and GEO public datasets supports the relevance of this pathway in human breast cancer, demonstrating that VEGF-C strongly correlates with activation of Hedgehog signaling and EMT in the human disease. Our study suggests that the VEGF-C/NRP2/GLI axis is a novel and conserved paracrine means by which EMT cells enhance metastasis, and provides potential targets for therapeutic intervention in this heterogeneous disease.

Epigenetic regulation of osteopontin splicing isoform c defines its role as a microenvironmental factor to promote the survival of colon cancer cells from 5-FU treatment

BackgroundDrug resistance to 5-fluorouracil (5-FU) and recurrence after chemotherapy in colorectal cancer remain a challenge to be resolved for the improvement of patient outcomes. It is recognized that a variety of secretory proteins released from the tumor cells exposed to chemo-drugs into the tumor microenvironment (TME) contributed to the cell-to-cell communication, and altered the drug sensitivity. One of these important factors is osteopontin (OPN), which exists in several functional forms from alternative splicing and post-translational processing. In colon cancer cells, increased total OPN expression was observed during the progression of tumors, however, the exact role and regulation of the OPN splicing isoforms was not well understood.MethodsWe assayed precisely the abundance of major OPN splicing isoforms under 5-FU treatments in colon cancer cell lines with different sensitivities to 5-FU, and also evaluated the effects of the condition medium from OPN splicing isoforms overexpressed cells on cell functions. The methods of nuclear calcium reporter assays and ChIP (chromatin immunoprecipitation) assays were used to investigate the molecular mechanism underlining the production of OPN isoforms.ResultsWe discovered that OPNc was a most increased splicing isoform to a significant abundance following 5-FU treatment of colon cancer cells. OPNc as a secretory protein in the conditioned medium exerted a more potent effect to promote cell survival in 5-FU than other OPN isoforms. The kinetic response of nuclear calcium signals could be used to indicate an immediate effect of the conditioned medium containing OPNc and other isoforms. Methyl-CpG binding protein 2 (MeCP2) was identified to regulate the splicing of opn gene, where the phosphorylation of MeCP2 at S421 site, possibly by calmodulin dependent protein kinase II (CaMKII) was required.ConclusionsThe results demonstrated that the production of OPNc was highly controlled under epigenetic regulations, where MeCP2 and the activation of nuclear calcium signaling were involved. It was also suggested that OPNc could transmit the stress signal of cells upon chemotherapy in TME and promoted the survival of adjacent colon cancer cells.

Developing Novel Means to Inhibit Metastasis Through Targeting Tumor Heterogeneity and EMT

It is well established that a subset of cells within primary breast cancers can undergo an epithelial to mesenchymal transition (EMT), although the role of EMT in metastasis remains controversial. We previously demonstrated a novel mechanism by which EMT contributes to metastasis, via mediating tumor cell crosstalk. In this seminar, I will discuss how breast cancer cells that have undergone an oncogenic EMT can increase metastasis of neighboring epithelial cancer cells via non‐canonical paracrine‐mediated activation of GLI activity that is dependent on Six1 expression in the EMT cancer cells. I will discuss how VEGF‐C, secreted by breast cancer cells that have undergone an EMT, promotes paracrine‐mediated increases in proliferation, migration, invasion, and metastasis of epithelial breast cancer cells, via non‐canonical activation of GLI‐signaling. Importantly, the aggressive phenotypes imparted by EMT cells on adjacent epithelial cancer cells can be disrupted by either inhibiting VEGF‐C in EMT cells or by knocking down NRP2, which interacts with VEGF‐C, in neighboring epithelial cancer cells both in vitro and in vivo. Interrogation of TCGA and GEO public datasets supports the relevance of this pathway in human breast cancer, as VEGF‐C and GLI pathway genes significantly positively correlate. Our study suggests that the VEGF‐C/NRP2/GLI axis may be a novel and conserved paracrine means by which EMT cells enhance metastasis, and provides potential targets for therapeutic intervention in this heterogeneous disease. In addition, because SIX1 activates VEGF‐C expression which leads to enhancement of metastasis via cell autonomous and non‐cell autonomous means, we have developed an inhibitor that targets SIX1 action and thereby inhibits metastatic disease. We describe results using this inhibitor in cell culture, where it inhibits SIX1 function and EMT, and in animals, where it inhibits metastasis without an effect on primary tumor growth.Support or Funding InformationColorado Cancer Translational Research Accelerator (CCTRA) PI Heide L. Ford, Co‐I Rui ZhaoNCI R01 CA224867 PIs Heide L. Ford and Michael T. Lewis

Specific overexpression of 15-lipoxygenase in endothelial cells promotes cancer cell death in an in vivo Lewis lung carcinoma mouse model

PurposeLipoxygenases (LOX) have been implicated in carcinogenesis, however both pro- and anti-carcinogenic effects have been reported in different cancer models. Using transgenic mice, which specifically overexpress human 15-lipoxygenase (ALOX15) in endothelial cells (EC), we previously demonstrated significant inhibition of tumor development. In the Lewis lung carcinoma (LLC) model, the primary tumor developed similarly in both wild type (WT) and ALOX15 overexpressing mice. However, metastases development was significantly inhibited in the transgenic mice. Here, we explored the molecular basis for the anti-metastatic effect of endothelial cell specific ALOX15 overexpression. Materials/methodsWe used ALOX15 overexpressing mice, and in-vitro cell model to evaluate the molecular effect of ALOX15 on EC and LLC cells. ResultsWhen LLC cells were injected in WT and ALOX15 overexpressing mice, we observed a higher degree of apoptosis and necrosis in primary and metastatic tumors of ALOX15 overexpressing animals. These anti-carcinogenic and anti-metastatic effects were paralleled by augmented expression of cyclin-dependent kinase inhibitor 1A (CDKN1A; p21) and of the peroxisome proliferators-activated receptor (PPAR)γ and by downregulation of the steady state concentrations of connexin26 mRNA. Consistent with these in vivo effects, ALOX15 overexpression in LLC and HeLa cancer cells in vitro significantly reduced cell viability in culture. In contrast, similar treatment of non-cancerous B2B epithelial cells did not impact cell viability. ConclusionsTaken together, our data suggests that endothelial cell specific overexpression of ALOX15 promotes apoptosis and necrosis in primary and metastatic tumors in mice, by upregulation of P21 and PPARγ expression in adjacent cancer cells.

Mechanism of anchorage-independency and tumor formation of cancer cells: possible involvement of cell membrane-bound laminin-332.

Cancer cells are characterized by anchorage-independency and tumor formation. Involvement of laminin-332 in the pathogenesis of cancer has also been reported. I present a theory that can explain these characteristics together. Proliferating keratinocytes in wound healing produce and deposit laminin-332, which is shown in the provisional basement membrane of a wound. In association with wound closure, expression of LG4/5 domain on the α3 chain of laminin-332 disappears, implicating cleavage of LG4/5 domain. LG4/5 domain expression indicates that laminin-332 prior to the cleavage is bound to the cell membrane, because LG4/5 domain is a cell binding site. In this binding, heparan sulfate proteoglycan on the cell surface seems to be the acceptor for LG4/5 domain. I named this laminin "cell membrane-bound laminin-332" (ML332). ML332 would then bind to integrin α3β1 via LG1-3 domain, the integrin binding site, and activate FAK and the following Ras/MAPK pathway. Therefore, ML332 eliminates the need for proliferating keratinocytes to bind to processed laminin-332 secreted and deposited into the basement membrane for their proliferation (anchorage-independency). This may hold true of every proliferating epithelial cell, either benign or malignant. Whereas wound closure deprives keratinocytes of anchorage-independency, such events do not occur in cancer cells, and cancer cells maintain anchorage-independency. In the basement membrane formation by epithelial cells, short arms of laminin-332 anchored to the cell membrane bind each other and generate a meshwork polymer. This is the three-arm interaction model. In a similar manner, short-arm interactions between adjacent cancer cells may occur and induce tumor formation.

Bone-Bound Bisphosphonates Inhibit Proliferation of Breast Cancer Cells.

Bisphosphonates are used in treating patients with breast cancer. In vitro studies have shown that bisphosphonates act directly on tumour cells, inhibiting cell proliferation and inducing apoptosis. In most such studies, drugs were added to culture media exposing cells to high bisphosphonate concentrations in solution. However, since bisphosphonates bind to bone hydroxyapatite with high affinity and remain bound for very long periods of time, these experimental systems are not an optimal model for the action of the drugs in vivo. The aim of this study was to determine whether bone-bound zoledronate has direct effects on adjacent breast cancer cells. Bone slices were pre-incubated with bisphosphonate solutions, washed, and seeded with cells of the breast cancer cell lines, MCF7 or MDA-MB-231. Proliferation was assessed by cell counts and thymidine incorporation for up to 72h. Inhibition of the mevalonate pathway was tested by measuring the levels of unprenylated Rap1A, and apoptosis was examined by the presence of cleaved caspase-8 on western blots. The proliferation rate of breast cancer cells on zoledronate-treated bone was significantly lower compared to cells on control bone. Other bisphosphonates showed a similar inhibitory effect, with an order of potency similar to their clinical potencies. Unprenylated Rap1A accumulated in MCF7 cells on zoledronate-treated bone, suggesting zoledronate acted through the inhibition of the mevalonate pathway. Accumulation of cleaved caspase-8 in MDA-MB-231 cells on bisphosphonate-treated bone indicated increased apoptosis in the cells. In conclusion, bone-bound zoledronate inhibits breast cancer cell proliferation, an activity that may contribute to its clinical anti-tumour effects.

Spindle assembly checkpoint MAD2 and CDC20 overexpressions and cell-in-cell formation in gastric cancer and its precursor lesions

Overexpression of mitotic arrest deficient 2 (MAD2) and/or cell division cycle 20 (CDC20) in the spindle assembly checkpoint leads to chromosomal instability and aneuploidy. Cell-in-cell (CIC) structures are formed by the process where cancer or immune cells are internalized into adjacent host cancer cells. Here, we investigated the clinicopathological significances of spindle assembly checkpoint protein overexpression and CIC structures in 829 cases of normal, premalignant, and gastric cancer (GC) lesions. MAD2 and CDC20 expressions were significantly increased in intestinal metaplasia, low-grade dysplasia, high-grade dysplasia (HGD), and early GC than normal mucosa, and their expression levels were the highest in HGD. Interestingly, CDC20 immunohistochemistry specifically stained the outer cells of CIC structures, which were the most frequently observed in early GC. In univariate analyses, MAD2 and CDC20 overexpressions and CIC formation were associated with older age, intestinal histology, lower tumor-node-metastasis stage, and longer recurrence-free survival and cancer-specific survival of GC patients. In multivariate survival analyses, MAD2 and CDC20 overexpressions were associated with better recurrence-free survival (hazard ratio, 0.61; P = .012) and cancer-specific survival (hazard ratio, 0.63; P = .043), respectively. In conclusion, MAD2 and CDC20 are the most expressed in HGD, suggesting their roles in the early stage of gastric carcinogenesis, whereas their overexpressions in GC are associated with intestinal histology and favorable clinicopathological parameters, which may be useful for immunohistochemical classification of chromosomal instability-type GC. Moreover, CDC20 is a novel immunohistochemical marker for highlighting CIC structures.

Abstract 5606: Eradication of triple-negative breast cancer cells by targeting glycosylated PD-L1

Abstract EGF signaling inhibits GSK3β-β-TrCP-mediated degradation of N-linked glycosylated programmed death ligand-1 (PD-L1), resulting in PD-L1 protein destabilization and enhanced immune checkpoint blockade efficacy. Here we show that EGF also mediates PD-L1 and receptor programmed cell death protein-1 (PD-1) interaction, requiring β-1,3-N-acetylglucosaminyl transferase (B3GNT3) expression in triple-negative breast cancer cells. Downregulation of B3GNT3 enhances cytotoxic T cell-mediated anti-tumor immunity. A monoclonal antibody targeting glycosylated PD-L1 (gPD-L1) blocks PD-L1/PD-1 interaction and promotes PD-L1 internalization and degradation. In addition to immune reactivation, drug-conjugated gPD-L1 antibody induces potent cell-killing effect as well as bystander-killing effect on adjacent cancer cells without PD-L1 expression with virtually no detectable toxicities. Our work suggests targeting protein glycosylation as a potential strategy to enhance immune checkpoint therapy. Citation Format: Seung-Oe Lim, Chia-Wei Li, Mien-Chie Hung. Eradication of triple-negative breast cancer cells by targeting glycosylated PD-L1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5606.

Cancer-cell-secreted exosomal miR-105 promotes tumour growth through the MYC-dependent metabolic reprogramming of stromal cells.

Cancer and other cells residing in the same niche engage various modes of interactions to synchronize and to buffer the negative effects of environmental changes. Extracellular miRNAs have been recently implicated in the intercellular crosstalk. Here we show a mechanistic model involving breast-cancer-secreted, extracellular-vesicle-encapsulated miR-105, which is induced by the oncoprotein MYC in cancer cells and in turn activates MYC signaling in cancer-associated fibroblasts (CAFs) to induce a metabolic program. This results in CAFs’ capacity to display different metabolic features in response to changes in the metabolic environment. When nutrients are sufficient, miR-105-reprogrammed CAFs enhance glucose and glutamine metabolism to fuel adjacent cancer cells. When nutrients are deprived whereas metabolic byproducts are accumulated, these CAFs detoxify metabolic wastes, including lactic acid and ammonium, by converting them into energy-rich metabolites. Thus, the miR-105-mediated metabolic reprogramming of stromal cells contributes to sustained tumour growth by conditioning the shared metabolic environment.

Teaming Up for Trouble: Cancer Cells, Transforming Growth Factor-β1 Signaling and the Epigenetic Corruption of Stromal Naïve Fibroblasts

It is well recognized that cancer cells subvert the phenotype of stromal naïve fibroblasts and instruct the neighboring cells to sustain their growth agenda. The mechanisms underpinning the switch of fibroblasts to cancer-associated fibroblasts (CAFs) are the focus of intense investigation. One of the most significant hallmarks of the biological identity of CAFs is that their tumor-promoting phenotype is stably maintained during in vitro and ex vivo propagation without the continual interaction with the adjacent cancer cells. In this review, we discuss robust evidence showing that the master cytokine Transforming Growth Factor-β1 (TGFβ-1) is a prime mover in reshaping, via epigenetic switches, the phenotype of stromal fibroblasts to a durable state. We also examine, in detail, the pervasive involvement of TGFβ-1 signaling from both cancer cells and CAFs in fostering cancer development, taking colorectal cancer (CRC) as a paradigm of human neoplasia. Finally, we review the stroma-centric anticancer therapeutic approach focused on CAFs—the most abundant cell population of the tumor microenvironment (TME)—as target cells.

Eradication of Triple-Negative Breast Cancer Cells by Targeting Glycosylated PD-L1

Protein glycosylation provides proteomic diversity in regulating protein localization, stability, and activity; it remains largely unknown whether the sugar moiety contributes to immunosuppression. In the study of immune receptor glycosylation, we showed that EGF induces programmed death ligand 1 (PD-L1) and receptor programmed cell death protein 1 (PD-1) interaction, requiring β-1,3-N-acetylglucosaminyl transferase (B3GNT3) expression in triple-negative breast cancer. Downregulation of B3GNT3 enhances cytotoxic Tcell-mediated anti-tumor immunity. A monoclonal antibody targeting glycosylated PD-L1 (gPD-L1) blocks PD-L1/PD-1 interaction and promotes PD-L1 internalization and degradation. In addition to immune reactivation, drug-conjugated gPD-L1 antibody induces a potent cell-killing effect as well as a bystander-killing effect on adjacent cancer cells lacking PD-L1 expression without any detectable toxicity. Our work suggests targeting protein glycosylation as a potential strategy to enhance immune checkpoint therapy.

Cytotoxic stress induces transfer of mitochondria-associated human endogenous retroviral RNA and proteins between cancer cells.

About 8 % of the human genome consists of human endogenous retroviruses (HERVs), which are relicts of ancient exogenous retroviral infections incurred during evolution. Although the majority of HERVs have functional gene defects or epigenetic modifications, many of them are still able to produce retroviral proteins that have been proposed to be involved in cellular transformation and cancer development.We found that, in chemo-resistant U87RETO glioblastoma cells, cytotoxic stress induced by etoposide promotes accumulation and large-scale fission of mitochondria, associated with the detection of HERV-WE1 (syncytin-1) and HERV-FRD1 (syncytin-2) in these organelles. In addition, mitochondrial preparations also contained the corresponding receptors, i.e. ASCT2 and MFSD2. We clearly demonstrated that mitochondria associated with HERV-proteins were shuttled between adjacent cancer cells not only via tunneling tubes, but also by direct cellular uptake across the cell membrane. Furthermore, anti-syncytin-1 and anti-syncytin-2 antibodies were able to specifically block this direct cellular uptake of mitochondria even more than antibodies targeting the cognate receptors.Here, we suggest that the association of mitochondria with syncytin-1/syncytin-2 together with their respective receptors could represent a novel mechanism of cell-to-cell transfer. In chemotherapy-refractory cancer cells, this might open up attractive avenues to novel mitochondria-targeting therapies.

TRAF4 promotes lung cancer aggressiveness by modulating tumor microenvironment in normal fibroblasts

Normal fibroblasts surrounding tumor cells play a crucial role in cancer progression through formation of the tumor microenvironment. Because factors secreted from normal fibroblasts can modulate the tumor microenvironment, it is necessary to identify key factors associated with regulation of secreted factors and to investigate the molecular mechanisms contributing to the tumor microenvironment formation process. In this study, we found that radiation induced the expression and K63-linkage poly-ubiquitination of TRAF4 in normal lung fibroblasts. The K63-linkage poly-ubiquitinated TRAF4 formed complexes with NOX2 or NOX4 by mediating phosphorylated p47-phox in normal lung fibroblasts. Moreover, we showed that TRAF4 stabilized NOX complexes by decreasing lysosomal degradation of NOX2 and NOX4 after irradiation. NOX complexes increased endosomal ROS levels that were permeable into cytoplasm, leading to NF-κB-mediated ICAM1 up-regulation. Soluble ICAM1 was subsequently secreted into conditioned media of radiation-activated normal lung fibroblasts. The conditioned media from irradiated normal fibroblasts enhanced proliferation and epithelial-mesenchymal transition of non-small cell lung cancer cells both in vitro and in vivo. These results demonstrate that TRAF4 in irradiated fibroblasts is positively associated with aggressiveness of adjacent cancer cells by altering the tumor microenvironment. Thus, we suggest that regulation of TRAF4 might be a promising strategy for cancer therapy.

Abstract 5894: Stromal fibroblasts from metastatic breast cancer promote proliferation and migration of breast cancer cell and regulate its stemness

Abstract Breast cancer is one of the most common causes of cancer-related death in women in the world. Although most research is focused on the tumor cells, it is important to elucidate the molecular nature of the tumor-stromal relationship to truly understand the biology of breast tumor growth. Cancer-associated fibroblasts (CAFs) are the major cellular constituents in the tumor microenvironment. CAFs are in direct contact with the adjacent cancer cells and crosstalk with them through soluble cytokines, growth factors and exosomes during carcinogenesis in human breast cancer. To determine for the first time the function of CAFs in metastatic sites of breast cancer, we collected CAFs from human patients of metastatic sites (m-CAFs) and compared them with CAFs from primary tumor (p-CAFs) and normal fibroblasts (NFs). We found that m-CAFs expressed higher levels of α-smooth muscle actin (SMA) compared with p-CAFs and NFs. The proliferation of MDA-MB-436 breast cancer cells was significantly increased by treatment with conditioned medium (CM) from m-CAFs compared with p-CAFs in vitro. Also, CM by m-CAFs induced paclitaxel resistance in MDA-MB-436 cells, suggesting that soluble factors produced by m-CAFs promote chemo-resistance, to a greater extent than CM from p-CAFs. The migration and invasion ability of MDA-MB-436 cells co-cultured with m-CAFs CM was significantly greater than that of the p-CAFs CM. m-CAFs outperformed the p-CAFs and NFs in terms of their ability to promote sphere-forming activity in a 3D in vitro culture model. Furthermore, m-CAFs protected MDA-MB-436 cells from the cytotoxic effects of doxorubicin more than p-CAFs in this spheroid 3-D culture. When MDA-MB-436 cells were sorted from these spheroids and grew in the respective CMs, they showed higher expression of the stemness markers of CD44+CD24- compared with cells obtained from p-CAFs/MDA-MB-436 spheroids. Also these cells from the co-culture with m-CAFs experienced with the cadherin switch. Nanog has been demonstrated to promote chemoresistant and epithelial-mesenchymal transition (EMT). The results displayed that MDA-MB-436 cells incubated with the CM from the m-CAFs had a higher expression of Nanog compared with that of p-CAFs. RNA-seq results showed that IGF2 is one of the most different genes between m-CAFs and p-CAFs, its expression was more significant in m-CAFs co-cultured with MDA-MB-436 cells than p-CAFs. The signaling pathway in MDA-MB-436 cells were comparable between co-cultured with m-CAFs CM and the IGF2 stimulation at 2 hours. All these data illustrates that fibroblasts isolated from metastatic site differed in terms of their ability to promote breast cancer cells progression compared to p-CAFs. Our data suggests that m-CAFs are more potent than p-CAFs in inducing the proliferation, migration, drug resistance and cancer stemness of breast cancer cells in an in vitro model. Citation Format: Yirui Gui, Adriana Aguilar-Mahecha, Marguerite Buchanan, Mark Basik. Stromal fibroblasts from metastatic breast cancer promote proliferation and migration of breast cancer cell and regulate its stemness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5894. doi:10.1158/1538-7445.AM2017-5894

The Power Behind the Throne: Senescence and the Hallmarks of Cancer

Cellular senescence is a state of stable proliferative arrest triggered by various stimuli, including oncogenic and other cellular stress. Senescent cells are highly metabolically active and have diverse and profound nonautonomous effects through the senescence-associated secretory phenotype (SASP). It has become increasingly evident that senescent cells can have tumour suppressive or pro-oncogenic effects on adjacent cancer cells and other players in the tumor microenvironment such as the stroma, vasculature, and immune system. Thus, the last decade or so has witnessed a huge leap forward in our understanding of the biology of senescence, promoting it from an autonomous tumor suppressor to a complex, dynamic, and interactive phenotype. It is perhaps not a coincidence that the concept of the “hallmarks of cancer” has also evolved during this period, with the latest iteration ( Hanahan & Weinberg 2011 ) focusing more on the microenvironment. Here, we suggest that cellular senescence could underpin the biology of many of the hallmarks of cancer, making it the true power behind the throne.

IPS-derived MSCs from an expandable bank to deliver a prodrug-converting enzyme that limits growth and metastases of human breast cancers

One attractive strategy to treat cancers is to deliver an exogenous enzyme that will convert a non-toxic compound to a highly toxic derivative. The strategy was tested with viral vectors but was disappointing because the efficiency of transduction into tumor cells was too low. Recent reports demonstrated that the limitation can be addressed by using tissue-derived mesenchymal stromal cells (MSCs) to deliver enzyme/prodrug systems that kill adjacent cancer cells through bystander effects. Here we addressed the limitation that tissue-derived MSCs vary in their properties and are difficult to generate in the large numbers needed for clinical applications. We prepared a Feeder Stock of MSCs from induced pluripotent stem cells (iPSs) that provided an extensively expandable source of standardized cells. We then transduced the iPS-derived MSCs to express cytosine deaminase and injected them locally into a mouse xenogeneic model of human breast cancer. After administration of the prodrug (5-fluorocytosine), the transduced iPS-MSCs both limited growth of preformed tumors and decreased lung metastases.

Visualization of exosome-mediated miR-210 transfer from hypoxic tumor cells.

Cancer cells actively release exosomes carrying specific cellular components, such as proteins, mRNA, and miRNA, to communicate with various cells in the tumor microenvironment. We visualized exosome-mediated transfer of miR-210 from hypoxic breast cancer cells to neighboring cells using a miR-210 specific reporter system. By in vitro and in vivo visualization, we found that exosomes with miR-210 were transferred to cells in the tumor microenvironment and that miR-210 was involved in expression of vascular remodeling related genes, such as Ephrin A3 and PTP1B, to promote angiogenesis. These results indicate that cellular components, such as miRNAs from hypoxic cancer cells, spread to adjacent cancer cells in the tumor microenvironment via exosomes and influence tumor progression.

Domino-Like Intercellular Delivery of Undecylenic Acid-Conjugated Porous Silicon Nanoparticles for Deep Tumor Penetration.

Improving the intratumoral distribution of anticancer agents remains the critical challenge for developing efficient cancer chemotherapy. Luminescent porous silicon nanoparticles (PSiNPs) have attracted considerable attention in the biomedical field especially in drug delivery. Here, we described the lysosomal exocytosis-mediated domino-like intercellular delivery of undecylenic acid-conjugated PSiNPs (UA-PSiNPs) for deep tumor penetration. UA-PSiNPs with significantly improved stability in physiological conditions were internalized into tumor cells by macropinocytosis-, caveolae-, and clathrin-mediated endocytosis and mainly colocalized with Golgi apparatus and lysosomes. Substantial evidence showed that UA-PSiNPs was excreted from cells via lysosomal exocytosis after cellular uptake. The exocytosed UA-PSiNPs induced a domino-like infection of adjacent cancer cells and allowed encapsulated doxorubicin (DOX) to deeply penetrate into both three-dimensional tumor spheroids and in vivo tumors. In addition, DOX-loaded UA-PSiNPs exhibited strong antitumor activity and few side effects in vivo. This study demonstrated that UA-PSiNPs as a drug carrier might be applied for deep tumor penetration, offering a new insight into the design of more efficient delivery systems of anticancer drugs.