Cancer Associated Fibroblasts

Alteration in the density and composition of extracellular matrix (ECM) occurs in tumors. The alterations toward both stiffness and degradation are contributed to tumor growth and progression. Cancer‐associated fibroblasts (CAFs) are the main contributors to ECM stiffness and degradation. The cells interact with almost all cells within the tumor microenvironment (TME) that could enable them to modulate ECM components for tumorigenic purposes. Cross‐talks between CAFs with cancer cells and macrophage type 2 (M2) cells are pivotal for ECM stiffness and degradation. CAFs induce hypoxia within the TME, which is one of the key inducers of both stiffness and degradation. Cancer cell modulatory roles in integrin receptors are key for adjusting ECM constituents to either fates. Cancer cell proliferation, migration, and invasion as well as angiogenesis are consequences of ECM stiffness and degradation. ECM stiffness in a transforming growth factor‐β (TGF‐β) related pathway could make a bridge in the basement membrane, and ECM degradation in a matrix metalloproteinase (MMP)‐related pathway could make a path in the TME, both of which contribute to cancer cell invasion. ECM stiffness is also obstructive for drug penetration to the tumor site. Therefore, it would be a promising strategy to make a homeostasis in ECM for easy penetration of chemotherapeutic drugs and increasing the efficacy of antitumor approaches. MMP and TGF‐β inhibitors, CAF and M2 reprogramming toward their normal counterparts, reduction of TME hypoxia and hampering integrin signaling are among the promising approaches for the modulation of ECM in favor of tumor regression.

Cell death is the last fate of the life cycle of cells. Different pathways involved in cell death are known to date, and are mostly represented by apoptosis, necrosis, and autophagy. Autophagy is one of the most preserved cell death pathways, characterized by the elimination of large parts of cytoplasmic components after being consumed by a double-membraned vesicle called an autophagosome. The formed autophagosome then fuses with a lysosome containing degrading enzymes and leads to the digestion of the autophagosome content. Autophagy is triggered by stress-related inducers, and is partially dependent on apoptotic proteins. It plays a major role in cancer, particularly in the tumor microenvironment where it has a paradoxical function in acting as a tumor suppressor and also as a tumor promoter. In the tumor microenvironment, autophagy regulates the differentiation of macrophages into tumor-associated macrophages (TAMs) and fibroblasts into cancer-associated fibroblasts (CAFs). TAMs and CAFs are abundantly present in the tumor microenvironment, and participate actively in tumor growth, tumor invasiveness, and tumor resistance to chemotherapy.

Cancer associated fibroblasts (CAFs) as the dominant, long-lived and highly plastic cells within the tumor microenvironment (TME) with multi-faceted roles that are endowed with tumor aggressive features. They can instruct and shape the stroma of tumor into being a highly qualified bed for cellular recruitment, differentiation and plasticity in the host tissue or secondary organ/s. In this Review, we have a discussion over CAF reprogramming as a general concept, inducers and outcomes, pursued by suggesting potential strategies to combat this key promoter of tumor.

Tumor microenvironment participates in all stages of tumor progression and has emerged as a promising therapeutic target for cancer therapy. Rapid progress in the field of molecular self-assembly using various biological molecules has resulted in the fabrication of nanoformulations, specifically targeting and regulating the microenvironment components to inhibit tumor malignancies. This inhibition process is based on the differentiating biophysicochemical cues guiding tumor and normal tissue microenvironments. Peptides and peptide derivatives, owing to their great biocompatibility, chemical versatility, bioactivity, environmental sensitivity and biological recognition abilities, have been widely utilized as building blocks to construct multifunctional nanostructures for targeted drug delivery and controlled release. Several groups of peptides have been identified with the ability to penetrate plasma membranes, to regulate the essential signaling pathways of angiogenesis and immune r...

Background: Cancer-Associated Fibroblasts (CAFs) are stromal ‘activated’ fibroblasts known to promote tumor growth, angiogenesis and invasion in certain carcinomas.  Microvascular proliferation (MVP) is a hallmark of angiogenesis in aggressive cancers.  We examined the presence of MVP in relation to clinical risk factors, and quantified CAF infiltration, across the spectrum of human neuroblastoma (NB) tumors, and in xenografts before and after enrichment for Schwann cells or anti-angiogenic treatment.  Methods: Human NB tumors were classified into six diagnostic categories according to the WHO and International Neuroblastoma Pathologic Classification criteria for Schwannian stroma (SS)-poor, -rich or -dominant tumors.  NB (SMS-KCNR) cells were inoculated either inside or outside the sciatic nerve of nude mice to generate xenografts with infiltrating Schwann cells.  Valproic acid was used as anti-angiogenic agent.  MVP was assessed on H&E stain.  CAFs were characterized by positive immunostaining for alpha-Smooth Muscle Actin (alpha-SMA) and were distinguished from pericytes by staining negatively for high-MW Caldesmon.  CAF infiltration was assessed by percent alpha-SMA positive areas either by semiquantitative microscopy or by automated cellular image analysis (ACIS II).  Associations between MVP, survival, risk groups, tumor stage, histology and CAFs were assessed by Kaplan-Meier curves, regression analysis, Chi-square and Student’s t-tests.  Results:  We demonstrated significant associations between MVP and SS-poor histology, decreased survival and high risk cases.  The level of CAFs was strongly associated with SS-poor histology and with MVP.  Anti-angiogenic treatment abrogated MVP.  In xenografts with infiltrating Schwann cells, the number of CAF/mm2 was ~7-fold less than in the controls.  Conclusion:  Our results suggest that CAFs play a role in promoting angiogenesis and aggressive behavior of Neuroblastoma tumors, and that Schwannian stroma may inhibit CAF infiltration or activation.  This may guide development of anti-stromal therapeutics, and may impact risk group classification and patient stratification for future clinical trials in Neuroblastoma.

Rho-associated coiled-coil kinase 2 (ROCK2) is an oncoprotein that controls cytoskeleton organization and acts as prognostic marker in different types of solid tumors. ROCK2 overexpression is also observed in cancer-associated fibroblasts (CAF), which suggests its relevance within the tumor microenvironment. This study aimed to access the prognostic value of ROCK2 in oral squamous cell carcinomas (OSCC) and its association with CAF density. ROCK2 immunohistochemical analysis was applied in 93 OSCC samples from 2 centers in Brazil and Finland. The samples were also stained for isoform α of smooth muscle actin (α-SMA) to characterize the presence of CAF in the tumor stroma. Clinicopathologic associations were analyzed using chi-square test, survival curves were constructed according to the Kaplan-Meier method, and Cox proportional hazard model was applied for multivariate survival analysis. Advanced clinical stage (p=0.002) and increased density of CAF (p=0.002) were significantly ass...

Epithelioid and fibroblastoid subsets coexist in the human sarcomatoid renal cell carcinoma (sRCC) cell line, RCC52, according to previous clonal studies. Herein, using monoclonal antibodies to CD44 and CD24 markers, we identified and isolated these two populations, and showed that CD44bright/CD24dim and CD44bright/CD24bright phenotypes correspond to epithelioid and fibroblastoid subsets, respectively. Both sorted subsets displayed different levels of tumorigenicity in xenotransplantation, indicating that each harbored its own cancer stem cells (CSCs). The CD44bright/CD24bright subset, associated with higher expression of MMP-7, -8 and TIMP-1 transcripts, showed greater migratory/invasive potential than the CD44bright/CD24dim subset, which was associated with higher expression of MMP-2, -9 and TIMP-2 transcripts. Both subsets differentially expressed stemness gene products c-Myc, Oct4A, Notch1, Notch2 and Notch3, and the RCC stem cell marker, CD105 in 4-5% of RCC52 cells. These resu...

Tumor-associated macrophages (TAMs) promote tumor development, invasion, and dissemination by various mechanisms. In this study, using an orthotopic colorectal cancer (CRC) model, we found that monocyte-derived TAMs advance tumor development by the remodeling of its extracellular matrix (ECM) composition and structure. Unbiased transcriptomic and proteomic analyses of (a) TAM-abundant and -deficient tumor tissues and (b) sorted tumor-associated and -resident colonic macrophage subpopulations defined a distinct TAM-induced ECM molecular signature composed of an ensemble of matricellular proteins and remodeling enzymes they provide to the tumor microenvironment. Remarkably, many of these ECM proteins are specifically increased in human CRC versus healthy colon. Specifically, we demonstrate that although differentiating into TAMs, monocytes up-regulate matrix-remodeling programs associated with the synthesis and assembly of collagenous ECM, specifically collagen types I, VI, and XIV. T...

Stromal Derived Factor-1α (SDF-1α) and its cognate receptor CXCR4 play a key role in mediating breast cancer cell invasion and metastasis. Therefore, drugs able to inhibit CXCR4 activation may add critical tools to reduce tumor progression, especially in the most aggressive form of the breast cancer disease. Peroxisome Proliferator-Activated Receptor (PPAR) γ, a member of the nuclear receptor superfamily, has been found to downregulate CXCR4 gene expression in different cancer cells, however the molecular mechanism underlying this effect is not fully understood. Here, we identified a novel PPARγ-mediated mechanism that negatively regulates CXCR4 expression in both epithelial and stromal breast cancer cells. We found that ligand-activated PPARγ downregulated CXCR4 transcriptional activity through the recruitment of the silencing mediator of retinoid and thyroid hormone receptor (SMRT) corepressor onto a newly identified PPAR response element (PPRE) within the CXCR4 promoter in breast...

The binding of hepatocyte growth factor (HGF) to its receptor MET activates a signaling cascade that promotes cell survival, proliferation, cell scattering, migration and invasion of malignant cells. HGF is secreted by cancer cells or by tumor-associated fibroblasts as pro-HGF, an inactive precursor. A key step in the regulation of HGF/MET signaling is proteolytic processing of pro-HGF to its active form by one of the three serine proteases, matriptase, hepsin or HGF activator (HGFA).We developed SRI 31215, a small molecule that acts as a triplex inhibitor of matriptase, hepsin and HGFA and mimics the activity of HAI-1/2, endogenous inhibitors of HGF activation. We demonstrated that SRI 31215 inhibits fibroblast-induced MET activation, epithelial-mesenchymal transition and migration of cancer cells. SRI 31215 overcomes primary resistance to cetuximab and gefitinib in HGF-producing colon cancer cells and prevents fibroblast-mediated resistance to EGFR inhibitors. Thus, SRI 31215 bloc...

The secretome of cancer and stromal cells generates a microenvironment that contributes to tumour cell invasion and angiogenesis. Here we compare the secretome of human mammary normal and cancer-associated fibroblasts (CAFs). We discover that the chloride intracellular channel protein 3 (CLIC3) is an abundant component of the CAF secretome. Secreted CLIC3 promotes invasive behaviour of endothelial cells to drive angiogenesis and increases invasiveness of cancer cells both in vivo and in 3D cell culture models, and this requires active transglutaminase-2 (TGM2). CLIC3 acts as a glutathione-dependent oxidoreductase that reduces TGM2 and regulates TGM2 binding to its cofactors. Finally, CLIC3 is also secreted by cancer cells, is abundant in the stromal and tumour compartments of aggressive ovarian cancers and its levels correlate with poor clinical outcome. This work reveals a previously undescribed invasive mechanism whereby the secretion of a glutathione-dependent oxidoreductase driv...

Phosphotyrosine (pTyr)-regulated protein complexes play critical roles in cancer signaling. The systematic characterization of these protein complexes in tumor samples remains a challenge due to their limited access and the transient nature of pTyr-mediated interactions. We developed a hybrid chemical proteomics approach, termed Photo-pTyr-scaffold, by engineering Src homology 2 (SH2) domains, which specifically bind pTyr proteins, with both trifunctional chemical probes and genetic mutations to overcome these challenges. Dynamic SH2 domain-scaffolding protein complexes were efficiently cross-linked under mild UV light, captured by biotin tag, and identified by mass spectrometry. This approach was successfully used to profile native pTyr protein complexes from breast cancer tissue samples on a proteome scale with high selectivity, achieving about 100 times higher sensitivity for detecting pTyr signaling proteins than that afforded by traditional immunohistochemical methods. Among mo...

Autophagy is a cellular homeostatic mechanism where proteins and organelles are digested and recycled to provide an alternative source of building blocks and energy to cells. The role of autophagy in cancer microenvironment is still poorly understood. Here, we present a microfluidic system allowing monitoring of the crosstalk between single cells. We used this system to study how tumor cells induced autophagy in the stromal niche. Firstly, we could confirm that transforming growth factor β1 (TGFβ1) secreted from breast tumor cells is a paracrine mediator of tumor-stroma interaction leading to the activation of autophagy in the stroma component fibroblasts. Through proof of concept experiments using TGFβ1 as a model factor, we could demonstrate real time monitoring of autophagy induction in fibroblasts by single tumor cells. Retrieval of individual tumor cells from the microfluidic system and their subsequent genomic analysis was possible, allowing us to determine the nature of the factor mediating tumor-stroma interactions. Therefore, our microfluidic platform might be used as a promising tool for quantitative investigation of tumor–stroma interactions, especially for and high-throughput screening of paracrine factors that are secreted from heterogeneous tumor cell populations. Interactions between cancer cells and the neighboring stroma play a critical role in tumorigenesis, and an in-depth understanding of intercellular communication is of great significance for the development of novel therapeutic strategies 1–3. Heterogeneity of tumor cells is evident, and its profound impact in clinical applications is highly recognized 4. However, conventional tools used to study cell-to-cell interactions only deliver averaged information from a population of cells and fail to provide information on the distribution of responses reflecting the heterogeneity of individual cells. Microfluidic devices have emerged as useful tools for single-cell analysis 5–7. Phenotype heterogeneity 8 , par-acrine secretion 9 , and DNA repair capacities with different genetic backgrounds 10 are among the cellular properties that have been analyzed using single-cell based systems. Cell-to-cell interactions may also be studied at a single-cell level. For example, using single-cell pairing techniques, effects of cell-to-cell interaction on migration and proliferation patterns 11 and contact-dependent organoid formation 12 have been analyzed. In addition, the heterogeneous dynamics of CD8 T-cells during their interaction with lymphocytes have been investigated 13. However, to the best of our knowledge, single-cell-based techniques have been rarely used for studying the interactions of tumor cells with tissues surrounding them, i.e., the stroma. Furthermore, the retrieval of individual

Aging is associated with a rising incidence of cutaneous squamous cell carcinoma (cSCC), an aggressive skin cancer with the potential for local invasion and metastasis. Acquisition of a senescence-associated secretory phenotype (SASP) in dermal fibroblasts has been postulated to promote skin cancer progression in elderly individuals. The underlying molecular mechanisms are largely unexplored. We show that Chemerin, a previously unreported SASP factor released from senescent human dermal fibroblasts, promotes cSCC cell migration, a key feature driving tumor progression. Whereas the Chemerin abundance is downregulated in malignant cSCC cells, increased Chemerin transcripts and protein concentrations are detected in replicative senescent fibroblasts in vitro and in the fibroblast of skin sections from old donors, indicating that a Chemerin gradient is built up in the dermis of elderly. Using Transwell® migration assays, we show that Chemerin enhances the chemotaxis of different cSCC ce...

Androgen receptor (AR) regulation pathways are essential for supporting the growth and survival of prostate cancer cells. Recently, sub-populations of prostate cancer cells have been identified with stem cell features and are associated with the emergence of treatment-resistant prostate cancer. Here, we explored the function of AR in prostate cancer-associated fibroblasts (CAFs) relative to growth and stem cell-associated characteristics. CAFs were isolated from the murine cPten(-/-)L prostate cancer model and cultured with human prostate cancer epithelial (hPCa) cells. A murine-specific AR antisense oligonucleotide (ASO) was used to suppress the expression of AR in the CAF cells. CAFs express low, but significant levels of AR relative to fibroblasts derived from non-malignant tissue. CAFs promoted growth and colony formation of hPCa cells, which was attenuated by the suppression of AR expression. Surprisingly, AR-depleted CAFs promoted increased stem cell marker expression in hPCa ...

Purpose: Cancer metastasis can occur at the early stage of tumor development when a primary tumor at the microscopic size. In particular, the interaction of malignant cells with other cell types including cancer-associated fibroblasts (CAFs) in promoting metastasis at the early stage of tumor development remains largely unknown. Here, we investigated the role of CAFs in facilitating the initial events of cancer metastasis when primary tumors were at microscopic sizes.  <p>Experimental design: Multi-color-coded cancer cells and CAFs were co-implanted into the transparent zebrafish body and metastasis at a single cell level was monitored in living animals. Healthy fibroblasts, tumor factor-educated fibroblasts, and CAFs isolated from various tumors were tested for their ability to facilitate metastasis.<br /><br />Results: We showed that CAFs promoted cancer cell metastasis at the very early stage during primary tumor development. When a primary tumor at the microsco...

Cancer-associated fibroblasts (CAFs) are the major components of the tumor microenvironment. They may drive tumor progression, although the mechanisms involved are still poorly understood. Exosomes have emerged as important mediators of intercellular communication in cancer. They mediate horizontal transfer of microRNAs (miRs), mRNAs and proteins, thus affecting breast cancer progression. Differential expression profile analysis identified three miRs (miRs -21, -378e, and -143) increased in exosomes from CAFs as compared from normal fibroblasts. Immunofluorescence indicated that exosomes may be transferred from CAFs to breast cancer cells, releasing their cargo miRs. Breast cancer cells (BT549, MDA-MB-231, and T47D lines) exposed to CAF exosomes or transfected with those miRs exhibited a significant increased capacity to form mammospheres, increased stem cell and epithelial-mesenchymal transition (EMT) markers, and anchorage-independent cell growth. These effects were reverted by tr...

Cancer-associated fibroblasts (CAFs) are the major components of the tumor microenvironment. They may drive tumor progression, although the mechanisms involved are still poorly understood. Exosomes have emerged as important mediators of intercellular communication in cancer. They mediate horizontal transfer of microRNAs (miRs), mRNAs and proteins, thus affecting breast cancer progression. Differential expression profile analysis identified three miRs (miRs -21, -378e, and -143) increased in exosomes from CAFs as compared from normal fibroblasts. Immunofluorescence indicated that exosomes may be transferred from CAFs to breast cancer cells, releasing their cargo miRs. Breast cancer cells (BT549, MDA-MB-231, and T47D lines) exposed to CAF exosomes or transfected with those miRs exhibited a significant increased capacity to form mammospheres, increased stem cell and epithelial-mesenchymal transition (EMT) markers, and anchorage-independent cell growth. These effects were reverted by tr...

Reactive stromal cells are an integral part of tumor microenvironment (TME) and interact with cancer cells to regulate their growth. Although targeting stromal cells could be a viable therapy to regulate the communication between TME and cancer cells, identification of stromal targets that make cancer cells vulnerable has remained challenging and elusive. Here, we identify a previously unrecognized mechanism whereby metabolism of reactive stromal cells is reprogrammed through an upregulated glutamine anabolic pathway. This dysfunctional stromal metabolism confers atypical metabolic flexibility and adaptive mechanisms in stromal cells, allowing them to harness carbon and nitrogen from noncanonical sources to synthesize glutamine in nutrient-deprived conditions existing in TME. Using an orthotopic mouse model for ovarian carcinoma, we find that co-targeting glutamine synthetase in stroma and glutaminase in cancer cells reduces tumor weight, nodules, and metastasis. We present a synthe...

The growth and progression of solid tumors involves dynamic cross-talk between cancer epithelium and the surrounding microenvironment. To date, molecular profiling has largely been restricted to the epithelial component of tumors; therefore, features underpinning the persistent protumorigenic phenotype of the tumor microenvironment are unknown. Using whole-genome bisulfite sequencing, we show for the first time that cancer-associated fibroblasts (CAFs) from localized prostate cancer display remarkably distinct and enduring genome-wide changes in DNA methylation, significantly at enhancers and promoters, compared to nonmalignant prostate fibroblasts (NPFs). Differentially methylated regions associated with changes in gene expression have cancer-related functions and accurately distinguish CAFs from NPFs. Remarkably, a subset of changes is shared with prostate cancer epithelial cells, revealing the new concept of tumor-specific epigenome modifications in the tumor and its microenviron...

Recent genomic studies have identified subtypes of uterine leiomyoma (LM) with distinctive genetic alterations. Here, we report the elucidation of the biological characteristics of the two most prevalent uterine leiomyoma subtypes, MED12-mutant (MED12-LM) and HMGA2-overexpressing (HMGA2-LM) uterine leiomyomas. Because each tumor carries only one genetic alteration, both subtypes are considered to be monoclonal. Approximately 90% of cells in HMGA2-uterine leiomyoma were smooth muscle cells (SMC) with HMGA2 overexpression. In contrast, MED12-LM consisted of similar numbers of SMC and non-SMC, which were mostly tumor-associated fibroblasts (TAF). Paradoxically, TAF carried no mutations in MED12, suggesting an interaction between SMC and TAF to coordinate their growth. The higher amount of extracellular matrix in MED12-LM than HMGA2-LM was partially due to the high concentration of collagen-producing TAF. SMC growth in a xenograft assay was driven by progesterone in both uterine leiomyo...

The hypothesis that microvesicle (MV)-mediated microRNA transfer converts non-cancer stem cells into cancer stem cells (CSCs) leading to therapy resistance remains poorly investigated. Here we provide direct evidence supporting this hypothesis, by demonstrating how MV derived from cancer associated fibroblasts (CAF) transfer miR-221 to promote hormonal therapy resistance (HTR) in models of luminal breast cancer. We determined that CAF-derived MV horizontally transferred miR221 to tumor cells and, in combination with hormone therapy activated an ERlo/Notchhi feed-forward loop responsible for the generation of CD133hi CSC. Importantly, MV from patients with HTR metastatic disease expressed high levels of miR221. We further determined that the IL6-pStat3 pathway in promoted the biogenesis of onco-miR-221hi CAF MV and established stromal CSC niches in experimental and patient-derived breast cancer models. Co-injection of patient-derived CAF from bone metastases led to de novo HTR tumors...

Stromal Derived Factor-1α (SDF-1α) and its cognate receptor CXCR4 play a key role in mediating breast cancer cell invasion and metastasis. Therefore, drugs able to inhibit CXCR4 activation may add critical tools to reduce tumor progression, especially in the most aggressive form of the breast cancer disease. Peroxisome Proliferator-Activated Receptor (PPAR) γ, a member of the nuclear receptor superfamily, has been found to downregulate CXCR4 gene expression in different cancer cells, however the molecular mechanism underlying this effect is not fully understood. Here, we identified a novel PPARγ-mediated mechanism that negatively regulates CXCR4 expression in both epithelial and stromal breast cancer cells. We found that ligand-activated PPARγ downregulated CXCR4 transcriptional activity through the recruitment of the silencing mediator of retinoid and thyroid hormone receptor (SMRT) corepressor onto a newly identified PPAR response element (PPRE) within the CXCR4 promoter in breast...

Autophagy is a cellular homeostatic mechanism where proteins and organelles are digested and recycled to provide an alternative source of building blocks and energy to cells. The role of autophagy in cancer microenvironment is still poorly understood. Here, we present a microfluidic system allowing monitoring of the crosstalk between single cells. We used this system to study how tumor cells induced autophagy in the stromal niche. Firstly, we could confirm that transforming growth factor β1 (TGFβ1) secreted from breast tumor cells is a paracrine mediator of tumor-stroma interaction leading to the activation of autophagy in the stroma component fibroblasts. Through proof of concept experiments using TGFβ1 as a model factor, we could demonstrate real time monitoring of autophagy induction in fibroblasts by single tumor cells. Retrieval of individual tumor cells from the microfluidic system and their subsequent genomic analysis was possible, allowing us to determine the nature of the f...

Cancer-associated fibroblasts (CAF) have been suggested to originate from mesenchymal stromal cells (MSC), but their relationship to MSC is not clear. Here we have isolated from primary human neuroblastoma (NB) tumors a population of αFAP- and FSP-1-expressing CAF that share phenotypic and functional characteristics with bone marrow-derived MSC (BM-MSC). Analysis of human NB tumors also confirmed the presence of αFAP- and FSP-1-positive cells in the tumor stroma, and their presence correlated with that of M2 tumor-associated macrophages. These cells (designated CAF-MSC) enhanced in vitro NB cell proliferation, survival, and resistance to chemotherapy and stimulated NB tumor engraftment and growth in immunodeficient mice, indicating an effect independent of the immune system. The pro-tumorigenic activity of MSC in vitro and in xenografted mice was dependent on the co-activation of JAK2/STAT3 and MEK/ERK1/2 in NB cells. In a mouse model of orthotopically implanted NB cells, inhibition...

Inhibitors of bromodomain and extraterminal domain (BET) proteins, a family of chromatin reader proteins, have therapeutic efficacy against various malignancies. However, the detailed mechanisms underlying the anti-tumor effects in distinct tumor types remain elusive. Here, we show a novel antitumor mechanism of BET inhibition in pancreatic ductal adenocarcinoma (PDAC). We found that JQ1, a BET inhibitor, decreased desmoplastic stroma, a hallmark of PDAC, and suppressed the growth of patient-derived tumor xenografts (PDX) of PDACs. In vivo antitumor effects of JQ1 were not always associated with the JQ1 sensitivity of respective PDAC cells, and were rather dependent on the suppression of tumor-promoting activity in cancer-associated fibroblasts (CAFs). JQ1 inhibited Hedgehog and TGF-β pathways as potent regulators of CAF activation and suppressed the expression of α-SMA, extracellular matrix, cytokines, and growth factors in human primary CAFs. Consistently, conditioned media (CM) f...

Lysyl Oxidase-like 2 (LOXL2), a member of the lysyl oxidase family of amine oxidases is known to be important in normal tissue development and homeostasis, as well as the onset and progression of solid tumors. Here we tested the anti-tumor properties of two generations of novel small molecule LOXL2 inhibitor in the MDA-MB-231 human model of breast cancer. We confirmed a functional role for LOXL2 activity in the progression of primary breast cancer. Inhibition of LOXL2 activity inhibited the growth of primary tumors and reduced primary tumor angiogenesis. Dual inhibition of LOXL2 and LOX showed a greater effect and also led to a lower overall metastatic burden in the lung and liver. Our data provides the first evidence to support a role for LOXL2 specific small molecule inhibitors as a potential therapy in breast cancer.

Stromal cells play a central role in the regulation of tumor angiogenesis. Recent studies have shown that stromal myofibroblasts [cancer-associated fibroblasts (CAFs)] actively promote tumor growth and enhance tumor angiogenesis in many types of adult carcinomas. To evaluate the role CAFs play in neuroblastoma (NB) angiogenesis and investigate their relationship to stromal Schwann cells, we quantified CAFs in 60 primary NB tumors and in a novel NB xenograft model in which murine Schwann cells were induced to infiltrate into the tumor stroma. Tumor sections were examined for presence of microvascular proliferation (MVP), a hallmark of tumor angiogenesis. CAFs were characterized by positive immunostaining for α-smooth muscle actin (α-SMA) and were distinguished from pericytes by staining negatively for high-MW caldesmon (hCD). α-SMA positive cells were quantified and CAF number was defined as high when >1.0% of the area was positive for α-SMA. Associations between high CAF number, MVP, and established clinico-pathologic features were analyzed. High numbers of CAFs were strongly associated with SS-poor histopathology and MVP. Thirty-seven (80%) of the 46 SS-poor tumors had high numbers of CAFs in the tumor stroma compared to only 2 (14%) of the 14 SS-rich/dominant tumors (p<0.001). Of the 37 tumors with MVP, 33 (89%) had high number of CAFs compared to 9 (40%) of the 22 tumors without MVP (p <0.001). In the NB xenografts with infiltrating stromal Schwann cells (n=10), the number of CAF/mm2 was ~7-fold less than in the control xenografts that lacked stromal Schwann cells (n=9) (mean of 51 ± 30 vs 368 ± 105, respectively; p<0.001). Thus, CAFs were inversely associated with the presence of Schwann cells, suggesting that Schwann cells may prevent the accumulation and activation of fibroblasts. A deeper understanding of the role CAFs play in NB angiogenesis may guide future development of stroma-directed therapeutic strategies.