Conditional activation of FGFR1 in the prostate epithelium induces angiogenesis with concomitant differential regulation of Ang-1 and Ang-2

A Transformable Specific-Responsive Peptide for One-Step Synergistic Therapy of Bladder Cancer

Synergistic therapy has shown greater advantages compared with monotherapy. However, the complex multiple-administration plan and potential side effects limit its clinical application. A transformable specific-responsive peptide (TSRP) is utilized to one-step achieve synergistic therapy integrating anti-tumor, anti-angiogenesis and immune response. The TSRP is composed of: i) Recognition unit could specifically target and inhibit the biological function of FGFR-1; ii) Transformable unit could self-assembly and trigger nanofibers formation; iii) Reactive unit could specifically cleaved by MMP-2/9 in tumor micro-environment; iv) Immune unit, stimulate the release of immune cells when LTX-315 (Immune-associated oncolytic peptide) exposed. Once its binding to FGFR-1, the TSRP could cleaved by MMP-2/9 to form the nanofibers on the cell membrane, with a retention time of up to 12 h. Through suppressing the phosphorylation levels of ERK 1/2 and PI3K/AKT signaling pathways downstream of FGFR-1, the TSRP significant inhibit the growth of tumor cells and the formation of angioginesis. Furthermore, LTX-315 is exposed after TSRP cleavage, resulting in Calreticulin activation and CD8+ T cells infiltration. All above processes together contribute to the increasing survival rate of tumor-bearing mice by nearly 4-folds. This work presented a unique design for the biological application of one-step synergistic therapy of bladder cancer.

Nesting and fate of transplanted stem cells in hypoxic/ischemic injured tissues: The role of HIF1α/sirtuins and downstream molecular interactions

The nesting mechanisms and programming for the fate of implanted stem cells in the damaged tissue have been critical issues in designing and achieving cell therapies. The fracture site can induce senescence or apoptosis based on the surrounding harsh conditions, hypoxia, and oxidative stress (OS). Respiration deficiency, disruption in energy metabolism, and consequently OS induction change the biophysical, biochemical, and cellular components of the native tissue. Additionally, the homeostatic molecular players and cell signaling might be changed. Despite all aforementioned issues, in the native stem cell niche, physiological hypoxia is not toxic; rather, it is vitally required for homing, self-renewal, and differentiation. Hence, the key macromolecular players involved in the support of stem cell survival and re-adaptation to a new dysfunctional niche must be understood for managing the cell therapy outcome. Hypoxia-inducible factor 1-alpha is the master transcriptional regulator, involved in the cell response to hypoxia and the adaptation of stem cells to a new niche. This protein is regulated by interaction with sirtuins. Sirtuins are highly conserved NAD+-dependent enzymes that monitor the cellular energy status and modulate gene transcription, genome stability, and energy metabolism in response to environmental signals to modulate the homing and fate of stem cells. Herein, new insights into the nesting of stem cells in hypoxic-ischemic injured tissues were provided and their programming in a new dysfunctional niche along with the involved complex macromolecular players were critically discussed.

Immunovascular microenvironment in relation to prognostic heterogeneity of WNT/β-catenin-activated hepatocellular carcinoma

AIM

WNT/β-catenin-activated hepatocellular carcinoma (W/B subclass HCC) is considered a molecularly homogeneous entity and has been linked to resistance to immunotherapy. However, recent studies have indicated possible heterogeneity in the immunovascular microenvironment in this subclass. We set out to test the hypothesis that specific immunovascular features might stratify W/B subclass HCCs into tumors having distinct aggressive natures.

METHODS

In this study, we analyzed 352 resected HCCs including 78 immunohistochemically defined W/B subclass HCCs. The density of tumor-infiltrating CD3⁺ T cells and the area ratio of vessels encapsulating tumor clusters (VETC) were calculated on tissue specimens. The gene expressions of angiogenic factors were measured by quantitative reverse transcription-polymerase chain reaction. Disease-free survival (DFS) was assessed using multivariable Cox regression analyses.

RESULTS

The T-cell density of W/B subclass HCCs was regionally heterogenous within tumor tissues, and focally reduced T-cell density was observed in areas with VETC. VETC-positivity (defined as VETC area ratio greater than 1%) was inversely associated with T-cell infiltration in both W/B subclass and non-W/B subclass HCCs. Fibroblast growth factor 2 (FGF2) gene expression was higher in W/B subclass than in non-W/B subclass HCCs. The VETC-positivity and low T-cell density correlated with increased expression of FGF2 in W/B subclass HCCs. Additionally, VETC-positive HCCs showed significantly shorter DFS in W/B subclass HCCs.

CONCLUSIONS

In conclusion, the immune and vascular microenvironments are interrelated and are also correlated with clinicopathological heterogeneity in W/B subclass HCC. These results could inform clinical practice and translational research on the development of therapeutic stratification of HCCs.

The FGF/FGFR system in the physiopathology of the prostate gland

Fibroblast growth factors (FGFs) are a family of proteins possessing paracrine, autocrine, or endocrine functions in a variety of biological processes, including embryonic development, angiogenesis, tissue homeostasis, wound repair, and cancer. Canonical FGFs bind and activate tyrosine kinase FGF receptors (FGFRs), triggering intracellular signaling cascades that mediate their biological activity. Experimental evidence indicates that FGFs play a complex role in the physiopathology of the prostate gland that ranges from essential functions during embryonic development to modulation of neoplastic transformation. The use of ligand- and receptor-deleted mouse models has highlighted the requirement for FGF signaling in the normal development of the prostate gland. In adult prostate, the maintenance of a functional FGF/FGFR signaling axis is critical for organ homeostasis and function, as its disruption leads to prostate hyperplasia and may contribute to cancer progression and metastatic dissemination. Dissection of the molecular landscape modulated by the FGF family will facilitate ongoing translational efforts directed toward prostate cancer therapy.

Role of angiopoietin-2 in the cardioprotective effect of fibroblast growth factor 21 on ischemia/reperfusion-induced injury in H9c2 cardiomyocytes

Fibroblast growth factor 21 (FGF21) exerts a protective effect in ischemia/reperfusion (I/R)-induced cardiac injury. However, the exact molecular mechanism underlying the FGF21 action remains unclear. The present study aimed to evaluate the role of angiopoietin-2 (Angpt2) in the cardioprotective effect of FGF21. For this purpose, the H9C2 cell line was subjected to simulated I/R or aerobic conditions with or without FGF21 administration. Certain groups were also transfected with Angpt2 small interfering RNA (siRNA). Cell viability, apoptosis rate and cell migration were examined, and the expression levels of Angpt2, glucose transporter 1 (GLUT1) and caspase-3 were measured by quantitative polymerase chain reaction (qPCR) and western blot analyses. The results demonstrated that FGF21 administration suppressed apoptosis and increased the cell migration ability following I/R-induced injury. qPCR and western blot data showed a decreased level of GLUT1 after I/R-induced injury, which was reversed by FGF21 administration. Furthermore, inhibition of Angpt2 expression using siRNA enhanced the cardioprotective effect of FGF21 by upregulation of GLUT1. In conclusion, FGF21 administration protected against I/R-induced injury in cardiomyocytes, and further inhibition of Angpt2 with FGF21 administration induced the expression of GLUT1, which may promote the energy metabolism in cardiomyocytes, consequently resulting in a more efficient cardioprotective effect. These results suggested that FGF21 administration and inhibition of Angpt2 could be a novel therapeutic approach for I/R-induced cardiac injury.

Mesenchymal Stem Cell Migration and Proliferation Are Mediated by Hypoxia-Inducible Factor-1α Upstream of Notch and SUMO Pathways

Mesenchymal stem cells (MSCs) are effective in treating several pathologies. We and others have demonstrated that hypoxia or hypoxia-inducible factor 1 alpha (HIF-1α) stabilization improves several MSC functions, including cell adhesion, migration, and proliferation, thereby increasing their therapeutic potential. To further explore the mechanisms induced by HIF-1α in MSCs, we studied its relationship with Notch signaling and observed that overexpression of HIF-1α in MSCs increased protein levels of the Notch ligands Jagged 1-2 and Delta-like (Dll)1, Dll3, and Dll4 and potentiated Notch signaling only when this pathway was activated. Crosstalk between HIF and Notch resulted in Notch-dependent migration and spreading of MSCs, which was abolished by γ-secretase inhibition. However, the HIF-1-induced increase in MSC proliferation was independent of Notch signaling. The ubiquitin family member, small ubiquitin-like modifier (SUMO), has important functions in many cellular processes and increased SUMO1 protein levels have been reported in hypoxia. To investigate the potential involvement of SUMOylation in HIF/Notch crosstalk, we measured general SUMOylation levels and observed increased SUMOylation in HIF-1-expressing MSCs. Moreover, proliferation and migration of MSCs were reduced in the presence of a SUMOylation inhibitor, and this effect was particularly robust in HIF-MSCs. Immunoprecipitation studies demonstrated SUMOylation of the intracellular domain of Notch1 (N1ICD) in HIF-1-expressing MSCs, which contributed to Notch pathway activation and resulted in increased levels of N1ICD nuclear translocation as assessed by subcellular fractionation. SUMOylation of N1ICD was also observed in HEK293T cells with stabilized HIF-1α expression, suggesting that this is a common mechanism in eukaryotic cells. In summary, we describe, for the first time, SUMOylation of N1ICD, which is potentiated by HIF signaling. These phenomena could be relevant for the therapeutic effects of MSCs in hypoxia or under conditions of HIF stabilization.

FGFR1 Induces Glioblastoma Radioresistance through the PLCγ/Hif1α Pathway

FGF2 signaling in glioblastoma induces resistance to radiotherapy, so targeting FGF2/FGFR pathways might offer a rational strategy for tumor radiosensitization. To investigate this possibility, we evaluated a specific role for FGFR1 in glioblastoma radioresistance as modeled by U87 and LN18 glioblastomas in mouse xenograft models. Silencing FGFR1 decreased radioresistance in a manner associated with radiation-induced centrosome overduplication and mitotic cell death. Inhibiting PLCγ (PLCG1), a downstream effector signaling molecule for FGFR1, was sufficient to produce similar effects, arguing that PLCγ is an essential mediator of FGFR1-induced radioresistance. FGFR1 silencing also reduced expression of HIF1α, which in addition to its roles in hypoxic responses exerts an independent effect on radioresistance. Finally, FGFR1 silencing delayed the growth of irradiated tumor xenografts, in a manner that was associated with reduced HIF1α levels but not blood vessel alterations. Taken together, our results offer a preclinical proof of concept that FGFR1 targeting can degrade radioresistance in glioblastoma, a widespread problem in this tumor, prompting clinical investigations of the use of FGFR1 inhibitors for radiosensitization. Cancer Res; 76(10); 3036-44. ©2016 AACR.

Hyperactivated FRS2α-mediated signaling in prostate cancer cells promotes tumor angiogenesis and predicts poor clinical outcome of patients

Metastasis of tumors requires angiogenesis, which is comprised of multiple biological processes that are regulated by angiogenic factors. The fibroblast growth factor (FGF) is a potent angiogenic factor and aberrant FGF signaling is a common property of tumors. Yet, how the aberration in cancer cells contributes to angiogenesis in the tumor is not well understood. Most studies of its angiogenic signaling mechanisms have been in endothelial cells. FGF receptor substrate 2α (FRS2α) is an FGF receptor-associated protein required for activation of downstream signaling molecules that include those in the mitogen-activated protein and AKT kinase pathways. Herein, we demonstrated that overactivation and hyperactivity of FRS2α, as well as overexpression of cJUN and HIF1α, were positively correlated with vessel density and progression of human prostate cancer (PCa) toward malignancy. We also demonstrate that FGF upregulated the production of vascular endothelial growth factor A mainly by increasing expression of cJUN and HIF1α. This then promoted recruitment of endothelial cells and vessel formation for the tumor. Tumor angiogenesis in mouse PCa tissues was compromised by tissue-specific ablation of Frs2α in prostate epithelial cells. Depletion of Frs2α expression in human PCa cells and in a preclinical xenograft model, MDA PCa 118b, also significantly suppressed tumor angiogenesis accompanied with decreased tumor growth in the bone. The results underscore the angiogenic role of FRS2α-mediated signaling in tumor epithelial cells in angiogenesis. They provide a rationale for treating PCa with inhibitors of FGF signaling. They also demonstrate the potential of overexpressed FRS2α as a biomarker for PCa diagnosis, prognosis and response to therapies.

The search for biomarkers to direct antiangiogenic treatment in epithelial ovarian cancer

Antiangiogenic agents have demonstrated improved progression-free survival in women with primary and recurrent epithelial ovarian cancer (EOC). Biomarkers that predict outcomes in patients treated with antiangiogenic agents are being investigated to rationally direct therapy for women most likely to benefit from these agents. Among the most promising plasma-based biomarkers are vascular endothelial growth factor (VEGF)-A, fibroblast growth factor, platelet-derived growth factor, angiopoietin-2, and VEGF receptor-2. While these biomarkers have been correlated with prognosis, they have not been shown to predict benefit, specifically from anti-VEGF therapy, highlighting the need for alternative biomarkers, including molecular and clinical factors, which may be predictive of outcome in women with ovarian cancer treated with antiangiogenic agents. Biomarkers are currently being investigated as secondary outcomes in several ongoing phase II and phase III clinical trials of antiangiogenic agents in patients with EOC. Molecular techniques, such as microarray analyses, and imaging techniques, such as dynamic contrast-enhanced magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography, are also being explored in this field. In this review, we provide a comprehensive overview of current biomarker research, with an emphasis on angiogenic biomarkers associated with EOC.

Ligand-associated ERBB2/3 activation confers acquired resistance to FGFR inhibition in FGFR3-dependent cancer cells

Somatic alterations of Fibroblast Growth Factor Receptors (FGFRs) have been described in a wide range of malignancies. A number of anti-FGFR therapies are currently under investigation in clinical trials for subjects with FGFR gene amplifications, mutations and translocations. Here, we develop cell line models of acquired resistance to FGFR inhibition by exposure of cell lines harboring FGFR3 gene amplification and translocation to the selective FGFR inhibitor BGJ398 and multi-targeted FGFR inhibitor ponatinib. We show that the acquisition of resistance is rapid, reversible and characterized by an epithelial to mesenchymal transition (EMT) and a switch from dependency on FGFR3 to ERBB family members. Acquired resistance was associated with demonstrable changes in gene expression including increased production of ERBB2/3 ligands which were sufficient to drive resistance in the setting of FGFR3 dependency but not dependency on other FGFR family members. These data support the concept that activation of ERBB family members is sufficient to bypass dependency on FGFR3 and suggest that concurrent inhibition of these two pathways may be desirable when targeting FGFR3 dependent cancers.

Targeting fibroblast growth factor pathways in prostate cancer

Advanced prostate cancer carries a poor prognosis and novel therapies are needed. Research has focused on identifying mechanisms that promote angiogenesis and cellular proliferation during prostate cancer progression from the primary tumor to bone-the principal site of prostate cancer metastases. One candidate pathway is the fibroblast growth factor (FGF) axis. Aberrant expression of FGF ligands and FGF receptors leads to constitutive activation of multiple downstream pathways involved in prostate cancer progression including mitogen-activated protein kinase, phosphoinositide 3-kinase, and phospholipase Cγ. The involvement of FGF pathways in multiple mechanisms relevant to prostate tumorigenesis provides a rationale for the therapeutic blockade of this pathway, and two small-molecule tyrosine kinase inhibitors-dovitinib and nintedanib-are currently in phase II clinical development for advanced prostate cancer. Preliminary results from these trials suggest that FGF pathway inhibition represents a promising new strategy to treat castrate-resistant disease.

In vivo electroporation of constitutively expressed HIF-1α plasmid DNA improves neovascularization in a mouse model of limb ischemia

OBJECTIVE

Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that stimulates angiogenesis during tissue ischemia. In vivo electroporation (EP) enhances tissue DNA transfection. We hypothesized that in vivo EP of plasmid DNA encoding a constitutively expressed HIF-1α gene enhances neovascularization compared with intramuscular (IM) injection alone.

METHODS

Left femoral artery ligation was performed in mice assigned to three groups: (1) HIF-EP (n = 13); (2) HIF-IM (n = 14); and (3) empty plasmid (pVAX)-EP (n = 12). A single dose of HIF-1α or pVAX DNA (20 μL of 5 μg/μL each) was injected into the ischemic adductor muscle followed by EP (groups one and three). Mice in group two received IM injection of HIF-1α plasmid DNA alone. From preligation to days 0, 3, 7, 14, and 21 postligation, limb perfusion recovery quantified by laser Doppler perfusion imager, limb function, and limb necrosis were measured. On day 21, the surviving mice (4-5 per group) were sacrificed and adductor muscle tissues stained for necrosis using hematoxylin and eosin, capillary density (anti-CD31 antibodies), and collateral vessels via anti-α-smooth muscle actin antibodies.

RESULTS

In vivo EP of HIF-1α DNA significantly improved limb perfusion (HIF-EP: 1.03 ± 0.15 vs HIF-IM: 0.78 ± 0.064; P < .05, vs pVAX-EP: 0.41 ± 0.019; P < .001), limb functional recovery (HIF-EP: 3.5 ± 0.58 vs HIF-IM, 2.4 ± 1.14; P < .05, vs pVAX-EP: 2.4 ± 1.14; P < .001), and limb autoamputation on day 21 (HIF-EP: 77% ± 12% vs HIF-IM: 43% ± 14%; P < .05 vs pVAX-EP: 17% ± 11%; P < .01). Adductor muscle tissue necrosis decreased (HIF-EP: 20.7% ± 1.75% vs HIF-IM: 44% ± 3.73; P < .001, vs pVAX-EP: 60.05% ± 2.17%; P < .0001), capillary density increased (HIF-EP: 96.83 ± 5.72 vessels/high-powered field [hpf] vs HIF-IM: 62.87 ± 2.0 vessels/hpf; P < .001, vs pVAX-EP: 39.37 ± 2.76 vessels/hpf; P < .0001), collateral vessel formation increased (HI-EP: 76.33 ± 1.94 vessels/hpf vs HIF-IM: 37.5 ± 1.56 vessels/hpf; P < .0001, vs pVAX-EP: 18.5 ± 1.34 vessels/hpf; P < .00001), and the vessels were larger (HIF-EP: 15,521.67 ± 1298.16 μm(2) vs HIF-IM: 7788.87 ± 392.04 μm(2); P < .001 vs pVAX-EP: 4640.25 ± 614.01 μm(2); P < .0001).

CONCLUSIONS

In vivo EP-mediated delivery of HIF-1α plasmid DNA improves neovascularization in a mouse model of limb ischemia and is a potentially suitable nonviral, noninvasive intervention to facilitate therapeutic angiogenesis in critical limb ischemia.

The FGF/FGFR axis as a therapeutic target in breast cancer

Fibroblast growth factor receptor (FGFR) signaling is a vital component of both embryonic and postnatal mammary gland development, which has prompted researchers to investigate both its relevance to breast cancer and its potential as a therapeutic target. Deregulated FGFR signaling during breast cancer occurs through various mechanisms, including amplification of the receptor genes, aberrant ligand expression, receptor mutations and translocations. Recent experimental outcomes involving both animal models and human breast cancer cell lines have led to the initiation of multiple early clinical trials investigating the safety and efficacy of small molecule FGFR inhibitors. In this article we review both the most recent discoveries and the need for further investigation of the mechanisms through which FGF/FGFR signaling has emerged as an oncogenic driver.

The metalloproteinase ADAMTS1: a comprehensive review of its role in tumorigenic and metastatic pathways

As it was first characterized in 1997, the ADAMTS (A Disintegrin and Metalloprotease with ThromboSpondin motifs) metalloprotease family has been associated with many physiological and pathological conditions. Of the 19 proteases belonging to this family, considerable attention has been devoted to the role of its first member ADAMTS1 in cancer. Elevated ADAMTS1 promotes pro-tumorigenic changes such as increased tumor cell proliferation, inhibited apoptosis and altered vascularization. Importantly, it facilitates significant peritumoral remodeling of the extracellular matrix environment to promote tumor progression and metastasis. However, discrepancy exists, as several studies also depict ADAMTS1 as a tumor suppressor. This article reviews the current understanding of ADAMTS1 regulation and the consequence of its dysregulation in primary cancer and ADAMTS1-mediated pathways of cancer progression and metastasis.

Dose-related estrogen effects on gene expression in fetal mouse prostate mesenchymal cells

Developmental exposure of mouse fetuses to estrogens results in dose-dependent permanent effects on prostate morphology and function. Fetal prostatic mesenchyme cells express estrogen receptor alpha (ERα) and androgen receptors and convert stimuli from circulating estrogens and androgens into paracrine signaling to regulate epithelial cell proliferation and differentiation. To obtain mechanistic insight into the role of different doses of estradiol (E2) in regulating mesenchymal cells, we examined E2-induced transcriptomal changes in primary cultures of fetal mouse prostate mesenchymal cells. Urogenital sinus mesenchyme cells were obtained from male mouse fetuses at gestation day 17 and exposed to 10 pM, 100 pM or 100 nM E2 in the presence of a physiological concentration of dihydrotestosterone (0.69 nM) for four days. Gene ontology studies suggested that low doses of E2 (10 pM and 100 pM) induce genes involved in morphological tissue development and sterol biosynthesis but suppress genes involved in growth factor signaling. Genes involved in cell adhesion were enriched among both up-regulated and down-regulated genes. Genes showing inverted-U-shape dose responses (enhanced by E2 at 10 pM E2 but suppressed at 100 pM) were enriched in the glycolytic pathway. At the highest dose (100 nM), E2 induced genes enriched for cell adhesion, steroid hormone signaling and metabolism, cytokines and their receptors, cell-to-cell communication, Wnt signaling, and TGF- β signaling. These results suggest that prostate mesenchymal cells may regulate epithelial cells through direct cell contacts when estrogen level is low whereas secreted growth factors and cytokines might play significant roles when estrogen level is high.

Characterization of PAR1 and FGFR1 expression in invasive breast carcinomas: Prognostic significance

Breast cancer is the most common cause of cancer mortality among women worldwide. Among the several factors associated with breast cancer development, angiogenesis plays an essential role and has currently emerged as a potential diagnostic, prognostic and therapeutic target. Protease-activated receptor 1 (PAR1) and fibroblast growth factor receptor 1 (FGFR1) have important activities in tumor angiogenesis and progression. The aim of this study was to investigate the prognostic significance of these two receptors, hypothesising significant correlations between receptor expression in tumor angiogenesis and clinicopathological parameters customarily used in breast cancer prognosis and prediction. Formalin-fixed and paraffin-embedded samples of ductal invasive breast carcinomas were used to analyze the expression of PAR1 and FGFR1, in the tumor cells as well as in the tumor stroma, and further determine intratumoral microvessel density (iMVD) to quantify intratumoral angiogenesis. Correlations between PAR1 and FGFR1 expression in tumor cells and stroma, iMVD and several clinicopathological parameters and molecular markers used in breast cancer diagnosis have been addressed. The correlation between PAR1 and FGFR1 suggests an association of the two receptors with a more aggressive breast cancer phenotype and, consequently, a potential role during tumor progression. The results reported in the present study also emphasize the importance of microenvironmental factors in tumor progression, while precluding the positive association between iMVD and breast cancer aggressiveness.

Endothelial HIF-2α regulates murine pathological angiogenesis and revascularization processes

Localized tissue hypoxia is a consequence of vascular compromise or rapid cellular proliferation and is a potent inducer of compensatory angiogenesis. The oxygen-responsive transcriptional regulator hypoxia-inducible factor 2α (HIF-2α) is highly expressed in vascular ECs and, along with HIF-1α, activates expression of target genes whose products modulate vascular functions and angiogenesis. However, the mechanisms by which HIF-2α regulates EC function and tissue perfusion under physiological and pathological conditions are poorly understood. Using mice in which Hif2a was specifically deleted in ECs, we demonstrate here that HIF-2α expression is required for angiogenic responses during hindlimb ischemia and for the growth of autochthonous skin tumors. EC-specific Hif2a deletion resulted in increased vessel formation in both models; however, these vessels failed to undergo proper arteriogenesis, resulting in poor perfusion. Analysis of cultured HIF-2α-deficient ECs revealed cell-autonomous increases in migration, invasion, and morphogenetic activity, which correlated with HIF-2α-dependent expression of specific angiogenic factors, including delta-like ligand 4 (Dll4), a Notch ligand, and angiopoietin 2. By stimulating Dll4 signaling in cultured ECs or restoring Dll4 expression in ischemic muscle tissue, we rescued most of the HIF-2α-dependent EC phenotypes in vitro and in vivo, emphasizing the critical role of Dll4/Notch signaling as a downstream target of HIF-2α in ECs. These results indicate that HIF-1α and HIF-2α fulfill complementary, but largely nonoverlapping, essential functions in pathophysiological angiogenesis.

Control of tumor and microenvironment cross-talk by miR-15a and miR-16 in prostate cancer

The interaction between cancer cells and microenvironment has a critical role in tumor development and progression. Although microRNAs regulate all the major biological mechanisms, their influence on tumor microenvironment is largely unexplored. Here, we investigate the role of microRNAs in the tumor-supportive capacity of stromal cells. We demonstrated that miR-15 and miR-16 are downregulated in fibroblasts surrounding the prostate tumors of the majority of 23 patients analyzed. Such downregulation of miR-15 and miR-16 in cancer-associated fibroblasts (CAFs) promoted tumor growth and progression through the reduced post-transcriptional repression of Fgf-2 and its receptor Fgfr1, which act on both stromal and tumor cells to enhance cancer cell survival, proliferation and migration. Moreover, reconstitution of miR-15 and miR-16 impaired considerably the tumor-supportive capability of stromal cells in vitro and in vivo. Our data suggest a molecular circuitry in which miR-15 and miR-16 and their correlated targets cooperate to promote tumor expansion and invasiveness through the concurrent activity on stromal and cancer cells, thus providing further support to the development of therapies aimed at reconstituting miR-15 and miR-16 in advanced prostate cancer.

Comparison of intensity-modulated continuous-wave lasers with a chirped modulation frequency to pulsed lasers for photoacoustic imaging applications

Using a Green's function solution to the photoacoustic wave equation, we compare intensity-modulated continuous-wave (CW) lasers with a chirped modulation frequency to pulsed lasers for photoacoustic imaging applications. Assuming the same transducer is used in both cases, we show that the axial resolution is identical and is determined by the transducer and material properties of the object. We derive a simple formula relating the signal-to-noise ratios (SNRs) of the two imaging systems that only depends on the fluence of each pulse and the time-bandwidth product of the chirp pulse. We also compare the SNR of the two systems assuming the fluence is limited by the American National Standards Institute (ANSI) laser safety guidelines for skin. We find that the SNR is about 20 dB to 30 dB larger for pulsed laser systems for reasonable values of the parameters. However, CW diode lasers have the advantage of being compact and relatively inexpensive, which may outweigh the lower SNR in many applications.

Hemodynamic and metabolic diffuse optical monitoring in a mouse model of hindlimb ischemia

Murine hindlimb ischemia is a useful model for investigation of the mechanisms of peripheral arterial disease and for understanding the role of endothelial cells and generic factors affecting vascular regeneration or angiogenesis. To date, important research with these models has explored tissue reperfusion following ischemia with Laser Doppler methods, methods which provide information about superficial (~mm) vascular regeneration. In this work, we employ diffuse correlation spectroscopy (DCS) and diffuse optical spectroscopy (DOS) in mice after hindlimb ischemia. We hypothesize that vascular re-growth is not uniform in tissue, and therefore, since diffuse optical methods are capable of probing deep tissues, that the diffuse optics approach will provide a more complete picture of the angiogenesis process throughout the whole depth profile of the limb. Besides increased depth penetration, the combined measurements of DCS and DOS enable all-optical, noninvasive, longitudinal monitoring of tissue perfusion and oxygenation that reveals the interplay between these hemodynamic parameters during angiogenesis. Control mice were found to reestablish 90% of perfusion and oxygen consumption during this period, but oxygen saturation in the limb only partially recovered to about 30% of its initial value. The vascular recovery of mice with endothelial cell-specific deletion of HIF-2α was found to be significantly impaired relative to control mice, indicating that HIF-2α is important for endothelial cell functions in angiogenesis. Comparison of DOS/DCS measurements to parallel measurements in the murine models using Laser Doppler Flowmetry reveal differences in the reperfusion achieved by superficial versus deep tissue during neoangiogenesis; findings from histological analysis of blood vessel development were further correlated with these differences. In general, the combination of DCS and DOS enables experimenters to obtain useful information about oxygenation, metabolism, and perfusion throughout the limb. The results establish diffuse optics as a practical noninvasive method to evaluate the role of transcription factors, such as the endothelial cell-specific HIF-2α, in genetic ally modified mice.

Roles of fibroblast growth factor receptors in carcinogenesis

The fibroblast growth factor receptors (FGFR) play essential roles both during development and in the adult. Upon ligand binding, FGFRs induce intracellular signaling networks that tightly regulate key biological processes, such as cell proliferation, survival, migration, and differentiation. Deregulation of FGFR signaling can thus alter tissue homeostasis and has been associated with several developmental syndromes as well as with many types of cancer. In human cancer, FGFRs have been found to be deregulated by multiple mechanisms, including aberrant expression, mutations, chromosomal rearrangements, and amplifications. In this review, we will give an overview of the main FGFR alterations described in human cancer to date and discuss their contribution to cancer progression.

Modulation of the vitamin D3 response by cancer-associated mutant p53

The p53 gene is mutated in many human tumors. Cells of such tumors often contain abundant mutant p53 (mutp53) protein, which may contribute actively to tumor progression via a gain-of-function mechanism. We applied ChIP-on-chip analysis and identified the vitamin D receptor (VDR) response element as overrepresented in promoter sequences bound by mutp53. We report that mutp53 can interact functionally and physically with VDR. Mutp53 is recruited to VDR-regulated genes and modulates their expression, augmenting the transactivation of some genes and relieving the repression of others. Furthermore, mutp53 increases the nuclear accumulation of VDR. Importantly, mutp53 converts vitamin D into an antiapoptotic agent. Thus, p53 status can determine the biological impact of vitamin D on tumor cells.

Fibroblast growth factor signalling: from development to cancer

Fibroblast growth factors (FGFs) and their receptors control a wide range of biological functions, regulating cellular proliferation, survival, migration and differentiation. Although targeting FGF signalling as a cancer therapeutic target has lagged behind that of other receptor tyrosine kinases, there is now substantial evidence for the importance of FGF signalling in the pathogenesis of diverse tumour types, and clinical reagents that specifically target the FGFs or FGF receptors are being developed. Although FGF signalling can drive tumorigenesis, in different contexts FGF signalling can mediate tumour protective functions; the identification of the mechanisms that underlie these differential effects will be important to understand how FGF signalling can be most appropriately therapeutically targeted.

Novel phosphotyrosine targets of FGFR2IIIb signaling

In partnership exclusively with the epithelial FGFR2IIIb isotype and a structurally-specific heparan sulfate motif, stromal-derived FGF7 delivers both growth-promoting and growth-limiting differentiation signals to epithelial cells that promote cellular homeostasis between stromal and epithelial compartments. Intercompartmental homeostasis supported by FGF7/FGFR2IIIb is subverted in many solid epithelial tumors. The normally mesenchymal-derived homologue FGFR1 drives proliferation and a progressive tumor-associated phenotype when it appears ectopically in epithelial cells. In order to understand the mechanism underlying the unique biological effects of FGFR2IIIb, we developed an inducible FGFR2IIIb expression system that is specifically dependent on FGF7 for activation in an initially unresponsive cell line to avoid selection for only the growth-promoting aspects of FGFR2IIIb signaling. We then determined FGF7/FGFR2IIIb signaling-specific tyrosine phosphorylated proteins within 5 min after FGF7 stimulation by phosphopeptide immunoaffinity purification and nano-LC-MS/MS. The FGF7/FGFR2 pair caused tyrosine phosphorylation of multiple proteins that have been implicated in the growth stimulating activities of FGFR1 that included multi-substrate organizers FRS2alpha and IRS4, ERK2 and phosphatases SHP2 and SHIP2. It uniquely phosphorylated CDK2 and phosphatase PTPN18 on sites involved in the attenuation of cell proliferation, and several factors that maintain nuclear-cytosolic relationships (emerin and LAP2), protein structure and other cellular fine structures as well as some proteins of unknown functions. Several of the FGF7/FGFR2IIIb-specific targets have been associated with maintenance of function and tumor suppression and disruption in tumors. In contrast, a number of pTyr substrates associated with FGF2/FGFR1 that are generally associated with intracellular Ca(2+)-phospholipid signaling, membrane and cytoskeletal plasticity, cell adhesion, migration and the tumorigenic phenotype were not observed with FGF7/FGFR2IIIb. Our findings provide specific downstream targets for dissection of causal relationships underlying the distinct role of FGF7/FGFR2IIIb signaling in epithelial cell homeostasis.

FGFR3 mutations in prostate cancer: association with low-grade tumors

Prostate cancer is the second cause of cancer-related death in men of the Western World. The role of FGFR3 and its abnormalities in prostate cancer are not known. FGFR3 mutations have been reported in some human tumors. Few studies have analyzed the mutations of FGFR3 in prostate tumors, and no mutations have been previously reported. Prevalence of FGFR3 somatic mutations was investigated in a series of prostate tumors. The presence of other tumors in these patients, including urothelial, skin, colon, and lung neoplasms, was recorded. Mutational analysis of exons 7, 10, and 15 of FGFR3 revealed 9 mutations in the 112 prostate tumors studied (8%). Most of them consisted of the missense change S249C. The prevalence of mutations in tumors with combined Gleason score=6 is 18% (8/45) compared to 3% (1/36) for tumors with grade=7, and 0% (0/31) for those with grade >or=8 and metastases (P=0.007). The frequency of FGFR3 mutations in autopsy and biopsy samples was 6 and 9%, respectively. The prevalence of FGFR3 mutations in prostate tumors from patients with only prostate cancer was 2% compared to 23% in prostate tumors from patients with other associated neoplasms (P=0.001). This is the first report of molecular changes of FGFR3 in prostate cancer. This gene does not seem to be central to the pathogenesis of prostate cancer, but it is significantly associated with a subgroup of low-grade prostate tumors, and with the finding of other tumors, mainly arising in bladder and skin.

Endothelial deletion of hypoxia-inducible factor-2alpha (HIF-2alpha) alters vascular function and tumor angiogenesis

Hypoxia-inducible factor-2alpha (HIF-2alpha) is highly expressed in embryonic vascular endothelial cells (ECs) and activates the expression of target genes whose products modulate vascular function and angiogenesis. In this report, we describe a genetic model designed to test the physiologic consequences of deleting HIF-2alpha in murine endothelial cells. Surprisingly, mice with HIF-2alpha-deficient ECs developed normally but displayed a variety of phenotypes, including increased vessel permeability, aberrant endothelial cell ultrastructure, and pulmonary hypertension. Moreover, these animals exhibited defective tumor angiogenesis associated with increased hypoxic stress and tumor cell apoptosis. Immortalized HIF-2alpha-deficient ECs displayed decreased adhesion to extracellular matrix proteins and expressed reduced levels of transcripts encoding fibronectin, integrins, endothelin B receptor, angiopoietin 2, and delta-like ligand 4 (Dll4). Together, these data identify unique cell-autonomous functions for HIF-2alpha in vascular endothelial cells.

Paths of FGFR-driven tumorigenesis

Fibroblast growth factor receptors (FGFRs) comprise a subfamily of receptor tyrosine kinases (RTKs) that are master regulators of a broad spectrum of cellular and developmental processes, including apoptosis, proliferation, migration and angiogenesis. Due to their broad impact, FGFRs and other RTKs are highly regulated and normally only basally active. Deregulation of FGFR signaling by activating mutations or ligand/receptor overexpression could allow these receptors to become constitutively active, leading to cancer development, including both hematopoietic and solid tumors, such as breast, bladder and prostate carcinomas. In this review, we focus on potential modes of FGFR-mediated tumorigenesis, in particular, the role of FGFR1 during prostate cancer progression.

Pleiotropic biological activities of alternatively spliced TMPRSS2/ERG fusion gene transcripts

TMPRSS2/ERG gene fusions are found in the majority of prostate cancers; however, there is significant heterogeneity in the 5' region of the alternatively spliced fusion gene transcripts. We have found that there is also significant heterogeneity within the coding exons as well. There is variable inclusion of a 72-bp exon and other novel alternatively spliced isoforms. To assess the biological significance of these alternatively spliced transcripts, we expressed various transcripts in primary prostatic epithelial cells (PrEC) and in an immortalized PrEC line, PNT1a. The fusion gene transcripts promoted proliferation, invasion, and motility with variable activities that depended on the structure of the 5' region encoding the TMPRSS2/ERG fusion and the presence of the 72-bp exon. Cotransfection of different isoforms further enhanced biological activity, mimicking the situation in vivo, in which multiple isoforms are expressed. Finally, knockdown of the fusion gene in VCaP cells resulted in inhibition of proliferation in vitro and tumor progression in an in vivo orthotopic mice model. Our results indicate that TMPRSS2/ERG fusion isoforms have variable biological activities promoting tumor initiation and progression and are consistent with our previous clinical observations indicating that certain TMPRSS2/ERG fusion isoforms are significantly correlated with more aggressive disease.

Relationship between human tumour angiogenic profile and combretastatin-induced vascular shutdown: an exploratory study

Combretastatin-A4-phosphate (CA4P) acts most effectively against immature tumour vasculature. We investigated whether histological angiogenic profile can explain the differential sensitivity of human tumours to CA4P, by correlating the kinetic changes demonstrated by dynamic MRI (DCE-MRI) in response to CA4P, with tumour immunohistochemical angiogenic markers. Tissue was received from 24 patients (mean age 59, range 32-73, 18 women, 6 men). An angiogenic profile was performed using standard immunohistochemical techniques. Dynamic MRI data were obtained for the same patients before and 4 h after CA4P. Three patients showed a statistically significant fall in K(trans) following CA4P, and one a statistically significant fall in IAUGC(60). No statistically significant correlations were seen between the continuous or categorical variables and the DCE-MRI kinetic parameters other than between ang-2 and K(trans) (P=0.044). In conclusion, we found no strong relationships between changes in DCE-MRI kinetic variables following CA4P and the immunohistochemical angiogenic profile.

Inducible FGFR-1 activation leads to irreversible prostate adenocarcinoma and an epithelial-to-mesenchymal transition

Fibroblast Growth Factor Receptor-1 (FGFR1) is commonly overexpressed in advanced prostate cancer (PCa). To investigate causality, we utilized an inducible FGFR1 (iFGFR1) prostate mouse model. Activation of iFGFR1 with chemical inducers of dimerization (CID) led to highly synchronous, step-wise progression to adenocarcinoma that is linked to an epithelial-to-mesenchymal transition (EMT). iFGFR1 inactivation by CID withdrawal led to full reversion of prostatic intraepithelial neoplasia, whereas PCa lesions became iFGFR1-independent. Gene expression profiling at distinct stages of tumor progression revealed an increase in EMT-associated Sox9 and changes in the Wnt signaling pathway, including Fzd4, which was validated in human PCa. The iFGFR1 model clearly implicates FGFR1 in PCa progression and demonstrates how CID-inducible models can help evaluate candidate molecules in tumor progression and maintenance.