Tumor Microvessel Research Articles

DNA Thioaptamer with Homing Specificity to Lymphoma Bone Marrow Involvement.

Selective drug accumulation in the malignant tissue is a prerequisite for effective cancer treatment. However, most drug molecules and their formulated particles are blocked en route to the destiny tissue due to the existence of multiple biological and physical barriers including the tumor microvessel endothelium. Since the endothelial cells on the surface of the microvessel wall can be modulated by inflammatory cytokines and chemokines secreted by the tumor or stromal cells, an effective drug delivery approach is to enhance interaction between the drug particles and the unique spectrum of surface proteins on the tumor endothelium. In this study, we performed in vivo screening for thioaptamers that bind to the bone marrow endothelium with specificity in a murine model of lymphoma with bone marrow involvement (BMI). The R1 thioaptamer was isolated based on its high homing potency to bones with BMI, and 40-60% less efficiency in accumulation to healthy bones. In cell culture, R1 binds to human umbilical vein endothelial cells (HUVEC) with a high affinity ( Kd ≈ 3 nM), and the binding affinity can be further enhanced when cells were treated with a mixture of lymphoma cell and bone marrow cell conditioned media. Cellular uptake of R1 is through clathrin-mediated endocytosis. Conjugating R1 on to the surface of liposomal doxorubicin nanoparticles resulted in 2-3-fold increase in drug accumulation in lymphoma BMI. Taking together, we have successfully identified a thioaptamer that preferentially binds to the endothelium of lymphoma BMI. It can serve as an affinity moiety for targeted delivery of drug particles to the disease organ.

PDGFR-β inhibitor slows tumor growth but increases metastasis in combined radiotherapy and Endostar therapy

BackgroundPericytes are pivotal mural cells of blood vessels and play an essential role in coordinating the function of endothelial cells. Previous studies demonstrated that Endostar, a novel endostatin targeting endothelial cells, can enhance the effect of radiotherapy (RT). The present study addressed whether inhibiting pericytes could potentially improve the efficacy of combined RT and Endostar therapy. MethodsPlatelet-derived growth factor beta-receptor inhibitor (CP673451) was chosen to inhibit pericytes and RT (12 Gy) was delivered. Lewis lung carcinoma-bearing C57BL/6 mice were randomized into 3 groups: RT, RT + Endo, and RT + Endo + CP673451. Subsequently, tumor microvessel density (MVD), pericyte coverage, tumor hypoxia, and lung metastasis were monitored at different time points following different therapies. ResultsCompared to the other two groups, RT + Endo + CP673451 treatment markedly inhibited tumor growth with no improvement in the overall survival. Further analyses clarified that in comparison to RT alone, RT + Endo significantly reduced the tumor MVD, with a greater decrease noted in the RT + Endo + CP673451 group. However, additional CP673451 accentuated tumor hypoxia and enhanced the pulmonary metastasis in the combined RT and Endostar treatment. ConclusionsTumor growth can be further suppressed by pericyte inhibitor; however, metastases are potentially enhanced. More in-depth studies are warranted to confirm the potential benefits and risks of anti-pericyte therapy.

Early Contrast Enhancement: A novel magnetic resonance imaging biomarker of pleural malignancy

IntroductionPleural Malignancy (PM) is often occult on subjective radiological assessment. We sought to define a novel, semi-objective Magnetic Resonance Imaging (MRI) biomarker of PM, targeted to increased tumour microvessel density (MVD) and applicable to minimal pleural thickening. Materials and methods60 consecutive patients with suspected PM underwent contrast-enhanced 3-T MRI then pleural biopsy. In 58/60, parietal pleura signal intensity (SI) was measured in multiple regions of interest (ROI) at multiple time-points, generating ROI SI/time curves and Mean SI gradient (MSIG: SI increment/time). The diagnostic performance of Early Contrast Enhancement (ECE; which was defined as a SI peak in at least one ROI at or before 4.5 min) was compared with subjective MRI and Computed Tomography (CT) morphology results. MSIG was correlated against tumour MVD (based on Factor VIII immunostain) in 31 patients with Mesothelioma. Results71% (41/58) patients had PM. Pleural thickening was <10 mm in 49/58 (84%). ECE sensitivity was 83% (95% CI 61–94%), specificity 83% (95% CI 68–91%), positive predictive value 68% (95% CI 47–84%), negative predictive value 92% (78–97%). ECE performance was similar or superior to subjective CT and MRI. MSIG correlated with MVD (r = 0.4258, p = .02). DiscussionECE is a semi-objective, perfusion-based biomarker of PM, measurable in minimal pleural thickening. Further studies are warranted.

Repeated photon and C-ion irradiations in vivo have different impact on alteration of tumor characteristics

Precise characterization of tumor recurrence and regrowth after radiotherapy are important for prognostic understanding of the therapeutic effect. Here, we established a novel in vivo mouse model for evaluating the characteristics of regrown tumor after repeated photon and carbon ion (C-ion) irradiations. The results showed that tumor growth rate, lung metastasis, shortening of the survival of the tumor-bearing mice, and tumor microvessel formation were promoted 2- to 3-fold, and expression of angiogenic and metastatic genes increased 1.5- to 15-fold in regrown tumors after repeated photon irradiations, whereas repeated C-ion irradiations did not alter these characteristics. Interestingly, both repeated photon and C-ion irradiations did not generate radioresistance, which is generally acquired for in vitro treatment. Our results demonstrated that the repetition of photon, and not C-ion, irradiations in vivo alter the characteristics of the regrown tumor, making it more aggressive without acquisition of radioresistance.

Advanced gastric cancer reproducibility of region of interests in spectral CT imaging and their relationship with micro-vessel density

Objective To determine the consistency of spectral CT parameters in advanced gastric cancer using different region of interests (ROIs) and their relationship with tumor micro-vessel density (MVD). Methods Thirty patients with histologically proven gastric cancer were prospectively enrolled. All the patients were examined using spectral-dual-phase-abdominal CT and treated successfully with radical surgery within 2 weeks after CT scanning. Two observers independently acquired iodine concentration (IC), normalized IC (nIC), and CT value at workstation using three different ROI protocols: 10 mm2 circular ROI near tumor border where enhanced obviously, 30 mm2 near the tumor center and the freehand outline ROI. The Data of the two observers were tested with interclass correlation coefficient (ICC) and Bland-Altman plot. The mean value of each parameter was documented as the final result. Differences of each group of ROI data were compared using ANOVA test. All the specimen were pathologically examined and MVD was counted. The relationship of each parameter to tumor MVD was analyzed by Pearson correlation. Results All of the IC, nIC and CT values obtained by the 2 observers using three ROI measurements were consistent well, and the ROI-outline had the highest ICC than that of smaller circular ROIs (ICC: 0.991 to 0.997). The 95% differences confident interval of nIC-AP and nIC-VP using freehand outline ROI by two observers were -0.003 to 0.002 and-0.001 to 0.012, respectively. The outline-ROI method had better inter-observer accuracy. There were significant differences between the means of the all parameters with three ROI protocols (P<0.05). Values of ROI-10 mm2 were highest, while the values of ROI-outline were lowest (P<0.05). The mean counts of tumor MVD was (29.0±8.4)/high magnification. The nIC in venous phase (VP) had good correlations with intra-tumoral MVD, especially the ROI-outline (r=0.670, P<0.01), within different ROI measurements. Conclusions The different ROI selection in tumor has significant impact on the final CT parameters. Outlined ROI protocol improves inter-observer consistency and nIC-VP obtained by this method can indirectly reflect the condition of tumor angiogenesis. Key words: Stomach neoplasms; Tomography,X-ray computed; Comparative study; Region of interest

Challenges and opportunities of using stereotactic body radiotherapy with anti-angiogenesis agents in tumor therapy.

Microvessels promote proliferation of tumor cells by delivering oxygen and nutrients, but rapid growth of tumors results in unmet demands for oxygen and nutrients, thereby creating a hypoxia microenvironment. Under hypoxic conditions, vascular endothelial cells (ECs) initiate the formation of immature and abnormal microvasculature. This results in leakage and tortuosity that facilitates tumor cell invasion, metastasis and resistance to cytotoxic treatment. Radiotherapy (RT) is a vital tumor treatment modality. Currently, more than 60% of patients with malignant tumors receive RT at certain points during their treatment. Hypoxia induced by abnormal microvessels can hamper the cytotoxic effect of ionizing radiation, particularly, stereotactic body radiotherapy (SBRT). Anti-angiogenesis (AA) agents are known to reduce and renormalize microvessels in tumors, and hence alleviate hypoxia. The combination of AA agents with SBRT may have a synergistic role in inhibiting the growth of tumors. On the contrary, large doses of irradiation may affect tumor microvessels itself. In this review, we aim to clarify the relationship between SBRT and microvessel formation in tumors. In addition, we provide a retrospective analysis of the combination therapy involving SBRT and AA agents in preclinical and clinical practice to define its role in anti-tumor treatment.

HIF-1α expression is inversely associated with tumor stage, grade and microvessel density in urothelial bladder carcinoma.

Urothelial bladder carcinoma (UBC) is the most common urinary tract malignancy. The most important histopathological factors affecting prognosis are cancer stage and grade. Studies show that microvessel density (MVD) reflecting angiogenesis is also associated with clinicopathological features and affects the outcome in UBC. One of the most important regulators of angiogenesis is hypoxia inducible factor 1 (HIF-1). Previous reports describing expression of the HIF-1α subunit in UBC showed unclear and inconsistent results. Our study attempted do evaluate the association between HIF-1α expression and tumor stage, grade, lymph nodes status and MVD in UBC. We performed immunohistochemical staining in 99 UBC cases, including 38 non-muscle invasive (NMIBC) and 61 muscle invasive tumors (MIBC). We observed inverse relationships between HIF-1α immunoreactivity score (IRS) and tumor stage, grade and MVD. Significantly lower HIF-1α IRS values were observed in MIBC and high grade cancers. We found a significant negative correlation between HIF-1α IRS and MVD. These results suggest that HIF-1α pathway is not involved in UBC growth and progression, and that angiogenesis in high grade MIBC is not regulated by HIF-1. Our findings contradict previous reports regarding HIF-1α, MVD and UBC which shows the necessity of additional molecular studies in this field.

The Expression and Functional Significance of Vascular Endothelial-Cadherin, CD44, and Vimentin in Oral Squamous Cell Carcinoma.

Objectives:Ninety percent of head and neck cancers are squamous cell carcinoma which develops in the oral cavity. Metastasis is the main causative factor for death in 90% of all cancer-related deaths and begins with the invasion of tumor cells through the walls of small blood vessels or lymph vessels. A growing body of evidence has shown that vasculogenic mimicry (VM) facilitates tumor growth and cancer metastasis. The current study aimed to present the role of vascular endothelial (VE)-cadherin, CD44, and vimentin in inducing VM and epithelial-mesenchymal transition (EMT) and to identify the cancer stem cell (CSC) niche in different grades of oral squamous cell carcinoma (OSCC).Materials and Methods:A total of 63 OSCC samples (21 samples each grade) were collected from the archive of Pathology Department of Besat educational hospital, Hamadan, Iran, from 2000 to 2015. VE-cadherin, CD44, and vimentin/periodic acid–Schiff (PAS) double-staining were used to validate VM. VM was identified by the detection of PAS-positive loops surrounded by tumor cells. Chi-square test was used to examine the differences between the variables. Significant level was set at 0.05. Pearson's correlation was used to assess the co-localization of the markers.Results:There were statistically significant differences between tumor grade and the expression levels of VE-cadherin, CD44, and vimentin (P = 0.000). In addition, significant differences were found between tumor grade and microvessel density (P = 0.000) and between tumor grade and VM (P = 0.000).Conclusion:Our results may disclose a definite relationship between VE-cadherin, CD44 and vimentin expression levels, VM formation, EMT, CSCs, and microvessel count in OSCC samples. For this reason, it is suggested that VE-cadherin, CD44, and vimentin are related to angiogenesis and VM formation in OSCC, therefore, in tumor progression and metastasis. Recently, antitumor angiogenic therapies have been challenged. The presence of VM may explain the failure of antiangiogenic treatments.

Prognostic value of endoglin-assessed microvessel density in cancer patients: a systematic review and meta-analysis.

BackgroundEndoglin (ENG, CD105), an auxiliary receptor for several TGF-β superfamily ligands, is constitutively expressed in tumor microvessels. The prognostic value of ENG-assessed microvessel density (MVD) has not been systemically analyzed. This meta-analysis reviews and evaluates the association between ENG expression and prognosis in cancer patients.Materials and MethodsThirty published studies involving in 3613 patients were included after searching of PubMed, Web of Science, and EMBASE. The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) for overall survival (OS), disease-free survival (DFS), and cancer-specific survival (CSS) were calculated using random-effects models. The publication bias was detected by a Begg’s test and Egger’s test. The outcome stability was verified by sensitivity analysis.ResultsThe high ENG-assessed MVD was significantly associated with poor OS (HR = 2.14, 95% CI 1.62–2.81; P < 0.001), DFS (HR = 3.23, 95% CI 2.10–4.95; P < 0.001), CSS (HR = 3.33, 95% CI 1.32–8.37; P < 0.001). Furthermore, subgroup analysis revealed that the association between the overexpression of ENG in tumor microvessels and the outcome endpoints (OS or DFS) were also significant in the Asians and Caucasians patients with different cancer types.ConclusionsENG of tumor microvessels is a predictor of poor OS, DFS and CSS and may be a prognostic marker of patients with cancer.

The use of 5-fluorouracil-loaded nanobubbles combined with low-frequency ultrasound to treat hepatocellular carcinoma in nude mice

ObjectiveThis study aimed to investigate the therapeutic effects of 5-fluorouracil (5-FU)-loaded nanobubbles irradiated with low-intensity, low-frequency ultrasound in nude mice with hepatocellular carcinoma (HCC).MethodsA transplanted tumor model of HCC in nude mice was established in 40 mice, which were then randomly divided equally into four groups: group A (saline), group B (5-FU-loaded nanobubbles), group C (5-FU-loaded nanobubbles with non-low-frequency ultrasound), and group D (5-FU-loaded nanobubbles with low-frequency ultrasound). The tumor size in each mouse was observed via ultrasound before and after the treatments. Inhibition of the tumor growth in each group was compared, and survival curves were generated. Tumor tissues were removed to determine the apoptotic index using the TUNEL method and quantitative analysis. Tumor tissues with CD34-positive microvessels were observed by immunohistochemistry, and the tumor microvessel densities were calculated.ResultsThe growth rate of the tumor volumes in group D was significantly slower than that in the other groups, while the tumor inhibition rates and apoptotic index in group D were significantly higher than those of the other groups. The number of microvessels staining positive for CD34 was decreased in group D. Therefore, group D presented the most significant inhibitory effects.ConclusionsTherefore, 5-FU-loaded nanobubbles subjected to irradiation with low-frequency ultrasound could further improve drug targeting and effectively inhibit the growth of transplanted tumors, which is expected to become an ideal drug carrier and targeted drug delivery system for the treatment of HCC in the future.

Mitosis-Mediated Intravasation in a Tissue-Engineered Tumor-Microvessel Platform.

Intravasation involves the migration of tumor cells across the local endothelium and escape into vessel flow. Although tumor cell invasiveness has been correlated to increased intravasation, the details of transendothelial migration and detachment into circulation are still unclear. Here, we analyzed the intravasation of invasive human breast cancer cells within a tissue-engineered microvessel model of the tumor microenvironment. Using live-cell fluorescence microscopy, we captured 2,330 hours of tumor cell interactions with functional microvessels and provide evidence for a mitosis-mediated mechanism where tumor cells located along the vessel periphery are able to disrupt the vessel endothelium through cell division and detach into circulation. This model provides a framework for understanding the physical and biological parameters of the tumor microenvironment that mediate intravasation of tumor cells across an intact endothelium. Cancer Res; 77(22); 6453-61. ©2017 AACR.

TMIC-41. LOSS OF HOST-DERIVED OSTEOPONTIN CREATES A GLIOBLASTOMA-PROMOTING MICROENVIRONMENT

Microglia and periphery-derived monocytes infiltrate human and mouse glioblastoma and their density is positively correlated with malignancy. Using microarray and RNA sequencing we have previously shown that glioblastoma-associated microglia/monocytes (GAMs) express osteopontin/OPN. We used qRT-PCR, immunofluorescence stainings, western blot, and flow cytometry to identify the various sources of OPN expression in human and mouse glioblastoma. We implanted wild type GL261 glioblastoma cells, which do not express significant levels of OPN, into wild-type and OPN-/- mice to investigate the role of microenvironment-derived OPN on glioblastoma progression. Our data indicates that GAMs are the predominant source of OPN in both human and mouse glioblastoma and only express the secreted form of OPN. Loss of microenvironment-derived OPN enhanced tumor progression. Ki67 and TUNEL staining showed no difference in overall cell proliferation but a decreased apoptosis rate in tumors in OPN-/- mice. CD31 staining showed a significantly decreased number of microvessels in tumors in OPN-/- mice, accompanied by reduced coverage of vessels with PDGFRβ-positive pericytes. Flow cytometry analysis revealed a significant increase of CD11b+/CD45low microglia but not of CD11b+/CD45high macrophages/monocytes in tumors in OPN-/- mice. Sorted CD11b+ cells from wild type and OPN-/- naïve brains and tumors did not show a significant difference in the expression pattern of activation marker genes. Our results show that in human and mouse glioblastoma OPN is predominantly expressed and secreted by GAMs and that – in contrast to OPN expression in the tumor cells per se – loss of stroma-derived OPN creates a glioblastoma-promoting microenvironment.

The dual effects of a novel peptibody on angiogenesis inhibition and M2 macrophage polarization on sarcoma

Inhibition of the VEGF/VEGF receptor (VEGFR) and angiopoietin-2 (Ang-2)/TEK receptor tyrosine kinase (Tie-2) pathway is a potential target for tumor angiogenesis. We previously showed that a peptide AS16 which dually inhibits VEGFR/Ang-2 could reduce the tumor growth and decrease the number of microvessels in tumor. However, its short circulating half-life in the serum limits its clinical applications. In this study, as an effort to prolong the short in vivo half-life of AS16, we designed a fusion protein containing peptide AS16 and an IgG Fc fragment. Pharmacokinetic study also revealed that AS16-Fc has a prolonged circulating half-life of about 231 min in rats. We examined the effects of treatment on the tumor vasculature and immune cell populations, tumor growth, in both the MCA-205 and S180 tumor models. We found that AS16-Fc dramatically reduced tumor volume, vascular density and tumor-associated macrophages. Macrophages were identified as potential novel targets following anti-angiogenic therapy, our findings imply a novel role for anti-angiogenic peptide AS16-Fc. These findings indicate that AS16-Fc could be more effective on inhibiting tumor growth angiogenesis and tumor immune microenvironment than that of peptide AS16.

Aberrant glioblastoma neovascularization patterns and their correlation with DCE-MRI-derived parameters following temozolomide and bevacizumab treatment

Glioblastoma (GBM) is a highly angiogenic malignancy, and its abundant, aberrant neovascularization is closely related to the proliferation and invasion of tumor cells. However, anti-angiogenesis combined with standard radio-/chemo-therapy produces little improvement in treatment outcomes. Determining the reason for treatment failure is pivotal for GBM treatment. Here, histopathological analysis and dynamic contrast-enhanced MRI (DCE-MRI) were used to explore the effects of temozolomide (TMZ) and bevacizumab (BEV) on GBM neovascularization patterns in an orthotopic U87MG mouse model at 1, 3 and 6 days after treatment. We found that the amount of vascular mimicry (VM) significantly increased 6 days after BEV treatment. TMZ inhibited neovascularization at an early stage, but the microvessel density (MVD) and transfer coefficient (Ktrans) derived from DCE-MRI increased 6 days after treatment. TMZ and BEV combination therapy slightly prolonged the inhibitory effect on tumor microvessels. Sprouting angiogenesis was positively correlated with Ktrans in all treatment groups. The increase in VM after BEV administration and the increase in MVD and Ktrans after TMZ administration may be responsible for treatment resistance. Ktrans holds great potential as an imaging biomarker for indicating the variation in sprouting angiogenesis during drug treatment for GBM.

Antiangiogenic effects of recombinant human endostatin in lung cancers.

Antiangiogenic therapy, as a new anticancer method, can improve the anticancer effect of traditional therapies. Different antiangiogenic drugs may have different vascular normalization time windows. Whether the antiangiogenic treatment is within the vascular normalization time window is very important in the treatment of cancers. Previous studies have indicated that recombinant human endostatin (rh-ES) can transiently normalize tumor microvessels. Yet the molecular mechanism and the time window of rh-ES remains unclear. The aim of the present study was to explore the optimal time window and molecular mechanism of rh-ES in inhibiting Lewis lung cancer (LLC). By comparatively accessing the changes in microvascular and hypoxic conditions of tumors in host mice treated with rh-ES or saline for different days, the authors aimed to investigate the best administration time of rh-ES treatment on human lung cancers and obtain a better understanding concerning the involved molecular mechanism. A total of 40 C57/BL6 mice with LLC xenografts were randomly divided into normal saline (NS) and rh-ES groups (20 mice/group). 0.2 ml NS or 5 mg/kg rh-ES were administrated via intraperitoneal injection (i.p.) into each mouse each day during the 9-day experiment. A total of 5 mice from each group were sacrificed at day 2, 4, 6 or 9. CA9 and RGS5 expression levels of both groups were compared using immunohistochemistry, reverse transcription-quantitative polymerase chain reaction and ELISA. Rh-ES caused vascular normalization and improved hypoxia at days 4 and 6. Compared with the control (NS) group, both CA9 and RGS5 expression in rh-ES group were significantly decreased at days 4 and 6 (P<0.05), while no significant change between two groups was observed at days 2 and 9. Rh-ES can induce transient tumor vascular normalization and improves tissue hypoxia in LLC tumors. The vascular normalization window is accompanied by the reduction in RGS5 and CA expression.

Single-walled carbon nanotube: One specific inhibitor of cancer stem cells in osteosarcoma upon downregulation of the TGFβ1 signaling

Cancer stem cells (CSCs) are believed to have a critical role in tumorigenesis, metastasis, therapeutic resistance or recurrence. Therefore, strategies designed to specifically target and eliminate CSCs have become one of the most promising and desirable ways for tumor treatment. Osteosarcoma stem cells (OSCs), the CSCs in osteosarcoma (OS), are critically associated with OS progression. Here, we show that single-walled carbon nanotubes (SWCNTs), including unmodified SWCNT (SWCNT-Raw) and SWCNT-COOH, have the ability to specifically inhibit the process of TGFβ1-induced OS cells dedifferentiation, prevent the stem cell phenotypes acquisition in OS cells and reduce the OSC viability under conditions which mimic the OS microenvironment. Concurrently, SWCNT treatment significantly down-regulates the expression of OSC markers in OS, and markedly reduces the tumor microvessel density and tumor growth. Furthermore, we found that SWCNT could suppress the TGFβ1-induced activation of TGFβ type I receptor and downstream signaling, which are key for the OSC formation and maintenance. Our results reveal an unexpected function of SWCNT in negative modulation of OSCs, and provide significant implications for the potential CSCs-targeted therapeutic applications of SWCNT.

The experimental research of hypoxia-inducible factor-1α small interfering RNA on the growth of human bladder cancer xenografts in mice

Objective To observe the inhibitory effect of hypoxia inducible factor -1α(HIF-1α) siRNA on the growth of human bladder cancer xenografts in mice, and to explore the effectiveness of HIF-1α as a target for bladder cancer gene therapy. Methods pGC-siHIF-1α of stably transfected into human bladder cancer cell line T24 was inoculated to mice bladder, and the mouse model of bladder cancer was established .The tumor growth was observed by CT, and the level of tumor cells HIF-1α and CD34 was detected by immunohistochemistry (SABC), and the expression of tumor microvessel density (MVD) was evaluated according to the expression of CD34. The apoptosis index of tumor cells was determined by terminal transferase labeling (TUNEL). Results Comparison between experimental group and control group, compose got the lower rate experiment, slow tumor growth (P<0.05). HIF-1α levels decreased (P<0.01), tumor microvessel density decreased (P<0.01), and the apoptosis index was significantly increased (P<0.01). Compared with the control group, the differences between the two groups were statistically significant. Conclusions As the target of HIF-1α, the siRNA have inhibited HIF-1αexpression, contain T24 bladder cancer cells in vivo. HIF-1α may become a potential target for clinical gene therapy for bladder cancer, and provide experimental basis for anti-angiogenesis therapy of bladder cancer. Key words: Urinary Bladder Neoplasms; RNA, Small Interfering; Hypoxia-Inducible Factor 1, alpha Subunit; Mice

Normalizing Tumor Vessels To Increase the Enzyme-Induced Retention and Targeting of Gold Nanoparticle for Breast Cancer Imaging and Treatment.

Abnormal tumor vessels impede the transport and distribution of chemotherapeutics, resulting in low drug concentration at tumor sites and compromised drug efficacy. Normalizing tumor vessels can modulate tumor vascular permeability, alleviate tumor hypoxia, increase blood perfusion, attenuate interstitial fluid pressure, and improve drug delivery. Herein, a novel strategy combining cediranib, a tumor vessel normalizing agent, with an enzyme responsive size-changeable gold nanoparticle (AuNPs-A&C) was developed. In vivo photoacoustic and fluorescence imaging showed that oral pretreatment with 6 mg/kg/day of cediranib for two consecutive days significantly enhanced the retention of AuNPs-A&C in 4T1 tumor. In vivo photoacoustic imaging for hemoglobin (Hb) and oxyhemoglobin (HbO2), Evans blue assay, and immunofluorescence assay showed that cediranib pretreatment markedly increased tumor vascular permeability and tumor oxygenation, while distinctly decreased the tumor microvessel density, demonstrating normalized tumor vessels and favorably altered microenvironment. Additionally, the combination strategy considerably elevated the tumor targeting capacity of different nanoparticle formulations (AuNPs-PEG, AuNPs-A&C), while coadministration of cediranib and AuNPs-A&C achieved prevailing tumor targeting and antitumor efficacy in 4T1 tumor bearing mouse model. In conclusion, we report a novel combined administration strategy to further improve tumor diagnosis and treatment.

Loss of host-derived osteopontin creates a glioblastoma-promoting microenvironment.

Microglia and periphery-derived monocytes infiltrate human and mouse glioblastoma and their density is positively correlated with malignancy. Using microarray and RNA sequencing, we have previously shown that glioblastoma-associated microglia/monocytes (GAMs) express osteopontin/SPP1. We used quantitative reverse transcriptase PCR, immunofluorescence stainings, western blot, and flow cytometry to identify the various sources of osteopontin (OPN) expression in human and mouse glioblastoma. We implanted wild type GL261 glioblastoma cells, which do not express significant levels of OPN, into wild type and OPN-/- mice to investigate the role of microenvironment-derived OPN on glioblastoma progression. Our data indicate that GAMs are the predominant source of OPN in both human and mouse glioblastoma and express only the secreted form of OPN. Loss of microenvironment-derived OPN enhanced tumor progression. Staining by Ki67 and terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling showed no difference in overall cell proliferation but a decreased apoptosis rate in tumors in OPN-/- mice. CD31 staining showed a significantly decreased number of microvessels in tumors in OPN-/- mice, accompanied by reduced coverage of vessels with platelet derived growth factor receptor β+ pericytes. Flow cytometry analysis revealed a significant increase of CD11b+/CD45low microglia but not of CD11b+/CD45high macrophages/monocytes in tumors in OPN-/- mice. Sorted CD11b+ cells from wild type and OPN-/- naïve brains and tumors did not show a significant difference in the expression pattern of activation marker genes. Our results show that in tested human and mouse glioblastoma samples, OPN is predominantly expressed and secreted by GAMs and that, in contrast to OPN expression in the tumor cells per se, loss of stroma-derived OPN creates a glioblastoma-promoting microenvironment.

Combination therapy using molecular-targeted drugs modulates tumor microenvironment and impairs tumor growth in renal cell carcinoma.

Tumor growth and metastasis are determined not by cancer cells alone but also by a variety of stromal cells, various populations of which overexpress platelet‐derived growth factor receptors (PDGF‐Rs). In addition, activation of PI3K‐AKT‐mammalian target of rapamycin (mTOR) signaling is frequently observed in many cancer types as well. mTOR comprises a serine/threonine kinase that increases the production of proteins that stimulate key cellular processes such as cell growth and proliferation, cell metabolism, and angiogenesis. In this study, we investigated the impact of molecular‐targeting agents including PDGF‐R and mTOR inhibitors on the tumor stroma of human kidney cancer and examined the efficacy of combination therapy with these agents against this disease. Treatment with sunitinib did not suppress tumor growth, but significantly decreased stromal reactivity, microvessel density, and pericyte coverage of tumor microvessels in an orthotopic mouse model. In contrast, treatment with everolimus decreased tumor growth and microvessel density but not stromal reactivity. However, sunitinib and everolimus in combination reduced both the growth rate and stromal reaction. These findings suggest that target molecule‐based inhibition of the cancer–stromal cell interaction appears promising as an effective antitumor therapy.