A Flexible Semi-automated Assay for Assessing Radiation-sensitization and Toxicity in the Mouse Intestine.

Background/aim: The aim of this study was to develop an enhanced intestinal toxicity assay with three outputs assessing proliferation, villi morphology and DNA damage after irradiation.

Materials And Methods: Whole 5 cm jejunal lengths were collected from mice following total body x-ray irradiation (0-15 Gy) at 0-84 h. Tissues were wrapped into swirls for cryopreservation and immunohistochemically stained for EdU, CD31, and γH2AX.

Radiation and Chemo-Sensitizing Effects of DNA-PK Inhibitors Are Proportional in Tumors and Normal Tissues.

Inhibitors of DNA-dependent protein kinase (PRKDC; DNA-PK) sensitize cancers to radiotherapy and DNA-damaging chemotherapies, with candidates in clinical trials. However, the degree to which DNA-PK inhibitors also sensitize normal tissues remains poorly characterized. In this study, we compare tumor growth control and normal tissue sensitization following DNA-PK inhibitors in combination with radiation and etoposide.

DNA-PK inhibitor AZD7648 is a more portent radiosensitizer than PARP inhibitor Olaparib in BRCA1/2 deficient tumors.

The effectiveness of radiotherapy depends on the sensitivities of 'normal' and cancer cells to the administered radiation dose. Increasing the radiosensitivity of cancers by inhibiting DNA damage repair is a goal of much current research, however success depends on avoiding concomitant sensitization of normal tissues inevitably irradiated during therapy. In this study we investigated the mechanisms of radiosensitization for DNA-PK and PARP inhibitors by examining the impacts on proliferating vs quiescent cell populations.

DNA-PK inhibition extends the therapeutic effects of Top2 poisoning to non-proliferating cells, increasing activity at a cost.

Type II topoisomerase (Top2) poisoning therapy is used to treat a broad range of cancers via induction of double strand breaks (DSBs) in cells undergoing replication and transcription. Preventing the repair of DSBs via inhibition of DNA-PK, an inhibitor of non-homologous end-joining (NHEJ), increases cell kill with Top2 poisons and has led to the initiation of several clinical trials. To elucidate the cellular mechanisms leading to synergistic activity of dual DNA-PK/Top2 inhibition we looked at their effects in cycling versus non-cycling cells, in 3D spheroids and in xenograft models.

Radiosensitizing oxygenation changes in murine tumors treated with VEGF-ablation therapy are measurable using oxygen enhanced-MRI (OE-MRI).

Purpose: There is a significant need for a widely available, translatable, sensitive and non-invasive imaging biomarker for tumor hypoxia in radiation oncology. Treatment-induced changes in tumor tissue oxygenation can alter the sensitivity of cancer tissues to radiation, but the relative difficulty in monitoring the tumor microenvironment results in scarce clinical and research data. Oxygen-Enhanced MRI (OE-MRI) uses inhaled oxygen as a contrast agent to measure tissue oxygenation.

Targeting Hypoxia-Induced Carbonic Anhydrase IX Enhances Immune-Checkpoint Blockade Locally and Systemically.

Treatment strategies involving immune-checkpoint blockade (ICB) have significantly improved survival for a subset of patients across a broad spectrum of advanced solid cancers. Despite this, considerable room for improving response rates remains. The tumor microenvironment (TME) is a hurdle to immune function, as the altered metabolism-related acidic microenvironment of solid tumors decreases immune activity.

Fast and sensitive dynamic oxygen-enhanced MRI with a cycling gas challenge and independent component analysis.

Purpose: There is a critical need for non-invasive imaging biomarkers of tumor oxygenation to assist in patient stratification and development of hypoxia targeting therapies. Using a cycling gas challenge and independent component analysis (ICA), we sought to improve the sensitivity and speed of existing oxygen enhanced MRI (OE-MRI) techniques to detect changes in oxygenation with dynamically acquired T W signal intensity images (dOE-MRI).

Methods: Mice were implanted with SCCVII, HCT-116, BT-474, or SKOV3 tumors in the dorsal subcutaneous region and imaged at 7T.

Heterogeneous distribution of trastuzumab in HER2-positive xenografts and metastases: role of the tumor microenvironment.

Most HER2-positive metastatic breast cancer patients continue to relapse. Incomplete access to all target HER2-positive cells in metastases and tumor tissues is a potential mechanism of resistance to trastuzumab. The location of locally bound trastuzumab was evaluated in HER2-positive tissues in vivo and as in vivo xenografts or metastases models in mice.

Multi-modal magnetic resonance imaging and histology of vascular function in xenografts using macromolecular contrast agent hyperbranched polyglycerol (HPG-GdF).

Macromolecular gadolinium (Gd)-based contrast agents are in development as blood pool markers for MRI. HPG-GdF is a 583 kDa hyperbranched polyglycerol doubly tagged with Gd and Alexa 647 nm dye, making it both MR and histologically visible. In this study we examined the location of HPG-GdF in whole-tumor xenograft sections matched to in vivo DCE-MR images of both HPG-GdF and Gadovist.

Loss of the Notch effector RBPJ promotes tumorigenesis.

Aberrant Notch activity is oncogenic in several malignancies, but it is unclear how expression or function of downstream elements in the Notch pathway affects tumor growth. Transcriptional regulation by Notch is dependent on interaction with the DNA-binding transcriptional repressor, RBPJ, and consequent derepression or activation of associated gene promoters. We show here that RBPJ is frequently depleted in human tumors.

Endothelial-specific Notch blockade inhibits vascular function and tumor growth through an eNOS-dependent mechanism.

Notch signaling is important for tumor angiogenesis induced by vascular endothelial growth factor A. Blockade of the Notch ligand Dll4 inhibits tumor growth in a paradoxical way. Dll4 inhibition increases endothelial cell sprouting, but vessels show reduced perfusion.

Hyperbranched polyglycerols as trimodal imaging agents: design, biocompatibility, and tumor uptake.

Combining various imaging modalities often leads to complementary information and synergistic advantages. A trimodal long-circulating imaging agent tagged with radioactive, magnetic resonance, and fluorescence markers is able to combine the high sensitivity of SPECT with the high resolution of MRI over hours and days. The fluorescence marker helps to confirm the in vivo imaging information at the microscopic level, in the context of the tumor microenvironment.

Targeting quiescent tumor cells via oxygen and IGF-I supplementation.

Conventional chemotherapy targets proliferating cancer cells, but most cells in solid tumors are not in a proliferative state. Thus, strategies to enable conventional chemotherapy to target noncycling cells may greatly increase tumor responsiveness. In this study, we used a 3-dimensional tissue culture system to assay diffusible factors that can limit proliferation in the context of the tumor microenvironment, with the goal of identifying targets to heighten proliferative capacity in this setting.

Tissue uptake of docetaxel loaded hydrophobically derivatized hyperbranched polyglycerols and their effects on the morphology of the bladder urothelium.

Recently, we have reported that docetaxel (DTX) loaded, amine terminated hyperbranched polyglycerol (HPG-C(8/10)-MePEG-NH(2)) nanoparticles significantly increased drug uptake in mouse bladder tissues and was the most effective formulation to significantly inhibit tumor growth in an orthotopic model of bladder cancer. The objective of this study was to investigate the effects of HPG-C(8/10)-MePEG-NH(2) nanoparticles on bladder urothelial morphology and integrity, DTX uptake and permeability in bladder tissue and the extent of bladder urothelial recovery following exposure to, and then washout of, HPG-C(8/10)-MePEG-NH(2) nanoparticles. HPG-C(8/10)-MePEG-NH(2) nanoparticles significantly increased the uptake of DTX in both isolated pig bladder as well as in live mouse bladder tissues.

The combination of gefitinib and RAD001 inhibits growth of HER2 overexpressing breast cancer cells and tumors irrespective of trastuzumab sensitivity.

Background: HER2-positive breast cancers exhibit high rates of innate and acquired resistance to trastuzumab (TZ), a HER2-directed antibody used as a first line treatment for this disease. TZ resistance may in part be mediated by frequent co-expression of EGFR and by sustained activation of the mammalian target of rapamycin (mTOR) pathway. Here, we assessed feasibility of combining the EGFR inhibitor gefitinib and the mTOR inhibitor everolimus (RAD001) for treating HER2 overexpressing breast cancers with different sensitivity to TZ.

In vivo evaluation of mucoadhesive nanoparticulate docetaxel for intravesical treatment of non-muscle-invasive bladder cancer.

Purpose: The present work describes the development and in vitro and in vivo evaluation of a mucoadhesive nanoparticulate docetaxel (DTX) formulation for intravesical bladder cancer therapy.

Experimental Design: Mucoadhesive formulations based on hyperbranched polyglycerols (HPG), hydrophobically derivatized with C(8)/C(10) alkyl chains in the core and modified with methoxy-polyethylene glycol (MePEG) and amine groups in the shell (HPG-C(8/10)-MePEG-NH(2)) were synthesized and DTX was loaded into these by a solvent evaporation method. Both low-grade (RT4, MGHU3) and high-grade (UMUC3) human urothelial carcinoma cell lines were treated with various concentrations of DTX formulations in vitro.

Detecting vascular-targeting effects of the hypoxic cytotoxin tirapazamine in tumor xenografts using magnetic resonance imaging.

Purpose: To determine whether vascular-targeting effects can be detected in vivo using magnetic resonance imaging (MRI).

Methods And Materials: MR images of HCT-116 xenograft-bearing mice were acquired at 7 Tesla before and 24 hours after intraperitoneal injections of tirapazamine. Quantitative dynamic contrast-enhanced MRI analyses were performed to evaluate changes in tumor perfusion using two biomarkers: the volume transfer constant (K(trans)) and the initial area under the concentration-time curve (IAUC).

Irinophore C, a novel nanoformulation of irinotecan, alters tumor vascular function and enhances the distribution of 5-fluorouracil and doxorubicin.

Purpose: To examine the antitumor effects of Irinophore C, a nanopharmaceutical formulation of irinotecan, on the tissue morphology and function of tumor vasculature in HT-29 human colorectal tumors.

Experimental Design: Fluorescence microscopy was used to map and quantify changes in tissue density, tumor vasculature, hypoxia, and the distribution of Hoechst 33342, a perfusion marker, and the anticancer drug, doxorubicin. Noninvasive magnetic resonance imaging was used to quantify Ktrans, the volume transfer constant of a solute between the blood vessels and extracellular tissue compartment of the tumor, as a measure of vascular function.

Vascular-specific quantification in an in vivo Matrigel chamber angiogenesis assay.

The study of angiogenesis as a therapeutic target requires reliable in vivo assays that can provide physiologically relevant data. A murine in vivo Matrigel-based angiogenesis assay is presented here which includes the quantitative assessment of vascular-specific indicators of neovascularization. Matrigel containing 175 ng/ml bFGF is encapsulated in synthetic chambers which are implanted subcutaneously in C57/B16J mice.