Irradiated Tumor-bearing Mice Research Articles

Molecular Imaging Investigations of Polymer-Coated Cerium Oxide Nanoparticles as a Radioprotective Therapeutic Candidate.

Cerium oxide nanoparticles (CONPs) have a unique surface redox chemistry that appears to selectively protect normal tissues from radiation induced damage. Our prior research exploring the biocompatibility of polymer-coated CONPs found further study of poly-acrylic acid (PAA)-coated CONPs was warranted due to improved systemic biodistribution and rapid renal clearance. This work further explores PAA-CONPs' radioprotective efficacy and mechanism of action related to tumor microenvironment pH. An ex vivo TUNEL assay was used to measure PAA-CONPs' protection of the irradiated mouse colon in comparison to the established radioprotector amifostine. [18F]FDG PET imaging of spontaneous colon tumors was utilized to determine the effects of PAA-CONPs on tumor radiation response. In vivo MRI and an ex vivo clonogenic assay were used to determine pH effects on PAA-CONPs' radioprotection in irradiated tumor-bearing mice. PAA-CONPs showed excellent radioprotective efficacy in the normal colon that was equivalent to uncoated CONPs and amifostine. [18F]FDG PET imaging showed PAA-CONPs do not affect tumor response to radiation. Normalization of tumor pH allowed some radioprotection of tumors by PAA-CONPs, which may explain their lack of tumor radioprotection in the acidic tumor microenvironment. Overall, PAA-CONPs meet the criteria for clinical application as a radioprotective therapeutic agent and are an excellent candidate for further study.

MiR-26b-5p in small extracellular vesicles derived from dying tumor cells after irradiation enhances the metastasis promoting microenvironment in esophageal squamous cell carcinoma

Radiation therapy is effective in achieving local control in esophageal squamous cell carcinoma; however, changes in the tumor microenvironment induced by radiation can also promote metastasis. Dying tumor cells play vital roles in promoting the survival of living tumor cells; however, few studies have investigated the effects of dying tumor cells on the tumor microenvironment. Since myeloid-derived suppressor cells (MDSCs) and macrophages constitute the pre-metastatic niche (PMN), we used a 4-nitroquinoline-1-oxide induced in situ tumor model to investigate the effects of irradiation on MDSCs and macrophages in esophageal squamous cell carcinoma (ESCC). When primary tumor sites were irradiated, we observed an increase in MDSCs in the spleen and the deposition of PMN components in lung and liver. Enhanced MDSC accumulation and function were induced by small extracellular vesicles (sEVs) isolated from irradiated tumor-bearing mice. The MDSC induction function of sEVs after irradiation was reaffirmed using sEVs derived from ESCC cell lines. The irradiation-induced upregulation of miR-26b-5p in sEVs enhanced MDSC expansion and activation by targeting phosphatase and tensin homolog. Our results first elucidated a mechanism by which dying tumor cells enhanced the deposition of PMN components and potentiated MDSCs in ESCC after irradiation. sEVs played a vital role in mediating signals between the primary tumor and the microenvironment to form a metastasis-promoting microenvironment after irradiation. Furthermore, miR-26b-5p or PI3K/AKT signaling pathway inhibitors should be evaluated in clinical trials in combination with radiotherapy as a strategy to improve outcomes.

The resveratrol analogue, HS‑1793, enhances the effects of radiation therapy through the induction of anti‑tumor immunity in mammary tumor growth.

Radiotherapy can induce the infiltration of immune suppressive cells which are involved in promoting tumor progression and recurrence. A number of natural products with immunomodulating abilities have been gaining attention as complementary cancer treatments. This attention is partly due to therapeutic strategies which have proven to be ineffective as a result of tumor-induced immunosuppressive cells found in the tumor microenvironment. The present study investigated whether HS-1793, a resveratrol analogue, can enhance the anti-tumor effects by inhibiting lymphocyte damage and immune suppression by regulatory T cells (Tregs) and tumor-associated macrophages (TAMs), during radiation therapy. FM3A cells were used to determine the role of HS-1793 in the radiation-induced tumor immunity of murine breast cancer. HS-1793 treatment with radiation significantly increased lymphocyte proliferation with concanavalin A (Con A) stimulation and reduced the DNA damage of lymphocytes in irradiated tumor-bearing mice. The administration of HS-1793 also decreased the number of Tregs, and reduced interleukin (IL)-10 and transforming growth factor (TGF)-β secretion in irradiated tumor-bearing mice. In addition, HS-1793 treatment inhibited CD206+ TAM infiltration in tumor tissue when compared to the controls or irradiation alone. Mechanistically, HS-1793 suppressed tumor growth via the activation of effector T cells in irradiated mice. On the whole, the findings of the present study reveal that HS-1793 treatment improves the outcome of radiation therapy by enhancing antitumor immunity. Indeed, HS-1793 appears to be a good therapeutic candidate for use in combination with radiotherapy in breast cancer.

Utilizing 808nm laser for sensitizing of melanoma tumors to megavoltage radiation therapy.

Melanotic melanoma has high content of melanin and laser can destroy melanin-containing cells through thermal effect. In this study, the therapeutic effect of 808nm laser therapy was investigated on B16-F10 melanoma tumor growth and tumor-bearing mice survival time. In addition, as laser can destroy melanin as the main cause of melanoma radioresistance, the effect of laser administration to enhance radiation therapy efficacy at B16-F10 cancer cells was evaluated in vitro and in vivo. Laser therapy (1W/cm2 × 4min) could cause significant (P < 0.05) inhibition of melanoma tumors' growth (~ 61%) and about three times increase of the tumor-bearing mice survival time in comparison with no-treatment group. In addition, the mice which were treated with 1W/cm2 × 4min laser administration plus 6Gy megavoltage radiation therapy exhibited ~ 68% lesser tumors' volume and 27days increase of survival time in comparison with 6Gy irradiated tumor-bearing mice. Also, significantly higher (P < 0.05) tumor necrosis percentage was observed at the histopathological slides of 1W/cm2 × 4min laser + RT treated mice tumors (57 ± 12%) in comparison with radiation therapy group (31 ± 10%). Therefore, not only laser therapy can inhibit melanoma tumors' growth per se but also its combination with radiation therapy can cause a significant enhancement of radiation therapy efficacy. The laser administration can be used as a radiosensitizing method for melanotic melanoma radiation therapy.

Abstract 847: Optimization of radiation regimen in a carcinogen-induced mouse model for lung cancer

Abstract Purpose: Lung cancer remains the most common cause of cancer-related mortality in United States and worldwide. The major cause of lung cancer is attributed to carcinogens present in tobacco smoke, air pollution, diet and food supplements, occupational and other environmental exposures. Lung Cancer Mutation Consortium has identified many recognized “driver mutations” in nearly two-thirds of the patients who developed advanced form of lung cancer. Our primary goal is to understand the mechanism underlying the variations in radiation sensitivity with driver mutations and optimize radiation dose and treatment regimen. A better understanding of the most frequent driving mutations is required for progression towards personalized therapy. Methods: Urethane, a carcinogen injected via intraperitoneal route into A/J mice induced multiple lung tumors by week 25 that resembled non-small cell lung carcinoma. These lung tumors were assessed via MRI and each tumor was longitudinally tracked via surface rendered 3D imaging following X-ray exposure using small animal radiation research platform (SARRP). We employed acute high single dose (12 Gy) and clinically relevant fractionated dose (3 X 5 Gy). Individual lung tumor was also dissected from non-irradiated and irradiated mice followed by collagenase digestion and then cultured in a specific media for in-vitro mutational analysis. Results: Urethane induced multiple lung tumors (20-25 tumors with 1mg/kg urethane) of varying size (0.5 - 2mm) were detectable by MRI at 25 week following injection. Longitudinal MRI performed on irradiated tumor bearing mice showed significant regression after radiation with commitment survival benefit. Mice performed better when exposed to fractionated regimen than high single dose with relatively low level radiation toxicity. Primary lung cancer cells were prepared from the explanted tumors for prospectively examining relevant driver mutations and studying the genetic determinants of resistance and to identify novel targets. We also have collected body fluids for investigating changes in molecular profile of exosomes at time points after irradiation. Conclusions: Our study thus far set up a platform for longitudinal 3D tracking of individual lung tumors following treatment and recurrence. Tumor regression was evident after a week of radiation exposure. Primary lung tumor cell cultures were successfully established for molecular analysis and mechanistic studies Citation Format: Sagar Bhayana, Joseph Liu, Arnab Chakravarti, Naduparambil K. Jacob. Optimization of radiation regimen in a carcinogen-induced mouse model for lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 847.

281 - PET imaging of the PD-1/PD-L1 checkpoint in naive and irradiated tumor-bearing mice

281 - PET imaging of the PD-1/PD-L1 checkpoint in naive and irradiated tumor-bearing mice

Positron Emission Tomography Imaging of the PD-1/PD-L1 Checkpoint in Naïve and Irradiated Tumor-Bearing Mice

Positron Emission Tomography Imaging of the PD-1/PD-L1 Checkpoint in Naïve and Irradiated Tumor-Bearing Mice

1057P - Noninvasive PET imaging of the PD-1/PD-L1 checkpoint in naïve and irradiated tumor-bearing mice

1057P - Noninvasive PET imaging of the PD-1/PD-L1 checkpoint in naïve and irradiated tumor-bearing mice

Radiation-induced lung fibrosis in a tumor-bearing mouse model is associated with enhanced Type-2 immunity.

Lung fibrosis may be associated with Type-2 polarized inflammation. Herein, we aim to investigate whether radiation can initiate a Type-2 immune response and contribute to the progression of pulmonary fibrosis in tumor-bearing animals. We developed a tumor-bearing mouse model with Lewis lung cancer to receive either radiation therapy alone or radiation combined with Th1 immunomodulator unmethylated cytosine-phosphorothioate-guanine containing oligodeoxynucleotide (CpG-ODN). The Type-2 immune phenotype in tumors and the histological grade of lung fibrosis were evaluated in mice sacrificed three weeks after irradiation. Mouse lung tissues were analyzed for hydroxyproline and the expression of Type-1/Type-2 key transcription factors (T-bet/GATA-3). The concentration of Type-1/Type-2 cytokines in serum was measured by cytometric bead array. Lung fibrosis was observed to be more serious in tumor-bearing mice than in normal mice post-irradiation. The fibrosis score in irradiated tumor-bearing mice on Day 21 was 4.33 ± 0.82, which was higher than that of normal mice (2.00 ± 0.63; P < 0.05). Hydroxyproline and GATA-3 expression were increased in the lung tissues of tumor-bearing mice following irradiation. CpG-ODN attenuated fibrosis by markedly decreasing GATA-3 expression. Serum IL-13 and IL-5 were elevated, whereas INF-γ and IL-12 expression were decreased in irradiated tumor-bearing mice. These changes were reversed after CpG-ODN treatment. Thus, Type-2 immunity in tumors appeared to affect the outcome of radiation damage and might be of interest for future studies on developing approaches in which Type-1–related immunotherapy and radiotherapy are used in combination.

The timing of surgery after neoadjuvant radiotherapy influences tumor dissemination in a preclinical model.

Neoadjuvant radiotherapy (neoRT) used in cancer treatments aims at improving local tumor control and patient overall survival. The neoRT schedule and the timing of the surgical treatment (ST) are empirically based and influenced by the clinician's experience. The current study examines how the sequencing of neoRT and ST affects metastatic dissemination. In a breast carcinoma model, tumors were exposed to different neoRT schedules (2x5Gy or 5x2Gy) followed by surgery at day 4 or 11 post-RT. The impact on the tumor microenvironment and lung metastases was evaluated through immunohistochemical and flow cytometry analyses. After 2x5Gy, early ST (at day 4 post-RT) led to increased size and number of lung metastases as compared to ST performed at day 11. Inversely, after 5x2Gy neoRT, early ST protected the mice against lung metastases. This intriguing relationship between tumor aggressiveness and ST timing could not be explained by differences in classical parameters studied such as hypoxia, vessel density and matrix remodeling. The study of tumor-related inflammation and immunity reveals an increased circulating NK cell percentage following neoRT as compared to non irradiated mice. Then, radiation treatment and surgery were applied to tumor-bearing NOD/SCID mice. In the absence of NK cells, neoRT appears to increase lung metastatic dissemination as compared to non irradiated tumor-bearing mice. Altogether our data demonstrate that the neoRT schedule and the ST timing affect metastasis formation in a pre-clinical model and points out the potential role of NK cells. These findings highlight the importance to cautiously tailor the optimal window for ST following RT.

Dequalinium blocks macrophage-induced metastasis following local radiation

A major therapeutic obstacle in clinical oncology is intrinsic or acquired resistance to therapy, leading to subsequent relapse. We have previously shown that systemic administration of different cytotoxic drugs can induce a host response that contributes to tumor angiogenesis, regrowth and metastasis. Here we characterize the host response to a single dose of local radiation, and its contribution to tumor progression and metastasis. We show that plasma from locally irradiated mice increases the migratory and invasive properties of colon carcinoma cells. Furthermore, locally irradiated mice intravenously injected with CT26 colon carcinoma cells succumb to pulmonary metastasis earlier than their respective controls. Consequently, orthotopically implanted SW480 human colon carcinoma cells in mice that underwent radiation, exhibited increased metastasis to the lungs and liver compared to their control tumors. The irradiated tumors exhibited an increase in the colonization of macrophages compared to their respective controls; and macrophage depletion in irradiated tumor-bearing mice reduces the number of metastatic lesions. Finally, the anti-tumor agent, dequalinium-14, in addition to its anti-tumor effect, reduces macrophage motility, inhibits macrophage infiltration of irradiated tumors and reduces the extent of metastasis in locally irradiated mice. Overall, this study demonstrates the adverse effects of local radiation on the host that result in macrophage-induced metastasis.

Concomitant Radiation Therapy and TGFβ Neutralizing Antibodies Alters Tumor Microenvironment and Promotes Tumor Regression

Transforming growth factor-β (TGFβ) has a broad range of pro-tumorigenic activities and immunosuppressive functions that have drawn considerable interest in cancer, especially since pharmaceutical inhibitors are in clinical trials. It is not clear how best to release the considerable potential of TGFβ inhibitors. Radiation induces TGFβ activity, which promotes effective response to DNA damage protecting cancer cells from radiation-induced cell death. RT is quite effective in eliciting immunogenic signals but is itself a source of immunosuppressive effects in the tumor microenvironment. Here we demonstrate that inhibition of TGFβ in pre-clinical a breast cancer model creates a tumor microenvironment that promotes immune response. Balb/c mice were inoculated with 105 non-metastatic TSA breast cancer cells into the flank and injected with 10mg/kg i.p. preclinical TGFβ neutralizing antibody 1D11 beginning on day 13 post tumor cell implantation. Twenty-four hours later, mice received 6 Gyx5 consecutive irradiation fractions. Tumor growth was caliper-measured thrice/week. Flow cytometry analysis and ex vivo cultures of primary cells were established to assess frequency and functional characteristics of immune cells. TGFβ neutralizing antibody treatment had no effect on tumor growth, however when combined with RT, tumor growth was substantially decreased relative to radiation treatment alone (p < 0.001). Notably, more than half of mice achieved complete tumor regression, suggesting activation of tumor immunity. TGFβ blockade decreases a splenic reservoir of CD11b+ myeloid-derived suppressor cells that mediate immunosuppression in the tumor microenvironment as well as CD11b+Gr1+/intF4/80+ precursors of tumor-associated macrophages. Immunoactivating IL12 was upregulated upon TGFβ inhibition while immunosuppressive IL10 and pro-angiogenic CXCL1 decreased. The number of splenic CD11c+ MHC Class I+ antigen presenting cells was dramatically reduced from irradiated tumor-bearing mice, but unaffected in mice receiving 1D11 antibody concomitant with RT. Tumor cell MHC Class I overexpression, which is induced by in vitro irradiation, was impaired after coculture with splenocytes from irradiated mice but not from mice receiving the dual treatment or 1D11 alone. TGFβ blockade sensitizes tumor cells to RT and generates a tumor microenvironment that promotes tumor control. TGFβ inhibition also alleviates tumor suppressive consequences of radiation and creates a pro-immunogenic signal. Together, these actions can achieve persistent tumor control.

Bone marrow-derived, endothelial progenitor-like cells as angiogenesis-selective gene-targeting vectors.

Human and mouse proliferation-competent, bone marrow or peripheral circulation derived endothelial progenitor-like cells (EPCs) were isolated, expanded and genetically engineered ex vivo to express the beta galactosidase (beta-gal), green fluorescence protein or thymidine kinase (TK) genes using retrovirus-mediated gene transfer. Genetically labeled EPCs were transplanted into sublethally irradiated tumor-bearing mice and were found to migrate to and incorporate into the angiogenic vasculature of growing tumors while maintaining transgene expression. Ganciclovir treatment resulted in significant tumor necrosis in animals previously administered TK-expressing EPCs with no systemic toxicity. These results demonstrate the feasibility of using genetically modified EPCs as angiogenesis-selective gene-targeting vectors and the potential of this approach to mediate non-toxic and systemic antitumor responses.

放射線生体照射の各臓器構成高級脂肪酸に及ぼす影響について

In order to study the effect of X-irradiation on the composition of fatty acids in the body of cancer bearing animals, at first solid Ehrlich carcinoma was transplanted into the right leg of mice and then 500 R/day of X-rays were irradiated on the right leg of the animals consecutively for 10 days (total dosage 5, 000R). The animals were divided into. three groups of the irradiated cancer bearing mice, non-irradiated cancer bearing mice and normal mouse control group. The fatty acid extraction was carried out by the method of Folch et al with (1) tumor and right leg muscle, (2) serum, and (3) liver, of each group, and the determination of the fatty acid composition was made by the gas-liquid chromatography.1. As the result it was found that the tumor tissue of the irradiated group revealed a greater quantity of linoleic acid than that of the non-irradiated cancer bearing group.2. The solid Ehrlich carcinoma of the right leg contained a larger amount of stearic acid than that in the right leg muscle of normal mice.3. As for the composition of total fatty acids in the liver and the serum, the percentage of linoleic acid was found greatest in (1) the control group of normal mice, followed by (2) irradiated tumor bearing mice, and (3) non-irradiated tumor bearing mice in the order mentioned.4. There seems to be some correlation between the cessation of tumor growth by irradiation and the distribution of linoleic acid.