Development Of Tumor Nodules Research Articles

Morphology, Biochemistry, and Pathophysiology of MENX-Related Pheochromocytoma Recapitulate the Clinical Features.

Pheochromocytomas (PCCs) are tumors arising from neural crest-derived chromaffin cells. There are currently few animal models of PCC that recapitulate the key features of human tumors. Because such models may be useful for investigations of molecular pathomechanisms and development of novel therapeutic interventions, we characterized a spontaneous animal model (multiple endocrine neoplasia [MENX] rats) that develops endogenous PCCs with complete penetrance. Urine was longitudinally collected from wild-type (wt) and MENX-affected (mutant) rats and outputs of catecholamines and their O-methylated metabolites determined by mass spectrometry. Adrenal catecholamine contents, cellular ultrastructure, and expression of phenylethanolamine N-methyltransferase, which converts norepinephrine to epinephrine, were also determined in wt and mutant rats. Blood pressure was longitudinally measured and end-organ pathology assessed. Compared with wt rats, mutant animals showed age-dependent increases in urinary outputs of norepinephrine (P = .0079) and normetanephrine (P = .0014) that correlated in time with development of tumor nodules, increases in blood pressure, and development of hypertension-related end-organ pathology. Development of tumor nodules, which lacked expression of N-methyltransferase, occurred on a background of adrenal medullary morphological and biochemical changes occurring as early as 1 month of age and involving increased adrenal medullary concentrations of dense cored vesicles, tissue contents of both norepinephrine and epinephrine, and urinary outputs of metanephrine, the metabolite of epinephrine. Taken together, MENX-affected rats share several biochemical and pathophysiological features with PCC patients. This model thus provides a suitable platform to study the pathogenesis of PCC for preclinical translational studies aimed at the development of novel therapies for aggressive forms of human tumors.

Abstract 3946: Saracatinib inhibits human prostate cancer cell bone metastases in a xenograft model.

Abstract Background: In advanced prostate cancer (PCa), cells escape from the primary tumor and enter the bloodstream. These circulating cells preferentially target the axial skeleton and can form bone metastases. This results in weakened bones, spinal compressions, and fractures. Patients experience pain and other bone-related events that increase mortality and decrease quality of life. Therefore, identifying factors that lead to cancer progression, such as areas of hypoxia in the tumor microenvironment, will be crucial to developing strategies to inhibit the spread of malignant cells to distant sites. Efforts to interfere with early steps in the metastatic cascade have led to the development of promising small molecule targeting agents. One such agent is the tyrosine kinase inhibitor (TKI), saracatinib, shown to inhibit activation of Src and other kinases thought to be involved in cancer cell dissemination. The aim of these studies was to use aggressive, human PCa cells (PC-3ML), selected for their ability to form bone tumors in mice, to investigate the effects of various agents shown to interfere with metastatic activity. Methods: PC-3ML cells (a gift from A. Fatatis, Drexel University), expressing Green Fluorescent Protein (GFP) and luciferase (Luc), were injected into the left ventricle of male nude mice, using a closed-chest technique, to ensure that they bypass the lungs and circulate throughout the body. Prior to injection, cells were subjected to either hypoxia for 6 or pretreated for 24 hr with saracatinib. Immediately after injection, mice were placed in an in vivo imaging system (Xenogen IVIS, Caliper Life Sciences) to verify that the cells had disseminated throughout the body. This ensured that only successfully injected mice were randomization to treatment groups. Additional images were collected weekly thereafter to monitor the location and development of tumor nodules. Three weeks post-injection, mice were euthanized and tissues expressing Luc were collected, including bones of the legs, mandible and spine. The bones were fixed and decalcified, followed by flash freezing in OCT freezing medium. Serial frozen sections were then evaluated for GFP expressing cells using a fluorescent stereoscope. Results: Tumor cell deposits were almost always found in bone, frequently in the tibial-femoral joint, scapula-humerus joint, spine, and mandible. Mice injected with PC-3ML cells pretreated with saracatinib had fewer metastases and cells exposed to hypoxia for 6 hr prior to injection had more metastases, on average, than control cells, as predicted by in vitro assays. Conclusions: Intracardiac injection of GFP- and Luc- labeled PC-3ML cells resulted in skeletal metastases that could be monitored in mice over time using an in vivo imaging system and in tissue sections by fluorescent microscopy. The studies verified in vitro data showing that hypoxia can enhance, and saracatinib inhibit, metastatic activity. Citation Format: Lori P. Rice, Christine Pampo, Sharon Lepler, Dietmar W. Siemann. Saracatinib inhibits human prostate cancer cell bone metastases in a xenograft model. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3946. doi:10.1158/1538-7445.AM2013-3946

Targeting Toll-like Receptor 9 with CpG Oligodeoxynucleotides Enhances Tumor Response to Fractionated Radiotherapy

Synthetic oligodeoxynucleotides containing unmethylated CpG motifs detected by Toll-like receptor 9 of dendritic cells and B cells have potent immunomodulatory effects. CpG oligodeoxynucleotides induce cytokines, activate natural killer cells, and elicit T-cell responses leading to antitumor effects, including improved efficacy of chemotherapeutic agents and, as we reported recently, synergy between CpG oligodeoxynucleotide 1826 and single-dose radiotherapy of an immunogenic mouse fibrosarcoma. The present study extends this finding to the fractionated radiotherapy of the fibrosarcoma tumor and assesses the ability of CpG oligodeoxynucleotide 1826 to increase the radioresponse of a tumor (nonimmunogenic fibrosarcoma). The experiments used a murine immunogenic fibrosarcoma tumor, fibrosarcoma growing in the leg of mice, and response to radiotherapy was assessed by tumor growth delay and tumor cure rate (TCD50, radiation dose yielding 50% tumor cure). Multiple s.c. peritumoral or i.t. administrations of CpG oligodeoxynucleotide 1826 at a dose of 100 microg per mouse were given when established tumors were 6 mm in diameter. Local tumor irradiation was initiated when tumors grew to 8 mm in diameter; radiation was delivered in 1 to 9 Gy fractions given twice daily separated by 6 to 7 hours for 5 consecutive days to achieve a total dose of 10 to 90 Gy. CpG oligodeoxynucleotide 1826, given as a single agent, had only a small antitumor effect, but it dramatically enhanced fibrosarcoma response to radiotherapy. Although 83.1 (79.2-90.0) Gy total dose were needed to achieve tumor cures in 50% of mice treated with radiotherapy alone, only 23.0 (11.5-32.7) Gy total dose were needed in mice treated with both CpG oligodeoxynucleotide 1826 and radiotherapy. The magnitude of potentiation of tumor radioresponse at the TCD50 level was by a factor of 3.61, a much higher value than that (a factor of 1.93) that we reported for single-dose radiotherapy. Mice cured of their tumors by combined CpG oligodeoxynucleotide 1826 plus radiotherapy were highly resistant to s.c. tumor take or development of tumor nodules in the lung from i.v. injected tumor cells when rechallenged with fibrosarcoma cells 100 to 120 days after the treatment, suggesting the development of a memory response. CpG oligodeoxynucleotide 1826 also increased radioresponse of the nonimmunogenic fibrosarcoma tumor by a factor of 1.41 and 1.73 when CpG oligodeoxynucleotide 1826 was given s.c. and i.t., respectively. These findings show that CpG oligodeoxynucleotides are highly potent enhancers of tumor response to both single-dose and fractionated radiation and as such have potential to improve clinical radiotherapy.