Bone Tumors In Mice Research Articles

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

Targeted inhibition of T-cell factor activity promotes syndecan-2 expression and sensitization to doxorubicin in osteosarcoma cells and bone tumors in mice

Alterations of Wnt signaling appear to be involved in the pathogenesis of osteosarcoma, presenting mutations of adenomatous polyposis coli (APC) and epigenetic downregulation of Wnt inhibitory factor 1. However, the precise role of Wnt effectors in the bone cancer progression remains unclear. We previously showed that Wnt/β-catenin/T-cell factor (TCF) activation are responsible for the repression of syndecan-2, a key modulator of apoptosis and chemosensitivity in osteosarcoma cells, suggesting a role of Wnt signaling in chemoresistance. In this study, we investigated the functional relationship between syndecan-2, Wnt/β-catenin/TCF signaling and chemosensitivity in these cells. To this goal, we selected resistant osteosarcoma cells from sensitive human cell lines using repeated exposures to doxorubicin. In doxorubicin-responsive but not in doxorubicin-resistant-derived cells syndecan-2 expression was upregulated by doxorubicin treatment. Moreover, syndecan-2 overexpression restored the sensitivity to doxorubicin in resistant-derived cells. We found that syndecan-2 induction by doxorubicin is forkhead box protein O3A (Foxo3a)-dependent. Foxo3a overexpression resulted in increased syndecan-2 expression in sensitive and resistant-derived cells. Doxorubicin modulated Foxo3a binding on syndecan-2 gene promoter and induced Foxo-dependent inhibition of Wnt/TCF activity. Conversely, β-catenin/TCF activation impaired syndecan-2 induction by doxorubicin, indicating that Wnt signaling is competing with the action of the cytotoxic drug. However, β-catenin was also found to be required for Foxo3a activity. Consistently, Dickkopf 1 (DKK1) and secreted frizzled-related protein 1 (sFRP-1) altered doxorubicin action in sensitive cells, whereas inhibition of TCF activity strongly decreased cell viability and increased sensitivity to doxorubicin in sensitive and resistant cells. TCF inhibition also increased the effect of doxorubicin treatment in an orthotopic bone tumor model in mice. Altogether, these data provide evidence that the repression of syndecan-2 by Wnt/β-catenin/TCF signaling contributes to the resistance of osteosarcoma cells to doxorubicin and suggest that TCF inhibition may represent a novel therapeutic strategy in osteosarcoma.

Potentiation of acute morphine‐induced analgesia measured by a thermal test in bone cancer‐bearing mice

Agonists of μ-opioid receptors are currently used in the management of cancer pain. However, several data suggest that the analgesic effect of morphine can diminish during the development of experimental tumors. By using a thermal test, we have studied whether the analgesic effect evoked by morphine is altered in mice bearing two painful bone tumors. The analgesic effect evoked by systemic morphine remained unaltered after the intratibial inoculation of B16-F10 melanoma cells and was potentiated after the inoculation of NCTC 2472 osteosarcoma cells. Although the number of spinal μ-opioid receptors measured by western blot studies was not augmented in osteosarcoma-bearing mice, the analgesia evoked by intrathecal (i.t.) morphine was also enhanced. The analgesic response produced by the spinal administration of the Gi/o protein activator mastoparan was amplified, whereas the analgesic response evoked by the i.t. administration of the N-type calcium channel blocker ω-conotoxin remained unaltered. The efficacy of the GIRK channel blocker tertiapin-Q to antagonize the analgesic effect produced by a maximal dose of morphine was also increased in osteosarcoma-bearing mice. Our results seem to indicate that the analgesic effect of morphine on thermal nociception can be enhanced in response to the development of particular bone tumors in mice, being this potentiation probably related to a greater efficacy of the transduction system driven by Gi/o proteins and GIRK channels.

Biodistribution of 225Ra citrate in mice: retention of daughter radioisotopes in bone

Alpha-particle-emitting radionuclides have potential for therapy of localized disease due to their high linear energy transformation and short pathlengths. Radiometals that home naturally to bone can be exploited for this purpose, and 223Ra ( t 1/2=11.4 days) recently has been studied for therapy of bone tumors in mice and rats. Actinium-225 ( t 1/2=10 days) is also an attractive radioisotope for endoradiotherapy. In a single decay of a 225Ac nucleus and its subsequent decay daughters, over 27 MeV (∼90% of total energy) is released by sequential emission of four α particles, ranging in energy from 5.7 to 8.4 MeV. Although Ac 3+ does not home naturally to bone, its parent radioisotope 225Ra (β −, t 1/2=15 days) can be used as an in vivo source for 225Ac. Thus, injection of 225Ra takes advantage of the bone-homing properties of radium coupled with the significant amount of energy released from the 225Ac decay chain. Our data confirm that a large fraction of radium citrate injected intravenously into mice localizes rapidly in bone. Injected doses per gram (ID/g) for 225Ra range from 25% in skull to about 10% in sternum. Once deposited, the 225Ra remains in the bone with a biological half life of >40 days. Furthermore, >95% of the daughter radioisotope, 225Ac, is retained in the bone. However, a significant fraction of one of the daughter radioisotopes, 213Bi, is found in kidney. The biodistribution data indicate that 225Ra injection should be a powerful agent for killing cells associated with bone; however, the toxicity of this radioisotope which is similar to that of other α emitters limits the dose that can be tolerated.

An experimental investigation into the development of callus and induced bone tumours in mice studies by histological and enzyme histochemical methods.

An experimental investigation into the development of callus and induced bone tumours in mice studies by histological and enzyme histochemical methods.

Relative biological effectiveness of internal emitters.

Permissible levels of exposure to radioactive materials have been based in large part upon two sets of comparisons. In the first, the radiotoxic hazards of the various isotopes are evaluated relative to radium in experimental animals. In the second, extrapolations are made to man through radium as the common link, since the latent effects of that element are known from individuals who have carried small but measurable body burdens for many years. In this work the mouse has proved to be a very useful experimental animal, particularly when relatively large populations are required. The data accumulated in such studies make possible an evaluation of the relative biological effectiveness (RBE) of different radioisotopes according to a number of criteria. The effects of several alpha-emitters upon survival and upon the incidence of malignant bone tumors in mice have been reported previously (1). Subsequent experiments with several beta-emitters have now progressed to the point where preliminary comparisons can...

The Gross Pathology of Spontaneous Bone Tumours in Mice

An account of the origin and development of an inbred strain of mice with a high incidence of bone tumours has already been given (1), and a preliminary description of some of the more important characteristics of the lesions has also appeared (2). The object of the present communication is to illustrate in more detail the main features, such as the sites and types of lesions, and other points of interest and importance. The material has been obtained over a period of five years during the development of the high-incidence strain, and comes from the main Simpson stock, the earlier selected and inbred sarcoma lines, as well as from the later inbred strain which is now in its eighth generation. Bone lesions have been found in more than 300 mice, and the majority of these have been examined microscopically (see following paper).

The Histology of Spontaneous Bone Tumours in Mice

The gross pathology of bone tumours occurring spontaneously in an inbred strain of mice has already been described (4). In general, these appear to represent almost every possible phase of proliferative activity of the osteoblast; they may occur in any bone, and several or even all the bones in an animal may be affected. It is no exaggeration to say that every type of histologic change may occasionally be illustrated from a single mouse. The tumours from the first 106 sarcoma mice observed have been reexamined in an attempt to classify them according to the predominating type of cell. A number of these animals had multiple lesions of different types. Mouse 1688, for example, had a spindle-celled tumour of the tibia and an ossifying tumour involving the spine and ribs. Bone and osteoid tissue were the main features of tumours of the spine, ilium, and right femur of mouse 2706, which also had almost pure spindle-celled tumours of the rib and left femur. Mouse 2810 had a giant-celled tumour of the tibia and an osteoma of the spine. A number of similar examples might be quoted from the records. Of the 118 tumours, 89 consisted principally of bone and osteoid tissue; 20 were predominantly spindle-celled growths; 5 were mainly giant-celled tumours; and in only one was cartilage the principal feature, although it was present in 5 tumours of other types. There were two tumours in which spindle cells and osteoid tissue were present in equal amounts, and these must be classed as mixed tumours (one of these also contained cartilage), while one tumour was mainly round-celled, with some osteoid tissue and cartilage in addition. Giant cells were seen in 22 tumours altogether, and in only 10 tumours were there no signs of osteogenesis. The accompanying illustrations show the main types of tissue encountered.

A Sex-Difference in the Incidence of Bone Tumours in Mice

In a previous account (1) of the development of an inbred strain of mice with a high incidence of spontaneous bone tumours, it was mentioned that sarcomata in general seem to occur more frequently in the females than in the males of the Simpson Strain. Figures were given for sarcomata of all types and in all sites in the entire Simpson stock maintained in this laboratory, including those branches which had been inbred to produce a strain of high sarcoma incidence. Recent observations on the inbred Sarcoma Strain have confirmed the earlier observations as to sex incidence. Originally developed from three females and one male, which had all produced bone tumours, the strain is now in its eighth generation of brother-to-sister inbreeding, a number of separate lines being continued. Only five other instances of double-sarcoma matings have so far occurred within the strain. The tumour arising from bone, of which a very brief description has been given (2), is the preponderant neoplasm in the strain; no other type of sarcoma has yet been found. Up to March 17, 1938, there were 195 deaths among the mice of sarcoma age belonging to F1 and subsequent generations; among these, there were 104 instances of bone tumour, an incidence of 53.3 per cent. Of the total number of animals dying, 97 were females and 98 males. Bone tumours appeared in 75 of the females, an incidence of 77.3 per cent, and in only 29 of the males, or 29.6 per cent.

Hereditary Bone Tumours in Mice

Hereditary Bone Tumours in Mice