Non-invasive bioluminescent detection of prostate cancer growth and metastasis in a bigenic transgenic mouse model
ABSTRACT We previously established a bioluminescent transgenic mouse model, sPSA-Luc, with luciferase gene expression restricted to the prostate under the control of the supra prostate-specific antigen (sPSA) promoter. We now assess the feasibility of generating bigenic mice, TRAMP-Luc, with the sPSA-Luc as the founder strain crossbred with TRAMP (transgenic adenocarcinoma mouse prostate) mice, to evaluate non-invasively the metastatic potential of prostate tumors.
TRAMP-Luc mice were obtained as [C57BL/6 TRAMP x FVB sPSA-Luc] F1 offspring. Tumor development in 10 TRAMP-Luc males was followed by bioluminescence imaging from 8 to 24 weeks of age. Immunohistochemical (IHC) staining for T antigen (Tg), androgen receptor (AR), luciferase and/or pathological analysis verified the tumor distribution in the imaged tissues including prostate gland, lymph node and bone.
Group I animals that presented with no grossly visible tumors showed prostate-confined bioluminescence with slightly increased signal intensity with age. Group II animals that developed large tumors displayed a widely distributed and biphasic bioluminescence pattern. The peak was reached between 10 and 14 weeks of age, then markedly decreased or even disappeared beyond week 16, except for one mouse that showed an increased bioluminescence signal at the jaw bone and hind limbs at week 22. These tumors were shown by IHC to contain Tg but lost AR and luciferase beyond week 16 in poorly differentiated prostate tumors.
A direct correlation between bioluminescence emission and AR expression was found in TRAMP-Luc tumor progression model. This model allows non-invasive imaging of prostate cancer metastases to bone and soft tissues.
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ABSTRACT: The treatment paradigms for head and neck squamous cell cancer (HNSCC) are changing due to the emergence of Human Papillomavirus (HPV)-associated tumors possessing distinct molecular profiles and responses to therapy. While patients with HNSCCs are often treated with radiotherapy, preclinical models are limited by the ability to deliver precise radiation to orthotopic tumors and to monitor treatment responses accordingly. To better model this clinical scenario, we developed a novel autochthonous HPV-positive oral tumor model to track responses to small molecules and image guided radiation. We used a tamoxifen-regulated Cre recombinase system to conditionally express the HPV oncogenes E6 and E7 as well as a luciferase reporter (iHPV-Luc) in the epithelial cells of transgenic mice. In the presence of activated Cre recombinase, luciferase activity, and by proxy, HPV oncogenes were induced to 11-fold higher levels. In triple transgenic mice containing the iHPV-Luc, K14-CreERtam and LSL-Kras transgenes, tamoxifen treatment resulted in oral tumor development with increased bioluminescent activity within 6 days that reached a maximum of 74.8 -fold higher bioluminescence compared to uninduced mice. Oral tumors expressed p16 and MCM7, two biomarkers associated with HPV-positive tumors. After treatment with rapamycin or image guided radiotherapy, tumors regressed and possessed decreased bioluminescence. Thus, this novel system enables us to rapidly visualize HPV-positive tumor growth in order to model existing and new interventions using clinically relevant drugs and radiotherapy techniques.Cancer Research 02/2014; 74(7). DOI:10.1158/0008-5472.CAN-13-2993 · 9.28 Impact Factor
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ABSTRACT: Prostate cancer is the most common primary tumor and the second leading cause of cancer-related deaths in men in the United States. Prostate cancer bone metastases are characterized by abnormal bone remodeling processes and result in a variety of skeletal morbidities. Prevention of skeletal complications is a crucial element in prostate cancer management. This study investigated prostate cancer-induced alterations in the molecular composition and morphological structure of metastasis-bearing bones in a mouse model of prostate cancer using Raman spectroscopy and micro-computed tomography (microCT). LNCaP C4-2B prostate cancer cells were injected into the right tibiae of 5-week old male SCID mice. Upon sacrifice at 8 weeks post tumor inoculation, two out of the ten tumor-bearing tibiae showed only osteoblastic lesions in the radiographs, 4 osteolytic lesions only and 4 mixed with osteoblastic and osteolytic lesions. . Carbonate substitution was significantly increased while there was a marked reduction in the level of collagen mineralization, mineral crystallinity, and carbonate:matrix ratio in the cortex of the intact tumor-bearing tibiae compared to contralateral controls. MicroCT analysis revealed a significant reduction in bone volume/total volume, trabecular number and trabecular thickness, as well as significant increase in bone surface/volume ratio in tibiae with osteolytic lesions, suggesting active bone remodeling and bone loss. None of the changes in bone compositional properties were correlated with lesion area from radiographs or the changes in bone architecture from microCT. This study indicates that LNCaP C4-2B prostate cancer metastases alter bone tissue composition independent of changes in architecture, and altered bone quality may be an important contributor to fracture risk in these patients. Raman spectroscopy may provide a new avenue of investigation into interactions between tumor and bone microenvironment.Bone 07/2013; 56(2). DOI:10.1016/j.bone.2013.07.006 · 4.46 Impact Factor
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ABSTRACT: Cabazitaxel (Jevtana) has been approved for the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, most patients progress and become chemoresistant, which remains a major challenge in the management of advanced PCa. In this study, we investigated whether genistein, an isoflavone abundant in soy products, could sensitize mCRPC cells to cabazitaxel treatment in experimental models. The in vitro and in vivo effect of genistein in enhancing the response of mCRPC cells to cabazitaxel chemotherapy was evaluated in experimental models. Genistein increases the expression of pro-apoptotic protein Bax, activates apoptotic signals, and enhances the response to cabazitaxel treatment in mCRPC cells. In a PC3-luciferase xenograft model, the combined treatment with genistein and cabazitaxel significantly retarded the growth of mCRPC when compared to vehicle control, cabazitaxel, or genistein. Tissue staining confirmed the in vivo effect of genistein on the induction of Bax and activation of apoptosis. This study provided the first preclinical evidence supporting that genistein could be beneficial in improving cabazitaxel chemotherapy in mCRPC. Prostate © 2013 Wiley Periodicals, Inc.The Prostate 08/2013; DOI:10.1002/pros.22705 · 3.57 Impact Factor