Molecular Imaging Of GFP-Expressing Transplanted Tumor In Vivo

Objective: An animal model bearing transplanted Lewis lung carcinoma (LLC) in which green fluorescent protein(GFP)gene were highly expressed h as b een d eveloped,thus a n ew w ay for t he r esearch o n tumors' growth metastasis and the effect of the treatment using medical imaging at the early stage of tumor development is provided ,which is not only noninvasive,whole body but real time and subsequently at the same time ,based on this model ,the inhibitory effect of endostatin on tumor's endogenesis as well as on the expression of VEGF and Bcl-2 were observed . Methods: The pLEIN-CMV-GFP vector was transducted into PT67 packaging cell line to make the retroviral production ,and tested the titre of the virus ,then transfected GFP genes into LLC cells. G418 was used as selection ,in order to get the stable and high expression of GFP in LLC cells .After these GFP labeled cells were harvested, 0.2 ml cell suspension(2 X 106cells / ml )was injected subcutaneously to the back of the mude mice and grew, in vivo fluorescent imaging system was used to imaged them later on in different periods of time since injection ,mude mice were divided into three groups ,A, B, C ,endostation were administrated into the tumors in group B, and CTX were used in groups C as positive control , physiological saline were administrated in group A as negative control , the tumor inhibition rates and microvessel density(MVD) were estimated to value the treating effect, immunohistochemistry was also used to determine the expression of VEGF and Bcl-2. Results: With G418 selection , GFP genes could be expressed highly and stablely in LLC cells ,after transplantation ,not only tumors but aslo the vessles of the transplantedtumor could be seen, developing with clear image. The tumor inhibition rates in group B is high than in group A ,but there is no significant difference between that in group B and C, MVD and expression of VEGF and Bcl-2 decreased in group B compared with group A, but the decreasion in group B campared with group C is of no significance (P > 0.05) .. Conclusions: This animal model with GFP expressed LLC cells for molecular imaing is stable, and relatively uncomplex to make,which provides us a new way with its advantages of real time> noninvasive and in vivo ,which is a much more direct way to study angiogenesis of tumor compared with previous immunohistochemistry methods. Endostatin has obviously inhibiting effect on mouse LLC transplanted tumor, and can reduce the expression of VEGF and Bcl-2 in tumors .