Abstract #4001: Study of actin depolymerizing factor (ADF)/cofilin on tumorigenesis by multi-modality reporter gene imaging
Authors: Cheng-Han Tsai, Jeng-Jong Huang, Yi-Jang Lee
Journal: Cancer Research (2009)

Purpose: Use multiple non-invasive optical imaging techniques to detect whether ADF/cofilin can affect tumor growth in the experimental animal model. Materials and Methods: An established stable human H1299 non-small lung carcinoma cell line conditionally express cofilin (HCOXP cells, H1299 withcofilin over-expression) by the tet-on gene expression system. Cofilin expression was determined by western blot. Furthermore, we stably transfected two tetracycline regulatable constructs containing HSV1-TK gene and luciferase(pBI-tk-Luc) or EGFP(pBI-tk-EGFP) separately into HCOXP cells which were named HCOXP-Luc and HCOXP-EGFP cells respectively. For these three cell line, 5*106 cells were s.c. implanted into every NOD/SKID mice by subcutaneous injection. The mice after the xenograft were separated and treated with or without doxycycline. Bioluminescence and EGFP images were collected by using IVIS 50. As soon as the tumor formed, some of mice were changed to be fed with doxycycline and the others not. Compare tumors size measured by vernier caliper, photon signal intensity acquired by IVIS 50 persisted for 10 weeks and cofilin expression by immunohistochemistry after sacrificing some mice. Results: We have demonstrated that cofilin over-expression would cause tumor growth inhibition in NOD/SKID mice before. We have been developing a system to record dynamics of cofilin over-expression on tumor growth compared by non-invasively detecting the bioluminescent signals using IVIS 50 system after mice were injected luciferin. The results showed that signal was increased in mice fed with doxycycline for the first week. The signal was gradually reduced and completely diminished during five weeks of treatment. No signal was detected in implanted mice fed with normal water. Correspond to BLC results, the EGFP signals could be obtained from the mice fed with doxycycline and the other group couldn\#8217;t. Tumors only formed on mice fed with normal drinking. Both BLC and EGFP signals could be detected in mice treated by doxycycline in one week but the signal was gradually weakened and vanished entirely in seven weeks. The same tendency was happened on tumors growth rate which was reduced after feeding doxycycline. IHC stained results showed that cofilin had higher expression compared with tumors from the control group. Conclusions: Luciferase and EGFP gene is reporter gene used as indicators to trace the tumor kinetics on mice, tumors were formed in these mice not in those fed with doxycycline which have bioluminescent or EGFP signal. After tumor forming, we have demonstrated photon signals accompanied tumor growth. We conclude that cofilin over-expression can repress the growth of xenograft tumor, and the bioluminescent or EGFP imaging is a convenient tool to real-time measure the inhibition kinetics. For HSV1-TK expression detected by microPET are not clear, we are desire to have a reliable image in the future.  Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 4001.