Luciferase bioluminescence imaging monitoring gene therapeutic effect of apoptosis-inducing ligand for lung cancer A549 cells nude mice transplantation tumor in vivo

Objective: To detect the expression and effect of human tumor necrosis factor related apoptosis-inducing ligand (hTRAIL) in vivo,by using a novel double expressing adenoviral vector encoding hTRAIL and firefly luciferase (luc) gene (ad-luc-hTRAIL), in which luc was used as reporter gene. Methods: Lung cancer A549 cell xenografts in 16 nude mice models were established in subcutaneous inoculation way, the adenovirus vectors (ad-luc-hTRAIL, ad-hTRAIL, ad-luc) and phosphate buffer saline (PBS) (n=4) as control were injected into tumor respectively. The size of the tumor was measured at different time points (4, 7, 10, 14, 21, 28 d) after injection. The activity of luciferase in surface of the tumor was detected in vivo by using high-sensitivity cooled-charged coupled device (CCD) camera. The expression of hTRAIL was demonstrated by immunohistochemistry staining after sacrificing the animals at different time points, and immunohistochemical scores (IHS) were measured. The apoptosis rate of tumor cells was detected by using TUNEL and calculated. Analysis of variance, the paired t test and linear correlation analysis was used for the statistics. Results: The growing speed of tumour xenografts was more slowly in ad-luc-hTRAIL and ad-hTRAIL groups than PBS group (t=2.71, 2.72, P<0.05). The tumor volumes of ad-luc-hTRAIL, ad-hTRAIL, ad-luc and PBS groups 28 days after injection were (208.4 ± 42.3), (181.5 ±23.9), (403.1 ± 54.0) and (427.0 ± 59.3) mm³, respectively. There was no significant difference between ad-luc group and PBS group (t=2.07, P>0.05). The expression of luciferase in ad-luc-hTRAIL group reached its peak at 7^th day (1.37 ± 1.04), and then decreased quickly. The IHS and apoptosis rate in ad-luc-hTRAIL and ad-hTRAIL groups reached their peaks at 7^th day, the peak values of IHS were 6.25 ±2.06 and 6.5 ± 2.89, the peak values of apoptosis rate were (60.75 ± 8.06)% and (61.50 ± 8.47)%,respectively. The amount of luciferase expression (absolute number of photons detected by CCD camera) was linear positive correlated with IHS and apoptosis rate (r_photons/IHS=0.942, r_photons/rate=0.842, r_IHS/rate=0.887, P<0.05). Conclusion: The target gene hTRAIL can be transfected into lung cancer A549 cell xenografts nude mice models efficiently with a high level expression, and the therapeutic effect of hTRAIL can be monitored by detecting the expression of luc. (authors)