Evaluation of carbon-14-colchicine biodistribution with whole-body quantitative autoradiography in colchicine-sensitive and -resistant xenografts.

ABSTRACT

UNLABELLED Quantitative autoradiography (QAR) with radiolabeled monoclonal antibodies in xenografted animals has been extensively described in the past, either on individual tissues or on the whole body. We applied whole-body QAR to identify multidrug resistant tumors using 14C-colchicine (14C-CHC). METHODS: Two groups of five animals each were xenografted with CHC-sensitive and CHC-resistant human neuroblastoma cells. Animals were injected intravenously with 4 microCi/0.11 mumole 14C-CHC per gram of body weight and sacrificed after 60 min. Whole-body QAR was carried out using 25-microns thick sections. RESULTS: Fusion images allowed direct comparison of 14C-CHC uptake in tumor and nontumor tissues. Mean 14C-CHC distribution in sensitive and resistant tumors was 882.0 +/- 43.6 and 399.6 +/- 157.7 nCi/g corresponding to 24.5 +/- 1.21 and 11.1 +/- 4.38 nmole/g, respectively (p < 0.001), with normal tissue distribution in both groups being similar. Three-dimensional QAR showed that the uptake of 14C-CHC was in the cellular zones of the tumor. This method has potential in biodistribution studies of novel radiopharmaceuticals such as 14C-CHC. CONCLUSION: These studies further suggest that PET imaging of 11C-CHC is feasible to distinguish between sensitive and resistant tumor deposits in vivo.