Distribution of 99Tcm-rh-Annexin V and its relationship with expression of survivin and Caspase-3 in tumors after a single dose of chemotherapy

Objective: Recently, molecular imaging for detecting cellular apoptosis is developing rapidly. The aim of the study was to determine the effectiveness of imaging with 99Tcm labelled recombinant human Annexin V (99Tcm-rh-Annexin V) as a reflection of apoptosis in tumor, and related its distribution with expression of Survivin and Caspase-3 after a single dose of chemotherapy. Methods: Eight days after being inoculated with allogenic hepatoma cells (Hca-F25) into right axillary fossa, the mice (purebred 615) were randomly divided into two groups (control group A, n=9; and treated group B, n=10). Group B was received a single dose of chemotherapy intraperitoneally (cyclophosphamide, 150 mg/kg). Groups A and B were given 99Tcm-rh-AnnexinV (3.7 MBq·0.5 μg-1 per mouse) intravenously 20 h later. Four hours after 99Tcm-rh-Annexin V injection, the animals were imaged and sacrificed, and the tumor samples were weighed and the radioactivity was determined in a well-counter. The accumulation of 99Tcm-rh-Annexin V in tumor was expressed as the percentage activity of injection dose per gram of tissue (% ID/g). Tumor cell apoptosis was examined by terminal deoxynueleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) method, and the expression of Survivin and Caspase-3 in tumor were determined with immunohistochemical method. SPSS 10.0 was used for data analysis. Results: Single dose chemotherapy tsignificantly increased the tumor uptake of 99Tcm-rh-Annexin V [(0.478 ± 0.123)% ID/g vs (0.332 ± 0.061)% ID/g] and the positive number of TUNEL [(18.030 ± 5.600) cells/field vs (6.744 ± 2.325) cells/field], as well as the expression of Caspase-3 [(3.266 ± 0.482)% vs (2.387 ± 0.387)%, F was 10.502, 31.507, 18.971, respectively, all P < 0. 01], but the expression of Survivin was significantly higher in group A than in group B [(4.227 ± 0.636)% vs (3.407 ± 0.519)%, F=9.560, P<0.01]. The %ID/g in tumor correlated well with the positive number of TUNEL(n=19, r=0.858, P=0.000), and he expression of Survivin correlated negatively with the expression of Caspase-3 (r=-0.818, P=0.000). In group A and B, the distribution of 99Tcm-rh-Annexin V correlated positively well with the expression of Caspase-3 and negatively with the expression of Survivin (P<0.01). Conclusion: The distribution of 99Tcm-rh-Annexin V can not only reflect the extent of apoptosis, but also the change of Survivin and Caspase-3 expression in tumor after a single dose of chemotherapy. (authors)