Distribution of ⁹⁹Tc^m-rh-AnnexinⅤand Its Relationship with Expression of bcl-2、bax in Tumor After a Single Dose of Chemotherapy

Objective To determine the effectiveness of imaging with 99mTc labelled recombinant human annexinⅤ(99mTc-rh-annexinⅤ) as a reflection of the degree of apoptosis in tumor，and investigate the distribution of 99Tcm-rh-AnnexinⅤand its relationship with expression of bcl-2、bax after the single dose of chemotherapy. Methods Eight days after being inoculated with allogenic hepatoma cells(Hca-F25) into the subcutaneouly of the right axillary fossa, the mice (purebred 615) were randomly divided into tow groups (group A was control group, n=9；group B was treated group, n=10). Group B was received a single dose of chemotherapy intraperictoneally (cyclophosphamide, 150mg/kg). Group A and group Bwere injected 99mTc-rh-annexinⅤ(3.7MBq/0.5μg/per mouse) intravenously 20 hrs later. 4 hrs after 99mTc-rh-annexinⅤ injection, the animals were imaged and sacrified, the tumor samples were weighed and the radioactivity was determined with a well-type scintillation counter. The accumulation of 99mTc-rh-annexinⅤ in tumor was expressed as the %ID/g(percentage activity of injection dose per gram of tissue).Tumor cell apoptosis was examined by TUNEL methods, and the expression of bcl-2 and bax in tumor were determined with immunohistochemical methods. Results Single dose of chemotherapy significantly increased the tumor uptake of 99mTc-rh-annexinⅤ and the positive number of TUNEL, as well as the expression of bax (P<0.01). The expression of bcl-2 had no significant difference in group A and group B(P=0. 220), but the bcl-2/bax was significantly high in group A than in group B(P<0.01). The %ID/g in tumor correlated well with the positive number of TUNEL in group A and group B(r=0. 801, r=0.769), but the expression of bcl-2 had no relationship with the expression of bax. In group A, the expression of bcl-2 and bax had no relationship with the %ID/g and the positive number of TUNEL in tumor. In group B, the expression of bax correlated well with the %ID/g and the positive number of TUNEL(r=0. 849, r=0.652), but the bcl-2/bax correlated negatively with %ID/g and the positive number of TUNEL(r=-0. 820, r=-0. 694). Conclution The distribution of 99mTc-rh-annexinⅤcan not only truly reflected the degree of apoptosis in tumor, but also the change of bax expression after the single dose of chemotherapy.