Antitumor effects of 32P-chromic-poly (L-lactide) brachytherapy in nude mice with human prostate cancer

The aim of the present study was to investigate the antitumor effects and tissue distribution of 32P-chromic-poly (L-lactide) (32P-CP-PLLA) in nude mice with human prostate cancer. Tumor models were obtained by transplantation of PC-3M tumor cells into male BALB/c nude mice. Animals were randomly divided into control, 32P-chromic phosphate (32P-CP) colloid and 32P-CP-PLLA groups (all n=20). A series of indices were investigated, including apoptosis of tumor cells, rate of apoptosis, expression of caspase 3 and 8, biodistribution and intratumoral concentration of 32P-CP-PLLA, intensity of radioactivity, tumor volume and microvessel density (MVD). Highly concentrated radioactivity of 32P-CP-PLLA in the tumor mass was detected by single photon emission computed tomography (SPECT) scanning. The residual activities of the 32P-CP-PLLA and 32P-CP colloid groups were 3.02±0.32 and 1.76±0.31 MBq, respectively, on day 14 following treatment. The tumor inhibition rates were 67.24±3.55 and 55.92±7.65%, respectively (P<0.01). Necrotic changes, in conjunction with apoptosis, were observed in the treatment group. MVD values for the 32P-CP-PLLA and 32P-CP colloid groups were 28.24±10.07 and 36.15±11.06, respectively. 32P-CP-PLLA showed an excellent capacity for killing tumor cells, inducing apoptosis and inhibiting angiogenesis.