Radiolabeling of Bleomycin-Glucuronide with 131I and Biodistribution Studies Using Xenograft Model of Human Colon Tumor in Balb/C Mice

Bleomycin-glucuronide (BLMG) is the glucuronide conjugate of BLM. In the present study, BLMG was primarily enzymatically synthesized by using a microsome preparate separated from rat liver, labeled with I-131 by iodogen method with the aim of generating a radionuclide-labeled prodrug, and investigated its bioaffinities with tumor-bearing Balb/C mice. Quality control procedures were carried out using thin-layer radiochromatography and high-performance liquid chromatography. Tumor growing was carried out by following Caco-2 cell inoculation into mice. Radiolabeling yield was found to be about 65%. Results indicated that I-131-labeled BLMG (I-131-BLMG) was highly stable for 24 hours in human serum. Biodistribution studies were carried out with male Albino Wistar rats and colorectal adenocarcinoma tumor-bearing female Balb/C mice. The biodistribution results in rats showed high uptake in the prostate, the large intestine, and the spinal cord. In addition to this, scintigraphic results agreed with those of biodistributional studies. Xenography studies with tumor-bearing mice demonstrated that tumor uptakes of I-131-BLM and I-131-BLMG were high in the first 30 minutes postinjection. Tumor-bearing animal studies demonstrated that I-131-BLMG was specially retained in colorectal adenocarcinoma with high tumor uptake. Therefore, I-131-BLMG can be proven to be a promising imaging and therapeutic agent, especially for colon cancer in nuclear medical applications.