99mTc-LHRH in tumor receptor imaging

Abstract

Detection of gonadotropin-releasing hormone (GnRH) also known as luteinizing hormone-releasing hormone (LHRH) in the relevant tumor tissue and normal tissues and organs in vivo expression was investigated. To examine the method of direct radio labeling of LHRH by99mTc with relatively high radiochemical purity and stability, screening the best labeling conditions, to establish a simple and reliable method of preparation of99mTc-LHRH was undertaken. The detection of radioisotope-labeled LHRH distribution in mice, LHRH receptor imaging for the study and treatment of cancer basis were evaluated. i) Immunohistochemical staining test was used in 23 patients with hepatocellular carci-noma (HCC), 20 patients with breast cancer, 10 patients with prostate cancer, 20 patients with lung cancer, 20 patients with endometrial cancer tumor cells and normal tissue LHRH-R De Biaoda levels; ii) pre-tin method use direct labeling of LHRH, marking completion of saline or human serum were added at room temperature, the chromatography was measured at different times, to calculate the rate of labeled product and the radiochemical purity of the label, in vivo observation of its stability, and comparative analysis of selected optimal condition; iii) rat pituitary cell membrane protein, the product of in vitro radio-receptor marker analysis, through the satura-tion and inhibition experiments, was used to test its receptor binding activity; iv) Ch-T method labeled125 I-LHRH, tail vein injection of normal mice at different times were sacrificed, blood and major organs were determined and calculated per gram organization percentage injected dose rate (%, ID/g). Detected by immunohistochemistry in 23 cases of HCC in the LHRH-positive rate was 82.61%, in the corresponding normal tissues, the positive rate was 15%; 20 cases of breast cancer positive rate of 95%, the corresponding normal tissues, the positive rate was 20%; 10 cases of prostate cancer positive rate of 70%, the corresponding normal tissues, the positive rate of 40%; 20 cases of lung cancer positive rate of 85%, the corresponding normal tissues, the positive rate of 15.79%; 20 cases of endometrial cancer positive rate of 80% in the corresponding normal tissues was 16.67% positive.99m Tc-LHRH mark was 97.9-100.0%, the radiochemical purity of 93.9-96.4%, marking the reaction gel content of <5%. Great product receptor marker analysis showed99m Tc-LHRH with saturable receptor binding characteristics and inhibition, and high affinity, RT = 23.2174 pmol, KD = 0.4348 nmol; intravenous injection of131 I-LHRH within 72 h after the mice rapidly cleared the blood radioactivity, the major radioactive accumulation in the liver and kidneys and by the liver, renal clearance, and other tissues and organs of the radioactivity gradually decreased with time. In conclusion, i) the liver, lung, breast, prostate, endometrial cancer exist in both LHRHR; ii)99m Tc-LHRH preparation is simple, rapid, radiochemical purity product obtained higher marks, better stability, no further purification; and iii) LHRH99m Tc labeled, still has a high receptor binding ability, biological activity; and has an ideal and realistic dynamics in animals, there is hope, as with the clinical value of imaging agent of GnRH receptors.