ABSTRACT
OBJECTIVE: To investigate the relationship between the uptake of technetium-99m methoxyisobutyl isonitrile ((99m)Tc-MIBI) and the expression of multidrug resistance genes mdr-1 and MRP in lung cancer so as to guide chemotherapy. METHODS: Eighteen lung cancer patients were given 1 110 MBq(99m)Tc-MIBI intravenously. Chest single-photon emission-computed tomography was performed 60 and 120 min after the injection. The early and delay uptake rates and retain index of (99m)Tc-MIBI were calculated by the count ratio of the lung lesion to contralateral normal lung tissue. The expressions of mdr-1 and MRP genes in specimens of lung cancer and normal lung tissues near the cancers resected during operation among the 27 patients were detected with RT-PCR method. RESULTS: The positive rate of (99m)Tc-MIBI in the chest of lung cancer patients was 83.3% (15/18). The early uptake ratio of imaging in lung cancer patients was 1.99 +/- 0.64. After time decay correction, the rate of target to background and the retain index in 13 delay imagings were 2.06 +/- 0.69 and -45% approximately 33% respectively. In specimens of lung cancer, the positive expression rates of mdr-1 and MRP were 22.2%(6/27) and 63%(17/27) with the expression amount of 0.39 +/- 0.1 and 0.23 +/- 0.17 respectively. In specimens of normal lung tissues near lung cancer, the positive expression rates of mdr-1 and MRP genes were 35%(7/20) and 45.0%(9/20) with the expression amount of 0.44 +/- 0.14 and 0.17 +/- 0.18 respectively. In lung cancer tissues, the positive rate of MRP was higher than that of mdr-1 (P < 0.05), however, in the tissues near lung cancer, no significant difference was found between the positive rate of MRP and that of mdr-1 (P >< 0.05). There was no marked correlation (P >< 0.05) among the co-expression or expression of mdr-1 and/or MRP and the early uptake or retain index in lung cancer. CONCLUSION: The primary chemoresistance of lung cancer has not significant correlation to the expression of multidrug resistance genes mdr-1 and MRP. Other resistance mechanism may exist. (99m)Tc-MIBI imaging has not much clinical value in predicting the expression of mdr-1 and MRP genes.
