ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of retinoblastoma-associated protein 46 (RbAp46) or RbAp 46 mRNA in bone marrow mononuclear cells (BMMNC) of acute leukemia (AL) patients and determine whether the expression is related to the classification and prognosis of ALs.</p><p><b>METHODS</b>The expression of RbAp46 protein in BMMNC was detected by Western blot in 46 AL patients and the expression of RbAp46 mRNA in BMMNC by semi-quantitative RT-PCR in 22 AL patients. The indirect immunofluorescence staining technique was applied to the localization of RbAp46 protein in BMMNC both in leukemia patients and control subjects.</p><p><b>RESULTS</b>(1) Both RbAp46 protein and mRNA were expressed in AL BMMNC and no significant difference was found among different leukemia types. (2) The expression of RbAp46 protein was lower in AL patients with high-degree tumor burden than in those with low-degree tumor burden (mean A, 93.4 +/- 37.2 vs 127.2 +/- 15.8, P < 0. 05). (3) The expression of RbAp46 protein was lower in refractory leukemia than those in non-refractory leukemia (mean A, 87.1 +/- 33.8 vs 126.6 +/- 21.2, P < 0. 05). (4) The expression of RbAp46 mRNA was lower in AL patients with high-degree tumor burden than in those with low-degree tumor burden (mean A R, 0.19 +/- 0.08 vs 0.31 +/- 0.12, P < 0. 05). (5) RbAp46 protein was mainly localized in nucleus of BMMNC in both AL patients and control subjects.</p><p><b>CONCLUSION</b>Both RbAp46 protein and mRNA are expressed in AL patients BMMNC. The downregulation of RbAp46 expression is associated with high leukemic burden and refractory to treatment. RbAp46 gene might be a tumor suppressor gene for leukemia.</p>