Expression And Significance Of P53,Rb And Their Pathways Correlated Genes P14ARF,p16INK4a And P33ING1b In Acute Myeloid Leukemia With T(8;21)

Object:In order to improve the diagnosis rate of acute myeloid leukemia with t(8;21), Morphologic, Immunologies Cytogenetic and Molecular biologic (MICM) classification were used; Through detecting the expression of p53, p14ARF, Rb, p16INK4a and p33INGlb genes in t (8; 21) AML, explore the correlation of these genes with the disease, and provide the clue for deeply investigating the pathogenesis of t(8;21) AML. Methods :Firstly we examined t(8;21) AML by Morphology, Immunology, Cytogenetic and Molecularbiology technology. Then, we regard t (8; 21) AML as studying subject, at the same time using acute myeloid leukemia without t (8; 21) and normal persons as controls. Polymerase chain react ion (PCR) was used to determine the deletion of p14ARF gene in 55 patients with AML, and the relative expression of pHARF mRNA was measured by semi-quantitative reverse transcript polymerase chain reaction (RT-PCR). Lastly, the expression of p53, p14ARF, Rb, p16INK4a and p33INGlb protein were studied by immunocytochemistry(ICC). Results:1. Of the 17 cases with t(8;21) AML, 14 cases were classified as M2, 2 as M3h, The remaining 1 case was uncertain,2. Cytogenetic analysis revealed 80%(12/15) cases of t(8;21) AML contained typical t(8;21) trans location.3. AML1-ETO fusion transcripts positive were found in all patients with t (8;21) chromosome, 3 cases without t (8;21) chromosome and 2 cases undetected by Cytogenetic analysis. AML1-ETO fusion transcripts were not detected in cases of t (8; 21) negative group.4. Higher expression of both CD19 and CD34 antigen in t (8; 21) AML patients were demonstrated by flow cytometry when compared to AML without t (8; 21), while the lower expression of CD33 was found in t (8; 21)+AML than t (8; 21) group (p<0. 05). Co-expression rate of CD19 with CD34 in t (8; 21) "AML (58. 8%) group was evidently higher than in negative control group (3. 6%) (p<0. 001).5. Total deletion rate of pHARF gene in AML was 9. 1%(5/55). Deletion of p14ARF gene occurred in 2 of 19(10.3%) patients with t (8; 21), and in 3 of 36(8.3%) cases without t (8; 21). Deletion of pHARF gene was not found in normal group. There was no statistical significance between these groups (p>0. 05).6. The relative expression of p14ARF mRNA in AML patients with t (8; 21) was nearly to normal persons (p>0. 05), while obviously lower than AML patients without t (8; 21) (p<0. 05). There was no evident difference in different FAB subtypes (p>0.05). Expressionof mutation type p53 in AML without t (8; 21) was dramatically higher than both in AML with t (8; 21) and normal person (p<0.01), while there was no difference between in t (8; 21)+ AML patients and normal persons (p>0. 05).7. Loss of Rb protein was found in 5 of 28 cases (17. 9%) without t (8; 21), and was not found in t (8; 21)+ AML and normal persons by ICC. There was no statistical difference in these three groups (p>0. 05) .8. Expression of p16INK4a protein in both AML with t(8;21) and without t(8;21) were lower than normal (p<0. 05), while there was no difference in these two AML groups (P>0.05). Among the different forms of AML, patients with M3 expressed abundant p16INK4a protein than cases with M2,M4 and M5(p<0.05). Co-loss of p14ARF mRNA with p16INK4a protein was found in 4 of 9 cases with t (8; 21)+AML.9.p33INGlb protein mainly localized in cellular nuclear .The nuclear expression of p33INGlb was no difference in t (8; 21) positive , t (8; 21) negative and normal groups (p>0. 05) .Decreased nuclear expression of p33INGlb was frequently associated with increased cytoplasmic expression of the protein. An inverse correlation was observed between p33INGlb nuclear and cytoplasmic labeling.Conclusion:1. AML patients with t(8;21) have distinct Morphologic, Cytogenetic, Immunologic and Mocleular biologic characteristics. Combination with M1CC classification can improve the diagnosis rateof t (8; 21) AMI. In these four methods, detection of AML1-ETO fusion transcripts plays a key role.2. p53 mutation, deleti...