Expression And Clinical Significance Of Livin, Smac And PRND In Leukemia

Objectives: Livin is a novel member of inhibitor of apoptosis proteins(IAPs)family, which contains a baculoviral inhibitory repeat (BIR) domain and a zinc-binding domain, and it inhibits apoptosis through the neutralization of Smac and the inhibition of caspase-3,caspase-7 and caspase-9. Livin is expressed in some tumors, and its high expression associates with poor prognosis. The expression and significance of Livin in leukemia remains to be elucidated. Smac (second mitochodria-derived activator of caspase, Smac) is a proapoptosis protein releasing from mitochondrion, which induces cell apoptosis by antagonizing the inhibition of IAP. Doppel protein (downstream prion protein-like, Dpl) is a novel PrP(prion protein)-like protein, which is expressed in reproductive system and some tumors. PRND gene encodes for Doppel protein, and its clinical research is very limited. This study intended to investigate the expression and clinical significance of livin, Smac and PRND in leukemia.Methods: The expression of Livin, Smac and PRND mRNA were measured in bone marrow cells or peripheral blood cells from 91 adult patients with acute leukemia (50 de novo acute leukemia patients, 10 relapsed patients and 31 continued complete remission patients) and 17 patients with chronic granulocytic leukemia by semi-quantity reverse transcription polymers chain reaction (RT-PCR). 21 healthy samples were selected as normal controls (NC).Results1 Expression of Livin mRNA1.1 Expression of Livin mRNA in patients with acute leukemiaThe positive rate of Livin mRNA in newly diagnosed AL patients was 84%(42/50), and the expression level ranged from 0 to 2.473 with an average level 0.485. The positive rate of Livin mRNA in normal controls (NC) was 42.9%(9/21), and the expression level ranged from 0 to 0.285 with an average level 0.073.The level of Livin mRNA in patients with newly diagnosed acute leukemia (AL) was significantly higher than that of normal controls (P<0.05). The Livin level in relapsed patients (positive rate 100.0%, range 0.075-1.256, average 0.536) was higher than that of normal controls(P<0.05),there was no difference between newly diagnosed acute leukemia (AL) patients and relapsed patients(P>0.05) . The livin expession of patients in continued complete remission (positive rate 51.6%, range 0-0.782, average 0.211) was lower than AL group and relapsed patients (P<0.05). And the Livin level of patients in continued complete remission was higher than that of NC group with no statistical significance (P>0.05).The positive rate of Livin mRNA in acute myelogenous leukemia(AML) was 82.5%(33/40), and the expression level ranged from 0 to 2.473 with an average level 0.446. The positive rate of Livin mRNA in acute lymphocytic leukemia(ALL) was 90%(9/10), and the expression level ranged from 0 to 2.209 with an average level 0.639. The level of Livin mRNA in acute lymphocytic leukemia(ALL)was higher than that of acute myelogenous leukemia(AML) without statistical significance (P>0.05).The expression of livin in the two groups were both higher than that in normal controls (both P<0.05).In FAB classification, the differences of expression levels of Livin mRNA among M2,M3,M4,M5 and M6 had no statistical significance(P>0.05). Livin expression level in M4 group was relatively higher than in other groups without statistical significance (P>0.05).1.2 Expression of Livin mRNA in patients with chronic myeloid leukemiaThe positive rate of Livin mRNA in patients with chronic myeloid leukemia-chronic phase(CML-CP)was 81.8%(9/11), and the expression level ranged from 0 to 0.552 with an average level 0.224. The positive rate of Livin mRNA in normal controls(NC) was 42.9%(9/21),and the expression level ranged from 0 to 0.285 with an average level 0.073. The level of Livin mRNA in CP group was significantly higher than that in normal controls (P<0.05). The expression of Livin in CML-AP/BP (positive rate 83.3%, range 0-0.768, average 0.288) was higher than that of NC (P<0.05). The expression level of Livin mRNA in CML-AP/BP was higher than that in CML-CP,but the difference had no statistical significance (P>0.05).2 Expression of Smac mRNA2.1 Expression of Smac mRNA in acute leukemia patientsSmac mRNA was detected in 35 samples of 50 newly diagnosed AL patients. The positive rate of Smac mRNA in AL patients was 70.0 %(35/50), and the expression level ranged from 0 to 1.564 with an average level 0.503.The Smac mRNA expression level in AL was significantly higher than in normal controls (positive rate 23.8%, range 0-0.460, average 0.056)(P<0.05). The Smac mRNA expression level in relapsed patients (positive rate 70%, range 0-1.378, average 0.560) was higher than that in normal controls (P<0.05), but had no significant difference compared with AL group (P>0.05). Smac mRNA expression in patients in continued complete remission (CCR) (positive rate 32.3%, range 0-1.232,average 0.250) was significantly lower than in AL group, but had no significant difference compared with normal controls (P>0.05).The positive rate of Smac mRNA in acute myelogenous leukemia (AML) is 70.0%(28/40), and the expression level ranged from 0 to 1.564 with an average level 0.503. The Smac level in AML was higher than that of ALL group (positive rate 70.0%, range 0-0.996, average 0.502) without stastifical difference (P>0.05). They were both significantly higher than that of NC group (both P<0.05).In FAB classification, the difference of expression level of Smac mRNA in M2,M3,M4,M5 and M6 had no statistical significance (P>0.05).Smac mRNA expression level in M3 group was relatively higher than other groups without stastifical significance (P>0.05).2.2 Expression of Smac mRNA in chronic myeloid leukemia patientsThe expressin of Smac in CML-CP (positive rate 45.5%, range 0-0.997, average 0.299) was significantly higher than in NC group (P<0.05). The expression of Smac in CML-AP/BP (positive rate 66.7%, range 0-1.392, average 0.571) was higher than that in CML-CP .The difference between CML-CP and CML-AP/BP had no statistical significance (P>0.05). But the expression level of Smac mRNA in CML-AP/BP was significantly higher than that of NC group (P<0.05).3 Expression of PRND mRNA3.1 Expression of PRND mRNA in acute leukemia patientsThe positive rate of PRND mRNA in newly diagnosed AL patients was 88.0%(44/50), and the expression level ranged from 0.000 to 2.306 with an average level 0.387. PRND mRNA expession in AL group was significantly higher than that in normal controls (positive rate 57.1%, range 0-0.336, average 0.070)(P<0.05). The PRND mRNA expression level in relapsed patients (positive rate 90%, range 0-1.262, average 0.526) was significantly higher than that in normal controls (P<0.05), but had no significant difference compared with AL group (P>0.05). The positive rate of PRND mRNA in continued complete remission (CCR) patients was 77.4%(24/31). The PRND expression level in CCR group (range 0-1.213, average 0.341) was still higher than in NC group (P<0.05), it was lower than that of newly diagnosed AL group with no statistical significance (P>0.05).The positive rate of PRND mRNA in AML was 87.5%(35/40). The expression level ranged from 0 to 2.306 with an average level 0.356. The PRND level in AML was lower than that of ALL group (positive rate 90.0%, range 0-0.925, average 0.512) without stastifical difference (P>0.05). The PRND expression in AML and ALL were both significantly higher than that of NC group (both P<0.05).In FAB classification, the difference of expression level of PRND mRNA among M2,M3,M4,M5 and M6 had no statistical significance (P>0.05). PRND mRNA expression level in M2 group was relatively higher than other groups without statistical significance (P>0.05).3.2 Expression of PRND mRNA in chronic myeloid leukemia patientsThe expressin of PRND mRNA in CML-CP (positive rate 90.9%, range 0-1.033, average 0.276) was significantly higher than in NC group (P<0.05). The expression of PRND in CML-AP/BP (positive rate 100.0%, range 0.084-1.445, average 0.352) was higher than that in CML-CP. The differences between CML-CP and CML-AP/BP had no statistical significance (P>0.05). But the expression level of PRND in CML-AP/BP was significantly higher than that of NC group (P<0.05).4 The relationship between the expression of Livin,Smac and PRND mRNA and clinical effect (CR rate) in newly diagnosed acute leukemia patientsThe therapeutic efficacy in 44 of 50 newly diagnosed acute leukemia patients was evaluated (1 patient died early, 5patients gave up treatment).17 of 37 Livin+ AL patients achieved complete hematological response (CR) after induction therapy with a CR rate of 45.95%. All the 7 Livin- AL patients achieved CR with a CR rate of 100.00%. The CR rate in Livin- AL was significantly higher than in Livin+ AL group (χ2=4.928, P<0.05). 83.33%(10/12) of Smac- AL patients achieved CR, only 43.75%(14/32) of Smac+ AL patients achieved CR. The CR rate of Smac-AL group is higher than that of Smac+ group (χ2=5.515, P<0.05).The CR rate of Livin-Smac- group (100%, 7/7) was higher than that of Livin+Smac+ (43.75%, 14/32)(P<0.05). 3 of 5 Livin+Smac- AL patients achieved CR with a CR rate of 60.0%, and its CR rate was lower than that of Livin-Smac- group with no statistical significance (P>0.05). The difference of CR rate between Livin+Smac- group and Livin+Smac+ group had no statistical significance (P>0.05).20 of 40 PRND+ AL patients achieved complete hematological response after induction therapy with a CR rate of 50%(20/40). All the 4 PRND- AL patients achieved CR with a CR rate of 100.00%. The CR rate of PRND- AL group was higher than that of PRND+ group with no statistical significance (χ2=1.927,P>0.05).In 10 relapsed cases, only 2 cases achieved complete hematological response (CR). The remaining 8 cases (including 5 Livin+Smac+PRND+ cases, 2 Livin+Smac-PRND+ cases and 1 Livin+Smac+PRND- case) didn't achieved complete hematological response (CR).5 Correlation analysis indicates that the level of Livin was positively correlated with Smac in newly diagnosed leukemia patients (r=0.545, P<0.05).Conclusions1 The level of Livin mRNA in newly diagnosed acute leukemia patients was significantly higher than that of normal controls. The level of relapsed patients was higher than that of normal controls. The CR rate of Livin- group was higher than that of Livin+ cases, indicating that Livin may be involved in the pathogenesis and progression in AL. Overexpression of Livin mRNA predicts poor prognosis.2 The level of Smac mRNA in newly diagnosed acute leukemia patients was also significantly higher than that of normal controls. The high expression of Smac mRNA was associated with high expession of Livin, suggesting that Smac performs its proapoptotic action through antagonism of the antiapoptotic effect of Livin. 3 The levels of PRND mRNA in newly diagnosed acute leukemia patients,continued complete remission patients and relapsed patients were all significantly higher than that of normal controls, indicating that the high expression of PRND may be involved in the pathogenesis of leukemia ,but the mechanism remains to be further studied.4 There was a positive correlation beween Livin expession and Smac expression in newly diagnosed leukemia.5 The level of Livin,Smac and PRND mRNA in chronic myeloid leukemia chronic phase,accelerated phase and blastic phase was significantly higher than that of normal controls (both P<0.05).