Expression And Significance Of TCTP Gene In Chronic Lymphocytic Leukemia

Objective:Translationally controlled tumor protein(TCTP)is a highly conserved category of protein which possesses pluripotent cellular functions.Overexpression of TCTPmRNA(Tm)has been proved in various malignant neoplasms.Previous studies indicated a negative feedback loop between p53 and TCTP.The aim of our present study was to explore the expression level of Tm in patients with chronic lymphocytic leukemia(CLL)and relevant prognostic significance.Methods:Between February 2008 and January 2015,147 previously untreated patients with CLL or patients who had not been treated for 6 months or more were enrolled in the present study.We tested the expression of Tm in the cohort and 15 examples of CD19+cells from healthy people as normal controls.Biological characteristics of the patients were analyzed to investigate the correlation between Tm expression and CLL prognostic factors.Results:Compared with normal controls,Tm expression level was obviously higher in 147 CLL samples(P<0.001).We found that the expression of Tm was associated positively with LDH(P=0.011).The group with p53 aberration(TP53 mutation and/or p53 deletion)showed higher expression(P<0.001).In multiple-factor analysis,only p53 aberration(P=0.005)were associated with overexpression of Tm.According to receiver operating characteristic(ROC)curve analysis for Tm expression based on p53 aberration(AUC,0.767;95%CI,0.678-0.856;P<0.001),optimal cut-off value of Tm was 1.10 with 75.9%sensitivity and 66.3%specificity.We divided the cohort of CLL into two groups based on the cut-off value and found significant difference(P=0.013)in overall survival(OS).In the 48 patients who received standard therapies including fludarabine,the Tm expressions of 23 fludarabine-resistance patients(refractory or relapsed in 24 months)were markedly higher than those 25 patients who achieved long-term remission(P<0.001).In addition,16 fludarabine-resistant patients without p53 aberration were still higher than those who achieved long-term remission(P=0.008).Conclusion:Our study has revealed the overexpression of Tm in CLL patients,which indicates the crucial significance of TCTP in the occurrence and development of CLL.Tm is also a potential indicator reflecting tumor burden and prognosis.Tm is upregulated in fludarabine-resistant patients and those with p53 aberration.Suppression of TCTP activity may be of potential value as a novel therapeutic strategy for chronic lymphocytic leukemia and even effective solution for resistant of fludarabine.Objective:Translationally controlled tumor protein(TCTP)is a highly conserved category of protein,which is proved overexpressed in various malignant neoplasm,including chronic lymphocytic leukemia(CLL).Expression of TCTP is correlated with prognosis of CLL.fludarabine,which is used as first-line chemotherapeutic medicine against CLL,can damage DNA chain and activate p53 and downstream pathways,consequentially induce the apoptosis of CLL cells.Previous study had proved the transcriptionally negative regulation of TCTP by p53.We stimulated CLL cells with fludarabine in vitro to upregulate p53 expression and explore the TCTPmRNA(Tm).Methods:Peripheral cells from 10 CLL patients were incubated in medium with 3.5?M fludarabine while isometric cells were incubated with medium only as blank control.After 48h-incubation,CLL cells were harvested to meansure apoptosis by staining with Annexin-V-FITC/propidium iodide(PI).Tm expression was quantified using real-time quantitative reverse polymerase chain reation(qRT-PCR).Fluorescence in situ hybridization(FISH)analysis was used to detect p53gene deletions.CLL cells were evaluated for p53 gene mutational status by PCR and sequencing.Expression of p53 protein was tested by Western Blot(WB).Statistical analysis was performed by software SPSS(version.19.0 windows)and a P value of 0.05 was considered significant.Results:Ten CLL patients consisted of 8 males and 2 females,whose medium age was 63(33-77)years old,Only 1 patient was in Binet A stage with 4 in stage B and 5 in stage C.P53 gene mutation and p53 gene deletion were found in 2 patient,who were labeled as aberrated group.Eight patient without p53 aberration were labeled as normal group.Before incubation apoptosis was 5.51%(5.31%-5.70%)in cells with p53 aberration and 4.93%(3.73%-21.37%)in the others.After 48h-intervene in vitro,apoptosis of cells without p53 aberration was 33.88%(27.32%-59.30%%)and 7.30%(4.40%-24.46%%)in control cells;apoptosis of aberrated cells was 13.40%(9.36%-17.43%%)in intervened group and 11.64%(9.68%-13.59%%)in control cells.No significant difference was found between normal group and aberrated group before incubation or after negative-control-incubation(P=0.62,P=0.74%),while obvious apoptosis was performed in normal group with fludarabine(P=0.02).P53 protein was markedly expressed and Tm was reduced(P=0.02)in CLL cells without p53 aberration after fludarabine intervention,while no similar variation occurred in aberrated group(P=0.31).Conclusion:Our study has revealed the overexpression of p53 protein in CLL cells after fludarabine stimulation,which induce the reduction of Tm and apoptosis.Resistance of fludarabine was obvious in CLL cells with p53 aberration.Overexpression of Tm in CLL could be prevented by activation of p53 gene.