Effects Of Ligation Of CD₄₀ On The Biological Behavior Of Malignant Hematopoiesis Cells And Their Molecular Mechanism

Objective: CD40, a member of the tumor necrosis factor (TNF)/nerve growth factor (NGF) superfamily has been demonstrated to be expressed at high levels on a variety of human carcinoma cells . Ligation of CD40 on different carcinoma cells was found to have a variety of the biological behavior, but little was known concerning its mechanism. We studied the biological effects mediated by soluble recombinant human CD40 ligand (srhCD40L) on malignant hematogencus cell line Ca46,K562,HL60 cells.We also explored the molecular mechanism of the biological effects mediated Ligation of CD40 by srhCD40L on human Burkitt's lymphoma CA46 cells,and evaluated the expression of CD40 in acute myeloid leukemia (AML).Metheds: By using Trypan blue exclusion, MTT assay, cell cycle, cell apoptosis (Annexin-V-FITC,TUNEL), the biological effects mediated Ligation of CD40 by srhCD40L on malignant hematogencus cell line Ca46,K562,HL60 cells were studied. By using semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and western blotting, we studied the molecular mechanism ( gene of bax,bcl-XL,survivin,pten and protein of Survivin) of the biological effects mediated Ligation of CD40 by srhCD40L on human Burkitt's lymphoma CA46 cells. And by using flow cytometry (FCM), CD40 of AML cells was studied in 48 AML cases. Results: High expression levels of CD40 were detected on CA46, K562 cells ,but no on HL60 cells.The mean fluorescence intensity (MFI) on CA46 was more than those of K562 (P<0.05). Ligation of CD40 by srhCD40L gave rise to a typical homo-type cell aggregation of CA46,K562 cells and resulted in cells growth inhibition of CA46,K562 and apoptosis ,but no effect of HL60 cells. On CA46 cells mediated Ligation of CD40 by srhCD40L ,the expressions of survivin mRNA and protein down-requlated and pten mRNA up-regulated. Out of 48 AML cases, 25 cases(52.08%)showed positive expression of CD40.The incidences of splenomegaly,thrombocytopenia and hyperleukocytosis in CD40+ AML cases was significantly higher than those in CD40-ones.Conclusion: Ligation of CD40 by srhCD40L inhibits malignant hematogenous cells proliferation and induces their apoptosis. This might be associated with the expression of CD40.Survivin mRNA and protein ,and pten mRNA might be related to cell growth inhibition of CA46 and to apoptosis mediated Ligation of CD40 by srhCD40L. The expression of CD40 might be associated with some unfavorable clinical features of AML.