The Study Of Expression And Mechanism Of CDC7&MCM2 In Diffuse Large B Cell Lymphoma

BackgroundMalignant lymphoma is a common kind of cancer in China.Diffuse large B cell lymphoma(DLBCL)is the most common subtype in malignant lymphoma.Chemotherapy is the primary means to treat malignant lymphoma.Most patients with DLBCL treated with standard chemotherapy regimen can receive response,but 25?30%patients are resistant to chemotherapy.This kind of resistant lymphoma belongs to refractory lymphoma,such as ABC-DLBCL,which is still difficult to treat nowadays.CDC7 is a serine/threonine kinase that is essential for the initiation of eukaryotic DNA replication through phosphorylating Mem proteins.The studys about the relationship between CDC7&MCMs and malignant lymphoma were reported constantly,but the outcomes have not shown the consistent conclusions.CDC7 is high expressed in many kinds of human tumor cells including DLBCL.Whether the expression of CDC7 is related with drug resistance of ABC-DLBCL?Whether inhibiting CDC7 expression can improve the response rate of ABC-DLBCL patients?Whether inhibiting CDC7 expression with rituximab can prolong the overall survival of ABC-DLBCL?These questions need to be explored.Objective1.To study the relationship between CDC7.MCM2 and prognosis of patients withDLBCL.2.To study the relationship between CDC7.MCM2 and traditional prognosticfactors of patients with DLBCL.3.To confirm the drug resistance mechanism of ABC-DLBCL mediated by CDC7.4.To confirm the effect of CDC7 inhibition with rituximab in the apoptosis ofABC-DLBCL in order to explore new therapy in the treatment of ABC-DLBCL.Methods1.Clinical trial:Treatment-naive patients with DLBCL in Tianjin Medical University Cancer Hospital from January 2008 to January 2010 were enrolled into this study.We collected the peripheral blood?tissue?bone marrow of DLBCL patients.The expression level of CDC7&MCM2 were examined by immunohistochemistry and RT-PCR to clarify the relationship between CDC7&MCM2 and prognosis of DLBCL patients.2.Basic research:ABC.GCB-DLBCL cells were cultured in vitro.The expression level of CDC7 was examined by Western-blotting.CDC7 was down-regulated by shRNA,then co-cultured with rituximab,the effect of inducing apoptosis was detected to find the related mechanism of resistance in ABC-DLBCL.The down-stream factors were examind in order to find the mechanism of apoptosis mediated by CDC7 inhibition and rituximab.Results1.The expression level of CDC7&MCM2 was poor prognostic factor of DLBCL patients.2.The expression level of CDC7&MCM2 was positively correlated with IPI score and Ann Arbor stage,CDC7&MCM2 in addition with IPI score and Ann Arbor stage can be the particular prognostic factors for DLBCL patients.3.The expression level of CDC7&MCM2 in peripheral blood was positively correlated with tissue and bone marrow.We can examined peripheral blood of patients to replace other samples.4.Inhibition of CDC7 can induce apoptosis of ABC-DLBCL cells through down-regulating Bcl-2 meanwhile up-regulating bax.CDC7 inhibition with rituximab has synergistic effect in apoptosis of ABC-DLBCL cells.Conclusions1.The expression level of CDC7&MCM2 in addition with IPI score and Ann Arbor stage can be the particular prognostic factors for DLBCL patients.Based on the particular prognostic factors,we can find more individual regimen in order to prolong overall survival of DLBCL patients.2.CDC7 mediated the drug resistance of ABC-DLBCL.CDC7 is the new target for ABC-DLBCL patients.CDC7 inhibition with rituximab can prolong the overall survival of ABC-DLBCL patients.