Effects of CDC7 gene silencing and Rituximab on apoptosis in diffuse large B cell lymphoma cells.

BACKGROUND: The cell division cycle 7 (CDC7) is a serine-threonine kinase, which is required for DNA replication and is high expressed in diffuse large B cell lymphoma (DLBCL). METHODS: In this study, we targeted CDC7 in human DLBCL-ABC subtype cells (ly3) and examined the subsequent alterations in cellular apoptosis. The expression of CDC7 was silenced with small interfering RNA (siRNA)-expressing plasmid. CDC7 gene silencing cells were then incubated with or without rituximab for 24 h. Following treatment, Annexin V/propidium iodide staining followed by flow cytometry was used to examine cellular apoptosis. Furthermore, the expression of caspase 3, Bax, and Bcl-2 protein was analyzed by Western blotting. The expression of Bax and Bcl-2 mRNA was analyzed by quantitative real-time PCR. RESULTS: Compared to non-treated or control siRNA-transfected cells, significantly higher levels of apoptosis were detected in siCDC7-transfected cells and rituximab-treated cells (P < 0.05), which was further enhanced in CDC7-targeted cells with rituximab treatment (P < 0.05). The pro-apoptotic effects were accompanied with up-regulation of caspase 3 and Bax, meanwhile down-regulation of Bcl-2. CONCLUSION: Combined treatments using rituximab and CDC7 gene silencing significantly increases apoptosis in ly3 cells and plays synergistic effect. CDC7 is a novel therapeutic target in DLBCL patients. CDC7 inhibitors combined with rituximab will be the new therapy for the ABC-DLBCL patients.