Experimental Study On Synergistic Interactions Of TRAIL And Chemotherapeutic Agents On Apoptosis Of Lymphoma Cell Lines Raji And Jurkat In Vitro

The Non-Hodgkin lymphomas (NHLs) are a diverse group of hematologic cancers which encompass any lymphoma other than Hodgkin lymphoma.Lymphoma is a type of cancer derived from lymphocytes, a type of white blood cell. Many subtypes of non-Hodgkin lymphoma have been described. Non-Hodgkin lymphomas are treated traditionally by combinations of chemotherapy, immunotherapy and radiation, et al.However, the function of these treatment is limited as well as side effect.Tumor necrosis factor-related apoptosis-inducing ligand(TRAIL) is a new member in the family of tumor necrosis factors. The death receptors belong to a subset of tumor necrosis factor receptor superfamily members and include Fas (CD95), tumor necrosis factor receptor (TNFR)-1, death receptor 3 (DR3/wsl-1), death receptor 4 (DR4, TRAIL-R1), and death receptor 5 (DR5, TRAIL-R2). The respective ligands bind to these receptors causing trimerization of the receptors and apoptosis. Two of these receptors, DR4 and DR5, have aroused considerable interest and research because of their potential for the treatment of the hematological malignancies. This is due to the observation that combination of TRAIL and DR4 or DR5 selectively can induce apoptosis in tumor cells. There are two major pathways for apoptosis, the mitochondrial or intrinsic apoptotic pathway and the death receptor or extrinsic apoptotic pathway. The intrinsic apoptotic pathway is typically initiated by DNA damage, which causes the upregulation of p53, an increase in the bax:bcl-2 ratio, and the release of cytochrome c from between the inner and outer mitochondrial membranes into the cytosol. Cytochrome c binds to and activates apoptosis-activating factor-1 (Apaf-1) in the cytosol in a process that requires deoxyadenosine triphosphate (dATP), and both caspase 9 and 3 are subsequently activated with the induction of apoptosis. The extrinsic apoptotic pathway is triggered by binding of the death receptor ligands to their cognate receptors. The death receptors for TRAIL, DR4 and DR5, contain cysteine rich repeats in the extracellular domain that bind to TRAIL causing receptor trimerization and subsequent apoptosis. Therefore, TRAIL is promising in treating the hematological malignancies including NHL. However, resistance to TRAIL in tumor cells have blocked its usage in clinical work. Studies have been done to value the combination of TRAIL with chemotheray and to explore the mechanism of TRAIL-resistance.Cis-platinum complexes is a platinum-based chemotherapy drug used to treat various types of cancers, including sarcomas, some carcinomas (e.g. small cell lung cancer, and ovarian cancer), lymphomas and germ cell tumors. It was the first member of its class, which now also includes carboplatin and oxaliplatin. Platinum complexes are formed in cells, which bind and cause crosslinking of DNA; ultimately triggering apoptosis. Combination of cisplatinum with TRAIL have been proved to be useful to treat some tumors, such as cervical carcinoma, laryngocarcinoma, and so on. Given all the above, in order to investigate the synergistic molecular mechanism of Cisplatin enhancing the TRAIL-induced apoptosis of lymphoma Raji and Jurkat cell lines and provide a novel treatment model of the TRAIL in lymphoma, we design this study. The human lymphoma cell line Raji and Jurkat was treated with Cisplatin, TRAIL, respectively, or in combination. The cytotoxic effect and the rate of apoptosis were determined by MTT and flow cytometry,respectively; the expression of cyclin E(317bp)CDK2(546bp)and p27(237bp)mRNA was determined by reverse transcription-polymerase chain reaction (RT-PCR); and the expression of signal transduetion proteins,such as Caspase-3,NF-κB and Survivin Was detected by Western blot.We get the results that combination with subcytotoxic dose of Cisplatin could reverse the sensitivity of raji and jurkat cells to TRAIL-induced apoptosis,and could down·regulate the expression of cyclin E,CDK2 and survivin, NF-κB; up·regulate the expression of Caspase3 and p27.In conclusion, Cisplatin could sensitize raji and jurkat cells to TRAIL-induced apoptosis.