Synergistic Lethal Effects Between Gemcitabine and Arsenic Trioxide on Non-Hodgkin Lymphoma Cell Lines Is Associated with Modulation of PI3K/Akt Signaling Pathway

OBJECTIVE: To explore the synersistic lethal effects of gemcitabine(GEM) with arsenic trioxide(ATO) on proliferation and apoptosis in the non-Hodgkin lymphoma cells ,and the major molecular signaling pathway involved in these effects.

METHODS: Human non-Hodgkin lymphoma cell lines Jurkat and Raji were used to determine the effects of GEM and ATO (alone or in combination) in vitro, as well as the PBMCs.Cell proliferation was measured by CCK-8 analysis. Cell cycle distribution and apoptosis were monitored by flow cytometry. The self-renewal and proliferating ability of cells were examined by methylcellblose conlony-forming units(CFU)assay.The activation of casepase-3, Bcl-2, and Akt was assessed by Western blot analysis.

RESULTS: ATO and GEM inhibited cell viability in a dose- and time-dependent manner, and induced cell cycle arrest and apoptosis.

The combination of ATO and GEM displays a synergistic or at least additive antitumor activity in vitro against cells than each single treatment. An obvious inhibition of NHL cells proliferation and an increased population of cells in apoptosis were observed in the combination treatment group, but not on PBMCs. ATO combined GEM at IC20 concentration did caused 50% inhibition of NHL cells proliferation. Afterwards, the rest of NHL cells were strongerly arrested in G0/G1 stage by ATO and GEM than each single treatment. Additionally, combination treatment also significantly reduced the ability of colony formation in NHL cells than treatment with either agent alone. Moreover, ATO blocked the Akt signaling pathway, subsequently inhibited Bcl-2 expression, reactivated cleaved caspase-3, while GEM did not. The combination group augmented these effects than each single agent.

CONCLUSIONS: ATO and GEM might be a potential candidate of the combination therapy for treatinghumanrefractory and relapsed malignant lymphoma, which also might be a salvage approach for patients who will be autologous transplantation in clinical trials; these effects were apparently associated with the modulation of PI3K/Akt signaling pathway.