Background  Multiple myeloma (MM) is the second most common hematological malignancy. Introduction of several new classes of drugs for MM treatment has increased response rates and survival substantially, but MM also remains incurable and new therapies are needed to induce more profound clinical outcomes.

  Objective  To investigate the synergistic anti-tumor effect between the mammalian target of Rapamycin inhibitor Rapamycin (Rapa) and glycolysis inhibitor 2-deoxy-D-glucose (2-DG) on the human MM RPMI8226 cells.

  Methods  CCK-8 was used to analyze the effects of the two drugs alone and in combination on the proliferation and toxicity of human myeloma RPMI8226 cells, and the combination index (CI) was calculated by CompuSyn software; Cell cycle and apoptosis were detected by the flow cytometry; Western blot was used to detect the expression of cell cycle regulation molecules CyclinD1, apoptosis-related indicators p53, Bax and Bcl-2.

  Results  The CCK-8 method showed that Rapa combining with 2-DG had significant anti-myeloma synergistic effect under various combinations of different concentrations after 48 h treatment, with the CI value of 0.6-0.8, among which the CI value of Rapa (50 nmol/L) and 2-DG (0.5 mmol/L) was 0.642, showing a good synergistic effect. Flow cytometry showed that cell cycle was arrested in the G0/G1 phrase, S phase decreased, while the apoptosis rate significantly increased compared with the control group and single drug group after combined application of Rapa (50nmol/L) and 2-DG (0.5nmol/L) (all P＜0.05). Western blot showed that the expression of pro-apoptotic indicators p53 and Bax increased, and the anti-apoptotic protein Bcl-2 decreased in the combination group (all P＜0.05).

  Conclusion  The combined application of Rapa and 2-DG shows a good synergistic effect by inhibiting the proliferation of RPMI8226 cells, blocking cell cycle and increasing apoptosis, which brings enlightenment for further exploration of the usage of Rapa and 2-DG in multiple myeloma.