Researches for the Effects and Mechanisms of Recombinant Human Erythropoietin Administrated in BALB/c Murine Models with Multiple Myeloma.

Multiple myeloma myeloma accounts for approximately 1 percent of all cancers and 10 percent of hematologic cancers. It is incurable with conventional chemotherapy. Recent studies suggest that rHuEpo has additional biological effects which significantly prolonged the expected survival of six end-stage multiple myeloma (MM) patients and led to hypothesize that Epo might have an anti-neoplastic or anti-myeloma effect. This latter observation was further supported by studies.

Based on the myeloma models which established in BALB/c murine with MPC-11 myeloma cell line, our study is to verify the true effects, to research the suitable dose and administration way of recombinant human erythropietin(rHuEPO) for individuals with MM, as well as the possible antitumor mechanism in BALB/c murine myeloma models.

550 healthful BALB/c mice were injected s.c. with 6×10⁵ MPC-11 cells to establish the multiple myeloma models. When small palpable tumors were observed, the tumor-bearing mice were randomizedly divided into five groups which were respectively administrated the various rHuEPO doses (10,20,30,40 and 50 units per injection) and a placebo group with the saline. In the study, rHuEPO treatment was strated in 5 days after the initial MPC-11 cells injection, daily s.c. injections of rHuEPO for 30 consecutive days, followed by one injection per week for 4 weeks with a same dose as before. Hemoglobin, serum IL-6 and TNF-α were monitored before the start of rHuEPO administration and in 15 days, 30 days and 60 days after the start of rHuEPO administration. Immunofixation electrophoresis(IFE) was performed to detect the existence of the serum monoclonal immunoglobulin before the rHuEPO treatment and in 60 days after the rHuEPO-treatment. In the second part of the study, microvessel density(MVD) and TdT-mediated dUTP nick end labeling (TUNEL) techniques were performed to evaluate the tumor proliferation burden and tumor cell apoptosis respectively. Tumor volume change was monitored twice a week and weight change of tumour-bearing mice was measured once a week for every individual mouse during the whole study.

The serum monoclonal immunoglobulin appeared in 12 days after the initial MPC-11 cells injection. There wasn't a significant decrease in tumor size of bearing cancer mice after administration of rHuEPO, and there was no significant difference among each dosage group. rHuEPO can obviously increase Hb levels in bearing cancer mice. The mice with a smaller tumor size had a higher Hb level, which resulting in a longer survival. Individual survival showed a significant positive correlation with Hb level (Spearman's rho 0.821, p=0.000), and in contrast, it had a negative correlation with tumor size (Spearman's rho  0.475, p=0.009). The serum levels of IL-6 showed no significant differences between the each rHuEPO treatment group and the placebo group, and the result was the same in the serum levels of TNF-α. Also, there is no difference in MVD between the treatment groups and placebo group. The apoptotic index of the treatment groups with rHuEPO seemed a little higher than that of the placebo group.

rHuEPO administration to the tumor-bearing mice seemed to prolong their individual survival. Insufficient evidence was found for the anti-MM therapeutic role of rHuEPO in our study.

No relevant conflicts of interest to declare.