Effect of erythropoietin, 5-fluorouracil and SN-38 on the growth of DLD-1 cells.

Supplementation of recombinant human erythropoietin (rHuEpo) is one of the methods for the treatment of anemia. The influence of rHuEpo on proliferation or clonogenic growth of cancer cells is not clear and some of the published results are conflicting. The aim of this work was to study the effect of rHuEpo on colon cancer cells when given alone or in combination with cytostatics. Human colon adenocarcinoma cells (DLD-1) were cultured in medium with rHuEpo, 5-fluorouracil (5-FU) and an active metabolite of irinotecan (SN-38). Cell viability was determined using a hematocytometer and 0.4% (w/v) trypan blue dye. Cell proliferation was measured by the MTT assay. Expression of EpoR, Bax, Bcl-2 and Akt1 protein was assessed by Western blot. The results of this study indicate a dose-dependent inhibitory effect of rHuEpo on DLD-1 cell growth and proliferation. Moreover, the combined treatment of rHuEpo and cytotoxic agents such as 5-FU and SN-38 increases the antitumor action, which is indicated by decreases in proliferation in the MTT test, cell numbers and DNA synthesis. We found a significant increase in EpoR, Bcl-2 and Akt1 protein expression in all cells grown in medium containing 3 IU of rHuEpo. We observed that EpoR is constitutively expressed in DLD-1 cells. Our results indicate that rHuEpo acts via EpoR to directly inhibit DLD-1 cell growth and indirectly modulate the cytostatics effects of 5-FU and SN-38.