Effect of cobalt-60 (γ radiation) on multidrug-resistant multiple myeloma cell lines

Cell Biol Int. 2011 Jul;35(7):721-5. doi: 10.1042/CBI20100061.


Emergence of resistance to chemotherapy and radiotherapy is a major obstacle for the successful treatment of MM (multiple myeloma). Prednisone, vincristine and melphalan are commonly used chemotherapeutic agents for the treatment of MM. In the current study, we examined the presence of possible cross-resistance between these drugs and gamma (γ) radiation. Prednisone, vincristine and melphalan resistant RPMI-8226 and U-266 MM cells were generated by stepwise increasing concentrations of the drugs. The sensitive and resistant cells were exposed to 200- and 800 cGy γ radiation, and proliferation was examined by XTT {2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide} assay. The results showed that Prednisone- and melphalan-resistant RPMI-8226 cells were also cross-resistant to 200 and 800 cGy γ radiation application, while vincristine-resistant cells did not show resistance. On the other hand, Prednisone-, vincristine- and melphalan-resistant U-266 cells showed cross-resistance to 200- and 800 cGy γ radiation application. These results demonstrated that MM cells resistant to anticancer agents respond to radiation in different levels. These findings may be important in the clinical applications of radiation therapy in the treatment of vincristine resistant MM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Cell Line, Tumor
  • Cell Proliferation* / drug effects
  • Cell Proliferation* / radiation effects
  • Cobalt Radioisotopes
  • Drug Resistance, Multiple* / drug effects
  • Drug Resistance, Multiple* / radiation effects
  • Drug Resistance, Neoplasm* / drug effects
  • Drug Resistance, Neoplasm* / radiation effects
  • Gamma Rays
  • Humans
  • Melphalan / pharmacology
  • Multiple Myeloma* / drug therapy
  • Multiple Myeloma* / pathology
  • Multiple Myeloma* / radiotherapy
  • Prednisone / pharmacology
  • Tetrazolium Salts / analysis
  • Vincristine / pharmacology


  • Antineoplastic Agents
  • Cobalt Radioisotopes
  • Tetrazolium Salts
  • 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide
  • Vincristine
  • Melphalan
  • Prednisone