An in vitro model to study chemoresistance in non-Hodgkin's lymphoma patients over-expressing mutant p53

J Pharmacol Toxicol Methods. Mar-Apr 2007;55(2):151-8. doi: 10.1016/j.vascn.2006.05.008. Epub 2006 May 27.


Introduction: P-Glycoprotein plays a major role in regulating the concentration of chemotherapeutic agents inside the cytoplasm of normal and cancerous cells. The present in vitro study has primarily focused on the evaluation of the chemosensitising drug model, verapamil, as a P-glycoprotein antagonist not only to overcome chemoresistance in non-Hodgkin's lymphoma (NHL) chemoresistant cells (p53(+) i.e. over-expressing p53 mutant protein NHL cells) but also to evaluate and suggest the use of the single cell gel electrophoresis (SCGE) assay in the clinical setting.

Methods: Leucocytes from CHOP-chemoresistant NHL patients (p53(+) cells) were examined in the SCGE assay. Altered levels of DNA damage (tail moments) were determined by the assay not only in the leucocytes from clinical samples, but also in the Raji cell sub-lines (NHL model) which are also over-expressing p53 mutant protein. In addition, as a comparison, P-glycoprotein was examined in normal human leucocytes and Raji cells.

Results: Verapamil increased the tail moments induced by doxorubicin in all cell types over-expressing p53 mutant protein.

Discussion: The assay was successful for evaluating P-glycoprotein regulation. This suggests the applicability at the cellular level of the method as suitable for use in the clinical setting since it is reliable and could be used pre-clinically or perhaps instead of or alongside clinical trails. Cells from patients with a chemoresistant disease state or whose disease relapses subsequently could be treated with such novel experimental therapies in vitro to determine the necessity for the individual administration of a P-glycoprotein antagonist.

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / antagonists & inhibitors
  • ATP Binding Cassette Transporter, Subfamily B, Member 1 / metabolism
  • Adolescent
  • Aged
  • Aged, 80 and over
  • Antineoplastic Combined Chemotherapy Protocols / pharmacology
  • Caco-2 Cells
  • Comet Assay / methods*
  • Cyclophosphamide / pharmacology
  • DNA Damage
  • Doxorubicin / pharmacology
  • Drug Resistance, Neoplasm / drug effects
  • Drug Resistance, Neoplasm / genetics*
  • Female
  • Fluorouracil / pharmacology
  • Gene Expression Regulation, Neoplastic* / drug effects
  • Humans
  • Leukocytes / metabolism
  • Lymphoma, Non-Hodgkin / drug therapy
  • Lymphoma, Non-Hodgkin / genetics*
  • Lymphoma, Non-Hodgkin / metabolism
  • Male
  • Mutation
  • Prednisone / pharmacology
  • Tumor Suppressor Protein p53 / genetics*
  • Tumor Suppressor Protein p53 / metabolism
  • Verapamil / pharmacology
  • Vincristine / pharmacology


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Tumor Suppressor Protein p53
  • Vincristine
  • Doxorubicin
  • Cyclophosphamide
  • Verapamil
  • Fluorouracil
  • Prednisone

Supplementary concepts

  • CHOP protocol