Overexpression of the multidrug resistance gene product in adult rat hepatocytes during primary culture

Eur J Biochem. 1992 Apr 15;205(2):847-52. doi: 10.1111/j.1432-1033.1992.tb16849.x.


Expression of P-glycoprotein (P-gp), the product of multidrug resistance gene(s), was investigated in primary cultures of normal adult rat hepatocytes. Levels of P-gp mRNAs determined by Northern blotting and of P-gp measured by immunoblotting increased in parallel with time in culture. As in normal liver, P-gp was found to be localized on the membrane of bile canaliculus-like structures. This increased expression of P-gp was associated with decreased intracellular retention of doxorubicin, which could be restored by compounds such as verapamil and cyclosporin; doxorubicin (and also vincristine) was more cytotoxic to early than to late cultures. As in preneoplastic and neoplastic liver, overexpression of P-gp in cultured hepatocytes was associated with differential changes in drug-metabolizing enzymes, including increased glutathione S-transferase 7-7. Functional P-gp over-expression was observed in the absence of xenobiotic exposure or cell division; it could be linked to cellular stress occurring during cell isolation and plating. Increased expression of P-gp was blocked by actinomycin D, indicating its dependence on increased transcription, while cycloheximide led to a superinduction suggesting negative regulation by a protein factor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Amitriptyline / pharmacology
  • Animals
  • Blotting, Northern
  • Cell Membrane / metabolism
  • Cell Survival / drug effects
  • Cells, Cultured
  • Cyclosporine / pharmacology
  • Doxorubicin / metabolism*
  • Doxorubicin / pharmacology
  • Drug Resistance / genetics*
  • Gene Expression
  • Liver / cytology
  • Liver / drug effects
  • Liver / physiology*
  • Male
  • Membrane Glycoproteins / analysis
  • Membrane Glycoproteins / genetics*
  • Membrane Glycoproteins / metabolism
  • Nifedipine / pharmacology
  • Quinidine / pharmacology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Inbred Strains
  • Verapamil / pharmacology
  • Vincristine / pharmacology


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Membrane Glycoproteins
  • RNA, Messenger
  • Amitriptyline
  • Vincristine
  • Doxorubicin
  • Cyclosporine
  • Verapamil
  • Nifedipine
  • Quinidine