Development of a syngeneic in vivo tumor model and its use in evaluating a novel P-glycoprotein modulator, PGP-4008.

Abstract

Multidrug resistance (MDR) is a phenomenon by which tumor cells develop reduced sensitivity to anticancer drugs, which often leads to the failure of cancer chemotherapy. A prominent mechanism of MDR is the overexpression of the multidrug efflux pump, P-glycoprotein (P-gp), that decreases the intracellular accumulation of many anticancer drugs, leading to increased tumor growth. Intensive efforts are under way to develop clinically useful MDR modulators that inhibit the function of P-gp for use in combination with established anticancer drugs. Our goal was to develop an improved in vivo solid tumor model utilizing immunocompetent animals to examine the efficacy of P-gp-specific MDR modulators. Using in vitro cytotoxicity and drug accumulation assays, two transformed murine cell lines, JC and TIB-75, were found to demonstrate the P-gp-mediated MDR phenotype. In contrast, two similar lines did not express functional P-gp. Western blot analyses confirmed the expression of P-gp and the lack of expression of the closely related drug efflux protein MRP1 in the JC and TIB-75 cell lines. The JC cell line displayed excellent tumorigenicity and consistent growth kinetics when implanted into immune-competent Balb/c mice. Animals treated with a combination of a known MDR modulator, cyclosporin A, and a cytotoxic drug, doxorubicin, exhibited significantly reduced tumor growth compared with untreated controls or animals treated with either cyclosporin A or doxorubicin alone. Similarly, a novel P-gp-specific MDR modulator, PGP-4008, in combination with doxorubicin showed inhibition of tumor growth. However, in contrast with the significant loss of body weight observed in the animals treated with the combination of cyclosporin A and doxorubicin, those treated with PGP-4008 plus doxorubicin did not experience weight loss. Therefore, this syngeneic solid tumor model provides a new in vivo system that can be used to evaluate the efficacy of P-gp inhibitors in an immune-competent host. This should allow improved prediction of the clinical utility of these compounds.

• Authors: Brian D Lee, Kevin J French, Yan Zhuang, Charles D Smith
• Journal: Oncology research (Oncol Res) Vol. 14 Issue 1 Pg. 49-60 ( 2003) ISSN: 0965-0407 [Print] United States
• PMID: 14552591 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• ATP Binding Cassette Transporter, Subfamily B, Member 1
• Acetanilides
• N-1-benzyl-2,3-dihydro-1H-pyrrolo(2,3-b)quinolin-4-yl-2-phenylacetamide
• Pyrroles
• Quinolines

Topics

• ATP Binding Cassette Transporter, Subfamily B, Member 1 (metabolism)
• Acetanilides
• Animals
• Blotting, Western
• Cell Line, Transformed
• Disease Models, Animal
• Drug Resistance, Multiple (physiology)
• Humans
• Mice
• Neoplasms, Experimental
• Pyrroles (metabolism)
• Quinolines (metabolism)