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Levels of viral glycoprotein provide a dose-dependent measure of tumor cell inhibition
1Department of Microbiology, Texas Tech University Health Sciences Center, Lubbock 79430.
Abstract:
A chemosensitivity assay utilizing small replicate Mm5mt/c1 C3H mammary tumor cell cultures was developed to determine whether changes in viral antigen expression and release into culture fluids could be utilized as an in vitro measure of chemotherapeutic drug effect. The 52,000 MW viral envelope glycoprotein (gp52) of the mouse mammary tumor virus (MMTV) was measured in culture fluids of control and drug-treated cultures while cell density was simultaneously determined by cell staining and OD 664 mu determination. While extracellular gp52 levels and cell density both progressively increased over 72 hours for control cultures, treatments with doxorubicin resulted in dose-dependent declines in both parameters at 24, 48, and 72 hours. Comparison of doxorubicin dosages for 50% reduction (ED50s) in both parameters (0.68uM and 1.1uM) revealed a similar coordinate reduction in both cell density and MMTVgp52. When gp52 levels were further examined as a general measure of effect for a broad spectrum of 6 drugs with differing mechanisms of action, coordinate declines in cell density and MMTVgp52 provided a time and dose-dependent dual measure of effect for each of the drugs tested. Coordinate declines resulted in the same following hierarchy of concentration-dependent drug potency: methotrexate greater than 5-fluorouracil greater than doxorubicin greater than N [phosphonacetyl- L aspartic acid] (PALA) greater than cis-platinum greater than cyclophosphamide. The dual measures of therapeutic effect afforded by this assay argue for its use as an in vitro measure of effect for optimizing drug treatments.
Insights
A novel chemosensitivity assay measures mouse mammary tumor virus (MMTV) glycoprotein 52 (gp52) and cell density to assess chemotherapy drug effectiveness. This dual measurement provides a reliable in vitro method for optimizing cancer drug treatments.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Assessing chemotherapeutic drug efficacy in vitro is crucial for optimizing cancer treatment.
- Viral antigen expression can potentially serve as a biomarker for drug response.
Purpose of the Study:
- To develop and validate a chemosensitivity assay using viral antigen expression as an in vitro measure of chemotherapeutic drug effect.
- To evaluate the correlation between viral antigen levels and cell density as indicators of drug response.
Main Methods:
- Developed a chemosensitivity assay using Mm5mt/c1 C3H mammary tumor cell cultures.
- Measured extracellular mouse mammary tumor virus (MMTV) envelope glycoprotein (gp52) and cell density over 72 hours.
- Treated cultures with doxorubicin and a panel of six other chemotherapeutic agents.
Main Results:
- Doxorubicin treatment resulted in dose-dependent declines in both extracellular gp52 and cell density.
- ED50 values for doxorubicin were comparable for both gp52 reduction and cell density reduction.
- The assay demonstrated a consistent hierarchy of drug potency across six different chemotherapeutic agents.
Conclusions:
- The developed assay, measuring both MMTV gp52 and cell density, provides a reliable dual in vitro measure of chemotherapeutic drug effect.
- This assay can be utilized for optimizing drug treatments and evaluating drug potency.
- Viral antigen expression serves as a viable indicator for assessing drug efficacy in vitro.
