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Published on: September 22, 2019
Cellular ATP depletion by LY309887 as a predictor of growth inhibition in human tumor cell lines
1Cancer Research Unit, University of Newcastle upon Tyne, United Kingdom.
Abstract:
The antifolate LY309887 is a specific glycinamide ribonucleotide formyltransferase inhibitor that blocks de novo purine synthesis and produces a depletion of purine nucleotides. The activity of LY309887 in six human tumor cell lines has been examined by growth inhibition and clonogenic assay after continuous exposure for three cell doubling times and by ATP depletion at 24 h. Three cell lines (CCRF-CEM, MCF7, and GC3) were sensitive to LY309887-induced growth inhibition (IC50: 5.6-8.1 nM), whereas the other cell lines (COR-L23, T-47D, and A549) were comparatively resistant (IC50: 36-55 nM). Sensitivity to LY309887 cytotoxicity was consistent with sensitivity to growth inhibition in four of five cell lines tested (MCF7/GC3: 0.01% survival and COR-L23/T-47D: 1-5% survival at 100 nM LY309887). LY309887-induced ATP depletion was measured by luciferase-based ATP assay and confirmed by high performance liquid chromatography measurements. There was a linear relationship between ATP depletion and growth inhibition when data were analyzed for all six cell lines (r2 = 0.93; P < 0.0001). Depletion of 24-h cellular ATP concentrations to < 1 mM was associated with both cell growth inhibition and cytotoxicity in all cell lines studied. In conclusion, cellular ATP depletion induced by LY309887 can be used to predict growth inhibition and cytotoxicity in human tumor cells.
Insights
The antifolate LY309887 inhibits purine synthesis, causing ATP depletion. This depletion predicts tumor cell growth inhibition and cytotoxicity across various human cancer cell lines.
Area of Science:
- Biochemistry
- Molecular Biology
- Cancer Research
Background:
- Antifolates are crucial in cancer chemotherapy.
- LY309887 specifically inhibits glycinamide ribonucleotide formyltransferase.
- This inhibition disrupts de novo purine synthesis, leading to purine nucleotide depletion.
Purpose of the Study:
- To evaluate the activity of LY309887 in human tumor cell lines.
- To assess the correlation between LY309887-induced ATP depletion and its cytotoxic effects.
Main Methods:
- Cell growth inhibition and clonogenic assays were performed.
- ATP depletion was measured using luciferase-based assays and HPLC.
- Continuous exposure for three cell doubling times was employed.
Main Results:
- Six human tumor cell lines exhibited varying sensitivity to LY309887 (IC50 range: 5.6–55 nM).
- Cytotoxicity correlated with growth inhibition.
- A linear relationship (r2 = 0.93) was observed between ATP depletion and growth inhibition.
Conclusions:
- LY309887 effectively inhibits human tumor cell growth and induces cytotoxicity.
- Cellular ATP depletion is a reliable predictor of LY309887's anti-cancer effects.
- LY309887 demonstrates potential as a chemotherapeutic agent targeting purine synthesis.
