[18F]2-fluoro-2-deoxy-D-glucose incorporation by AGS gastric adenocarcinoma cells in vitro during response to epirubicin, cisplatin and 5-fluorouracil

Abstract

Decreased tumour [(18)F]2-fluoro-2-deoxy-D-glucose ((18)FDG) incorporation is related to response however its significance at the cell level in gastro-oesophageal cancer and how it relates to cell death is unknown. Here human gastric adenocarcinoma (AGS) cells were treated with lethal dose 10 and 50 (LD(10) and LD(50)), determined by using the MTT assay, of the three drugs, epirubicin, 5-fluorouracil and cisplatin, commonly used in the treatment of patients with gastro-oesophageal cancer. (18)FDG incorporation was determined after 48 and 72 h of treatment with each drug and related to drug-induced changes in glucose transport, hexokinase activity, cell cycle distribution and annexin V-PE binding (a measure of apoptosis). Treatment of cells for 48 and 72 h with LD(50) doses of cisplatin resulted in reductions in (18)FDG incorporation of 27 and 25% respectively and of 5-fluorouracil reduced (18)FDG incorporation by 34 and 33% respectively: epirubicin treatment reduced incorporation by 30 and 69% respectively. Cells that had been treated for 72 h with each drug were incubated in drug-free media for a further 6 days to determine their ability to recover. Comparison of the ability to recover from the chemotherapy agent, with (18)FDG incorporation before the recovery period allowed an assessment of the predictive ability of (18)FDG incorporation. Cells treated with either 5-fluorouracil or cisplatin demonstrated recovery on removal of the drug. In contrast, cells treated with epirubicin did not recover corresponding with the greatest 72 h treatment decrease in (18)FDG incorporation. In contrast to adherent cells treated with cisplatin or 5-fluorouracil, adherent epirubicin-treated cells also exhibited very high levels of apoptosis. Glucose transport was decreased after each treatment whilst hexokinase activity was only decreased after 72 h of treatment with each drug. There was no consistent relationship observed between (18)FDG incorporation and cell cycle distribution. Our results show that at the tumour cell level in gastric tumour cells, decreased (18)FDG incorporation and glucose transport, accompanies therapeutic growth inhibition. (18)FDG incorporation is particularly diminished in cells exhibiting apoptosis.

Figure 1

Cellular [¹⁸F]2-fluoro-2-deoxy-D-glucose (¹⁸FDG) incorporation, per treated flask, after 48 (A) and 72 (B) h treatment with lethal dose 10 (LD₁₀) (white) and LD₅₀ (grey) doses of epirubicin, 5-FU or cisplatin expressed as a percentage of incorporation by untreated controls (E=epirubicin, C=cisplatin, F=5-fluorouracil).

Figure 2

Cellular [¹⁸F]2-fluoro-2-deoxy-D-glucose (¹⁸FDG) incorporation, per milligram cellular protein, after 48 (A) and 72 (B) h treatment with lethal dose 10 (LD₁₀) (white) and LD₅₀ (grey) doses of epirubicin, 5-FU or cisplatin expressed as a percentage of incorporation by untreated controls (E=epirubicin, C=cisplatin, F=5-fluorouracil).

Figure 3

Cellular [³H]O-methylglucose (³H-OMG) uptake, per milligram of cellular protein, after 48 (A) and 72 (B) h incubation with lethal dose 10 (LD₁₀) (white) and LD₅₀ (grey) expressed as a percentage of the control (E=epirubicin, C=cisplatin, F=5-fluorouracil).

Figure 4

Cellular hexokinase (HK) activity, expressed as milliunits per milligram of cellular protein as a percentage of control (E=epirubicin, C=cisplatin, F=5-fluorouracil), after 48 (A) and 72 (B) h exposure to lethal dose 10 (LD₁₀) (white) and LD₅₀ (grey) doses of epirubicin, cisplatin and 5-FU (E=epirubicin, C=cisplatin, F=5-fluorouracil).

Figure 5

Determination of the growth inhibitory effect of each agent by performing MTT measurements 6 days after treatment with cisplatin (A), epirubicin (B) and 5-FU (C) for 72 h. Cell survival is expressed as absorbance as measured on spectrophotometer.