Matrix metalloproteinase-8 mediates the unfavorable systemic impact of local irradiation on pharmacokinetics of anti-cancer drug 5-Fluorouracil

Abstract

Concurrent chemoradiation with 5-fluorouracil (5-FU) is widely accepted for cancer treatment. However, the interactions between radiation and 5-FU remain unclear. Here, we evaluated the influence of local irradiation on the pharmacokinetics of 5-FU in rats. The single-fraction radiation was delivered to the whole pelvic fields of Sprague-Dawley rats after computerized tomography-based planning. 5-FU at 100 mg/kg was prescribed 24 hours after radiation. A high-performance liquid chromatography system was used to measure 5-FU in the blood. Matrix metalloproteinase-8 (MMP-8) inhibitor I was administered to examine whether or not RT modulation of 5-FU pharmacokinetic parameters could be blocked. Compared with sham-irradiated controls, whole pelvic irradiation reduced the area under the concentration versus time curve (AUC) of 5-FU in plasma and, in contrast, increased in bile with a radiation dose-dependent manner. Based on protein array analysis, the amount of plasma MMP-8 was increased by whole pelvic irradiation (2.8-fold by 0.5 Gy and 5.3-fold by 2 Gy) in comparison with controls. Pretreatment with MMP-8 inhibitor reversed the effect of irradiation on AUC of 5-FU in plasma. Our findings first indicate that local irradiation modulate the systemic pharmacokinetics of 5-FU through stimulating the release of MMP-8. The pharmacokinetics of 5-FU during concurrent chemoradiaiton therapy should be rechecked and the optimal 5-FU dose should be reevaluated, and adjusted if necessary, during CCRT.

Figure 1. The area under the concentration vs. time curve (AUC) of 5-fluorouracil (5-FU) 100 mg/kg administered to rats in the control, 0.5-Gy and 2-Gy groups.

The transverse axis illustrates time in minutes and the vertical axis represents the concentration of 5-FU. (A) Plasma. (B) Bile. Each group's data was collected from six rats.

Figure 2. Plasma alanine aminotransferase (ALT) levels in rats of the control, 5-FU-treated only, 2Gy-treated only, 0.5 Gy followed by 5-FU-treated and 2 Gy followed by 5-FU-treated groups.

The serum concentrations of alanine aminotransferase (ALT) levels were not significantly different between all tested groups. N = 5 for each group.

Figure 3. The cytokines respond to irradiation (RT) and 5-fluorouracil (5-FU) in plasma for control, RT 2 Gy alone, 5-FU alone, RT 0.5 Gy followed by 5-FU and RT 2 Gy followed by 5-FU groups.

(A) The level of transforming growth factor beta 1 (TGF-β1) in plasma. (B) The level of tumor necrosis factor alpha (TNF-α) in plasma. Each group's data was collected from five rats.

Figure 4. Cytokine profile of rat plasma treated with whole pelvic irradiation.

The amount of matrix metalloproteinase-8 (MMP-8) increased in 0.5-Gy and 2-Gy irradiated groups when compared with the control group. A map of the locations of cytokine antibodies spotted onto the protein chip is shown on the up side of the Figure. Dotted squares indicate the location of MMP-8. Each cytokine is represented by duplicate spots in the locations shown. Cytokine antibody arrays assay of (A) untreated control group, (B) whole pelvic irradiation (RT) with 2 Gy only, (C) 5-fluorouracil (5-FU) alone, (D) RT with 0.5 Gy followed by 5-FU and (E) RT with 2 Gy followed by 5-FU. The cytokine array image represents results of one of three independent experiments, which show similar patterns of expression.

Figure 5. Intracellular 5-fluorouracil (5-FU) levels for 50 µM 5-FU treated HepG2 (Human liver tumor-derived cells possessing biochemical profiles characteristic of normal hepatocytes) with or without 10 µg/mL recombinant MMP-8 by high performance liquid chromatography.

Figure 6. The plasma concentration versus time curve (AUC) of 5-FU post irradiation was reversed by the matrix metalloproteinase-8 (MMP-8) inhibitor.

The area under the plasma concentration versus time curve (AUC) of 5-FU 100 mg/kg administered to rats in the control group without solvent, control group with solvent, whole pelvic 2-Gy irradiation with solvent, and whole pelvic 2-Gy irradiation with solvent and MMP-8 inhibitor. The transverse axis illustrates time in minutes and the vertical axis represents the concentration of 5-FU in the plasma. Each group's data was collected from four rats.

Figure 7. Computed tomography was used for simulation of the whole pelvic field.

The cranial margin was set at the top of bilateral iliac crest for the whole pelvic field. Conventional radiotherapy was used to deliver the radiation dose via the anterior-posterior (AP) and PA portals.