Figure 7.

Gefitinib reduced plasma total calcium and PTHrP concentrations in nude mice with HARA xenografts and hypercalcaemia. (A) Hypercalcaemic mice with HARA xenografts (n=5) were treated daily for 3 days with gefitinib (200 mg kg⁻¹, p.o.). The first treatment occurred at the onset of hypercalcaemia. Treatment resulted in a statistically significant decrease in total plasma calcium concentrations compared to pretreatment values at 78 h and compared to untreated mice (n=5). Repeated measures one-way ANOVA, mean±s.e.m., ^*P=0.042 relative to treated; ^§P=0.001 relative to baseline. (B) Plasma PTHrP concentrations were measured using plasma samples collected before HARA cell injections (baseline) and at 78 h after gefitinib or placebo treatment. Experiments included five gefitinib-treated mice and five untreated mice. Baseline PTHrP values were from the same 10 mice. In the gefitinib-treated mice (black column), there was a marked reduction (60%) in plasma PTHrP concentrations when compared to untreated mice (white columns). Untreated and gefitinib-treated mice with HARA xenografts had PTHrP concentrations that were significantly greater than baseline at 78 h. ^*P=0.047 relative to treated; ^§P=0.001 relative to baseline. (C) Gefitinib treatment reduced PTHrP mRNA levels in RWGT2 tumours. RNA was extracted from tumours that were removed 78 h after hypercalcaemia was identified. cDNA was produced with the MultiScribe Reverse Transcriptase Kit (Applied Biosystems, Foster City, CA, USA) and QRT-PCR performed. PTHrP to GAPDH mRNA was assayed by QRT-PCR. The ratio of PTHrP to GAPDH mRNA in the gefitinib-treated tumours (n=3) was decreased 90% as compared to untreated (n=4). The QRT-PCR was repeated twice with similar results. ^*P=0.02.