Table 2

Tumor aromatase activity levels, tumor E2 concentrations, and serum E2 levels in MCF-7Ca, UMB-1Ca, long-term letrozole-treated (LTLT), and transplanted letrozole-treated (TLT) tumors grown in female ovariectomized athymic nude mice

TumorAromatase activity (fmol/mg protein/h)Tumor estradiol (pg/g tissue)Serum estradiol (pg/ml)
MCF-7Ca (Δ4A)213.55 ± 11.29a2305 ± 425.00b62c
UMB-1Ca (Δ4A)252.24 ± 10.132080 ± 60.0062
LTLT200.81 ± 16.19240 ± 20.0032
TLT (Δ4A)289.90 ± 23.511890 ± 120.0063
TLT (Letrozole)322.39 ± 25.02440 ± 30.0019
TLT (Anastrozole)293.11 ± 20.50651 ± 201.0011
TLT (Formestane)423.09 ± 35.861084 ± 328.008
TLT (Vehicle)335.75 ± 24.73420 ± 80.007
  • a Values represent the means and SE from three tumors from each group.

  • b Values represent the means and SE from two tumors from each group.

  • c Values represent the means and SE from serum pooled from three to five animals.