Table 1.

Response of SR+ MCF-7 human breast cancer xenografts to perfusion in situ with a physiologic nocturnal concentration of melatonin

Treatment[3H]Thymidine incorporation (dpms/μg DNA)Linoleic acid uptake (% supply)13-HODE production (ng/min/g)cAMP (nmol/g)
Controls47.4 ± 3.916.7 ± 1.70.97 ± 0.170.55 ± 0.11
Melatonin13.6 ± 1.6 *000.33 ± 0.12 *
Melatonin + 13-HODE74.8 ± 6.30333.17 ± 19.020.68 ± 0.06
13-HODE78.0 ± 6.517.2 ± 3.2363.18 ± 10.620.78 ± 0.17
  • NOTE: Effects of perfusion of tissue-isolated SR+ MCF-7 human breast cancer xenografts in situ with synthetic melatonin (1 nmol/L) in the presence or absence of 13-HODE (12 μg/mL) on [3H]thymidine incorporation into DNA, linoleic acid uptake, 13-HODE formation, and cAMP levels. Individual tumors (n = 3-4) were perfused over a 2-hour period (06:30 to 08:30 h) with whole blood collected from tumor-free donor rats during the early light phase when endogenous melatonin levels were low. Synthetic melatonin and 13-HODE were added to the whole-blood perfusate to achieve final concentrations of 1 nmol/L (232 pg/mL) and 12 μg/mL, respectively. Values are means ± SE.

  • * P < 0.05 vs controls and melatonin + 13-HODE (comparisons of relevance).