title: [Neoplastic effect of indomethacin in N-methyl-N-nitrosourea induced mammary carcinogenesis in female rats].
abstract: BACKGROUND
  High levels of prostaglandins found in many neoplastic tissues, especially in colon cancer and breast cancer, suggest a role of cyclooxygenase in the process of carcinogenesis.
  
  
  METHODS
  The aim of this study was to analyse the chemopreventive potential of non-steroidal inflammatory drug indomethacin and its combination with pineal hormone melatonin in rat mammary carcinogenesis induced by N-methyl-N-nitrosourea. Indomethacin was administered 3 times a week and melatonin 4 times a week, both substances in a concentration of 20 µg/ml of drinking water. Chemoprevention began approximately 2 weeks before carcinogen administration and lasted until the end of the experiment 25 weeks later.
  
  
  RESULTS
  Indomethacin administered alone and in combination with melatonin stimulated the growth of mammary tumors. We found a significant increase in the average tumor volume caused by indomethacin alone by 126%, and in combination with melatonin by 104% compared to the control group. Indomethacin administered alone increased the incidence of tumors by 21.5% (also in combination with melatonin) and reduced the tumor latency by 17 days compared to controls. Melatonin alone significantly reduced tumor volume in comparison with control animals. During the long-term administration, both substances were well tolerated by animals.
  
  
  CONCLUSIONS
  Indomethacin, a predominant cyclooxygenase inhibitor-1, showed significant neoplastic effects in the prevention of N-methyl-N-nitrosourea induced rat mammary carcinogenesis. This finding is in strong contrast to our previous experiment, where indomethacin in 7,12-dimethylbenz(a)anthracene-induced rat mammary carcinogenesis revealed marked antineoplastic effects.
authors.affiliation: Ustav lekarskej biologie, Universita Komenskeho, Slovenska Republika.
authors.forename: P
authors.initials: P
authors.lastname: Kubatka
authors.forename: K
authors.initials: K
authors.lastname: Kalická
authors.forename: B
authors.initials: B
authors.lastname: Bojková
authors.forename: I
authors.initials: I
authors.lastname: Ahlers
authors.forename: E
authors.initials: E
authors.lastname: Ahlersová
authors.forename: M
authors.initials: M
authors.lastname: Péč
mesh_terms: D000818:Animals; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D018890:Chemoprevention; D005260:Female; D007213:Indomethacin / Q000627:therapeutic use*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000517:prevention & control*; D008550:Melatonin / Q000627:therapeutic use*; D008770:Methylnitrosourea; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016588:Anticarcinogenic Agents; D008770:Methylnitrosourea; D008550:Melatonin; D007213:Indomethacin