Number of pregnancies and ovariectomy modify mammary carcinoma development in transgenic HER-2/neu female mice

• Published in: Cancer letters Vol. 193; no. 1; pp. 49 - 55
• Main Authors: Anisimov, Vladimir N., Popovich, Irina G., Alimova, Irina N., Zabezhinski, Mark A., Semenchenko, Anna V., Yashin, Anatoli I.
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier Ireland Ltd 10-04-2003; Elsevier Limited
• Subjects: Age Factors; Aging; Animals; Breast cancer; Carcinoma - genetics; Carcinoma - pathology; Female; Genes, erbB-2 - genetics; HER-2/neu transgenic mice; Homozygote; Mammary carcinoma; Mammary Neoplasms, Animal - genetics; Mammary Neoplasms, Animal - pathology; Mammary Neoplasms, Experimental - genetics; Mammary Neoplasms, Experimental - pathology; Mice; Mice, Transgenic; Models, Theoretical; Ovariectomy; Ovary - physiology; Ovary - surgery; Pregnancy; Pregnancy, Animal; Receptor, ErbB-2 - physiology; Risk Factors; Rodents; Time Factors; Womens health; Pregnancy; Mammary carcinoma; HER-2/neu transgenic mice; Ovariectomy
• ISSN: 0304-3835; 1872-7980
• DOI: 10.1016/S0304-3835(02)00721-8

We studied effect of pregnancy and ovariectomy on the development of mammary tumors in homozygous female
HER-2/neutransgenic mice. The mean life span of uniparous mice was decreased by 16% in comparison to the control (
P<0.05) and of mice which have two pregnancies decreased by 11% (
P<0.05). Ovariectomy at the age of 2 months was followed by 32.7% increase in mean life span of mice. The incidence or multiplicity of mammary adenocarcinomas did not change in uniparous mice, whereas the size of the tumors and metastatic potential were decreased as compared to the virgins. When mice have two full-time pregnancies, there was an increase in multiplicity of mammary carcinomas and significant (2.1-fold) decrease in the survival time of tumor-bearing mice. Ovariectomy significantly decreased the total incidence of mammary carcinomas, the number of tumors per tumor-bearing animal, and inhibited metastasizing into lungs. Our results indicate that pregnancy accelerated the development of mammary adenocarcinomas in transgenic
HER-2/neu mice whereas ovariectomy inhibits their development.