Professor Masayuki Komada of the Cell Control Engineering Research Unit, Institute of Science and Technology Innovation, Tokyo Institute of Technology and others discovered a new gene that suppresses the onset of breast cancer in experiments using mice.
In recent years, it is estimated that 12 in 1 Japanese women will suffer from breast cancer in their lifetime, and it is increasing worldwide along with colorectal cancer and lung cancer, which has become a major social problem.
During pregnancy, mammary epithelial cells proliferate due to the action of female hormones such as estrogen to prepare for breastfeeding after childbirth, and the mammary gland develops to prepare for breastfeeding.It has been thought that mammary epithelial cells stop growing in the late pregnancy when the mammary gland is fully developed, but if this growth stop mechanism is disrupted, the cells do not stop growing, leading to the development of breast cancer.However, the molecular mechanism by which the proliferation of mammary epithelial cells is suppressed in the latter half of pregnancy has not been clarified.
Professor Komada et al. Created and analyzed mice (Nrk-deficient mice) that could not produce protein kinase (Nrk protein) encoded on the X chromosome.During the breeding process, it was discovered that the mammary glands of female Nrk-deficient mice that experienced pregnancy and childbirth often formed tumors (humps).Furthermore, when Nrk-deficient female mice were mated with male mice and bred for 15 months, breast tumors = breast cancer were formed in Nrk-deficient mice at a very high frequency (10 out of 9).This tumor was not observed in Nrk-deficient mice that had never been pregnant or gave birth.
The study reveals that the Nrk protein is expressed in the mammary gland in late pregnancy and plays a role in preventing the development of breast cancer by stopping the growth of mammary epithelial cells.
The homologous gene of the mouse Nrk gene was also present in humans, and the mammary tumor in Nrk-deficient mice was close to luminal-B type in the subtype classification of human breast cancer.From this, it is expected that the results of this research will lead to the suppression mechanism of human breast cancer, leading to the elucidation, diagnosis and treatment of the onset mechanism.
The research results were published in the electronic version of "The American Journal of Pathology", the journal of the American Society of Research and Pathology, published on September 2016, 9.
