The functioning of pituitary hormone outside the brain is found to show some association with Breast Cancer- Penn Medicine study

Posted by Haripriya Munipalli on Mon, Oct 8, 2012  
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The prolactin hormone is released by the pituitary gland present in the brain. The prolactin that is secreted in the brain will get transported to the body cells by the blood stream. The hormone is known to show its impact on the metabolic and reproductive activities going on in the body cells. The Prolactin is found to be regulating the lactation in the breast. There are also research studies done recently which say that Prolactin is released by the tissues in the body other than in the brain. In spite of the research evidences of its production outside the pituitary gland, the regulation of this hormone in those tissues is not yet clear.


There was a research study performed by Dr. Lewis A. Chodosh, Chairman of the department of Cancer Biology at Perelman School of Medicine, University of Pennsylvania. According to the results of this study, Dr. Lewis has conveyed in “Genes & Development”, that a signaling pathway of PI3K-Akt that is present in the mice mammary glands, is oncogenic. When this pathway is triggered, it induces the Breast cells to secrete Prolactin. This process further is known to stimulate the Stat5, epithelial differentiation in mammary gland cells and synthesis of milk in virgin mice within few hours period.


Dr. Chodosh said that all the changes described above were seen occurring even in the absence of the hormonal and developmental conditions that normally prevail during pregnancy. The Penn Medicine team has found that mice in which the Akt genes are mutated could not stimulate Stat5. Inactivation of Stat5 did not initiate lactation in the mice that gave birth to little ones and the mice could not produce prolactin in the mammary glands. But, prolactin was normally seen present in usual levels in the circulating blood.


The above investigation revealed that the production of prolactin in the mammary glands is managed by PI3K-Akt signaling pathway. The result of the study also identifies a physiological function of prolactin that is originated from the tissues other than the pituitary gland at the time of important developmental stages that are critical for the offspring endurance.


It was thought that Prolactin was playing role in causing human breast cancer. However, Breast Cancer was thought to be caused due to the circulating Prolactin that is released by the pituitary gland. As the PI3K-Akt pathway is triggered usually in human cancers, the results of this study tell us that there is a great possibility for breast produced prolactin to show major impact on Breast Cancer. In some of the Breast Cancers, the mammary gland cells were detected to produce prolactin. The researchers have projected that mammary gland produced prolactin was directly responsible for Breast Cancer development than the prolactin released by Pituitary gland. The extra-pituitary hormone is known to provide pro-survival signals to the breast cancer cells. By targeting the effects of prolactin and inhibiting them, the anti-cancer drugs can be developed.


Dr. Chodosh explains that PI3K-Akt pathway is the oncogenic pathway that is mostly stimulated in human cancers and is also identified as the regulator of prolactin synthesis in the mammary gland. These two findings were observed to have impending inferences to recognize the human breast cancer pathology and improve its treatment methods.


Main Source: Penn Medicine News Release; 1st October, 2012.


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