Growth hormone supplementation increased latency to tumourigenesis in Atm-deficient mice.

Growth hormone (GH) is important for cell growth and differentiation, has multiple effects on lymphoid tissue and may promote blast cell proliferation and cancer development. We studied the effect of GH on longevity and tumour formation in Atm-deficient mice, an established model of the human cancer prone syndrome ataxia telangiectasia (AT). AT is a devastating recessive disorder that is characterized by progressive cerebellar ataxia, immunodeficiency, chromosomal instability and cancer susceptibility. Since AT patients also show endocrinological abnormalities the question has been raised as to whether GH therapy could be beneficial and/or increase the cancer risk in AT. We found that treatment with GH significantly increased longevity of Atm-deficient mice. In addition, GH ameliorated locomotoric behaviour and improved T-cell immunity. Thus, our data demonstrated that GH treatment is not necessarily accompanied by increased cancer development in diseases with chromosomal instability and cancer susceptibility and might be beneficial for AT patients.