Growth Hormone Regulation of Gene Expression Analysis of Bcl6, Cyclin D2 and Blimp 1 genes
Growth Hormone (GH) is a regulator of proto-oncogenes that are differentially expressed in cancerous and diabetic cells. GH regulates Bcl6, a transcriptional repressor highly expressed in B cell lymphoma cells. Bcl6 expression has been associated with Cyclin D2 and Blimp 1, genes important in differentiation and proliferation of cells and when abnormally expressed can lead to cancer. Cultures of pre-adipocytes and B-cells were treated with GH over a time course from 0 to 24 hours and varying dosage of 0, 5, 50 and 500 of Human or Ovine GH in order to test the time, dose response and specificity of the effect of GH. RNA extracts of treated cells were analyzed using qPCR. Bcl6 was inhibited after 0.5 hours in presence of 50 ng/mL of human GH. The Bcl6 antagonist Blimp 1 was up regulated by GH at 4 hours and 50 ng/mL of human GH. Cyclin D2 was inhibited at 4 hours in presence of 5 ng/mL hGH and oGH. The mechanism through which GH mediates the relationship between Bcl6, Blimp 1 and Cyclin D2 may involve miRNA 127. GH treatment increased the levels of miRNA 127 and this activation corresponded to inhibition of the miRNA 127 target, Bcl6.