AMP IS A COMPONENT OF THE LOW-MOLECULAR-WEIGHT MITOGENIC ACTIVITY PRESENT IN HUMAN PITUITARY-TUMORS

The mitogenic activity of extracts of human non-functional pituitary t umours has been studied. Previously we have reported that the tumour e xtracts could be resolved into both high (>13,000) and low (<3,000) mo lecular weight fractions using Sephadex G-50 chromatography. Mitogenic activity was assayed by looking at trichloroacetic acid precipitable H-3-thymidine incorporation into GH(3) cells. We have now purified the major component of the low molecular weight mitogenic fraction using reversed phase HPLC; the material was identified and found to be 5'-ad enosine monophosphate (5'-AMP) using electron spray mass spectrometry. The mitogenic activity of 5'-AMP and the purified tumour extract was confirmed as both produced an increase in GH(3) cell number after 4 da ys of treatment. In conclusion our results show that the major compone nt of the low molecular weight mitogenic activity in human non-functio nal pituitary tumour extracts is 5'-AMP