Elevated levels of head activator in human brain tumors and in serum of patients with brain and other neurally derived tumors.

In normal human tissue high concentrations of the neuropeptide head activator are found in the hypothalamus, in the retina, and in the gastro-intestinal tract. Up to 100-fold elevated levels of head activator over neighbouring tissue were found in tumors of the brain, especially in tumors of neural origin like astrocytoma and glioblastoma, but also in meningioma. Coincident with elevated tissue levels, an increased secretion into the general circulation was observed. Elevated levels of head activator in the blood were also observed in patients with tumors in peripheral locations, especially in tumors of gastrointestinal tract and/or of neuroendocrine origin. After tumor removal, the head activator levels in the blood dropped to normal values suggesting a possible role of head activator in neuroendocrine tumorigenesis.