ABSTRACT
Dopamine (DA) is associated with a variety of tumors in different systems throughout the body. In the hematologic system, there is evidence for a role of DA in leukemia, lymphoma, and multiple myeloma. Both DA and the dopamine and cyclic AMP-regulated phosphoprotein (DARPP or Dp32) and its truncated isoform tDP are expressed in GI-related tumors, including gastric, colorectal, and hepatic. In pancreatic cancer, chimeric molecules, directed against both somatostatin and DA receptors (DAR), showed a therapeutic promise. Evidence derived from studies with cultured cells showed involvement of DA and its receptors in lung, kidney and bladder cancers. Melanoma, the most aggressive skin cancer, shares a biosynthetic pathway in the production of melanin and DA. Older studies in the 1970s, using cultured cells, tumor-bearing mice, and small clinical trials, reported suppression of melanoma by L-Dopa. Activation of the cGMP/protein kinase G (PKG) axis was very effective in the inhibition of head and neck cancer, although a direct connection to the dopaminergic system is still missing. Among more than 120 types of brain and nervous system tumors, DA is involved in glioblastoma, neuroblastoma, meningiomas, and neuroendocrine tumors.
