Rare Cancers Yield Potential Source of Tumor Growth
According to an article published in the New England Journal of Medicine (2012; 367:922-930), a genetic mutation has been discovered that appears to increase production of red blood cells in tumors. The discovery, based on analysis of tissue from rare endocrine tumors, may help clarify how some tumors generate a new blood supply to sustain their growth. According to the authors, the finding could lead to information on how to hinder the growth of tumors and treat cancers associated with excessive production of red blood cells.
The study analyzed tumors from two patients with a rare type of tumor, known as a paraganglioma,. which forms from chromaffin cells outside the adrenal glands, near blood vessels and nerves. Chromafin cells produce the hormone norepinephrine (adrenaline.) One patient also had a rare tumor of the duodenum known as a somatostatinoma. Since birth, both patients had polycythemia, a rare disease in which the body produces too many red blood cells.
Results showed that the tumor tissue contained an alteration in one of the family of genes called hypoxia-inducible factors (HIFs). HIFs have been implicated in the development of tumors and the progression of cancers. HIFs are made of two subunits, termed alpha and beta, and those subunits have been found to play a role in cancers. In the current study, it was found that the altered HIF2A gene generated proteins that were broken down more slowly than the typical form of the gene. In the presence of these proteins, there was also a documented increased levels of a hormone that stimulates the production of red blood cells.
HIF genes are most active in conditions of low oxygen, such as in tumor tissue. In previous studies it was observed that a patient’s polycythemia disappeared after a paraganglioma or pheochromocytoma (chromaffin cell tumors arising in the adrenal gland) was removed.