Altered mitochondrial cytochrome b gene expression during the regression of hemangioma

Hemangioma is a primary tumor of microvasculature. Its development typicall y exhibits a proliferative phase followed by an involuting phase that conti nues into the involuted phase. Although apoptosis has been reported, the me chanisms regulating the spontaneous regression of hemangioma are largely un known. The authors recently demonstrated up-regulation of the mitochondrial cytochrome b gene in hemangioma associated with steroid-induced regression . The present study investigated whether a similar change occurred during s pontaneous regression. Biopsy material was obtained from I I patients with hemangiomas at different phases of development. In one of these patients, a biopsy was taken from the proliferative, involuting, and involuted areas o f the hemangioma. In another patient, a biopsy was taken before and 5 weeks after the intralesional administration of steroids. From each tissue speci men, RNA was isolated and subjected to reverse transcriptase-polymerase cha in reaction analysis by use of specific primers for the human mitochondrial cytochrome b gene. Semiquantitative reverse transcriptase-polymerase chain reaction analysis revealed that the strongest expression of the mitochondr ial cytochrome b transcripts was in specimens taken from hemangiomas in the involuting phase compared with those from the proliferative and involuted phases. The authors concluded that mitochondrial cytochrome b is associated with both the spontaneous and the steroid-induced regression of hemangioma , probably by regulating apoptosis.