Serotonin metabolism is dysregulated in cholangiocarcinoma, which has implications for tumor growth.
Cholangiocarcinoma is a devastating cancer of biliary origin with limited treatment options. Symptoms are usually evident after blockage of the bile duct by the tumor, and at this late stage, they are relatively resistant to chemotherapy and radiation therapy. Therefore, it is imperative that alternative treatment options are explored. We present novel data indicating that the metabolism of serotonin is dysregulated in cholangiocarcinoma cell lines, compared with normal cholangiocytes, and tissue and bile from cholangiocarcinoma patients. Specifically, there was an increased expression of tryptophan hydroxylase 1 and a suppression of monoamine oxidase A expression (enzymes responsible for the synthesis and degradation of serotonin, respectively) in cholangiocarcinoma. This resulted in an increased secretion of serotonin from cholangiocarcinoma and increased serotonin in the bile from cholangiocarcinoma patients. Increased local serotonin release may have implications on cholangiocarcinoma cell growth. Serotonin administration increased cholangiocarcinoma cell growth in vitro, whereas inhibition of serotonin synthesis decreases tumor cell growth both in vitro and in vivo. The data presented here represent the first evidence that serotonin metabolism is dysregulated in cholangiocarcinoma and that modulation of serotonin synthesis may represent an alternative target for the development of therapeutic strategies.
Alpini
Gianfranco
G
Department of Medicine, Texas A&M Health Science Center, College of Medicine, Scott & White Hospital, Temple, TX 76504, USA.
Invernizzi
Pietro
P
Gaudio
Eugenio
E
Venter
Julie
J
Kopriva
Shelley
S
Bernuzzi
Francesca
F
Onori
Paolo
P
Franchitto
Antonio
A
Coufal
Monique
M
Frampton
Gabriel
G
Alvaro
Domenico
D
Lee
Sum P
SP
Marzioni
Marco
M
Benedetti
Antonio
A
DeMorrow
Sharon
S
D000818:Animals; D001650:Bile Duct Neoplasms / Q000378:metabolism* / Q000473:pathology; D001653:Bile Ducts, Intrahepatic; D045744:Cell Line, Tumor; D018281:Cholangiocarcinoma / Q000378:metabolism* / Q000473:pathology; D053379:Chromogranin A / Q000032:analysis; D010134:Fenclonine / Q000494:pharmacology; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008995:Monoamine Oxidase / Q000235:genetics; D012701:Serotonin / Q000378:metabolism*
D053379:Chromogranin A; D012701:Serotonin; D008995:Monoamine Oxidase; D010134:Fenclonine