Journal of Neuroscience, Vol 9, 1199-1212, Copyright © 1989 by Society for Neuroscience
Human medullary thyroid carcinoma: characterization of the serotonergic and neuronal properties of a neurectodermally derived cell line
H Tamir, KP Liu, RF Payette, SC Hsiung, M Adlersberg, EA Nunez and MD Gershon
Division of Neuroscience, New York State Psychiatric Institute, New York 10032.
Parafollicular (PF) cells have been found to be a good model system for the
study of serotonergic cellular mechanisms relevant to neurons. PF cells are
derived from the same region of the neural crest that gives rise to the
neurons of the gut and are capable of extending neurofilament-bearing
neuritic processes. PF cells also synthesize 5- hydroxytryptamine (5-HT)
and costore 5-HT in the same vesicles as the specific 5-HT-binding protein,
45 kDa SBP. A hypothesis has been advanced that PF cells and enteric
neurons share a common developmental precursor. The present investigation
was undertaken in order to determine whether a human medullary thyroid
carcinoma (MTC) cell line, which is derived from PF cells, sufficiently
mimics PF cells that it can be substituted for them in investigations of
serotonergic cellular biology. In contrast to PF cells, MTC cells can be
propagated in vitro to provide adequate amounts of material for biochemical
studies. MTC cells were found to contain neuropeptides, including
calcitonin, calcitonin gene-related peptide, and somatostatin, which have
also been reported to be present in PF cells and enteric neurons. MTC cells
also were observed to store endogenous 5-HT, to be able to synthesize 3H-5-
HT from 3H-L-tryptophan, and to take up 3H-5-HT from the ambient medium by
a carrier-mediated mechanism very similar to that of serotonergic neurons.
In addition, the longterm accumulation of 3H-5-HT in MTC cells was
antagonized by reserpine, suggesting that the cells contain 5-HT storage
vesicles that, like the synaptic vesicles of serotonergic neurons, are
characterized by a reserpine-sensitive transporter of biogenic amines. MTC
cells also contain type A, but not type B, monoamine oxidase. Finally, MTC
cells were found to contain both 45 and 56 kDa SBP. MTC cells thus retain a
great many of the properties of PF cells, and, like PF cells, they are
serotonergic cells with characteristics similar to serotonergic neurons.
Substantial differences were found in the content of immunoreactive 5-HT
and neuropeptides in individual MTC cells. Moreover, the release of newly
synthesized 5-HT to the medium exceeded the ability of the cells to store
the amine. Studies of the ultrastructure of the MTC cells revealed a
limited and highly variable number of secretory granules, probably
accounting for their limited 5-HT storage capacity and for the
heterogeneity of immunostaining with antisera to 5-HT or
neuropeptides.(ABSTRACT TRUNCATED AT 400 WORDS)