This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Spinelli, W. Articles by Ishii, D. N. Search for Related Content PubMed PubMed Citation Articles by Spinelli, W. Articles by Ishii, D. N.

Tumor Promoter Receptors Regulating Neurite Formation in Cultured Human Neuroblastoma Cells¹

Department of Pharmacology and the Cancer Research Center, College of Physicians and Surgeons of Columbia University, New York, New York 10032

The mouse skin tumor promoter phorbol-12, 13-dibutyrate (PDBU) reversibly enhanced neurite outgrowth in SH-SY5Y human neuroblastoma cells, whether serum was present or absent. The half-maximum response in serum occurred at 10 nM. The binding of [20-³H]phorbol-12, 13-dibutyrate ([³H]PDBU) was studied. Five mouse skin tumor promoters, which included teleocidin, mezerein, and three structural congeners of phorbol, enhanced neurite outgrowth and inhibited binding of [³H]PDBU, but two nonpromoting phorbol congeners did neither. Saccharin and cyclamate, promoters in rat bladder, did not inhibit [³H]PDBU binding. Binding of 10 nM [³H]PDBU at 37° was maximal within 5 min and stable for at least 5 hr. Down modulation of binding was not detected. Following binding at 37°, the dissociation rate in excess PDBU was biphasic, whether measured at 37° or at 4°. The Scatchard curve was also consistent with two types of sites, about 2.5 x 10⁵ sites/cell with K_d = 8.6 nM and 1.2 x 10⁶ sites with K_d = 125 nM. Negative cooperativity was not observed. In short-term assays, nerve growth factor (NGF) did not alter [³H]PDBU binding, and phorbol ester promoters did not alter ¹²⁵I-NGF binding. Furthermore, [³H]PDBU binding was unaltered following growth of cells for 1 week in PDBU or NGF, conditions under which neurite outgrowth was continuously enhanced, and other phenotypic expressions of differentiation are known to be increased. Specific [³H]PDBU binding sites were present in five neuroblastoma cell lines, two of which are responsive and three unresponsive by neurite outgrowth to promoters and NGF, suggesting the possibility of a common lesion in distal steps in the unresponsive lines.

¹ Supported in part by Grant R01 NS 14218 from the National Institute of Neurological Communicative Diseases and Stroke.

² Predoctoral fellow, recipient of support in part from the Dr. and Mrs. S. C. Wang Fund and from USPHS Training Grant GM 07182 from the Division of General Medical Sciences.

³ Recipient of USPHS Research Career Development Award 1K04 NS00375. To whom requests for reprints should be addressed.

Received 3/ 9/83. Accepted 6/ 6/83.