Regulation of Bcl-2 oncoprotein levels with differentiation of human neuroblastoma cells.
When established in culture, human neuroblastoma cell lines typically are comprised of heterogeneous cellular subpopulations, including neuroblastic (N-type), substrate-adherent (S-type), and intermediate (I-type) cells that can be distinguished by their characteristic morphologies and expression of differentiation-associated antigens. Here we examined the relative levels of the Bcl-2 oncoprotein in 15 clones derived from four different neuroblastoma cell lines. Among six clones isolated from the SK-N-SH line, levels of p26-Bcl-2 correlated with morphology and differentiation markers with the hierarchy of bcl-2 expression being: N-type cells > N/I-type > I-type > S-type. Furthermore, stimulation of one of the N-type clones, SH-SY5Y, with the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate, induced differentiation toward a more neuronal-like phenotype and resulted in a 5- to 10-fold elevation in the relative levels of Bcl-2 protein. High relative amounts of p26-Bcl-2 protein were also found in an N-type clone derived from the SMS-KCN line. In two N-type clones derived from the LA-N-1 line, however, levels of Bcl-2 protein were only moderately elevated, and in one N-type clone from the SK-N-BE(2) line the levels of Bcl-2 protein were low. Thus, high relative levels of Bcl-2 oncoprotein are not a universal feature of N-type cells (three of six clones tested). In contrast, all 5 of the S-type clones evaluated contained relatively low levels of Bcl-2 protein, suggesting that these cells (which may represent embryonic precursors of Schwann, glial, and melanocytic cells) do not typically express the bcl-2 gene at high levels. Consistent with this inverse correlation between Bcl-2 protein levels and S-type characteristics, stimulation of an I-type clone derived from the SK-N-BE(2) line with 5-bromodeoxyuridine was accompanied by an accumulation of S-type cells in these cultures, decreased Bcl-2 protein, diminutions in the neuronal markers neurofilament-M and neuron-specific enolase, and an increase in the relative levels of the S-type marker proteins vimentin and beta-2-microglobulin. Conversely, stimulation of this I-type clone with retinoic acid resulted in an accumulation of N-type cells (which are thought to represent embryonic precursors of sympathetic neurons), decreased vimentin and beta-2-microglobulin, increased neurofilament-M, and a marked elevation in p26-Bcl-2.(ABSTRACT TRUNCATED AT 400 WORDS)
Hanada
M
M
La Jolla Cancer Research Foundation, Cancer Research Center, California 92037.
Krajewski
S
S
Tanaka
S
S
Cazals-Hatem
D
D
Spengler
B A
BA
Ross
R A
RA
Biedler
J L
JL
Reed
J C
JC
D000970:Antineoplastic Agents / Q000633:toxicity*; D002273:Carcinogens / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002999:Clone Cells; D004351:Drug Resistance; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007700:Kinetics; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology*; D009857:Oncogenes; D010703:Phorbol Esters / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000970:Antineoplastic Agents; D002273:Carcinogens; D010703:Phorbol Esters; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; C008876:phorbol-12,13-didecanoate; D014212:Tretinoin; D013755:Tetradecanoylphorbol Acetate