Suppression of Bcl-2 gene expression by sphingosine in the apoptosis of human leukemic HL-60 cells during phorbol ester-induced terminal differentiation

• Published in: FEBS letters 1996-01, Vol.379 (2), p.177-180
• Main Authors: Sakakura, Chouhei, Sweeney, Elizabeth A., Shirahama, Tsutomu, Hakomori, Sen-itiroh, lgarashi, Yasuyuki
• Format: Article
• Language: English
• Subjects: 1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; 4β-phorbol-12 myristate; Alkaloids - pharmacology; Apoptosis; Bcl-2; bcl-2-Associated X Protein; bcl-X Protein; Cell Differentiation; Differentiation; DMS; DNA, Neoplasm - isolation & purification; Enzyme Inhibitors - pharmacology; Gene Expression - drug effects; HL-60 Cells; Humans; Isoquinolines - pharmacology; Kinetics; N,N-dimethylsphingosine; Phorbol ester (PMA); Piperazines - pharmacology; PKC; PMA; protein kinase C; Protein Kinase C - antagonists & inhibitors; Protein-Tyrosine Kinases - biosynthesis; Proto-Oncogene Proteins - biosynthesis; Proto-Oncogene Proteins c-bcl-2; Proto-Oncogenes; Sph; Sphingosine; Sphingosine - analogs & derivatives; Sphingosine - pharmacology; Staurosporine; Suppression, Genetic; Tetradecanoylphorbol Acetate - pharmacology
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(95)01508-6

Our recent studies have shown that intracellular levels of sphingosine, an endogenous PKC inhibitor, increase during apoptosis resulting from phorbol ester (PMA)-induced terminal differentiation of human myeloid leukemic HL-60 cells, and have suggested that sphingosine may function as an endogenous mediator of apoptosis in these cells [Ohta, et al. (1995) Cancer Res. 55, 691–697]. We report here that apoptosis induced by PMA, sphingosine, and N,N-dimethylsphingosine (DMS) was accompanied by a concomitant decrease of bcl-2 expression in both RNA and protein levels in HL-60 cells, while expression of bcl-X L and bax mRNA did not change, and neither sphingosine nor DMS induced differentiation of HL-60 cells. In contrast, in apoptotic cells induced by pharmaceutical PKC inhibitors H7 or staurosporine, expression of bcl-2 did not change nor did the intracellular sphingosine concentration. These results suggest that sphingosine may function as an endogenous mediator of apoptotic signaling in PMA-induced terminal differentiation of HL-60 cells through bcl-2 down-regulation, probably independent from PKC inhibition.