Nutlin-3 up-regulates the expression of Notch1 in both myeloid and lymphoid leukemic cells, as part of a negative feedback antiapoptotic mechanism.

Abstract

The small molecule inhibitor of the MDM2/p53 interaction Nutlin-3 significantly up-regulated the steady-state mRNA and protein levels of Notch1 in TP53(wild-type) (OCI, SKW6.4) but not in TP53(deleted) (HL-60) or TP53(mutated) (BJAB) leukemic cell lines. A direct demonstration that NOTCH1 was a transcriptional target of p53 in leukemic cells was obtained in experiments carried out with siRNA for p53. Moreover, inhibition of Notch1 expression using Notch1-specific siRNA significantly increased cytotoxicity in TP53(wild-type) leukemic cells. Of note, Nutlin-3 up-regulated Notch1 expression also in primary TP53(wild-type) B-chronic lymphocytic leukemia (B-CLL) cells and the combined use of Nutlin-3 plus pharmacological gamma-secretase inhibitors of the Notch signaling showed a synergistic cytotoxicity in both TP53(wild-type) leukemic cell lines and primary B-CLL cells. A potential drawback of gamma-secretase inhibitors was their ability to enhance osteoclastic maturation of normal circulating preosteoclasts induced by RANKL + M-CSF. Notwithstanding, Nutlin-3 completely suppressed osteoclastogenesis irrespective of the presence of gamma-secretase inhibitors. Taken together, these data indicate that the p53-dependent up-regulation of Notch1 in response to Nutlin-3 represents an antiapoptotic feedback mechanism able to restrain the potential therapeutic efficacy of Nutlin-3 in hematologic malignancies. Therefore, therapeutic combinations of Nutlin-3 + gamma-secretase inhibitors might potentiate the cytotoxicity of Nutlin-3 in p53(wild-type) leukemic cells.

• Authors: Paola Secchiero, Elisabetta Melloni, Maria Grazia di Iasio, Mario Tiribelli, Erika Rimondi, Federica Corallini, Valter Gattei, Giorgio Zauli
• Journal: Blood (Blood) Vol. 113 Issue 18 Pg. 4300-8 (Apr 30 2009) ISSN: 1528-0020 [Electronic] United States
• PMID: 19190243 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carbamates
• Dipeptides
• Imidazoles
• L 685458
• NOTCH1 protein, human
• Piperazines
• RNA, Messenger
• Receptor, Notch1
• TP53 protein, human
• Tumor Suppressor Protein p53
• nutlin 3
• Amyloid Precursor Protein Secretases

Topics

• Adult
• Aged
• Aged, 80 and over
• Amyloid Precursor Protein Secretases (antagonists & inhibitors, metabolism)
• Apoptosis
• Blotting, Western
• Carbamates (pharmacology)
• Cell Differentiation
• Dipeptides (pharmacology)
• Drug Synergism
• Drug Therapy, Combination
• Feedback, Physiological
• Female
• HL-60 Cells
• Humans
• Imidazoles (pharmacology)
• Leukemia, Lymphocytic, Chronic, B-Cell (genetics, metabolism, pathology)
• Male
• Middle Aged
• Osteoclasts (cytology, metabolism)
• Piperazines (pharmacology)
• RNA, Messenger (metabolism)
• Receptor, Notch1 (genetics, metabolism)
• Reverse Transcriptase Polymerase Chain Reaction
• Stereoisomerism
• Tumor Suppressor Protein p53 (antagonists & inhibitors, genetics, metabolism)
• Up-Regulation