title: Gamma-secretase inhibitors suppress the growth of leukemia and lymphoma cells.
abstract: gamma-Secretase inhibitors (GSI) suppress the growth of acute T-lymphoblastic leukemia (T-ALL) cells with NOTCH1 mutations. Recently, clinical trials of GSI for refractory T-ALL have commenced. In the present study, we examined the effects of three types of GSI; GSI-I, GSI-IX, and GSI-XII on the growth of four B-cell malignant lymphoma (B-ML) and four acute myeloid leukemia (AML) cell lines as well as four T-ALL cell lines. We found that GSI also suppressed the in vitro growth of some B-ML and AML cell lines in a dose-dependent manner. Growth suppression occurred through induction of apoptosis. Expression of the HES1 gene, one of the targets of Notch signaling, was high in T-ALL cells with NOTCH1 mutations, but was low in GSI-sensitive B-ML and AML cells. GSI treatment decreased HES1 mRNA expression in T-ALL cells, while GSI increased HES1 mRNA in two GSI-sensitive B-ML and AML cell lines. In immunoblot analysis, the band for the intracellular fragment of Notch1, an active form of Notch1, was dense in T-ALL cells but was faint in GSI-sensitive B-ML and AML cells; attenuation of the band by GSI was not evident. These findings suggest that GSI may act on Notch 2, 3 or 4 protein, or some pathways other than Notch signaling in GSI-sensitive B-ML and AML cells. Namely, growth suppression by GSI may involve cell growth-related proteins, which are gamma-secretase substrates. Taken together, we have shown that GSI may be useful for the treatment of hematological malignancies other than T-ALL. The mechanism behind the effects remains to be clarified. Our investigations lead to a novel molecular target therapy for chemotherapy-resistant leukemia and lymphomas.
authors.affiliation: Department of Laboratory Medicine, Tokyo Medical and Dental University, Tokyo 113-8519, Japan.
authors.forename: Hanae
authors.initials: H
authors.lastname: Kogoshi
authors.forename: Taku
authors.initials: T
authors.lastname: Sato
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Koyama
authors.forename: Nobuo
authors.initials: N
authors.lastname: Nara
authors.forename: Shuji
authors.initials: S
authors.lastname: Tohda
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D016393:Lymphoma, B-Cell / Q000188:drug therapy* / Q000378:metabolism; D016403:Lymphoma, Large B-Cell, Diffuse / Q000188:drug therapy / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D004791:Enzyme Inhibitors; D051880:Receptors, Notch; D053829:Amyloid Precursor Protein Secretases