CUTLL1, a novel human T-cell lymphoma cell line with t(7;9) rearrangement, aberrant NOTCH1 activation and high sensitivity to γ-secretase inhibitors

Abstract

Activating mutations in NOTCH1 are present in over 50% of human T-cell lymphoblastic leukemia (T-ALL) samples and inhibition of NOTCH1 signaling with c-secretase inhibitors (GSI) has emerged as a potential therapeutic strategy for the treatment of this disease. Here, we report a new human T-cell lymphoma line CUTLL1, which expresses high levels of activated NOTCH1 and is extremely sensitive to c-secretase inhibitors treatment. CUTLL1 cells harbor a t(7;9)(q34;q34) translocation which induces the expression of a TCRB-NOTCH1 fusion transcript encoding a membrane-bound truncated form of the NOTCH1 receptor. GSI treatment of CUTLL1 cells blocked NOTCH1 processing and caused rapid clearance of activated intracellular NOTCH1. Loss of NOTCH1 activity induced a gene expression signature characterized by the downregulation of NOTCH1 target genes such as HES1 and NOTCH3. In contrast with most human T-ALL cell lines with activating mutations in NOTCH1, CUTLL1 cells showed a robust cellular phenotype upon GSI treatment characterized by G1 cell cycle arrest and increased apoptosis. These results show that the CUTLL1 cell line has a strong dependence on NOTCH1 signaling for proliferation and survival and supports that T-ALL patients whose tumors harbor t(7;9) should be included in clinical trials testing the therapeutic efficacy NOTCH1 inhibition with GSIs.

In vitro validation of -secretase inhibitors alone or in combination with other anti-cancer drugs for the treatment of T-cell acute lymphoblastic leukemia

“…8,15,20,21 By flow cytometric analysis of the DNA content of propidium iodide stained cell populations, we confirmed induction of G0/G1 cell cycle arrest after 7 days of GSI treatment in all cell lines that expressed mutant NOTCH1 and displayed a GSI induced proliferation defect (data not shown).…”

“…8,15,[19][20][21] In this study, we have further evaluated the consequences of GSI treatment of T-ALL cell lines, and investigated possible synergism between GSI and other anti-cancer agents.…”

“…8,15,[19][20][21] We, therefore, investigated whether combining GSI with other anti-cancer agents used for T-ALL treatment could offer a therapeutic advantage over single agent therapy.…”

“…8 Several studies confirmed these initial observations and described induction of cell cycle arrest and reduced cell proliferation after treating sensitive NOTCH1 mutationpositive T-ALL cell lines for several days with GSI. 15,[19][20][21] In this work, we further document the short-and long-term effects of GSI on the growth of T-ALL cell lines and tested whether combinations of GSI with other anti-cancer agents could offer any therapeutic advantage over single agent therapy.…”

NOTCH mutations as prognostic markers in T-ALL

“…[2][3][4][5] Moreover, anti-NOTCH1 therapies hold the promise of providing a molecularly tailored treatment for this disease. 2,6 Early studies on the prognostic significance of NOTCH activation in T-ALL showed that NOTCH1 mutations are not associated with poor outcome and suggested that in fact they could be associated with good prognosis. Thus, an original study comprising 157 pediatric T-ALL patients from the pediatric ALL-BFM 2000 study found that NOTCH1 mutations were associated with low levels of MRD and improved relapse-free survival.…”