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SPTBNI-FLT3 in atypical chronic myeloid leukemia transforms Ba/F3 cells to IL-3 independence and is sensitive to both tyrosine kinase inhibitors and immunotherapy

SPTBNI-FLT3 in atypical chronic myeloid leukemia transforms Ba/F3 cells to IL-3 independence and is sensitive to both tyrosine kinase inhibitors and immunotherapy
SPTBNI-FLT3 in atypical chronic myeloid leukemia transforms Ba/F3 cells to IL-3 independence and is sensitive to both tyrosine kinase inhibitors and immunotherapy
We have identified a patient who presented with BCR-ABL negative chronic myeloid leukemia (CML) and an acquired 46XX, t(2;13;2;21) (p13;q12;q33;q11.2) in all bone marrow metaphases examined. Fluorescence in situ hybridization (FISH) using probes flanking the FLT3 gene at 13q12 suggested that this gene was disrupted. 5'-RACE PCR using primers to the region of FLT3 encoding the tyrosine kinase domain identified a novel in-frame mRNA fusion between exon 3 of SPTBN1 (spectrin, beta, non-erythrocytic 1 isoform 2, NM 178313) on chromosome 2p16 and exon 13 of FLT3 (NM 004119). Juxtaposition of SPTBN1 and FLT3 was confirmed by two color FISH and amplification of the genomic DNA breakpoint confirmed a fusion between intron 3 of SPTBN1 and intron 12 of FLT3. The SPTBN1-FLT3 fusion gene is predicted to be translated into a 570 amino acid chimeric protein that retains two coiled-coil domains from SPTBN1 and 424 amino acids from FLT3, including the entire tyrosine kinase domain. Since the t(2;13) is readily visible by cytogenetic analysis but has not been reported previously it seems likely that SPTBN1-FLT3 is uncommon. However to test if FLT3 might be involved more widely in BCR-ABL negative CML we analysed 40 cases by RT-PCR. Two cases were positive for the FLT3 internal tandem duplication (ITD) but mutation of residue D835 was not observed. Expression of the SPTBN1-FLT3 fusion transformed the interleukin 3 (IL-3)-dependent cell line Ba/F3 to growth factor independence and was accompanied by constitutive phosphorylation of the fusion protein and the downstream substrate ERK1/2. The growth of transformed cells was inhibited in a dose-dependent fashion by SU11567 and PKC142, but not by imatinib mesylate. The patient was initially treated with hydroxyurea and subsequently underwent an unrelated donor bone marrow transplant. She relapsed cytogenetically at 4 years but responded to donor lymphocyte infusion (DLI), achieving sustained cytogenetic and molecular (nested RT-PCR) remission. We conclude that SPTBN1-FLT3 is a rare abnormality in BCR-ABL negative CML that is responsive to both targeted signal transduction therapy and immunotherapy by DLI.
0006-4971
p.568A
Grand, Francis H.
89bd846f-638a-4bda-b8a9-8a1989021b31
Iqbal, Sameena
5466a67e-c498-4a61-8f16-7aef3c81f1c9
Zhang, Lingyan
d295dbaf-f3f8-4b19-9842-f761d41376e2
Russell, Nigel H.
c7782520-de9a-41fd-9512-2fbcd26f0401
Chase, Andrew
a40a09c2-3073-4655-ba0b-a802e34914b5
Cross, Nicholas C.P.
f87650da-b908-4a34-b31b-d62c5f186fe4
Grand, Francis H.
89bd846f-638a-4bda-b8a9-8a1989021b31
Iqbal, Sameena
5466a67e-c498-4a61-8f16-7aef3c81f1c9
Zhang, Lingyan
d295dbaf-f3f8-4b19-9842-f761d41376e2
Russell, Nigel H.
c7782520-de9a-41fd-9512-2fbcd26f0401
Chase, Andrew
a40a09c2-3073-4655-ba0b-a802e34914b5
Cross, Nicholas C.P.
f87650da-b908-4a34-b31b-d62c5f186fe4

Grand, Francis H., Iqbal, Sameena, Zhang, Lingyan, Russell, Nigel H., Chase, Andrew and Cross, Nicholas C.P. (2005) SPTBNI-FLT3 in atypical chronic myeloid leukemia transforms Ba/F3 cells to IL-3 independence and is sensitive to both tyrosine kinase inhibitors and immunotherapy. Blood, 106 (11), p.568A.

Record type: Article

Abstract

We have identified a patient who presented with BCR-ABL negative chronic myeloid leukemia (CML) and an acquired 46XX, t(2;13;2;21) (p13;q12;q33;q11.2) in all bone marrow metaphases examined. Fluorescence in situ hybridization (FISH) using probes flanking the FLT3 gene at 13q12 suggested that this gene was disrupted. 5'-RACE PCR using primers to the region of FLT3 encoding the tyrosine kinase domain identified a novel in-frame mRNA fusion between exon 3 of SPTBN1 (spectrin, beta, non-erythrocytic 1 isoform 2, NM 178313) on chromosome 2p16 and exon 13 of FLT3 (NM 004119). Juxtaposition of SPTBN1 and FLT3 was confirmed by two color FISH and amplification of the genomic DNA breakpoint confirmed a fusion between intron 3 of SPTBN1 and intron 12 of FLT3. The SPTBN1-FLT3 fusion gene is predicted to be translated into a 570 amino acid chimeric protein that retains two coiled-coil domains from SPTBN1 and 424 amino acids from FLT3, including the entire tyrosine kinase domain. Since the t(2;13) is readily visible by cytogenetic analysis but has not been reported previously it seems likely that SPTBN1-FLT3 is uncommon. However to test if FLT3 might be involved more widely in BCR-ABL negative CML we analysed 40 cases by RT-PCR. Two cases were positive for the FLT3 internal tandem duplication (ITD) but mutation of residue D835 was not observed. Expression of the SPTBN1-FLT3 fusion transformed the interleukin 3 (IL-3)-dependent cell line Ba/F3 to growth factor independence and was accompanied by constitutive phosphorylation of the fusion protein and the downstream substrate ERK1/2. The growth of transformed cells was inhibited in a dose-dependent fashion by SU11567 and PKC142, but not by imatinib mesylate. The patient was initially treated with hydroxyurea and subsequently underwent an unrelated donor bone marrow transplant. She relapsed cytogenetically at 4 years but responded to donor lymphocyte infusion (DLI), achieving sustained cytogenetic and molecular (nested RT-PCR) remission. We conclude that SPTBN1-FLT3 is a rare abnormality in BCR-ABL negative CML that is responsive to both targeted signal transduction therapy and immunotherapy by DLI.

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More information

Published date: 16 November 2005
Additional Information: ASH Annual Meeting Abstracts, Poster Sessions. Abstract 2009.

Identifiers

Local EPrints ID: 60597
URI: http://eprints.soton.ac.uk/id/eprint/60597
ISSN: 0006-4971
PURE UUID: 6b1eccd7-b154-4a3a-a555-0a3ee4a8c6de
ORCID for Andrew Chase: ORCID iD orcid.org/0000-0001-6617-9953
ORCID for Nicholas C.P. Cross: ORCID iD orcid.org/0000-0001-5481-2555

Catalogue record

Date deposited: 10 Nov 2008
Last modified: 23 Jul 2022 01:49

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Contributors

Author: Francis H. Grand
Author: Sameena Iqbal
Author: Lingyan Zhang
Author: Nigel H. Russell
Author: Andrew Chase ORCID iD

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