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Immunoglobulin heavy chain locus events and expression of activation-induced cytidine deaminase in epithelial breast cancer cell lines

Immunoglobulin heavy chain locus events and expression of activation-induced cytidine deaminase in epithelial breast cancer cell lines
Immunoglobulin heavy chain locus events and expression of activation-induced cytidine deaminase in epithelial breast cancer cell lines
When cells transform, phenotypic and genetic profiles can be dramatically altered. Nevertheless, a recent report identifying IgG in breast cancer cells was unexpected, revealing differentiation features normally associated with B lymphocytes. To extend these findings, we focused on immunoglobulin variable (V) region gene analysis using well-defined breast cancer cell lines expressing the epithelial marker, epithelial cell adhesion molecule (EpCAM). VH gene transcripts were identifiable by nested reverse transcription-PCR either as single or dual V, diversity (D), and joining (J) rearrangements in four of six lines, most being potentially functional. V(D)J transcripts were observed in sequential cultures, indicating stable expression. To exclude coexisting lymphocytes, each cell line was shown to be EBV negative, with CD19/CD20 and cytoplasmic/surface immunoglobulin also absent by flow cytometry. Identified VH transcripts were then sought in individual tumor cells, isolated as EpCAM+ single cells by flow cytometry. Importantly, in three of three selected cell lines, VH genes were identifiable in a significant fraction (~32%) of single cells. In five of six identified VH genes, somatic mutations were apparent with no intraclonal variation, indicating cessation of mutational activity. VH transcripts were pre- and post-isotype switch, with activation of switch events evident from expressed germ-line switch transcripts in two of six lines. Strikingly, six of six cell lines expressed activation-induced cytidine deaminase (AID) essential for mutational and switch activity. These data suggest either a de novo rearrangement and modification of VH genes in epithelial tumor cells or assimilation of lymphocyte-derived chromatin. Constitutive AID activation in malignant epithelial cells further raises a potential for inducing aberrant mutational activity.
mechanism, expression, hypermutation, cells, mutations, gene, aid, cancer, lymphoma, class switch recombination, breast cancer, region, activation, dna
0008-5472
3996-4000
Babbage, Gavin
d2036377-f36a-4a4a-8634-4b0394dffe28
Ottensmeier, Christian H.
42b8a398-baac-4843-a3d6-056225675797
Blaydes, Jeremy
e957f999-fd91-4f77-ad62-5b4ef069b15b
Stevenson, Freda K.
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Sahota, Surinder S.
66c1457f-cba2-4c49-9c8c-fcee0748b6b8
Babbage, Gavin
d2036377-f36a-4a4a-8634-4b0394dffe28
Ottensmeier, Christian H.
42b8a398-baac-4843-a3d6-056225675797
Blaydes, Jeremy
e957f999-fd91-4f77-ad62-5b4ef069b15b
Stevenson, Freda K.
ba803747-c0ac-409f-a9c2-b61fde009f8c
Sahota, Surinder S.
66c1457f-cba2-4c49-9c8c-fcee0748b6b8

Babbage, Gavin, Ottensmeier, Christian H., Blaydes, Jeremy, Stevenson, Freda K. and Sahota, Surinder S. (2006) Immunoglobulin heavy chain locus events and expression of activation-induced cytidine deaminase in epithelial breast cancer cell lines. Cancer Research, 66 (8), 3996-4000. (doi:10.1158/0008-5472.CAN-05-3704).

Record type: Article

Abstract

When cells transform, phenotypic and genetic profiles can be dramatically altered. Nevertheless, a recent report identifying IgG in breast cancer cells was unexpected, revealing differentiation features normally associated with B lymphocytes. To extend these findings, we focused on immunoglobulin variable (V) region gene analysis using well-defined breast cancer cell lines expressing the epithelial marker, epithelial cell adhesion molecule (EpCAM). VH gene transcripts were identifiable by nested reverse transcription-PCR either as single or dual V, diversity (D), and joining (J) rearrangements in four of six lines, most being potentially functional. V(D)J transcripts were observed in sequential cultures, indicating stable expression. To exclude coexisting lymphocytes, each cell line was shown to be EBV negative, with CD19/CD20 and cytoplasmic/surface immunoglobulin also absent by flow cytometry. Identified VH transcripts were then sought in individual tumor cells, isolated as EpCAM+ single cells by flow cytometry. Importantly, in three of three selected cell lines, VH genes were identifiable in a significant fraction (~32%) of single cells. In five of six identified VH genes, somatic mutations were apparent with no intraclonal variation, indicating cessation of mutational activity. VH transcripts were pre- and post-isotype switch, with activation of switch events evident from expressed germ-line switch transcripts in two of six lines. Strikingly, six of six cell lines expressed activation-induced cytidine deaminase (AID) essential for mutational and switch activity. These data suggest either a de novo rearrangement and modification of VH genes in epithelial tumor cells or assimilation of lymphocyte-derived chromatin. Constitutive AID activation in malignant epithelial cells further raises a potential for inducing aberrant mutational activity.

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Published date: 15 April 2006
Keywords: mechanism, expression, hypermutation, cells, mutations, gene, aid, cancer, lymphoma, class switch recombination, breast cancer, region, activation, dna

Identifiers

Local EPrints ID: 40684
URI: http://eprints.soton.ac.uk/id/eprint/40684
ISSN: 0008-5472
PURE UUID: 6408d8d8-2cd7-4556-add3-47290122aaa4
ORCID for Jeremy Blaydes: ORCID iD orcid.org/0000-0001-8525-0209
ORCID for Freda K. Stevenson: ORCID iD orcid.org/0000-0002-0933-5021

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Date deposited: 07 Jul 2006
Last modified: 17 Dec 2019 01:57

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Author: Gavin Babbage
Author: Jeremy Blaydes ORCID iD

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