Expression and functional analysis of the anaplastic lymphoma kinase (ALK) gene in tumor cell lines

Abstract

The initial identification of the ALK gene, expressed as C-terminal part of the transforming fusion protein NPM-ALK in the t(2;5)(p23;q35) lymphoma-associated chromosomal translocation, revealed a novel receptor tyrosine kinase (RTK). In order to expand the knowledge on ALK expression in the human system, we examined a panel of human cell lines for ALK expression and found that transcription is completely repressed in cell lines of entodermal origin (0/21). Furthermore, full length receptor expression is absent in cell lines of the hematopoietic system with the exception of t(2; 5)-associated anaplastic large cell lymphomas lines (ALCL), which are known to express chimeric NPM-ALK mRNA. Cell lines established from solid tumors of ectodermal origin, including melanoma and breast carcinoma, exhibited widespread mRNA expression of the ALK receptor at a broad range (53/64), an association which was found to be strongest in cell lines derived from neuroblastoma (6/6), glioblastoma (8/8) as well as in cell lines established from Ewing sarcoma (4/4) and retinoblastomas (2/2). Because of the reported involvement of neutrophin tyrosine kinase receptors in autocrine differentiation in neuroblastomas, we analyzed cell lines positive for full length or chimeric ALK protein for the presence of phoshotyrosine residues within the intracellular region of ALK. While the constitutive activation of chimeric NPM-ALK molecules could be shown, no evidence was found for induced or constitutively activated ALK receptors in neuroblastoma, melanoma or breast carcinoma cell lines. Although the receptor could be shown to be consistently expressed with exclusive specificity in tissues developed from the ectoderm, our results do not support any involvement of ALK in the stimulation of tumorigenic cell growth or differentiation so far, indicating that ALK expression is a physiologic rather than a pathologic phenomenon. © 2002 Wiley-Liss, Inc. Key words: receptor tyrosine kinase; ALK, translocation; t(2;5)(p23; q35); ALCL; tumor cell linesThe genesis of lymphoproliferative disorders and of solid tumors is caused in part by chromosomal translocations, when new hybrid genes are generated and the expression of the fusion gene products possess severe oncogenic properties. 1 Anaplastic large cell lymphoma (ALCL) is associated with a (2;5)(p23;q35) chromosomal translocation, 2 which fuses the gene encoding the ALK receptor tyrosine kinase localized at 2p23 with the housekeeping gene nucleophosmin (NPM) at 5q35. 3 The resultant hybrid gene harbors the NH 2 -terminus of NPM linked to the entire intracytoplasmatic portion of ALK encoding a constitutively activated 80 kDa nuclear phosphoprotein, 4 which could be shown to be sufficient for malignant transformation of murine fibroblasts in vitro or for induction of transplantable lymphoma in mice. 5,6 Recently, a number of investigations have shown that genes other than NPM could provide similar structural and functional prerequisites, since different ALK products have been identified in cases of ALCLs as...

Expression and clinical relevance of MET and ALK in Ewing sarcomas

“…Although ALK expression was previously demonstrated in a few ES cell lines and patient samples, these studies lacked the power to accurately determine the frequency of ALK upregulation and its association with patient outcome. 18,19 We demonstrated that MET is ubiquitously expressed in ES. The majority of tumors showed medium to high levels of cytoplasmic MET and apparent membranous staining was detected in several samples as well.…”

“…16,17 In addition, ALK mRNA and/or protein expression was demonstrated in ES cell lines (4/4) and ES tumor samples (6/10), although the sample size was rather small. 18,19 No correlation between ALK expression and clinical outcome has been described in ES at present.…”

Anaplastic lymphoma kinase is expressed in different subtypes of human breast cancer

“…However, ALK was originally discovered when it was found that the chimeric N-terminal nucleophosmin (NPM) domain/cytoplasmic (catalytic) ALK domain fusion protein (NPM-ALK) is the oncoprotein underlying the pathogenesis of anaplastic large cell lymphomas (ALCL) [5,6]. NPM-ALK results from the (2;5) (p23;q35) chromosomal translocation, however, other translocations also lead to constitutive activation of ALK and other malignancies and furthermore, wild-type ALK has been postulated to be involved in the pathogenesis of rhabdomyosarcomas [7], neuroblastoma and neuroectodermal tumors [8,9], glioblastomas [10], and melanomas [11].…”

“…Based on our recent findings that inappropriate expression of Ptn in transgenic mice stimulates breast cancer progression (Chang et al Submitted 2 ), that PTN signaling may be important in breast cancer [22], and that PTN activates the potent oncoprotein ALK through the PTN/ RPTPβ/ζ signaling pathway in PTN-stimulated cells (Perez-Pinera et al 1 ), we explored different databases to learn whether ALK is expressed in human breast cancers; only a single manuscript described ALK expression in breast cancer cell lines using RT-PCR [11]. The significance of the transcripts of ALK detected by PCR is unknown and, in the database search, we failed to uncover that ALK is expressed in human breast cancer tissues.…”

Recruitment of insulin receptor substrate-1 and activation of NF-κB essential for midkine growth signaling through anaplastic lymphoma kinase

“…Full-length ALK was initially described as an orphan receptor tyrosine kinase that shows restricted tissue distribution and is regulated during organ development (Iwahara et al, 1997;Morris et al, 1997). Several studies show expression of full-length ALK protein in cultured fibroblasts and endothelial cells as well as cell lines derived from epithelial cancers such as pancreatic and breast carcinoma (Stoica et al, 2001 and the neuroectoderm, that is, melanoma (Dirks et al, 2002), neuroblastoma Stoica et al, 2002) glioblastoma and non-Hodgkin's lymphoma (Delsol et al, 1997), reviewed by Pulford et al (2004).…”