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At least 19 recordsLinked to original sources
PubMed2006

Design and synthesis of 5-aryl-pyridone-carboxamides as inhibitors of anaplastic lymphoma kinase.

Anaplastic lymphoma kinase (ALK) is a promising new target for therapy of certain cancers such as anaplastic large-cell lymphoma (ALCL) and inflammatory myofibroblastic tumor (IMT). We have identified a series of novel pyridones as kinase inhibitors of ALK by application of a stepwise process involving in vitro screening of a novel targeted library followed by iterative template modification based on medicinal chemistry insights and computational ranking of virtual libraries. Using this process, we discovered ALK-selective inhibitors with improved potency and selectivity. Herein the details of the design process and synthesis of these novel pyridones, along with their enzymatic and cell-based activity, are discussed.

Amides↗
PubMed2006

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

Anaplastic lymphoma kinase (ALK) is a transmembrane receptor tyrosine kinase in the insulin receptor superfamily. We recently demonstrated that the growth factors pleiotrophin (PTN) and midkine (MK) are ligands for ALK and that upon ALK activation, insulin receptor substrate-1 (IRS-1) and other substrates are phosphorylated. Here, the role of IRS-1 in ligand-mediated ALK signaling is investigated in interleukin-3 (IL-3)-dependent 32D murine myeloid cells. These cells do not express ALK and IRS family members, and do not respond to exogenously added PTN or MK. We show that expression of ALK plus IRS-1 renders these cells independent of IL-3 owing to the activation of ALK by endogenous MK. Mutational analysis reveals that this transformed phenotype of 32D cells requires kinase-active ALK as well as the interaction of ALK with IRS-1. Furthermore, 32D/IRS-1/ALK cells display an enhanced activation of mitogen-activated protein kinase and PI3-kinase pathways, and a selective transcriptional activation of nuclear factor (NF)-kappaB. Small interfering RNA-mediated knockdown of the endogenous MK or p65/NF-kappaB revealed that both these are rate limiting for the transformed phenotype induced by ALK plus IRS-1. We conclude that the recruitment of IRS-1 to activated ALK and the activation of NF-kappaB are essential for the autocrine growth and survival signaling of MK.

Anaplastic Lymphoma Kinase↗
PubMed2004

The emerging normal and disease-related roles of anaplastic lymphoma kinase.

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase, the normal role of which remains to be completely elucidated. Although work carried out in mammals suggests a function in neural development, results from studies in Drosophila indicate an additional role in visceral muscle differentiation. The aberrant expression of full-length ALK receptor proteins has been reported in neuroblastomas and glioblastomas, while the occurrence of ALK fusion proteins in anaplastic large cell lymphoma (ALCL) has resulted in the identification of the new tumor entity, ALK-positive ALCL. ALK represents one of few examples of a receptor tyrosine kinase implicated in oncogenesis in both haematopoietic and non-haematopoietic tumors, given that ALK fusions also occur in the mesenchymal tumor known as inflammatory myofibroblastic tumor (IMT). The study of ALK fusion proteins, besides demonstrating their importance in tumor development, has also raised the possibility of new therapeutic treatments for patients with ALK-positive malignancies.

Adenoviridae↗
PubMed2003

Nucleophosmin-anaplastic lymphoma kinase of anaplastic large-cell lymphoma recruits, activates, and uses pp60c-src to mediate its mitogenicity.

Anaplastic large-cell lymphomas (ALCLs) are lymphomas of T or null phenotype often associated with a chromosomal translocation, t(2;5)(p23;q35). This translocation leads to the expression of a hybrid protein consisting of the N-terminal portion of nucleophosmin (NPM) and the intracellular domain of the anaplastic lymphoma kinase (ALK). NPM-ALK possesses a constitutive tyrosine kinase activity responsible for its oncogenic property through activation of downstream effectors such as phospholipase C gamma (PLC-gamma) and the type IA phosphoinositide 3-kinase. Here, we show that the Src-kinases, particularly pp60(c-src), associate with and are activated by NPM-ALK expression in various cells, and in cell lines established from patients with ALCL. The kinase activity and the tyrosine 418 of NPM-ALK are required for its association with Src-kinases. Y418F mutation of NPM-ALK impaired its association with Src-kinases and strongly reduced the proliferation rate of Ba/F3 cells. In agreement, Src-kinase inhibitors or pp60(c-src) siRNA significantly decreased the proliferation rate of NPM-ALK-positive ALCL cell lines. Moreover, using active or inactive forms of pp60(c-src) and NPM-ALK, we provide evidence that NPM-ALK is a potential substrate of pp60(c-src). Overall, our data place Src-kinases as new important downstream effectors of NPM-ALK and as attractive potential therapeutic targets for new ALCL treatment.

Anaplastic Lymphoma Kinase↗
PubMed2002

Identification of novel fusion partners of ALK, the anaplastic lymphoma kinase, in anaplastic large-cell lymphoma and inflammatory myofibroblastic tumor.

ALK-positive anaplastic large-cell lymphoma (ALCL) has been recognized as a distinct type of lymphoma in the heterogeneous group of T/Null-ALCL. While most of the ALK-positive ALCL (ALKomas) are characterized by the presence of the NPM-ALK fusion protein, the product of the t(2;5)(p23;q35), 10-20% of ALKomas contain variant ALK fusions, including ATIC-ALK, TFG-ALK, CLTC-ALK (previously designated CLTCL-ALK), TMP3-ALK, and MSN-ALK. TMP3-ALK and TMP4-ALK fusions also have been detected in inflammatory myofibroblastic tumors (IMTs), making clear that aberrations of the ALK gene are not associated exclusively with the pathogenesis of ALK-positive ALCL. Here we report results of molecular studies on two lymphoma cases and one IMT case with variant rearrangements of ALK. Our study led to the detection of the CLTC-ALK fusion in an ALCL case and to the identification of two novel fusion partners of ALK: ALO17 (KIAA1618), a gene with unknown function, which was fused to ALK in an ALCL case with a t(2;17)(p23;q25), and CARS, encoding the cysteinyl-tRNA synthetase, which was fused to ALK in an IMT case with a t(2;11;2)(p23;p15;q31). These results confirm the recurrent involvement of ALK in IMT and further demonstrate the diversity of ALK fusion partners, with the ability to homodimerize as a common characteristic.

Abdomen↗
PubMed2004

A case of primary cutaneous anaplastic large cell lymphoma with variant anaplastic lymphoma kinase translocation.

Anaplastic lymphoma kinase (ALK) is frequently observed in systemic anaplastic large cell lymphoma (ALCL), mostly in childhood or adolescence, but only rarely in primary cutaneous cases. We report a case of primary cutaneous ALCL (pcALCL) with cytoplasmic ALK expression. A 54-year-old woman with an ulcerative tumour on her forehead was admitted to our hospital. Histologically, there was an infiltrate consisting of atypical large lymphocytes and small lymphocytes in the dermis and fat tissue. Southern blot analysis showed monoclonal T-cell receptor Cbeta1 gene rearrangement. Atypical large lymphocytes were positive for CD30, CD4 and CD25, and negative for CD3 and CD79a. They were also positive for ALK only in the cytoplasm, and neurophosmin (NPM)-ALK fusion transcript was not detected by reverse transcription-polymerase chain reaction. This suggested that the translocation partner of the ALK gene in this case was different from NPM (variant translocation). The tumour on the forehead resolved in 1 month after biopsy. Nodular lesions recurred on the right knee, and were histologically identical with the forehead lesion. Our case suggests the existence of a subgroup with variant ALK translocation in pcALCL; examining NPM-ALK translocation in each case with ALK expression should be useful to characterize the disease further.

Anaplastic Lymphoma Kinase↗
PubMed2006

Cutaneous presentation on the eyelid of primary, systemic, CD30+, anaplastic lymphoma kinase (ALK)-negative, anaplastic large-cell lymphoma (ALCL).

AIM: To report an unusual case of cutaneous presentation on the eyelid of systemic (or nodal), CD30+, anaplastic large-cell lymphoma (ALCL). METHODS: A 39-year-old man presented with a rapidly growing exophytic mass on the left upper eyelid, with a protuberant, ulcerated aspect and with discharge. The patient showed lymph node involvement 3 months after the appearance of the lesion on the eyelid (the lesion itself appeared 1 week before examination). RESULTS: The histopathologic and immunohistochemical diagnosis was ALCL, T-cell phenotype, strongly positive for CD43 and CD30, and negative for CD3, anaplastic lymphoma kinase (ALK), and B-cell antigens. Treatment was by radiotherapy and, later, chemotherapy (cyclophosphamide, adriamycin, vincristine, and prednisolone, CHOP) for skin recurrences and lymphadenopathies over 5 years. There has been no recurrence for more than 6 years. CONCLUSIONS: Primary, systemic, CD30+, ALK-negative, ALCL presentations generally have a poor prognosis and tend to occur in older individuals, although the clinical outcome is highly variable and difficult to predict in individual cases. Only three cases of ALCL have been described in the ocular adnexae and none was ALK-negative.

Adult↗
PubMed2000

Nucleophosmin-anaplastic lymphoma kinase associated with anaplastic large-cell lymphoma activates the phosphatidylinositol 3-kinase/Akt antiapoptotic signaling pathway.

More than half of anaplastic large-cell lymphomas (ALCLs) have a chromosomal translocation t(2;5) that leads to the expression of a hybrid protein composed of the nucleolar phosphoprotein nucleophosmin (NPM) and the anaplastic lymphoma kinase (ALK) that exhibits an unregulated tyrosine kinase activity. We have previously identified PLC-gamma as a crucial downstream signaling molecule of NPM-ALK that contributes to its mitogenic potential. Here, we show that NPM-ALK recruits the C-terminal SH2 domain of the phosphatidylinositol 3-kinase (PI 3kinase) p85 subunit. PI 3-kinase assays revealed that the kinase is activated by NPM-ALK in vivo, in turn activating PKB/Akt in NPM-ALK-expressing cells. The use of 2 specific PI 3-kinase inhibitors, wortmannin and LY294002, demonstrated the requirement of PI 3-kinase for the growth of NPM-ALK-transformed cell lines, as well as a cell line established from a patient with ALCL. Primary murine bone marrow retrovirally transduced with NPM-ALK showed a transformed phenotype that was reversible on treatment with PI 3-kinase inhibitors. Flow cytometric analysis revealed that wortmannin-treated NPM-ALK-transformed cell lines underwent apoptosis. Furthermore, apoptosis induced by overexpression of the proapoptotic molecule Bad could be partially blocked by the overexpression of NPM-ALK. Thus, NPM-ALK activates the antiapoptotic PI 3-kinase/Akt pathway, which likely contributes to the molecular pathogenesis of ALCL. (Blood. 2000;96:4319-4327)

Amino Acid Substitution↗
PubMed2006

In vivo T-cell immune response against anaplastic lymphoma kinase in patients with anaplastic large cell lymphomas.

BACKGROUND AND OBJECTIVES: Anaplastic lymphoma kinase (ALK) oncogenic fusion proteins, expressed in about 60% of anaplastic large cell lymphomas (ALCL), are tumor-specific molecular targets for such a malignancy. One of the promising ALK-targeted therapeutic options is cancer vaccination. In this study, we investigate whether ALK is a tumor-associated antigen suitable for immune interventions. DESIGN AND METHODS: The frequency and the functional phenotype of the anti-ALK CD8 precursor repertoire in freshly isolated peripheral blood mononuclear cells (PBMC) from healthy donors and ALK-positive patients were determined by major histocompatibility complex (MHC)/tetrameric analyses. The anti-ALK secondary immune responses were evaluated as PBMC-specific interferon (INF-gamma) release by ELISPOT. In addition, the ability of the anti-ALK immune response to specifically lyse ALK-positive lymphoma cells was investigated by in vitro stimulation with ALK-derived peptide p280-89. RESULTS: Tetrameric MHC/peptide complexes revealed high frequencies of CD8/ALK-tetramer-positive cells both in patients and in healthy individuals. However, the functional phenotype of the CD8/ALK-tetramer-positive lymphocytes showed the presence of effector and memory T lymphocytes only in patients. The anti-ALK cytotoxic T lymphocytes (CTL) of patients, but not healthy donors, displayed thresholds of activation comparable to those of CTL precursors of a recall antigen (influenza virus). A polyclonal ALK-specific tumor-reactive T-cell line was isolated from patients' peripheral blood lymphocytes. INTERPRETATION AND CONCLUSIONS: The presence of an anti-ALK effector/memory lymphocyte population in the peripheral blood of ALK-positive patients indicates an in vivo antigenic challenge. Thus, ALK is a lymphoma-associated antigen suitable for immune interventions. The high number of anti-ALK memory CD8 T cells present in patients' PBMC may represent a valid source of activated CTL suitable for cancer cell lysis.

Anaplastic Lymphoma Kinase↗
PubMed2003

Identification and characterization of a nuclear interacting partner of anaplastic lymphoma kinase (NIPA).

Anaplastic large-cell lymphoma is a subtype of non-Hodgkin lymphomas characterized by the expression of CD30. More than half of these lymphomas carry a chromosomal translocation t(2;5) leading to expression of the oncogenic tyrosine kinase nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). NPM-ALK is capable of transforming fibroblasts and lymphocytes in vitro and of causing lymphomas in mice. Previously, we and others demonstrated phospholipase C-gamma and phosphatidylinositol 3-kinase as crucial downstream signaling mediators of NPM-ALK-induced oncogenicity. In this study, we used an ALK fusion protein as bait in a yeast two-hybrid screen identifying NIPA (nuclear interacting partner of ALK) as a novel downstream target of NPM-ALK. NIPA encodes a 60-kDa protein that is expressed in a broad range of human tissues and contains a classical nuclear translocation signal in its C terminus, which directs its nuclear localization. NIPA interacts with NPM-ALK and other ALK fusions in a tyrosine kinase-dependent manner and is phosphorylated in NPM-ALK-expressing cells on tyrosine and serine residues with serine 354 as a major phosphorylation site. Overexpression of NIPA in Ba/F3 cells was able to protect from apoptosis induced by IL-3 withdrawal. Mutations of the nuclear translocation signal or the Ser-354 phosphorylation site impaired the antiapoptotic function of NIPA. In NPM-ALK-transformed Ba/F3 cells, apoptosis triggered by wortmannin treatment was enhanced by overexpression of putative dominant-negative NIPA mutants. These results implicate an antiapoptotic role for NIPA in NPM-ALK-mediated signaling events.

Active Transport, Cell Nucleus↗
PubMed2003

Inhibition of JAK3 induces apoptosis and decreases anaplastic lymphoma kinase activity in anaplastic large cell lymphoma.

Signal transducer and activator of transcription 3 (STAT3), normally activated by Janus kinase (JAK) in response to cytokine stimulation, has been shown to have oncogenic potential. In addition to JAK, recent data suggest that STAT3 can also be activated by other proteins such as the aberrant fusion protein, NPM-ALK, which is expressed in a subset of systemic anaplastic large cell lymphoma (ALCL). In this study, we investigated the possible role of JAK in activating STAT3 in ALCL using two ALK-positive ALCL cell lines, Karpas 299 and SU-DHL-1. At the steady state, JAK3 showed detectable tyrosine phosphorylation by immunoprecipitation. Treatment with AG490, a JAK inhibitor, decreased but did not completely abrogate tyrosine phosphorylation of JAK3 and STAT3 in a concentration-dependent manner. Similar results were obtained using two other inhibitors of JAK3, WHI-P131 and WHI-P154. These biochemical changes were associated with apoptosis in both cell lines that was coupled with activation of caspase 3 and decreased bcl-xL and bcl-2. Cell cycle analysis revealed a decrease in the S phase, which may be attributed to cyclin D3 downregulation and p21(waf1) upregulation. Importantly, the tyrosine kinase activity of NPM-ALK, as assessed by an in vitro assay, decreased with increasing concentrations of AG490. Our findings highlight the importance of JAK3 in activating STAT3 in ALCL, and that NPM-ALK-mediated activation of STAT3 is influenced by the functional status of JAK3.

Anaplastic Lymphoma Kinase↗
PubMed2001

Translocations involving anaplastic lymphoma kinase (ALK).

Anaplastic large-cell lymphoma (ALCL) comprises a group of non-Hodgkin's lymphomas (NHLs) that were first described in 1985 by Stein and co-workers and are characterized by the expression of the CD30/Ki-1 antigen (Stein et al., 1985). Approximately half of these lymphomas are associated with a typical chromosomal translocation, t(2;5)(p23;q35). Much confusion about the exact classification and clinicopathological features of this subgroup of NHL was clarified with the identification of NPM-ALK (nucleophosmin-anaplastic lymphoma kinase) as the oncogene created by the t(2;5) (Morris et al., 1994). With the discovery of NPM-ALK as the specific lymphoma gene mutation, this NHL subtype could be redefined on the molecular level. This achievement was enhanced by the availability of specific antibodies that recognize ALK fusion proteins in paraffin-embedded lymphoma tissues. Several excellent recent reviews have summarized the histopathological and molecular findings of ALCL and their use in the classification of this lymphoma entity (Anagnostopoulos and Stein, 2000; Benharroch et al., 1998; Drexler et al., 2000; Foss et al., 2000; Gogusev and Nezelof, 1998; Kadin and Morris, 1998; Ladanyi, 1997; Morris et al., 2001; Shiota and Mori, 1996; Skinnider et al., 1999; Stein et al., 2000). This review will focus on the molecular function and signal transduction pathways activated by ALK fusion oncogenes, with recent advances and possible clinical implications to be discussed.

Amino Acid Sequence↗
PubMed2006

Anaplastic lymphoma kinase is dynamically expressed on subsets of motor neurons and in the peripheral nervous system.

During embryonic development, complex events, such as cellular proliferation, differentiation, survival, and guidance of axons, are orchestrated and regulated by a variety of extracellular signals. Receptor tyrosine kinases mediate many of these events, with several playing critical roles in neuronal survival and axonal guidance. It is evident that not all the receptor tyrosine kinases that play key roles in regulating neuronal development have been identified. In this study, we have characterized the spatial-temporal expression profile of a recently identified receptor tyrosine kinase, anaplastic lymphoma kinase (ALK), in embryonic chick by means of whole-mount in situ hybridization in conjunction with immunohistochemistry. Our findings reveal that Alk is expressed in sympathetic and dorsal root ganglia as early as stage 19. In addition, mRNA is expressed from stage 23/24 (E4) to stage 39 (E13) in discrete motor neuron subsets of chick spinal cord along with a select group of muscles that are innervated by one of these particular motor neuron clusters. Expression within the spinal cord is coincident with the onset and duration of motor neuron programmed cell death and during the period of musculature innervation and synapse formation. Hence, the data presented here identify ALK as a novel candidate receptor for regulating critical events in the development of neurons in both the central and the peripheral nervous systems.

Anaplastic Lymphoma Kinase↗
PubMed2001

Identification of anaplastic lymphoma kinase as a receptor for the growth factor pleiotrophin.

Pleiotrophin (PTN) is a secreted growth factor that induces neurite outgrowth and is mitogenic for fibroblasts, epithelial, and endothelial cells. During tumor growth PTN can serve as an angiogenic factor and drive tumor invasion and metastasis. To identify a receptor for PTN, we panned a phage display human cDNA library against immobilized PTN protein as a bait. From this we isolated a phage insert that was homologous to an amino acid sequence stretch in the extracellular domain (ECD) of the orphan receptor tyrosine kinase anaplastic lymphoma kinase (ALK). In parallel with PTN, ALK is highly expressed during perinatal development of the nervous system and down-modulated in the adult. Here we show in cell-free assays as well as in radioligand receptor binding studies in intact cells that PTN binds to the ALK ECD with an apparent Kd of 32 +/- 9 pm. This receptor binding is inhibited by an excess of PTN, by the ALK ECD, and by anti-PTN and anti-ECD antibodies. PTN added to ALK-expressing cells induces phosphorylation of both ALK and of the downstream effector molecules IRS-1, Shc, phospholipase C-gamma, and phosphatidylinositol 3-kinase. Furthermore, the growth stimulatory effect of PTN on different cell lines in culture coincides with the endogenous expression of ALK mRNA, and the effect of PTN is enhanced by ALK overexpression. From this we conclude that ALK is a receptor that transduces PTN-mediated signals and propose that the PTN-ALK axis can play a significant role during development and during disease processes.

Adrenal Gland Neoplasms↗
PubMed2005

Biological role of anaplastic lymphoma kinase in neuroblastoma.

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase receptor originally identified as part of the chimeric nucleophosmin-ALK protein in the t(2;5) chromosomal rearrangement associated with anaplastic large cell lymphoma. We recently demonstrated that the ALK kinase is constitutively activated by gene amplification at the ALK locus in several neuroblastoma cell lines. Forming a stable complex with hyperphosphorylated ShcC, activated ALK modifies the responsiveness of the mitogen-activated protein kinase pathway to growth factors. In the present study, the biological role of activated ALK was examined by suppressing the expression of ALK kinase in neuroblastoma cell lines using an RNA interference technique. The suppression of activated ALK in neuroblastoma cells by RNA interference significantly reduced the phosphorylation of ShcC, mitogen-activated protein kinases, and Akt, inducing rapid apoptosis in the cells. By immunohistochemical analysis, the cytoplasmic expression of ALK was detected in most of the samples of neuroblastoma tissues regardless of the stage of the tumor, whereas significant amplification of ALK was observed in only 1 of 85 cases of human neuroblastoma samples. These data demonstrate the limited frequency of ALK activation in the real progression of neuroblastoma.

Anaplastic Lymphoma Kinase↗
PubMed2006

[Expression of anaplastic lymphoma kinase and survivin proteins in anaplastic large cell lymphoma and its significance].

OBJECTIVE: To study the expression of anaplastic lymphoma kinase (ALK) and survivin proteins in anaplastic large cell lymphoma (ALCL) and there clinical significance. METHODS: The morphologic characteristics were studied by routine light microscopy. Immunohistochemical staining for ALK and survivin proteins was performed using LSAB method. RESULTS: ALK protein was positive in 51 cases (63%) and negative in 30 cases (37%) of the 81 cases of ALCL studied. The prognosis of patients with ALK protein expression was better than those without ALK expression (P < 0.05). As for survivin protein, there were various degrees of expression in all the 77 ALCL cases studied. High level of survivin protein expression was observed in 33 cases (42.9%), while low level of expression was seen in 44 cases (57.1%). The expression of survivin protein did not correlate with that of ALK protein (P > 0.05). The survival rate was significantly lower in patients with high survivin protein expression (P < 0.05). In cases with ALK protein expression, the prognosis was less favorable if there was also high co-expression of survivin protein (P < 0.05). In ALK protein negative cases, prognosis did not significantly correlate with the expression of survivin protein (P > 0.05). In addition, multivariate analysis confirmed the prognosis value of ALK protein expression, survivin protein expression and constitutional symptoms. CONCLUSION: Survivin protein expression can serve as an independent prognostic predictor of unfavorable clinical outcome in patients with ALCL, especially when ALK protein is positive.

Adolescent↗
PubMed1998

Nucleophosmin-anaplastic lymphoma kinase of large-cell anaplastic lymphoma is a constitutively active tyrosine kinase that utilizes phospholipase C-gamma to mediate its mitogenicity.

Large-cell anaplastic lymphoma is a subtype of non-Hodgkin's lymphoma characterized by the expression of CD30. More than half of these lymphomas have a chromosomal translocation, t(2;5), that leads to the expression of a hybrid protein comprised of the nucleolar phosphoprotein nucleophosmin (NPM) and the anaplastic lymphoma kinase (ALK). Here we show that transfection of the constitutively active tyrosine kinase NPM-ALK into Ba/F3 and Rat-1 cells leads to a transformed phenotype. Oncogenic tyrosine kinases transform cells by activating the mitogenic signal transduction pathways, e.g., by binding and activating SH2-containing signaling molecules. We found that NPM-ALK binds most specifically to the SH2 domains of phospholipase C-gamma (PLC-gamma) in vitro. Furthermore, we showed complex formation of NPM-ALK and PLC-gamma in vivo by coimmunoprecipitation experiments in large-cell anaplastic lymphoma cells. This complex formation leads to the tyrosine phosphorylation and activation of PLC-gamma, which can be corroborated by enhanced production of inositol phosphates (IPs) in NPM-ALK-expressing cells. By phosphopeptide competition experiments, we were able to identify the tyrosine residue on NPM-ALK responsible for interaction with PLC-gamma as Y664. Using site-directed mutagenesis, we constructed a comprehensive panel of tyrosine-to-phenylalanine NPM-ALK mutants, including NPM-ALK(Y664F). NPM-ALK(Y664F), when transfected into Ba/F3 cells, no longer forms complexes with PLC-gamma or leads to PLC-gamma phosphorylation and activation, as confirmed by low IP levels in these cells. Most interestingly, Ba/F3 and Rat-1 cells expressing NPM-ALK(Y664F) also show a biological phenotype in that they are not stably transformed. Overexpression of PLC-gamma can partially rescue the proliferative response of Ba/F3 cells to the NPM-ALK(Y664F) mutant. Thus, PLC-gamma is an important downstream target of NPM-ALK that contributes to its mitogenic activity and is likely to be important in the molecular pathogenesis of large-cell anaplastic lymphomas.

Animals↗