The tyrosine phosphatase Shp2 interacts with NPM-ALK and regulates anaplastic lymphoma cell growth and migration

Anaplastic large cell lymphomas (ALCL) are mainly characterized by the reciprocal translocation t(2;5)(p23;q35) that involves the anaplastic lymphoma kinase (ALK) gene and generates the fusion protein NPM-ALK with intrinsic tyrosine kinase activity. NPM-ALK triggers several signaling cascades, leading to increased cell growth, resistance to apoptosis, and changes in morphology and migration of transformed cells. To search for new NPM-ALK interacting molecules, we developed a mass spectrometry-based proteomic approach in HEK293 cells expressing an inducible NPM-ALK and identified the tyrosine phosphatase Shp2 as a candidate substrate. We found that NPM-ALK was able to bind Shp2 in coprecipitation experiments and to induce its phosphorylation in the tyrosine residues Y542 and Y580 both in HEK293 cells and ALCL cell lines. In primary lymphomas, antibodies against the phosphorylated tyrosine Y542 of Shp2 mainly stained ALK-positive cells. In ALCL cell lines, Shp2-constitutive phosphorylation was dependent on NPM-ALK, as it significantly decreased after short hairpin RNA (shRNA)-mediated NPM-ALK knock down. In addition, only the constitutively active NPM-ALK, but not the kinase dead NPM-ALK(K210R), formed a complex with Shp2, Gab2, and growth factor receptor binding protein 2 (Grb2), where Grb2 bound to the phosphorylated Shp2 through its SH2 domain. Shp2 knock down by specific shRNA decreased the phosphorylation of extracellular signal-regulated kinase 1/2 and of the tyrosine residue Y416 in the activation loop of Src, resulting in impaired ALCL cell proliferation and growth disadvantage. Finally, migration of ALCL cells was reduced by Shp2 shRNA. These findings show a direct involvement of Shp2 in NPM-ALK lymphomagenesis, highlighting its critical role in lymphoma cell proliferation and migration

Vascular endothelial growth factor-C stimulates the migration and proliferation of Kaposi's sarcoma cells.

Recent evidence suggesting vascular endothelial growth factor-C (VEGF-C), which is a regulator of lymphatic and vascular endothelial development, raised the question whether this molecule could be involved in Kaposi's sarcoma (KS), a strongly angiogenic and inflammatory tumor often associated with infection by human immunodeficiency virus-1. This disease is characterized by the presence of a core constituted of three main populations of "spindle" cells, having the features of lymphatic/vascular endothelial cells, macrophagic/dendritic cells, and of a mixed macrophage-endothelial phenotype. In this study we evaluated the biological response of KS cells to VEGF-C, using an immortal cell line derived from a KS lesion (KS IMM), which retains most features of the parental tumor and can induce KS-like sarcomas when injected subcutaneously in nude mice. We show that VEGFR-3, the specific receptor for VEGF-C, is expressed by KS IMM cells grown in vitro and in vivo. In vitro, VEGF-C induces the tyrosine phosphorylation of VEGFR-2, a receptor also for VEGF-A, as well as that of VEGFR-3. The activation of these two receptors in KS IMM cells is followed by a dose-responsive mitogenic and motogenic response. The stimulation of KS IMM cells with a mutant VEGF-C unable to bind and activate VEFGR-2 resulted in no proliferative response and in a weak motogenic stimulation, suggesting that VEGFR-2 is essential in transducing a proliferative signal and cooperates with VEGFR-3 in inducing cell migration. Our data add new insights on the pathogenesis of KS, suggesting that the involvement of endothelial growth factors may not only determine KS-associated angiogenesis, but also play a critical role in controlling KS cell growth and/or migration and invasion

Exhaled nitric oxide and nitric oxide synthase expression in Hodgkin's disease

Hodgkin's disease (HD) is a malignant lymphoma with frequent mediastinal involvement, characterized by a significant inflammatory infiltration. Exhaled Nitric Oxide (FENO), is present in healthy humans, and has been proven to be increased in eosinophilic diseases such as allergic asthma. We investigated whether FENO is increased in mediastinal HD and whether NO is produced by lymphoma tissue. To this aim FENO was measured in 56 HD patients, 17 with and 39 without bulky mediastinal involvement, in the period from January 2007 to December 2008. Thirty-seven patients were reassessed after remission. Lymph node biopsies of 10 patients were evaluated for inducible (iNOS) and constitutive (eNOS) nitric oxide synthase expression by immunohistochemistry. FENO resulted significantly related to the mediastinal mass maximum diameter (p=0.009) and was significantly higher in patients with as compared to those without bulky mediastinal disease (38.7 ppb, CI95% 19.3–58.0, versus 20.7 ppb, CI95% 16.6–24.7; p=0.009). iNOS and eNOS immunoreactivity was observed in tumour and inflammatory cells (eosinophils and histiocytes). Only in patients with bulky mediastinal HD there was a significant decrease in FENO (from 50.4 ppb CI95% 18.0–82.8 to 11.1 ppb CI95% 4.4–17.8, p=0.011). In conclusion, high FENO and NOS expression in lymph-nodes indicate that NO is a component of the inflammatory network of HD. FENO may be proposed for the assessment and follow up of bulky mediastinal HD patients

Follicular Origin of a Subset of CD5+ Diffuse Large B-Cell Lymphomas

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