Giorgio Palestro

Thymomas: A review of 169 cases, with particular reference to results of surgical treatment

One hundred sixty‐five patients with surgically treated thymoma were followed over 28 years; 73% had myasthenia gravis at presentation. Invasiveness was based on macroscopic findings at operation. Post‐surgical radiotherapy or chemotherapy were not routinely used. Overall survival was 84%, 79%, and 65% at 3, 5, and 10 years, respectively. Patients with invasive thymoma survived for a shorter period than patients with noninvasive tumors (67% versus 85% at 5 years); when radical excision was possible, no difference was detectable between the two groups. Patients with subtotally resected or only biopsied invasive thymomas survived 59% and 42% at 5 years, respectively. Lymphoepithelial cases had the worst prognosis of the histologic types considered. Myasthenia gravis did not adversely affect survival. Surgery is the basic treatment of thymomas. Macroscopic invasiveness and degree of excision judged by the surgeon have prognostic value and are reliable criteria of malignancy. Radiotherapy and chemotherapy may be effective, but their use should be limited to controlled trials. Cancer 58:765‐776, 1986.

Functional validation of the anaplastic lymphoma kinase signature identifies CEBPB and Bcl2A1 as critical target genes

Anaplastic large cell lymphomas (ALCLs) represent a subset of lymphomas in which the anaplastic lymphoma kinase (ALK) gene is frequently fused to the nucleophosmin (NPM) gene. We previously demonstrated that the constitutive phosphorylation of ALK chimeric proteins is sufficient to induce cellular transformation in vitro and in vivo and that ALK activity is strictly required for the survival of ALK-positive ALCL cells. To elucidate the signaling pathways required for ALK-mediated transformation and tumor maintenance, we analyzed the transcriptomes of multiple ALK-positive ALCL cell lines, abrogating their ALK-mediated signaling by inducible ALK RNA interference (RNAi) or with potent and cell-permeable ALK inhibitors. Transcripts derived from the gene expression profiling (GEP) analysis uncovered a reproducible signature, which included a novel group of ALK-regulated genes. Functional RNAi screening on a set of these ALK transcriptional targets revealed that the transcription factor C/EBPbeta and the antiapoptotic protein BCL2A1 are absolutely necessary to induce cell transformation and/or to sustain the growth and survival of ALK-positive ALCL cells. Thus, we proved that an experimentally controlled and functionally validated GEP analysis represents a powerful tool to identify novel pathogenetic networks and validate biologically suitable target genes for therapeutic interventions.

S-phase kinase-associated protein 2 expression in non-Hodgkin's lymphoma inversely correlates with p27 expression and defines cells in S phase.

The protein expression of the cyclin-dependent kinase inhibitor p27 is often deregulated in human tumors. In lymphomas the inactivation of p27 is achieved through either increased degradation(1) or sequestration via D cyclins,(2) and p27 protein levels have been shown to have a prognostic significance.(1,3) Recently, S-phase kinase-associated protein 2 (Skp2) has been proved to mediate p27 degradation in normal cells(4-7) and to have oncogenetic properties.(8,9) In this study, B-, T-, and myeloid hematopoietic cell lines and a well-characterized panel of human lymphomas (n = 244) were studied for the expression of Skp2. In human lymphomas, the expression of Skp2 strongly related to the grade of malignancy, being low in indolent tumors and very high in aggressive lymphomas. Moreover, the percentages of Skp2- and S-phase-positive cells, as measured by DNA content or BrdU labeling, strictly matched and closely parallel that of Ki-67 and cyclin A. An inverse correlation between Skp2 and p27 was found in the majority of lymphoma subtypes. Nonetheless, most mantle cell lymphomas and a subset of diffuse large cell lymphomas failed to show this correlation, suggesting that alternative pathway(s) for the regulation of p27 might exist. The detection of Skp2 protein either by flow cytometry or by immunohistochemistry represents a simple method to precisely assess the S phase of lymphomas. The potential diagnostic and prognostic value of Skp2 is discussed.

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.

Cooperative Induction of a Tolerogenic Dendritic Cell Phenotype by Cytokines Secreted by Pancreatic Carcinoma Cells

Ag presentation by dendritic cells (DC) is essential to effective antitumor T cell responses in cancer patients. Depending on their origin, maturation state, and the ambient cytokine milieu, DC can differentiate into distinct subpopulations, which preferentially either induce Th1 cell activation (CD11c+,CD123− myeloid DC (MDC)) or immunosuppressive T cell development (CD11c−,CD123+ plasmacytoid DC (PDC)). The present study was undertaken to characterize the effects of pancreatic carcinoma cell-derived cytokines on immature monocyte-derived DC (iMo-DC) in vitro and in vivo. Medium conditioned by human pancreatic carcinoma cells inhibited iMo-DC proliferation, expression of costimulatory molecules (CD80 and CD40) and of HLA-DR, and functional activity as assessed by MLR and IL-12p70 production. iMo-DC generated from pancreatic carcinoma patients in advanced stages of the disease similarly showed decreased levels of HLA-DR expression and reduced ability to stimulate MLR in response to CD40L and IFN-γ. Moreover, in tumor-patient peripheral blood, the ratio of MDC to PDC cells was lower than in healthy controls due to reduced numbers of MDC CD11c+ cells. Importantly, rather than a single cytokine, a combination of tumor-derived cytokines was responsible for these effects; these were primarily TGF-β, IL-10, and IL-6, but not vascular endothelial growth factor. In summary, we have identified an array of pancreatic carcinoma-derived cytokines that cooperatively affect iMo-DC activation in a manner consistent with ineffective antitumor immune responses.

Rearrangements of bcl-6, bcl-2, c-myc and 6q deletion in B-diffuse large-cell lymphoma: Clinical relevance in 71 patients

BACKGROUND B-diffuse large-cell lymphomas (DLCL) have been associated with some molecular lesions, but the role of such lesions as prognostic markers is still controversial. This report concerns an investigation of the frequency and clinical correlation of bcl-6, bcl-2, c-myc rearrangements and 6(q) deletions in B-DLCL. PATIENTS AND METHODS The presence of these genetic lesions was analyzed in samples of lymph nodes or bone marrow collected at diagnosis in 71 patients with B-DLCL, all treated with an anthracycline-containing chemotherapy regimen. RESULTS Rearrangement of bcl-6 was found in 11 patients (15%), rearranged bcl-2 in 12 (17%), 6(q) deletions in 10 patients (14%) and c-myc rearrangement in four (6%). Patients with rearranged bcl-6 tended to have a more aggressive disease than patients with germ-line bcl-6 (intermediate-high/high risk according to IPI criteria: 73% vs. 43%), but there were no differences in three-year survival rates (62% vs. 42%) between the two groups. The numbers of involved extranodal sites were similar in patients with rearranged and those with germ-line bcl-6. Patients with bcl-2 rearrangement appeared to have a less aggressive disease than those with germ-line bcl-2 (low/ low-intermediate risk 75% vs. 47%) and a slightly better three-year survival rate (70% vs. 41%) but again the difference was not significant. Both groups with or without 6(q) deletion had similar clinical characteristics and outcomes. The four patients with c-myc rearrangement had aggressive disease and did poorly. CONCLUSIONS The analysis of molecular lesions in B-DLCL may be useful for a better diagnostic definition; however, in this study we were unable to show that the evaluated genetic lesions had a significant impact on clinical outcome.

Immunohistological evidences of cortical and medullary differentiation in thymoma

The phenotypical characteristics of human epithelial and lymphoid cells have been studied with immunohistochemical methods on frozen sections of 12 thymomas. On the basis of the cytohistological characteristics of thymoma epithelial cells (EC) the thymomas were divided in cortical, medullary and mixed types, according to recently developed light microscopical criteria. When tested with a series of monoclonal antibodies, thymoma EC were all stained by the antibody Ki-M3 (as in the thymus), but reacted with anti-HLA-DR, anti-HLA-A,B,C and with a new monoclonal antibody to cortical EC,21A6, to a lesser extent and with weaker, variable intensity in comparison with the normal thymus. Cortical type thymomas were most reactive and the medullary type almost negative. Thymomas, like normal thymus showed different immunoreactivity patterns with antibodies to prekeratins of different specificities. Cortical type thymomas and areas in mixed thymoma showed an EC staining with the antibody to non-squamous type keratin (35βH11) whereas medullary type thymomas and areas showed staining with antibodies to squamous-type keratin (34βE12-IV/82) in addition. Lymphoidcellswithcortical(OKT6+,Leu 1 weakly+,Leu2a+,Leu3a+) or mature medullary (OKT6-, Leu 1 strongly+, Leu 2a or Leu 3a+) phenotype were found to colonize tumours with diferent EC types. These immunohistochemical findings largely confirm our earlier cytological distinction of thymoma EC. In addition important differences have been observed in neoplastic cortical EC concerning the HLA-DR and 21A6 immunoreactivity that may be intimately related to the neoplastic process and paraneoplastic immune phenomena.

Variable expression of leucocyte-common (CD45) antigen in CD30 (Ki1)-positive anaplastic large-cell lymphoma: Implications for the differential diagnosis between lymphoid and nonlymphoid malignancies

Monoclonal antibodies (mAbs) directed against the leucocyte common (CD45) antigen have been proposed as a useful tool for the differential diagnosis between malignant lymphomas (CD45+) and poorly differentiated nonhemopoietic tumors (CD45-). Thanks to the availability of mAbs directed against fixative-resistant epitopes of the CD45 molecule, this distinction can now easily be made even in routinely processed tissues. However, a small percentage of morphologically poorly defined neoplasms are difficult to diagnose even with the help of immunohistochemistry. The investigators report that 63 out of 165 anaplastic large-cell (ALC) lymphomas did not show any reactivity for the CD45 antigen in paraffin sections. In routine biopsies, the lymphomatous nature of these cases, most of which had been sent for consultation, could be always unequivocally established by demonstrating negativity for cytokeratins (mAb KL1) and clear dot-like and/or surface reactivity with the Ber-H2 mAb, which is directed against a fixative-resistant epitope of the lymphoid cell activation antigen CD30. Strikingly, 54% of the CD45-cases reacted with mAbs directed against fixative-resistant epitopes of the T cell-restricted CD45RO antigen (mAb UCHL1) or the B-restricted molecules CD45RA (mAb 4KB5) and L26 (unclustered). In order to avoid confusion of ALC lymphomas with anaplastic nonlymphoid tumors, pathologists must be aware of the existence of CD30+/CD45- ALC lymphomas, as they can mimic the above-mentioned malignancies both morphologically (due to the sinusoidal growth pattern) and phenotypically (due to the expression of EMA). The investigators conclude that the combined use of mAbs directed against fixative-resistant epitopes of the CD30, CD45RO, CD45RA, and L26 antigens and cytokeratins is essential for the correct diagnosis and treatment of these equivocal cases.

Prolactin in autoimmunity and antitumor defence

Prolactin (PRL) enhances inflammatory and antitumor responses in vitro and thus exhibits Th1-type cytokine-like effects. Evidence from experimental models indicates that inhibition of PRL release by bromocriptine downregulates immune reactions and ameliorates autoimmune diseases in which Th1 responses are predominant. A direct effect of locally produced PRL in some Th1 diseases, such as rheumatoid arthritis, supports this concept. Paradoxically, however, hyperprolactinemia can also be associated with conditions such as pregnancy, where remission of Th1-mediated diseases is known to occur in the context of a Th2-dominated milieu. This reversal of the Th1-promoting effect of PRL may be due to major changes in the levels of other hormones that can annul and/or override the PRL-mediated proinflammatory state. Nevertheless, PRL, as an immunopotentiating agent, may have a powerful therapeutic role in cancer and other immunocompromised patients.

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.