Expression of the ALK protein by anaplastic large-cell lymphomas correlates with high proliferative activity

Clinical Significance of ALK-1 Gene Abnormalities in Diffuse Large Cell Lymphoma

Objectives

To detect relative frequency of anaplastic lymphoma kinase (ALK-1) gene abnormality in diffuse large cell lymphoma (DLCL) using fluorescence in situ hybridization (FISH), and correlate its presence with clinicopathological features which may be useful for choice of therapy and predict survival in newly diagnosed cases.

Patients and methods

A prospective study was done between March 2004 and October 2009. Fifty patients newly diagnosed with DLCL were enrolled into the study. Immunophenotyping was done and detection of ALK-1 gene abnormalities were carried out by immunohistochemically (IHC) and FISH. Patients that proved to be ALK-1 positive were treated with standard cyclophosphamide –hydroxy-daunorubicin- oncovin-prednisone (CHOP) protocol.

Results

All ALK +ve patients achieved complete remission (CR) vs. 93.5% CR and 6.5% partial remission (PR) for ALK −ve patients respectively. Disease free survival (DFS) at 24 months was 81.8% in the CHOP-14 group (ALK-1⁻) vs. 100% for the CHOP-21 group (ALK-1⁺). Overall survival (OS) at 30 months was 80.4% in the CHOP-14 group vs. 100% for the CHOP-21 group.

A case of T/null anaplastic large cell lymphoma arising in lung

Anaplastic large cell lymphoma (ALCL) is a rare non-Hodgkin, T-cell lymphoma, representing only 2-3% of all lymphoid neoplasm's in adults according to World Health Organization (WHO). CD30 antigen-positive, large neoplastic cells characterize ALCL. We present here a 46-year-old male with pulmonary ALCL previously diagnosed with Hodgkin disease. Microscopically, atypical bi-and multinucleated cells with frequent mitoses were present. The neoplastic cells were large and had clear cytoplasm, large vesicular nuclei, and prominent nucleoli. Immunophenotypic analysis revealed LCA, vimentin and CD30 positivity. ALK immunostaining was negative. Immunohistochemical profile was consistent with ALK negative ALCL. The progression of Hodgkin lymphoma to aggressive non-Hodgkin lymphoma (ALCL in this case) is well known entity. After the diagnosis was established, our patient immediately had been referred to the Department of Hematology in order to get appropriate chemotherapy, necessary in such cases.

Ubiquitination and proteasomal degradation of nucleophosmin-anaplastic lymphoma kinase induced by 17-allylamino-demethoxygeldanamycin: role of the co-chaperone carboxyl heat shock protein 70-interacting protein

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is a constitutively active fusion tyrosine kinase involved in lymphomagenesis of human anaplastic large cell lymphomas (ALCL), the maturation and activity of which depend on the association with the heat shock protein (hsp) 90 protein chaperone. Targeting hsp90 by the ansamycins geldanamycin and 17-allyl-amino-demethoxygeldanamycin (17-AAG) promotes degradation of several proteins through the ubiquitin-proteasome pathway, including oncogenic Raf, v-Src, erbB2, and BCR-ABL. We have previously shown that 17-AAG prevents hsp90/NPM-ALK complex formation and fosters NPM-ALK turnover, perhaps through its association with the hsp70 chaperone. Here, we show that inhibition of the proteasome activity by the potent and specific compound pyrazylcarbonyl-Phe-Leu-boronate (PS-341) blocks 17-AAG-induced down-regulation of NPM-ALK, which becomes detergent-insoluble and relocates into ubiquitin-rich perinuclear vesicles that represent aggregated polyubiquitinated forms of the protein. Kinase activity was not mandatory for proteasomal degradation of NPM-ALK, because kinase-defective NPM-ALK was even more rapidly degraded upon 17-AAG treatment. Prolonged exposure to the proteasome inhibitor was shown to trigger caspase-3-mediated apoptosis in proliferating ALCL cells at nanomolar concentrations. However, we verified that the accumulation of detergent-insoluble NPM-ALK in ALCL cells was not a spurious consequence of PS341-committed apoptosis, because caspase inhibitors prevented poly(ADP-ribose) polymerase cleavage whereas they did not affect partitioning of aggregated NPM-ALK. In line with these observations, the carboxyl hsp70-interacting ubiquitin ligase (CHIP), was shown to increase basal ubiquitination and turnover of NPM-ALK kinase, supporting a mechanism whereby NPM-ALK proceeds rapidly toward hsp70-assisted ubiquitin-dependent proteasomal degradation, when chaperoning activity of hsp90 is prohibited by 17-AAG.

Anaplastic lymphoma kinase proteins in growth control and cancer

The normal functions of full-length anaplastic lymphoma kinase (ALK) remain to be completely elucidated. Although considered to be important in neural development, recent studies in Drosophila also highlight a role for ALK in gut muscle differentiation. Indeed, the Drosophila model offers a future arena for the study of ALK, its ligands and signalling cascades. The discovery of activated fusion forms of the ALK tyrosine kinase in anaplastic large cell lymphoma (ALCL) has dramatically improved our understanding of the pathogenesis of these lymphomas and enhanced the pathological diagnosis of this subtype of non-Hodgkin's lymphoma (NHL). Likewise, the realisation that a high percentage of inflammatory myofibroblastic tumours express activated-ALK fusion proteins has clarified the causation of these mesenchymal neoplasms and provided for their easier discrimination from other mesenchymal-derived inflammatory myofibroblastic tumour (IMT) mimics. Recent reports of ALK expression in a range of carcinoma-derived cell lines together with its apparent role as a receptor for PTN and MK, both of which have been implicated in tumourigenesis, raise the possibility that ALK-mediated signalling could play a role in the development and/or progression of a number of common solid tumours. The therapeutic targeting of ALK may prove to have efficacy in the treatment of many of these neoplasms.

Cell kinetics and cell cycle regulation in lymphomas

The proliferative indices of non-Hodgkin's lymphomas are useful prognostic indicators and provide information independent of other histological and clinical variables. However, proliferative indices alone do not suffice to characterise cell growth. A high cell production rate may be compensated, almost or fully, by a high cell deletion rate. A re-evaluation of parameters of cell kinetics in view of our increasing knowledge of the molecular pathways of cell cycle control may provide more prognostic information for the management of patients with malignant lymphomas.

Proteins encoded by genes involved in chromosomal alterations in lymphoma and leukemia: clinical value of their detection by immunocytochemistry

Acquired chromosomal anomalies (most commonly translocations) in lymphoma and leukemia usually result in either activation of a quiescent gene (by means of immunoglobulin or T-cell-receptor promotors) and expression of an intact protein product, or creation of a fusion gene encoding a chimeric protein. This review summarizes current immunocytochemical studies of these 2 categories of oncogenic protein, with emphasis on the clinical relevance of their detection in diagnostic samples. Among the quiescent genes activated by rearrangement, expression of cyclin D1 (due to rearrangement of the CCND1 [BCL-1] gene) is a near-specific marker of t(11;14) in mantle cell lymphoma; BCL-2 expression distinguishes follicular lymphoma cells from their nonneoplastic counterparts in reactive germinal centers and appears to be an independent prognostic marker in diffuse large cell lymphoma; and TAL-1 (SCL) expression identifies T-cell acute lymphoblastic neoplasms in which this gene is activated. The protein products of other genes activated by chromosomal rearrangement have a role as markers of either lineage (eg, PAX-5 [B-cell-specific activator protein] for B cells, including B-lymphoblastic neoplasms), or maturation stage (eg, BCL-6 for germinal-center and activated B cells and MUM-1/IRF4 for plasma cells). Currently, no hybrid protein encoded by fusion genes is reliably detectable by antibodies recognizing unique junctional epitopes (ie, epitopes absent from the wild-type constituent proteins). Nevertheless, staining for promyelocytic leukemia (PML) protein will detect acute PML with t(15;17) because the microspeckled nuclear labeling pattern for PML-RARalpha is highly distinctive. Similarly, antibodies to the anaplastic lymphoma kinase (ALK) tyrosine kinase are valuable (because wild-type ALK is not found in normal lymphoid tissue) in detecting neoplasms (CD30-positive large T-cell lymphomas) with t(2;5) or its variants. Thus, immunocytochemical detection of the products of many rearranged genes in lymphoma and leukemia can be clinically informative and provide information on cellular and subcellular protein expression that cannot be inferred from studies based on messenger RNA.

Anaplastic lymphoma kinase proteins and malignancy

The anaplastic lymphoma kinase (ALK) gene fuses to the nucleophosmin (NPM) gene as a result of a (2;5) translocation associated with a subtype of human lymphoma (initially designated anaplastic large cell lymphoma [ALCL] or Ki-1/CD30-positive lymphoma). The immunocytochemical detection of NPM-ALK (and proteins encoded by other ALK fusion genes) has allowed the definition of a tumor entity, "ALK-positive lymphoma" (which shows only partial overlap with pathologists' diagnosis of ALCL), to be defined and is invaluable in distinguishing this disease from ALK-negative large cell lymphomas. Eight variant ALK fusion proteins have been identified. Some are expressed only in ALCL, some are found only in the nonhematopoietic neoplasm inflammatory myofibroblastic tumor (IMT), and some are present in both types of malignancy. The ALK gene is silent in adult tissues except for restricted sites within the nervous system (consequently, patients with ALK-positive lymphoma produce antibodies to the ALK protein) but is expressed in some neuroblastomas and rhabdomyosarcomas. Biochemical studies suggest an anti-apoptotic function of NPM-ALK, and this may contribute to oncogenesis. Although ALK-positive lymphomas have a generally good prognosis, new therapeutic regimens are still needed for patients whose disease is refractory to conventional treatment.