Anaplastic lymphoma kinase (ALK) is not expressed in Hodgkin's disease: results with ALK-11 antibody in 327 untreated patients

Hodgkin Lymphoma with Unusual Intrasinusoidal Pattern of Infiltration

In spite of recent great advances in our understanding of both Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL), occasionally there are CD30-positive large cell hematopoietic neoplasms, in which the morphologic and phenotypic features overlap to such an extent that they cannot easily be classified. We report a histologically unusual case of HL that mimicked ALCL, but had phenotypical characteristics of HL. The neoplastic cells resembling Reed-Sternberg cells or Hodgkin cells were mainly situated within sinusoidal spaces, which are characteristically seen in ALCL. However, they showed unequivocal expression of both CD30 and CD15, and no aberrant antigen expression to suggest ALCL (BSAP+, EMA-, LCA-, CD43-, CD2-, CD3-, CD4-, CD45RO-, ALK-, granzymeB-), with negative TCR gene rearrangement and no expression of EBV. HL with intrasinusoidal pattern has rarely been described, but we suggest that, although cases of HL with such a striking sinusoidal pattern are rare, nevertheless do exist. Since the identification of sinusoidal infiltration by CD30-positive neoplastic cells may lead to a mistaken view of ALCL, wide panel of antibodies should be used to confirm the diagnosis.

CD26, together with cell surface adenosine deaminase, is selectively expressed on ALK-positive, but not on ALK-negative, anaplastic large cell lymphoma and Hodgkin's lymphoma

CD26/dipeptidyl peptidase IV is a cell surface antigen with multiple biological functions. Although its involvement in tumor biology has been suggested, the significance of its expression in malignant lymphoma has not been clarified in detail. This study examined the expression of CD26 and cell surface adenosine deaminase (ADA) in 42 cases of Hodgkin's lymphoma (HL) and T-cell lymphoma by immunohistochemistry on frozen sections. CD26 was expressed in three of 14 cases of HL, in four of eight cases of anaplastic large cell lymphoma (ALCL), in two of nine cases of peripheral T-cell lymphoma, in one of six cases of lymphoblastic lymphoma and in none of three cases of adult T-cell lymphoma/leukemia. Expression of cell surface ADA was fully correlated with the expression of CD26 and expression of CD26/ADA in ALCL and HL was also completely correlated with the expression of p80 and epithelial membrane antigen. Of 10 CD26-positive patients, seven had fever and elevated CRP at initial diagnosis and over a median follow-up of 61 months (range, 7 - 152 months) only three survived. This study suggested that CD26 is selectively expressed on ALK-positive, but not on ALK-negative, ALCL and HL. This is also the first report to demonstrate that ADA is coexpressed with CD26 on the cell surface of malignant neoplasms in vivo.

Intrinsic apoptotic pathway in anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) includes a subset of tumors that has abnormalities of chromosome 2p23, resulting in overexpression of anaplastic lymphoma kinase (ALK). Previous studies have reported differences in apoptotic rate and expression levels of apoptosis regulatory proteins between ALK+ and ALK- ALCL. In this study, we assessed for expression of the intrinsic apoptotic pathway proteins cytochrome c, apoptosis protease-activating factor 1, and procaspase 9 in 2 ALK+ ALCL cell lines and 42 ALCL tumors (17 ALK+, 25 ALK-). We used the Karpas 299 and SU-DHL-1 cell lines, and the inhibitors Z-LEHD-FMK (specific for caspase 9) and Boc-D-FMK (general caspase inhibitor) to investigate the role of caspase 9 activation in chemotherapy-induced apoptotic cell death. Caspase 9 activity was significantly increased in Karpas-299 and SU-DHL-1 cells after chemotherapy treatment, but remained as low as control levels with addition of either caspase inhibitor. Both caspase inhibitors rescued a substantial fraction of Karpas 299 and SU-DHL-1 cells from drug-induced cell death. In ALCL tumors, expression of cytochrome c, apoptosis protease-activating factor 1, and procaspase 9 was also assessed and correlated with apoptotic rate and activated caspase 3 levels. Cytochrome c was expressed in all 13 (100%) ALK+ and 18 (95%) of 19 ALK- ALCL tumors. Apoptosis protease-activating factor 1 was detected in 14 (88%) of 16 ALK+ and 19 (79%) of 24 ALK- ALCL tumors. Procaspase 9 was expressed in 5 (30%) of 17 ALK+ and 2 (8%) of 25 ALK- ALCL tumors (P = .09). In the entire study group (ALK+ and ALK- ALCL), procaspase 9 expression levels significantly correlated with apoptotic rate (P = .02) and activated caspase 3 levels (P = .05). This correlation could not be shown in the ALK+ or ALK- ALCL subgroups, presumably because of the small sample size. In conclusion, chemotherapy-induced cell death in ALK+ ALCL cells involves the intrinsic apoptotic pathway, and apoptosome function may be an important determinant of apoptosis in ALCL tumors.

Suppressor of cytokine signaling 3 expression in anaplastic large cell lymphoma

Using a cDNA microarray, we found that suppressor of cytokine signaling 3 (SOCS3) is highly expressed in anaplastic lymphoma kinase (ALK)+ anaplastic large cell lymphoma (ALCL) cell lines. As SOCS3 is induced by activated signal transducer and activator of transcription 3 (STAT3), and ALK activates STAT3, we hypothesized that SOCS3 may play a role in ALK+ ALCL pathogenesis via the Janus kinase 3 (JAK3)-STAT3 pathway. Using ALCL cell lines, we show by coimmunoprecipitation experiments that SOCS3 physically binds with JAK3 in vitro, and that JAK3 inhibition by WHI-P154 downregulates SOCS3 expression. Western blot analysis confirmed expression of SOCS3 and also showed coexpression of phosphorylated (activated) STAT3 (pSTAT3). Direct sequencing of the SOCS3 gene showed no mutations or alternative splicing. In ALCL tumors that were assessed by immunohistochemistry, nine of 12 (75%) ALK+ tumors were SOCS3 positive and eight (67%) coexpressed pSTAT3. In comparison, 18 of 25 (72%) ALK-- tumors were SOCS3 positive and seven (28%) coexpressed pSTAT3. These results show that SOCS3 is overexpressed in ALCL, attributable to JAK3-STAT3 activation and likely related to ALK in ALK+ tumors. However, SOCS3 is also expressed in tumors that lack STAT3 and ALK suggesting alternative mechanisms of upregulation.

Molecular biology of anaplastic lymphoma kinase-positive anaplastic large-cell lymphoma

Anaplastic large-cell lymphoma (ALCL) provides an excellent example of how molecular insights into tumor pathogenesis are influencing and improving tumor classification. ALCL was described initially as a subtype of T-cell/null-cell lymphoma characterized by unusual tumor cell morphology and the expression of CD30. However, it was soon recognized that a subset of ALCLs contained chromosomal translocations involving anaplastic lymphoma kinase (ALK), a novel receptor tyrosine kinase gene. These rearrangements create chimeric genes encoding self-associating, constitutively active ALK fusion proteins that activate a number of downstream effectors, including phospholipase C-gamma, phosphoinositol 3'-kinase, RAS, and signal transducer and activator of transcription proteins, all of which seem potentially important in cellular transformation. Not all tumors classified as ALCLs have ALK rearrangements and, conversely, ALK rearrangements occur in lymphomas of widely varying morphology. Hence, only molecular markers can reliably identify ALK+ ALCL. The importance of doing so is reflected by clinical studies suggesting that ALK+ ALCLs have a significantly better prognosis than other aggressive peripheral T-cell or B-cell lymphomas, including ALK- ALCLs. The unique molecular pathogenesis of ALK+ ALCL is likely to lead to novel therapeutic approaches directed at specific inhibition of ALK or downstream effectors.