NPM/ALK gene fusion transcripts identify a distinct subgroup of null type Ki-1 positive anaplastic large cell lymphomas

The chromosomal aberration t(2:5) resulting in the juxtaposition of NPM and ALK genes is a well-known feature of several Ki-1+ anaplastic large cell lymphomas (ALCL) of the T-cell type. However, conflicting results have been reported concerning the presence of this gene rearrangement in other ALCL and Hodgkin's disease (HD), respectively. We performed NPM/ALK RT-PCR on 14 cases of ALCL expressing distinct myelomonocytic markers, e.g. CD11c, CD13, CD14 or CD68, but neither T-cell nor B-cell associated antigens (null cell phenotype). The specific translocation was found exclusively in six childhood tumours previously diagnosed as malignant histiocytosis (MH), whereas all adult lymphomas (three ALCL without characteristics of MH, three secondary ALCL following HD) and two paediatric cases of secondary ALCL following HD did not show NPM/ALK gene fusion products. By Southern blotting, the status of T-cell receptor (TCR) and immunoglobulin heavy chain genes (IgH) were investigated; two patients with initially diagnosed MH had the TCRdelta-chain gene rearranged (Ddelta2-Ddelta3 and Vdelta1-Jdelta1, respectively). IgH rearrangements were detected in only one patient with secondary ALCL. Our data indicate a high association of previously diagnosed MH and NPM/ALK gene rearrangements. In one case, this specific translocation was demonstrated at an early stage of development; in another, a mature TCRdelta-chain gene rearrangement was detected. These data support the hypothesis of a lymphoid origin of this subgroup of Ki-1 positive ALCL previously diagnosed as MH.     

Detection of normal and chimeric nucleophosmin in human cells

In anaplastic large-cell lymphoma (ALCL), the (2;5) chromosomal translocation creates a fusion gene encoding the 80-kD NPM-ALK hybrid protein. This report describes three new monoclonal antibodies, two of which recognize, by Western blotting, the N-terminal portion of NPM present in the NPM-ALK fusion protein and also in two other NPM fusion proteins (NPM-RARalpha and NPM-MLF1). The third antibody recognizes the C-terminal portion (deleted in NPM-ALK) and reacts only with wild-type NPM. The three antibodies immunostain wild-type NPM (in paraffin-embedded normal tissue samples) in cell nuclei and in the cytoplasm of mitotic cells. Cerebral neurones, exceptionally, show diffuse cytoplasmic labeling. In contrast to normal tissues, the two antibodies against the N-terminal portion of NPM labeled the cytoplasm of neoplastic cells, in four ALK-positive ALCL, reflecting their reactivity with NPM-ALK fusion protein, whereas the antibody to the C-terminal NPM epitope labeled only cell nuclei. Immunocytochemical labeling with these antibodies can therefore confirm that an ALK-positive lymphoma expresses NPM-ALK (rather than a variant ALK-fusion protein) and may also provide evidence for chromosomal anomalies involving the NPM gene other than the classical (2;5) translocation.     

The cryptic inv(2)(p23q35) defines a new molecular genetic subtype of ALK-positive anaplastic large-cell lymphoma

Recently, a distinctive entity characterized by expression of the anaplastic lymphoma kinase (ALK) protein [most frequently due to the t(2;5)(p23;q35)-associated NPM-ALK fusion] has emerged within the heterogenous group of non-Hodgkin's lymphomas (NHL) classified as anaplastic large-cell lymphoma (ALCL). Sporadic variant 2p23/ALK abnormalities identified in ALK-positive ALCL indicate that genes other than NPM may also be involved in the deregulation of ALK and lymphomagenesis. We report here three cases with an inv(2)(p23q35) detected by fluorescence in situ hybridization (FISH) in young male patients with ALK-positive ALCL. In contrast to ALCL cases with the classical t(2;5)(p23;q35) that usually show both cytoplasmic and nuclear or predominantly nuclear alone localization of the NPM-ALK chimeric product, in all three cases with an inv(2)(p23q35) the ALK protein accumulated in the cytoplasm only, supporting the previous assumption that the oncogenic potential of ALK may not be dependent on its nuclear localization. As the first step to identify the ALK partner gene involved in the inv(2)(p23q35), we performed extensive FISH studies and demonstrated that the 2q35 breakpoint occurred within the 1,750-kb region contained within the 914E7 YAC. Moreover, a striking association of the inv(2)(p23q35) with a secondary chromosomal change, viz, ider(2)(q10)inv(2)(p23q35), carrying two additional copies of the putative ALK-related fusion gene, was found in all three patients, suggesting that, in contrast to the standard t(2;5)/NPM-ALK fusion, multiple copies of the putative 2q35-ALK chimeric gene may be required for efficient tumor development. In summary, we demonstrate that the inv(2)(p23q35), a variant of the t(2;5)(p23;q35), is a recurrent chromosomal abnormality in ALK-positive ALCL, the further characterization of which should provide new insight into the pathogenesis of these lymphomas.     

Detection of the t(2;5)-associated NPM/ALK fusion cDNA in peripheral blood cells of healthy individuals

The translocation t(2;5), which leads to the fusion of the nucleophosmin gene (NPM) on chromosome 5q35 to the receptor kinase ALK on chromosome 2p23, is found in CD30+ anaplastic large cell lymphomas and some cases of B-cell lymphoma. Hodgkin's disease (HD) is a malignant lymphoma characterized by large multinucleated tumour cells, Hodgkin and Reed-Sternberg (H&RS) cells, surrounded by a dense lymphohistiocytic infiltrate. Our group recently demonstrated NPM/ALK fusion cDNAs by single-cell RT-PCR in < 3% of CD30+ tumour cells in 2/9 cases of HD. To further delineate the relevance of this finding for HD, we studied the occurrence of NPM/ALK fusion genes in peripheral blood cells of healthy donors by RT-PCR. NPM/ALK fusion cDNAs were found by RT-PCR in 14/29 healthy individuals and confirmed by hybridization with a breakpoint-specific oligonucleotide. Due to the low rate of NPM/ALK-positive cells in the peripheral blood of positive individuals, an assignment to a defined cellular subpopulation was not possible. We conclude that NPM/ALK fusion genes are present in peripheral blood cells of healthy donors. After t(14;18) and t(9;22), t(2;5) represents the third example of tumour-associated translocation products in blood cells of apparently healthy donors. The implications of this finding are discussed.     

原发系统性间变性大细胞淋巴瘤临床病理特征及免疫表型分析

目的 分析原发系统性间变性大细胞淋巴瘤( ALCL)的临床病理特征和免疫组织化学特点,提高诊治水平。方法选取22例ALCL患者,均进行分期、国际预后指数(IPI)、乳酸脱氢酶(LDH)检测,应用免疫组织化学SP法检测间变性淋巴瘤激酶(ALK)、Ki-67、Caspase-3、CD30、EMA、Granzyme B等,回顾性分析患者临床、病理形态学资料、免疫表型及生物学特性,并进行预后分析。结果22例均为原发系统性ALCL,ALK+ 15例(68.2％),ALK-7例(31.8％);AILK+患者发病年龄、Ki-67增殖指数较ALK-患者低,Caspase-3表达率高,差异有统计学意义(x2 =4.618,P= 0.032);15例ALK+ALCL均表达CD30和EMA。ALCL中ALK的表达与Ki-67、Caspase-3的表达呈负相关(r= -0.581,P= 0.006;r=0.458,P=0.032)。ALK+病例较ALK-病例GranzymeB(x2=0.11,P=0.74)、TIA-1( x2= 0.01,P=0.92)的表达率高,但差异无统计学意义(P＞0.05)。有效率为54.5％(12/22),其中完全缓解率为18.2％(4/22);全组中位生存期12个月,1年生存率为59.1％( 13/22),2年生存率为50.0％(11/22)。Ann Arbor分期、LDH及IPI与疾病预后相关。结论ALK+较ALK-ALCL患者核增殖低,恶性程度低,临床特征和免疫表型具有一定的特征性;ALK、Ki-67、Caspase-3、分期、血清LDH及IPI对预测ALCL患者的生存和指导治疗有帮助。     

Frequent expression of the NPM-ALK chimeric fusion protein in anaplastic large-cell lymphoma, lympho-histiocytic type

The revised European-American lymphoma classification recognizes a subtype of anaplastic large-cell lymphoma (ALCL), termed lympho-histiocytic because of its peculiar cytological composition. As in the case of classical ALCL, this tumor usually occurs in young patients and shows an excellent response to chemotherapy, but some authors have suggested that in reality this is a nonanaplastic T-cell lymphoma rich in histiocytes. In this paper, we show that three of five cases of lympho-histiocytic ALCL stain with anti-ALK antibodies and can therefore be presumed to express the chimeric NPM/ALK protein secondary to (2;5) translocation. These findings further support the inclusion of this as a type of ALCL and not among the nonanaplastic peripheral T-cell lymphomas. Furthermore, they indicate that staining for ALK proteins is a powerful tool for the diagnosis of lympho-histiocytic ALCL, the recognition of which may be difficult on morphological grounds.     

Panhandle PCR: a technical advance to amplify MLL genomic translocation breakpoints

Translocations involving a breakpoint cluster region of the MLL gene at chromosome band 11q23 are the most common molecular abnormalities in acute leukemias of infants and acute leukemias related to chemotherapy with DNA topoisomerase II inhibitors. Molecular cloning of MLL genomic breakpoints by PCR has previously been difficult because MLL has many translocation partners and several breakpoints involve unknown partner genes. We review a new approach to MLL genomic breakpoint cloning called panhandle PCR. By adding an oligonucleotide sequence to the unknown 3' partner gene that is complementary to a known 5' MLL sequence, we have been able to generate a genomic template with an intrastrand loop for PCR schematically shaped like a pan with a handle. The intrastrand loop contains the translocation breakpoint and unknown partner DNA, while the handle contains the known 5' sequence from MLL and a complement to that sequence. Primers both derived from MLL are used to amplify the breakpoint by panhandle PCR. Panhandle PCR offers the advantage of having specificity for the strand of interest at both primer annealing sites without requiring specific primers for the many partner genes of MLL. Panhandle PCR is a straightforward method that represents a technical advance in MLL genomic breakpoint cloning.     

CD30(+) anaplastic large-cell lymphoma in children: analysis of 82 patients enrolled in two consecutive studies of the French Society of Pediatric Oncology

The purpose of this study was (1) to investigate the efficacy of chemotherapy regimens designed by the French Society of Pediatric Oncology for childhood anaplastic large-cell lymphoma (ALCL) and (2) to identify prognostic factors in these children. Eighty-two children with newly diagnosed ALCL were enrolled in two consecutive studies, HM89 and HM91. The diagnosis of ALCL was based on immuno-morphological features and all the cases but 2 were investigated using ALK1 antibody directed to the NPM/ALK protein associated with the 2;5 translocation. Treatment consisted of 2 courses of COPADM (methotrexate, cyclophosphamide, doxorubicin, vincristine, and prednisone) and a maintenance treatment of 5 to 7 months. Seventy-eight patients (95%) achieved a complete remission and 21 relapsed. The probability of survival and event-free survival at 3 years was of 83% (72% to 90%) and 66% (54% to 76%), respectively, with a median follow-up of 49 months. In multivariate analysis, visceral involvement, mediastinal involvement, and lacticodeshydrogenase (LDH) level >/=800 UI/L were shown to be predictive of a higher risk of failure. In conclusion, this type of regimen demonstrated efficacy in childhood ALCL. However, therapeutic results have to be improved for children with adverse prognostic parameters such as visceral or mediastinal involvement or a high LDH level.     

ALK expression defines a distinct group of T/null lymphomas ("ALK lymphomas") with a wide morphological spectrum

The t(2;5)(p23;q35) translocation associated with CD30-positive anaplastic large cell lymphoma results in the production of a NPM-ALK chimeric protein, consisting of the N-terminal portion of the NPM protein joined to the entire cytoplasmic domain of the neural receptor tyrosine kinase ALK. The ALK gene products were identified in paraffm sections by using a new anti-ALK (cytoplasmic portion) monoclonal antibody (ALKc) that tends to react more strongly than a previously described ALK1 antibody with the nuclei of ALK-expressing tumor cells after microwave heating in 1 mmol/L ethylenediaminetetraacetic acid buffer, pH 8.0. The ALKc monoclonal antibody reacted selectively with 60% of anaplastic large cell lymphoma cases (60 of 100), which occurred mainly in the first three decades of life and consistently displayed a T/null phenotype. This group of ALK-positive tumors showed a wide morphological spectrum including cases with features of anaplastic large cell lymphoma "common" type (75%), "lymphohistiocytic" (10%), "small cell" (8.3%), "giant cell" (3.3%), and "Hodgkin's like" (3.3%). CD30-positive large anaplastic cells expressing the ALK protein both in the cytoplasm and nucleus represented the dominant tumor population in the common, Hodgkin's-like and giant cell types, but they were present at a smaller percentage (often with a perivascular distribution) also in cases with lymphohistiocytic and small cell features. In this study, the ALKc antibody also allowed us to identify small neoplastic cells (usually CD30 negative) with nucleus-restricted ALK positivity that were, by definition, more evident in the small cell variant but were also found in cases with lymphohistiocytic, common, and "Hodgkin's-like" features. These findings, which have not been previously emphasized, strongly suggest that the neoplastic lesion (the NPM-ALK gene) must be present both in the large anaplastic and small tumor cells, and that ALK-positive lymphomas lie on a spectrum, their position being defined by the ratio of small to large neoplastic cells. Notably, about 15% of all ALK-positive lymphomas (usually of the common or giant cell variant) showed a cytoplasm-restricted ALK positivity, which suggests that the ALK gene may have fused with a partner(s) other than NPM. From a diagnostic point of view, detection of the ALK protein was useful in distinguishing anaplastic large cell lymphoma cases of lymphohistiocytic and small cell variants from reactive conditions and other peripheral T-cell lymphoma subtypes, as well as for detecting a small number of tumor cells in lymphohemopoietic tissues. In conclusion, ALK positivity appears to define a clinicopathological entity with a T/null phenotype ("ALK lymphomas"), but one that shows a wider spectrum of morphological patterns than has been appreciated in the past.