High expression of Mcl-1 in ALK positive and negative anaplastic large cell lymphoma

A Combination of Alectinib and DNA-Demethylating Agents Synergistically Inhibits Anaplastic-Lymphoma-Kinase-Positive Anaplastic Large-Cell Lymphoma Cell Proliferation

The recent evolution of molecular targeted therapy has improved clinical outcomes in several human malignancies. The translocation of anaplastic lymphoma kinase (ALK) was originally identified in anaplastic large-cell lymphoma (ALCL) and subsequently in non-small cell lung carcinoma (NSCLC). Since ALK fusion gene products act as a driver of carcinogenesis in both ALCL and NSCLC, several ALK tyrosine kinase inhibitors (TKIs) have been developed. Crizotinib and alectinib are first- and second-generation ALK TKIs, respectively, approved for the treatment of ALK-positive ALCL (ALK+ ALCL) and ALK+ NSCLC. Although most ALK+ NSCLC patients respond to crizotinib and alectinib, they generally relapse after several years of treatment. We previously found that DNA-demethylating agents enhanced the efficacy of ABL TKIs in chronic myeloid leukemia cells. Moreover, aberrant DNA methylation has also been observed in ALCL cells. Thus, to improve the clinical outcomes of ALK+ ALCL therapy, we investigated the synergistic efficacy of the combination of alectinib and the DNA-demethylating agent azacytidine, decitabine, or OR-2100 (an orally bioavailable decitabine derivative). As expected, the combination of alectinib and DNA-demethylating agents synergistically suppressed ALK+ ALCL cell proliferation, concomitant with DNA hypomethylation and a reduction in STAT3 (a downstream target of ALK fusion proteins) phosphorylation. The combination of alectinib and OR-2100 markedly altered gene expression in ALCL cells, including that of genes implicated in apoptotic signaling, which possibly contributed to the synergistic anti-ALCL effects of this drug combination. Therefore, alectinib and OR-2100 combination therapy has the potential to improve the outcomes of patients with ALK+ ALCL.

Inhibition of MCL1 induces apoptosis in anaplastic large cell lymphoma and in primary effusion lymphoma

Overexpression of antiapoptotic BCL2 family proteins occurs in various hematologic malignancies and contributes to tumorigenesis by inhibiting the apoptotic machinery of the cells. Antagonizing BH3 mimetics provide an option for medication, with venetoclax as the first drug applied for chronic lymphocytic leukemia and for acute myeloid leukemia. To find additional hematologic entities with ectopic expression of BCL2 family members, we performed expression screening of cell lines applying the LL-100 panel. Anaplastic large cell lymphoma (ALCL) and primary effusion lymphoma (PEL), 2/22 entities covered by this panel, stood out by high expression of MCL1 and low expression of BCL2. The MCL1 inhibitor AZD-5991 induced apoptosis in cell lines from both malignancies, suggesting that this BH3 mimetic might be efficient as drug for these diseases. The ALCL cell lines also expressed BCLXL and BCL2A1, both contributing to survival of the cells. The combination of specific BH3 mimetics yielded synergistic effects, pointing to a novel strategy for the treatment of ALCL. The PI3K/mTOR inhibitor BEZ-235 could also efficiently be applied in combination with AZD-5991, offering an alternative to avoid thrombocytopenia which is associated with the use of BCLXL inhibitors.

The Dual Role of Autophagy in Crizotinib-Treated ALK+ ALCL: From the Lymphoma Cells Drug Resistance to Their Demise

Autophagy has been described as harboring a dual role in cancer development and therapy. Depending on the context, it can exert either pro-survival or pro-death functions. Here, we review what is known about autophagy in crizotinib-treated ALK⁺ ALCL. We first present our main findings on the role and regulation of autophagy in these cells. Then, we provide literature-driven hypotheses that could explain mechanistically the pro-survival properties of autophagy in crizotinib-treated bulk and stem-like ALK⁺ ALCL cells. Finally, we discuss how the potentiation of autophagy, which occurs with combined therapies (ALK and BCL2 or ALK and RAF1 co-inhibition), could convert it from a survival mechanism to a pro-death process.

Methotrexate significantly induces apoptosis by inhibiting STAT3 activation in NPM-ALK-positive ALCL cells

Anaplastic large cell lymphoma (ALCL) is associated with a characteristic chromosomal translocation that generates the oncogenic fusion protein, nucleophosmin-anaplastic lymphoma kinase (NPM-ALK). Methotrexate is a commonly used chemotherapeutic drug in the treatment of multiple cancers due to its inhibition of dihydrofolate reductase (DHFR), which suppresses the synthesis of DNA. In the present study, we found that low-dose methotrexate significantly induced apoptosis in transformed Ba/F3 cells expressing NPM-ALK by inhibiting the activation of signal transducer and activator of transcription factor 3 (STAT3), a critical downstream molecule of NPM-ALK. Although methotrexate prevented the phosphorylation of STAT3, it did not affect the activity of NPM-ALK. A co-treatment with folinic acid prevented the methotrexate-induced inhibition of STAT3 activation and induction of apoptosis, suggesting that methotrexate exerts its cytotoxic effects by depleting tetrahydrofolate (THF) in transformed cells by NPM-ALK. Furthermore, methotrexate induced the down-regulation of the anti-apoptotic protein, MCL-1, DNA damage, and the activation of a p53 tumor suppressor, leading to apoptosis through the inhibition of STAT3. Methotrexate significantly induced apoptosis in ALK inhibitor-resistant cells expressing the NPM-ALK mutant harboring the point mutation, G262R, and in ALCL patient-derived NPM-ALK-positive Ki-JK cells. Collectively, these results demonstrate the potential therapeutic application of methotrexate, which inhibits the activation of STAT3, to NPM-ALK-positive ALCL.

Blockade of crizotinib-induced BCL2 elevation in ALK-positive anaplastic large cell lymphoma triggers autophagy associated with cell death

Anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphomas are tumors that carry translocations involving the ALK gene at the 2p23 locus, leading to the expression of ALK tyrosine kinase fusion oncoproteins. Amongst hematologic malignancies, these lymphomas are particular in that they express very low levels of B-cell lymphoma 2 (BCL2), a recognized inhibitor of apoptosis and autophagy, two processes that share complex interconnections. We have previously shown that treatment of ALK-positive anaplastic large cell lymphoma cells with the ALK tyrosine kinase inhibitor crizotinib induces autophagy as a pro-survival response. Here, we observed that crizotinib-mediated inactivation of ALK caused an increase in BCL2 levels that restrained the cytotoxic effects of the drug. BCL2 downregulation in combination with crizotinib treatment potentiated loss of cell viability through both an increase in autophagic flux and cell death, including apoptosis. More importantly, our data revealed that the blockade of autophagic flux completely reversed impaired cell viability, which demonstrates that excessive autophagy is associated with cell death. We propose that the downregulation of BCL2 protein, which plays a central role in the autophagic and apoptotic machinery, combined with crizotinib treatment may represent a promising therapeutic alternative to current ALK-positive anaplastic large cell lymphoma treatments.

Survival control of malignant lymphocytes by anti-apoptotic MCL-1

Programmed apoptotic cell death is critical to maintain tissue homeostasis and cellular integrity in the lymphatic system. Accordingly, the evasion of apoptosis is a critical milestone for the transformation of lymphocytes on their way to becoming overt lymphomas. The anti-apoptotic BCL-2 family proteins are pivotal regulators of the mitochondrial apoptotic pathway and genetic aberrations in these genes are associated with lymphomagenesis and chemotherapeutic resistance. Pharmacological targeting of BCL-2 is highly effective in certain indolent B-cell lymphomas; however, recent evidence highlights a critical role for the BCL-2 family member MCL-1 in several lymphoma subtypes. MCL-1 is recurrently highly expressed in various kinds of cancer including non-Hodgkin's lymphoma of B- and T-cell origin. Moreover, both indolent and aggressive forms of lymphoma require MCL-1 for lymphomagenesis and for their continued survival. This review summarizes the role of MCL-1 in B- and T-cell lymphoma and discusses its potential as a therapeutic target.

Crizotinib (PF-2341066) induces apoptosis due to downregulation of pSTAT3 and BCL-2 family proteins in NPM-ALK(+) anaplastic large cell lymphoma

Nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) is an aberrant fusion gene product with tyrosine kinase activity and is expressed in substantial subset of anaplastic large cell lymphomas (ALCL). It has been shown that NPM-ALK binds to and activates signal transducer and activator of transcription 3 (STAT3). Although NPM-ALK(+) ALCL overall shows a better prognosis, there is a sub-group of patients who relapses and is resistant to conventional chemotherapeutic regimens. NPM-ALK is a potential target for small molecule kinase inhibitors. Crizotinib (PF-2341066) is a small, orally bioavailable molecule that inhibits growth of tumors with ALK activity as shown in a subgroup of non-small lung cancer patients with EML4-ALK expression. In this study, we have investigated the in vitro effects of Crizotinib in ALCL cell line with NPM-ALK fusion. Crizotinib induced marked downregulation of STAT3 phosphorylation, which was associated with significant apoptotic cell death. Apoptosis induction was attributed to caspase-3 cleavage and marked downregulation of the Bcl-2 family of proteins including MCL-1. These findings implicate that Crizotinib has excellent potential to treat patients with NPM-ALK(+) ALCL through induction of apoptotic cell death and downregulation of major oncogenic proteins in this aggressive lymphoma.

An antiapoptotic BCL-2 family expression index predicts the response of chronic lymphocytic leukemia to ABT-737

The antiapoptotic BCL-2 proteins regulate lymphocyte survival and are over-expressed in lymphoid malignancies, including chronic lymphocytic leukemia. The small molecule inhibitor ABT-737 binds with high affinity to BCL-2, BCL-XL, and BCL-W but with low affinity to MCL-1, BFL-1, and BCL-B. The active analog of ABT-737, navitoclax, has shown a high therapeutic index in lymphoid malignancies; developing a predictive marker for it would be clinically valuable for patient selection or choice of drug combinations. Here we used RT-PCR as a highly sensitive and quantitative assay to compare expression of antiapoptotic BCL-2 genes that are known to be targeted by ABT-737. Our findings reveal that the relative ratio of MCL-1 and BFL-1 to BCL-2 expression provides a highly significant linear correlation with ABT-737 sensitivity (r = 0.6, P < .001). In contrast, antiapoptotic transcript levels, used individually or in combination for high or low affinity ABT-737-binding proteins, could not predict ABT-737 sensitivity. The (MCL-1 + BFL-1)/BCL-2 ratio was validated in a panel of leukemic cell lines subjected to genetic and pharmacologic manipulations. Changes after ABT-737 treatment included increased expression of BFL-1 and BCL-B that may contribute to treatment resistance. This study defines a highly significant BCL-2 expression index for predicting the response of CLL to ABT-737.

MiR-29a down-regulation in ALK-positive anaplastic large cell lymphomas contributes to apoptosis blockade through MCL-1 overexpression

Although deregulated expression of specific microRNAs (miRNAs) has been described in solid cancers and leukemias, little evidence of miRNA deregulation has been reported in ALK-positive (ALK(+)) anaplastic large cell lymphomas (ALCL). These tumors overexpress the major antiapoptotic protein myeloid cell leukemia 1 (MCL-1), a situation that could compensate for the lack of BCL-2. We report that ALK(+) ALCL cell lines and biopsy specimens (n = 20) express a low level of miR-29a and that this down-modulation requires an active NPM-ALK kinase. Murine models (transgenic mice and mouse embryonic fibroblast [MEF] cells), which allow conditional NPM-ALK fusion protein expression, showed an increase of miR-29a expression in the absence of NPM-ALK. Concordant results were observed after the abolition of NPM-ALK kinase activity (siALK or PF-2341066) in NPM-ALK(+) ALCL cell lines. In addition, we showed that low expression of miR-29a, probably through methylation repression, plays an important regulatory role in MCL-1 overexpression that could promote tumor cell survival by inhibiting apoptosis. Enforced miR-29a expression was found to modulate apoptosis through inhibition of MCL-1 expression in ALCL cell lines and in a xenografted model, with a concomitant tumor growth reduction. Thus, synthetic miR-29a represents a potential new tool to affect tumorigenesis in these lymphomas.

Inhibition of MEK/ERK1/2 sensitizes lymphoma cells to sorafenib-induced apoptosis

Interactions between the multi-kinase inhibitor sorafenib and MEK1/2 inhibitors were investigated in DLBCL cells. Sorafenib (3-10 microM) triggered apoptosis in multiple GC and ABC lymphoma cells. Unexpectedly, sorafenib did not cause sustained ERK1/2 inactivation, and in SUDHL-6 and -16 cells, triggered ERK1/2 activation. Marginally toxic MEK1/2 inhibitor concentrations (5 microM PD184352) abrogated ERK1/2 activation in sorafenib-treated cells and synergistically potentiated apoptosis. MEK1 shRNA transfection also significantly increased sorafenib-mediated lethality. Sorafenib/PD184352 co-administration accelerated Mcl-1 down-regulation without up-regulating Bim(EL). Finally, ectopic Mcl-1 expression attenuated sorafenib/PD184352-mediated apoptosis. Together, these findings provide a theoretical basis for potentiating sorafenib anti-lymphoma activity by MEK1/2 inhibitors.

Frequent STAT3 activation is associated with Mcl-1 expression in nasal NK-cell lymphoma

Nasal natural killer (NK)-cell lymphoma was resistant to various antitumor agents. Although high expression of p-glycoprotein has been reported, other molecular mechanism of the chemo-resistance is largely unknown. Activation of STAT3 and expression of major apoptosis-related proteins Bcl-2, Bcl-x, and Mcl-1 were analyzed by immunohistochemistry. Effects of STAT3 inhibitor AG490 on NK-YS cell line were analyzed by Western blotting and flow cytometric apoptosis assay. STAT3 was activated in six of the nine nasal NK-cell lymphomas (67%). In contrast, STAT3 activation was detected in 35% of diffuse large B-cell lymphoma (DLBCL) and in 10% of follicular lymphoma (FL). Frequent activation of STAT3 was significantly correlated with Mcl-1 expression in nasal NK-cell lymphoma, i.e., Mcl-1 was positive in five of six STAT3-active cases and negative in all three STAT3-inactive ones. In DLBCL, not only six out of seven STAT3-active cases (86%) but also eight out of thirteen STAT3-inactive cases (62%) were positive for Mcl-1 expression. Latent membrane protein-1 was positive in four nasal NK-cell lymphomas, among which three cases showed intermediate STAT3 activation. Inhibition of STAT3 activation by JAK inhibitor AG490 decreased Mcl-1 expression and induced apoptosis in STAT3-active NK-YS cells. Serum starvation rather increased the Mcl-1 level in NK-YS cells, and this effect was also canceled by AG490. These results suggest that activation of STAT3-Mcl-1 axis may play a role in the chemotherapy resistance of nasal NK-cell lymphoma. The pathway may be one of the future therapeutic targets of this intractable disease.

Expression of ALK protein, mRNA and fusion transcripts in anaplastic large cell lymphoma

Systemic anaplastic large cell lymphoma (ALCL) can be divided into two subgroups, anaplastic lymphoma kinase (ALK)-positive and ALK-negative, based on the expression of ALK protein. Expression of this protein is due to genetic alterations of ALK at 2p23. Overall, observations on ALK protein, ALK mRNA, ALK-associated genetic alterations and their relationships, to one another are not often reported in the literature. In this study, we investigated the expression of ALK protein, mRNA and fusion transcripts involving ALK and their relationships in ALCL and analyzed formalin-fixed, paraffin-embedded tissues. Forty-five human cases were analyzed with immunohistochemistry for the ALK protein and RT-PCR for ALK mRNA and seven kinds of ALK involved fusion transcripts. Our results showed that the expression of ALK protein, ALK mRNA and ALK fusion transcripts were significantly related to one another (P<0.01). Consistent with the expression of ALK protein, patients presenting with ALK mRNA or ALK involved fusion transcripts were significantly younger than those lacking ALK gene alteration (P<0.01). This study demonstrates expression of both ALK protein and ALK mRNA are positively correlated with expression of ALK-associated fusion transcripts. Combined detection of ALK protein, ALK mRNA and ALK fusion transcripts can complement each other to aid in the diagnosis of ALCL.

Pathobiology of ALK+ anaplastic large-cell lymphoma

Anaplastic large-cell lymphoma (ALCL) was initially recognized on the basis of morphologic features and the consistent expression of CD30. It then became evident that the majority of these tumors are derived from lymphoid cells of T or null immunophenotype. The subsequent finding that t(2;5)(p23;q35) occurs in 40% to 60% of ALCL patients established a distinct clinicopathologic entity. This chromosomal translocation induces the formation of the chimeric protein nucleophosmin-anaplastic lymphoma kinase (NPM-ALK), which possesses significant oncogenic potential resulting from the constitutive activation of the tyrosine kinase ALK. In addition to its specific pathophysiologic events, NPM-ALK-expressing lymphoma presents with consistent clinical manifestations. Only 13 years after the identification of NPM-ALK, tremendous progress has been made in our understanding of this molecule because of the relentless efforts of multiple investigators who have dissected its biologic roles using in vitro and in vivo experimental models. Several upstream modulators, cross-reacting oncogenes, and downstream effectors of NPM-ALK have been identified and characterized. Understanding these interacting oncogenic systems is expected to facilitate the design of new therapeutic strategies and agents. In this review, we briefly discuss ALCL and focus on NPM-ALK.

Inflammatory myofibroblastic tumor: comparison of clinicopathologic, histologic, and immunohistochemical features including ALK expression in atypical and aggressive cases

Inflammatory myofibroblastic tumor (IMT) is a neoplasm of intermediate biologic potential. In this study, we report a subset of IMTs with histologic atypia and/or clinical aggressiveness that were analyzed for clinicopathologic features, outcome, and immunohistochemical expression of anaplastic lymphoma kinase (ALK) and other markers to identify potential pathologic prognostic features. Fifty-nine IMTs with classic morphology (5 cases), atypical histologic features (21 cases), local recurrence (27 cases), and/or metastasis (6 cases) were studied. Immunohistochemistry was performed for ALK1 and other markers (Mib-1, c-Myc, cyclin D1, caspase 3, Bcl-2, Mcl-1, survivin, p27, CD56, p53, MDM-2) using standard techniques. The 59 IMTs had an age at diagnosis ranging from 3 weeks to 74 years (mean 13.2 y, median 11 y, 44% in the first decade). The mean tumor size was 7.8 cm. Sites included the abdomen or pelvis in 64%, lung in 22%, head and neck in 8%, and extremities in 5%. The follow-up ranged from 3 months to 11 years, with a mean of 3.6 years and a median of 3 years. Thirty-three patients had local recurrences, including 13 with multiple local recurrences and 6 patients with both local recurrences and distant metastases. Six patients died of disease, 5 with local recurrences, and 1 with distant metastases. Histologic evolution to a more pleomorphic cellular, spindled, polygonal, or round cell morphologic pattern was observed in 7 cases. Abdominal and pelvic IMTs had a recurrence rate of 85%. Recurrent and metastatic IMTs were larger, with mean diameters of 8.7 and 11 cm, respectively. Cytoplasmic ALK reactivity was seen in 56%. ALK-negative IMTs occurred in older patients (mean age 20.1) years and had greater nuclear pleomorphism, atypia, and atypical mitoses. All 6 metastatic IMTs were ALK-negative. Nuclear expression of p53 was detected in 80% of IMTs overall, but in only 25% of the metastatic subset. There were no significant differences among the subgroups for c-Myc, cyclin D1, MDM-2, Mcl-1, Bcl-2, CD56, p27, caspase 3, or survivin expression. In conclusion, among these 59 IMTs, ALK reactivity was associated with local recurrence, but not distant metastasis, which was confined to ALK-negative lesions. Absent ALK expression was associated with a higher age overall, subtle histologic differences, and death from disease or distant metastases (in a younger subset). Other proliferative, apoptotic, and prognostic markers did not correlate well with morphology or outcome. Thus, ALK reactivity may be a favorable prognostic indicator in IMT and abdominopelvic IMTs recur more frequently.

Differences in survivin location and Bcl-2 expression in CD30+ lymphoproliferative disorders of the skin compared with systemic anaplastic large cell lymphomas: an immunohistochemical study

BACKGROUND

Cutaneous CD30+ lymphoproliferative disorders (LPDs) are a spectrum of disease associated with a favourable prognosis. Systemic anaplastic large cell lymphoma (ALCL), although morphologically and phenotypically similar, differs in clinical presentation and has a less favourable biological behaviour. Dysregulation of apoptosis, the process regulating cell population by programmed death, can explain the differences among these disorders.

OBJECTIVES

We investigated the expression of two inhibitors of apoptosis, survivin and Bcl-2 protein, in serial skin lesion samples from CD30+ LPDs compared with systemic ALCL.

METHODS

Immunohistochemical analysis with antibodies against anaplastic lymphoma kinase (ALK)-1 protein, survivin and Bcl-2 protein was performed in 10 cutaneous CD30+ LPDs (five lymphomatoid papulosis, five ALCL) and 18 systemic ALCLs. Reverse transcription-polymerase chain reaction studies for ALK and ALK/nucleophosmin were also performed.

RESULTS

Cutaneous CD30+ LPDs shared a heterogeneous expression of cytoplasmic survivin with all systemic ALCLs, and of Bcl-2 with systemic ALK- ALCLs; however, they differ from systemic ALK- ALCLs because they lack nuclear survivin (P = 0.045), and from systemic ALK+ ALCLs by a higher expression of Bcl-2 (P = 0.045) and a lack of ALK-1. Overall, coexpression of Bcl-2 and nuclear survivin in CD30+ LPDs was associated with a less favourable disease survival.

CONCLUSIONS

The different patterns of expression of Bcl-2 and survivin in CD30+ LPDs might have an impact on their different biological and clinical behaviour. Moreover, nuclear localization of survivin, similarly to ALK, may be a useful marker for predicting a systemic form of ALCL with cutaneous presentation.

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.

High expression of calcium-binding proteins, S100A10, S100A11 and CALM2 in anaplastic large cell lymphoma

Anaplastic large cell lymphomas (ALCL) are characterised by the presence of CD30-positive large cells, which usually are of T-cell type. Based on the presence or absence of translocations involving the anaplastic lymphoma kinase (ALK) locus, ALCL cases can be divided into two groups. To gain more insight in the biology of ALCL, we applied serial analysis of gene expression (SAGE) on the Karpas299 cell line and identified 25 up- and 19 downregulated genes. Comparison of the differentially expressed genes with DNA copy number changes in Karpas299 revealed that two overexpressed genes, S100A10 and S100A11, were located in an amplicon suggesting that the increased mRNA levels were caused by DNA amplification. Quantitative reverse transcription polymerase chain reaction on 5 ALCL cell lines and 12 ALCL tissues confirmed the SAGE data for 13 out of 14 up- and one out of four downregulated genes. Immunohistochemical staining confirmed the presence of S100A10, a calcium-binding protein, in three out of five ALK+ and all 7 ALK- ALCL cases. S100A11 staining was confirmed in all ALK+ and six of seven ALK- ALCL cases. Three of the upregulated genes represented calcium-binding proteins, which suggest that altered intracellular signaling might be associated with the oncogenesis of ALCL.