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- IntroductionAnaplastic lymphoma kinase-positive (ALK ϩ ) anaplastic large cell lymphoma (ALCL) is now recognized as a distinct entity in the World Health Organization (WHO) classification of hematopoietic tumors 1,2 and is characterized by the expression of an oncogenic fusion protein involving the ALK tyrosine kinase receptor. 3,4 Most of the activated pathways downstream to this fusion protein with a constitutive tyrosine kinase activity have been characterized and play major roles in lymphomagenesis in ALK ϩ ALCL, controlling key cellular processes such as proliferation, survival, and cell migration (for review see Chiarle et al 5 ). Another characteristic of ALK ϩ ALCLs is the lack or low expression of the antiapoptotic proteins BCL-2 and BCL-XL, suggesting a possible explanation for their relatively good prognosis. However, these tumors overexpressed MCL-1 (myeloid cell leukemia-1), an oncogene of particular interest, belonging to BCL-2 family of apoptosisregulating proteins, 6 and also involved in programming differentiation 7 and promoting cell viability. 8 MCL-1 expression could compensate for the lack of immunohistochemically detectable BCL-2 and BCL-XL expression in ALK ϩ ALCL. [9][10][11] Some studies have suggested that the Jak-STAT and PI3K pathways activated in ALK ϩ tumors could be involved in up-regulating MCL-1 but other pathways at the posttranscriptional level, such as microRNAs, might also contribute to its high expression in ALK ϩ ALCL cases (see reviews by Akgul 12 and Michels et al 13 ).Micro-RNAs (miRNAs) are small noncoding RNAs that regulate target gene expression posttranscriptionally through base pairing within the 3Ј-UTR regions of the target messenger RNAs and inducing their degradation, translational inhibition, or both of the encoded proteins. 14,15 MiRNAs play key regulator roles in fundamental biologic processes including cell differentiation, apoptosis, cell proliferation, organ development, and hematopoiesis (see review by Kluiver et al 16 ). family members have been shown to be down-regulated in several hematopoietic neoplasms, including chronic lymphocytic leukemia with poor prognosis, 17 acute myeloid leukemia, 18 and mantle cell lymphoma, 19 as well as solid cancers such as lung cancer, 20 hepatocellular carcinoma, 21 and invasive breast cancer. 22 More particularly, miR-29a, miR-29b, or both directly target the antiapoptotic protein MCL-1 in cholangiocarcinoma, 23 hepatocellular carcinoma, 21 and acute myeloid leukemia (AML). 18 However, to date, only one study has addressed th...

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NPM-ALK (nucleophosmin-anaplastic lymphoma kinase) and TPM3-ALK (nonmuscular tropomyosin 3-anaplastic lymphoma kinase) are oncogenic tyrosine kinases implicated in the pathogenesis of human ALK-positive lymphoma. We report here the development of novel conditional mouse models for ALK-induced lymphomagenesis, with the use of the tetracycline regulatory system under the control of the EμSRα enhancer/promoter. The expression of either oncogene resulted in the arrest of the differentiation of early B cells and lymphomagenesis. We also observed the development of skin keratoacanthoma lesions, probably because of aberrant ALK expression in keratinocytes. The inactivation of the ALK oncogene on doxycycline treatment was sufficient to induce sustained regression of both hematopoietic tumors and skin disease. Importantly, treatment with the specific ALK inhibitor (PF-2341066) also reversed the pathologic states, showing the value of these mouse models for the validation of ALK tyrosine kinase inhibitors. Thus, our results show (1) that NPM-ALK and TPM3-ALK oncogenes are sufficient for lymphoma/leukemia development and required for tumor maintenance, hence validating ALK as potentially effective therapeutic target; and (2) for the first time, in vivo, the equal tumorigenic potential of the NPM-ALK and TPM3-ALK oncogenic tyrosine kinases. Our models offer a new tool to investigate in vivo the molecular mechanisms associated with ALK-induced lymphoproliferative disorders.

Nucleophosmin-anaplastic lymphoma kinase (NPM–ALK) is a tyrosine kinase oncogene responsible for the pathogenesis of the majority of human ALK-positive lymphomas. We recently reported that it activated the Rac1 GTPase in anaplastic large-cell lymphoma (ALCL), leading to Rac-dependent formation of active invadopodia required for invasiveness. Herein, we went further into the study of this pathway and used the inhibitor of Rac, NSC23766, to validate its potential as a molecular target in ALCL in vitro and in vivo in a xenograft model and in a conditional model of NPM–ALK transgenic mice. Our data demonstrate that Rac regulates important effectors of NPM–ALK-induced transformation such as Erk1/2, p38 and Akt. Moreover, inhibition of Rac signaling abrogates NPM–ALK-elicited disease progression and metastasis in mice, highlighting the potential of small GTPases and their regulators as additional therapic targets in lymphomas.

IntroductionSystemic anaplastic large-cell lymphoma (ALCL) is an aggressive peripheral T-cell lymphoma. There are 2 types of ALCL, classified as anaplastic lymphoma kinase (ALK)-positive (ALK ϩ ) or ALKnegative (ALK Ϫ ) depending on whether the receptor tyrosine kinase ALK is expressed. ALK is activated most frequently through the nonrandom t(2;5) chromosome translocation, resulting in the fusion of the nucleophosmin (NPM) gene from the 5q35 locus to the 2p23 region that encodes ALK. 1,2 ALK ϩ ALCLs are characterized by frequent extranodal colonization, particularly in the skin (reported in 20%-30% of cases), and this is associated with a negative prognosis. 1 The diagnosis of cutaneous dissemination in ALK ϩ ALCL is not always easy and, in some cases, the original histopathological classification is one of "non-malignant inflammatory disease." 3 Interestingly, an insect bite could be the trigger for cutaneous ALK ϩ lymphoma metastases. Our group reported 5 cases of systemic ALK ϩ ALCL in which skin lesions presented after an insect bite at the onset of the disease, postulating that bite-associated Ags could result in an influx of T lymphocytes, some of them bearing the t(2;5) translocation. 4 The subsequent release of cytokines leading to skin inflammation at the site of the bite could act as a "second hit" eliciting activation of T lymphocytes, which would then express the oncogenic NPM-ALK protein and undergo uncontrolled proliferation and transformation. 4 ALK ϩ ALCL patients also present with an inflammatory syndrome characterized by high fever, lymphadenopathy or neutrophilia, release of various circulating inflammatory chemokines such as IL-8, 5 and expression of skin-inflammatory biomarkers such as the alarmins heat-shock protein 90 (HSP90), HSP70, 6 S100A8, or A11. 7 Recent studies have highlighted a role for IL-8 in mediating cutaneous skin inflammation and human keratinocyte hyperplasia associated with acanthosis (thickening of the skin). 8 IL-8 secreted by hyperplasic keratinocytes increases T-lymphocyte migration into the skin across both the vascular endothelium and the subendothelial matrix. 9 The high-mobility-group box-1 (HMGB-1) alarmin, also called amphoterin, is a highly conserved component of eukaryotic nuclei. 10 Interestingly, it can also be released from necrotic and tumoral cells, where it is considered an inflammatory cytokine. T-and B-cell non-Hodgkin lymphoma cells express and release high levels of HMGB-1. 11 Its extracellular form binds to inflammatory receptors, such as the receptor for advanced glycation end products (RAGE) and TLR. 12,13 HMGB-1 has also been shown to regulate matrix metallopeptidase-9 (MMP-9) levels via NF-Brelated pathways. 14,15 In ALK ϩ ALCL, we have demonstrated that MMP-9 is required for NPM-ALK ϩ cell invasiveness. 16 Moreover, MMPs stimulate protease-activated receptors (PARs). 17 Activation of PAR-2 results in the production of various cytokines and chemokines by keratinocytes, 18 leading to epidermic inflammation via increased NF-B p65 phosphorylation an...

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Headaches account for up to 4.5% of emergency department visits, where they present a significant diagnostic challenge. While primary headaches are benign, secondary headaches can be life-threatening. It is essential to rapidly differentiate between primary and secondary headaches as the latter require immediate diagnostic work-up. Current assessment relies on subjective measures; time constraints can result in overuse of diagnostic neuroimaging, prolonging diagnosis, and adding to economic burden. There is therefore an unmet need for a time- and cost-efficient, quantitative triaging tool to guide further diagnostic testing. Routine blood tests may provide important diagnostic and prognostic biomarkers indicating underlying headache causes. In this retrospective study (approved by the UK Medicines and Healthcare products Regulatory Agency Independent Scientific Advisory Committee for Clinical Practice Research Datalink (CPRD) research [20_000173]), UK CPRD real-world data from patients (n = 121,241) presenting with headache from 1993–2021 were used to generate a predictive model based on a machine learning (ML) approach for primary versus secondary headaches. A ML-based predictive model was constructed using two different methods (logistic regression and random forest) and the following predictors were evaluated: ten standard measurements of complete blood count (CBC) test, 19 ratios of the ten CBC test parameters, and patient demographic and clinical characteristics. The model’s predictive performance was assessed using a set of cross-validated model performance metrics. The final predictive model showed modest predictive accuracy using the random forest method (balanced accuracy: 0.7405). The sensitivity, specificity, false negative rate (incorrect prediction of secondary headache as primary headache), and false positive rate (incorrect prediction of primary headache as secondary headache) were 58%, 90%, 10%, and 42%, respectively. The ML-based prediction model developed could provide a useful time- and cost-effective quantitative clinical tool to facilitate the triaging of patients presenting to the clinic with headache.