Development of anaplastic lymphoma kinase (ALK) small-molecule inhibitors for cancer therapy

Whole transcriptome analysis of canine pheochromocytoma and paraganglioma

Pheochromocytomas and paragangliomas (PPGLs) are neuroendocrine tumors arising from the chromaffin cells in the adrenal medulla and extra-adrenal paraganglia, respectively. Local invasion, concurrent disorders, and metastases prevent surgical removal, which is the most effective treatment to date. Given the current lack of effective medical treatment, there is a need for novel therapeutic strategies. To identify druggable pathways driving PPGL development, we performed RNA sequencing on PPGLs (n = 19) and normal adrenal medullas (NAMs; n = 10) of dogs. Principal component analysis (PCA) revealed that PPGLs clearly clustered apart from NAMs. In total, 4,218 genes were differentially expressed between PPGLs and NAMs. Of these, 232 had a log2 fold change of >3 or < -3, of which 149 were upregulated in PPGLs, and 83 were downregulated. Compared with NAMs, PPGLs had increased expression of genes related to the cell cycle, tumor development, progression and metastasis, hypoxia and angiogenesis, and the Wnt signaling pathway, and decreased expression of genes related to adrenal steroidogenesis. Our data revealed several overexpressed genes that could provide targets for novel therapeutics, such as Ret Proto-Oncogene (RET), Dopamine Receptor D2 (DRD2), and Secreted Frizzled Related Protein 2 (SFRP2). Based on the PCA, PPGLs were classified into 2 groups, of which group 1 had significantly higher Ki67 scores (p = 0.035) and shorter survival times (p = 0.04) than group 2. Increased expression of 1 of the differentially expressed genes between group 1 and 2, pleiotrophin (PTN), appeared to correlate with a more aggressive tumor phenotype. This study has shed light on the transcriptomic profile of canine PPGL, yielding new insights into the pathogenesis of these tumors in dogs, and revealed potential novel targets for therapy. In addition, we identified 2 transcriptionally distinct groups of PPGLs that had significantly different survival times.

Proteomic analysis of hypothalamus in prepubertal and pubertal female goat

The functions of proteins at the onset of puberty in goats remain largely unexplored. To identify the proteins regulating puberty in goats, we analysed protein abundance and pathways in the hypothalamus of female goats. We applied tandem mass tag (TMT) labelling, liquid chromatography-tandem mass spectrometry (LC-MS/MS), and parallel reaction monitoring (PRM) to examine hypothalamus of pubertal (cases; n = 3) and prepubertal (controls; n = 3) goats. We identified 5119 proteins, including 69 differentially abundant proteins (DAPs), of which 35 were upregulated and 34 were downregulated. Fourteen DAPs were randomly selected to verify these results using PRM, and the results were consistent with the TMT quantitative results. DAPs were enriched in MAPK signalling pathway, Ras signalling pathway, Autophagy-animal, Endocytosis, and PI3K/Akt/mTOR signalling pathway categories. These pathways are related to embryogenesis, cell proliferation, cell differentiation, and promoting the release of gonadotropin-releasing hormone (GnRH) in the hypothalamus. In particular, PDGFRβ and MAP3K7 occupied important locations in the protein-protein interaction network. The results demonstrate that DAPs and their related signalling pathways are crucial in regulating puberty in goats. However, further research is needed to explore the functions of DAPs and their pathways to provide new insights into the mechanism of puberty onset. SIGNIFICANCE: In domestic animals, reaching the age of puberty is an event that contributes significantly to lifetime reproductive potential. And the hypothalamus functions directly in the complex systemic changes that control puberty. Our study was the first TMT proteomics analysis on hypothalamus tissues of pubertal goats, which revealed the changes of protein and pathways that are related to the onset of puberty. We identified 69 DAPs, which were enriched in the MAPK signaling pathway, the Ras signaling pathway, and the IGF-1/PI3K/Akt/mTOR pathway, suggesting that these processes were probably involved in the onset of puberty.

Emerging Importance of Tyrosine Kinase Inhibitors against Cancer: Quo Vadis to Cure?

GLOBOCAN 2020 estimated more than 19.3 million new cases, and about 10 million patients were deceased from cancer in 2020. Clinical manifestations showed that several growth factor receptors consisting of transmembrane and cytoplasmic tyrosine kinase (TK) domains play a vital role in cancer progression. Receptor tyrosine kinases (RTKs) are crucial intermediaries of the several cellular pathways and carcinogenesis that directly affect the prognosis and survival of higher tumor grade patients. Tyrosine kinase inhibitors (TKIs) are efficacious drugs for targeted therapy of various cancers. Therefore, RTKs have become a promising therapeutic target to cure cancer. A recent report shows that TKIs are vital mediators of signal transduction and cancer cell proliferation, angiogenesis, and apoptosis. In this review, we discuss the structure and function of RTKs to explore their prime role in cancer therapy. Various TKIs have been developed to date that contribute a lot to treating several types of cancer. These TKI based anticancer drug molecules are also discussed in detail, incorporating their therapeutic efficacy, mechanism of action, and side effects. Additionally, this article focuses on TKIs which are running in the clinical trial and pre-clinical studies. Further, to gain insight into the pathophysiological mechanism of TKIs, we also reviewed the impact of RTK resistance on TKI clinical drugs along with their mechanistic acquired resistance in different cancer types.

Genotype Driven Therapy for Non-Small Cell Lung Cancer: Resistance, Pan Inhibitors and Immunotherapy

Eighty-five percent of patients with lung cancer present with Non-small Cell Lung Cancer (NSCLC). Targeted therapy approaches are promising treatments for lung cancer. However, despite the development of targeted therapies using Tyrosine Kinase Inhibitors (TKI) as well as monoclonal antibodies, the five-year relative survival rate for lung cancer patients is still only 18%, and patients inevitably become resistant to therapy. Mutations in Kirsten Ras Sarcoma viral homolog (KRAS) and epidermal growth factor receptor (EGFR) are the two most common genetic events in lung adenocarcinoma; they account for 25% and 20% of cases, respectively. Anaplastic Lymphoma Kinase (ALK) is a transmembrane receptor tyrosine kinase, and ALK rearrangements are responsible for 3-7% of NSCLC, predominantly of the adenocarcinoma subtype, and occur in a mutually exclusive manner with KRAS and EGFR mutations. Among drug-resistant NSCLC patients, nearly half exhibit the T790M mutation in exon 20 of EGFR. This review focuses on some basic aspects of molecules involved in NSCLC, the development of resistance to treatments in NSCLC, and advances in lung cancer therapy in the past ten years. Some recent developments such as PD-1-PD-L1 checkpoint-based immunotherapy for NSCLC are also covered.

Current Approaches for Personalized Therapy of Soft Tissue Sarcomas

Soft tissue sarcomas (STS) are a highly heterogeneous group of cancers of mesenchymal origin with diverse morphologies and clinical behaviors. While surgical resection is the standard treatment for primary STS, advanced and metastatic STS patients are not eligible for surgery. Systemic treatments, including standard chemotherapy and newer chemical agents, still play the most relevant role in the management of the disease. Discovery of specific genetic alterations in distinct STS subtypes allowed better understanding of mechanisms driving their pathogenesis and treatment optimization. This review focuses on the available targeted drugs or drug combinations based on genetic aberration involved in STS development including chromosomal translocations, oncogenic mutations, gene amplifications, and their perspectives in STS treatment. Furthermore, in this review, we discuss the possible use of chemotherapy sensitivity and resistance assays (CSRA) for the adjustment of treatment for individual patients. In summary, current trends in personalized management of advanced and metastatic STS are based on combination of both genetic testing and CSRA.

Recombinant expression, characterization, and quantification in human cancer cell lines of the Anaplastic Large-Cell Lymphoma-characteristic NPM-ALK fusion protein

Systemic anaplastic large cell lymphoma (ALCL) is an aggressive T-cell lymphoma most commonly seen in children and young adults. The majority of pediatric ALCLs are associated with the t(2;5)(p23;q35) translocation which fuses the Anaplastic Lymphoma Kinase (ALK) gene with the Nucleophosmin (NPM) gene. The NPM-ALK fusion protein is a constitutively-active tyrosine kinase, and plays a major role in tumor pathogenesis. In an effort to advance novel diagnostic approaches and the understanding of the function of this fusion protein in cancer cells, we expressed in E. coli, purified and characterized human NPM-ALK fusion protein to be used as a standard for estimating expression levels in cultured human ALCL cells, a key tool in ALCL pathobiology research. We estimated that NPM-ALK fusion protein is expressed at substantial levels in both Karpas 299 and SU-DHL-1 cells (ca. 4-6 million molecules or 0.5-0.7 pg protein per cell; based on our in-house developed NPM-ALK ELISA; LOD of 40 pM) as compared to the ubiquitous β-actin protein (ca. 64 million molecules or 4.5 pg per lymphocyte). We also compared NPM-ALK/ β-actin ratios determined by ELISA to those independently determined by two-dimensional electrophoresis and showed that the two methods are in good agreement.

The genetic polymorphisms of ZC3HC1 and SMARCA4 are associated with hypertension risk

AIM

In this study, we aimed to evaluate the association between genetic variants of ZC3HC1 and SMARCA4 and hypertension risk in the Chinese Han population.

METHODS

The Agena MassAssary platform was used to determine the genotypes of eight SNPs in ZC3HC1 and SMARCA4 from 350 hypertension patients and 483 healthy controls. Chi-squared tests and genetic model were used to evaluate the associations. Odds ratios and 95% confidence intervals were calculated using unconditional logistic regression. The statistical power of this study was estimated through the Power and Sample Size Calculation online software.

RESULT

In the genetic model analysis, we identified that the SNP of rs1464890 in ZC3HC1 was associated with a 0.68-fold decreased risk of hypertension in the codominant model and 0.65-fold decreased risk in the dominant model. Rs4507692 in ZC3HC1 was associated with a 0.69-fold decreased risk of hypertension in the codominant model and 0.66-fold decreased risk in the dominant model. The genotype "G/A-A/A" of rs11879293 and the genotype "G/T-T/T" of rs1122608 in SMARCA4 were significantly associated with decreasing the hypertension risk. In addition, the "A_rs2242487 T_rs1464890 T_rs4507692 " ZC3HC1 haplotype was associated with a decreased risk of hypertension.

CONCLUSION

The present study suggested that ZC3HC1 and SMARCA4 polymorphism may conducive to play a protective role against the hypertension risk.

Targeting ALK in Cancer: Therapeutic Potential of Proapoptotic Peptides

ALK is a receptor tyrosine kinase, associated with many tumor types as diverse as anaplastic large cell lymphomas, inflammatory myofibroblastic tumors, breast and renal cell carcinomas, non-small cell lung cancer, neuroblastomas, and more. This makes ALK an attractive target for cancer therapy. Since ALK–driven tumors are dependent for their proliferation on the constitutively activated ALK kinase, a number of tyrosine kinase inhibitors have been developed to block tumor growth. While some inhibitors are under investigation in clinical trials, others are now approved for treatment, notably in ALK-positive lung cancer. Their efficacy is remarkable, however limited in time, as the tumors escape and become resistant to the treatment through different mechanisms. Hence, there is a pressing need to target ALK-dependent tumors by other therapeutic strategies, and possibly use them in combination with kinase inhibitors. In this review we will focus on the therapeutic potential of proapoptotic ALK-derived peptides based on the dependence receptor properties of ALK. We will also try to make a non-exhaustive list of several alternative treatments targeting ALK-dependent and independent signaling pathways.

Targeting ALK in pediatric RMS does not induce antitumor activity in vivo

PURPOSE

The anaplastic lymphoma kinase (ALK) has been demonstrated to be a valid clinical target in diseases such as anaplastic large cell lymphoma and non-small cell lung cancer. Recent studies have indicated that ALK is overexpressed in pediatric rhabdomyosarcoma (RMS) and hence we hypothesized that this kinase may be a suitable candidate for therapeutic intervention in this tumor.

METHODS

We evaluated the expression of ALK in a panel of pediatric RMS cell lines and patient-derived xenografts (PDX), and sensitivity to ALK inhibitors was assessed both in vitro and in vivo.

RESULTS

Essentially, all RMS lines were sensitive to crizotinib, NVP-TAE684 or LDK-378 in vitro, and molecular analyses demonstrated inhibition of RMS cell proliferation following siRNA-mediated reduction of ALK expression. However, in vivo PDX studies using ALK kinase inhibitors demonstrated no antitumor activity when used as single agents or when combined with standard of care therapy (vincristine, actinomycin D and cyclophosphamide). More alarmingly, however, crizotinib actually accelerated the growth of these tumors in vivo.

CONCLUSIONS

While ALK appears to be a relevant target in RMS in vitro, targeting this kinase in vivo yields no therapeutic efficacy, warranting extreme caution when considering the use of these agents in pediatric RMS patients.

Latest perspectives of orally bioavailable 2,4-diarylaminopyrimidine analogues (DAAPalogues) as anaplastic lymphoma kinase inhibitors: discovery and clinical developments

The course of anaplastic lymphoma kinase (ALK)-rearranged non-small-cell lung cancer (NSCLC) therapy has improved impressively. The Food and Drug Administration (FDA) has approved crizotinib (Xalkori, Pfizer) as a first-in-class tyrosine kinase inhibitor (TKI) that demonstrated a substantial objective response rate (ORR) and remarkable progression-free survival (PFS). However, acquired resistance to crizotinib is still a major concern especially as the central nervous system (CNS) remains the most common sites of relapse. To combat disease resistance, limited PFS and poor CNS exposure exhibited by crizotinib (Xalkori, Pfizer) led to the discovery of numerous next generation ALK-TKIs and surprisingly most of them are 2,4-Diarylaminopyrimidine Analogues (DAAPalogues). To date, DAAPalogues have been investigated extensively to display their superior potency against numerous kinase targets especially ALK/ROS1. This review describes hit-to-drug evolution strategies, activity spectra, milestones related to medicinal chemistry discovery efforts and scalable synthetic pathways of clinically emerging DAAPalouges which are either progressing as investigational or preclinical candidates. In addition, the significance of DAAPalogues to treat the patients with ALK+-NSCLC in clinical settings has been detailed. This review is beneficial for medicinal chemists and researchers contributing to discovering ALK-TKIs to overcome existing issues related to DAAPalouges in the drug discovery process.

ALK expression plays different roles in anaplastic large-cell lymphomas and outcome of crizotinib use in relapsed/refractory ALK+ patients in a Chinese population

The prognostic value of anaplastic lymphoma kinase (ALK) expression in patients with anaplastic large-cell lymphoma (ALCL) remains controversial. Data on the clinical features of ALCL in a Chinese population are limited. We retrospectively reviewed 1293 patients with pathologically diagnosed lymphoma at Guangdong General Hospital from June 2007 through August 2016. We evaluated the incidence of ALCL, clinical characteristics, survival status, and outcome of crizotinib use in four relapsed/refractory ALK-positive patients. Among the 1293 patients, 1193 (92.3%) were non-Hodgkin's lymphoma, and 53 (4.4%) of whom were ALCL. Of the 50 ALCL patients, with a median age of 34 years, were evaluated. Among them, 33 (66.0%) were ALK-positive and 17 (34.0%) were ALK-negative. Significantly, more patients younger than 40 years old were ALK-positive than ALK-negative (66.7 vs. 23.5%; P = 0.003). The 5-year progression-free survival (PFS) for ALK-positive and ALK-negative patients were 61 and 11%, and the 5-year overall survival (OS) were 70 and 22%, respectively. Median PFS and OS were significantly better for patients with ALK-positive than ALK-negative (60.1 vs. 9.4 months, P = 0. 017; not reached vs. 32.7 months, P = 0.021). Multivariate analyses identified ALK expression, stage, and bone marrow involvement as independent prognostic factors for PFS and OS. Four relapsed ALK-positive patients were treated with crizotinib and two died. Our results suggest that ALK expression has different prognostic significance in patients with ALCL. Mechanisms underlying early relapse after chemotherapy and resistance to crizotinib need further investigation.

T-cell lymphomas, a challenging disease: types, treatments, and future

T-cell lymphomas are rare and aggressive malignancies associated with poor outcome, often because of the development of resistance in the lymphoma against chemotherapy as well as intolerance in patients to the established and toxic chemotherapy regimens. In this review article, we discuss the epidemiology, pathophysiology, current standard of care, and future treatments of common types of T-cell lymphomas, including adult T-cell leukemia/lymphoma, angioimmunoblastic T-cell lymphoma, anaplastic large-cell lymphoma, aggressive NK/T-cell lymphoma, and cutaneous T-cell lymphoma.

Discovery of Brigatinib (AP26113), a Phosphine Oxide-Containing, Potent, Orally Active Inhibitor of Anaplastic Lymphoma Kinase

In the treatment of echinoderm microtubule-associated protein-like 4 (EML4)-anaplastic lymphoma kinase positive (ALK+) non-small-cell lung cancer (NSCLC), secondary mutations within the ALK kinase domain have emerged as a major resistance mechanism to both first- and second-generation ALK inhibitors. This report describes the design and synthesis of a series of 2,4-diarylaminopyrimidine-based potent and selective ALK inhibitors culminating in identification of the investigational clinical candidate brigatinib. A unique structural feature of brigatinib is a phosphine oxide, an overlooked but novel hydrogen-bond acceptor that drives potency and selectivity in addition to favorable ADME properties. Brigatinib displayed low nanomolar IC50s against native ALK and all tested clinically relevant ALK mutants in both enzyme-based biochemical and cell-based viability assays and demonstrated efficacy in multiple ALK+ xenografts in mice, including Karpas-299 (anaplastic large-cell lymphomas [ALCL]) and H3122 (NSCLC). Brigatinib represents the most clinically advanced phosphine oxide-containing drug candidate to date and is currently being evaluated in a global phase 2 registration trial.

Molecular genetics of childhood, adolescent and young adult non-Hodgkin lymphoma

Molecular genetic abnormalities are ubiquitous in non-Hodgkin lymphoma (NHL), but genetic changes are not yet used to define specific lymphoma subtypes. Certain recurrent molecular genetic abnormalities in NHL underlie molecular pathogenesis and/or are associated with prognosis or represent potential therapeutic targets. Most molecular genetic studies of B- and T-NHL have been performed on adult patient samples, and the relevance of many of these findings for childhood, adolescent and young adult NHL remains to be demonstrated. In this review, we focus on NHL subtypes that are most common in young patients and emphasize features actually studied in younger NHL patients. This approach highlights what is known about NHL genetics in young patients but also points to gaps that remain, which will require cooperative efforts to collect and share biological specimens for genomic and genetic analyses in order to help predict outcomes and guide therapy in the future.

An integrated molecular modeling approach for in silico design of new tetracyclic derivatives as ALK inhibitors

Anaplastic lymphoma kinase (ALK), a promising therapeutic target for treatment of human cancers, is a receptor tyrosine kinase that instigates the activation of several signal transduction pathways. In the present study, in silico methods have been employed in order to explore the structural features and functionalities of a series of tetracyclic derivatives displaying potent inhibitory activity toward ALK. Initially docking was performed using GLIDE 5.6 to probe the bioactive conformation of all the compounds and to understand the binding modes of inhibitors. The docking results revealed that ligand interaction with Met 1199 plays a crucial role in binding of inhibitors to ALK. Further to establish a robust 3D-QSAR model using CoMFA and CoMSIA methods, the whole dataset was divided into three splits. Model obtained from Split 3 showed high accuracy ([Formula: see text] of 0.700 and 0.682, [Formula: see text] of 0.971 and 0.974, [Formula: see text] of 0.673 and 0.811, respectively for CoMFA and CoMSIA). The key structural requirements for enhancing the inhibitory activity were derived from CoMFA and CoMSIA contours in combination with site map analysis. Substituting small electronegative groups at Position 8 by replacing either morpholine or piperidine rings and maintaining hydrophobic character at Position 9 in tetracyclic derivatives can enhance the inhibitory potential. Finally, we performed molecular dynamics simulations in order to investigate the stability of protein ligand interactions and MM/GBSA calculations to compare binding free energies of co-crystal ligand and newly designed molecule N1. Based on the coherence of outcome of various molecular modeling studies, a set of 11 new molecules having potential predicted inhibitory activity were designed.

Association of genetic variants with atrial fibrillation

Recent genome-wide association studies (GWASs) identified various genes and loci that confer susceptibility to coronary artery disease or myocardial infarction among Caucasian populations. As myocardial ischemia is an important risk factor for atrial fibrillation, we hypothesized that certain polymorphisms may contribute to the genetic susceptibility to atrial fibrillation through affecting the susceptibility to coronary artery disease. The aim of the present study was to examine the possible association of atrial fibrillation in Japanese individuals with 29 polymorphisms identified as susceptibility loci for coronary artery disease or myocardial infarction in the meta-analyses of GWASs in Caucasian populations. The study subjects comprised 5,470 Japanese individuals (305 subjects with atrial fibrillation and 5,165 controls). Genotypes for 29 polymorphisms were determined by a method that combines the polymerase chain reaction and sequence-specific oligonucleotide probes with suspension array technology. Comparisons of the allele frequencies by the χ² test revealed that rs599839 (G→A) of the proline/serine-rich coiled-coil 1 gene (PSRC1, P=0.0084) and rs11556924 (C→T, Arg363His) of the zinc finger, C3HC-type containing 1 gene (ZC3HC1, P=0.0076) were significantly (P<0.01) associated with atrial fibrillation. Multivariable logistic regression analysis with adjustment for age, gender, body mass index, estimated glomerular filtration rate, and the prevalence of smoking, hypertension, diabetes mellitus, and dyslipidemia revealed that rs599839 (P=0.0043; odds ratio, 1.56; dominant model) and rs11556924 (P=0.0043; odds ratio, 1.93; dominant model) were significantly associated with atrial fibrillation, with the minor G and T alleles, respectively, representing risk factors for this condition. PSRC1 and ZC3HC1 may thus be susceptibility loci for atrial fibrillation in Japanese individuals.

Association of Zinc Finger, C3HC-Type Containing 1 (ZC3HC1) rs11556924 Genetic Variant With Hypertension in a Finnish Population, the TAMRISK Study

In a recent genome-wide association study, the zinc finger, C3HC-type containing 1 (ZC3HC1) polymorphism was strongly associated with coronary artery disease (CAD) by an unknown mechanism. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is related with CAD through low-density lipoprotein (LDL) metabolism. The association of both of the above genetic variants with hypertension was studied in a Finnish 50-year-old cohort.A total of 325 hypertensive cases and 444 nonhypertensive controls were obtained from the Tampere adult population cardiovascular risk study. Samples were genotyped for ZC3HC1 rs11556924 and PCSK9 rs11206510 polymorphisms using Competitive Allele Specific PCR technique. A subpopulation that had available follow-up data from ages of 40, 45, and 50 years was also analyzed.ZC3HC1 rs11556924 (C > T) genotype CC was associated with hypertension compared with the T-allele carriers (P = 0.013). PCSK9 rs11206510 (T > C) genotype was not associated with hypertension. Its major TT-genotype was associated with higher total cholesterol (P = 0.044) and LDL (P = 0.029) compared with the C-allele.We report for the first time that ZC3HC1 rs11556924 was associated with essential hypertension in 50-year-old patients. Although PCSK9 rs11206510 was not associated with hypertension, our study confirms its association with serum cholesterol levels.

The oncogenic transcription factor IRF4 is regulated by a novel CD30/NF-κB positive feedback loop in peripheral T-cell lymphoma

Peripheral T-cell lymphomas (PTCLs) are generally aggressive non-Hodgkin lymphomas with poor overall survival rates following standard therapy. One-third of PTCLs express interferon regulatory factor-4 (IRF4), a tightly regulated transcription factor involved in lymphocyte growth and differentiation. IRF4 drives tumor growth in several lymphoid malignancies and has been proposed as a candidate therapeutic target. Because direct IRF4 inhibitors are not clinically available, we sought to characterize the mechanism by which IRF4 expression is regulated in PTCLs. We demonstrated that IRF4 is constitutively expressed in PTCL cells and drives Myc expression and proliferation. Using an inhibitor screen, we identified nuclear factor κB (NF-κB) as a candidate regulator of IRF4 expression and cell proliferation. We then demonstrated that the NF-κB subunits p52 and RelB were transcriptional activators of IRF4. Further analysis showed that activation of CD30 promotes p52 and RelB activity and subsequent IRF4 expression. Finally, we showed that IRF4 transcriptionally regulates CD30 expression. Taken together, these data demonstrate a novel positive feedback loop involving CD30, NF-κB, and IRF4; further evidence for this mechanism was demonstrated in human PTCL tissue samples. Accordingly, NF-κB inhibitors may represent a clinical means to disrupt this feedback loop in IRF4-positive PTCLs.

Efficacy of crizotinib inhibiting specific molecular pathways in non-small-cell lung carcinoma

The US FDA granted approval for crizotinib as the first-line treatment for patients with echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase rearranged metastatic non-small-cell lung cancer, on November 20, 2013. Crizotinib is a customized and improved therapeutic option for patients with non-small-cell lung cancer that enhances overall survival without increasing toxicity. In the future, new targeted therapies may achieve additional indications for treating patients with lung cancer. This article summarizes data from crizotinib studies.

Advances in understanding the pathogenesis of systemic anaplastic large cell lymphomas

The currently used 2008 World Health Organization classification recognizes two types of systemic anaplastic large T cell lymphoma according to ALK protein expression in tumour cells. First, the 'anaplastic large cell lymphoma, ALK positive' (ALK(+) ALCL) that is characterized by the presence of ALK gene rearrangements and consequent ALK protein expression, and, second, the 'anaplastic large cell lymphoma, ALK negative' (ALK(-) ALCL) that is a provisional entity lacking ALK protein expression but cannot be distinguished morphologically from ALK(+) ALCL. In this review we summarize the current knowledge on the genetic lesions and biological features that underlie the pathogenesis of ALK(+) and the ALK(-) ALCL and that can lead to the use of targeted anti-cancer agents.

Anaplastic large cell lymphomas: ALK positive, ALK negative, and primary cutaneous

Anaplastic large cell lymphomas (ALCLs) comprise a group of CD30-positive non-Hodgkin lymphomas that generally are of T-cell origin and share common morphologic and phenotypic characteristics. The World Health Organization recognizes 3 entities: primary cutaneous ALCL (pcALCL), anaplastic lymphoma kinase (ALK)-positive ALCL, and, provisionally, ALK-negative ALCL. Despite overlapping pathologic features, these tumors differ in clinical behavior and genetics. pcALCL presents in the skin and, while it may involve locoregional lymph nodes, rarely disseminates. Outcomes typically are excellent. ALK-positive ALCL and ALK-negative ALCL are systemic diseases. ALK-positive ALCLs consistently have chromosomal rearrangements involving the ALK gene with varied gene partners, and generally have a favorable prognosis. ALK-negative ALCLs lack ALK rearrangements and their genetic and clinical features are more variable. A subset of ALK-negative ALCLs has rearrangements in or near the DUSP22 gene and has a favorable prognosis similar to that of ALK-positive ALCL. DUSP22 rearrangements also are seen in a subset of pcALCLs. In this review, we discuss the clinical, morphologic, phenotypic, genetic, and biological features of ALCLs.

Protein kinase and HDAC inhibitors from the endophytic fungus Epicoccum nigrum

A chemical investigation of the endophytic fungus Epicoccum nigrum isolated from leaves of Mentha suaveolens collected in Morocco resulted in the isolation of five new polyketides, epicocconigrones A and B (1 and 2), 3-methoxyepicoccone B (3), 3-methoxyepicoccone (4), and 2,3,4-trihydroxy-6-(methoxymethyl)-5-methylbenzaldehyde (5), together with five known compounds (6-10). The structures of the new compounds were unambiguously determined by extensive analysis of the 1D and 2D NMR and mass spectroscopic data. Compounds 1 and 10 showed potent inhibition of at least 15 protein kinases with IC50 values ranging from 0.07 to 9.00 μM. Moreover, compounds 1 and 10 inhibited histone deacetylase (HDAC) activities with IC50 values of 9.8 and 14.2 μM, respectively. A preliminary structure-activity relationship is discussed. Interestingly, compounds 1 and 10 exert mainly cytostatic effects in human lymphoma RAJI and U-937 cell lines.

The potent oncogene NPM-ALK mediates malignant transformation of normal human CD4(+) T lymphocytes

With this study we have demonstrated that in vitro transduction of normal human CD4(+) T lymphocytes with NPM-ALK results in their malignant transformation. The transformed cells become immortalized and display morphology and immunophenotype characteristic of patient-derived anaplastic large-cell lymphomas. These unique features, which are strictly dependent on NPM-ALK activity and expression, include perpetual cell growth, proliferation, and survival; activation of the key signal transduction pathways STAT3 and mTORC1; and expression of CD30 (the hallmark of anaplastic large-cell lymphoma) and of immunosuppressive cytokine IL-10 and cell-surface protein PD-L1/CD274. Implantation of NPM-ALK-transformed CD4(+) T lymphocytes into immunodeficient mice resulted in formation of tumors indistinguishable from patients' anaplastic large-cell lymphomas. Our findings demonstrate that the key aspects of human carcinogenesis closely recapitulating the features of the native tumors can be faithfully reproduced in vitro when an appropriate oncogene is used to transform its natural target cells; this in turn points to the fundamental role in malignant cell transformation of potent oncogenes expressed in the relevant target cells. Such transformed cells should permit study of the early stages of carcinogenesis, and in particular the initial oncogene-host cell interactions. This experimental design could also be useful for studies of the effects of early therapeutic intervention and likely also the mechanisms of malignant progression.

Malignant transformation of CD4+ T lymphocytes mediated by oncogenic kinase NPM/ALK recapitulates IL-2-induced cell signaling and gene expression reprogramming

Anaplastic lymphoma kinase (ALK), physiologically expressed only by nervous system cells, displays a remarkable capacity to transform CD4(+) T lymphocytes and other types of nonneural cells. In this study, we report that activity of nucleophosmin (NPM)/ALK chimeric protein, the dominant form of ALK expressed in T cell lymphomas (TCLs), closely resembles cell activation induced by IL-2, the key cytokine supporting growth and survival of normal CD4(+) T lymphocytes. Direct comparison of gene expression by ALK(+) TCL cells treated with an ALK inhibitor and IL-2-dependent ALK(-) TCL cells stimulated with the cytokine revealed a very similar, albeit inverse, gene-regulation pattern. Depending on the analysis method, up to 67% of the affected genes were modulated in common by NPM/ALK and IL-2. Based on the gene expression patterns, Jak/STAT- and IL-2-signaling pathways topped the list of pathways identified as affected by both IL-2 and NPM/ALK. The expression dependence on NPM/ALK and IL-2 of the five selected genes-CD25 (IL-2Rα), Egr-1, Fosl-1, SOCS3, and Irf-4-was confirmed at the protein level. In both ALK(+) TCL and IL-2-stimulated ALK(-) TCL cells, CD25, SOCS3, and Irf-4 genes were activated predominantly by the STAT5 and STAT3 transcription factors, whereas transcription of Egr-1 and Fosl-1 was induced by the MEK-ERK pathway. Finally, we found that Egr-1, a protein not associated previously with either IL-2 or ALK, contributes to the cell proliferation. These findings indicate that NPM/ALK transforms the target CD4(+) T lymphocytes, at least in part, by using the pre-existing, IL-2-dependent signaling pathways.

The ZC3HC1 rs11556924 polymorphism is associated with increased carotid intima-media thickness in patients with rheumatoid arthritis

Introduction

Rheumatoid arthritis (RA) is a complex polygenic disease associated with chronic inflammation, accelerated atherosclerosis and increased cardiovascular (CV) mortality. A recent meta-analysis has described the ZC3HC1 rs11556924 polymorphism as one of the most important signals associated with coronary artery disease (CAD) in non-rheumatic Caucasian individuals. In this study we evaluated the potential association of this gene polymorphism with subclinical atherosclerosis assessed by the evaluation of carotid intima-media thickness (cIMT) in RA patients.

Methods

This study included 502 RA patients from Northern Spain. The ZC3HC1 rs11556924 polymorphism was genotyped with TaqMan single-nucleotide polymorphism (SNP) genotyping assays (C__31283062_10) in a 7900HT real-time polymerase chain reaction (PCR) system. cIMT was also assessed in these patients by carotid ultrasonography (US) technology.

Results

RA patients carrying the TT genotype had significantly higher cIMT values than those homozygous for the CC genotype (mean ± standard deviation (SD): 0.76 ± 0.18 mm and mean ± SD: 0.71 ± 0.16 mm respectively; P = 0.03) even after adjusting the results for sex, age at the time of US study, follow-up time and traditional CV risk factors (P = 0.04) evidencing that the effect conferred by ZC3HC1 rs11556924 polymorphism is independent of the traditional CV risk factors.

Conclusion

Our results indicate that ZC3HC1 rs11556924 polymorphism is associated with subclinical atherosclerosis in RA.

Prognostic significance and therapeutic potential of the activation of anaplastic lymphoma kinase/protein kinase B/mammalian target of rapamycin signaling pathway in anaplastic large cell lymphoma

BACKGROUND

Activation of the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway has been demonstrated to be involved in nucleophosmin-anaplastic lymphoma kinase (NPM-ALK)-mediated tumorigenesis in anaplastic large cell lymphoma (ALCL) and correlated with unfavorable outcome in certain types of other cancers. However, the prognostic value of AKT/mTOR activation in ALCL remains to be fully elucidated. In the present study, we aim to address this question from a clinical perspective by comparing the expressions of the AKT/mTOR signaling molecules in ALCL patients and exploring the therapeutic significance of targeting the AKT/mTOR pathway in ALCL.

METHODS

A cohort of 103 patients with ALCL was enrolled in the study. Expression of ALK fusion proteins and the AKT/mTOR signaling phosphoproteins was studied by immunohistochemical (IHC) staining. The pathogenic role of ALK fusion proteins and the therapeutic significance of targeting the ATK/mTOR signaling pathway were further investigated in vitro study with an ALK + ALCL cell line and the NPM-ALK transformed BaF3 cells.

RESULTS

ALK expression was detected in 60% of ALCLs, of which 79% exhibited the presence of NPM-ALK, whereas the remaining 21% expressed variant-ALK fusions. Phosphorylation of AKT, mTOR, 4E-binding protein-1 (4E-BP1), and 70 kDa ribosomal protein S6 kinase polypeptide 1 (p70S6K1) was detected in 76%, 80%, 91%, and 93% of ALCL patients, respectively. Both phospho-AKT (p-AKT) and p-mTOR were correlated to ALK expression, and p-mTOR was closely correlated to p-AKT. Both p-4E-BP1 and p-p70S6K1 were correlated to p-mTOR, but were not correlated to the expression of ALK and p-AKT. Clinically, ALK + ALCL occurred more commonly in younger patients, and ALK + ALCL patients had a much better prognosis than ALK-ALCL cases. However, expression of p-AKT, p-mTOR, p-4E-BP1, or p-p70S6K1 did not have an impact on the clinical outcome. Overexpression of NPM-ALK in a nonmalignant murine pro-B lymphoid cell line, BaF3, induced the cells to become cytokine-independent and resistant to glucocorticoids (GCs). Targeting AKT/mTOR inhibited growth and triggered the apoptotic cell death of ALK + ALCL cells and NPM-ALK transformed BaF3 cells, and also reversed GC resistance induced by overexpression of NPM-ALK.

CONCLUSIONS

Overexpression of ALK due to chromosomal translocations is seen in the majority of ALCL patients and endows them with a much better prognosis. The AKT/mTOR signaling pathway is highly activated in ALK + ALCL patients and targeting the AKT/mTOR signaling pathway might confer a great therapeutic potential in ALCL.

ALK as a paradigm of oncogenic promiscuity: different mechanisms of activation and different fusion partners drive tumors of different lineages

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase protein implicated in a variety of hematological malignancies and solid tumors. Since the identification of the ALK gene in 1994 as the target of the t(2;5) chromosomal translocation in anaplastic large cell lymphoma, ALK has been proven a remarkably promiscuous oncogene. ALK contributes to the development of a notable assortment of tumor types from different lineages, including hematolymphoid, mesenchymal, epithelial and neural tumors, through a variety of genetic mechanisms: gene fusions, activating point mutations, and gene amplification. Recent developments led to significant diagnostic and therapeutic advances, including efficient diagnostic tests and ALK-targeting agents readily available in the clinical setting. This review addresses some therapeutic considerations of ALK-targeted agents and the biologic implications of ALK oncogenic promiscuity, but the main points discussed are: 1) the variety of mechanisms that result in activation of the ALK oncogene, with emphasis on the promiscuous partnerships demonstrated in chromosomal rearrangements; 2) the diversity of tumor types of different lineages in which ALK has been implicated as a pathogenic driver; and 3) the different diagnostic tests available to identify ALK-driven tumors, and their respective indications.

New insights into the genetics of neuroblastoma

Neuroblastoma is a genetically and clinically heterogeneous tumor of childhood, arising from precursor cells of the sympathetic nervous system. It is still a challenging cancer for pediatric oncology, as some tumors will spontaneously regress, while others will become refractory to all forms of therapy. The clinical course of this disease is greatly influenced by both patient age and the genetic abnormalities that occur within the tumors. MYCN (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian)) amplification and loss of chromosome 11q heterozygosity have been known to be indicative of poor prognosis. In this article, we review how mutations and structural alterations in specific genes contribute to inheritable predisposition to neuroblastoma and/or to aggressive disease pathogenesis, as well as implications for diagnosis and therapy. These genes include PHOX2B (paired-like homeobox 2b), ALK (anaplastic lymphoma receptor tyrosine kinase), and ATRX (alpha thalassemia/mental retardation syndrome X-linked).

Non-Hodgkin's B-cell lymphoma: advances in molecular strategies targeting drug resistance

Non-Hodgkin's lymphoma (NHL) is a heterogeneous class of cancers displaying a diverse range of biological phenotypes, clinical behaviours and prognoses. Standard treatments for B-cell NHL are anthracycline-based combinatorial chemotherapy regimens composed of cyclophosphamide, doxorubicin, vincristine and prednisolone. Even though complete response rates of 40-50% with chemotherapy can be attained, a substantial proportion of patients relapse, resulting in 3-year overall survival rates of about 30%. Relapsed lymphomas are refractory to subsequent treatments with the initial chemotherapy regimen and can exhibit cross-resistance to a wide variety of anticancer drugs. The emergence of acquired chemoresistance thus poses a challenge in the clinic preventing the successful treatment and cure of disseminated B-cell lymphomas. Gene-expression analyses have increased our understanding of the molecular basis of chemotherapy resistance and identified rational targets for drug interventions to prevent and treat relapsed/refractory diffuse large B-cell lymphoma. Acquisition of drug resistance in lymphoma is in part driven by the inherent genetic heterogeneity and instability of the tumour cells. Due to the genetic heterogeneity of B-cell NHL, many different pathways leading to drug resistance have been identified. Successful treatment of chemoresistant NHL will thus require the rational design of combinatorial drugs targeting multiple pathways specific to different subtypes of B-cell NHL as well as the development of personalized approaches to address patient-to-patient genetic heterogeneity. This review highlights the new insights into the molecular basis of chemorefractory B-cell NHL that are facilitating the rational design of novel strategies to overcome drug resistance.

ALK receptor activation, ligands and therapeutic targeting in glioblastoma and in other cancers

The intracellular anaplastic lymphoma kinase (ALK) fragment shows striking homology with members of the insulin receptor family and was initially identified as an oncogenic fusion protein resulting from a translocation in lymphoma and more recently in a range of cancers. The full-length ALK transmembrane receptor of ~220 kDa was identified based on this initial work. This tyrosine kinase receptor and its ligands, the growth factors pleiotrophin (PTN) and midkine (MK) are highly expressed during development of the nervous system and other organs. Each of these genes has been implicated in malignant progression of different tumor types and shown to alter phenotypes as well as signal transduction in cultured normal and tumor cells. Beyond its role in cancer, the ALK receptor pathway is thought to contribute to nervous system development, function, and repair, as well as metabolic homeostasis and the maintenance of tissue regeneration. ALK receptor activity in cancer can be up-regulated by amplification, overexpression, ligand binding, mutations in the intracellular domain of the receptor and by activity of the receptor tyrosine phosphatase PTPRz. Here we discuss the evidence for ligand control of ALK activity as well as the potential prognostic and therapeutic implications from gene expression and functional studies. An analysis of 18 published gene expression data sets from different cancers shows that overexpression of ALK, its smaller homolog LTK (leukocyte tyrosine kinase) and the ligands PTN and MK in cancer tissues from patients correlate significantly with worse course and outcome of the disease. This observation together with preclinical functional studies suggests that this pathway could be a valid therapeutic target for which complementary targeting strategies with small molecule kinase inhibitors as well as antibodies to ligands or the receptors may be used.

Clinical feature of anaplastic lymphoma kinase-mutated neuroblastoma

PURPOSE

Anaplastic lymphoma kinase (ALK) has recently been identified as a gene conferring a predisposition for neuroblastoma. We have analyzed tyrosine kinase domain mutations and amplification/expression of the ALK gene and focused on clinical features of neuroblastoma cases with ALK aberrations.

METHODS

The frequency of ALK mutations, copy number gain, and expression were analyzed in 538 neuroblastoma tumors derived from 361 cases, including 161 cases detected by mass screening. These cases were analyzed according to clinicopathologic features including the International Neuroblastoma Staging System and patient outcomes.

RESULTS

Three cases (0.8%) had ALK amplification, and 16 cases (5.2%) had missense mutations at positions F1174, F1245, D1249, and R1275. Among them, 7 cases were diagnosed at more than 14 months of age, and 11 cases were infants, including 9 cases detected by mass screening and 1 multiple neuroblastoma with a germline mutation. Of the 11 infants, 3 cases relapsed, and 1 case died of disease. Among cases detected by screening, activated ALK cases showed significantly worse prognosis (P = .002). Of 7 older cases, 5 had MYC amplifications, and 5 died of disease. The expression levels of ALK were up-regulated in cases with unfavorable outcomes. In cases with activated ALK neuroblastoma, survival rates of patients detected by screening were significantly better than those in the clinically detected group (P = .025).

CONCLUSIONS

The results of the present study support the hypothesis that activated ALK tumors represent a specific subset of neuroblastomas. These tumors usually develop in infants and may have a high capacity for recurrence.

Research progresses in the pathogenesis of anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) is a distinct subset of T-cell non-Hodgkin's lymphoma. As a consequence of its low incidence, general pathogenic consideration of ALCL is lacking. In this review, we summarize the pathogenesis, epidemiology, clinical manifestations, and treatment of ALCL, so as to better understand key stages of the development of this disease and provide valuable information for future treatment.

Targeted inactivation of nuclear interaction partner of ALK disrupts meiotic prophase

NIPA (nuclear interaction partner of ALK) is an F-box-like protein that monitors the timing of mitotic entry. Constitutively active NIPA delays mitotic entry by preventing accumulation of nuclear cyclin B1. Here, we have investigated the consequences of Nipa inactivation by using a conditional knockout strategy. Nipa-deficient animals are viable but show a lower birth rate and reduced body weight. Furthermore, Nipa-deficient males are sterile owing to a block of spermatogenesis during meiotic prophase. Whereas Nipa-/- mouse embryonic fibroblasts show no severe phenotype, Nipa-/- spermatocytes arrest during stage IV of the epithelial cycle with subsequent TUNEL-positive apoptosis resulting from improper synapsis, defects in the repair of DNA double-stranded breaks and synaptonemal complex formation. Moreover, we show nuclear accumulation of cyclin B1 with a subsequent premature increase in G2/M kinase activity in Nipa-/- spermatocytes. Together, these results reveal a novel role for NIPA in meiosis.

The emerging role of ALK inhibitors in the treatment of advanced non-small cell lung cancer

INTRODUCTION

Most NSCLC patients are diagnosed in the advanced stage of the disease. Recently, chemotherapeutic agents have reached a plateau of effectiveness. Increased understanding of cancer biology has revealed several potential therapeutic strategies that have led to marketing of new biologic agents. The echinoderm microtubule-associated protein like-4-anaplastic lymphoma kinase (EML4-ALK) fusion oncogene represents one of the newest molecular targets in NSCLC, identifying a subset of NSCLC patients characterized by distinct clinicopathological features.

AREAS COVERED

The available results concerning ALK inhibitors for the treatment of advanced NSCLC patients. An electronic search was used to retrieve the articles addressing this topic.

EXPERT OPINION

In a pivotal Phase I clinical trial, crizotinib (PF-02341066), a small-molecule ALK inhibitor, demonstrated impressive antitumor activity in the majority of NSCLC patients with ALK fusions. Phase III randomized trials investigating crizotinib in this subgroup of patients are ongoing. If the results from these large international trials confirm the efficacy of crizotinib in the subset of patients, the next few years could see the treatment of advanced NSCLC patients with ALK fusions. Specific inhibitors would realize the so called personalized medicine in subsets of this disease.

Anaplastic Lymphoma Kinase Aberrations in Rhabdomyosarcoma: Clinical and Prognostic Implications

Purpose

The aim of this study is to investigate anaplastic lymphoma kinase (ALK) protein expression and underlying genetic aberrations in rhabdomyosarcoma (RMS), with special attention to clinical and prognostic implications.

Patients and Methods

A total of 189 paraffin-embedded RMS tumor specimens from 145 patients were collected on tissue microarray. ALK protein expression was evaluated by immunohistochemistry. ALK gene (2p23) copy number and translocations were determined by in situ hybridization. cDNA sequencing of the receptor tyrosine kinase domain of the ALK gene was assessed in 43 samples.

Results

Strong cytoplasmic ALK protein expression was more frequently observed in alveolar RMS (ARMS) than in embryonal RMS (ERMS) (81% v 32%, respectively; P < .001). ALK gene copy number gain was detected in the vast majority of ARMS (88%), compared with 52% of ERMS (P < .001). ALK copy number correlated with protein expression in primary tumors (n = 107). We identified one point mutation (2%) and seven tumors harboring whole exon deletions (16%). In ERMS, specific ALK gain in the primary tumor correlated with metastatic disease (100% in metastatic disease v 29% in nonmetastatic disease; P = .004) and poor disease-specific survival (5-year disease-specific survival: 62% v 82% for nonspecific or no gain; P = .046).

Conclusion

Because ALK aberrations on genomic and protein levels are frequently found in RMSs, in particular ARMS, and are associated with disease progression and outcome in ERMS, ALK may play a role in tumor biology and may provide a potential therapeutic target for these tumors. Future research should aim at the oncogenic role of ALK and the potential effect of ALK inhibitors in RMS.

High anaplastic lymphoma kinase immunohistochemical staining in neuroblastoma and ganglioneuroblastoma is an independent predictor of poor outcome

Anaplastic lymphoma kinase (ALK) mutations occur in 3% to 11% of neuroblastoma (NBL) cases and are associated with high ALK levels. However, high ALK levels appear to be a mutation-independent hallmark of NBL. Evidence about the prognostic relevance of ALK mutations and ALK tumor positivity in patients with NBL has been inconclusive. In this study, we investigated the prognostic relevance of ALK positivity by IHC and ALK mutation status by PCR sequencing in 71 NBL, 12 ganglioneuroblastoma (GNBL), and 20 ganglioneuroma samples in a multivariate model. ALK mutations were present in 2 of 72 NBL and 2 of 12 GNBL samples, which all contained many ALK-positive cells (>50%). In addition, half of all NBL samples showed ALK positivity in most (>50%) of tumor cells, whereas half of the GNBL showed staining in <20% of the tumor cells. In most ganglioneuroma samples, a low percentage of tumor cells stained positive for ALK, which mainly involved ganglion cells. Higher percentages of ALK-positive cells in NBL and GNBL patient samples correlated with inferior survival in univariate and multivariate analyses with established prognostic factors, such as stage, age, and MYCN status. In conclusion, ALK positivity by IHC is an independent, poor prognostic factor in patients with GNBL and NBL. ALK IHC is an easy test suitable for future risk stratification in patients with NBL and GNBL.

ALK and NSCLC: Targeted therapy with ALK inhibitors

For many years treatment for advanced or metastatic non-small cell lung cancer (NSCLC) has employed chemotherapy regimens for patient care, with limited effect. Five-year survival rates for these patients are not encouraging. However, for a subgroup of these patients, there have been radical changes over recent years. Our understanding of the basic pathology behind NSCLC at the molecular level has offered up a host of new molecularly targeted therapies, which are revolutionizing this area of cancer care. Results from recent clinical trials provide hope for NSCLC patients harboring oncogenic translocations involving the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase. Just as inhibition of the breakpoint cluster region-ABL complex has changed the face of chronic myeloid leukemia diagnosis, oncogenic ALK fusions offer a step forward in the diagnosis and treatment of ALK-positive NSCLC. This article discusses the current knowledge and potential implications concerning ALK inhibitors and NSCLC.

Emerging importance of ALK in neuroblastoma

Since the original descriptions of gain-of function mutations in anaplastic lymphoma kinase (ALK), interest in the role of this receptor tyrosine kinase in neuroblastoma development and as a potential therapeutic target has escalated. As a group, the activating point mutations in full-length ALK, found in approximately 8% of all neuroblastoma tumors, are distributed evenly across different clinical stages. However, the most frequent somatic mutation, F1174L, is associated with amplification of the MYCN oncogene. This combination of features appears to confer a worse prognosis than MYCN amplification alone, suggesting a cooperative effect on neuroblastoma formation by these two proteins. Indeed, F1174L has shown more potent transforming activity in vivo than the second most common activating mutation, R1275Q, and is responsible for innate and acquired resistance to crizotinib, a clinically relevant ALK inhibitor that will soon be commercially available. These advances cast ALK as a bona fide oncoprotein in neuroblastoma and emphasize the need to understand ALK-mediated signaling in this tumor. This review addresses many of the current issues surrounding the role of ALK in normal development and neuroblastoma pathogenesis, and discusses the prospects for clinically effective targeted treatments based on ALK inhibition.

The receptor tyrosine kinase Alk controls neurofibromin functions in Drosophila growth and learning

Anaplastic Lymphoma Kinase (Alk) is a Receptor Tyrosine Kinase (RTK) activated in several cancers, but with largely unknown physiological functions. We report two unexpected roles for the Drosophila ortholog dAlk, in body size determination and associative learning. Remarkably, reducing neuronal dAlk activity increased body size and enhanced associative learning, suggesting that its activation is inhibitory in both processes. Consistently, dAlk activation reduced body size and caused learning deficits resembling phenotypes of null mutations in dNf1, the Ras GTPase Activating Protein-encoding conserved ortholog of the Neurofibromatosis type 1 (NF1) disease gene. We show that dAlk and dNf1 co-localize extensively and interact functionally in the nervous system. Importantly, genetic or pharmacological inhibition of dAlk rescued the reduced body size, adult learning deficits, and Extracellular-Regulated-Kinase (ERK) overactivation dNf1 mutant phenotypes. These results identify dAlk as an upstream activator of dNf1-regulated Ras signaling responsible for several dNf1 defects, and they implicate human Alk as a potential therapeutic target in NF1.

Neurofibromatosis-1 (NF1) syndrome is a common (1/3,000 births) genetic disorder affecting multiple organ systems, including the nervous system. Its clinical features include short stature, learning disabilities, and several types of benign and malignant tumors. NF1 is caused by mutations that inactivate the NF1 gene, a crucial negative regulator of Ras signaling. Although unregulated Ras signaling is a hallmark of NF1, the specific Ras signaling pathways responsible for disease development remain largely unknown. The Drosophila and human Nf1 genes are highly conserved; and, as in patients, mutant flies are smaller than usual and present deficient learning. Here, we identified the Drosophila Receptor Tyrosine Kinase dAlk as a negative regulator of organismal growth and olfactory learning. We show that excessive dAlk activation results in growth and learning defects similar to those of Nf1 mutants. Genetic suppression studies and pharmacological inhibition indicate dAlk as a critical upstream activator of Nf1-regulated neuronal Ras/ERK signals that contribute to size determination and learning. Importantly, our results strongly suggest that Alk represents a novel, highly specific, and promising therapeutic target in human NF1.

Anaplastic lymphoma kinase in human cancer

The receptor tyrosine kinases (RTKs) play a critical role, controlling cell proliferation, survival, and differentiation of normal cells. Their pivotal function has been firmly established in the pathogenesis of many cancers as well. The anaplastic lymphoma kinase (ALK), a transmembrane RTK, originally identified in the nucleophosmin (NPM)-ALK chimera of anaplastic large cell lymphoma, has emerged as a novel tumorigenic player in several human cancers. In this review, we describe the expression of the ALK-RTK, its related fusion proteins, and their molecular mechanisms of activation. Novel tailored strategies are briefly illustrated for the treatment of ALK-positive neoplasms.