A multivariable prediction model for pegvisomant dosing: monotherapy and in combination with long-acting somatostatin analogues

BACKGROUND

Effective treatment of acromegaly with pegvisomant (PEGV), a growth hormone receptor antagonist, requires an appropriate dose titration. PEGV doses vary widely among individual patients, and various covariates may affect its dosing and pharmacokinetics.

OBJECTIVE

To identify predictors of the PEGV dose required to normalize insulin-like growth factor I (IGF-I) levels during PEGV monotherapy and in combination with long-acting somatostatin analogues (LA-SSAs).

DESIGN

Two retrospective cohorts (Rotterdam + Liège Acromegaly Survey (LAS), total n = 188) were meta-analyzed as a form of external replication to study the predictors of PEGV dosing in addition to LA-SSA, the LAS (n = 83) was used to study the predictors of PEGV monotherapy dosing. Multivariable regression models were used to identify predictors of the PEGV dose required to normalize IGF-I levels.

RESULTS

For PEGV dosing in combination with LA-SSA, IGF-I levels, weight, height and age, were associated with the PEGV normalization dosage (P ≤ 0.001, P ≤ 0.001, P = 0.028 and P = 0.047 respectively). Taken together, these characteristics predicted the PEGV normalization dose correctly in 63.3% of all patients within a range of ±60 mg/week (21.3% within a range of ±20 mg/week). For monotherapy, only weight was associated with the PEGV normalization dose (P ≤ 0.001) and predicted this dosage correctly in 77.1% of all patients within a range of ±60 mg/week (31.3% within a range of ±20 mg/week).

CONCLUSION

In this study, we show that IGF-I levels, weight, height and age can contribute to define the optimal PEGV dose to normalize IGF-I levels in addition to LA-SSA. For PEGV monotherapy, only the patient's weight was associated with the IGF-I normalization PEGV dosage.

Cabergoline for Cushing's disease: a large retrospective multicenter study

OBJECTIVE

The efficacy of cabergoline in Cushing's disease (CD) is controversial. The aim of this study was to assess the efficacy and tolerability of cabergoline in a large contemporary cohort of patients with CD.

DESIGN

We conducted a retrospective multicenter study from thirteen French and Belgian university hospitals.

METHODS

Sixty-two patients with CD received cabergoline monotherapy or add-on therapy. Symptom score, biological markers of hypercortisolism and adverse effects were recorded.

RESULTS

Twenty-one (40%) of 53 patients who received cabergoline monotherapy had normal urinary free cortisol (UFC) values within 12 months (complete responders), and five of these patients developed corticotropic insufficiency. The fall in UFC was associated with significant reductions in midnight cortisol and plasma ACTH, and with clinical improvement. Compared to other patients, complete responders had similar median baseline UFC (2.0 vs 2.5xULN) and plasma prolactin concentrations but received lower doses of cabergoline (1.5 vs 3.5 mg/week, P < 0.05). During long-term treatment (>12 months), cabergoline was withdrawn in 28% of complete responders because of treatment escape or intolerance. Overall, sustained control of hypercortisolism was obtained in 23% of patients for 32.5 months (19-105). Nine patients on steroidogenesis inhibitors received cabergoline add-on therapy for 19 months (1-240). Hypercortisolism was controlled in 56% of these patients during the first year of treatment with cabergoline at 1.0 mg/week (0.5-3.5).

CONCLUSIONS

About 20-25% of CD patients are good responders to cabergoline therapy allowing long-term control of hypercortisolism at relatively low dosages and with acceptable tolerability. No single parameter, including the baseline UFC and prolactin levels, predicted the response to cabergoline.

MRI follow-up is unnecessary in patients with macroprolactinomas and long-term normal prolactin levels on dopamine agonist treatment

OBJECTIVE

Both antitumor and antisecretory efficacies of dopamine agonists (DA) make them the first-line treatment of macroprolactinomas. However, there is no guideline for MRI follow-up once prolactin is controlled. The aim of our study was to determine whether a regular MRI follow-up was necessary in patients with long-term normal prolactin levels under DA.

PATIENTS AND METHODS

We conducted a retrospective multicenter study (Marseille, Paris La Pitie Salpetriere and Nancy, France; Liege, Belgium) including patients with macroprolactinomas (largest diameter: >10 mm and baseline prolactin level: >100 ng/mL) treated by dopamine agonists, and regularly followed (pituitary MRI and prolactin levels) during at least 48 months once normal prolactin level was obtained.

RESULTS

In total, 115 patients were included (63 men and 52 women; mean age at diagnosis: 36.3 years). Mean baseline prolactin level was 2224 ± 6839 ng/mL. No significant increase of tumor volume was observed during the follow-up. Of the 21 patients (18%) who presented asymptomatic hemorrhagic changes of the macroprolactinoma on MRI, 2 had a tumor increase (2 and 7 mm in the largest size). Both were treated by cabergoline (1 mg/week) with normal prolactin levels obtained for 6 and 24 months. For both patients, no further growth was observed on MRI during follow-up at the same dose of cabergoline.

CONCLUSION

No significant increase of tumor size was observed in our patients with controlled prolactin levels on DA. MRI follow-up thus appears unnecessary in patients with biologically controlled macroprolactinomas.

[A Familial Non Medullary Thyroid Carcinoma (FNMTC) : a clinical and genetic update]

The syndrome of Familial Non Medullary Thyroid Carcinoma (FNMTC) includes two or more patients with an isolated non-medullary thyroid cancer (papillary, follicular, anaplastic) within the same family. To diagnose FNMTC, the clinician must exclude a syndromic presentation such as the syndromes of Cowden, Gardner or Werner, and the Carney Complex. Up to now, a hundred families with FNMTC have been genetically studied, including forms with (Ch19p13.2) or without oxyphilia (Ch2q21), in association with a multinodular goiter (Ch14q32), or with a renal cancer (Ch1q21). Several candidate genes of susceptibility have been proposed: SRGAP1, NKX2-1, FOXE1 and HABP2. So far, it is considered that familial cases represent less than 5 % of thyroid cancers. Although rare, these cases represent a unique opportunity to improve our understanding of thyroid cancer. The identification of candidate genes will enrich our knowledge of thyroid cancer pathophysiology. Based on the literature and our experience of the follow-up of eight families with FNMTC, we discuss epidemiological, clinical, pathological and genetic aspects of FNMTC with a view to improve the diagnosis and treatment of this disease.

Therapeutic targeting of the MYC signal by inhibition of histone chaperone FACT in neuroblastoma

Amplification of the MYCN oncogene predicts treatment resistance in childhood neuroblastoma. We used a MYC target gene signature that predicts poor neuroblastoma prognosis to identify the histone chaperone FACT (facilitates chromatin transcription) as a crucial mediator of the MYC signal and a therapeutic target in the disease. FACT and MYCN expression created a forward feedback loop in neuroblastoma cells that was essential for maintaining mutual high expression. FACT inhibition by the small-molecule curaxin compound CBL0137 markedly reduced tumor initiation and progression in vivo. CBL0137 exhibited strong synergy with standard chemotherapy by blocking repair of DNA damage caused by genotoxic drugs, thus creating a synthetic lethal environment in MYCN-amplified neuroblastoma cells and suggesting a treatment strategy for MYCN-driven neuroblastoma.

GPR101 Mutations are not a Frequent Cause of Congenital Isolated Growth Hormone Deficiency

Patients with Xq26.3 microduplication present with X-linked acrogigantism (X-LAG) syndrome, an early-childhood form of gigantism due to marked growth hormone (GH) hypersecretion from mixed GH-PRL adenomas and hyperplasia. The microduplication includes GPR101, which is upregulated in patients' tumor tissue. The GPR101 gene codes for an orphan G protein coupled receptor that is normally highly expressed in the hypothalamus. Our aim was to determine whether GPR101 loss of function mutations or deletions could be involved in patients with congenital isolated GH deficiency (GHD). Taking advantage of the cohort of patients from the GENHYPOPIT network, we studied 41 patients with unexplained isolated GHD. All patients had Sanger sequencing of the GPR101 gene and array comparative genome hybridization (aCGH) to look for deletions. Functional studies (cell culture with GH secretion measurements, cAMP response) were performed. One novel GPR101 variant, c.589 G>T (p.V197L), was seen in the heterozygous state in a patient with isolated GHD. In silico analysis suggested that this variant could be deleterious. Functional studies did not show any significant difference in comparison with wild type for GH secretion and cAMP response. No truncating, frameshift, or small insertion-deletion (indel) GPR101 mutations were seen in the 41 patients. No deletion or other copy number variation at chromosome Xq26.3 was found on aCGH. We found a novel GPR101 variant of unknown significance, in a patient with isolated GH deficiency. Our study did not identify GPR101 abnormalities as a frequent cause of GH deficiency.

Persistent low levels of serum hCG due to heterophilic mouse antibodies: an unrecognized pitfall in the diagnosis of trophoblastic disease

Phantom hCG refers to persistent mild elevations of hCG, leading physicians to unnecessary treatments whereas neither a true hCG nor a trophoblastic disease is present. We report the case of a 23-year-old woman with persistent low levels of serum hCG detected one month after miscarriage. As choriocarcinoma was suspected, a chemotherapy trial of methotrexate was prescribed, without any hCG reduction. Subsequently, laparoscopy ruled out a trophoblastic residue and the patient was referred to the Endocrine Unit for further investigations. While low levels of hCG were still detected in serum, no hCG was detected in the urine. In addition, when serum was processed in a HBT tube for revealing heterophilic antibodies, hCG was no longer detected. Such finding indicated the presence of phantom hCG due to heterophilic mouse antibodies interaction. This case raises the need of clinico-biological discussion to avoid inappropriate therapeutic decisions. Based on this case experience and after review of the literature, we suggest that current gynecological protocols for the diagnosis and treatment of trophoblastic disease should consider the inclusion of urinary hCG and/or a test for serum heterophilic antibodies when appropriate.

Targeting MYCN-Driven Transcription By BET-Bromodomain Inhibition

PURPOSE

Targeting BET proteins was previously shown to have specific antitumoral efficacy against MYCN-amplified neuroblastoma. We here assess the therapeutic efficacy of the BET inhibitor, OTX015, in preclinical neuroblastoma models and extend the knowledge on the role of BRD4 in MYCN-driven neuroblastoma.

EXPERIMENTAL DESIGN

The efficacy of OTX015 was assessed in in vitro and in vivo models of human and murine MYCN-driven neuroblastoma. To study the effects of BET inhibition in the context of high MYCN levels, MYCN was ectopically expressed in human and murine cells. The effect of OTX015 on BRD4-regulated transcriptional pause release was analyzed using BRD4 and H3K27Ac chromatin immunoprecipitation coupled with DNA sequencing (ChIP-Seq) and gene expression analysis in neuroblastoma cells treated with OTX015 compared with vehicle control.

RESULTS

OTX015 showed therapeutic efficacy against preclinical MYCN-driven neuroblastoma models. Similar to previously described BET inhibitors, concurrent MYCN repression was observed in OTX015-treated samples. Ectopic MYCN expression, however, did not abrogate effects of OTX015, indicating that MYCN repression is not the only target of BET proteins in neuroblastoma. When MYCN was ectopically expressed, BET inhibition still disrupted MYCN target gene transcription without affecting MYCN expression. We found that BRD4 binds to super-enhancers and MYCN target genes, and that OTX015 specifically disrupts BRD4 binding and transcription of these genes.

CONCLUSIONS

We show that OTX015 is effective against mouse and human MYCN-driven tumor models and that BRD4 not only targets MYCN, but specifically occupies MYCN target gene enhancers as well as other genes associated with super-enhancers. Clin Cancer Res; 22(10); 2470-81. ©2015 AACR.

RNA expression signatures and posttranscriptional regulation in diabetic nephropathy

In the last decade, the integration of molecular approaches including transcriptome and miRNome analyses uncovered pathological mechanisms involved in the progression of diabetic nephropathy (DN). Using these techniques, molecular marker candidates [both messenger RNA (mRNA) and miRNA] have also been identified which may enable the characterization of patients at high risk for progression to end-stage renal disease. The results of such studies are urgently needed for a molecular definition of DN and for targeted treatment to improve patient care. The heterogeneity of kidney tissue and the minute amounts of RNA isolated from renal biopsies remain a challenge for omics-studies. Nevertheless, several studies have succeeded in the identification of RNA expression signatures in patients with diabetes and kidney disease. These studies show a reduced expression of growth factors such as VEGF and EGF, and an increased expression of matrix components and matrix-modulating enzymes, an activation of specific NF-κB modules, inflammatory pathways and the complement system. microRNAs are involved in the fine-tuning of mRNA abundance by binding to the 3' untranslated region of a target mRNA, which leads in most cases to translational repression or mRNA cleavage and a decrease in protein output. Here, we review the platforms used for miRNA expression profiling and ways to predict miRNA targets and functions. Several miRNAs have been shown to be involved in the pathogenesis of DN (e.g. miR-21, miR-192, miR-215, miR-216a, miR-29, let-7, miR-25, miR-93, etc.). Functional studies provide evidence that miRNAs are not only diagnostic tools but also represent potential therapeutic targets in DN.

Glutathione biosynthesis is upregulated at the initiation of MYCN-driven neuroblastoma tumorigenesis

The MYCN gene is amplified and overexpressed in a large proportion of high stage neuroblastoma patients and has been identified as a key driver of tumorigenesis. However, the mechanism by which MYCN promotes tumor initiation is poorly understood. Here we conducted metabolic profiling of pre-malignant sympathetic ganglia and tumors derived from the TH-MYCN mouse model of neuroblastoma, compared to non-malignant ganglia from wildtype littermates. We found that metabolites involved in the biosynthesis of glutathione, the most abundant cellular antioxidant, were the most significantly upregulated metabolic pathway at tumor initiation, and progressively increased to meet the demands of tumorigenesis. A corresponding increase in the expression of genes involved in ribosomal biogenesis suggested that MYCN-driven transactivation of the protein biosynthetic machinery generated the necessary substrates to drive glutathione biosynthesis. Pre-malignant sympathetic ganglia from TH-MYCN mice had higher antioxidant capacity and required glutathione upregulation for cell survival, when compared to wildtype ganglia. Moreover, in vivo administration of inhibitors of glutathione biosynthesis significantly delayed tumorigenesis when administered prophylactically and potentiated the anticancer activity of cytotoxic chemotherapy against established tumors. Together these results identify enhanced glutathione biosynthesis as a selective metabolic adaptation required for initiation of MYCN-driven neuroblastoma, and suggest that glutathione-targeted agents may be used as a potential preventative strategy, or as an adjuvant to existing chemotherapies in established disease.

MYCN-targeting miRNAs are predominantly downregulated during MYCN‑driven neuroblastoma tumor formation

MYCN is a transcription factor that plays key roles in both normal development and cancer. In neuroblastoma, MYCN acts as a major oncogenic driver through pleiotropic effects regulated by multiple protein encoding genes as well as microRNAs (miRNAs). MYCN activity is tightly controlled at the level of transcription and protein stability through various mechanisms. Like most genes, MYCN is further controlled by miRNAs, but the full complement of all miRNAs implicated in this process has not been determined through an unbiased approach. To elucidate the role of miRNAs in regulation of MYCN, we thus explored the MYCN-miRNA interactome to establish miRNAs controlling MYCN expression levels. We combined results from an unbiased and genome-wide high-throughput miRNA target reporter screen with miRNA and mRNA expression data from patients and a murine neuroblastoma progression model. We identified 29 miRNAs targeting MYCN, of which 12 miRNAs are inversely correlated with MYCN expression or activity in neuroblastoma tumor tissue. The majority of MYCN-targeting miRNAs in neuroblastoma showed a decrease in expression during murine MYCN-driven neuroblastoma tumor development. Therefore, we provide evidence that MYCN-targeting miRNAs are preferentially downregulated in MYCN-driven neuroblastoma, suggesting that MYCN negatively controls the expression of these miRNAs, to safeguard its expression.

[CONTROVERSIES REGARDING THE ACCURACY AND LIMITATIONS OF FROZEN SECTION IN THYROID PATHOLOGY: AN EVIDENCE-BASED ASSESSMENT]

Palpable thyroid nodules are present clinically in 4-7% of the population and their prevalence increases to 50%-67% when using high-resolution neck ultrasonography. By contrast, thyroid carcinoma (TC) represents only 5-20% of these nodules, which underlines the need for an appropriate approach to avoid unnecessary surgery. Frozen section (PS) has been used for more than 40 years in thyroid surgery to establish the diagnosis of malignancy. However, a controversy persists regarding the accuracy of FS and its place in thyroid pathology has changed with the emergence of fine-needle aspiration (FNA). A PubMed Medline and SpringerLink search was made covering the period from January 2000 to June 2012 to assess the accuracy of ES, its limitations and indications for the diagnosis of thyroid nodules. Twenty publications encompassing 8.567 subjects were included in our study. The average value of TC among thyroid nodules in analyzed studies was 15.5 %. ES ability to detect cancer expressed by its sensitivity (Ss) was 67.5 %. More than two thirds of the authors considered PS useful exclusively in the presence of doubtful ENA and for guiding the surgical extension in cases confirmed as malignant by FNA; however, only 33% accepted FS as a routine examination for the management of thyroid nodules. The influence of FS on surgical reintervention rate in nodular thyroid pathology was considered to be negligible by most studies, whereas 31 % of the authors thought that FS has a favorable benefit by decreasing the number of surgical re-interventions. In conclusion, the role of FS in thyroid pathology evolved from a mandatory component for thyroid surgery to an optional examination after a pre-operative FNA cytology. The accuracy of FS seems to provide no sufficient additional benefit and most experts support its use only in the presence of equivocal or suspicious cytological features, for guiding the surgical extension in cases confirmed as malignant by FNA and for the identification of other potentially confusing intraoperative findings.

Unraveling the intrafamilial correlations and heritability of tumor types in MEN1: a Groupe d'étude des Tumeurs Endocrines study

BACKGROUND

MEN1, which is secondary to the mutation of the MEN1 gene, is a rare autosomal-dominant disease that predisposes mutation carriers to endocrine tumors. Most studies demonstrated the absence of direct genotype-phenotype correlations. The existence of a higher risk of death in the Groupe d'étude des Tumeurs Endocrines-cohort associated with a mutation in the JunD interacting domain suggests heterogeneity across families in disease expressivity. This study aims to assess the existence of modifying genetic factors by estimating the intrafamilial correlations and heritability of the six main tumor types in MEN1.

METHODS

The study included 797 patients from 265 kindred and studied seven phenotypic criteria: parathyroid and pancreatic neuroendocrine tumors (NETs) and pituitary, adrenal, bronchial, and thymic (thNET) tumors and the presence of metastasis. Intrafamilial correlations and heritability estimates were calculated from family tree data using specific validated statistical analysis software.

RESULTS

Intrafamilial correlations were significant and decreased along parental degrees distance for pituitary, adrenal and thNETs. The heritability of these three tumor types was consistently strong and significant with 64% (s.e.m.=0.13; P<0.001) for pituitary tumor, 65% (s.e.m.=0.21; P<0.001) for adrenal tumors, and 97% (s.e.m.=0.41; P=0.006) for thNETs.

CONCLUSION

The present study shows the existence of modifying genetic factors for thymus, adrenal, and pituitary MEN1 tumor types. The identification of at-risk subgroups of individuals within cohorts is the first step toward personalization of care. Next generation sequencing on this subset of tumors will help identify the molecular basis of MEN1 variable genetic expressivity.

[Light pollution. A connection between ecology and health]

Light pollution is defined as the abnormal and disturbing nocturnal presence of light, its adverse consequences on flora, fauna, and, ecosystems, and its suspected or proven effects on human health. Light pollution is a quite recent and increasing phenomenon within our society; it leads to a major environmental damage not only on wildlife, but also on human health (cancers, obesity, fatigue, depression...). The solutions to this problem are however simple, efficient and, de facto, inexpensive because they involve a substantial energy saving.

[Old phenotype and new genotypes. Pituitary adenomas]

Gigantism and acromegaly, usually caused by a pituitary adenoma linked inappropriate secretion of growth hormone (GH), are generally considered as very rare diseases, even if, according to some authors, their cumulative prevalence is about 1/5000. Starting from the historical case of a giant from Liège we shall describe the different types of GH pituitary adenomas and their pathophysiology. We shall particularly discuss rare forms of inherited GH secreting pituitary adenomas like the FIPA (familial inherited isolated pituitary adenomas) and the X-LAG (X linked acrogigantism), both described for the first time in Liège, in 2000 and 2014, respectively.

Abstract 4731: Targeting super-enhancer induced gene expression with the novel BRD4 inhibitor OTX015 in preclinical models of MYCN-amplified neuroblastoma

Bromodomain-containing protein 4 (BRD4) functions as an epigenetic reader and binds to promoter super-enhancer regions driving oncogenes such as MYC. Neuroblastomas (NB) harboring MYCN amplifications are highly lethal tumors often resistant to standard chemotherapy. OTX015 is a novel BRD2/3/4 inhibitor currently in clinical Phase Ib studies in hematologic malignancies and solid tumors. We have previously reported that OTX015 displayed in vitro and in vivo antitumor effects, together with MYCN transcription attenuation in NB models (Henssen et al; AACR 2014). Here, we investigated OTX015 targeting of super-enhancer regulated genes in MYCN-amplified NB in vitro and in vivo models. Protein-DNA interactions were analyzed using ChipSeq in IMR 5 cells. We identified super-enhancers associated with a variety of genes of known importance in NB, including MYCN, as well as some previously undescribed genes. OTX015 inhibited cell proliferation in Chp-212, Chp-134, Gimen, IMR-32, NB69, SK-N-AS, SK-N-BE, and SK-N-BE2 NB cell lines after 72 h exposure. OTX015 reduced tumor burden in IMR 5 xenograft mice and in a genetically engineered model of MYCN-amplified NB LSL MYCN;Dbh-iCre, when administered by oral gavage at a dose of 25 mg/kg daily for 3 weeks. Antitumoral effects of OTX015 were coupled with decreased binding of BRD4 to chromatin and subsequent global transcriptional changes. Moreover, OTX015 exposure led to significant transcriptional downregulation of genes associated with super-enhancers, supporting the notion that BRD4 preferentially acts at these chromatin sites. Interestingly, BRD inhibition not only attenuated MYCN transcription but most significantly affected MYCN-regulated transcriptional programs. Ectopic expression of MYCN was not able to abrogate the antitumoral effects of BRD4 inhibition, indicating direct involvement of MYCN in super-enhancer regulated gene expression and possibly explaining the increased susceptibility of MYCN-amplified NB to OTX015 inhibition. We describe here for the first time that BRD inhibition by OTX015 selectively and preferentially targets global super-enhancer induced transcription in MYCN-driven NB. These new insights will serve as a rationale for a clinical trial in pediatric MYCN-amplified NB patients with OTX015.

Citation Format: Anton Henssen, Kristina Althoff, Richard Koche, Andrea Odersky, Anneleen Beckers, Frank Speleman, Simon Schäfers, Katleen De Preter, Alexandra Florin, Lukas Heukamp, Annika Spruessel, Kathy Astrahanseff, Natalie Sadowski, Alexander Schramm, Angelika Eggert, Lucile Astorgues-Xerri, Eugenia Riveiro, Esteban Cvitkovic, Johannes H. Schulte. Targeting super-enhancer induced gene expression with the novel BRD4 inhibitor OTX015 in preclinical models of MYCN-amplified neuroblastoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4731. doi:10.1158/1538-7445.AM2015-4731

[Alpha interferon induced hyperthyroidism: a case report and review of the literature]

Treatment with alpha interferon in hepatitis C triggers a thyroid autoimmunity in a variable percentage of cases (2-8%). This complication raises some questions about its screening, the possibility to continue anti-viral therapy and thyroid treatment. Alpha interferon has an immunomodulatory effect on the thyroid, but also an inhibitory effect on thyroid hormone synthesis. This explains the occurrence of cases of thyroid dysfunction, which often remain undetected because of their latency. Factors predicting thyroid dysfunction with interferon use are: female sex, history of thyroid disease and previous autoimmunity. Several clinical aspects are encountered including hypothyroidism (the most frequent depending on the series) and hyperthyroidism related to Graves' disease. For their detection, a cooperation between general practionners, gastroenterologists and endocrinologists is mandatory thyroid function tests are requested before, during and after treatment,with alpha interferon. Therapeutic aspects of thyroid disorders range from simple monitoring to symptomatic treatment, such as thyroxine prescription in the presence of hypothyroidism. Antithyroid drugs radioactive iodine or thyroid surgery are used in cases of severe or persistent Graves' disease induced by alpha interferon.

MYCN-driven regulatory mechanisms controlling LIN28B in neuroblastoma

LIN28B has been identified as an oncogene in various tumor entities, including neuroblastoma, a childhood cancer that originates from neural crest-derived cells, and is characterized by amplification of the MYCN oncogene. Recently, elevated LIN28B expression levels were shown to contribute to neuroblastoma tumorigenesis via let-7 dependent de-repression of MYCN. However, additional insight in the regulation of LIN28B in neuroblastoma is lacking. Therefore, we have performed a comprehensive analysis of the regulation of LIN28B in neuroblastoma, with a specific focus on the contribution of miRNAs. We show that MYCN regulates LIN28B expression in neuroblastoma tumors via two distinct parallel mechanisms. First, through an unbiased LIN28B-3'UTR reporter screen, we found that miR-26a-5p and miR-26b-5p regulate LIN28B expression. Next, we demonstrated that MYCN indirectly affects the expression of miR-26a-5p, and hence regulates LIN28B, therefore establishing an MYCN-miR-26a-5p-LIN28B regulatory axis. Second, we provide evidence that MYCN regulates LIN28B expression via interaction with the LIN28B promoter, establishing a direct MYCN-LIN28B regulatory axis. We believe that these findings mark LIN28B as an important effector of the MYCN oncogenic phenotype and underline the importance of MYCN-regulated miRNAs in establishing the MYCN-driven oncogenic process.

Upregulation of MAPK Negative Feedback Regulators and RET in Mutant ALK Neuroblastoma: Implications for Targeted Treatment

PURPOSE

Activating ALK mutations are present in almost 10% of primary neuroblastomas and mark patients for treatment with small-molecule ALK inhibitors in clinical trials. However, recent studies have shown that multiple mechanisms drive resistance to these molecular therapies. We anticipated that detailed mapping of the oncogenic ALK-driven signaling in neuroblastoma can aid to identify potential fragile nodes as additional targets for combination therapies.

EXPERIMENTAL DESIGN

To achieve this goal, transcriptome profiling was performed in neuroblastoma cell lines with the ALK(F1174L) or ALK(R1275Q) hotspot mutations, ALK amplification, or wild-type ALK following pharmacologic inhibition of ALK using four different compounds. Next, we performed cross-species genomic analyses to identify commonly transcriptionally perturbed genes in MYCN/ALK(F1174L) double transgenic versus MYCN transgenic mouse tumors as compared with the mutant ALK-driven transcriptome in human neuroblastomas.

RESULTS

A 77-gene ALK signature was established and successfully validated in primary neuroblastoma samples, in a neuroblastoma cell line with ALK(F1174L) and ALK(R1275Q) regulable overexpression constructs and in other ALKomas. In addition to the previously established PI3K/AKT/mTOR, MAPK/ERK, and MYC/MYCN signaling branches, we identified that mutant ALK drives a strong upregulation of MAPK negative feedback regulators and upregulates RET and RET-driven sympathetic neuronal markers of the cholinergic lineage.

CONCLUSIONS

We provide important novel insights into the transcriptional consequences and the complexity of mutant ALK signaling in this aggressive pediatric tumor. The negative feedback loop of MAPK pathway inhibitors may affect novel ALK inhibition therapies, whereas mutant ALK induced RET signaling can offer novel opportunities for testing ALK-RET oriented molecular combination therapies.

[Amiodarone and the thyroid]

Amiodarone is an antiarrhythmic agent among the I most powerful and the most frequently used for the control of recurrent ventricular tachycardia and the secondary prevention of recurrent atrial fibrillation. Its use is not without risk. Although highly effective, it may induce various, sometimes severe, side effects, particularly at the thyroid level.In patients receiving amiodarone, one can encounter biological changes without clinical repercussion. Some may present a true thyroid disease, either hyper- or hypothyroidism. In this literature review, we will see how to prevent, diagnose, and treat these complications,if required.