INA03, a potent transferrin-competitive antibody-drug conjugate against CD71, for a safer acute leukemia treatment.

Innovative strategies to enhance efficacy and overcome drug resistance in hematologic cancers such as antibody-drug conjugates (ADCs) have shifted the paradigm of conventional care by delivering promising outcomes in cancer therapies with a significant reduction in the risk of relapse. The transferrin receptor 1, CD71, known to be overexpressed in malignant cells, is considered a potent anti-tumoral target. Therefore, we have developed an anti-CD71 ADC, INA03, a humanized antibody conjugated to the monomethyl auristatin E (MMAE) through a 3-arylpropiolonitrile-valine-citruline linker. In this study, we investigated both potency and safety of INA03, in competition with transferrin (Tf), the CD71's natural ligand, as a novel strategy to specifically target highly proliferative cells. The high expression of CD71 was confirmed on different leukemic cell lines, allowing INA03 to bind efficiently. Subsequently, INA03 rapidly internalizes into lysosomal compartments, where its cytotoxic drug is released following cathepsin-B cleavage. Downregulating CD71 expression using shRNA highlighted that INA03-induced cell death was dependent on CD71 density at the cell surface. INA03 intravenous treatment in acute leukemia mouse models significantly reduced tumor burden, increased mice survival and showed no residual disease compared to conventional chemotherapies. Since INA03 competes with the human Tf, a double knock-in (hCD71/hTf) competent mouse model was generated to mimic human pharmacokinetics and pharmacodynamics. INA03 administration in hCD71/hTf mice did not reveal, even at high doses, any improper toxicities. Hence, these data demonstrate promising pre-clinical efficacy and safety of INA03 and support its development as a novel acute leukemia treatment.

Immune sensing of food allergens promotes avoidance behaviour.

In addition to its canonical function of protection from pathogens, the immune system can also alter behaviour1,2. The scope and mechanisms of behavioural modifications by the immune system are not yet well understood. Here, using mouse models of food allergy, we show that allergic sensitization drives antigen-specific avoidance behaviour. Allergen ingestion activates brain areas involved in the response to aversive stimuli, including the nucleus of tractus solitarius, parabrachial nucleus and central amygdala. Allergen avoidance requires immunoglobulin E (IgE) antibodies and mast cells but precedes the development of gut allergic inflammation. The ability of allergen-specific IgE and mast cells to promote avoidance requires cysteinyl leukotrienes and growth and differentiation factor 15. Finally, a comparison of C57BL/6 and BALB/c mouse strains revealed a strong effect of the genetic background on the avoidance behaviour. These findings thus point to antigen-specific behavioural modifications that probably evolved to promote niche selection to avoid unfavourable environments.

Overexpression of GILZ in macrophages limits systemic inflammation while increasing bacterial clearance in sepsis in mice.

Studies support the beneficial effects of glucocorticoids (GCs) during septic shock, steering research toward the potential role of GC-induced proteins in controlling excessive inflammatory responses. GILZ is a glucocorticoid-induced protein involved in the anti-inflammatory effects of GCs. We investigated whether the overexpression of GILZ specifically limited to monocytes and macrophages (M/M) alone could control inflammation, thus improving the outcome of septic shock in animal models. We also monitored the expression of GILZ in M/M from septic mice and septic-shock patients. M/M from patients and septic mice displayed significantly lower expression of GILZ than those isolated from controls. Furthermore, transgenic mice (Tg-mice) experiencing sepsis, with increased expression of GILZ restricted to M/M, showed lower frequencies of inflammatory monocytes than their littermates and lower plasma levels of inflammatory cytokines. Tg-mice also had lower blood bacterial counts. We further established that the upregulation of GILZ in M/M enhanced their phagocytic capacity in in vivo assays. The increase of GILZ in M/M was also sufficient to improve the survival rates of septic mice. These results provide evidence for a central role of both GILZ and M/M in the pathophysiology of septic shock and a possible clue for the modulation of inflammation in this disease.

Hemogenic Endothelial Fate Mapping Reveals Dual Developmental Origin of Mast Cells.

Hematopoiesis occurs in distinct waves. "Definitive" hematopoietic stem cells (HSCs) with the potential for all blood lineages emerge in the aorta-gonado-mesonephros, while "primitive" progenitors, whose potential is thought to be limited to erythrocytes, megakaryocytes, and macrophages, arise earlier in the yolk sac (YS). Here, we questioned whether other YS lineages exist that have not been identified, partially owing to limitations of current lineage tracing models. We established the use of Cdh5-CreERT2 for hematopoietic fate mapping, which revealed the YS origin of mast cells (MCs). YS-derived MCs were replaced by definitive MCs, which maintained themselves independently from the bone marrow in the adult. Replacement occurred with tissue-specific kinetics. MCs in the embryonic skin, but not other organs, remained largely YS derived prenatally and were phenotypically and transcriptomically distinct from definite adult MCs. We conclude that within myeloid lineages, dual hematopoietic origin is shared between macrophages and MCs.

Lyn and Fyn function as molecular switches that control immunoreceptors to direct homeostasis or inflammation.

Immunoreceptors can transduce either inhibitory or activatory signals depending on ligand avidity and phosphorylation status, which is modulated by the protein kinases Lyn and Fyn. Here we show that Lyn and Fyn control immune receptor signaling status. SHP-1 tyrosine 536 phosphorylation by Lyn activates the phosphatase promoting inhibitory signaling through the immunoreceptor. By contrast, Fyn-dependent phosphorylation of SHP-1 serine 591 inactivates the phosphatase, enabling activatory immunoreceptor signaling. These SHP-1 signatures are relevant in vivo, as Lyn deficiency exacerbates nephritis and arthritis in mice, whereas Fyn deficiency is protective. Similarly, Fyn-activating signature is detected in patients with lupus nephritis, underlining the importance of this Lyn-Fyn balance. These data show how receptors discriminate negative from positive signals that respectively result in homeostatic or inflammatory conditions.Src-family kinases Fyn and Lyn are signaling components downstream of ITAM-bearing antigen receptors. Here the authors show that by phosphorylating SHP-1 at different residues, Lyn and Fyn can have opposing regulatory effects on ITAM receptors.

Mast cells regulate myofilament calcium sensitization and heart function after myocardial infarction.

Acute myocardial infarction (MI) is a severe ischemic disease responsible for heart failure and sudden death. Inflammatory cells orchestrate postischemic cardiac remodeling after MI. Studies using mice with defective mast/stem cell growth factor receptor c-Kit have suggested key roles for mast cells (MCs) in postischemic cardiac remodeling. Because c-Kit mutations affect multiple cell types of both immune and nonimmune origin, we addressed the impact of MCs on cardiac function after MI, using the c-Kit-independent MC-deficient (Cpa3(Cre/+)) mice. In response to MI, MC progenitors originated primarily from white adipose tissue, infiltrated the heart, and differentiated into mature MCs. MC deficiency led to reduced postischemic cardiac function and depressed cardiomyocyte contractility caused by myofilament Ca(2+) desensitization. This effect correlated with increased protein kinase A (PKA) activity and hyperphosphorylation of its targets, troponin I and myosin-binding protein C. MC-specific tryptase was identified to regulate PKA activity in cardiomyocytes via protease-activated receptor 2 proteolysis. This work reveals a novel function for cardiac MCs modulating cardiomyocyte contractility via alteration of PKA-regulated force-Ca(2+) interactions in response to MI. Identification of this MC-cardiomyocyte cross-talk provides new insights on the cellular and molecular mechanisms regulating the cardiac contractile machinery and a novel platform for therapeutically addressable regulators.

Ocular inflammation induces trigeminal pain, peripheral and central neuroinflammatory mechanisms.

Ocular surface diseases are among the most frequent ocular pathologies, with prevalence ranging from 20% of the general population. In addition, ocular pain following corneal injury is frequently observed in clinic. The aim of the study was to characterize the peripheral and central neuroinflammatory process in the trigeminal pathways in response to cornea alteration induced by chronic topical instillations of 0.2% benzalkonium chloride (BAC) in male C57BL/6J mice. In vitro BAC induced neurotoxicity and increases neuronal (FOS, ATF3) and pro-inflammatory (IL-6) markers in primary mouse trigeminal ganglion culture. BAC-treated mice exhibited 7days after the treatment reduced aqueous tear production and increased inflammatory cell infiltration in the cornea. Hypertonic saline-evoked eye wipe behavior was enhanced in BAC-treated animals that exhibited increased FOS, ATF3 and Iba1 immunoreactivity in the trigeminal ganglion. Ocular inflammation is associated with a significant increase in IL-6 and TNF-α mRNA expression in the trigeminal ganglion. We reported a strong increase in FOS and Iba1 positive cells in particular in the sensory trigeminal complex at the ipsilateral interpolaris/caudalis (Vi/Vc) transition and Vc/upper cervical cord (Vc/C1) regions. In addition, activated microglial cells were tightly wrapped around activated FOS neurons in both regions and phosphorylated p38 mitogen-activated protein kinase was markedly enhanced specifically in microglial cells during ocular inflammation. Similar data were obtained in the facial motor nucleus. These neuroanatomical data correlated with the increase in mRNA expression of pro-inflammatory (TNF-α, IL-6, CCL2) and neuronal (FOS and ATF3) markers. Interestingly, the suppression of corneal inflammation 10days following the end of BAC treatment resulted in a marked attenuation of peripheral and central changes observed in pathological conditions. This study provides the first demonstration that corneal inflammation induces activation of neurons and microglial p38 MAPK pathway within sensory trigeminal complex. These results suggest that this altered activity in intracellular signaling caused by ocular inflammation might play a priming role in the central sensitization of ocular related brainstem circuits, which represents a significant factor in ocular pain development.

CD47 agonist peptides induce programmed cell death in refractory chronic lymphocytic leukemia B cells via PLCγ1 activation: evidence from mice and humans.

BACKGROUND: Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia, is characterized by the accumulation of abnormal CD5+ B lymphocytes, which results in a progressive failure of the immune system. Despite intense research efforts, drug resistance remains a major cause of treatment failure in CLL, particularly in patients with dysfunctional TP53. The objective of our work was to identify potential approaches that might overcome CLL drug refractoriness by examining the pro-apoptotic potential of targeting the cell surface receptor CD47 with serum-stable agonist peptides. METHODS AND FINDINGS: In peripheral blood samples collected from 80 patients with CLL with positive and adverse prognostic features, we performed in vitro genetic and molecular analyses that demonstrate that the targeting of CD47 with peptides derived from the C-terminal domain of thrombospondin-1 efficiently kills the malignant CLL B cells, including those from high-risk individuals with a dysfunctional TP53 gene, while sparing the normal T and B lymphocytes from the CLL patients. Further studies reveal that the differential response of normal B lymphocytes, collected from 20 healthy donors, and leukemic B cells to CD47 peptide targeting results from the sustained activation in CLL B cells of phospholipase C gamma-1 (PLCγ1), a protein that is significantly over-expressed in CLL. Once phosphorylated at tyrosine 783, PLCγ1 enables a Ca2+-mediated, caspase-independent programmed cell death (PCD) pathway that is not down-modulated by the lymphocyte microenvironment. Accordingly, down-regulation of PLCγ1 or pharmacological inhibition of PLCγ1 phosphorylation abolishes CD47-mediated killing. Additionally, in a CLL-xenograft model developed in NOD/scid gamma mice, we demonstrate that the injection of CD47 agonist peptides reduces tumor burden without inducing anemia or toxicity in blood, liver, or kidney. The limitations of our study are mainly linked to the affinity of the peptides targeting CD47, which might be improved to reach the standard requirements in drug development, and the lack of a CLL animal model that fully mimics the human disease. CONCLUSIONS: Our work provides substantial progress in (i) the development of serum-stable CD47 agonist peptides that are highly effective at inducing PCD in CLL, (ii) the understanding of the molecular events regulating a novel PCD pathway that overcomes CLL apoptotic avoidance, (iii) the identification of PLCγ1 as an over-expressed protein in CLL B cells, and (iv) the description of a novel peptide-based strategy against CLL.

Mast cells in renal inflammation and fibrosis: lessons learnt from animal studies.

Mast cells are hematopoietic cells involved in inflammation and immunity and have been recognized also as important effector cells in kidney inflammation. In humans, only a few mast cells reside in kidneys constitutively but in progressive renal diseases their numbers increase substantially representing an essential part of the interstitial infiltrate of inflammatory cells. Recent data obtained in experimental animal models have emphasized a complex role of these cells and the mediators they release as they have been shown both to promote, but also to protect from disease and fibrosis development. Sometimes conflicting results have been reported in similar models suggesting a very narrow window between these activities depending on the pathophysiological context. Interestingly in mice, mast cell or mast cell mediator specific actions became also apparent in the absence of significant mast cell kidney infiltration supporting systemic or regional actions via draining lymph nodes or kidney capsules. Many of their activities rely on the capacity of mast cells to release, in a timely controlled manner, a wide range of inflammatory mediators, which can promote anti-inflammatory actions and repair activities that contribute to healing, but in some circumstances or in case of inappropriate regulation may also promote kidney disease.

Mast cells aggravate sepsis by inhibiting peritoneal macrophage phagocytosis.

Controlling the overwhelming inflammatory reaction associated with polymicrobial sepsis remains a prevalent clinical challenge with few treatment options. In septic peritonitis, blood neutrophils and monocytes are rapidly recruited into the peritoneal cavity to control infection, but the role of resident sentinel cells during the early phase of infection is less clear. In particular, the influence of mast cells on other tissue-resident cells remains poorly understood. Here, we developed a mouse model that allows both visualization and conditional ablation of mast cells and basophils to investigate the role of mast cells in severe septic peritonitis. Specific depletion of mast cells led to increased survival rates in mice with acute sepsis. Furthermore, we determined that mast cells impair the phagocytic action of resident macrophages, thereby allowing local and systemic bacterial proliferation. Mast cells did not influence local recruitment of neutrophils and monocytes or the release of inflammatory cytokines. Phagocytosis inhibition by mast cells involved their ability to release prestored IL-4 within 15 minutes after bacterial encounter, and treatment with an IL-4-neutralizing antibody prevented this inhibitory effect and improved survival of septic mice. Our study uncovers a local crosstalk between mast cells and macrophages during the early phase of sepsis development that aggravates the outcome of severe bacterial infection.

Shifting FcγRIIA-ITAM from activation to inhibitory configuration ameliorates arthritis.

Rheumatoid arthritis-associated (RA-associated) inflammation is mediated through the interaction between RA IgG immune complexes and IgG Fc receptors on immune cells. Polymorphisms within the gene encoding the human IgG Fc receptor IIA (hFcγRIIA) are associated with an increased risk of developing RA. Within the hFcγRIIA intracytoplasmic domain, there are 2 conserved tyrosine residues arranged in a noncanonical immunoreceptor tyrosine-based activation motif (ITAM). Here, we reveal that inhibitory engagement of the hFcγRIIA ITAM either with anti-hFcγRII F(ab')2 fragments or intravenous hIgG (IVIg) ameliorates RA-associated inflammation, and this effect was characteristic of previously described inhibitory ITAM (ITAMi) signaling for hFcαRI and hFcγRIIIA, but only involves a single tyrosine. In hFcγRIIA-expressing mice, arthritis induction was inhibited following hFcγRIIA engagement. Moreover, hFcγRIIA ITAMi-signaling reduced ROS and inflammatory cytokine production through inhibition of guanine nucleotide exchange factor VAV-1 and IL-1 receptor-associated kinase 1 (IRAK-1), respectively. ITAMi signaling was mediated by tyrosine 304 (Y304) within the hFcγRIIA ITAM, which was required for recruitment of tyrosine kinase SYK and tyrosine phosphatase SHP-1. Anti-hFcγRII F(ab')2 treatment of inflammatory synovial cells from RA patients inhibited ROS production through induction of ITAMi signaling. These data suggest that shifting constitutive hFcγRIIA-mediated activation to ITAMi signaling could ameliorate RA-associated inflammation.

Substitution p.A350V in Na⁺/Mg²âº exchanger SLC41A1, potentially associated with Parkinson's disease, is a gain-of-function mutation.

Parkinson's disease (PD) is a complex multifactorial ailment predetermined by the interplay of various environmental and genetic factors. Systemic and intracellular magnesium (Mg) deficiency has long been suspected to contribute to the development and progress of PD and other neurodegenerative diseases. However, the molecular background is unknown. Interestingly, gene SLC41A1 located in the novel PD locus PARK16 has recently been identified as being a Na⁺/Mg²âº exchanger (NME, Mg²âº efflux system), a key component of cellular magnesium homeostasis. Here, we demonstrate that the substitution p.A350V potentially associated with PD is a gain-of-function mutation that enhances a core function of SLC41A1, namely Na⁺-dependent Mg²âº efflux by 69±10% under our experimental conditions (10-minute incubation in high-Na⁺ (145 mM) and completely Mg²âº-free medium). The increased efflux capacity is accompanied by an insensitivity of mutant NME to cAMP stimulation suggesting disturbed hormonal regulation and leads to a reduced proliferation rate in p.A350V compared with wt cells. We hypothesize that enhanced Mg²âº-efflux conducted by SLC41A1 variant p.A350V might result, in the long-term, in chronic intracellular Mg²âº-deficiency, a condition that is found in various brain regions of PD patients and that exacerbates processes triggering neuronal damage.

Adenosine receptor antagonists including caffeine alter fetal brain development in mice.

Consumption of certain substances during pregnancy can interfere with brain development, leading to deleterious long-term neurological and cognitive impairments in offspring. To test whether modulators of adenosine receptors affect neural development, we exposed mouse dams to a subtype-selective adenosine type 2A receptor (A2AR) antagonist or to caffeine, a naturally occurring adenosine receptor antagonist, during pregnancy and lactation. We observed delayed migration and insertion of γ-aminobutyric acid (GABA) neurons into the hippocampal circuitry during the first postnatal week in offspring of dams treated with the A2AR antagonist or caffeine. This was associated with increased neuronal network excitability and increased susceptibility to seizures in response to a seizure-inducing agent. Adult offspring of mouse dams exposed to A2AR antagonists during pregnancy and lactation displayed loss of hippocampal GABA neurons and some cognitive deficits. These results demonstrate that exposure to A2AR antagonists including caffeine during pregnancy and lactation in rodents may have adverse effects on the neural development of their offspring.

Silencing mutated ß-catenin inhibits cell proliferation and stimulates apoptosis in the adrenocortical cancer cell line H295R.

CONTEXT: Adrenocortical carcinoma (ACC) is a rare and highly aggressive endocrine neoplasm, with limited therapeutic options. Activating ß-catenin somatic mutations are found in ACC and have been associated with a poor clinical outcome. In fact, activation of the Wnt/ß-catenin signaling pathway seems to play a major role in ACC aggressiveness, and might, thus, represent a promising therapeutic target. OBJECTIVE: Similar to patient tumor specimen the H295 cell line derived from an ACC harbors a natural activating ß-catenin mutation. We herein assess the in vitro and in vivo effect of ß-catenin inactivation using a doxycyclin (dox) inducible shRNA plasmid in H295R adrenocortical cancer cells line (clone named shß). RESULTS: Following dox treatment a profound reduction in ß-catenin expression was detectable in shß clones in comparison to control clones (Ctr). Accordingly, we observed a decrease in Wnt/ßcatenin-dependent luciferase reporter activity as well as a decreased expression of AXIN2 representing an endogenous ß-catenin target gene. Concomitantly, ß-catenin silencing resulted in a decreased cell proliferation, cell cycle alterations with cell accumulation in the G1 phase and increased apoptosis in vitro. In vivo, on established tumor xenografts in athymic nude mice, 9 days of ß-catenin silencing resulted in a significant reduction of CTNNB1 and AXIN2 expression. Moreover, continous ß-catenin silencing, starting 3 days after tumor cell inoculation, was associated with a complete absence of tumor growth in the shß group while tumors were present in all animals of the control group. CONCLUSION: In summary, these experiments provide evidences that Wnt/ß-catenin pathway inhibition in ACC is a promising therapeutic target.

The TRPM4 channel controls monocyte and macrophage, but not neutrophil, function for survival in sepsis.

A favorable outcome following acute bacterial infection depends on the ability of phagocytic cells to be recruited and properly activated within injured tissues. Calcium (Ca(2+)) is a ubiquitous second messenger implicated in the functions of many cells, but the mechanisms involved in the regulation of Ca(2+) mobilization in hematopoietic cells are largely unknown. The monovalent cation channel transient receptor potential melastatin (TRPM) 4 is involved in the control of Ca(2+) signaling in some hematopoietic cell types, but the role of this channel in phagocytes and its relevance in the control of inflammation remain unexplored. In this study, we report that the ablation of the Trpm4 gene dramatically increased mouse mortality in a model of sepsis induced by cecal ligation and puncture. The lack of the TRPM4 channel affected macrophage population within bacteria-infected peritoneal cavities and increased the systemic level of Ly6C(+) monocytes and proinflammatory cytokine production. Impaired Ca(2+) mobilization in Trpm4(-/-) macrophages downregulated the AKT signaling pathway and the subsequent phagocytic activity, resulting in bacterial overgrowth and translocation to the bloodstream. In contrast, no alteration in the distribution, function, or Ca(2+) mobilization of Trpm4(-/-) neutrophils was observed, indicating that the mechanism controlling Ca(2+) signaling differs among phagocytes. Our results thus show that the tight control of Ca(2+) influx by the TRPM4 channel is critical for the proper functioning of monocytes/macrophages and the efficiency of the subsequent response to infection.

Inhibitory ITAM signaling traps activating receptors with the phosphatase SHP-1 to form polarized "inhibisome" clusters.

The ability of immunoreceptor tyrosine-based activation motif (ITAM)-bearing receptors to inhibit, rather than activate, signaling by other receptors is a regulatory mechanism of immune homeostasis. However, it remains unclear how inhibitory ITAM (ITAMi) receptor signaling and Src homology 2 (SH2) domain-containing phosphatase-1 (SHP-1), which is recruited to ITAMs, target multiple heterologous activating responses without coaggregating with the associated activating receptors. We found that ITAMi signaling triggered by the binding of monomeric ligands to the type I immunoglobulin A (IgA) Fc receptor (FcαRI) induced its dynamic cosegregation with heterologous activating receptors, signaling effectors, and the inhibitory phosphatase SHP-1 into polarized intracellular clusters that we call "inhibisomes." Formation of inhibisomes was preceded by the recruitment of FcαRI and SHP-1 into lipid rafts. Cosegregation required the depolymerization of actin, which depended on SHP-1, and inhibisome formation was abolished by knockdown of SHP-1 and by actin-depolymerizing drugs. Thus, SHP-1- and actin depolymerization-dependent spatiotemporal compartmentalization of ITAMi-containing receptors into lipid rafts, regions associated with intracellular signaling, represents a key event in the integration of ITAMi-mediated inhibitory signals.

ß-catenin activation is associated with specific clinical and pathologic characteristics and a poor outcome in adrenocortical carcinoma.

PURPOSE: Activation of the Wnt/ß-catenin signaling pathway is frequent in adrenocortical carcinoma (ACC) and might be associated with a more aggressive phenotype. The objective of this study was to assess the prognostic value of ß-catenin immunohistochemistry and CTNNB1 (ß-catenin gene)/APC (adenomatous polyposis coli gene) mutations in patients with resected primary ACC. EXPERIMENTAL DESIGN: In 79 patients with resected primary ACC from a French cohort (Cochin-COMETE), ß-catenin expression was assessed on tumor specimens by immunohistochemistry. For patients with available DNA (n = 49), CTNNB1, and APC hotspot (mutation cluster region), were sequenced. Association between these results and the clinicopathologic characteristics of the ACC and overall and disease-free survival were studied. Results were confirmed on a tissue microarray from an independent multicentric cohort of 92 ACC from Germany (German-ENSAT cohort). RESULTS: In the Cochin-COMETE cohort, the presence of a ß-catenin nuclear staining was significantly associated with a higher ENSAT tumor stage (i.e., stages III and IV), higher Weiss score, more frequent necrosis, mitoses, and CTNNB1/APC mutations. ß-Catenin nuclear staining and the presence of CTNNB1/APC mutations were both associated with decreased overall and disease-free survival, and were independent predictive factors of survival in multivariate analysis. The same results were observed in the German-ENSAT cohort. CONCLUSIONS: Wnt/ß-catenin activation, confirmed by the presence of ß-catenin nuclear staining, is an independent prognostic factor of overall and disease-free survival in patients with resected primary ACC.

Wnt/ß-catenin pathway activation in adrenocortical adenomas is frequently due to somatic CTNNB1-activating mutations, which are associated with larger and nonsecreting tumors: a study in cortisol-secreting and -nonsecreting tumors.

BACKGROUND: Abnormal ß-catenin immunohistochemistry and mutations of the ß-catenin gene (CTNNB1) have been reported in adrenocortical adenomas (ACAs), but the frequencies of these defects and the phenotype of such tumors have not been clearly determined. OBJECTIVE: The objective of the study was to describe the Wnt/ß-catenin pathway alterations in 100 ACAs and their association with clinicopathological characteristics. PATIENTS AND METHODS: One hundred consecutive ACAs (excluding Conn's adenomas) were studied clinically by ß-catenin immunohistochemistry and direct sequencing of CTNNB1. RESULTS: Thirty-five ACAs were nonsecreting adenomas (NSAs), 19 were subclinical cortisol secreting adenomas (SCSAs), and 46 were cortisol secreting adenomas (CSAs). Fifty-one tumors had abnormal cytoplasmic and/or nuclear ß-catenin immunohistochemical staining, indicating Wnt/ß-catenin pathway alteration. Thirty-six tumors showed CTNNB1 mutations, which all showed abnormal immunohistochemical ß-catenin accumulation. Among the 64 nonmutated tumors, only 15 (23%) showed cytoplasmic and/or nuclear ß-catenin staining (P < 0.0001). Tumors with CTNNB1 mutations were predominantly nonsecreting (61% NSAs, 22% SCSAs, 16% CSAs) whereas nonmutated tumors were predominantly secreting (20% NSAs, 17% SCSAs, 62% CSAs) (P < 0.0001). Mean tumor size and weight were, respectively, 4.2 cm (± 1.3) and 28.4 g (± 21.4) for tumors with CTNNB1 mutations vs. 3.4 cm (± 0.9) and 18.2 g (± 8.2) for nonmutated tumors (P < 0.01). CONCLUSIONS: Abnormal cytoplasmic and/or nuclear ß-catenin immunohistochemical staining occurs in about half of ACAs. This suggests the activation of the Wnt/ß-catenin pathway, which could be explained by activating mutations of CTNNB1 in 70% of the cases. CTNNB1 mutations are mainly observed in larger and nonsecreting ACAs, suggesting that the Wnt/ß-catenin pathway activation is associated with the development of less differentiated ACAs.

Transcriptome analysis reveals that p53 and {beta}-catenin alterations occur in a group of aggressive adrenocortical cancers.

Adrenocortical carcinoma (ACC) is a rare disease with an overall poor but heterogeneous prognosis. This heterogeneity could reflect different mechanisms of tumor development. Gene expression profiling by transcriptome analysis led to ACC being divided into two groups of tumors with very different outcomes. Somatic inactivating mutations of the tumor suppressor gene TP53 and activating mutations of the proto-oncogene ß-catenin (CTNNB1) are the most frequent mutations identified in ACC. This study investigates the correlation between p53 and ß-catenin alterations and the molecular classification of ACC by transcriptome analysis of 51 adult sporadic ACCs. All TP53 and CTNNB1 mutations seemed to be mutually exclusive and were observed only in the poor-outcome ACC group. Most of the abnormal p53 and ß-catenin immunostaining was also found in this group. Fifty-two percent of the poor-outcome ACC group had TP53 or CTNNB1 mutations and 60% had abnormal p53 or ß-catenin immunostaining. Unsupervised clustering transcriptome analysis of this poor-outcome group revealed three different subgroups, two of them being associated with p53 or ß-catenin alterations, respectively. Analysis of p53 and ß-catenin target gene expressions in each cluster confirmed a profound and anticipated effect on tumor biology, with distinct profiles logically associated with the respective pathway alterations. The third group had no p53 or ß-catenin alteration, suggesting other unidentified molecular defects. This study shows the important respective roles of p53 and ß-catenin in ACC development, delineating subgroups of ACC with different tumorigenesis and outcomes.

Inactivation of the APC gene is constant in adrenocortical tumors from patients with familial adenomatous polyposis but not frequent in sporadic adrenocortical cancers.

PURPOSE: In adrenocortical tumors (ACT), Wnt/ß-catenin pathway activation can be explained by ß-catenin somatic mutations only in a subset of tumors. ACT is observed in patients with familial adenomatous polyposis (FAP) with germline APC mutations, as well as in patients with Beckwith-Wiedemann syndrome with Wilms' tumors reported to have WTX somatic mutations. Both APC and WTX are involved in Wnt/ß-catenin pathway regulation and may play a role in ACT tumorigenesis. The aim of this study was to report if APC and WTX may be associated with FAP-associated and sporadic ACT. EXPERIMENTAL DESIGN: ACTs from patients with FAP and sporadic adrenocortical carcinomas (ACC) with abnormal ß-catenin localization on immunohistochemistry but no somatic ß-catenin mutations were studied. APC was analyzed by denaturing high-performance liquid chromatography followed by direct sequencing and by multiplex ligation-dependent probe amplification when allelic loss was suspected. WTX was studied by direct sequencing. RESULTS: Four ACTs were observed in three patients with FAP and were ACC, adrenocortical adenoma, and bilateral macronodular adrenocortical hyperplasia, all with abnormal ß-catenin localization. Biallelic inactivation of APC was strongly suggested by the simultaneous existence of somatic and germline alterations in all ACTs. In the 20 sporadic ACCs, a silent heterozygous somatic mutation as well as a rare heterozygous polymorphism in APC was found. No WTX mutations were observed. CONCLUSIONS: ACT should be considered a FAP tumor. Biallelic APC inactivation mediates activation of the Wnt/ß-catenin pathway in the ACTs of patients with FAP. In contrast, APC and WTX genetic alterations do not play a significant role in sporadic ACC.