ALK signaling primes the DNA damage response sensitizing ALK-driven neuroblastoma to therapeutic ATR inhibition.

High-risk neuroblastoma (NB) is a significant clinical challenge. MYCN and Anaplastic Lymphoma Kinase (ALK), which are often involved in high-risk NB, lead to increased replication stress in cancer cells, suggesting therapeutic strategies. We previously identified an ATR (ataxia telangiectasia and Rad3-related)/ALK inhibitor (ATRi/ALKi) combination as such a strategy in two independent genetically modified mouse NB models. Here, we identify an underlying molecular mechanism, in which ALK signaling leads to phosphorylation of ATR and CHK1, supporting an effective DNA damage response. The importance of ALK inhibition is supported by mouse data, in which ATRi monotreatment resulted in a robust initial response, but subsequent relapse, in contrast to a 14-d ALKi/ATRi combination treatment that resulted in a robust and sustained response. Finally, we show that the remarkable response to the 14-d combined ATR/ALK inhibition protocol reflects a robust differentiation response, reprogramming tumor cells to a neuronal/Schwann cell lineage identity. Our results identify an ability of ATR inhibition to promote NB differentiation and underscore the importance of further exploring combined ALK/ATR inhibition in NB, particularly in high-risk patient groups with oncogene-induced replication stress.

A radio-detected type Ia supernova with helium-rich circumstellar material.

Type Ia supernovae (SNe Ia) are thermonuclear explosions of degenerate white dwarf stars destabilized by mass accretion from a companion star1, but the nature of their progenitors remains poorly understood. A way to discriminate between progenitor systems is through radio observations; a non-degenerate companion star is expected to lose material through winds2 or binary interaction3 before explosion, and the supernova ejecta crashing into this nearby circumstellar material should result in radio synchrotron emission. However, despite extensive efforts, no type Ia supernova (SN Ia) has ever been detected at radio wavelengths, which suggests a clean environment and a companion star that is itself a degenerate white dwarf star4,5. Here we report on the study of SN 2020eyj, a SN Ia showing helium-rich circumstellar material, as demonstrated by its spectral features, infrared emission and, for the first time in a SN Ia to our knowledge, a radio counterpart. On the basis of our modelling, we conclude that the circumstellar material probably originates from a single-degenerate binary system in which a white dwarf accretes material from a helium donor star, an often proposed formation channel for SNe Ia (refs. 6,7). We describe how comprehensive radio follow-up of SN 2020eyj-like SNe Ia can improve the constraints on their progenitor systems.

RAL GTPases mediate EGFR-driven intestinal stem cell proliferation and tumourigenesis.

RAS-like (RAL) GTPases function in Wnt signalling-dependent intestinal stem cell proliferation and regeneration. Whether RAL proteins work as canonical RAS effectors in the intestine and the mechanisms of how they contribute to tumourigenesis remain unclear. Here, we show that RAL GTPases are necessary and sufficient to activate EGFR/MAPK signalling in the intestine, via induction of EGFR internalisation. Knocking down Drosophila RalA from intestinal stem and progenitor cells leads to increased levels of plasma membrane-associated EGFR and decreased MAPK pathway activation. Importantly, in addition to influencing stem cell proliferation during damage-induced intestinal regeneration, this role of RAL GTPases impacts on EGFR-dependent tumourigenic growth in the intestine and in human mammary epithelium. However, the effect of oncogenic RAS in the intestine is independent from RAL function. Altogether, our results reveal previously unrecognised cellular and molecular contexts where RAL GTPases become essential mediators of adult tissue homeostasis and malignant transformation.

Incidence of Appendiceal Malignancies in Sweden Between 1970 and 2012.

BACKGROUND: There is limited knowledge about the epidemiology of the major histological subtypes of appendiceal malignancy: adenocarcinoma and neuroendocrine neoplasm of the appendix (A-NEN). The aims of this national cohort study were to assess the prevalence, incidence and trends of appendiceal malignancies in Sweden. METHOD: All individuals who underwent appendicectomy and all diagnosed with appendiceal malignancy from 1970 to 2012 were identified from the National Patient Register and the Swedish Cancer Registry. Demographic data of the background population were obtained from Statistics Sweden. The incidence rate (IR) and the prevalence of appendiceal malignancy per performed appendicectomy were calculated. RESULTS: We identified 3774 patients with appendiceal malignancy. IR of A-NEN was 5.8/106 person-years with a peak of 8.4/106 at age 20-30 years, whereafter it plateaued at a somewhat lower level. IR for adenocarcinoma was 3.7/106 person-years, starting at a very low level among the youngest and increasing to 15.4/106 at age 80-89 years. The IR of adenocarcinoma increased from 2.6/106 in 1970-1979 to 5.4/106 in 2010-2012. The IR of A-NEN was stable during the study period. The prevalence per appendicectomy was low for both types of malignancies among the young but increased with age, most dramatically for adenocarcinoma. There was a trend during the study period towards more extensive surgery. CONCLUSION: Adenocarcinoma is most common and increasing in the elderly, whereas A-NEN affects all ages with a peak in young age. This peak probably reflects removal of occult A-NEN due to the higher appendicectomy frequency in the young.

RAL GTPases Drive Intestinal Stem Cell Function and Regeneration through Internalization of WNT Signalosomes.

Ral GTPases are RAS effector molecules and by implication a potential therapeutic target for RAS mutant cancer. However, very little is known about their roles in stem cells and tissue homeostasis. Using Drosophila, we identified expression of RalA in intestinal stem cells (ISCs) and progenitor cells of the fly midgut. RalA was required within ISCs for efficient regeneration downstream of Wnt signaling. Within the murine intestine, genetic deletion of either mammalian ortholog, Rala or Ralb, reduced ISC function and Lgr5 positivity, drove hypersensitivity to Wnt inhibition, and impaired tissue regeneration following damage. Ablation of both genes resulted in rapid crypt death. Mechanistically, RALA and RALB were required for efficient internalization of the Wnt receptor Frizzled-7. Together, we identify a conserved role for RAL GTPases in the promotion of optimal Wnt signaling, which defines ISC number and regenerative potential.

CXADR-Mediated Formation of an AKT Inhibitory Signalosome at Tight Junctions Controls Epithelial-Mesenchymal Plasticity in Breast Cancer.

Tight junctions (TJ) act as hubs for intracellular signaling pathways controlling epithelial cell fate and function. Deregulation of TJ is a hallmark of epithelial-mesenchymal transition (EMT), which contributes to carcinoma progression and metastasis. However, the signaling mechanisms linking TJ to the induction of EMT are not understood. Here, we identify a TJ-based signalosome, which controls AKT signaling and EMT in breast cancer. The coxsackie and adenovirus receptor (CXADR), a TJ protein with an essential yet uncharacterized role in organogenesis and tissue homeostasis, was identified as a key component of the signalosome. CXADR regulated the stability and function of the phosphatases and AKT inhibitors PTEN and PHLPP2. Loss of CXADR led to hyperactivation of AKT and sensitized cells to TGFß1-induced EMT. Conversely, restoration of CXADR stabilized PHLPP2 and PTEN, inhibited AKT, and promoted epithelial differentiation. Loss of CXADR in luminal A breast cancer correlated with loss of PHLPP2 and PTEN and poor prognosis. These results show that CXADR promotes the formation of an AKT-inhibitory signalosome at TJ and regulates epithelial-mesenchymal plasticity in breast cancer cells. Moreover, loss of CXADR might be used as a prognostic marker in luminal breast cancer. SIGNIFICANCE: The tight junction protein CXADR controls epithelial-mesenchymal plasticity in breast cancer by stabilizing the AKT regulators PTEN and PHLPP2.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/1/47/F1.large.jpg.

TGF-ß1-Induced Epithelial-Mesenchymal Transition Promotes Monocyte/Macrophage Properties in Breast Cancer Cells.

Breast cancer progression toward metastatic disease is linked to re-activation of epithelial-mesenchymal transition (EMT), a latent developmental process. Breast cancer cells undergoing EMT lose epithelial characteristics and gain the capacity to invade the surrounding tissue and migrate away from the primary tumor. However, less is known about the possible role of EMT in providing cancer cells with properties that allow them to traffic to distant sites. Given the fact that pro-metastatic cancer cells share a unique capacity with immune cells to traffic in-and-out of blood and lymphatic vessels we hypothesized that tumor cells undergoing EMT may acquire properties of immune cells. To study this, we performed gene-profiling analysis of mouse mammary EpRas tumor cells that had been allowed to adopt an EMT program after long-term treatment with TGF-ß1 for 2 weeks. As expected, EMT cells acquired traits of mesenchymal cell differentiation and migration. However, in addition, we found another cluster of induced genes, which was specifically enriched in monocyte-derived macrophages, mast cells, and myeloid dendritic cells, but less in other types of immune cells. Further studies revealed that this monocyte/macrophage gene cluster was enriched in human breast cancer cell lines displaying an EMT or a Basal B profile, and in human breast tumors with EMT and undifferentiated (ER-/PR-) characteristics. The results identify an EMT-induced monocyte/macrophage gene cluster, which may play a role in breast cancer cell dissemination and metastasis.

A Novel SMAD4 Mutation Causing Severe Juvenile Polyposis Syndrome with Protein Losing Enteropathy, Immunodeficiency, and Hereditary Haemorrhagic Telangiectasia.

Juvenile polyposis syndrome (JPS) is a rare genetic disorder characterized by juvenile polyps of the gastrointestinal tract. We present a new pathogenic mutation of the SMAD4 gene and illustrate the need for a multidisciplinary health care approach to facilitate the correct diagnosis. The patient, a 47-year-old Caucasian woman, was diagnosed with anaemia at the age of 12. During the following 30 years, she developed numerous gastrointestinal polyps. The patient underwent several operations, and suffered chronic abdominal pain, malnutrition, and multiple infections. Screening of the SMAD4 gene revealed a novel, disease-causing mutation. In 2012, the patient suffered hypoalbuminemia and a large polyp in the small bowel was found. Gamma globulin was given but the patient responded with fever and influenza-like symptoms and refused more treatment. The patient underwent surgery in 2014 and made an uneventful recovery. At follow-up two months later albumin was 38 g/L and IgG was 6.9 g/L. Accurate diagnosis is essential for medical care. For patients with complex symptomatology, often with rare diseases, this is best provided by multidisciplinary teams including representatives from clinical genetics. Patients with a SMAD4 mutation should be followed up both for JPS and haemorrhagic hereditary telangiectasia and may develop protein loosing enteropathy and immunodeficiency.

Littoral cell angioma in a patient with Crohn's disease.

Littoral cell angioma is a rare vascular tumor of the spleen. The pathogenesis is unknown but the lesion is associated with several malignancies and immunological disorders. The diagnosis requires histopathological examination. The malignant potential of this lesion is unknown, which is why splenectomy is recommend for all cases. Symptomatic cases generally suffer from hypersplenism and pyrexia. A previously healthy 20-year-old female was diagnosed with colonic Crohn's disease; as part of the work-up a magnetic resonance enterography was performed which showed multiple signal changes of the spleen. The patient reported chronic abdominal pain in the left upper quadrant, malaise, and fever. The unknown splenic lesions prompted a laparoscopic splenectomy; pathology revealed a littoral cell angioma. The abdominal pain and malaise remitted but the fever persisted one year despite adequate treatment of the patient's Crohn's disease. Littoral cell angioma is associated with immune-dysregulation including Crohn's disease with several reported cases. Signs and symptoms of hypersplenism and splenic lesions on imaging should raise suspicion of littoral cell angioma in patients with Crohn's disease. Magnetic resonance enterography to assess disease severity in Crohn's disease may provide an opportunity to study the prevalence and natural history of this rare splenic tumor.

Pinworm infestation mimicking crohns' disease.

We here report a case of a young man who presented to his general practitioner with diarrhea. Inflammatory bowel disease was suspected and a colonoscopy showed aphthous lesions suggestive of Crohns' disease but biopsies revealed eggs of Enterobius vermicularis. When treated for this parasite, his symptoms were alleviated and a followup colonoscopy revealed a normal colon and distal ileum. Enterobius vermicularis is the most common parasite worldwide and has been attributed with many different presentations and pathologies. It is therefore necessary to maintain vigilance, even in high-income countries, in order to diagnose patients with one of the many atypical presentations of pinworms.

Repeated cisplatin treatment can lead to a multiresistant tumor cell population with stem cell features and sensitivity to 3-bromopyruvate.

Cisplatin is used in treatment of several types of cancer, including epithelial ovarian carcinoma (EOC). In order to mimic clinical treatment and to investigate longterm effects of cisplatin in surviving cancer cells, two EOC cell lines were repeatedly treated with low doses. In the SKOV-3 cell line originating from malignant ascites, but not in A2780 cells from a primary tumor, this led to emergence of a stable population (SKOV-3-R) which in the absence of cisplatin showed increased motility, epithelial-mesenchymal transition (EMT) and expression of cancer stem cell markers CD117, CD44 and ALDH1. Accordingly, the cells formed self-renewing spheres in serum-free stem cell medium. Despite upregulation of mitochondrial mass and cytochrome c, and no upregulation of Bcl-2/Bcl-xL, SKOV-3-R were multiresistant to antineoplastic drugs. Cancer stem cells, or tumor-initiating cells (TICs) are highly chemoresistant and are believed to cause relapse into disseminated and resistant EOC. Our second aim was therefore to target resistance in these TIC-like cells. Resistance could be correlated with upregulation of hexokinase-II and VDAC, which are known to form a survival-promoting mitochondrial complex. The cells were thus sensitive to 3-bromopyruvate, which dissociates hexokinase-II from this complex, and were particularly sensitive to combination treatment with cisplatin at doses down to 0.1 x IC 50. 3-bromopyruvate might thus be of use in targeting the especially aggressive TIC populations.