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Clear cell renal cell carcinoma (ccRCC) is characterized by accumulation of neutral lipids and adipogenic transdifferentiation. We assessed adipokine expression in ccRCC and found that tumor tissues and patient plasma exhibit obesity-dependent elevations of the adipokine chemerin. Attenuation of chemerin by several approaches led to significant reduction in lipid deposition and impairment of tumor cell growth in vitro and in vivo. A multi-omics approach revealed that chemerin suppresses fatty acid oxidation, preventing ferroptosis, and maintains fatty acid levels that activate hypoxia-inducible factor 2α expression. The lipid coenzyme Q and mitochondrial complex IV, whose biogeneses are lipid-dependent, were found to be decreased after chemerin inhibition, contributing to lipid reactive oxygen species production. Monoclonal antibody targeting chemerin led to reduced lipid storage and diminished tumor growth, demonstrating translational potential of chemerin inhibition. Collectively, the results suggest that obesity and tumor cells contribute to ccRCC through the expression of chemerin, which is indispensable in ccRCC biology.Significance:Identification of a hypoxia-inducible factor–dependent adipokine that prevents fatty acid oxidation and causes escape from ferroptosis highlights a critical metabolic dependency unique in the clear cell subtype of kidney cancer. Targeting lipid metabolism via inhibition of a soluble factor is a promising pharmacologic approach to expand therapeutic strategies for patients with ccRCC.See related commentary by Reznik et al., p. 1879.This article is highlighted in the In This Issue feature, p. 1861

Differential expression of genes between ccRCC cluster and normal cluster

Differential expression matrix

Supplementary data

Lipid droplet formation is a defining histological feature in clear-cell renal cell carcinoma (ccRCC) but the underlying mechanisms and importance of this biological behaviour have remained enigmatic. De novo fatty acid (FA) synthesis, uptake and suppression of FA oxidation have all been shown to contribute to lipid storage, which is a necessary tumour adaptation rather than a bystander effect. Clinical studies and mechanistic investigations into the roles of different enzymes in FA metabolism pathways have revealed new metabolic vulnerabilities that hold promise for clinical effect. Several metabolic alterations are associated with worse clinical outcomes in patients with ccRCC, as lipogenic genes drive tumorigenesis. Enzymes involved in the intrinsic FA metabolism pathway include FA synthase, acetyl-CoA carboxylase, ATP citrate lyase, stearoyl-CoA desaturase 1, cluster of differentiation 36, carnitine palmitoyltransferase 1A and the perilipin family, and each might be potential therapeutic targets in ccRCC owing to the link between lipid deposition and ccRCC risk. Adipokines and lipid species are potential biomarkers for diagnosis and treatment monitoring in patients with ccRCC. FA metabolism could potentially be targeted for therapeutic intervention in ccRCC as small-molecule inhibitors targeting the pathway have shown promising results in preclinical models.

Clear cell renal cell carcinoma (ccRCC) is characterized by accumulation of neutral lipids and adipogenic transdifferentiation. We assessed adipokine expression in ccRCC and found that tumor tissues and patient plasma exhibit obesity-dependent elevations of the adipokine chemerin. Attenuation of chemerin by several approaches led to significant reduction in lipid deposition and impairment of tumor cell growth in vitro and in vivo. A multi-omics approach revealed that chemerin suppresses fatty acid oxidation, preventing ferroptosis, and maintains fatty acid levels that activate hypoxia-inducible factor 2α expression. The lipid coenzyme Q and mitochondrial complex IV, whose biogeneses are lipid-dependent, were found to be decreased after chemerin inhibition, contributing to lipid reactive oxygen species production. Monoclonal antibody targeting chemerin led to reduced lipid storage and diminished tumor growth, demonstrating translational potential of chemerin inhibition. Collectively, the results suggest that obesity and tumor cells contribute to ccRCC through the expression of chemerin, which is indispensable in ccRCC biology. Significance: Identification of a hypoxia-inducible factor–dependent adipokine that prevents fatty acid oxidation and causes escape from ferroptosis highlights a critical metabolic dependency unique in the clear cell subtype of kidney cancer. Targeting lipid metabolism via inhibition of a soluble factor is a promising pharmacologic approach to expand therapeutic strategies for patients with ccRCC. See related commentary by Reznik et al., p. 1879. This article is highlighted in the In This Issue feature, p. 1861

Background To our knowledge, we report the first case of a cholangiocarcinoma brain metastasis successfully treated with magnetic resonance imaging (MRI)-guided laser interstitial thermal therapy. Case Description In 2017, a 71-year-old man was diagnosed with unresectable intrahepatic cholangiocarcinoma. In August 2018, a brain MRI scan was performed after a transient episode of altered mental status and revealed a subcentimeter enhancing lesion in the deep white matter of the right cerebellum. Due to lack of symptoms and the small size of the lesion, it was initially observed. However, a follow-up MRI scan at 2.5 months demonstrated increased lesion size with worsening perilesional edema. Given the rarity of cholangiocarcinoma brain metastases and the deep location, the patient underwent stereotactic needle biopsy to confirm the diagnosis followed by laser ablation as a primary treatment for the metastasis. The patient tolerated the surgery well with no complications, and the postoperative course was uneventful. At 16 months postablation, there has been no recurrence or disease progression. Conclusions Although prognosis for these tumors is poor, our result suggests that laser ablation can be an effective treatment for this rare entity and is a representative example of the expanding indications for laser interstitial thermal therapy.

Background Indeterminate dendritic cell tumor (IDCT) is an extremely rare hematologic disorder with poorly understood pathogenesis. Occasionally encountered by hematologists, unusual presentations of IDCT have not been reported in the spine literature. Methods We report a 51-year-old man who presented with a 3-month history of progressively worsening axial thoracic back pain radiating to his sides. Magnetic resonance imaging revealed a 3-cm enhancing mass at the T9 vertebral body with an exophytic component causing significant canal stenosis. Initial percutaneous biopsy revealed histiocytic sarcoma. Results The patient underwent exploratory thoracotomy and en bloc resection of the lesion with T8-10 fusion. Final pathology results revealed IDCT with fibrosis. IDCT immunostaining was partially positive for Langerhans cell marker (positive for S100 and CD1a, but lacked Birbeck granules and Langerin stain) and partially positive for blastic plasmacytoid dendritic cell neoplasm. Additionally, it was positive for CD45, CD68, and CD163. Lymphadenopathy was absent in this patient. Conclusions Although first reported in the 1980s, IDCT has been omitted from most classifications owing to its rarity. Hematologists have debated the cell of origin; it is believed to comprise pre–Langerhans cells, as Birbeck granules are acquired after migration to the epidermis. IDCT remains of indeterminate origin. We report the first case of spinal IDCT. Familiarity with the histologic features is warranted to ensure accurate diagnosis and appropriate treatment.

Clear cell renal cell carcinoma (ccRCC) is the most common renal cancer subtype, characterized by a lipid storage phenotype. We found that carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme of mitochondrial fatty acid (FA) transport, is repressed by hypoxia-inducible factors (HIFs), reducing FA oxidation (FAO). Altering lipid metabolism may be a new therapeutic avenue in ccRCC.

Background:Infratentorial pilocytic astrocytomas are uncommon tumors in adulthood but are thought to be prognostically similar to their pediatric counterparts with excellent overall survival following gross total resection. However, given the relative rarity of these tumors, no management guidelines exist for recurrent adult pilocytic astrocytomas (APAs). This lack of consensus is especially problematic for inoperable recurrences or those with aggressive features concerning for malignant transformation.Case Description:In 2017, a 26-year-old female presented with headaches, nausea, vomiting, and blurry vision. A brain magnetic resonance imaging (MRI) demonstrated a large, well-circumscribed mass within the fourth ventricle causing obstructive hydrocephalus. She underwent near-total resection through a midline suboccipital transtonsillar approach. Pathology demonstrated a World Health Organization Grade 1 pilocytic astrocytoma. Despite initial improvement in her symptoms, she developed worsening headaches and lethargy 10 months after surgery and repeat MRI demonstrated recurrent tumor within the entire ventricular system and the subarachnoid spaces of the left cerebellopontine angle suggesting leptomeningeal spread. Due to the unresectable nature of the recurrence, the patient declined any further intervention and succumbed to her disease 6 months later.Conclusion:We present the first case of a recurrent APA presenting with intraventricular and leptomeningeal spread. Although thought to be a benign neoplasm, close interval follow-up with serial imaging is of essential, especially in those patients with known residual tumor, to prevent aggressive recurrences such as this.

Cerebellar neuronal progenitors undergo a series of divisions before irreversibly exiting the cell cycle and differentiating into neurons. Dysfunction of this process underlies many neurological diseases including ataxia and the most common pediatric brain tumor, medulloblastoma. To better define the pathways controlling the most abundant neuronal cells in the mammalian cerebellum, cerebellar granule cell progenitors (GCPs), we performed RNA-sequencing of GCPs exiting the cell cycle. Time-series modeling of GCP cell cycle exit identified downregulation of activity of the epigenetic reader protein Brd4. Brd4 binding to the Gli1 locus is controlled by Casein Kinase 1δ (CK1 δ)-dependent phosphorylation during GCP proliferation, and decreases during GCP cell cycle exit. Importantly, conditional deletion of Brd4 in vivo in the developing cerebellum induces cerebellar morphological deficits and ataxia. These studies define an essential role for Brd4 in cerebellar granule cell neurogenesis and are critical for designing clinical trials utilizing Brd4 inhibitors in neurological indications., The mechanisms controlling irreversible cell cycle exit in cerebellar granule progenitors (GCPs) have not been fully elucidated. Here, the authors performed RNA-sequencing of GCPs exiting the cell cycle to identify downregulation of Brd4 activity as an early event during cell cycle exit which subsequently regulates Shh activity and is needed for proper cerebellar development

Inflammation is a major contributor to the secondary damage that occurs after spinal cord injury (SCI). The inflammatory response is coordinated by many different signaling modalities including the epigenetic modification of promoters and enhancers. Bromodomain and extraterminal domain-containing proteins (BETs; Brd2, Brd3, Brd4, BrdT) are epigenetic readers that bind acetylated histones to promote transcription of pro-inflammatory genes. BET inhibition is anti-inflammatory in animal models of cancer, rheumatoid arthritis, and coronary artery disease. However, the role of BETs in neuroinflammation remains largely unexplored. In this study, we investigated the role of BETs in promoting inflammation in neural cells and the ability of the BET inhibitor JQ1 to decrease inflammation acutely after SCI. Expression of BET mRNA was assessed via qPCR in purified primary mouse macrophages, astrocytes, neurons, oligodendrocytes, and microglia, as well as in naive, sham-injured, and contusion-injured mouse spinal cord. Brd2, Brd3, and Brd4 mRNA were expressed in all purified primary neural cells and in the uninjured and injured mouse spinal cord. BET inhibition significantly attenuated proinflammatory signaling in all activated cell populations in vitro. To investigate the effects of BET modulation after SCI, the BET inhibitor JQ1 was injected intraperitoneally (30 mg/kg, bidaily) 3 h after spinal cord contusion in adult female C57BL/6 mice. By 3 days post-injury, BET inhibition significantly decreased pro-inflammatory cytokine expression and leukocyte recruitment to the injury site. However, this decrease did not lead to locomotor improvements or smaller lesion size. Taken together, our data implicate BETs as regulators of multiple key pro-inflammatory cytokines, and suggest that BETs can be pharmacologically inhibited to reduce inflammation acutely after SCI.

Background: Medulloblastoma is the most common malignant pediatric brain tumor with variable prognosis due to its clinical and genomic heterogeneity. Despite decades of treatment advances, nearly 40% of children experience tumour recurrence, and 30% will die from this disease. Thus, new drugs and drug combinations need to be developed that effectively treat medulloblastoma. Casein kinase 1δ (CK1δ) is a serine/threonine kinase that controls cell cycle progression, signal transduction and neurogenesis, and we previously reported high levels of CK1δ in mouse models of medulloblastoma. BRD4 is an epigenetic reader protein that controls expression of several oncogenes. We wanted to determine the mechanism through which CK1δ regulates BRD4 activity in medulloblastoma and assess whether a combination of CK1δ and BRD4 inhibitors could be more effective in decreasing medulloblastoma progression in vivo. Methods: Granule cell progenitors (GCPs), medulloblastoma Ptch-/-P53-/- mouse cells and SUFU-/- mouse embryonic fibroblasts were incubated with the CK1δ inhibitor SR-1277 and the phosphorylation levels of BRD4 were determined by WB and its binding to chromatin by ChIP. In vitro phosphorylation studies with human BRD4 purified from E. coli were performed and whether genetic disruption of CK1δ reduces BRD4 phosphorylation was tested. We combined BRD4 and CK1δ inhibitors (JQ1 and SR-1277, respectively) and analysed Gli1 mRNA expression and EdU incorporation. We deleted CK1δ in GCPs in Ptch-/-;P53-/- mouse models of medulloblastoma by breeding these mice with a Tg(Atoh1-Cre);CK1δfl/fl strain. Furthermore, we intracranially transplanted human SHH medulloblastoma PDX cells expressing luciferase in mice, to validate the combination therapy. Results: CK1δ inhibitor treatment and CK1δ knockout reduced BRD4 phosphorylation, suggesting that CK1δ phosphorylates BRD4 and is required for BRD4 recruitment to chromatin. In vitro phosphorylation studies with purified human BRD4 and CK1δ confirmed CK1δ-mediated BRD4 phosphorylation and CK1δ is required for BRD4 phosphorylation at serine 492 and 494 in vivo. Using loss of function studies in GCPs, both CK1δ and BET inhibition reduced BRD4 association with Gli1 promoter, thereby reducing Gli1 mRNA levels. In addition, SR-1277 suppressed SHH signaling downstream of SUFU of medulloblastoma cells, in vitro and in vivo. We also found synergy by combining these compounds in vitro and in reducing tumor burden in the in vivo model with intracranial allografts. Conclusion: Together, our studies validate the CK1δ-BRD4 pathway as a novel target in medulloblastoma. The significance of our work is underscored by the possibility that simultaneous CK1δ-BRD4 inhibition could overcome the resistance observed with BRD4 inhibitors and enhance therapeutic benefit to patients. We are also the first group to demonstrate that CK1δ acts downstream of SHH signalling in SHH-driven medulloblastoma. Citation Format: Sze Kiat Tan, Clara Penas, Cheng-Ming Chiang, David Robbins, Nagi Ayad. CK1δ-BRD4 pathway as novel therapeutic target for SHH subtype of medulloblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4138.

Glioblastoma multiforme (GBM) is the most common malignant adult brain tumor. However, detecting tumor progression via MRI is often inconclusive which can lead to delayed treatment. Therefore, there is an urgent need to develop a peripheral biomarker for GBM. Utilizing single molecule sequencing, we have previously demonstrated that hundreds of long noncoding RNAs, including HOTAIR, are strongly dysregulated in GBM and HOTAIR is critical in GBM cells proliferation. The purpose of this study was to investigate the prognostic and diagnostic values of serum HOTAIR in GBM. The HOTAIR expressions were measured in 32 GBM serum samples and 40 healthy controls using qRT-PCR. The PCR products were subsequently subcloned into pCRTM4-TOPO®TA vectors for DNA sequencing. A ROC curve was generated to examine HOTAIR’s prognostic value and correlations of serum HOTAIR levels with clinicopathological features were analyzed. Serum exosomes were also isolated and validated by Western blot and NanoSight analysis. We further detected serum HOTAIR levels in mice with GBM PDX-39 tumors implanted intracranially. GBM patients had a significantly higher serum HOTAIR expression than those of healthy controls (P