Serum long noncoding RNA HOTAIR as a novel diagnostic and prognostic biomarker in glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most common and aggressive malignant adult primary brain tumor. Despite surgical resection followed by radiotherapy and chemotherapy, the median survival rate is approximately 14 months. Although experimental therapies are in clinical trials for GBM, there is an urgent need for a peripheral GBM biomarker for measuring treatment response. As we have previously demonstrated that the long noncoding RNA HOX Transcript Antisense Intergenic RNA, or HOTAIR, is dysregulated in GBM and required for GBM cell proliferation, we hypothesized that HOTAIR expression may be utilized as a peripheral biomarker for GBM. HOTAIR expression was measured in serum from 43 GBM and 40 controls using quantitative real-time PCR (qRT-PCR). The PCR products were subsequently subcloned into pCR™4-TOPO®TA vectors for DNA sequencing. A ROC curve was also generated to examine HOTAIR's prognostic value. The amount of HOTAIR in serum exosomes and exosome-depleted supernatant was calculated by qRT-PCR. The relative HOTAIR expression was also investigated in 15 pairs of GBM serum and tumors. We detected HOTAIR in serum from GBM patients. HOTAIR levels in serum samples from GBM patients was significantly higher than in the corresponding controls (P < 0.0001). The area under the ROC curve distinguishing GBM patients from controls was 0.913 (95% CI: 0.845-0.982, P < 0.0001), with 86.1% sensitivity and 87.5% specificity at the cut-off value of 10.8. HOTAIR expression was significantly correlated with high grade brain tumors. In addition, Pearson correlation analysis indicated a medium correlation of serum HOTAIR levels and the corresponding tumor HOTAIR levels (r = 0.734, P < 0.01). We confirmed via sequencing that the amplified HOTAIR from serum contained the HOTAIR sequence and maps to the known HOTAIR locus at 12q13. The serum-derived exosomes contain HOTAIR and the purified exosomes were validated by western blot and nanoparticle tracking analysis. Importantly, our results demonstrate that serum HOTAIR can be used as a novel prognostic and diagnostic biomarker for GBM.

GPR1 and CMKLR1 control lipid metabolism to support development of clear cell renal cell carcinoma.

Clear cell renal cell carcinoma (ccRCC), the most common type of kidney cancer, is largely incurable in the metastatic setting. ccRCC is characterized by excessive lipid accumulation that protects cells from stress and promotes tumor growth, suggesting that the underlying regulators of lipid storage could represent potential therapeutic targets. Here, we evaluated the regulatory roles of GPR1 and CMKLR1, two G-protein coupled receptors of the pro-tumorigenic adipokine chemerin that is involved in ccRCC lipid metabolism. Both genetic and pharmacological suppression of either receptor suppressed lipid formation and induced multiple forms of cell death, including apoptosis, ferroptosis and autophagy, significantly impeding ccRCC growth in cell lines and patient derived xenograft (PDX) models. Comprehensive lipidomic and transcriptomic profiling of receptor competent and depleted cells revealed overlapping and unique signaling of the receptors granting control over triglyceride synthesis, ceramide production, and fatty acid saturation and class production. Mechanistically, the receptors both enforced suppression of the triglyceride lipase ATGL but also demonstrated distinct functions, such as the unique ability of CMKLR1 to control lipid uptake through regulation of SREBP1c and the CD36 scavenger receptor. Treating PDX models with the CMKLR1-targeting small molecule α-NETA led to a dramatic reduction of tumor growth, lipid storage, and clear cell morphology. Together, these findings provide mechanistic insight into lipid regulation in ccRCC and identify a targetable axis at the core of the histological definition of this tumor that could be exploited therapeutically.

Fatty acid metabolism reprogramming in ccRCC: mechanisms and potential targets.

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.

Recurrent adult pilocytic astrocytoma presenting with intraventricular and leptomeningeal spread.

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.

Obesity-Dependent Adipokine Chemerin Suppresses Fatty Acid Oxidation to Confer Ferroptosis Resistance.

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.

Lipid in Renal Carcinoma: Queen Bee to Target?

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.

Complete Regression of a Solitary Cholangiocarcinoma Brain Metastasis Following Laser Interstitial Thermal Therapy.

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.

Time series modeling of cell cycle exit identifies Brd4 dependent regulation of cerebellar neurogenesis.

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.

Bromodomain and extraterminal domain-containing protein inhibition attenuates acute inflammation after spinal cord injury.

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 naïve, 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.

Drug Repositioning in Glioblastoma: A Pathway Perspective.

Glioblastoma multiforme (GBM) is the most malignant primary adult brain tumor. The current standard of care is surgical resection, radiation, and chemotherapy treatment, which extends life in most cases. Unfortunately, tumor recurrence is nearly universal and patients with recurrent glioblastoma typically survive <1 year. Therefore, new therapies and therapeutic combinations need to be developed that can be quickly approved for use in patients. However, in order to gain approval, therapies need to be safe as well as effective. One possible means of attaining rapid approval is repurposing FDA approved compounds for GBM therapy. However, candidate compounds must be able to penetrate the blood-brain barrier (BBB) and therefore a selection process has to be implemented to identify such compounds that can eliminate GBM tumor expansion. We review here psychiatric and non-psychiatric compounds that may be effective in GBM, as well as potential drugs targeting cell death pathways. We also discuss the potential of data-driven computational approaches to identify compounds that induce cell death in GBM cells, enabled by large reference databases such as the Library of Integrated Network Cell Signatures (LINCS). Finally, we argue that identifying pathways dysregulated in GBM in a patient specific manner is essential for effective repurposing in GBM and other gliomas.

Indeterminate Dendritic Cell Tumor in Thoracic Spine: A Case Report.

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.