Qinglin Liu

Hypoxia promotes glioma-associated macrophage infiltration via periostin and subsequent M2 polarization by upregulating TGF-beta and M-CSFR

Tumor-associated macrophages (TAMs) are enriched in gliomas and help create a tumor-immunosuppressive microenvironment. A distinct M2-skewed type of macrophages makes up the majority of glioma TAMs, and these cells exhibit pro-tumor functions. Gliomas contain large hypoxic areas, and the presence of a correlation between the density of M2-polarized TAMs and hypoxic areas suggests that hypoxia plays a supportive role during TAM recruitment and induction. Here, we investigated the effects of hypoxia on human macrophage recruitment and M2 polarization. We also investigated the influence of the HIF inhibitor acriflavine (ACF) on M2 TAM infiltration and tumor progression in vivo. We found that hypoxia increased periostin (POSTN) expression in glioma cells and promoted the recruitment of macrophages. Hypoxia-inducible POSTN expression was increased by TGF-α via the RTK/PI3K pathway, and this effect was blocked by treating hypoxic cells with ACF. We also demonstrated that both a hypoxic environment and hypoxia-treated glioma cell supernatants were capable of polarizing macrophages toward a M2 phenotype. ACF partially reversed the M2 polarization of macrophages by inhibiting the upregulation of M-CSFR in macrophages and TGF-β in glioma cells under hypoxic conditions. Administering ACF also ablated tumor progression in vivo. Our findings reveal a mechanism that underlies hypoxia-induced TAM enrichment and M2 polarization and suggest that pharmacologically inhibiting HIFs may reduce M2-polarized TAM infiltration and glioma progression.

A novel tumor-promoting mechanism of IL6 and the therapeutic efficacy of tocilizumab: Hypoxia-induced IL6 is a potent autophagy initiator in glioblastoma via the p-STAT3-MIR155-3p-CREBRF pathway

ABSTRACT Hypoxia induces protective autophagy in glioblastoma cells and new therapeutic avenues that target this process may improve the outcome for glioblastoma patients. Recent studies have suggested that the autophagic process is upregulated in glioblastomas in response to extensive hypoxia. Hypoxia also induces the upregulation of a specific set of proteins and microRNAs (miRNAs) in a variety of cell types. IL6 (interleukin 6), an inflammatory autocrine and paracrine cytokine that is overexpressed in glioblastoma, has been reported to be a biomarker for poor prognosis because of its tumor-promoting effects. Here, we describe a novel tumor-promoting mechanism of IL6, whereby hypoxia-induced IL6 acts as a potent initiator of autophagy in glioblastoma via the phosphorylated (p)-STAT3-MIR155-3p pathway. IL6 and p-STAT3 levels correlated with the abundance of autophagic cells and HIF1A levels in human glioma tissues and with the grade of human glioma, whereas inhibition of exogenous or endogenous IL6 repressed autophagy in glioblastoma cells in vitro. Knockdown of endogenous MIR155-3p inhibited IL6-induced autophagy, and enforced expression of MIR155-3p restored the anti-autophagic activity of IL6 inhibitors. We show that the hypoxia-IL6-p-STAT3-MIR155-3p-CREBRF-CREB3-ATG5 pathway plays a central role in malignant glioma progression, with blockade of the IL6 receptor by tocilizumab demonstrating a certain level of therapeutic efficacy in a xenograft model in vivo, especially in combination with temozolomide. Moreover, tocilizumab inhibits autophagy by promoting tumor apoptosis. Collectively, our findings provide new insight into the molecular mechanisms underlying hypoxia-induced glioma cell autophagy and point toward a possible efficacious adjuvant therapy for glioblastoma patients.

MicroRNA-584-3p, a novel tumor suppressor and prognostic marker, reduces the migration and invasion of human glioma cells by targeting hypoxia-induced ROCK1

Here, we report that microRNA-584-3p (miR-584-3p) is up-regulated in hypoxic glioma cells and in high-grade human glioma tumors (WHO grades III–IV) relative to normoxic cells and to low-grade tumors (WHO grades I–II), respectively. The postoperative survival time was significantly prolonged in the high-grade glioma patients with high miR-584-3p expression compared with those with low miR-584-3p expression. miR-584-3p may function as a potent tumor suppressor and as a prognostic biomarker for malignant glioma. However, the molecular mechanisms underlying these properties remain poorly understood. Our mechanistic studies revealed that miR-584-3p suppressed the migration and invasion of glioma cells by disrupting hypoxia-induced stress fiber formation. Specifically, we have found that ROCK1 is a direct and functionally relevant target of miR-584-3p in glioma cells. Our results have demonstrated a tumor suppressive function of miR-584-3p in glioma, in which it inhibits the migration and invasion of tumor cells by antagonizing hypoxia-induced, ROCK1-dependent stress fiber formation. Our findings have potential implications for glioma gene therapy and suggest that miR-584-3p could represent a prognostic indicator for glioma.

MicroRNA-Let-7f reduces the vasculogenic mimicry of human glioma cells by regulating periostin-dependent migration

The present study was the first to examine the effect of microRNA-Let-7f (miR-Let-7f) inhibiting vasculogenic mimicry (VM) of human glioma cells. The postoperative survival time was significantly poor in VM-positive glioma patients compared with those without VM. Thus, it is reasonable to postulate that miR-Let-7f functions as a potent tumor suppressor by inhibiting glioma VM. However, the molecular mechanisms involved remain poorly clarified. Our preliminary studies revealed that miR-Let-7f suppressed VM by disturbing periostin (POSTN)-induced migration of glioma cells. Our results clearly demonstrated that inhibiting the pro-migratory function of POSTN by the overexpression of miR-Let-7f significantly reduced the formation of VM. Our findings suggest that miR-Let-7f may serve as a potential complementary therapeutic target in the anti‑angiogenesis treatment of gliomas via suppressing VM.

CREBRF is a potent tumor suppressor of glioblastoma by blocking hypoxia-induced autophagy via the CREB3/ATG5 pathway

Hypoxia induces protective autophagy in advanced glioblastoma cells, and targeting this process may improve the outcome for glioblastoma patients. Recent studies have suggested that the autophagic process is upregulated in glioblastoma cells in response to extensive hypoxia. Here, we describe a novel tumor suppressor in glioblastoma cells, whereby hypoxia downregulated CREBRF expression and acts as a potent inhibitor of autophagy in glioblastoma cells via the CREB3/ATG5 pathway. Our results demonstrate that CREBRF expression negatively correlates with autophagic and HIF-1α levels in different grade gliomas. Given that CREBRF is a negative regulator of CREB3, CREB3 knockdown also repressed hypoxia-induced autophagy in glioblastoma cells inxa0vitro. Collectively, our findings provide new insight into the molecular mechanisms underlying hypoxia-induced glioblastoma cell autophagy and indicate that the hypoxia/CREBRF/CREB3/ATG5 pathway plays a central role in malignant glioma progression.

Intrasylvian/Intracerebral Hematomas Associated with Ruptured Middle Cerebral Artery Aneurysms: A Single-Center Series and Literature Review

OBJECTIVEnRuptured middle cerebral artery (MCA) aneurysms usually lead to subarachnoid hemorrhage (SAH), and several cases have shown concomitant intrasylvian or intracerebral hematomas. The objective of this study was to compare the clinical and radiographic characteristics with their different outcomes.nnnMETHODSnThe charts of 30 consecutive patients with ruptured MCA aneurysm-related intracranial hematoma were retrospectively reviewed. These patients were dichotomized into an intrasylvian hematoma (ISH) group and an intracerebral hematoma (ICH) group by the presence of intrahematomal contrast-enhancing vessel; for patients under open surgery, hematoma type was further confirmed by intraoperative observation. The characteristics were compared between these 2 groups (ie, age, gender, history of hypertension, history of smoking, systolic pressure at admission, hematoma volume, size and side of aneurysms, the angle between the pointing direction of the aneurysm and the MCA trunk [denoted as α], middle line shifting, treatment modality, and outcome). All the angles are measured in the anterior-posterior projection.nnnRESULTSnIn our series, only hematoma volume, the angle α, and the middle line shift showed statistical significance regarding prognosis between 2 hematoma groups. An angle α between 109.0°and 216.0° is associated with ISH, whereas aneurysm with an angle beyond this range indicates ICH. In our series, patients in the ICH group had a larger hematoma volume compared with the ISH patients (33.3 ± 17.6 vs. 11.5 ± 10.5; Pxa0= 0.002). There exists no statistical difference regarding prognosis between these 2 groups, even although there is a trend toward worse recovery for patients in the ISH group (Glasgow Outcome Scale score, 3.0 ± 1.3 vs. 3.8 ± 1.9; Pxa0= 0.07).nnnCONCLUSIONSnIn our series, the prognosis of patients with ICH was worse than that of patients with ISH. Early discrimination of these 2 types of hematoma helps to predict future outcome; an angle (between the pointing direction of aneurysm and the MCA trunk) between 109.0°and 216.0° is associated with ISH, whereas aneurysm with an angle beyond this range suggests ICH.

Immunosuppressive effects of hypoxia-induced glioma exosomes through myeloid-derived suppressor cells via the miR-10a/ Rora and miR-21/ Pten Pathways

While immunosuppressive environments mediated by myeloid-derived suppressor cells (MDSCs) have been well documented in glioma patients, the mechanisms of MDSC development and activation have not been clearly defined. Here, we elucidated a role for glioma-derived exosomes (GDEs) in potentiating an MDSC pathway. We isolated normoxia-stimulated and hypoxia-stimulated GDEs and studied their MDSC induction abilities in vivo and in vitro. Analyses of spleen and bone marrow MDSC proportions (flow cytometry) and reactive oxygen species (ROS), arginase activity, nitric oxide (NO), T-cell proliferation and immunosuppressive cytokine (IL-10 and TGF-β, ELISA) levels were used to assess MDSC expansion and functional capacity. We also performed microRNA (miRNA) sequencing analysis of two types of GDEs to find miRNAs that potentially mediate the development and activation of MDSCs. GDE miRNA intracellular signaling in MDSCs was also studied. Hypoxia promoted the secretion of GDEs, and mouse MDSCs could uptake GDEs. Hypoxia-stimulated GDEs had a stronger ability to induce MDSCs than N-GDEs. The hypoxia-inducible expression of miR-10a and miR-21 in GDEs mediated GDE-induced MDSC expansion and activation by targeting RAR-related orphan receptor alpha (RORA) and phosphatase and tensin homolog (PTEN). Mice inoculated with miR-10a or miR-21 knockout glioma cells generated fewer MDSCs than those inoculated with normal glioma cells. These data elucidated a mechanism by which glioma cells influence the differentiation and activation of MDSCs via exosomes and demonstrated how local glioma hypoxia affects the entirety of tumor immune environments.

Homeobox‑containing protein 1 loss is associated with clinicopathological performance in glioma

Homeobox-containing protein 1 (HMBOX1) is a novel member of the homeobox family, and abnormal expression of HMBOX1 has been observed in several types of carcinoma. A total of 144xa0cases of confirmed glioma diagnoses were included in the present study. Grading was performed according to the World Health Organization (WHO) grading system for central nervous system neoplasm. Immunohistochemical staining of HMBOX1, proliferation marker protein Ki‑67 (Ki‑67) and microvessel density (MVD) was performed, and scores were calculated. HMBOX1 mRNA levels were detected using the reverse transcription quantitative polymerase chain reaction. It was identified that the expression of HMBOX1 was reduced in glioma tissue compared with normal brain tissue (P<0.05). The expression of HMBOX1 was downregulated significantly in WHO gradexa0IV tumors compared with WHO grades II and III (P<0.05). HMBOX1 expression was significantly correlated with WHO grade, Karnofsky Performance Score, MVD and Ki‑67 expression; however, not associated with age or gender. Log‑rank testing did not demonstrate that HMBOX1 expression was associated with prognosis. In conclusion, HMBOX1 may be a potential diagnostic marker in glioma.

Intrasellar and Suprasellar Schwannoma Misdiagnosed as Pituitary Macroadenoma: A Case Report and Review of the Literature.

BACKGROUNDnIntracranial schwannomas usually arise from sensory nerves with a predilection for the trigeminal nerve and the vestibular component of the eighth cranial nerve (VIII). Schwannoma arising in the sella and extending into the suprasellar region is exceedingly rare and easily misdiagnosed as pituitary macroadenoma. Only 26 cases of intrasellar schwannomas have been reported in the literature.nnnCASE DESCRIPTIONnA patient with an intrasellar schwannoma and suprasellar extension was presurgically diagnosed as having pituitary macroadenoma. Subtotal excision of the lesion was performed via an endoscopic endonasal transsphenoidal approach. Histopathology showed schwannoma. His symptoms improved after surgery. Magnetic resonance imaging 6 months after surgery showed a remnant schwannoma in the sella.nnnCONCLUSIONSnAlthough schwannoma in the sellar region is rare, it remains an important differential diagnosis because of different surgical approaches.

Traumatic Anterior Cerebral Artery Pseudoaneurysmal Epistaxis

BACKGROUNDnPseudoaneurysmal epistaxis is a rare but emergent condition. We report a case of traumatic anterior cerebral artery pseudoaneurysmal epistaxis and review the published literature.nnnCASE DESCRIPTIONnA 49-year-old man sustained severe head trauma. He was diagnosed with multiple skull bone fractures, left subdural hematoma, subarachnoid hemorrhage, pneumocephalus, and right frontal hematoma. Subdural hematoma evacuation was done at a local hospital. In the following months, he experienced repeated epistaxis that required nasal packing to stop the bleeding. Digital subtraction angiography showed an anterior cerebral artery pseudoaneurysm protruding into the posterior ethmoid sinus. Embolization of the aneurysm was performed with microcoils, and the parent artery was occluded by thrombosis. The patient presented 1 month later with another epistaxis episode. Digital subtraction angiography showed recanalization of the parent artery and recurrence of the aneurysm. The parent artery was occluded for the second time with coils and Onyx embolic agent.nnnCONCLUSIONSnPseudoaneurysmal epistaxis is rare, and this is the first report of an anterior cerebral artery pseudoaneurysm that manifested with epistaxis. Endovascular intervention has become the first choice of treatment for this disease. The high recurrence rate is the main disadvantage of endovascular intervention. Aneurysm trapping with bypass surgery is another treatment option.