No abstract

Surgical resection is a mainstay in the treatment of malignant brain tumors. Surgeons, however, face great challenges in distinguishing tumor margins due to their infiltrated nature. Here, a pair of gold nanoprobes that enter a brain tumor by crossing the blood-brain barrier is developed. The acidic tumor environment triggers their assembly with the concomitant activation of both magnetic resonance (MR) and surface-enhanced resonance Raman spectroscopy (SERRS) signals. While the bulky aggregates continuously trap into the tumor interstitium, the intact nanoprobes in normal brain tissue can be transported back into the blood stream in a timely manner. Experimental results show that physiological acidity triggers nanoparticle assembly by forming 3D spherical nanoclusters with remarkable MR and SERRS signal enhancements. The nanoprobes not only preoperatively define orthotopic glioblastoma xenografts by magnetic resonance imaging (MRI) with high sensitivity and durability in vivo, but also intraoperatively guide tumor excision with the assistance of a handheld Raman scanner. Microscopy studies verify the precisely demarcated tumor margin marked by the assembled nanoprobes. Taking advantage of the nanoprobes' rapid excretion rate and the extracellular acidification as a hallmark of solid tumors, these nanoprobes are promising in improving brain-tumor surgical outcome with high specificity, safety, and universality.

Subchronic exposure to arsenic increases the incidence of human cancers such as skin, lung, colon, and rectal cancer. The mechanism for arsenic-induced tumorigenesis is still not clear. It is generally believed that DNA damage and genomic instability, generated by arsenic-promoted oxidative stress, account largely for this process. The major sources of reactive oxygen species (ROS) are arsenic-damaged mitochondria. Autophagy is a catabolic process functioning in turnover of long-lived proteins and dysfunctional organelles such as mitochondria. Defects of autophagy under stress conditions promote genomic instability and increase the risk of tumorigenesis. In the present study using a human bronchial epithelial cell line, BEAS-2B cells, we investigated the role of autophagy in arsenic-induced cell transformation, an important step in arsenic tumorigenesis. Our results show that subchronic arsenic exposure induces BEAS-2B cell transformation accompanied with increased ROS generation and autophagy activation. However, the patterns for ROS and autophagy alteration are different. Arsenic exposure generated a prolonged and steady increase of ROS levels, whereas the activation of autophagy, after an initial boost by arsenic administration, decreases in response to subchronic arsenic exposure, although the activity is still higher than a nontreated control. Further stimulation of autophagy increases mitochondria turnover and decreases ROS generation and arsenic-induced cell transformation. Contrarily, inhibition of autophagy activity decreases mitochondria turnover and enhances arsenic-induced ROS generation and cell transformation. In addition, the mammalian target of rapamycin signaling pathway is involved in arsenic-mediated autophagy activation. Our results suggest that autophagy is a cell self-protective mechanism against arsenic-induced cell transformation.

Chronic inflammation has been implicated as an etiological factor in cancer, whereas autophagy may help preserve cancer cell survival but exert anti-inflammatory effects. How these phenomena interact during carcinogenesis remains unclear. We explored this question in a human bronchial epithelial cell-based model of lung carcinogenesis that is mediated by sub-chronic exposure to arsenic. We found that sustained overexpression of the pro-inflammatory interleukin IL-6 promoted arsenic-induced cell transformation by inhibiting autophagy. Conversely, strategies to enhance autophagy counteracted the effect of IL-6 in the model. These findings were confirmed and extended in a mouse model of arsenic-induced lung cancer. Mechanistic investigations suggested that mTOR inhibition contributed to the activation of autophagy, whereas IL-6 overexpression was sufficient to block autophagy by supporting Beclin-1/Mcl-1 interaction. Overall, our findings argued that chronic inflammatory states driven by IL-6 could antagonize autophagic states that may help preserve cancer cell survival and promote malignant progression, suggesting a need to uncouple inflammation and autophagy controls to enable tumor progression.

Background:We investigated the role of microRNAs in ethanol neurotoxicity in the developing cerebellum. Results: MiR-29b regulates ethanol-induced apoptosis of cerebellar granule neurons in the developing cerebellum via SP1/ RAX/PKR cascade. Conclusion: MiR-29b plays an important role in ethanol neurotoxicity in the developing cerebellum. Significance: MiR-29b may be a new preventive/therapeutic target for fetal alcohol spectrum disorders.

Tripartite motif (TRIM) proteins are involved in tumorigenesis. Here, we examined the expression, biological function, and clinical significance of tripartite motif containing 28 (TRIM28) in glioma, a locally aggressive brain tumor. First, TRIM28 expression was significantly higher in glioma (n = 138) than in non-glioma controls (n = 6). TRIM28 expression was positively correlated with tumor malignancy, and associated with poor overall survival (OS) and progression-free survival (PFS). Notably, TRIM28 expression was negatively correlated with p21 expression in patients with glioblastoma multiforme (GBM). A multivariate analysis that included relevant measures indicated that high TRIM28 expression is an independent prognostic factor for poor OS and PFS in GBM patients. In experiments with cultured glioma cells, down-regulating TRIM28 with shRNA increased p21 expression, and induced cell cycle arrest at the G1 phase. In a xenograft model, down-regulating TRIM28 suppressed tumor growth. These results indicate that over-expression of TRIM28 is associated with poor outcome in glioma patients.

Forkhead box protein 3 (Foxp3) is known as a specific marker for regulatory T cells which contribute to immunosuppression in tumor microenvironment. However, existing studies regarding clinical significance of Foxp3+ tumor-infiltrating lymphocytes (TILs) in glioblastoma (GBM) remained discrepant. In this study, we aimed to explore whether this subtype of TILs correlated with prognosis in patients with GBM. Foxp3+ TILs as well as CD8+ ones were detected by immunohistochemistry on paraffin-embedded tumor samples from 62 patients. Staining for p53, MGMT and Ki-67 were also performed. The correlation of TIL subtypes with clinicopathologic features were analyzed. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan–Meier method and compared using log-rank test. Independent prognostic factors for PFS and OS were determined through univariate and multivariate analysis. Significant correlation was found between Foxp3 and CD8 expression (P = 0.003), but not between TIL subtypes and clinicopathologic characteristics. Patients with higher density of Foxp3+ TILs showed relatively shorter PFS (P < 0.001) and OS (P = 0.003) whereas patients with higher density of CD8+ TILs obtained no significant differences in survival. Survival analysis based on molecular classifications further clarified these predictive values. Univariate and multivariate analysis revealed that frequency of Foxp3+ TILs was probably associated with both PFS (P = 0.002) and OS (P = 0.003). In conclusion, the results suggest that Foxp3 positive infiltrates could provide an independent predictive factor in GBM.Electronic supplementary materialThe online version of this article (doi:10.1007/s11060-013-1314-0) contains supplementary material, which is available to authorized users.

Surgery is a mainstay to treat malignant brain tumors. However, due to the infiltrative nature of these tumors, it is a great challenge for surgeons to accurately identify and excise all the tumor foci. EGFRvIII, a variant of epidermal growth factor receptor (EGFR), is found in 20% of glioblastoma cases, which is the brain tumor with the highest malignancy. In this study, we developed an EGFRvIII-targeted nanoprobe to guide glioblastoma surgery by pre-operatively defining the tumor boundary via magnetic resonance imaging (MRI) and intra-operatively guiding resection by surface-enhanced resonance Raman scattering (SERRS) imaging. In vivo MRI studies show that this nanoprobe delineates an orthotopic EGFRvIII+ U87MG glioblastoma xenograft with a higher target to background ratio than the control nanoprobe without targeting specificity. With the assistance of a handheld Raman scanner, this nanoprobe successfully guided EGFRvIII+ glioblastoma resection by tracking its characteristic SERRS signal peaks. Ex vivo Raman microscopy and histological images verified that this nanoprobe precisely demarcated the glioblastoma boundary and no residual neoplastic foci were observed in the tumor bed. This dual-modal nanoprobe not only precisely guided glioblastoma resection, but also overcame the brain shift induced false-positive signal by real-timely co-registering pre-operative and intra-operative images. This nanoprobe is promising for the improvement in diagnostic accuracy and surgical outcome of EGFRvIII+ glioblastoma.