Interaction of RAGE (the receptor for advanced glycation endproducts) with its ligands can promote tumor progression, invasion, and angiogenesis. Although blocking RAGE signaling has been proposed as a potential anticancer strategy, functional contributions of RAGE expression in the tumor microenvironment (TME) have not been investigated in detail. Here, we evaluated the effect of genetic depletion of RAGE in TME on the growth of gliomas. In both invasive and noninvasive glioma models, animal survival was prolonged in RAGE knockout (Ager^−/−) mice. However, the improvement in survival in Ager^−/− mice was not due to changes in tumor growth rate but rather to a reduction in tumor-associated inflammation. Furthermore, RAGE ablation in the TME abrogated angiogenesis by downregulating the expression of proangiogenic factors, which prevented normal vessel formation, thereby generating a leaky vasculature. These alterations were most prominent in noninvasive gliomas, in which the expression of VEGF and proinflammatory cytokines were also lower in tumor-associated macrophages (TAM) in Ager^−/− mice. Interestingly, reconstitution of Ager^−/− TAM with wild-type microglia or macrophages normalized tumor vascularity. Our results establish that RAGE signaling in glioma-associated microglia and TAM drives angiogenesis, underscoring the complex role of RAGE and its ligands in gliomagenesis. Cancer Res; 74(24); 7285–97. ©2014 AACR.

Background: Imperatorin (IM) is a furanocoumarin isolated from the root of Angelica dahurica, which is reported to have anticonvulsant and anticancer effects. In this study, the antiproliferative effect of IM on 9 human cancer cell lines was examined, and human hepatoma HepG2 cells were chosen as the target for preferential killing by IM. Particularly, the mechanism of IM-induced apoptosis and in vivo animal effects were also studied. Methods: Cell viability was measured using MTT assay, and apoptosis was detected by Hoechst staining, annexin V-PI staining, and DNA laddering assay. Mitochondrial membrane potential was detected by JC-1 staining. Western blot analysis was employed to detect the expression of apoptosis-related proteins. In addition, the in vivo anticancer effect of IM was examined in nude mice bearing HepG2 cells. Results: IM inhibited the proliferation of HepG2 cells through apoptosis induction in a time- and dose-dependent manner by observation of the nuclear morphology, DNA fragmentation, phosphatidylserine externalization, loss of mitochondrial membrane potential, release of cytochrome c into cytosol, and activation of caspase-3, caspase-8, caspase-9, and poly(ADP-ribose) polymerase cleavage. As cell death could partly be prevented by the caspase-8 or caspase-9 inhibitor and was evidenced by the results of Western blot analysis, our results also suggest that IM-induced apoptosis is mediated through both death receptor and mitochondrial pathways. In the animal model, IM was found to effectively suppress tumor growth by 31.93 and 63.18% at dosages of 50 and 100 mg/kg, respectively, after treatment for 14 days. No significant weight loss or toxicity to the hosts was found. Conclusions: IM can function as a cancer suppressor by inducing apoptosis in HepG2 cells through both death-receptor- and mitochondria-mediated pathways. Furthermore, the in vivo antitumor activities of IM are significant with negligible weight loss and damage to the host.

Compared with conventional optical microscopy techniques, mass spectrometry imaging (MSI) or imaging mass spectrometry (IMS) is a powerful, label-free analytical technique, which can sensitively and simultaneously detect, quantify, and map hundreds of biomolecules, such as peptides, proteins, lipid, and other organic compounds in cells and tissues. So far, although several soft ionization techniques, such as desorption electrospray ionization (DESI) and secondary ion mass spectrometry (SIMS) have been used for imaging biomolecules, matrix-assisted laser desorption/ionization (MALDI) is still the most widespread MSI scanning method. Here, we aim to provide a comprehensive review of MALDI-MSI with an emphasis on its advances of the instrumentation, methods, application, and future directions in single cell and biological tissues.

Purpose: S100B is member of a multigenic family of Ca²⁺-binding proteins, which is overexpressed by gliomas. Recently, we showed that low concentrations of S100B attenuated microglia activation through the induction of Stat3. We hypothesized that overexpression of S100B in gliomas could promote tumor growth by modulating the activity of tumor-associated macrophages (TAM). Experimental Design: We stably transfected GL261 glioma cell lines with constructs that overexpressed (S100B^high) or underexpressed (S100B^low) S100B and compared their growth characteristics to intracranial wild-type (S100B^wt) tumors. Results: Downregulation of S100B in gliomas had no impact on cell division in vitro but abrogated tumor growth in vivo. Interestingly, compared to S100B^low tumors, S100B^wt and S100B^high intracranial gliomas exhibited higher infiltration of TAMs, stronger inflammatory cytokine expression, and increased vascularity. To identify the potential mechanisms involved, the expression of the S100B receptor, receptor for advanced glycation end products (RAGE), was evaluated in gliomas. Although S100B expression induced RAGE in vivo, RAGE ablation in mice did not significantly inhibit TAM infiltration into gliomas, suggesting that other pathways were involved in this process. To evaluate other mechanisms responsible for TAM chemoattraction, we then examined chemokine pathways and found that C-C motif ligand 2 (CCL2) was upregulated in S100B^high tumors. Furthermore, analysis of The Cancer Genome Atlas's glioma data bank showed a positive correlation between S100B and CCL2 expression in human proneural and neural glioma subtypes, supporting our finding. Conclusions: These observations suggest that S100B promotes glioma growth by TAM chemoattraction through upregulation of CCL2 and introduces the potential utility of S100B inhibitors for glioma therapy. Clin Cancer Res; 19(14); 3764–75. ©2013 AACR.