Differential Transcriptome Responses in Human THP-1 Macrophages Following Exposure to T98G and LN-18 Human Glioblastoma Secretions: A Simplified Bioinformatics Approach to Understanding Patient-Glioma-Specific Effects on Tumor-Associated Macrophages.

A common theme in glioma disease progression is robust infiltration of immune cells within the tumor microenvironment, resulting in a state of chronic inflammation. This disease state is characterized by an abundance of CD68+ microglia and CD163+ bone marrow-derived macrophages with the greater the percentage of CD163+ cells, the poorer the prognosis. These macrophages are "cold," in that their phenotype is of an alternatively activated state (M0-M2-like) supporting tumor growth rather than being engaged with classically activated, pro-inflammatory, and anti-tumor activities, referred to as "hot", or M1-like. Herein, we have developed an in vitro approach that uses two human glioma cell lines, T98G and LN-18, which exhibit a variety of differing mutations and characteristics, to demonstrate their disparate effects on differentiated THP-1 macrophages. We first developed an approach to differentiating THP-1 monocytes to macrophages with mixed transcriptomic phenotypes we regard as M0-like macrophages. We then found that supernatants from the two different glioma cell lines induced different gene expression profiles in THP-1 macrophages, suggesting that from patient to patient, gliomas may be considered as different diseases. This study suggests that in addition to standard glioma treatment modalities, transcriptome profiling of the effects of cultured glioma cells on a standard THP-1 macrophage in vitro model may lead to future druggable targets that aim to reprogram tumor-associated macrophages towards an anti-tumor phenotype.

GLI1 is involved in HIF-1α-induced migration, invasion, and epithelial-mesenchymal transition in glioma cells.

INTRODUCTION: Glioma is characterized by hypoxia that activates the hypoxia inducible factor (HIF) pathway and controls a myriad of genes that drive cancer progression. HIF-1α promotes GLI1 transferring to the nucleus by activating the hedgehog pathway under hypoxic conditions. However, their mechanisms in glioma cells under hypoxia remain unknown. MATERIAL AND METHODS: Human glioma cell lines (LN229 and LN18) were transfected with HIF-1α or GLI1-specific short hairpin RNAs (shRNAs) and cultured under normoxic or hypoxic conditions. The protein levels of HIF-1α, GLI1, and epithelial-mesenchymal transition (EMT) markers including E-cadherin and vimentin were measured by Western blot analysis. RT-qPCR analysis was performed for the detection of HIF-1α and GLI1 mRNA expression. Cell migratory and invasive capacities were evaluated by wound healing and Transwell assays, respectively. RESULTS: Hypoxia blocked the breakdown of the HIF-1α protein and upregulated GLI1 expression in glioma cells. Downregulation of HIF-1α expression inhibited hypoxia-induced cell migration and invasion, as well as reversed the effects of hypoxia on GLI1, E-cadherin, and vimentin expression in LN229 and LN18 cells. Depletion of GLI1 inhibited glioma cell migration and invasion induced by hypoxia. Silenced GLI1 did not affect HIF-1α expression but completely offset hypoxia-regulated expression of E-cadherin and vimentin in glioma cells. CONCLUSIONS: GLI1 is involved in HIF-1α-induced migration, invasion, and EMT in glioma cells, thus revealing a novel molecular mechanism for glioma research.

An endogenous and ectopic expression of metabotropic glutamate receptor 8 (mGluR8) inhibits proliferation and increases chemosensitivity of human neuroblastoma and glioma cells.

The present study aimed to determine the role of metabotropic glutamate receptor 8 (mGluR8) in tumor biology. Using various molecular approaches (RNAi or GRM8 cDNA), cell clones with downregulated (human neuroblastoma SH-SY5Y and human glioma LN229) or overexpressed (human glioma U87-MG and LN18 cell lines) mGluR8 were generated. Next, comparative studies on cell proliferation and migration rates, induction of apoptosis and chemosensitivity were performed among these clones. The mGluR8-downregulated SH-SY5Y clones proliferated faster and were more resistant to cytotoxic action of staurosporine, doxorubicin, irinotecan and cisplatin when compared to control cells. Moreover, these clones were characterized by a lower activity of caspases, calpains and some kinases (GSK-3ß, Akt and JNK). The mGluR8-downregulated LN229 clones migrated faster and were less prone to cell-damaging effect of staurosporine and irinotecan when compared with relevant control cells. In contrast, in GRM8-overexpressing U87-MG and LN18 clones, a decreased cell proliferation, increased apoptosis and elevated vulnerability to some cytotoxic agents were found. Altogether, our in vitro data for the first time evidenced a tumor suppressor and chemosensitizing role of mGluR8.

Bioassay-guided isolation of cytotoxic flavonoids from aerial parts of Coronopus didymus.

ETHNOPHARMACOLOGICAL RELEVANCE: Coronopus didymus Linn. (Brassicaceae) is a medicinal plant used traditionally as antipyretic, expectorant, to purify blood and for alleviating symptoms of pain, inflammations, malaria, wounds and cancer. AIM OF THE STUDY: The present study was designed to isolate and identify the cytotoxic compounds responsible for anticancer activity from this traditionally useful medicinal plant. MATERIALS AND METHODS: Bioassay-guided fractionation of the ethanolic extract of aerial parts of C. didymus allowed the isolation of compounds responsible for anticancer activity. Their structures were elucidated by UV Spectroscopy (with shift reagents), ESI-MS and NMR spectral data. Preliminary anticancer activity of ethanolic extract, different fractions and isolated compounds was assessed through MTT in vitro cytotoxicity assay in a dose dependent manner against human cancer cell lines (HeLa and LN18) and normal 293T cells. RESULTS: Three flavonoids namely 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-ß-D-glucoside (1), 5,7,4'-trihydroxy-3'-methoxyflavone-4'-O-(6''-acetyl)-ß-D-glucoside (2) and 5,7,4'-trihydroxy-3'-methoxy flavone (3), were isolated from aerial parts. Compound 1 was identified for the first time from the genus Coronopus. All the compounds 1-3 showed promising activity against HeLa cells with IC50 values of 43.50, 0.63 and 3.67 µM, respectively. Significant result was also obtained with compound 3 against LN18 cells with IC50 value of 46.63 µM. CONCLUSION: The cytotoxic activity of the crude extract and fractions which may largely be due to its major isolated constituents, flavonoids 1-3, against both HeLa and LN18 cells provides a scientific basis for the ethnopharmacological use of C. didymus as anticancer agent.

RNA interference mediated downregulation of human telomerase reverse transcriptase (hTERT) in LN18 cells.

Human telomerase reverse transcriptase (hTERT) gene is a biomarker for the targeted therapy in various cancers. Presence of increased telomerase activity is a common feature of all cancers including glioblastoma. Both RNA and catalytic subunits of hTERT are the target sites for blocking its activity. The current study focuses on the expression of hTERT in glioblastoma and its regulation using two different novel siRNAs (small interfering RNA). Our patient data demonstrated increased expression of hTERT, which could be correlated with carcinogenesis in glioma. In vitro studies in siRNA transfected LN18 cells confirmed significant cell death (p < 0.05) as evidenced by MTT and trypan blue exclusion assay. These results were further supported by flow cytometry data, which showed significant increase in early and late apoptosis. The hTERT mRNA expression was effectively downregulated by 45 and 39 % with siRNA1 and siRNA2, respectively. These results were further confirmed by immunoblotting analysis (p < 0.05). Our results suggest that both the siRNAs effectively down regulated the expression of hTERT at mRNA and protein levels, thereby decreasing cell viability and proliferation rate. Hence siRNA mediated downregulation of hTERT could be a potential therapeutic avenue in glioblastoma.

Celecoxib and LLW-3-6 Reduce Survival of Human Glioma Cells Independently and Synergistically with Sulfasalazine.

Gliomas are among the most commonly diagnosed central nervous system tumors. Celecoxib has been utilized with success in the treatment of several types of cancer, including gliomas. The present study examined the antiproliferative effects of celecoxib and its benzimidazole-based analog, LLW-3-6, when used as co-treatment with sulfasalazine against human glioma LN18 cells. At 48-h treatment, the glioma cells maintained 60% viability in the presence of celecoxib or LLW-3-6 at the maximum concentration tested (40 µM). Co-treatment of glioma cells under a non-lethal dose (50 µM) of sulfasalazine and either celecoxib or LLW-3-6 (administered at different concentrations) resulted in improved inhibition of cell viability. The concentration of the molecules required to reduce cell growth in the combined treatment was significantly less than that needed when either molecule was administered independently. Based on computational values, LLW-3-6 has physiochemical characteristics that should allow for improved bioavailability in comparison to that of celecoxib.