Combined temozolomide and ionizing radiation induces galectin-1 and galectin-3 expression in a model of human glioma

Background Despite aggressive treatment for glioblastoma multiforme (GBM), including surgical resection, radiotherapy and temozolomide (TMZ) chemotherapy, over 90% of patients experience tumor recurrence. Galectins are carbohydrate-binding proteins that are overexpressed in the stroma of GBM tumors, and are potent modulators of GBM cell migration and angiogenesis. The objective of this study was to analyze glioma and endothelial cell galectin expression in response to combined chemoradiation. Methodology The effects of TMZ, ionizing radiation, or combined chemoradiation on galectin protein secretion and expression were assessed in U87 orthotopically grown GBM tumors in mice, as well as in vitro in U87 human glioma cells and human umbilical vein endothelial cells (HUVECs). Results We found that combination chemoradiation increased galectin-1 and galectin-3 protein expression in U87 glioma cells. In response to radiation alone, U87 cells secreted significant levels of galectin-1 and galectin-3 into the microenvironment. HUVEC co-culture increased U87 galectin-1 and galectin-3 protein expression 14 - 20% following chemoradiation, and conferred a radioprotective benefit to U87 glioma cells. In vivo, radiation alone and combination chemoradiation significantly increased tumor galectin-1 expression in an orthotopic murine model of GBM. Conclusions Glioma cell galectin expression increased following combined chemoradiation, both in vitro and in vivo. The presence of endothelial cells further increased glioma cell galectin expression and survival, suggesting that crosstalk between tumor and endothelial cells in response to standard chemoradiation may be an important factor in mediating glioma recurrence, potentially via galectin upregulation.

A Positive Prospective Trial of Antibiotic Therapy in Advanced Stage, Non-Bulky Indolent Lymphoma

Background: We have prospectively studied a three month course of clarithromycin (substituted by Prevpac®, lansoprazole/ amoxicillin/ clarithromycin, in the first two wks when stool H pylori+) for non-bulky, advanced stage indolent lymphoma. These patients are often candidates for expectant monitoring and it is during this period that a window of opportunity may exist to identify and treat associated infections. Methods: All previously untreated patients with a new diagnosis of indolent lymphoma (FL and non-FL) meeting GELF criteria were treated with 12 weeks of clarithromycin. There were 32 evaluable patients, 4 of whom had stool H pylori. Results: At one month post-antibiotic therapy, we have observed lymphoma responses in 7 of 32 patients (21.9%). Two additional patients had objective response during followup (28.1% overall response). The median treatment free survival for antibiotic responders is 69.9 months and for non-responders, 30.6 months (p = 0.019). Conclusion: Three response patterns have been noted, perhaps suggestive of an immune-mediated response -- prompt PET negative; flair with delayed PET negative response; and gradual continuous improvement. This prospective study appears promising, may be a step toward developing a lymphoma prevention strategy by reducing “antigen drive,” and deserves further clinical/biological study. http://clinicaltrials.gov/show/NCT00461084

MicroRNA-21 inhibitor potentiates anti-tumor effect of radiation therapy in vitro and in vivo

MicroRNA-21 (miR-21) plays important roles in carcinogenesis and is highly expressed in diverse human cancers. We evaluated the potential of targeting miRNA-21 to overcome the radioresistance of human cancer cells having an activated EGFR2-associated signaling and also aimed to elucidate the mechanisms of radiosensitization, and the effect on epithelial- mesenchymal transition (EMT). Ectopic overexpression of miR-21 up-regulated EGFR/HER2-associated signaling and increased radioresistance of a panel of human cancer cells (U251, U87, and A549 cells). In contrast, a specific inhibitor of miR-21 attenuated this signaling and radiosensitized a panel of human cancer cells. Inhibition of miR-21 was associated with persistent γH2AX foci formation. Inhibition of miR-21 decreased the typical features of EMT, such as invasion and migration and vascular tube formation. Treatment with anti-miR-21 decreased tumor burden in nude mice bearing intracranial U251 xenografts compared to controls. Combined treatment of anti-miR-21 and radiation further decreased tumor burden compared to each treatment alone. In summary, miR-21 is an important onco-miR, which confers radioresistance and diverse features of EMT. Inhibition of miR-21 could be a potential strategy for improving the efficacy of radiation therapy via unique modulation of pro-survival signaling implicated in radiation response and EMT.