Corrigendum to "CXCR2-Expressing Tumor Cells Drive Vascular Mimicry in Antiangiogenic Therapy-Resistant Glioblastoma" Neoplasia, October 2018, Volume 20, Issue 10, Pages 1070-1082

Enhanced expression of pentraxin-3 in glioblastoma cells correlates with increased invasion and IL8-VEGF signaling axis

Glioblastoma (GB) is highly invasive and resistant to multimodal treatment partly due to distorted vasculature and exacerbated inflammation. The aggressiveness of brain tumors may be attributed to the dysregulated release of angiogenic and inflammatory factors. The glycoprotein pentraxin-3 (PTX3) is correlated with the severity of some cancers. However, the mechanism responsible for the invasive oncogenic role of PTX3 in GB malignancy remains unclear. In this study, we examined the role of PTX3 in GB growth, angiogenesis, and invasion using in vitro and in vivo GB models, proteomic profiling, molecular and biochemical approaches. Under in vitro conditions, PTX3 over-expression in U87 cells correlated with cell cycle progression, increased migratory potential, and proliferation under hypoxic conditions. Conditioned media containing PTX3 enhanced the angiogenic potential of endothelial cells. While silencing of PTX3 by siRNA decreased the proliferation, migration, and angiogenic potential of U87 cells in vitro. Importantly, PTX3 over-expression increased tumor growth, angiogenesis, and invasion in an orthotopic mouse model. Higher levels of PTX3 in these tumors were associated with the upregulation of inflammatory and angiogenic markers including interleukin-8 (IL-8) and vascular endothelial growth factor (VEGF), but decreased levels of thrombospondin-1, an anti-angiogenic factor. Mechanistically, exogenous production of PTX3 triggered an IKK/NFκB signaling pathway that enhances the expression of the motility genes AHGEF7 and Rac1. Taken together, PTX3 expression is dysregulated in GB. PTX3 may augment invasion through enhanced angiogenesis in the GB microenvironment through the IL8-VEGF axis. Thus, PTX3 may represent a potential therapeutic target to mitigate the aggressive behavior of gliomas.

[Mig-7 gene silencing inhibits vasculogenic mimicry formation and invasion of glioma U251 cells in vitro by suppressing MEK/ERK signaling]

OBJECTIVE

To investigate the inhibitory effects of silencing migration-inducing gene-7 (Mig-7) on vasculogenic mimicry formation, migration and invasion of human glioma cells in vitro and whether MEK/ERK signaling pathway mediates these effects.

METHODS

Human glioma U251 cells were infected by lentiviral vectors carrying a small interfering RNA targeting Mig-7 gene (sh-Mig-7) or a negative control shRNA (sh-NC), and real-time quantitative PCR was used to detect the expression level of Mig-7 mRNA in the cells. Three-dimensional culture and Transwell chamber invasion assay were used to observe the effect of Mig-7 gene silencing on vasculogenic mimicry formation and invasion ability of the U251 cells. Western blotting was performed to detect the changes in the protein expression levels of MEK/ERK in the infected cells.

RESULTS

We successfully obtained a U251 cell line with stable low expression of Mig-7 gene using RNA interference technique. Compared with the cells infected with sh-NC lentivirus and the non- infected cells, U251 cells infected with the lentiviral vector carrying sh-Mig-7 showed significantly decreased expression level of Mig-7 (P < 0.01) with obviously lowered vasculogenic mimicry formation and invasion abilities (P < 0.05). Mig-7 silencing also significantly lowered the expressions of MEK and ERK proteins in U251 cells (P < 0.05).

CONCLUSIONS

Silencing of Mig-7 gene inhibits vasculogenic mimicry formation and invasion of U251 cells possibly by suppressing MEK/ERK signaling, suggesting the important role of Mig-7 gene in vasculogenic mimicry formation and invasion of human glioma cells.