Project description:The Rad18 E3 ubiquitin ligase, a key regulator of DNA damage tolerance,also functions in repair of DNA double strand breaks. Rad18 is overexpressed in the brain cancer glioblastoma (GBM) and its downregulation sensitizes GBM cells to DNA damaging agents. Here we show that Rad18 has an essential role in GBM cells proliferation in the absence of external damage, surprisingly independent of its catalytic activity. Rad18 downregulation leads to cell cycle arrest in the G1 phase with no apparent increase in DNA damage. We also founbd that Rad18 sustains GBM stem cells self-renewal and survival, as well as the growth of GBM orthotropic xenografts in mice. We also show that increased Rad18 expression enhances the growth of non-transformed cells and induces features of oncogenic transformation. Mechanistically, we show that Rad18 downregulation negatively regulates the Hippo pathway by interfering with the nuclear retention of the YAP1 transcription factor. Altogether, these data show that Rad18 has an essential, non-catalytic function, in GBM proliferation, and propose Rad18 as a key target to sensitize GBM to therapy.
Project description:Brusatol (Bru), a Chinese herbal extract, has a variety of anti-tumor effects. However, little is known regarding its role and underlying mechanism in glioblastoma cells. Here, we found that Bru could inhibit the proliferation of glioblastoma cells in vivo and in vitro. Besides, it also had an inhibitory effect on human primary glioblastoma cells. In order to further study the underlying mechanism of Bru’s action on GBM, we performed RNA sequencing array on GBM cells treated by Bru with IC50 for 48 hours. A log2 fold change >1.0 and a P < 0.05 were used as cutoff criteria. The volcano plots results showed that Bru significantly changed the mRNA expression pattern in U251 (819 upregulated genes and 954 downregulated genes) and U87 (485 upregulated genes and 266 downregulated genes) cells. Then, we subjected these differentially expressed genes to the Reactome pathway database (https://reactome.org), which provides molecular details of signal transduction, transport, DNA replication, metabolism, and other cellular processes as an ordered network of molecular transformations in a single, consistent data model. Reactome enrichment analysis indicated that the collagen and extracellular matrix related pathways (Italic Script with *) were mainly involved in Bru-treated GBM cells. Subsequently, we used the Venn diagram analysis (VDA) to display the shared genes between U251 and U87 cells and finally determined that ESM1, an important factor in extracellular matrix formation, changed obviously by Bru treatment. Down-regulating the expression of ECM1 via transfecting siRNA could weaken the proliferation and invasion of glioblastoma cells and promote the inhibitory effect of Bru treatment. Lentivirus-mediated overexpression of ECM1 could effectively reverse this weakening effect. Our findings indicated that Bru could inhibit the proliferation and invasion of glioblastoma cells by suppressing the expression of ECM1, and Bru might be a novel effective anticancer drug for glioblastoma cells.
Project description:The invasion capacity is one of the hallmarks of glioblastoma (GBM) cells. We found that ODZ1 which is mainly expressed in fetal brain, plays a crucial role in the migration and proliferation of GBM stem-like cells (GSCs). Introduction of the entire ODZ1 or its intracellular fragment in ODZ1-deficient cells promotes migration and invasion in 2D and 3D substrates and in chicken embryo and mouse xenograft models. Moreover, ODZ1 increases the proliferation of GSCs in culture and generates bigger tumor masses in the brain of xenografted mice. Consistently, higher levels of ODZ1 are correlated with lower survival both in patients and in xenograft models. On note, ODZ1 promotes the transcriptional activation of RhoA and ODZ1-induced proliferation and invasion activities were blocked by inhibiting RhoA-ROCK axis. Overall, we describe a novel cancer-associated gene involved in the progression of glioblastoma, providing a putative prognostic marker and a new target for therapeutic strategies.
Project description:Glioblastoma (GBM) remains among the most lethal brain tumors despite improvements in treatment. Surgical resection is a universal component of glioma therapy. However, the mechanism underlying postoperative recurrence remains a challenge due to limited information regarding the changes that occur in the postoperative microenvironment. Here, we show that a subtype of proinflammatory reactive astrocytes designated is induced by inflammatory cytokines or injury. We show that reactive astrocytes can secrete the long noncoding RNA (lncRNA) LOC646762 to promotes recurrence glioblastoma proliferation in an exosome-dependent manner.We firstly named this reactive astrocyte associated lnRNA as “lnc-RVT1”.