Here we show that activation of the canonical WNT/β-catenin pathway increases the expression of stem cell genes and promotes the migratory and invasive capacity of glioblastoma. Modulation of WNT signaling alters the expression of epithelial-to-mesenchymal transition activators, suggesting a role of this process in the regulation of glioma motility. Using immunohistochemistry in patient-derived glioblastoma samples we showed higher numbers of cells with intranuclear signal for β-catenin in the infiltrating edge of tumor compared to central tumor parenchyma. These findings suggest that canonical WNT/β-catenin pathway is a critical regulator of GBM invasion and may represent a potential therapeutic target.

Circular RNAs (circRNAs) are reported to act as important regulators in cancers. CircRNA RAPGEF5 (cRAPGEF5) is derived from exons 2-6 of the RAPGEF5 gene and may promote papillary thyroid cancer progression. However, the role of cRAPGEF5 in renal cell carcinoma (RCC) remains unclear. In this study, we found cRAPGEF5 to be significantly downregulated in RCC tissues. Among 245 RCC cases, cRAPGEF5 downregulation correlated positively with aggressive clinical characteristics and independently predicted poor overall survival and recurrence-free survival. Functional assays demonstrated that cRAPGEF5 suppresses RCC proliferation and migration in vitro and in vivo. Mechanistically, RNA Immunoprecipitation and circRNA in vivo precipitation assays showed that cRAPGEF5 functions as a sponge of oncogenic miR-27a-3p, which targets the suppressor gene TXNIP. Interactions between miR-27a-3p and cRAPGEF5 or TXNIP were confirmed by dual-luciferase reporter assays. In conclusion, cRAPGEF5 plays a role in suppressing RCC via the miR-27a-3p/TXNIP pathway and may serve as a promising prognostic biomarker and novel therapeutic target for RCC patients.

Medulloblastoma is the most common malignant pediatric brain tumor. Tumors having high levels of c-MYC have the worst clinical prognosis, with only a minority of patients surviving. To address this unmet clinical need, we generated a human neural stem cell model of medulloblastoma that recapitulated the most aggressive subtype phenotypically and by mRNA expression profiling. An in silico analysis of these cells identified mTOR inhibitors as potential therapeutic agents. We hypothesized that the orally bioavailable TORC1/2 kinase inhibitor TAK228 would have activity against MYC-driven medulloblastoma. TAK228 inhibited mTORC1/2, decreased cell growth and caused apoptosis in high-MYC medulloblastoma cell lines. Comprehensive metabolic profiling of medulloblastoma orthotopic xenografts showed upregulation of glutathione compared to matched normal brain. TAK228 suppressed glutathione production. Because glutathione is required to detoxify platinum-containing chemotherapy, we hypothesized that TAK228 would cooperate with carboplatin in medulloblastoma. TAK228 synergized with carboplatin to inhibit cell growth and induce apoptosis and extended survival in orthotopic xenografts of high-MYC medulloblastoma. Brain-penetrant TORC1/2 inhibitors and carboplatin may be an effective combination therapy for high-risk medulloblastoma.

As a partner of tetraspanins, EWI2 suppresses glioblastoma, melanoma, and prostate cancer; but its role in lung cancer has not been investigated. Bioinformatics analysis reveals that EWI2 gene expression is up regulated in lung adenocarcinoma and higher expression of EWI2 mRNA may predict poorer overall survival. However, experimental analysis shows that EWI2 protein is actually downregulated constantly in the tissues of lung adenocarcinoma and lung squamous cell carcinoma. Forced expression of EWI2 in human lung adenocarcinoma cells reduces total cellular and cell surface levels of various integrins and growth factor receptors, which initiates the outside-in motogenic and mitogenic signaling. These reductions result in the decreases in 1) cell-matrix adhesion, cell movement, and cell transformation in vitro and 2) tumor growth, burden, and metastasis in vivo, and result from the increases in lysosomal trafficking and proteolytic degradation of theses membrane receptors. EWI2 elevates lysosome formation by promoting nuclear retention of TFEB, the master transcription factor driving lysosomogenesis. In conclusion, EWI2 as a lung cancer suppressor attenuates lung cancer cells in a comprehensive fashion by inhibiting both tumor growth and tumor metastasis; EWI2 as an endolysosome regulator promotes lysosome activity to enhance lysosomal degradation of growth factor receptors and integrins and then reduce their levels and functions; and EWI2 can become a promising therapeutic candidate given its accessibility at the cell surface, dual inhibition on growth factor receptors and integrins, and broad-spectrum anti-cancer activity. More importantly, our observations also provide a novel therapeutic strategy to bypass the resistance to EGFR inhibitors.

Tumor-associated microglia/macrophages (TAMs) are the main innate immune effector cells in malignant gliomas and have both pro- and anti-tumor functions. The plasticity of TAMs is partially dictated by oncogenic mutations in tumor cells. Heterozygous IDH1 mutation is a cancer driver gene prevalent in grade II/III gliomas, and IDH1 mutant gliomas have relatively favorable clinical outcomes. It is largely unknown how IDH mutation alters TAM phenotypes to influence glioma growth. Here we established clinically relevant isogenic glioma models carrying monoallelic IDH1 R132H mutation (IDH1R132H/WT) and found that IDH1R132H/WT significantly downregulated immune response-related pathways in glioma cells, indicating an immunomodulation role of mutant IDH1. Co-culturing IDH1R132H/WT glioma cells with human macrophages promoted anti-tumor phenotypes of macrophages and increased macrophage migration and phagocytic capacity. In orthotopic xenografts, IDH1R132H/WT decreased tumor growth and prolonged animal survival, accompanied by increased TAM recruitment and upregulated phagocytosis markers, suggesting the induction of anti-tumor TAM functions. Using human cytokine arrays that query 36 proteins, we identified significant downregulation of ICAM-1/CD54 in IDH1R132H/WT gliomas, which was further confirmed by ELISA and immunoblotting analyses. ICAM1 gain-of-function studies revealed that ICAM1 downregulation in IDH1R132H/WT cells played a mechanistic role to mediate the immunomodulation function of IDH1R132H/WT. ICAM-1 silencing in IDH1 wild-type glioma cells decreased tumor growth and increased the anti-tumor function of TAMs. Together, our studies support a new TAM-mediated phagocytic function within IDH1 mutant gliomas, and improved understanding of this process may uncover novel approaches to targeting IDH1 wild type gliomas.

TGF-β plays a central role in prostate cancer (PCa) bone metastasis, and it is crucial to understand the bone cell-specific role of TGF-β signaling in this process. Thus, we used knockout (KO) mouse models having deletion of the Tgfbr2 gene specifically in osteoblasts (Tgfbr2Col1CreERT KO) or in osteoclasts (Tgfbr2LysMCre KO). We found that PCa-induced bone lesion development was promoted in the Tgfbr2Col1CreERT KO mice, but was inhibited in the Tgfbr2LysMCre KO mice, relative to their respective control Tgfbr2FloxE2 littermates. Since metastatic PCa cells attach to osteoblasts when colonized in the bone microenvironment, we focused on the mechanistic studies using the Tgfbr2Col1CreERT KO mouse model. We found that bFGF was upregulated in osteoblasts from PC3-injected tibiae of Tgfbr2Col1CreERT KO mice and correlated with increased tumor cell proliferation, angiogenesis, amounts of cancer-associated fibroblasts and osteoclasts. In vitro studies showed that osteoblastogenesis was inhibited, osteoclastogenesis was stimulated, but PC3 viability was not affected, by bFGF treatments. Lastly, the increased PC3-induced bone lesions in Tgfbr2Col1CreERT KO mice were significantly attenuated by blocking bFGF using neutralizing antibody, suggesting bFGF is a promising target inhibiting bone metastasis.

Non-small cell lung cancer (NSCLC) accounts for more than 85% of lung cancer with high incidence and mortality. Accumulating studies have shown that traditional Chinese medicine (TCM) and its active ingredients have good anti-tumor activity. However, the anti-tumor effect of Thevebioside (THB), an active ingredient from TCM, is still unknown in NSCLC. In this study, to our best knowledge, it was the first time to report the underlying mechanism of its tumor-suppressive activity in NSCLC based on our previous high-throughput screening data. We further demonstrated that THB effectively inhibited the proliferation of NSCLC cells (A549 and H460) by inducing cellular apoptosis rather than cell cycle arrest. Notably, it was demonstrated that SRC-3 was significantly down-regulated after THB treatment dependent on ubiquitin-proteasome-mediated degradation, which subsequently inhibited the IGF-1R-PI3K-AKT signaling pathway and promoted apoptosis via both in vivo and in vitro experiments. Collectively, THB exerted inhibitory effect on tumor growth of NSCLC through inhibiting SRC-3 mediated IGF-1R-PI3K-AKT signaling by ubiquitination to induce cellular apoptosis with minimal toxicity no matter in vitro or vivo.