GM-CSF induces proinflammatory macrophages, but the underlying mechanisms have not been studied thus far. In this study, we investigated the mechanisms of how GM-CSF induces inflammatory macrophages. First, we observed that GM-CSF increased the extent of LPS-induced acute glycolysis in murine bone marrow-derived macrophages. This directly correlates with an inflammatory phenotype because glycolysis inhibition by 2-deoxyglucose abolished GM-CSF-mediated increase of TNF-α, IL-1β, IL-6, and IL-12p70 synthesis upon LPS stimulation. Increased glycolytic capacity is due to de novo synthesis of glucose transporter (GLUT)-1, -3, and -4, as well as c-myc. Meanwhile, GM-CSF increased 3-hydroxy-3-methyl-glutaryl-CoA reductase, which is the rate-limiting enzyme of the mevalonate pathway. Inhibition of acute glycolysis or 3-hydroxy-3-methyl-glutaryl-CoA reductase abrogated the inflammatory effects of GM-CSF priming in macrophages. Finally, mice with inflamed colons exposed to dextran sodium sulfate containing GLUT-1 macrophages led to massive uptake of [F]-fluorodeoxyglucose, but GM-CSF neutralization reduced the positron-emission tomography signal in the intestine and also decreased GLUT-1 expression in colonic macrophages. Collectively, our results reveal glycolysis and lipid metabolism created by GM-CSF as the underlying metabolic constructs for the function of inflammatory macrophages.

Tumor metastasis involves circulating and tumor-initiating capacities of metastatic cancer cells. Epithelial-mesenchymal transition (EMT) is related to self-renewal capacity and circulating tumor cell (CTC) characteristics for tumor metastasis. Although tumor metastasis is a life-threatening, complicated process that occurs through circulation of tumor cells, mechanistic aspects of self-renewal and circulating capacities have been largely unknown. Hepatic transmembrane 4 L six family member 5 (TM4SF5) promotes EMT for malignant growth and migration, so it was rationalized that TM4SF5, as a hepatocellular carcinoma (HCC) biomarker, might be important for metastatic potential. Here, self-renewal capacity by TM4SF5 was mechanistically explored using hepatocarcinoma cells with or without TM4SF5 expression, and we explored whether they became CTCs using mouse liverorthotopic model systems. We found that TM4SF5-dependent sphere growth correlated with CD242 , aldehyde dehydrogenase (ALDH) activity, as well as a physical association between CD44 and TM4SF5. Interaction between TM4SF5 and CD44 was through their extracellular domains with N-glycosylation modifications. TM4SF5/CD44 interaction activated proto-oncogene tyrosine-protein kinase Src (c-Src)/signal transducer and activator of transcription 3 (STAT3)/Twist-related protein 1 (Twist1)/B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) signaling for spheroid formation, whereas disturbing the interaction, expression, or activity of any component in this signaling pathway inhibited spheroid formation. In serial xenografts using 2005,000 cells per injection, TM4SF5-positive tumors exhibited subpopulations with locally increased CD44 expressions, supporting for tumor cell differentiation. TM4SF5-positive, but not TM4SF5-or CD44-knocked-down, cells were identified circulating in blood 4-6 weeks after orthotopic liver injection using in vivo laser scanning endomicroscopy. Anti-TM4SF5 reagent blocked their metastasis to distal intestinal organs. Conclusion: TM4SF5 promotes self-renewal and CTC properties supported by TM4SF5 1 /CD442 markers during HCC metastasis. (HEPATOLOGY 2015;61:1978-1997 H epatocellular carcinoma (HCC) is the thirdmost common cause of mortality resulting from cancer.1 Although hepatic resection and liver transplantation represent first-line treatments for HCC, 2 the second-line treatment for HCC patients in advanced stages has shown limited efficacy.3 Moreover, metastatic recurrence renders this carcinoma resistant to any significant chemopreventive effects.

This study aimed to examine whether inhibition of hexokinase (HK)-II activity enhances the efficacy of sorafenib in in-vivo models of hepatocellular carcinoma (HCC), and to evaluate the prognostic implication of HK-II expression in patients with HCC. We used 3-bromopyruvate (3-BP), a HK-II inhibitor to target HK-II. The human HCC cell line was tested as both subcutaneous and orthotopic tumor xenograft models in BALB/c nu/nu mice. The prognostic role of HK-II was evaluated in data from HCC patients in The Cancer Genome Atlas (TCGA) database and validated in patients treated with sorafenib. Quantitative real-time PCR, western blot analysis, and immunohistochemical staining revealed that HK-II expression is upregulated in the presence of sorafenib. Further analysis of the endoplasmic reticulum-stress network model in two different murine HCC models showed that the introduction of additional stress by 3-BP treatment synergistically increased the in vivo/vitro efficacy of sorafenib. We found that HCC patients with increased HK-II expression in the TCGA database showed poor overall survival, and also confirmed similar results for TCGA database HCC patients who had undergone sorafenib treatment. These results suggest that HK-II is a promising therapeutic target to enhance the efficacy of sorafenib and that HK-II expression might be a prognostic factor in HCC.

Radiotherapy treats cancer by inducing DNA double-strand breaks (DSB) in tumor cells using ionizing radiation. However, DNA repair in tumor cells often leads to radioresistance and unsuccessful outcome. Inhibition of DNA repair by targeting repair proteins can increase radiosensitivity of tumor cells. The BRG1 chromatin remodeling enzyme assists DSB repair by stimulating g-H2AX formation and BRG1 binding to acetylated histones at DSBs via bromodomain (BRD) is critical for this activity. Here, we show that ectopic expression of BRG1-BRD inhibited g-H2AX and DSB repair after irradiation and increased the radiosensitivity in various human cancer cells, including HT29 colon cancer. Dimerization of BRG1-BRD, increasing its chromatin binding affinity, aggravated the defects in g-H2AX and DSB repair and further enhanced the radiosensitivity. While little affecting the upstream ATM activation, BRG1-BRD in irradiated HT29 cells inhibited the recruitment of 53BP1 to damaged chromatin, the downstream event of g-H2AX, and compromised the G 2 -M checkpoint and increased apoptosis. Importantly, in a xenograft mouse model, BRG1-BRD increased the radiosensitivity of HT29 tumors, which was further enhanced by dimerization. These data suggest that BRG1-BRD radiosensitizes tumor cells by a dominant negative activity against BRG1, which disrupts g-H2AX and its downstream 53BP1 pathways, leading to inefficient DNA repair, G 2 -M checkpoint defect, and increased apoptosis. This work therefore identifies BRG1-BRD as a novel tumor radiosensitizer and its action mechanism, providing the first example of chromatin remodeler as a target for improving cancer radiotherapy.

We investigated a therapeutic strategy for recurrent malignant gliomas using mesenchymal stem cells (MSC), expressing cytosine deaminase (CD), and prodrug 5-Fluorocytosine (5-FC) as a more specific and less toxic option. MSCs are emerging as a novel cell therapeutic agent with a cancer-targeting property, and CD is considered a promising enzyme in cancer gene therapy which can convert non-toxic 5-FC to toxic 5-Fluorouracil (5-FU). Therefore, use of prodrug 5-FC can minimize normal cell toxicity. Analyses of microarrays revealed that targeting DNA damage and its repair is a selectable option for gliomas after the standard chemo/radio-therapy. 5-FU is the most frequently used anti-cancer drug, which induces DNA breaks. Because dihydropyrimidine dehydrogenase (DPD) was reported to be involved in 5-FU metabolism to block DNA damage, we compared the survival rate with 5-FU treatment and the level of DPD expression in 15 different glioma cell lines. DPD-deficient cells showed higher sensitivity to 5-FU, and the regulation of DPD level by either siRNA or overexpression was directly related to the 5-FU sensitivity. For MSC/CD with 5-FC therapy, DPD-deficient cells such as U87MG, GBM28, and GBM37 showed higher sensitivity compared to DPD-high U373 cells. Effective inhibition of tumor growth was also observed in an orthotopic mouse model using DPD- deficient U87MG, indicating that DPD gene expression is indeed closely related to the efficacy of MSC/CD-mediated 5-FC therapy. Our results suggested that DPD can be used as a biomarker for selecting glioma patients who may possibly benefit from this therapy.