Xiangqi Meng

<h3>Objective:</h3> Neutrophil extracellular traps (NETs) produced by tumor-infiltrating neutrophils (TINs) are associated with poor prognosis in patients with several types of cancer. However, the mechanisms underlying the involvement of NETs in glioma progression remain largely unknown. This study aimed to elucidate the roles of NETs in biological processes that drive the crosstalk between glioma progression and the tumor microenvironment. <h3>Methods:</h3> Neutrophil infiltration and NETs formation were investigated in glioma tissue through immunohistochemistry, and their relationships with clinicopathological features and outcomes were statistically evaluated. The effects of NETs on glioma cell progression were studied in a co-culture system. <i>In vivo</i> and <i>in vitro</i> experiments validated the reactive oxygen species activity and cytokine production of TINs, as well as the ERK signaling pathway activation and the metastasis of gliomas. <h3>Results:</h3> Neutrophil infiltration and NETs formation were induced in high-grade glioma compared with low-grade glioma. NETs induced by TINs were determined to be an oncogenic marker of high-grade gliomas and to be involved in cell proliferation and invasion. NETs overproduction promoted glioma cell proliferation, migration, and invasion. Furthermore, HMGB1 was found to bind to RAGE and activate the NF-κB signaling pathway <i>in vitro</i>. In addition, NETs stimulated the NF-κB signaling pathway, thus promoting IL-8 secretion in glioblastoma. Subsequently, IL-8 recruited neutrophils which in turn mediated NETs formation <i>via</i> the PI3K/AKT/ROS axis in TINs. <h3>Conclusions:</h3> Our results suggest that NETs produced by TINs mediate the crosstalk between glioma progression and the tumor microenvironment by regulating the HMGB1/RAGE/IL-8 axis. Targeting NETs formation or IL-8 secretion may be an effective approach to inhibit glioma progression.

Long noncoding RNAs (lncRNAs) have emerged as new regulatory molecules implicated in diverse biological processes, including therapeutic resistance. However, the mechanisms underlying lncRNA-mediated temozolomide (TMZ) resistance in glioblastoma (GBM) remain largely unknown. To illustrate the role of lncRNA in TMZ resistance, we induce TMZ-resistant GBM cells, perform a lncRNA microarray of the parental and TMZ-resistant cells, and find an unreported lncRNA in GBM, lnc-TALC (temozolomide-associated lncRNA in glioblastoma recurrence), correlated with TMZ resistance via competitively binding miR-20b-3p to facilitate c-Met expression. A phosphorylated AKT/FOXO3 axis regulated lnc-TALC expression in TMZ-resistant GBM cells. Furthermore, lnc-TALC increased MGMT expression by mediating the acetylation of H3K9, H3K27 and H3K36 in MGMT promoter regions through the c-Met/Stat3/p300 axis. In clinical patients, lnc-TALC is required for TMZ resistance and GBM recurrence. Our results reveal that lnc-TALC in GBM could serve as a therapeutic target to overcome TMZ resistance, enhancing the clinical benefits of TMZ chemotherapy.

Overexpressed DNA methyltransferase 1 (DNMT1) strongly contributes to tumor suppressor gene silencing in colorectal cancer (CRC). However, the underlying mechanism of DNMT1 overexpression is still unclear. MicroRNAs (miRNA) have been implicated as gene regulators controlling diverse biological processes, including carcinogenesis. In this study, we investigated whether some miRNA is involved in the regulation of DNMT1 and thus play a functional role in CRC. Our results showed that miR-342 was downregulated in CRC tissues and cell lines. Restoration of miR-342 resulted in a dramatic reduction of the expression of DNMT1 at both messenger RNA and protein levels by directly targeting its 3' untranslated region. This in turn reactivated ADAM23, Hint1, RASSF1A and RECK genes via promoter demethylation. Furthermore, the enhanced expression of miR-342 could significantly inhibit SW480 cell proliferation in vitro (P = 0.006). Further investigation demonstrated G(0)/G(1) cell cycle arrest in SW480 cells, which was associated with an upregulation of p21 and downregulation of cyclinE and CDK2. Overexpression of miR-342 also inhibited SW480 cell invasion. The in vivo antitumor effect was evaluated in SW480 cells with lentivirus-mediated expression of miR-342. Results showed that overexpression of miR-342 significantly inhibited tumor growth and lung metastasis in nude mice (P = 0.034). Our findings describe a new mechanism for the regulation of DNMT1 and aberrant DNA hypermethylation in CRC. This is also the first report to demonstrate that miR-342 may act as a tumor suppressor gene in CRC development. The newly identified miR-342/DNMT1 link provides a new, potential therapeutic target for the treatment of CRC.

Abstract Activation of receptor tyrosine kinase (RTK) protein is frequently observed in malignant progression of gliomas. In this study, the crosstalk activation of epidermal growth factor receptor (EGFR) and mesenchymal-epithelial transition factor (MET) signaling pathways is demonstrated to contribute to temozolomide (TMZ) resistance, resulting in an unfavorable prognosis for patients with glioblastoma. To simultaneously mitigate EGFR and MET activation, a dual functionalized brain-targeting nanoinhibitor, BIP-MPC-NP, is developed by conjugating Inherbin3 and cMBP on the surface of NHS-PEG 8 -Mal modified MPC-nanoparticles. In the presence of BIP-MPC-NP, DNA damage repair is attenuated and TMZ sensitivity is enhanced via the down-regulation of E2F1 mediated by TTP in TMZ resistant glioma. In vivo magnetic resonance imaging (MRI) shows a significant repression in tumor growth and a prolonged survival of mice after injection of the BIP-MPC-NP and TMZ. These results demonstrate the promise of this nanoinhibitor as a feasible strategy overcoming TMZ resistance in glioma.

PURPOSE: Sirtuins play an important role in cancer development. Sirt7, as a member of this family, is frequently overexpressed in certain carcinomas, but the oncogenic mechanism is seldom reported. In this study, Sirt7 was characterized for its role in colorectal cancer aggressiveness and underlying molecular mechanisms. EXPERIMENTAL DESIGN: Quantitative PCR, Western blotting, and immunohistochemistry were performed to study Sirt7 expression in a cohort of colorectal cancer tissues and non-tumor tissues and cells. A series of in vitro and in vivo assays was performed to elucidate the function of Sirt7 in colorectal cancer and its underlying mechanisms. Association between the Sirt7 signature and survival was examined using Kaplan-Meier analysis and log-rank tests. RESULTS: The Sirt7 protein level significantly correlated with tumor stage (P = 0.029), lymph node metastasis (P = 0.046), and poor patient survival (P < 0.05). Sirt7 knockdown significantly inhibited colorectal cancer cell proliferation, colony formation, and motility. Ectopic Sirt7 expression promoted colony formation, induced a more invasive phenotype, and accelerated cell growth both in vitro and in vivo. Moreover, Sirt7 enhanced MAPK pathway activity concomitantly with p-ERK and p-MEK upregulation. In Sirt7-overexpressing cells, the mesenchymal markers vimentin and fibronectin were upregulated, and the epithelial markers E-cadherin and β-catenin were downregulated, which was linked to enhanced invasion by colorectal cancer cells. CONCLUSION: Our findings suggest that Sirt7 plays an important role in the development and progression of human colorectal cancer and functions as a valuable marker of colorectal cancer prognosis.