Regulation of NRF2 by Phosphoinositides and Small Heat Shock Proteins.

Reactive oxygen species (ROS) are generated by aerobic metabolism, and their deleterious effects are buffered by the cellular antioxidant response, which prevents oxidative stress. The nuclear factor erythroid 2-related factor 2 (NRF2) is a master transcriptional regulator of the antioxidant response. Basal levels of NRF2 are kept low by ubiquitin-dependent degradation of NRF2 by E3 ligases, including the Kelch-like ECH-associated protein 1 (KEAP1). Here, we show that the stability and function of NRF2 is regulated by the type I phosphatidylinositol phosphate kinase g (PIPKIg), which binds NRF2 and transfers its product phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P 2 ) to NRF2. PtdIns(4,5)P 2 binding recruits the small heat shock protein HSP27 to the complex. Silencing PIPKIg or HSP27 destabilizes NRF2, reduces expression of its target gene HO-1, and sensitizes cells to oxidative stress. These data demonstrate an unexpected role of phosphoinositides and HSP27 in regulating NRF2 and point to PIPKIg and HSP27 as drug targets to destabilize NRF2 in cancer. In brief: Phosphoinositides are coupled to NRF2 by PIPKIγ, and HSP27 is recruited and stabilizes NRF2, promoting stress-resistance.

A p53-phosphoinositide signalosome regulates nuclear AKT activation.

The tumour suppressor p53 and PI3K-AKT pathways have fundamental roles in the regulation of cell growth and apoptosis, and are frequently mutated in cancer. Here, we show that genotoxic stress induces nuclear AKT activation through a p53-dependent mechanism that is distinct from the canonical membrane-localized PI3K-AKT pathway. Following genotoxic stress, a nuclear PI3K binds p53 in the non-membranous nucleoplasm to generate a complex of p53 and phosphatidylinositol 3,4,5-trisphosphate (PtdIns(3,4,5)P3), which recruits AKT, PDK1 and mTORC2 to activate AKT and phosphorylate FOXO proteins, thereby inhibiting DNA damage-induced apoptosis. Wild-type p53 activates nuclear AKT in an on/off fashion following stress, whereas mutant p53 dose-dependently stimulates high basal AKT activity. The p53-PtdIns(3,4,5)P3 complex is dephosphorylated to p53-phosphatidylinositol 4,5-bisphosphate by PTEN to inhibit AKT activation. The nuclear p53-phosphoinositide signalosome is distinct from the canonical membrane-localized pathway and insensitive to PI3K inhibitors currently in the clinic, which underscores its therapeutic relevance.

RNA-binding protein FXR1 drives cMYC translation by recruiting eIF4F complex to the translation start site.

Fragile X-related protein-1 (FXR1) gene is highly amplified in patients with ovarian cancer, and this amplification is associated with increased expression of both FXR1 mRNA and protein. FXR1 expression directly associates with the survival and proliferation of cancer cells. Surface sensing of translation (SUnSET) assay demonstrates that FXR1 enhances the overall translation in cancer cells. Reverse-phase protein array (RPPA) reveals that cMYC is the key target of FXR1. Mechanistically, FXR1 binds to the AU-rich elements (ARE) present within the 3' untranslated region (3'UTR) of cMYC and stabilizes its expression. In addition, the RGG domain in FXR1 interacts with eIF4A1 and eIF4E proteins. These two interactions of FXR1 result in the circularization of cMYC mRNA and facilitate the recruitment of eukaryotic translation initiation factors to the translation start site. In brief, we uncover a mechanism by which FXR1 promotes cMYC levels in cancer cells.

ERBB3-induced furin promotes the progression and metastasis of ovarian cancer via the IGF1R/STAT3 signaling axis.

High-grade serous carcinoma, accounts for up to 70% of all ovarian cases. Furin, a proprotein convertase, is highly expressed in high-grade serous carcinoma of ovarian cancer patients, and its expression is even higher in tumor omentum than in normal omentum, the preferred site of ovarian cancer metastasis. The proteolytic actions of this cellular endoprotease help the maturation of several important precursors of protein substrates and its levels increase the risk of several cancer. We show that furin activates the IGF1R/STAT3 signaling axis in ovarian cancer cells. Conversely, furin knockdown downregulated IGF1R-ß and p-STAT3 (Tyr705) expression. Further, silencing furin reduced tumor cell migration and invasion in vitro and tumor growth and metastasis in vivo. Collectively, our findings show that furin can be an effective therapeutic target for ovarian cancer prevention or treatment.

miRNA551b-3p Activates an Oncostatin Signaling Module for the Progression of Triple-Negative Breast Cancer.

Genomic amplification of 3q26.2 locus leads to the increased expression of microRNA 551b-3p (miR551b-3p) in triple-negative breast cancer (TNBC). Our results demonstrate that miR551b-3p translocates to the nucleus with the aid of importin-8 (IPO8) and activates STAT3 transcription. As a consequence, miR551b upregulates the expression of oncostatin M receptor (OSMR) and interleukin-31 receptor-α (IL-31RA) as well as their ligands OSM and IL-31 through STAT3 transcription. We defined this set of genes induced by miR551b-3p as the "oncostatin signaling module," which provides oncogenic addictions in cancer cells. Notably, OSM is highly expressed in TNBC, and the elevated expression of OSM associates with poor outcome in estrogen-receptor-negative breast cancer patients. Conversely, targeting miR551b with anti-miR551b-3p reduced the expression of the OSM signaling module and reduced tumor growth, as well as migration and invasion of breast cancer cells.

Isoliquiritigenin Inhibits Ovarian Cancer Metastasis by Reversing Epithelial-to-Mesenchymal Transition.

The epithelial-to-mesenchymal transition (EMT) plays a prominent role in cancer metastasis. Isoliquiritigenin (ISL), one of the flavonoids in licorice, has been shown to exhibit anticancer activities in many cancer types through various mechanisms. However, it is unknown whether ISL impacts the EMT process. Here, we show that ISL is able to suppress mesenchymal features of ovarian cancer SKOV3 and OVCAR5 cells, evidenced by an apparent morphological change from a mesenchymal to an epithelial phenotype and reduced levels of mesenchymal markers accompanied by the gain of E-cadherin expression. The suppression of EMT is also supported by the observed decrease in cell migration and in vitro invasion upon ISL treatment. Moreover, we show that ISL effectively blocks the intraperitoneal xenograft development of the SKOV3 cell line and prolonged the survival of tumor-bearing mice. These data suggest that ISL inhibits intraperitoneal ovary tumor development through the suppression of EMT, indicating that ISL may be an effective therapeutic agent against ovarian cancer.

B Cells as an Immune-Regulatory Signature in Ovarian Cancer.

Increasing evidence suggests that the immune system plays a dynamic role in the progression of ovarian cancer, the deadliest gynecological malignancy worldwide. Accumulation of tumor-infiltrating lymphocytes has been associated with increased survival in ovarian cancer patients, and diverse interactions among immune cells in the tumor microenvironment determine tumor progression. While the regulatory functions of T cells among tumor-infiltrating lymphocytes are well defined and also involve therapeutic interventions, the role of B cells in ovarian cancer progression is still limited to their impact on survival. Recent studies have identified both pro- and anti-tumor responses of B cells in solid tumors, as different subsets of B cells play diverse roles in progression. Thus, in-depth characterization of B cell subtypes in each disease stage is crucial for understanding the importance and therapeutic potential of these cells in ovarian cancer. In this review, we summarize current knowledge about B cells in ovarian cancer and discuss emerging therapeutic interventions that could harness B cells to combat this deadly disease.

Suppression of lung cancer progression by isoliquiritigenin through its metabolite 2, 4, 2', 4'-Tetrahydroxychalcone.

BACKGROUND: Licorice is an herb extensively used for both culinary and medicinal purposes. Various constituents of licorice have been shown to exhibit anti-tumorigenic effect in diverse cancer types. However, majority of these studies focus on the aspect of their growth-suppressive role. In this study, we systematically analyzed known licorice's constituents on the goal of identifying component(s) that can effectively suppress both cell migration and growth. METHODS: Effect of licorice's constituents on cell growth was evaluated by MTT assay while cell migration was assessed by both wound-healing and Transwell assays. Cytoskeleton reorganization and focal adhesion assembly were visualized by immunofluorescence staining with labeled phalloidin and anti-paxillin antibody. Activity of Src in cells was judged by western blot using phosphor-Src416 antibody while Src kinase activity was measured using Promega Src kinase assay system. Anti-tumorigenic capabilities of isoliquiritigenin (ISL) and 2, 4, 2', 4'-Tetrahydroxychalcone (THC) were investigated using lung cancer xenograft model. RESULTS: Using a panel of lung cancer cell lines, ISL was identified as the only licorice's constituent capable of inhibiting both cell migration and growth. ISL-led inhibition in cell migration resulted from impaired cytoskeleton reorganization and focal adhesion assembly. Assessing the phosphorylation of 141 cytoskeleton dynamics-associated proteins revealed that ISL reduced the abundance of Tyr421-phosphorylation of cortactin, Tyr925- and Tyr861-phosphorylation of FAK, indicating the involvement of Src because these sites are known to be phosphorylated by Src. Enigmatically, ISL inhibited Src in cells while displayed no effect on Src activity in cell-free system. The discrepancy was explained by the observation that THC, one of the major ISL metabolite identified in lung cancer cells abrogated Src activity both in cells and cell-free system. Similar to ISL, THC deterred cell migration and abolished cytoskeleton reorganization/focal adhesion assembly. Furthermore, we showed both ISL and THC suppressed in vitro lung cancer cell invasion and in vivo tumor progression. CONCLUSION: Our study suggests that ISL inhibits lung cancer cell migration and tumorigenesis by interfering with Src through its metabolite THC. As licorice is safely used for culinary purposes, our study suggests that ISL or THC may be safely used as a Src inhibitor.

Anti-inflammatory effects of 81 chinese herb extracts and their correlation with the characteristics of traditional chinese medicine.

Inducible nitrogen oxide synthase (iNOS) is the primary contributor of the overproduction of nitric oxide and its inhibitors have been actively sought as effective anti-inflammatory agents. In this study, we prepared 70% ethanol extracts from 81 Chinese herbs. These extracts were subsequently evaluated for their effect on nitrogen oxide (NO) production and cell growth in LPS/IFNγ-costimulated and unstimulated murine macrophage RAW264.7 cells by Griess reaction and MTT assay. Extracts of Daphne genkwa Sieb.et Zucc, Caesalpinia sappan L., Iles pubescens Hook.et Arn, Forsythia suspensa (Thunb.) Vahl, Zingiber officinale Rosc, Inula japonica Thunb., and Ligusticum chuanxiong Hort markedly inhibited NO production (inhibition > 90% at 100 µg/mL). Among active extracts (inhibition > 50% at 100 µg/mL), Rubia cordifolia L., Glycyrrhiza glabra L., Iles pubescens Hook.et Arn, Nigella glandulifera Freyn et Sint, Pueraria lobata (Willd.) Ohwi, and Scutellaria barbata D. Don displayed no cytotoxicity to unstimulated RAW246.7 cells while increasing the growth of LPS/IFNγ-costimulated cells. By analyzing the correlation between their activities and their Traditional Chinese Medicine (TCM) characteristics, herbs with pungent flavor displayed potent anti-inflammatory capability. Our study provides a series of potential anti-inflammatory herbs and suggests that herbs with pungent flavor are candidates of effective anti-inflammatory agents.

Alterations in TH- and ChAT-immunoreactive neurons in the DMV and gastric dysmotility in an LPS-induced PD rat model.

To study movement disorder in Parkinson's disease (PD), an animal model of PD can be created by injecting lipopolysaccharide (LPS) into the substantia nigra of rats. In addition to body movement disorders, patients with PD often experience gastrointestinal (GI) dysfunction, such as gastroparesis. However, the underlying mechanism of these disorders remains unclear. The dorsal motor nucleus of vagus (DMV) is a well-known visceral nucleus that regulates GI function. The present study investigated alterations in DMV neurons and gastric motility in rats with LPS-induced PD (LPS-PD rats). Gastric motility was recorded using a strain gauge force transducer in vivo. The distributions of tyrosine hydroxylase (TH)- and choline acetyltransferase (ChAT)-positive neurons in the DMV were determined using immunofluorescence and confocal laser microscopy. Our results indicated that in LPS-PD rats, the number of neurons in the substantia nigra, including neurons with TH immunoreactivity, was markedly reduced, although glial cell proliferation was clearly observed. However, enhanced TH immunoreactivity and decreased ChAT immunoreactivity were found in the DMV. Furthermore, weakened gastric motility was recorded in anesthetized LPS-PD rats. In conclusion, rats with LPS-induced PD exhibited gastric dysmotility with an alteration in DMV neurons. This PD model may be used to study autonomic nervous system disorders that are often observed in patients with early-stage PD.