Hypoxia-driven changes in the tumor microenvironment facilitate cancer metastasis. In the present study, we investigated the regulatory cross talk between endocytic pathway, hypoxia, and tumor metastasis. Dynamin 2 (DNM2), a GTPase, is a critical mediator of endocytosis. Hypoxia decreased the levels of DNM2. DNM2 promoter has multiple hypoxia-inducible factor (HIF)-binding sites and genetic deletion of them relieved hypoxia-induced transcriptional suppression. Interestingly, DNM2 reciprocally regulated HIF. Inhibition of DNM2 GTPase activity and dominantnegative mutant of DNM2 showed a functional role for DNM2 in regulating HIF. Furthermore, the opposite strand of DNM2 gene encodes miR-199a, which is similarly reduced in cancer cells under hypoxia. miR-199a targets the 3′-UTR of HIF-1α and HIF-2α. Decreased miR-199a expression in hypoxia increased HIF levels. Exogenous expression of miR-199a decreased HIF, cell migration, and metastasis of ovarian cancer cells. miR-199a-mediated changes in HIF levels affected expression of the matrix-remodeling enzyme, lysyloxidase (LOX). LOX levels negatively correlated with progression-free survival in ovarian cancer patients. These results demonstrate a regulatory relationship between DNM2, miR199a, and HIF, with implications in cancer metastasis.microRNA | iron regulation E pithelial ovarian cancer (EOC) is the leading cause of death among the gynecological malignancies (1). Ascites development and peritoneal metastasis are unique features of ovarian cancer progression. Gas analyses of ovarian cancer ascites show about 2.5% dissolved oxygen content, whereas the blood oxygen content ranges between 15% and 23% (2). Hypoxic areas are common in tumor microenvironment as increased metabolic demands of rapidly proliferating cells outpace oxygen availability. Sustained exposure to hypoxia spurs cells to reorganize cellular processes, and energy-consuming functions, such as endocytosis, are suppressed (3, 4). Hypoxia-inducible factor-1α and hypoxia-inducible factor-2α (HIF-1α/HIF-2α) are principal coordinators of these responses. HIF-1α/HIF-2α are stabilized in hypoxia and associate with hypoxia-inducible factor-1β (HIF-1β) to form heterodimeric transcription factors and induce the expression of target genes (5, 6). HIF-1-mediated expression of lysyloxidase (LOX) cross-links collagens and induces cell migration (7). Epithelial ovarian cancer cells (EOCCs) that have adapted to hypoxia by activating HIF-1 disseminate from primary ovarian tumors and exfoliate into the peritoneal cavity. HIF-1 significantly enhances gene signatures associated with tissue remodeling, the morbidity and mortality associated with EOC (8, 9).Regulation of HIF-1 is a key step in the hypoxic response with profound implications for EOC metastasis. Under normoxia, HIF-1α is hydroxylated within its oxygen-dependent degradation domain (ODDD) by prolylhydroxylases (PHDs). This reaction is an oxygen-, iron-, 2-oxoglutarate and ascorbate-dependent process. Hydroxylated HIF-1α is recognized and bound by a complex that...
Non-coding RNAs are functional RNA molecules comprising the majority of human transcriptome. Only about 1.5% of the human genome is transcribed into messenger RNAs (mRNA) that are translated into proteins. Among the non-coding RNAs, miRNAs are extensively studied and miR targets in endothelial cells, perivascular cells, and angiogenic signaling are relatively well defined. MicroRNAs not only regulate transcripts in situ but also function as paracrine mediators in affecting angiogenesis at distant sites. Exosomal miRs are implicated in modulating endothelial cell function and angiogenesis. Thus miRs have been shown to affect tissue microenvironment in a multitude of ways. A comprehensive analysis of the role of miRs in modulation of angiogenesis and their impact on cardiovascular diseases is presented in this review.
The nucleoside analog 5,6-dihydro-5-aza-2’-deoxycytidine (KP-1212) has been investigated as a first-in-class lethal mutagen of human immunodeficiency virus type-1 (HIV-1). Since a prodrug monotherapy did not reduce viral loads in Phase II clinical trials, we tested if ribonucleotide reductase inhibitors (RNRIs) combined with KP-1212 would improve antiviral activity. KP-1212 potentiated the activity of gemcitabine and resveratrol and simultaneously increased the viral mutant frequency. G-to-C mutations predominated with the KP-1212-resveratrol combination. These observations represent the first demonstration of a mild anti-HIV-1 mutagen potentiating the antiretroviral activity of RNRIs and encourage the clinical translation of enhanced viral mutagenesis in treating HIV-1 infection.
Objective Minnelide is a water-soluble pro-drug of triptolide, a natural product. The goal of this study was to evaluate the effectiveness of Minnelide on ovarian cancer growth in vitro and in vivo. Methods The effect of Minnelide on ovarian cancer cell proliferation was determined by real time electrical impedance measurements. Multiple mouse models with C200 and A2780 epithelial ovarian cancer cell lines were used to assess the efficacy of Minnelide in inhibiting ovarian cancer growth. Results Minnelide decreased cell viability of both platinum sensitive and resistant epithelial ovarian cancer cells in vitro. Minnelide with carboplatin showed additive effects in vitro. Minnelide monotherapy increased the survival of mice bearing established ovarian tumors. Minnelide, in combination with carboplatin and paclitaxel, improved overall survival of mice. Conclusions Minnelide is a promising pro-drug for the treatment of ovarian cancer, especially when combined with standard chemotherapy.
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