The mineral dust-induced gene, mdig, regulates angiogenesis and lymphangiogenesis in lung adenocarcinoma by modulating the expression of VEGF-A/C/D via EGFR and HIF-1α signaling

Abstract

Mineral dust-induced gene (mdig) is a novel lung cancer-related oncogene. The aim of this study was to explore the effects of mdig on angiogenesis and lymphangiogenesis by vascular endothelial growth factor (VEGF) in lung adenocarcinoma. mdig-overexpressing A549, H1299 and 293T cells, mdig-silenced A549, human umbilical vein endothelial cells (HUVECs) and human lymphatic endothelial cells (HLECs) were cultured under normoxic and hypoxic conditions. Protein expression levels of mdig, epidermal growth factor receptor (EGFR), phospho(p)-EGFR Tyr1068, hypoxia-inducible factor-1α (HIF-1α), VEGF-A/C/D and VEGF-R1/R2/R3 were assessed using western blotting. mRNA expression levels of mdig, EGFR and HIF-1α were measured using RT-qPCR. Tube formation and xenograft tumor experiments were performed to examine the mechanism of mdig in angiogenesis and lymphangiogenesis. Protein expression levels of EGFR, HIF-1α and VEGF-A/C/D were significantly upregulated in cells cultured under hypoxic conditions compared with those cultured under normoxic conditions, whereas the levels of mdig were decreased. Protein expression levels of EGFR, p-EGFR and VEGF-A/R1/R2 were significantly increased in the mdig-overexpressing cells, whereas the levels of HIF-1α and VEGF-C/D/R3 were decreased compared with those in control cells, all of which were reversed in mdig-silenced cells. Tumor volumes and density of angiogenesis in the mdig-overexpressing group were significantly increased compared with those in the control group, whereas the density of lymphangiogenesis was decreased. No tumors formed in the mdig-silenced group after 3 weeks of assessment in vivo. Protein expression levels of EGFR, p-EGFR, VEGF-A and angiogenesis density were significantly reduced in the mdig-overexpressing cells treated with an EGFR inhibitor, whereas the levels of HIF-1α, VEGF-C/D and the lymphangiogenesis density were significantly increased in mdig-overexpressing cells treated with a HIF-1α agonist. All changes in protein expression were reversed in EGFR agonist and HIF-1α inhibitor treated mdig-silenced cells. In conclusion, mdig is an oxygen-sensitive protein that promotes tumor growth and angiogenesis by activating the EGFR/p-EGFR/VEGF-A/VEGF-R1/R2 pathway and inhibits lymphangiogenesis by blocking the HIF-1α/VEGF-C/D/VEGF-R3 pathway.

Afatinib in Untreated Stage IIIB/IV Lung Adenocarcinoma with Major Uncommon Epidermal Growth Factor Receptor (EGFR) Mutations (G719X/L861Q/S768I): A Multicenter Observational Study in Taiwan

“…The EGFR protein consists of an extracellular ligand-binding receptor, a transmembrane domain, and an intracellular tyrosine kinase domain. When mutations occur in exons 18-21, which encode the tyrosine kinase domain, the kinase activity of EGFR increases and activates downstream pro-survival signaling pathways in NSCLC [1][2][3]. EGFR mutations are the most frequent oncogenic driver mutations in East Asian lung adenocarcinoma patients (ranging from 45 to 55%) [3,4].…”

“…The epidermal growth factor receptor (EGFR) signaling pathway plays a crucial role in promoting the pathogenesis of human non-small-cell lung cancer (NSCLC) [ 1 , 2 ]. The EGFR protein consists of an extracellular ligand-binding receptor, a transmembrane domain, and an intracellular tyrosine kinase domain.…”

MDIG, a 2‑oxoglutarate‑dependent oxygenase, acts as an oncogene and predicts the prognosis of multiple types of cancer

“…Furthermore, MDIG deficiency sensitized glioblastoma cells to doxorubicin (25). In addition, MDIG induced tumor angiogenesis by promoting the activation of the EGFR/phosphorylated (P-) EGFR (Tyr1068)/VEGF-A/VEGF-R1/R2 pathway (26). In the light of these results, it may be hypothesized that MDIG is not only closely linked to cancer diagnosis and prognosis but may also affect chemotherapy and anti-angiogenic targeted therapy.…”

“…The experimental procedures were performed according to the manufacturer's protocol. As described in a previous study by our group (26), in brief, the day before transfection, 5 ml (5x10 4 cells/ml) of the target cells were inoculated into a T25 flask (Corning, Inc.). When confluence reached 30-50%, the cells were incubated with lentivirus at a multiplicity of infection of 20 for A549 cells and 10 for EA.hy926 cells.…”

MicroRNA‐140‐3p inhibits proliferation and promotes apoptosis in non‐small cell lung cancer by targeting MDIG

“…25,26 Moreover, MDIG can regulate lymphangiogenesis and angiogenesis in lung adenocarcinoma through influencing several signaling pathways. 27 In another study, miR-21 and Akt participated in the regulation of MDIG expression. 28 Nevertheless, its upstream regulatory mechanism remains unidentified.…”