title: Loss of inducible nitric oxide synthase expression in the mouse renal cell carcinoma cell line RENCA is mediated by microRNA miR-146a.
abstract: Tumor-associated macrophages can potentially kill tumor cells via the high concentrations of nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS); however, tumor-associated macrophages actually support tumor growth, as they are skewed toward M2 activation, which is characterized by low amounts of NO production and is proangiogenic. We show that the mouse renal cell carcinoma cell line, RENCA, which, on stimulation, expresses high levels of iNOS mRNA, loses its ability to express the iNOS protein. This effect is mediated by the microRNA miR-146a, as inhibition of RENCA cells with anti-miR- 146a restores iNOS expression and NO production (4.8 ± 0.4 versus 0.3 ± 0.1 μmol/L in uninhibited cells, P < 0.001). In vivo, RENCA tumor cells do not stain for iNOS, while infiltrating tumor-associated macrophages showed intense staining, and both cell types expressed iNOS mRNA. Restoring iNOS protein expression in RENCA cells using anti-miR-146a increases macrophage-induced death of RENCA cells by 73% (P < 0.01) in vitro and prevents tumor growth in vivo. These results suggest that, in addition to NO production by macrophages, tumor cells must produce NO to induce their own deaths, and some tumor cells may use miR-146a to reduce or abolish endogenous NO production to escape macrophage-mediated cell death. Thus, inhibiting miR-146a may render these tumor cells susceptible to therapeutic strategies, such as adoptive transfer of M1-activated macrophages.
authors: Institute of Pathology, Georg-August University Hospital, Göttingen, Germany.
authors: Christina
authors: C
authors: Perske
authors: Nitza
authors: N
authors: Lahat
authors: Sharon
authors: S
authors: Sheffy Levin
authors: Haim
authors: H
authors: Bitterman
authors: Bernhard
authors: B
authors: Hemmerlein
authors: Michal Amit
authors: MA
authors: Rahat
mesh_terms: D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D002465:Cell Movement; D049109:Cell Proliferation; D005260:Female; D017403:In Situ Hybridization; D007680:Kidney Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology*; D008264:Macrophages / Q000201:enzymology / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009389:Neovascularization, Pathologic; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D035683:MicroRNAs; C534190:Mirn146 microRNA, mouse; D012333:RNA, Messenger; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse