Fig. 6

miR-346 and NORAD Modulate PC Therapeutic Response and In Vivo Tumour Growth. A Charts indicating percentage of PC patients from the indicated cohorts demonstrating matching PTEN and MIR346 copy number status. B SRB assay analysis of PC cell proliferation in response to miR-346 transfection (7.5 nM) ± olaparib PARP inhibitor (i,ii - 5 μM) or carboplatin (iii,iv – 2.5 μM) in 22RV1 (i,iii) or C42 (ii, iv) cells. C, D Relative tumour growth of C42/miR-346 (C) and C42/shNORAD (D) xenograft tumours and survival of host NSG male mice ± Dox, n = 7 per group. E Immunohistochemistry analysis of Ki67 protein levels in FFPE sections of dox-treated C42/NC, C42/miR-346 and C42/shNORAD xenograft tumours from NSG mice. Scale bar = 250 μm. F Model for miR-346:NORAD Regulation of DNA Damage in Prostate Cancer. Under high NORAD/ low miR-346 conditions, NORAD drives target directed microRNA decay (TDMD) of miR-346 to inhibit miR-346-induced DNA damage and prevent miR-346 inhibition of NORAD activity. High NORAD levels result in reduced response to DNA damaging agents. Under low NORAD/ high miR-346 conditions, miR-346 decreases NORAD transcript levels and disrupts NORAD:PUM2 association, liberating PUM2 to turnover DNA repair transcripts. In addition, miR-346 associates with chromatin to accelerate transcription. This results in R-loop formation and increased collisions between transcription and DNA repair machinery, leading to DNA replication stress and double-stranded DNA breaks that increase response to DNA damaging therapeutics in prostate cancer. * P ≤ 0.05, ** P ≤ 0.005, *** P ≤ 0.0001. See also Fig. S13–17