Figure 1.

(A) Schematic representation of five Dicer mRNA variants and the corresponding proteins. Using AceView (http://www.AceView.org), transcription from the Dicer gene putatively produces 14 mRNAs, 11 alternatively spliced variants and 3 full-length forms. The cartoon shows the three full-length mRNA variants (a, b and c) and the corresponding full-length protein (218 kDa) and the two alternatively spliced variants (d and e) and their corresponding proteins (respectively, 113 and 93 kDa). For the mRNA, alternating colours indicate the different exons and grey bars represent 5′ and 3′UTRs. Domain structures are represented on proteins: green areas represent the ribonuclease domains, grey areas represent the dsRNA binding domain, and light green areas represent the helicase C domain. ↓ indicates miR-103/107 target sites in the 3′UTR region, ^*indicates let-7 target sites in the coding and 3′UTR regions. 3′UTR variant a is 4269 bases long, 3′UTR variant b is 4270 bases long, 3′UTR variant c is 175 bases long and contains no miRNA target sites and ^**indicates two let-7 sites. The 3′UTR of variant d is 431 bases long (corresponding to the partial intron 23 sequence) and the 3′UTR of variant e is 30 bases long (with no miRNA target sites). (B) Expression of full-length Dicer protein and d+e isoforms in breast cancer cell lines. Western blot analysis of full-length and truncated variant isoforms of Dicer levels in 10 breast cancer cell lines. Actin was used as a loading control. (C) Expression of full-length Dicer and d and e isoform proteins during EMT. Western blot analysis of Dicer expression in HMEC+hTERT (immortalised human mammary epithelial cells stably expressing hTERT) cell line and in HMEC+hTERT+RAS (immortalised HMEC+hTERT transfected with RAS oncogene) cells. Actin was used as a loading control. (E) indicates epithelial phenotype; (M) indicates mesenchymal phenotype; (E/M) indicates a mixed phenotype.