Figure 3.

The miR-200–Zeb1–E-cadherin axis is deregulated in metastases and a subset of primary tumors. (A) Expression levels for miR-200a and miR-200c by Q-PCR normalized to an unaffected miR, miR-16. The miR-200 (also known as “miR-8”) family is organized in two clusters in the human and mouse genome. miR-200a and miR-200c are located in separate clusters, and their expression is representative of all miRs from the two clusters. ZEB1 mRNA exhibits a reciprocal expression pattern compared with miR-200 in that it is low in standard RIP-Tag tumors but up-regulated in met-like primary tumors and liver metastases. E-cadherin expression mirrors miR-200 expression and is mutually exclusive with ZEB1. (B) H&E (panels i,iv) and E-cadherin immunofluorescence at 10× (panels ii,v) and 20× (panels iii,vi) magnification for a noninvasive RT2 tumor (panels i–iii) or a highly invasive IC2 tumor (panels iv–vi). (T) Tumor; (P) normal exocrine pancreas. Noninvasive RT2 tumors express E-cadherin, whereas expression is not detected in IC2s. Note the even higher levels of E-cadherin in normal exocrine pancreas as compared with noninvasive tumors, which are nevertheless positive. (C,D) RNA (C) and protein (D) levels of ZEB1 and E-cadherin following electroporation of a miR-200c mimic or mimic control oligos into βTC3 or βTC4 cells demonstrate their regulatory interconnection. Bar graphs show average plus standard deviation.