Loss of apical-basal polarity is an early event in the development of epithelial cancers. This model uses the Drosophila gene l(2)gl, which encodes a component of the Scribble polarity complex; this complex plays a key role in determining cell polarity and cell proliferation in epithelial cells. In human, there are two genes orthologous to Dmel\l(2)gl, the cytoskeletal proteins LLGL1 and LLGL2. Classical amorphic and hypomorphic mutations, RNAi-targeting constructs, and alleles caused by insertional mutagenesis have been generated for Dmel\l(2)gl.
See also human diseases model reports 'cancer, epithelial, Scribble-complex-related' (FBhh0000586), 'cancer, epithelial, RAS-LLGL-related' (FBhh0000588), and 'cancer, epithelial, LLGL-YAP1-related' (FBhh0000590).
Animals homozygous for loss-of-function mutations of Dmel\l(2)gl typically die during the larval stage and exhibit abnormal overproliferation of tissues, including in the brain, imaginal discs, and hematopoietic organs; cell-polarity defects are observed. Somatic clones in different regions of the wing disc differ in susceptibility to development of l(2)gl-induced overproliferation: in some regions mutant cells are eliminated from mosaic epithelia by cell competition, in other regions clones produce tumor-like overgrowths. Observing that a number of microRNAs are dysregulated in l(2)gl tumors, a specific microRNA (mir-9a) was tested phenotypically; overexpression of mir-9a was found to reduce the overgrowth phenotype caused by loss of l(2)gl function in the wing epithelium. Multiple physical and many genetic interactions for Dmel\l(2)gl have been described; see below and in the gene report for l(2)gl.
[updated Jan. 2019 by FlyBase; FBrf0222196]