The Drosophila posterior midgut is closely analogous to the mammalian small intestine; the midgut epithelium is maintained by frequent division of self-renewing intestinal stem cells (ISCs). A model of intestinal cancer has been developed using ISC expression of an activated form of the Drosophila RAS gene Ras85D in combination with reduced expression of Notch (N), effected by RNAi.
Ras85D-N tumor growth correlates with an expansion of tracheal cell branching, similar to increased angiogenesis observed for human cancers. Using transplant of ISC tumor masses generated using this system, the role of btl (ortholgous to FGFR1-4 in human) has been assessed. btl is required for the process of tracheal remodeling observed in several ISC cancer models in flies.
See related human disease model reports cancer, intestinal stem cell, RAS-related (FBhh0001032) and cancer, intestinal stem cell, NOTCH-related (FBhh0001354).
[updated Jun. 2021 by FlyBase; FBrf0222196]
Moderate- to high-scoring ortholog of human NOTCH1, NOTCH2, NOTCH3, NOTCH4 (1 Drosophila to 4 human). Dmel\N shares 43-44% identity and 56-57% similarity with NOTCH1 and NOTCH2.