In this ovarian carcinoma (OC) model, tumorigenesis is driven by expression of the Ras85DV12 and aPKCΔN.UAS targeted to the follicle epithelium via GAL4-UAS and restricted to adulthood via a temperature-sensitive GAL4 repressor. Overproliferation, loss of cell polarity, and defective differentiation are observed; metastasis is not observed. OC-bearing flies show significantly accelerated mortality compared with controls; lethality appears to arise from systemic effects of the tumor on the host, termed paraneoplasias. One of the observed changes is overproduction of multiple secreted components of the clotting cascade that trigger hypercoagulation of the hemolymph, followed subsequently by hypocoagulation. Thus this system provides a model for investigation of mechanisms of and possible treatment of tumor-driven coagulopathy.
The constitutively active Ras85D mutation, Ras85DV12, is analogous to one of the most common oncogenic mutations found in human RAS proteins. Variant(s) implicated in human disease tested (as analogous mutation in fly gene): G12V in the fly Ras85D gene (corresponds to G12V in the human KRAS, HRAS and NRAS genes).
[updated Jun. 2024 by FlyBase; FBrf0222196]
The RAS proteins are members of a large superfamily of low-molecular-weight GTP-binding proteins. The RAS proteins control signalling pathways that are key regulators of several aspects of normal cell growth and malignant transformation. Three members of the RAS family, HRAS, KRAS and NRAS, are found to be activated by mutation in human tumors. These three members are very closely related, having 85% amino acid sequence identity (Downward, 2003; pubmed:12509763).
The PKC family of serine/threonine kinases are involved in a variety of cellular processes such as proliferation, differentiation and secretion. The PKC family comprises at least eight members grouped by their activation mechanism. Unlike the classical PKC isoenzymes which are calcium-dependent, PRKCI and PRKCZ exhibit kinase activity that is independent of calcium and also independent of diacylglycerol. [Gene Cards, PRKCI and PRKCZ; 2024.06.19]
High-scoring ortholog of human PRKCI and PRKCZ (1 Drosophila to 2 human).
High-scoring ortholog of human genes KRAS, HRAS, and NRAS (many to many; multiple paralogs and orthologs in both species; for these three human genes, Ras85D is the highest-scoring ortholog in Drosophila.