This report describes a Drosophila model of cancer that combines overexpression of the Dmel\Nek2 gene (orthologous to human NEK2) with a multi-component fly RAS-SRC cancer model. NEK2 encodes a protein kinase involved in the control of centrosome separation and bipolar spindle formation. Overexpression of human NEK2 is observed in multiple different cancers and is thought to contribute to dysregulation of the centrosome cycle and aneuploidy. Addressed in this model is the possibility that the initial impact of NEK2 overexpression occurs at an earlier stage, and is not confined to increasing chromosomal instability.
The human NEK2 gene has not been introduced into flies.
A previously developed Drosophila model of cancer uses an activated mutation in the fly RAS protein Ras85D (Ras85DV12) combined with a loss-of-function mutation in the fly gene orthologous to the human CSK kinase gene, Dmel\Csk. Phosphorylation by CSK suppresses the activity of multiple genes, including the SRC proto-oncogene. See the human disease model report 'cancer, multiple, RAS-CSK(SRC)-related' (FBhh0000664). Assessed using somatic clones in larval eye discs, RAS(activated)-CSK mutant clones exhibit limited tissue overgrowth. Addition of Dmel\Nek2 overexpression results in increased overgrowth and appearance of secondary tumors in other parts of the body. The overgrowth phenotype is reduced and the metastatic phenotype completely suppressed by feeding of a drug known to inhibit the activity of the PI3K/AKT pathway.
[updated Jul. 2019 by FlyBase; FBrf0222196]
NEK2 encodes a protein kinase involved in the control of centrosome separation and bipolar spindle formation in mitotic cells and chromatin condensation in meiotic cells. The protein is localized to the centrosome, and undetectable during G1 phase, but accumulates progressively throughout the S phase, reaching maximal levels in late G2 phase. [Gene Cards, NEK2; 2019.07.23]
One to one: 1 human to 1 Drosophila; additional more distantly related gene(s) in both species.
High-scoring ortholog of human CSK; moderate-scoring ortholog of human MATK (1 Drosophila to 2 human); Dmel\Csk shares 62% identity and 75% similarity with the human CSK gene.
Moderate- to high-scoring ortholog of human NEK2 (1 Drosophila to 1 human); additional more distantly related gene(s) in both species. Dmel\Nek2 shares 36% identity and 52% similarity with the human gene.
High-scoring ortholog of human genes KRAS, HRAS, and NRAS (many to many; multiple paralogs and orthologs in both species). Dmel\Ras85D shares 78-86% identity and 86-92% similarity with KRAS, HRAS, and NRAS; for these three human genes, Ras85D is the highest-scoring ortholog in Drosophila.