Drosophila genes that affect centrosome function were assessed for capacity to produce tumors in a larval brain system. Candidate mutations were characterized using a tissue transplant assay for neoplastic capacity in which larval brain tissue is transplanted into the abdomens of wild-type adult female hosts. For loss-of-function mutations in Sas-4, polo, and aurA, brain tissue transplants exhibited unrestrained growth, filling the abdominal cavity, and killing a subset of the hosts; small colonies scattered on different parts of the host's anatomy (micrometastases) are observed. The tumors can be maintained by serial retransplantation; these tumor lines exhibit increasing amounts of polyploidy and chromosome instability (CIN).
Based on two additional observations, it has been postulated that development of tumors in neural tissues due to centrosome dysfunction is caused primarily by perturbation of the self-renewing asymmetric division of neural stem cells, rather than by CIN. First, other sources of CIN (genetic or environmental) did not result in significant tumorigenic phenotypes in the larval brain transplantation assay. Second, when imaginal disc (epithelial) tissues from loss-of-function mutations in Sas-4, polo, and aurA were transplanted into the abdomens of wild-type adult female hosts, no tumorous growth was observed.
See related human disease model reports 'cancer, models of chromosomal instability' (FBhh0000763) and 'microcephaly, centrosome-SAC dysfunction' (FBhh0000778).
[updated May 2019 by FlyBase; FBrf0222196]
Lack of centrosomes does not prevent spindle assembly, but spindle assembly is inefficient and accuracy of chromosome segregation may be compromised (FBrf0235458 and references cited therein).
A number of the human genes implicated in primary microcephaly encode proteins that are components of centrosomes (Patwardhan, et al., 2018, pubmed:29352115; Alcantara and O'Driscoll, 2014, pubmed:24816482).
High-scoring ortholog of human CENPJ (1 Drosophila to 1 human); additional low-scoring orthologs in human. Dmel\Sas-4 shares 24% identity and 39% similarity with the human CENPJ gene.
High-scoring ortholog of human PLK1; low- to moderate-scoring ortholog of human PLK2 and PLK3 (1 Drosophila to 3 human). Dmel\polo shares 52% identity and 71% similarity with the human PLK1 gene.
Moderate- to high-scoring ortholog of human AURKB, AURKC, and AURKA (2 Drosophila to 3 human). Dmel\aurA shares 48-55% identity and 64-74% similarity with the human genes.