Aneuploidy-inducing gene knockdowns overlap with cancer mutations and identify Orp3 as a B-cell lymphoma suppressor.

Abstract

Aneuploidy can instigate tumorigenesis. However, mutations in genes that control chromosome segregation are rare in human tumors as these mutations reduce cell fitness. Screening experiments indicate that the knockdown of multiple classes of genes that are not directly involved in chromosome segregation can lead to aneuploidy induction. The possible contribution of these genes to cancer formation remains yet to be defined. Here we identified gene knockdowns that lead to an increase in aneuploidy in checkpoint-deficient human cancer cells. Computational analysis revealed that the identified genes overlap with recurrent mutations in human cancers. The knockdown of the three strongest selected candidate genes (ORP3, GJB3, and RXFP1) enhances the malignant transformation of human fibroblasts in culture. Furthermore, the knockout of Orp3 results in an aberrant expansion of lymphoid progenitor cells and a high penetrance formation of chromosomal instable, pauci-clonal B-cell lymphoma in aging mice. At pre-tumorous stages, lymphoid cells from the animals exhibit deregulated phospholipid metabolism and an aberrant induction of proliferation regulating pathways associating with increased aneuploidy in hematopoietic progenitor cells. Together, these results support the concept that aneuploidy-inducing gene deficiencies contribute to cellular transformation and carcinogenesis involving the deregulation of various molecular processes such as lipid metabolism, proliferation, and cell survival.