A time course transcriptomic analysis of host and injected oncogenic cells reveals new aspects of Drosophila immune defences

Oncogenic RasV12 cells (1) injected into adult males proliferated massively, after a lag period of several days, and led to the demise of the flies after 2 to 3 weeks. The injection induced an early massive transcriptomic response which unexpectedly included more than 100 genes encoding chemoreceptors of various families. The kinetics of induction and the identities of the induced genes differed markedly from the responses generated by injections of microbes. During the following periods hundreds of genes were upregulated attesting to intense catabolic activities in the flies, to active tracheogenesis and cuticulogenesis as well as to stress and inflammation-type responses. Eleven days after the injections, GFP-positive oncogenic cells isolated from the host flies exhibited a transcriptomic profile markedly different from that of the host and distinct from that at the time of their injection, including in particular upregulated expression of genes typical for cells engaged in the classical antimicrobial response of Drosophila