A protocol for genetic induction and visualization of benign and invasive tumors in cephalic complexes of Drosophila melanogaster.

Drosophila has illuminated our understanding of the genetic basis of normal development and disease for the past several decades and today it continues to contribute immensely to our understanding of complex diseases (1-7). Progression of tumors from a benign to a metastatic state is a complex event (8) and has been modeled in Drosophila to help us better understand the genetic basis of this disease (9). Here I present a simple protocol to genetically induce, observe and then analyze the progression of tumors in Drosophila larvae. The tumor induction technique is based on the MARCM system (10) and exploits the cooperation between an activated oncogene, Ras(V12) and loss of cell polarity genes (scribbled, discs large and lethal giant larvae) to generate invasive tumors (9). I demonstrate how these tumors can be visualized in the intact larvae and then how these can be dissected out for further analysis. The simplified protocol presented here should make it possible for this technique to be utilized by investigators interested in understanding the role of a gene in tumor invasion.