UNCOVERING EPIGENETIC VULNERABILITIES IN INTESTINAL CANCER DEVELOPMENT

Colorectal cancer (CRC) arises from a multi-step process leading to the progressive accumulation of genetic and epigenetic mutations, thus causing deregulation in homeostasis followed by neoplastic transformation.Epigenetic and genetic alterations are able to induce a constitutive activation of the WNT signaling pathway, whose aberrant activity converges into deregulation of proliferation, differentiation and cell death pathways. The most common causes of WNT pathway hyper-activation are APC loss of function, or b-catenin constitutive activation mutations. Despite this knowledge of aberrant WNT activity, upstream interference with this signaling pathway induces adverse effects due to high cross-talk with other pathways, highlighting a need to find alternative ways to indirectly target the effectors of this pathway. Deregulated pathways in CRC provoke aberrant signaling that converges into the nucleus where transcription and chromatin-remodeling factors cooperate to maintain or modify the identity of a cell. In recent years, several studies have been focused on epigenetic players, which act by depositing specific and reversible post-translational modifications. For this reason they are being recognized as promising new targets for the development of cancer therapeutic strategies. In this context, my project takes advantage of murine 3D intestinal organoid cultures, carrying oncogenic deregulations of the WNT pathway, as a platform for pooled and arrayed RNA interference screens, to identify novel regulators that control the nuclear/transcriptional aspect of this oncogenic pathway. I also implemented the validation of selected targets in human metastatic colorectal cancer organoids to highlight their clinical relevance. Moreover, since several chromatin modifier inhibitors have been already developed, the findings of this project should prompt the development of new molecules for CRC treatment to target the novel sensitivities I identified. Finally, this project generated important technical knowledge through this pioneering approach that will open up the possibility of performing functional screens in other tissues from which organoid cultures have already been established.