A major milestone of the project has been passed. We have performed two screens in parallel, or more accurately, one screen from two different data sources. One data source is broadly based on the cancer literature, likely genes that will affect tumour cell growth and potentially metastasis. The other data source is a published work from human datasets where cancer cells had spread to a distant site. The mutational landscape of these patients had been analysed looking for germline mutations, present in both control and tumour samples, the functional relevance of which to metastasis was not known but were found enriched across the patient group (10,000 in size). We found that the inactivation of these genes in the tumour and surrounding control cells (mimicking the germline mutation patient situation) in many cases led to transformation and induced metastasis in our in vivo tumour model. Interestingly, the patient data set was more enriched in positive hits than the "known" cancer-related gene set. We have begun to expand our coverage of this gene set further while also validating RNAi lines with qPCR.
Carcinogenesis is a multistep process, during which pre-neoplastic cells rewire signaling pathways to push normal cells towards a cancerous phenotype. This process includes triggering events that switch the behavior of benign growing tumors to malignant invasive and metastatic behavior. This final malignant invasive and metastatic stage is the ultimate cause of mortality for the majority of cancer patients. Despite its importance, there is no clear understanding of what triggers a switch to malignancy, whether it is preventable, or even reversible, arguing a clear and urgent need for
mechanistic insight to facilitate disease prevention and management.
This project presents an in vivo genetically amendable model of tumor cell switching to a malignant invasive phenotype. Unpublished results demonstrate that oncogenic Receptor Tyrosine Kinase, RTK, expression when coupled to TORC1 inhibition triggers an invasive switch. Moreover, it identifies a key component of the invasive switch, a transcription factor (GRH) downstream of the RTK, which when blocked reduces the spread of the invasive cells to control levels. The project proposes to use this system to decode the signaling pathways that enable this invasive switch, with focus on both the RTK signaling to the cytoskeletal machinery and the negative feedback signals from TORC1 that normally suppress oncogenic RTK induced cell migration. Additionally, the project proposes to elaborate upon the existing model, expanding its capabilities by introducing the ability to perform knockdown of gene function in tissue surrounding the oncogenic RTK expressing cells. This will enable screening the signaling pathways in the microenvironment that impact the growth and spread of tumor cells. This is in part motivated by the unpublished data finding that many of the GRH transcription factor target genes are secreted proteins (eg WNT pathway) and hence potentially modulate the response of the microenvironment to the invasion.
