Our current work stems from the previous identification of novel and numerous, patient-specific frailties, affecting both cancer growth and dissemination in melanoma and breast carcinomas, by means of functional in vivo shRNA-based screens. We have previously developed a series of in vivo and in vitro models derived from patients’ samples, with the aim of reconstructing tumor heterogeneity to then investigate and target it appropriately.
Genetic mapping of actionable melanoma vulnerabilities involved in the maintenance of tumor growth and metastases dissemination
We have recently developed a new platform of in vivo shRNA screens in patient-derived xenografts (PDXs) that fully recapitulate the original tumor of the patient, where we have found: i) high numerosity of validated essential genes for tumor growth in vivo; ii) high heterogeneity of candidate targets within the patients; iii) high frailty of the melanoma upon silencing of these genes; iv) essential genes with no significant mutations but specificity of activation in defined pathways (active either in the NRAS- or BRAF-mutated melanomas); v) drugs associated to specific essential genes (e.g. SMARCA4) (Bossi et al, 2016). The current project aims at defining new actionable vulnerabilities with the goal of selectively targeting either the gene or the pathways in which the gene is involved to sustain melanoma maintenance and metastasis formation. In vivo and in vitro models derived from patient’s tissue will allow to investigate the best conditions to generate maximum tumor response to the proposed single or combination treatments and to elucidate how therapy-resistant cells evolve in the tumor and disseminate and how they can be eventually targeted.
Uncover drug sensitivity in metastases to inhibit cancer progression
The mechanisms underlying metastatic spread are numerous and still not completely clarified in melanoma, as well as in breast cancer. Emerging evidence suggests that metastases are mainly promoted by a phenotypic switch occuring in the tumor cell as a consequence of an adaptive response to unfavourable microenvironmental conditions, such as loss of nutrients and oxigen, release of various cell signaling inducers and competition for cellular partners. We plan to identify which are the genes whose expression is at the basis of the switch, and to investigate which are the pathawys involved in the reprogramming of the cell plasticity in breast cancer and melanoma, to eventually target them. In particular, we will investigate how cellular reprogramming will impact on migration and metastasization in PDXs and in patient-derived 3D cultures. We will then identify genes involved in the acquisition of the metastatic phenotype by an in vitro (cell migration and invasion) and in vivo (metastases formation) shRNA-based screening approach.
Combinatorial drug testing in vitro and in vivo
The identification of new actionable genes, for which a specific drug is already available, belonging to pathways involved in cell proliferation and invasion, will allow us to choose putative combination of drugs targeting genes involved in different and/or complementary pathways to hit mechanisms leading to metastases formation and/or drug-induced resistance. We are in the process of verifying the efficacy of drug association on in vitro proliferation and migration of PDX cells, applying recommended doses for each drug to then test in vivo the best associations in the same PDXs. Even if extremely informative, PDXs are not amenable to high throughput testing and do not allow a complete study of the interactions among tumor, immune system and microenvironment upon treatment. For this reason we are building new 3D systems, which will allow a better representation of the tumoral tissue as a whole, and to exploit the response to various lines of therapy.