Characterization of the E3 ubiquitin ligase HERC1 as an important regulator of tumor cell migration and invasion.

JULIANA H. ENRIQUE´ STEINBERG; FABIANA ALEJANDRA ROSSI; JOAQUIN M ESPINOSA; EZEQUIEL CALVO-ROITBERG; MARIO ROSSI

Buenos Aires

Congreso; LVI SAIB / XV SAMIGE Meeting; 2020

Tumor cell migration and invasion into adjacent tissues is one of the hallmarks of cancer and the first step towards secondary tumors formation. Tumoral dissemination in cancer patients is associated with a significant reduction in their survival and quality of life, and this process is considered an unmet clinical need in the treatment of this disease, particularly in breast cancers characterized by high aggressiveness and metastatic potential. The ubiquitination pathway plays a fundamental role in the maintenance of protein homeostasis both in normal and stressed conditions and its dysregulation has been associated with malignant transformation and invasive potential of tumor cells, thus highlighting its value as a potential therapeutic target. Therefore, in order to identify novel molecular targets of tumor cell migration and invasion within components of this pathway, we performed a pooled genetic screen using an shRNA library against ubiquitination pathway-related genes and a highly invasive breast cancer derived cell line. To this end, we set up a protocol to specifically enrich positive migration regulator candidates that involved in vitro and in vivo selection steps. We identified the E3 ligase HERC1 among the candidates, a huge protein involved in intracellular membranes trafficking and whose role in the control of the metastatic capability of tumor cells has not been reported yet. We demonstrated that its silencing reduces the migratory and invasive potential of breast cancer cells using in vitro experiments. We extended our investigation in vivo and confirmed that mice injected with HERC1 depleted cells display increased tumor-free survival, as well as a delay in the onset of the tumor formation and a significant reduction in the appearance of metastatic foci, indicating that tumor cell invasion and dissemination is impaired. Finally, we conducted an in-silico analysis using publicly available protein expression data and observed an inverse correlation between HERC1 expression levels and breast cancer patients? overall survival, suggesting that its overexpression could be a prognostic marker in patients with breast cancer. Altogether, our results highlight the potential of Herc1 as a novel putative therapeutic candidate for cancer treatment.