ETV7 as a novel potential target to address cancer aggressiveness and chemoresistance

Breast cancer and colon cancer are the first and third most common cancers worldwide. Despite advancements in diagnosis and treatment, breast cancer remains the leading cause of cancer death in women, while colon cancer is the second leading cause of cancer-related deaths worldwide. For these reasons, it is extremely important to develop new therapeutic strategies and to better understand the factors underlying breast and colon cancer biology. This study focuses on ETV7, a poorly studied ETS transcription factor with reportedly increased expression in various types of cancers, including breast and colon cancer. In both of these cancer types, ETV7 has been correlated with increased aggressiveness. Moreover, ETV7 was described as a promoter of chemoresistance to doxorubicin in breast cancer cells and to 5-fluorouracil in colon cancer. Here, we confirmed the role of ETV7 in breast and colon cancer cells’ aggressiveness by analysing their phenotypes following ETV7 knockdown. Furthermore, results demonstrated that ETV7 depletion can restore sensitivity to treatment with doxorubicin, 5-fluorouracil, and irinotecan in both breast and colon cancer cellular models, highlighting the possibility of pharmacologically targeting ETV7 in order to increase the therapeutic potential of standard drug treatment. Being a transcription factor, ETV7 lacks the canonical pocket usually targeted by small-molecules inhibitors; moreover, the only information available on ETV7 structure are computationally predicted based on the aminoacidic sequence. In this work, we overcame these challenges by producing crystals of the ETV7-PNT domain, responsible for its dimerization, which is necessary for its function. The high-resolution analysis of the ETV7-PNT domain provided for the first time the three-dimensional structure of this crucial domain of the protein, together with information that gave us the possibility to establish a drug design approach. To date, no molecule able to inhibit ETV7 is available on the market; therefore, a collaboration was initiated with the laboratory of Prof. Maria Letizia Barreca to develop and test a panel of small molecules designed based on the three-dimensional structure of the ETV7 dimerization domain. SPR and nano-DSF studies were conducted on the molecules to find putative binders. Among the 60 tested compounds, three demonstrated the ability to bind to the ETV7-PNT domain; of these, one compound showed a good dose-response correlation, demonstrating its potential to become the starting point for a second screening campaign. Collectively, results confirm ETV7 as a mediator of cancer cell aggressiveness, making it an attractive target to improve the efficacy of breast and colon cancer therapy and paving the way for the development of pharmacological inhibitors of ETV7.