PROJECT SUMMARY Small extracellular vesicles(sEVs), often referred as exosomes, are short- and long-distance mediators of intercellular communication. Secretion of sEVs by cancer contributes to metastasis, chemoresistance, and progression of cancer. Recent unpublished work in our lab revealed the impact of cancer-derived sEVs in promoting invasion and disrupting the epithelial barrier of non-tumorigenic epithelial cells. Therefore, it is not surprising that the study of sEVs in cancer has gained attention. Indeed, sEV secretion is upregulated in cancer cells; however, specific mechanisms involved in the dysregulation of sEV secretion and biogenesis in cancer cells is understudied. Therefore, the goal of this proposal is to identify new mechanism that modulate secretion and uptake of cancer-derived sEVs. To further uncover the mechanism involved in cancer sEVs dynamics, the proposal will address the following innovative aims. In aim 1, we will determine the impact of mutant KRAS, one the most frequently altered oncogene in cancer, on the secretion and biogenesis of sEVs. This aim will evaluate the hypothesis that mutant KRAS promotes the secretion of sEVs through impairment of the sEVs biogenesis pathway. In aim 2, we will discover novel uptake pathways used by non-small cell lung cancer (NSCLC) derived sEVs to enter non-tumorigenic cells. A CRISPR-based knockout screen will be conducted to identify genes, that when lost, impair NSCLC sEVs uptake. With these studies we aim to determine the mechanisms by which exosome-mediated cell-cell communication confers oncogenic properties to the host cell. In addition to identifying new molecular mechanisms in cancer and sEVs biology this project also includes a detailed career development plan that will provide Ms. Soto additional mentoring and training that will support her transition into an independent investigator in the cancer biology field.