Non-small cell lung cancer (NSCLC), the most common type of lung cancer, is the leading cause of cancer related deaths in United States. Only 24% of NSCLC patients survive 5-years post diagnosis, which could be attributed to the lack of efficient treatment strategies at the metastatic stage. Thus, understanding the biological mechanisms that promote NSCLC metastasis is critical for developing effective cancer-specific therapeutic agents. The development of cancer metastasis is greatly driven and influenced by intercellular communication. Key mediators of cell-to-cell communication are small extracellular vesicles (sEVs) of approximately 100-150 nm in diameter, often referred as exosomes. Previous report revealed that increased levels of exosomes in NSCLC patients correlated with lower overall survival. Indeed, secretion of sEVs by cancer cells can induce malignant transformation of non-cancerous cells nearby or at distant locations through influencing pre-metastatic niche formation. Therefore, biogenesis and release of cancer derived sEVs are determinant steps for the development of tumor metastasis. However, the mechanisms through which sEVs are produced and secreted by cancer cells are yet to be determined. Here, we isolated and characterized sEVs from a panel of NSCLC cell lines (H358, Calu6, H460, SKMES-1) and non-tumorigenic cells (BEAS-2B and HBEC) to identify mechanisms involved in the elevated secretion of EVs by cancer cells. Contrary to what has been previously reported in literature, our data demonstrated that not all cancer cell lines release high levels of sEVs. Our data suggests that elevated secretion of sEVs could be driven by specific mutations and oncogenic signaling in cancer cells. Among all the cell lines tested, H358 cells which harbor the infamous G12C mutation in KRAS, had the highest sEV release. Therefore, we hypothesize that the KRASG12C can drive high sEV production and secretion in H358 cells. Our preliminary data suggests that siRNA mediated knockdown of oncogenic KRAS signaling in H358 cells significantly decreases secretion of sEVs. Ongoing studies aim to pinpoint the detailed mechanisms by which cancer cells utilize KRAS oncogenic signaling to promote EV biogenesis pathways and tumorigenesis. The current study will provide the foundation to developed new therapeutic strategies against tumor sEVs-driven metastasis. Citation Format: Zulaida M. Soto Vargas, Ikjot Singh Sohal, Humna Hasan, David Arteaga, Andrea L. Kasinski. Uncovering mechanisms of biogenesis and secretion of small extracellular vesicles in non small cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1581.

Mutations in Kristen rat sarcoma homolog (KRAS) occur in about 25% of cancers, making this protein one of the most frequently altered genes in cancer. KRAS mutations are not only associated with poor patient survival, but also with increased tumor aggressiveness and metastasis. Tumor development and metastasis are impacted by intercellular communication. Key mediators of cell-to-cell communication include vesicles secreted by cells, also known as extracellular vesicles (EVs). EVs released by cancer cells can mediate malignant transformation of non-cancerous cells as well as influence pre-metastatic niche formation. Conversely, inhibiting the secretion and release of EVs by cancer cells decreases tumor growth and metastasis. However, the mechanisms through which EVs drive tumorigenesis in KRAS mutant tumors are still understudied. Our lab recently reported that EVs from lung cancer cells drive invasion of non-tumorigenic lung epithelial cells. Here, we found that KRAS oncogenic signaling in the donor cells contributes to the EV-driven migration and invasion of non-tumorigenic lung epithelial cells. Previous studies have demonstrated that KRAS signaling drives immune evasion and promotes an “immune cold” tumor microenvironment. Our preliminary studies showed that EVs derived from KrasG12C lung cancer cells (H358) inhibit T cell proliferation and that blocking KRASG12C signaling, using ARS-1620 (KrasG12C inhibitor), impairs EV-driven T cell immunosuppression. We performed a comprehensive proteomic comparison between EVs isolated from H358 treated with ARS-1620 and those isolated from cells treated with DMSO (vehicle) and identified proteins involved in migration and invasion, such as LAMB-3, to be downregulated in EVs isolated from ARS-1620 treated cells. Ongoing studies aim to pinpoint the detailed mechanisms by which cancer cells utilize mutant KRAS signaling to promote loading of oncogenic cargo into EVs, and the resulting contributions to tumorigenesis and immune evasion. Citation Format: Zulaida M. Soto Vargas, David C. Arteaga, Ikjot S. Sohal, Humna Hasan, Andrea L. Kasinski. Impact of KRAS oncogenic signaling in tumorigenesis and immune evasion driven by extracellular vesicles (EVs). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3639.