Nebulized inhalation of extracellular vesicles containing SPOCK2 suppresses lung adenocarcinoma progression via MAPK inhibition

Aberrant expression of SPARC/osteonectin, cwcv and kazal-like domains proteoglycan 2 (SPOCK2) plays a role in the development and progression of several human cancers. However, the importance of its expression and function in lung adenocarcinoma (LUAD) remains unclear. The present study aimed to elucidate the role of SPOCK2 in the growth of LUAD and propose a novel therapeutic insight for LUAD through SPOCK2. SPOCK2 protein expression was significantly reduced in LUAD tissues and cells by Immunohistochemical assay and Western blot. CCK-8, colony formation, and Transwell assays were used to demonstrate that SPOCK2 overexpression inhibited both proliferation and migration of LUAD cells in vitro. This inhibition of tumor growth was further confirmed by a LUAD xenograft mouse model in vivo. To explore downstream target signal of SPOCK2 in LUAD, RNA transcriptome sequencing was performed and enrichment analysis showed an association between SPOCK2 expression and the MAPK pathway. Furthermore, HEK293T cells were modified with SPOCK2, and extracellular vesicles (EVs) containing SPOCK2 (SPOCK2-EVs) were collected through ultra-high-speed centrifugation. Interestingly, co-culture with SPOCK2-EVs significantly increased SPOCK2 levels within LUAD cells. Furthermore, SPOCK2-EVs effectively inhibited LUAD growth in vitro and in vivo studies. Because directly injecting SPOCK2-EVs into tumors presents challenges for internal organs, we investigated the efficacy of nebulized SPOCK2-EVs for LUAD treatment. Consistent with our findings from intratumoral injection, nebulized inhalation of SPOCK2-EVs resulted in significant inhibition of LUAD growth. These results strongly suggest that SPOCK2 released by HEK293T-EVs can effectively inhibit LUAD tumor growth and hold promise for future clinical translation in cancer therapy.