The aqueous extract of brucea javanica reduces tumorigenicity of human lung cancer tumorspheres

Aim: Therapy to overcome drug resistance by modulating epidermal growth factor receptor (EGFR) is a viable approach to suppress the proliferation of human non-small cell lung cancer (NSCLC) cells. A previous study demonstrated that the seeds of an aqueous Brucea javanica (BJ) (L.) Merr (Simaroubaceae) extract containing quassinoid mixtures effectively inhibited the growth and alleviated tumorigenesis in H1975 cells of NSCLC by targeting T790M/L858R EGFR. This study aimed to further determine whether the aqueous BJ extract affects the enriched H1975 spheroids in suspension culture and mouse xenograft tumor models. Methods: The spheroids of NSCLC adenocarcinoma H1975 cells were enriched in a serum-free media. The growth rate of sphere propagation by aqueous BJ extract was determined in suspended culture and in colony-formation assay. BJ extract was fed orally to nude mice bearing xenograft tumors. The resected tumors were analyzed by hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, and proliferating cell nuclear antigen assessment. Various markers were used to determine the pluripotency of tumors from mice treated with different concentrations of BJ extract. Results: BJ extract was demonstrated to be effective against the propagation of the enriched spheroids. In animal models, oral administration of the aqueous BJ extract reduced spheroid tumorigenicity. The alleviated growth of the established xenograft tumors can be attributed to the reduced drug resistance and induced apoptosis without distinct adverse effects. More evidence supports activated apoptotic death attenuated spheroid stemness of tumors. Conclusion: As an effective treatment regime to assuage lung cancer, the indigenous BJ extract promises to obliterate drug resistance and the growth of cancer stem cell tumors from NSCLC cells harboring T790M/L858R EGFR.