Brusatol

Papillary renal cell carcinoma (pRCC) is the second most frequent renal cancer subtype but has no indicated targeted treatments. MET inhibition may be a treatment for MET‐driven pRCC, but there is a large group of non‐MET‐driven pRCC without targeted therapy. Activation of NRF2‐ARE pathway has been suggested to be involved in pRCC. To study the relevance of the NRF2‐ARE pathway, we characterized 60 pRCCs by copy number analysis and Whole Exome Sequencing. Because stabilisation of NRF2 results in enhanced expression of NQO1, a reductase that prevents production of reactive oxygen species, protein expression of NQO1 was analysed by immunohistochemistry (IHC) from tissue microarrays (TMAs) and by enzymatic activity assay. Finally, patient‐derived pRCC cells (PDCs) were applied for drug profiling with 18 NRF2‐ARE pathway inhibitors. We identified MET mutations in 5%, and mutations in four genes of NRF2‐ARE pathway (NFE2L2, KEAP1, CUL3 and BACH1) in 10% of 60 pRCC samples. IHC analysis of TMAs of 638 renal cancers showed the correlation of the expression of NQO1 with poor survival outcome (p < .001) and high tumour grade (p < .001) and stage (p < .001) in pRCC. NQO1 mRNA, protein levels and enzymatic activity were increased in 56% of matched pRCC tissue samples and patient‐derived cells (PDCs, n = 9). Drug screening revealed that Brusatol and Convallatoxin are potential novel drugs for pRCC. Inhibition of NRF2 represents a novel therapeutic approach for MET‐independent pRCC patients.

Osteosarcoma (OS), the most frequent type of primary bone cancer, has a poor prognosis in metastatic cases, with overall 5-year survival rates stagnating at 20 %-30 %. This highlights the critical need for innovative therapies to address the significant survival gap between metastatic and non-metastatic cases. Brusatol (BRU), a compound extracted from Brucea javanica, has shown promising anti-tumor properties in various cancers; however, its effects on OS have yet to be investigated.

To investigate the anti-tumor mechanisms of BRU in OS and evaluate its potential therapeutic efficacy, with a particular focus on its impact on lipid metabolism and related signaling pathways.

In vitro experiments to assess the anti-tumor effects of BRU involved colony formation, CCK-8, Transwell analysis, as well as flow cytometry. RNA sequencing was conducted to identify transcriptional changes in BRU-treated cells. The mechanism of action was investigated through analysis of lipid metabolism and key signaling pathways. Therapeutic efficacy and safety were evaluated in vivo using xenograft models.

BRU significantly inhibited OS cell proliferation, migration, and invasion, while also inducing G2/M phase cell cycle arrest as well as promoting apoptosis. Transcriptome analysis revealed that BRU affected lipid metabolism-related genes and suppressed the PI3K/AKT and MAPK pathways. BRU treatment reduced fatty acid synthase expression and free fatty acid content in OS cells. In vivo experiments demonstrated that BRU effectively restricted xenograft growth.

This study revealed that BRU exhibits potent anti-tumor effects in OS by modulating lipid metabolism through the PI3K/AKT and MAPK pathways.