Growth Suppression of Cancer Spheroids With Mutated KRAS by Low-toxicity Compounds from Natural Products.

ABSTRACT

BACKGROUND/AIM: Among compounds from natural products selectively suppressing the growth of cancer spheroids, which have mutant (mt) KRAS, NP910 was selected and its derivatives explored. MATERIALS AND METHODS: The area of HKe3 spheroids expressing wild type (wt) KRAS (HKe3-wtKRAS) and mtKRAS (HKe3-mtKRAS) were measured in three-dimensional floating (3DF) cultures treated with 18 NP910 derivatives. The 50% cell growth inhibition (GI50) was determined by long-term 3DF (LT3DF) culture and nude mice assay. RESULTS: We selected NP882 (named STAR3) as the most effective inhibitor of growth of HKe3-mtKRAS spheroids with the least toxicity among NP910 derivatives. GI50s of STAR3 in LT3DF and nude mice assay were 6 µM and 30.75 mg/kg, respectively. However, growth suppression by STAR3 was observed in 50% of cell lines independent of KRAS mutation, suggesting that the target of STAR3 was not directly associated with KRAS mutation and KRAS-related signals. CONCLUSION: STAR3 is a low-toxicity compound that inhibits growth of certain tumour cells.