Kurarinone targets JAK2‐STAT3 signaling in colon cancer‐stem‐like cells

Natural compounds are known to regulate stemness/self-renewal properties in colon cancer cells at molecular level. In the present study, we first time studied the colon cancer stem-like cells targeting potential of Kurarinone (KU) and explored the underlying mechanism. Cytotoxic potential of KU was checked in colon cancer cells. Colonosphere formation assay was performed to check the spheroid formation reduction potential of KU in HCT-116 cells by using phase-contrast microscopy. Stemness/self-renewal marker expression was studied at mRNA and protein levels in colonosphere. The qRT-PCR, western blot analysis, and flow cytometer techniques were used to assess the effect of KU treatment on cell cycle progression and apoptosis induction in colon cancer cells and colonosphere. Further, effect of KU treatment on pSTAT3 status and its nuclear translocation was also studied. KU treatment significantly decreased HCT-116 cell proliferation and reduced sphere formation potential at IC₃₀ (8.71 µM) and IC₅₀ (20.34 µM) concentrations compared to respective vehicle-treated groups, respectively. KU exposure significantly reduced the expression of CD44, c-Myc, Bmi-1, and Sox2 stemness/self-renewal markers in colonosphere in a dose-dependent manner. KU treatment inhibits JAK2-STAT3 signaling pathway by reducing pSTAT3 levels and its nuclear translocation in HCT-116 cells and colonosphere at IC₅₀ concentration. KU treatment significantly decreased the expression of CCND1 and CDK4 cell cycle-specific markers and arrested the HCT-116 cells and colonosphere in G1-phase. Further, KU treatment increased Bax/Bcl-2 ratio, apoptotic cell population, cleaved caspase 3, and PARP-1 in HCT-116 cells and colonosphere. In conclusion, KU treatment decreases stemness/self-renewal, induces cell cycle arrest and apoptosis in HCT-116 colonosphere by down-regulating CD44-JAK2-STAT3 axis. Thus, targeting stemness/self-renewal and other cancer hallmark(s) by KU through CD44/JAK2/STAT3 signaling pathway might be a novel strategy to target colon cancer stem-like cells.