Linderapyrone analogue LPD-01 as a cancer treatment agent by targeting importin7

The Wnt/ β -catenin signaling pathway plays important roles in several cancer cells, including cell proliferation and development. We previously succeeded in synthesizing a small molecule compound inhibiting the Wnt/ β -catenin signaling pathway, named LPD-01 ( 1 ), and 1 inhibited the growth of human colorectal cancer (HT-29) cells. In this study, we revealed that 1 inhibits the growth of HT-29 cells stronger than that of another human colorectal cancer (SW480) cells. Therefore, we have attempted to identify the target proteins of 1 in HT-29 cells. Firstly, we investigated the effect on the expression levels of the Wnt/ β -catenin signaling pathway - related proteins. As a result, 1 inhibited the expression of target proteins of Wnt/ β -catenin signaling pathway (c-Myc and Survivin) and their genes, whereas the amount of transcriptional co-activator ( β -catenin) was not decreased, suggesting that 1 inhibited the Wnt/ β -catenin signaling pathway without affecting β-catenin. Next, we investigated the target proteins of 1 using magnetic FG beads. Chemical pull-down assay combined with mass spectrometry suggested that 1 directly binds to importin7. As expected, 1 inhibited the nuclear translocation of importin7 cargoes such as Smad2 and Smad3 in TGF- β -stimulated HT-29 cells. In addition, the knockdown of importin7 by siRNA reduced the expression of target genes of Wnt/ β -catenin signaling pathway. These results suggest that importin7 is one of the target proteins of 1 for inhibition of the Wnt/ β -catenin signaling pathway. Graphical abstract