Hh signaling inhibitors from Vitex negundo; naturally occurring inhibitors of the GLI1–DNA complex

Abstract

The hedgehog (Hh) signaling pathway has crucial roles in embryonic development, cell maintenance and proliferation, and is also known to contribute to cancer cell growth. New naturally occurring Hh inhibitors (1, 7 and 9) were isolated from Vitex negundo using our previously constructed cell-based assay. Bioactivity guided isolation provided 9 natural compounds including a new diterpene, nishindanol (9). Compounds 7 and 9 showed cytotoxicity against cancer cell lines in which Hh signaling was aberrantly activated. Vitetrifolin D (7; GLI1 transcriptional inhibition IC50 = 20.2 μM) showed inhibition of Hh related protein (PTCH and BCL2) production. Interestingly, the constructed electrophoresis mobility shift assay revealed that vitetrifolin D (7) disrupted GLI1 binding on its DNA binding domain. epi-Sclareol (8; inactive), possessing a similar structure to 7, did not show inhibition of GLI1–DNA complex formation. This is the first example of naturally occurring inhibitors of GLI1–DNA complex formation.

Hedgehog inhibitors from Artocarpus communis and Hyptis suaveolens

“…5) using the GLI1-DNA complex, as previously described. 19 Interestingly, despite the weak GLI1 transcriptional inhibition of compound 1, it showed potent inhibition of GLI1-DNA complex formation, whereas inactive 5 did not inhibit the complex Figure 1. Schematic of the constructed assay system.…”

“…1), allowing us to identify several potent Hh inhibitors such as physalin B, 14 physalin F, 14 colubrinic acid, 15 cardenolides, 16 taepeenin D, 17 flavonoid glycoside, 18 vitetrifolin D, 19 and physalin H. 20 During the present investigation, a screening study revealed that Artocarpus communis and Hyptis suaveolens exhibit inhibitory activity against the Hh signal. Here we report five new natural products (6, 7, and 9-11) as moderate Hh inhibitors and four as potent Hh inhibitors (12)(13)(14)(15).…”

Hedgehog/GLI-mediated transcriptional activity inhibitors from Crinum asiaticum

“…Using this assay system, we isolated a number of naturally occurring inhibitors of the Hh signaling pathway, for example, physalin B and physalin F [12], colubrinic acid [13], cardenolides [14], taepeenin D [15], a flavonoid glycoside [16], acoschimperoside P [17], and vitetrifolin D [18]. During the screening of the plant extract library with the assay system, we identified some plant extracts as GLI1-mediated transcriptional inhibitor samples.…”

Hedgehog inhibitors from Withania somnifera

“…2). Previously, we have reported several naturally occurring Hh inhibitors, such as physalin B, 14 physalin F, 14 colubrinic acid, 15 caldenolides, 16 taepeenin D, 17 flavonoid glycoside, 18 vitetrifolin D, 19 and physalin H, 20 using this bioactivity-guided isolation assay.…”