The antiproliferative and proapoptotic effects of cladosporols A and B are related to their different binding mode as PPARγ ligands

Abstract

a b s t r a c tCladosporols are secondary metabolites from Cladosporium tenuissimum characterized for their ability to control cell proliferation. We previously showed that cladosporol A inhibits proliferation of human colon cancer cells through a PPARc-mediated modulation of gene expression. In this work, we investigated cladosporol B, an oxidate form of cladosporol A, and demonstrate that it is more efficient in inhibiting HT-29 cell proliferation due to a robust G0/G1-phase arrest and p21 waf1/cip1 overexpression. Cladosporol B acts as a PPARc partial agonist with lower affinity and reduced transactivation potential in transient transfections as compared to the full agonists cladosporol A and rosiglitazone. Site-specific PPARc mutants and surface plasmon resonance (SPR) experiments confirm these conclusions. Cladosporol B in addition displays a sustained proapoptotic activity also validated by p21 waf1/cip1 expression analysis in the presence of the selective PPARc inhibitor GW9662. In the DMSO/H 2 O system, cladosporols A and B are unstable and convert to the ring-opened compounds 2A and 2B. Finally, docking experiments provide the structural basis for full and partial PPARc agonism of 2A and 2B, respectively. In summary, we report here, for the first time, the structural characteristics of the binding of cladosporols, two natural molecules, to PPARc. The binding of compound 2B is endowed with a lower transactivation potential, higher antiproliferative and proapoptotic activity than the two full agonists as compound 2A and rosiglitazone (RGZ).

A compound-based proteomic approach discloses 15-ketoatractyligenin methyl ester as a new PPARγ partial agonist with anti-proliferative ability

“…In the docking model, 1 is positioned far from H12 and binds close to, and strongly stabilizes, the H3/β-sheet/Ω-loop region of the LBD, similar to other PPARγ partial agonists such as BVT.13, MRL-24 and nTZDpa37. We recently demonstrated that also cladosporol B, a secondary metabolite from Cladosporium tenuissimum , makes no direct contacts with H12 residues, a hallmark of full agonists such as TZDs, but preferentially stabilizes H3 through closer hydrophobic contacts or H-bonds made with residues of this helix (S289, F282, Q283 and Q286)46 (Fig. 4).…”

“…The PPRE-Luc plasmid contains a luciferase reporter gene under the transcriptional control of three copies of the PPRE (Peroxisome Proliferator Response Element) derived from Acyl-CoA oxidase gene fused upstream to the herpes simplex thymidine kinase (TK) promoter, as described46. The RSV-βGal plasmid, expressing β-galactosidase gene, driven by the strong Rous Sarcoma Virus (RSV) promoter/cassette was used as an internal control for transfection efficiency.…”

“…Supernatant containing total proteins was quantified and 80 μg of each sample were separated on 12% SDS-PAGE. Western blotting assays were carried out] Protein extracts from treated and untreated cells were obtained, quantified and analyzed by Western blot as reported46.…”

Rational drug design, synthesis, and biological evaluation of novel chiral tetrahydronaphthalene-fused spirooxindole as MDM2-CDK4 dual inhibitor against glioblastoma

“…Therefore, we focused on asymmetric synthesis of optically pure C3-spirooxindoles 75 , 76 , 77 , 78 . We started from hydronaphthalene 79 , 80 , 81 , 82 , 83 , 84 and spirooxindole 10 , 22 , 23 , 25 , 65 because they are privileged frameworks occurring in many anti-tumor natural products and pharmaceuticals. Combination of privileged frameworks can facilitate molecular diversity and discovery of lead compounds 85 , 86 .…”

<p>Free Fatty Acids Promote the Development of Prostate Cancer by Upregulating Peroxisome Proliferator-Activated Receptor Gamma</p>

“…For example: In colon cancer, cladosporol A, secondary metabolites from cladosporium tenuissimum characterized for their ability to control cell proliferation, inhibits proliferation of human colon cancer cells through a PPARγ-mediated modulation of gene expression. 39 Pioglitazone as a PPARγ agonist may inhibit growth and invasion of HCC cells via blockade of the RAGE signaling. 40 In esophageal cancer, rosiglitazone, an agonist of PPARγ, can inhibit the proliferation of esophageal cancer cells and promote their apoptosis.…”