Amorfrutin C Induces Apoptosis and Inhibits Proliferation in Colon Cancer Cells through Targeting Mitochondria

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• 作者：Christopher Weidner ; Morten Rousseau ; Robert J. Micikas ; Cornelius Fischer ; Annabell Plauth ; Sylvia J. Wowro ; Karsten Siems ; Gregor Hetterling ; Magdalena Kliem ; Frank C. Schroeder ; Sascha Sauer
• 刊名：Journal of Natural Products
• 出版年：2016
• 出版时间：January 22, 2016
• 年：2016
• 卷：79
• 期：1
• 页码：2-12
• 全文大小：664K
• ISSN：1520-6025

文摘

A known (1) and a structurally related new natural product (2), both belonging to the amorfrutin benzoic acid class, were isolated from the roots of Glycyrrhiza foetida. Compound 1 (amorfrutin B) is an efficient agonist of the nuclear peroxisome proliferator activated receptor (PPAR) gamma and of other PPAR subtypes. Compound 2 (amorfrutin C) showed comparably lower PPAR activation potential. Amorfrutin C exhibited striking antiproliferative effects for human colorectal cancer cells (HT-29 and T84), prostate cancer (PC-3), and breast cancer (MCF7) cells (IC₅₀ values ranging from 8 to 16 μM in these cancer cell lines). Notably, amorfrutin C (2) showed less potent antiproliferative effects in primary colon cells. For HT-29 cells, compound 2 induced G0/G1 cell cycle arrest and modulated protein expression of key cell cycle modulators. Amorfrutin C further induced apoptotic events in HT-29 cells, including caspase activation, DNA fragmentation, PARP cleavage, phosphatidylserine externalization, and formation of reactive oxygen species. Mechanistic studies revealed that 2 disrupts the mitochondrial integrity by depolarization of the mitochondrial membrane (IC₅₀ 0.6 μM) and permanent opening of the mitochondrial permeability transition pore, leading to increased mitochondrial oxygen consumption and extracellular acidification. Structure–activity-relationship experiments revealed the carboxylic acid and the hydroxy group residues of 2 as fundamental structural requirements for inducing these apoptotic effects. Synergy analyses demonstrated stimulation of the death receptor signaling pathway. Taken together, amorfrutin C (2) represents a promising lead for the development of anticancer drugs.