vulpinic-acid and Neoplasms

The oxidative pentose phosphate pathway (PPP) contributes to tumour growth, but the precise contribution of 6-phosphogluconate dehydrogenase (6PGD), the third enzyme in this pathway, to tumorigenesis remains unclear. We found that suppression of 6PGD decreased lipogenesis and RNA biosynthesis and elevated ROS levels in cancer cells, attenuating cell proliferation and tumour growth. 6PGD-mediated production of ribulose-5-phosphate (Ru-5-P) inhibits AMPK activation by disrupting the active LKB1 complex, thereby activating acetyl-CoA carboxylase 1 and lipogenesis. Ru-5-P and NADPH are thought to be precursors in RNA biosynthesis and lipogenesis, respectively; thus, our findings provide an additional link between the oxidative PPP and lipogenesis through Ru-5-P-dependent inhibition of LKB1-AMPK signalling. Moreover, we identified and developed 6PGD inhibitors, physcion and its derivative S3, that effectively inhibited 6PGD, cancer cell proliferation and tumour growth in nude mice xenografts without obvious toxicity, suggesting that 6PGD could be an anticancer target.

Topics: AMP-Activated Protein Kinase Kinases; AMP-Activated Protein Kinases; Humans; Lipogenesis; Neoplasms; Oxidative Stress; Pentose Phosphate Pathway; Phosphogluconate Dehydrogenase; Protein Serine-Threonine Kinases; Ribulosephosphates; Signal Transduction

Five compounds representative of major structural classes of lichen polyketides, VIZ. (+)-usnic (1), salazinic (2), vulpinic (3), gyrophoric (4), and evernic acids (5), were investigated for their ability to affect cell proliferation or wound healing, two functional targets of relevance for research on cancer or tissue regeneration. The experiments were carried out on MM98 malignant mesothelioma cells, A431 vulvar carcinoma cells, and HaCaT keratinocytes. The NRU and CV cytotoxicity assays showed high toxicity for (+)-usnic acid, intermediate toxicity for vulpinic acid, and low toxicity for salazinic, gyrophoric and evernic acids. Scratch wounding experiments on HaCaT monolayers, in the presence of subtoxic doses of lichen compounds, showed strong wound closure effects by (+)-usnic and gyrophoric acid, an intermediate effect by vulpinic and salazinic acids, and no effect by evernic acid. A combination of (+)-usnic and gyrophoric acids gave a further increase in the wound closure rates. The results of a cell migration test correlated with the wound healing data. In conclusion, (+)-usnic acid might be a particularly interesting compound for the prevention of hyperproliferation syndromes, while (+)-usnic and gyrophoric acids qualify as interesting leads in the promotion of tissue regeneration.

Topics: Antineoplastic Agents, Phytogenic; Benzoates; Benzofurans; Cell Line, Tumor; Cell Proliferation; Female; Furans; Humans; Hydroxybenzoates; Keratinocytes; Lactones; Lichens; Neoplasms; Phenylacetates; Phytotherapy; Plant Extracts; Salicylates; Wound Healing