Multifactorial anticancer effects of digalloyl-resveratrol encompass apoptosis, cell-cycle arrest, and inhibition of lymphendothelial gap formation in vitro

Abstract

BACKGROUND: Digalloyl-resveratrol (di-GA) is a synthetic compound aimed to combine the biological effects of the plant polyhydroxy phenols gallic acid and resveratrol, which are both radical scavengers and cyclooxygenase inhibitors exhibiting anticancer activity. Their broad spectrum of activities may probably be due to adjacent free hydroxyl groups. METHODS: Protein activation and expression were analysed by western blotting, deoxyribonucleoside triphosphate levels by HPLC, ribonucleotide reductase activity by 14 C-cytidine incorporation into nascent DNA and cell-cycle distribution by FACS. Apoptosis was measured by Hoechst 33258/propidium iodide double staining of nuclear chromatin and the formation of gaps into the lymphendothelial barrier in a three-dimensional co-culture model consisting of MCF-7 tumour cell spheroids and human lymphendothelial monolayers. RESULTS: In HL-60 leukaemia cells, di-GA activated caspase 3 and dose-dependently induced apoptosis. It further inhibited cell-cycle progression in the G1 phase by four different mechanisms: rapid downregulation of cyclin D1, induction of Chk2 with simultaneous downregulation of Cdc25A, induction of the Cdk-inhibitor p21 Cip/Waf and inhibition of ribonucleotide reductase activity resulting in reduced dCTP and dTTP levels. Furthermore, di-GA inhibited the generation of lymphendothelial gaps by cancer cell spheroidsecreted lipoxygenase metabolites. Lymphendothelial gaps, adjacent to tumour bulks, can be considered as gates facilitating metastatic spread. CONCLUSION: These data show that di-GA exhibits three distinct anticancer activities: induction of apoptosis, cell-cycle arrest and disruption of cancer cell-induced lymphendothelial disintegration.

Effects of Scrophularia extracts on tumor cell proliferation, death and intravasation through lymphoendothelial cell barriers

“…Asterisks indicate significance compared to untreated control (p<0.05) and error bars indicate ± SD. pro-apoptotic properties of different Scrophularia species, and beyond that we show that S. lucida inhibits LEC-CCID formation by co-cultivated MCF-7 cancer cell spheroids (14,17) and inhibited NF-κB activity. Recently we were able to demonstrate that NF-κB activity contributed to LEC-CCID formation through inhibition of VE-cadherin expression and loss of intraspecific LEC adhesion (16).…”

“…They were shown to perform inhibitory effects on enzymes of the arachidonate cascade (COX-1, COX-2) and significant reduction of LPS-induced TNF-α production without relevant effects on the ALOX5 pathway. Treating LEC monolayers with 1 µM synthetic 12(S)-HETE, a metabolite of arachidonic acid generated by ALOX12/15, caused the phosphorylation of MLC2 (16) indicating that 12(S)-HETE induced the motility of LECs thereby provoking an early step of metastasis (15,17). This observation is also consistent with an inflammatory process, which is accompanied by the acquisition of a mobile phenotype of the affected cells reflecting 'epithelial to mesenchymal transition' [EMT; (57)].…”

“…9) which are induced by exudates [i.e., 12(S)-hydoxyeicosatetraenoic acid] of MCF-7 cancer cell spheroids. CCIDs can be considered as entry gates for tumour cells and are directly responsible for lymph node-and distant metastases (15)(16)(17). The extract of S. floribunda did not prevent CCID formation but affected the viability of LECs and because of the toxic effect of 1 mg/ml MeOH extract to LECs, the precise effect on CCID formation could not be evaluated.…”

“…MCF-7 cell spheroids (3,000 cells/spheroid) were transferred to the 24-well plate containing LEC monolayers. After four hours of incubating the MCF-7 spheroids-LEC monolayer co-cultures, the CCID sizes in the LEC monolayer underneath the MCF-7 spheroids were photographed using an Axiovert (Zeiss, Jena, Germany) fluorescence microscope to visualise cytotracker (green)-stained LECs underneath the spheroids (17). Gap areas were calculated with the Axiovision Re.…”

The dichloromethane extract of the ethnomedicinal plant Neurolaena lobata inhibits NPM/ALK expression which is causal for anaplastic large cell lymphomagenesis

“…In search of novel cancer and lymphoma therapies we tested traditional healing plants and purified plant compounds regarding their anti-neoplastic properties (37)(38)(39)(40)(41)(42)(43)(44)(45)(46). The rationale for plant selection was their ethno-pharmaceutical use against chronic inflammation or severe skin defects (4).…”