The effect of resveratrol and its methylthio-derivatives on EGFR and Stat3 activation in human HaCaT and A431 cells

Epidermal growth factor receptor (EGFR) interacting with Stat3 is considered to be an attractive therapeutic target. In the current study, we investigated the effect of resveratrol and its two 4′-methylthio-trans-stilbene derivatives (3-M-4′-MTS; S2) (3,5-DM-4″-MTS; S5) on EGFR and Stat3 activation in human immortalized HaCaT keratinocytes and epidermoid carcinoma A431 cells. In the HaCaT cells both derivatives, similarly as resveratrol, decreased the total level of the EGFR receptor. In the A431 cells, resveratrol in the higher dose significantly (p < 0.05) reduced Y1173 and Y1068 EGFR residue phosphorylation, while S2 affected only the phosphorylation of the Y1068 residue. In this cell line, resveratrol in both tested doses and the S2 derivative in the lower concentration significantly diminished Stat3 binding capacity to the DNA consensus site. The effect of the tested compounds on Stat3 activation in HaCaT cells was only slightly affected. These results indicate that methylthiostilbenes are not more potent modulators of the EGFR/Stat3 complex than resveratrol and that introducing an additional methoxy group makes them less effective

THE EFFECT OF NICLOSAMIDE ON THE HEAD AND NECK CARCINOMA CELLS SURVIVAL AND THE EXPRESSION OF WNT/β-CATENIN SIGNALING AND GLYCOLYSIS PATHWAY COMPONENTS

The aim of this study was to evaluate the effect of niclosamide, an antihelminthic drug recently identified as potential anti-cancer agent, on head and neck squamous carcinoma cells (HNSCC) viability, cell cycle distribution and apoptosis. The expression of key components of Wnt (CTNNB1, GSK-3β, CCND1, c-MYC, MMP7, BIRC5, Axin2) and glycolysis (GLUT1, MCT1, HK2, PFKM, PKM2, PDHA1, PDK1, LDHA) pathways was also examined to assess possible involvement in niclosamide anti-carcinogenic activity. HNSCC cells (FaDu, BICR6, H314 lines) were used in the research. Niclosamide treatment affected hypopharyngeal FaDu cells to the most extent (IC50 = 0.40 µM), while H314 cells derived from the floor of mouth were the least sensitive (IC50 = 0.94 µM). In FaDu cells the increased percentage of the cells in the S phase was observed along with the induction of apoptosis. Treatment with niclosamide in FaDu cells reduced the expression of MMP7 and the majority of glycolytic genes except increased LDHA. These results indicate that niclosamide is efficient inhibitor of HNSCC cells viability, however this effect depends on the cell type. In FaDu cells, the most sensitive to its anti-proliferative effect and prone to cell cycle arrest and apoptosis, this effect might be related to slightly modulation of canonical Wnt signaling and increased expression of LDHA

Effect of natural phenols on the catalytic activity of cytochrome P450 2E1

The effect of protocatechuic acid, tannic acid and trans-resveratrol on the activity of p-nitrophenol hydroxylase (PNPH), an enzymatic marker of CYP2E1, was examined in liver microsomes from acetone induced mice. trans-Resveratrol was found to be the most potent inhibitor (IC50 = 18.5 ± 0.4 mM) of PNPH, while protocatechuic acid had no effect on the enzyme activity. Tannic acid with IC50 = 29.6 ± 3.3 mM showed mixed- and trans-resveratrol competitive inhibition kinetics (Ki = 1 mM and 2.1 mM, respectively). Moreover, trans-resveratrol produced a NADPH-dependent loss of PNPH activity, suggesting mechanism-based CYP2E1 inactivation. These results indicate that trans-resveratrol and tannic acid may modulate cytochrome P450 2E1 and influence the metabolic activation of xenobiotics mediated by this P450 isoform

Phytochemical Combinations Modulate the Activation of Nrf2 and Expression of SOD<em> </em>in Pancreatic Cancer Cells More Efficiently Than Single Plant Components

Pancreatic adenocarcinoma mainly occurs in elderly people. Thus, the management of pancreatic cancer in the aging population is becoming increasingly relevant. In this preliminary study we evaluated the effect of selected phytochemicals and their combinations on the expression and activation of Nrf2 transcription factor in the human pancreatic cancer cell line MIA-Pa-Ca-2. Treatment for 24 h with xanthohumol (X), resveratrol (RES), indole-3-carbinol (I3C) or phenethyl isothiocyanate (PEITC) had no effect on the expression and activation of Nrf2, or the expression of the SOD gene controlled by Nrf2. However, combinations of these phytochemicals significantly increased Nrf2 activation and subsequently the expression of SOD. The most efficient were the mixtures of resveratrol and glucosinolates degradation products, I3C and PEITC. These results indicate that combinations of phytochemicals resembling that occurring in natural diets may efficiently modulate the signaling pathways, whose proper function is important for pancreatic cancer prophylaxis or improving the results of conventional therapy

Indomethacin and Diclofenac Hybrids with Oleanolic Acid Oximes Modulate Key Signaling Pathways in Pancreatic Cancer Cells

Our earlier studies showed that coupling nonsteroidal anti-inflammatory drugs (NSAIDs) with oleanolic acid derivatives increased their anti-inflammatory activity in human hepatoma cells. The aim of this study was to evaluate their effect on the signaling pathways involved in inflammation processes in human pancreatic cancer (PC) cells. Cultured PSN-1 cells were exposed for 24 h (30 µM) to OA oxime (OAO) derivatives substituted with benzyl or morpholide groups and their conjugates with indomethacin (IND) or diclofenac (DCL). The activation of NF-κB and Nrf2 was assessed by the evaluation of the translocation of their active forms into the nucleus and their binding to specific DNA sequences via the ELISA assay. The expression of NF-κB and Nrf2 target genes was evaluated by R-T PCR and Western blot analysis. The conjugation of IND or DCL with OAO derivatives increased cytotoxicity and their effect on the tested signaling pathways. The most effective compound was the DCL hybrid with OAO morpholide (4d). This compound significantly reduced the activation and expression of NF-κB and enhanced the activation and expression of Nrf2. Increased expression of Nrf2 target genes led to reduced ROS production. Moreover, MAPKs and the related pathways were also affected. Therefore, conjugate 4d deserves more comprehensive studies as a potential PC therapeutic agent