Luteolin and Gemcitabine Protect Against Pancreatic Cancer in an Orthotopic Mouse Model.

OBJECTIVE: This study aimed to evaluate the ability of luteolin (Lut), gemcitabine (Gem), and their combination (Lut + Gem) to prevent the growth of pancreatic tumors in vivo. METHODS: The antitumor effect of intraperitoneally administered Lut, Gem, and Lut + Gem was evaluated using an orthotopic mouse model for 6 weeks. Tumor growth after injection of human pancreatic cancer cells was assessed by measuring pancreatic tumor mass. The mechanism of action of antitumor effect was assessed by immunohistochemistry and Western blot procedures. RESULTS: Luteolin + Gem significantly lowered (P = 0.048) the pancreatic tumor mass compared with control. Luteolin, Gem, and Lut + Gem significantly reduced the proliferating cell nuclear antigen expression (25%, 37%, and 37%, respectively). Luteolin + Gem treatment led to a significant reduction in the expressions of K-ras (46%, P = 0.0006), GSK-3ß (34%, P = 0.014), P(Tyr216)GSK-3ß (16%, P = 0.033), P(Ser311)NF-κB p65 (27%, P = 0.036), and bcl-2/bax ratio (68%, P = 0.006) while significantly increasing the expressions of cytochrome c (44%, P = 0.035) and caspase 3 (417%, P = 0.003). CONCLUSIONS: Luteolin + Gem promoted apoptotic cell death in pancreatic tumor cells in vivo through inhibition of the K-ras/GSK-3ß/NF-κB signaling pathway, leading to a reduction in the Bcl-2/Bax ratio, release of cytochrome c, and activation of caspase 3.

NMR-based metabolomic investigation of bioactivity of chemical constituents in black raspberry (Rubus occidentalis L.) fruit extracts.

Black raspberry (Rubus occidentalis L.) (BR) fruit extracts with differing compound profiles have shown variable antiproliferative activities against HT-29 colon cancer cell lines. This study used partial least-squares (PLS) regression analysis to develop a high-resolution (1)H NMR-based multivariate statistical model for discerning the biological activity of BR constituents. This model identified specific bioactive compounds and ascertained their relative contribution against cancer cell proliferation. Cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were the predominant contributors to the extract bioactivity, but salicylic acid derivatives (e.g., salicylic acid glucosyl ester), quercetin 3-glucoside, quercetin 3-rutinoside, p-coumaric acid, epicatechin, methyl ellagic acid derivatives (e.g., methyl ellagic acetyl pentose), and citric acid derivatives also contributed significantly to the antiproliferative activity of the berry extracts. This approach enabled the identification of new bioactive components in BR fruits and demonstrates the utility of the method for assessing chemopreventive compounds in foods and food products.

Interactions between dietary flavonoids apigenin or luteolin and chemotherapeutic drugs to potentiate anti-proliferative effect on human pancreatic cancer cells, in vitro.

The objectives were to assess the potential of dietary flavonoids apigenin (Api) and luteolin (Lut) to enhance the anti-proliferative effects of chemotherapeutic drugs on BxPC-3 human pancreatic cancer cells and to investigate the potential molecular mechanism of action. Simultaneous treatment or pretreatment (0, 6, 24 and 42 h) of flavonoids and chemotherapeutic drugs at various concentrations (0-50 µM) were assessed using the MTS cell proliferation assay. Simultaneous treatment with either flavonoid (13, 25 or 50 µM) and chemotherapeutic drugs 5-fluorouracil (5-FU, 50 µM) or gemcitabine (Gem, 10 µM) for 60 h resulted in mostly less-than-additive effects (p<0.05). Pretreatment for 24h with 13 µM of either Api or Lut, followed by Gem for 36 h was optimal to inhibit cell proliferation. Pretreatment of cells with 11-19 µM of either flavonoid for 24h resulted in 59-73% growth inhibition when followed by Gem (10 µM, 36 h). Lut (15 µM, 24h) pretreatment followed by Gem (10 µM, 36 h), significantly decreased protein expression of nuclear GSK-3ß and NF-κB p65 and increased pro-apoptotic cytosolic cytochrome c. Pretreatment of BxPC-3 human pancreatic cancer cells with low concentrations of Api or Lut effectively aid in the anti-proliferative activity of chemotherapeutic drugs.

Flavonoid apigenin modified gene expression associated with inflammation and cancer and induced apoptosis in human pancreatic cancer cells through inhibition of GSK-3ß/NF-κB signaling cascade.

SCOPE: The objective was to examine the inhibitory effects of citrus fruit bioactive compounds on BxPC-3 and PANC-1 human pancreatic cancer cells, focusing on the antiproliferative mechanism of action of the flavonoid apigenin related to the glycogen synthase kinase-3ß/nuclear factor kappa B signaling pathway. METHODS AND RESULTS: Flavonoids, limonoids, phenolic acids, and ascorbic acid were tested for cytotoxic effects on BxPC-3 and PANC-1 cells; apigenin was the most potent (IC50 = 23 and 12 µM for 24 and 48 h for BxPC-3 and IC50 = 71 and 41 µM for 24 and 48 h for PANC-1). Apigenin induced pancreatic cell death through inhibition of the glycogen synthase kinase-3ß/nuclear factor kappa B signaling pathway. Apigenin arrested cell cycle at G2 /M phase (36 and 32% at 50 µM for BxPC-3 and PANC-1, respectively) with concomitant decrease in the expression of cyclin B1. Apigenin activated the mitochondrial pathway of apoptosis (44 and 14% at 50 µM for BxPC-3 and PANC-1, respectively) and modified the expression of apoptotic proteins. Apigenin highly upregulated the expression of cytokine genes IL17F (114.2-fold), LTA (33.1-fold), IL17C (23.2-fold), IL17A (11.3-fold), and IFNB1 (8.9-fold) in BxPC-3 cells, which potentially contributed to the anticancer properties. CONCLUSION: Flavonoids have a protective role in pancreatic cancer tumorigenesis.

Effect of black raspberry ( Rubus occidentalis L.) extract variation conditioned by cultivar, production site, and fruit maturity stage on colon cancer cell proliferation.

Black raspberries have been shown to inhibit multiple stages of oral, esophageal, and colon cancer. The objective of this study was to evaluate how black raspberry extract variability conditioned by horticultural factors affected the antiproliferative activity of 75 black raspberry extracts using an in vitro colon cancer cell model. HT-29 cells grown in 96-well plates were treated with freeze-dried extracts at 0.6 and 1.2 mg of extract/mL of medium. Percent cell growth inhibition for each concentration of the extracts was determined using the sulforhodamine B assay. All extracts significantly inhibited the growth of HT-29 colon cancer cells in a dose-dependent manner. Cell proliferation was significantly influenced by cultivar, production site, and stage of maturity. The lack of correlation between growth inhibition and extract total phenolic and total monomeric anthocyanin assays suggested horticultural parameters influence bioactivity in a complex manner.

Citrus flavonoids luteolin, apigenin, and quercetin inhibit glycogen synthase kinase-3ß enzymatic activity by lowering the interaction energy within the binding cavity.

Pancreatic cancer studies have shown that inhibition of glycogen synthase kinase-3ß (GSK-3ß) leads to decreased cancer cell proliferation and survival by abrogating nuclear factor κB (NFκB) activity. In this investigation, various citrus compounds, including flavonoids, phenolic acids, and limonoids, were individually investigated for their inhibitory effects on GSK-3ß by using a luminescence assay. Of the 22 citrus compounds tested, the flavonoids luteolin, apigenin, and quercetin had the highest inhibitory effects on GSK-3ß, with 50% inhibitory values of 1.5, 1.9, and 2.0 µM, respectively. Molecular dockings were then performed to determine the potential interactions of each citrus flavonoid with GSK-3ß. Luteolin, apigenin, and quercetin were predicted to fit within the binding pocket of GSK-3ß with low interaction energies (-76.4, -76.1, and -84.6 kcal·mol(-1), respectively) and low complex energies (-718.1, -688.1, and -719.7 kcal·mol(-1), respectively). Our results indicate that several citrus flavonoids inhibit GSK-3ß activity and suggest that these have potential to suppress the growth of pancreatic tumors.