Phorbol 12-Myristate 13-Acetate Induced Toxicity Study and the Role of Tangeretin in Abrogating HIF-1α-NF-κB Crosstalk In Vitro and In Vivo.

Phorbol 12-myristate 13-acetate (PMA) is a potent tumor promoter and highly inflammatory in nature. Here, we investigated the toxic effects of PMA on different model system. PMA (10 µg) caused chromosomal aberrations on the Allium cepa root tip and induced mitotic dysfunction. Similarly, PMA caused embryonic and larval deformities and a plummeted survivability rate on zebrafish embryo in a dose-dependent manner. Persistently, PMA treatment on immortalized human keratinocyte human keratinocyte (HaCaT) cells caused massive inflammatory rush at 4 h and a drop in cell survivability at 24 h. Concomitantly, we replicated a cutaneous inflammation similar to human psoriasis induced by PMA. Herein, we used tangeretin (TAN), as an antagonist to counteract the inflammatory response. Results from an in vivo experiment indicated that TAN (10 and 30 mg/kg) significantly inhibited PMA stimulated epidermal hyperplasia and intra-epidermal neutrophilic abscesses. In addition, its treatment effectively neutralized PMA induced elevated reactive oxygen species (ROS) generation on in vitro and in vivo systems, promoting antioxidant response. The association of hypoxia-inducible factor 1-alpha (HIF-1α)-nuclear factor kappa-light-chain-enhancer of activated b cells (NF-κB) crosstalk triggered by PMA enhanced PKCα-ERK1/2-NF-κB pathway; its activation was also significantly counteracted after TAN treatment. Conclusively, we demonstrated TAN inhibited the nuclear translocation of HIF-1α and NF-κB p65. Collectively, TAN treatment ameliorated PMA incited malignant inflammatory response by remodeling the cutaneous microenvironment.

Chebulinic acid attenuates glutamate-induced HT22 cell death by inhibiting oxidative stress, calcium influx and MAPKs phosphorylation.

Glutamate-induced excitotoxicity and oxidative stress is a major causative factor in neuronal cell death in acute brain injuries and chronic neurodegenerative diseases. The prevention of oxidative stress is a potential therapeutic strategy. Therefore, in the present study, we aimed to examine a potential therapeutic agent and its protective mechanism against glutamate-mediated cell death. We first found that chebulinic acid isolated from extracts of the fruit of Terminalia chebula prevented glutamate-induced HT22 cell death. Chebulinic acid significantly reduced intracellular reactive oxygen species (ROS) production and Ca2+ influx induced by glutamate. We further demonstrated that chebulinic acid significantly decreased the phosphorylation of mitogen-activated protein kinases (MAPKs), including ERK1/2, JNK, and p38, as well as inhibiting pro-apoptotic Bax and increasing anti-apoptotic Bcl-2 protein expression. Moreover, we demonstrated that chebulinic acid significantly reduced the apoptosis induced by glutamate in HT22 cells. In conclusion, our results in this study suggest that chebulinic acid is a potent protectant against glutamate-induced neuronal cell death via inhibiting ROS production, Ca2+ influx, and phosphorylation of MAPKs, as well as reducing the ratio of Bax to Bcl-2, which contribute to oxidative stress-mediated neuronal cell death.

Irinotecan, continuous 5-fluorouracil, and low dose of leucovorin (modified FOLFIRI) as first line of therapy in recurrent or metastatic colorectal cancer.

BACKGROUND: Irinotecan, in combination with 5-fluorouracil (5-FU) and a high dose of leucovorin (LV), known as FOLFIRI regimen, has shown activity in recurrent or metastatic colorectal cancer. Therefore, we evaluated the efficacy and safety of irinotecan, 5-FU and a low dose of LV (modified FOLFIRI) as a first line of therapy for patients with relapsed or metastatic colorectal cancer. METHODS: Between January 2002 and October 2004, 44 patients with histologically confirmed recurrent or metastatic colorectal cancer were enrolled. The chemotherapy regimen schedule consisted of 180 mg/m2 of irinotecan being administered intravenously (i.v) on Day 1, 400 mg/m2 of 5-FU via i.v bolus with 600 mg/m2 of continuous infusion for 22 hrs on both Day 1 and 2, and 20 mg/m2 of leucovorin on both Day 1 and 2 , repeated every two weeks. RESULTS: The overall response rate was 47.8%. Of the 40 evaluated patients, one had CR (2.3%) and 20 had PR (46.5%). Toxicities were mild and easily manageable. Three patients experienced 23 episodes of Grade 3/4 leukopenia., Only one patient developed Grade 3/4 diarrhea. None experienced Grade 3/4 thrombocytopenia. CONCLUSION: Modified FOLFIRI with a low dose of LV is an effective and tolerable regimen for patients with recurrent or metastatic colorectal cancer.