Arctigenin induces apoptosis in colon cancer cells through ROS/p38MAPK pathway.

PURPOSE: In the current study the antiproliferative effect of arctigenin, plant lignin, was evaluated on human colon cancer cell line HT-29. Furthermore, attempts were made to explore the signaling mechanism which may be responsible for its effect. METHODS: Cell growth inhibition was assessed by MTT and LDH assays. Flow cytometric analysis was performed to determine cell arrest in the cell cycle phase and apoptosis. Furthermore, to confirm the apoptotic activity of arctigenin, caspase-9 and -3 activities analysis was performed. The levels of reactive oxygen species (ROS) and p38 mitogen activated protein kinase (MAPK) were investigated to determine their role in inducing apoptosis in arctigenin-treated HT-29 colon cancer cell line. RESULTS: MTT and LDH results demonstrated significant cell growth inhibitory effect of arctigenin on HT-29 cells in a dose-dependent manner. Furthermore, increase in cell number arrested at G2/M phase was observed in flow cytometric analysis upon arctigenin treatment. In addition, arctigenin increased the apoptotic ratio in a dose-dependent manner. The involvement of intrinsic apoptotic pathway was indicated by the activation of caspase-9 and -3. Moreover, increased ROS production, activation of p38 MAPK and changes in mitochondrial membrane potential (ΔΨm) also revealed the role of intrinsic apoptotic signaling pathway in cell growth inhibition after arctigenin exposure. CONCLUSION: Arctigenin induces apoptosis in HT-29 colon cancer cells by regulating ROS and p38 MAPK pathways.

Enhanced therapeutic efficacy and amelioration of cisplatin-induced nephrotoxicity by quercetin in 1,2-dimethyl hydrazine-induced colon cancer in rats.

OBJECTIVE: The aim of quercetin treatment in combination of cisplatin (CP)-induced nephrotoxicity as well on 1,2-dimethyl hydrazine (DMH)-induced colon cancer. MATERIALS AND METHODS: In this study, animals are exposed to DMH hydrochloride to induce colon cancer. In these groups, nephrotoxicity was assessed with the help of blood urea nitrogen, urea, and creatinine. The antitumor activity of quercetin and CP assessed with the help of number of aberrant crypts and foci formation. Tumor size in different treatment group determined with the help of vernier caliper. RESULTS: CP is one of the most widely used antineoplastic drugs against colon cancer, but it has a major dose-limiting drawbacks of causing nephrotoxicity. Therefore, there is a need for a novel therapeutic regimen which will reduce the nephrotoxicity and enhance the anticancer activity of CP. The protective effect of quercetin on CP-induced nephrotoxicity is well-known. Moreover, quercetin is proven to have antitumor activity in colon cancer. Keeping all the facts in view, this study was conceived to evaluate the role of quercetin on therapeutic efficacy and nephrotoxicity of CP in DMH-induced colon cancer in male Sprague-Dawley rats. Treatment of quercetin with CP (7.5 mg/kg) prevents the CP-induced nephrotoxicity along with enhance the anticancer activity confirmed by the reduction of aberrant crypt foci number. Treatment of CP and quercetin alone leads to significant increase in the anticancer activity as compared to control colon tumor rats. CONCLUSION: In DMH-induced colon cancer model, combination of quercetin and CP ameliorates CP-induced nephrotoxicity as well as enhanced antitumor activity.

CpG oligodeoxynucleotides enhance chemosensitivity of 5-fluorouracil in HepG2 human hepatoma cells via downregulation of the antiapoptotic factors survivin and livin.

BACKGROUND: Recent studies indicated that a synthetic oligonucleotide containing un-methylated CpG oligodeoxynucleotides (CpG-ODN) has a potential function for cancer therapy. In this study, we evaluated the chemosensitizing effects of CpG-ODN in 5-fluorouracil (5-FU)-treated HepG2 human hepatoma cells. METHODS: Cell viability assay were utilized to evaluate the direct cytotoxicity of CpG-ODN in the presence or absence of 5-FU in HepG2 cells, and apoptosis as well as cell-cycle was examined by flow cytometry analysis. The mRNA expression of Bcl-2, Livin and Survivin within HepG2 cells treated with CpG-ODN and/or 5-FU were analyzed by Real Time PCR assay in vitro. RESULTS: CpG-ODN in combination with 5-FU could decrease cell viability, increase apoptosis and further induce HepG2 cells cycle arrest at S phase when compared with CpG-ODN or 5-FU. CpG-ODN or 5-FU could down-regulate the mRNA expression of Bcl-2 within HepG2 cells. The mRNA expression of Livin and Survivin decreased in cells treated with CpG-ODN alone but increased in cells treated with 5-FU alone. However, CpG-ODN in combination with 5-FU could down-regulate the mRNA expression of Livin and Survivin within HepG2 cells. CONCLUSIONS: Our finding demonstrated that CpG-ODN enhanced the chemosentivity of 5-FU in HepG2 human hepatoma cells at least in part by down-regulating the expression of Livin and Survivin, leading to apoptosis and further inducing cell cycle arrest at S phase. Therefore, CpG-ODN may be a potential candidate as chemosensitizer for human hepatocellular carcinoma.