ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of tBHQ and sulforaphane on the protein expression in Nrf2-ARE signaling pathway of Caco2 cells.</p><p><b>METHODS</b>Human colorectal carcinoma Caco2 cells were treated with 20 micromol/L tBHQ and 5 micromol/L sulforaphane (SFN) respectively. Real time PCR, Western blotting and immunoflourescence staining (IF) were performed to measure the target gene expression.</p><p><b>RESULTS</b>Nrf2, AKR1C1 and NQO1 protein expressions were increased time-dependently in Caco2 cells after treatment with tBHQ and SFN. Time-course experiments showed that tBHQ and SFN increased the accumulation of Nrf2, and concomitantly increased the protein levels of AKR1C1 and NQO1. Real-time PCR and Western blotting showed that tBHQ and SFN significantly increased the expression of Nrf2 at 8h after the treatment, and AKR1C1 and NQO1 at 16 h. Confocal microscopy technique showed that Nrf2 accumulated in the nucleus at 6-8 h after treatment with tBHQ. After 1 h treatment with tBHQ the nuclear Nrf2 maintained at elevated level for at least 4 h with tBHQ withdrawn.</p><p><b>CONCLUSION</b>tBHQ and SFN induced nuclear accumulation of Nrf2 and activated Nrf2-dependent regulation of ARE-mediated gene expression in Caco2 cells. In addition, the results provide experimental evidence for choosing the dose and frequency of the inducer in cancer chemoprevention study and in developing inhibitors of Nrf2-ARE signaling pathway.</p>
Subject(s)
Humans , Anticarcinogenic Agents , Pharmacology , Antioxidants , Metabolism , Pharmacology , Caco-2 Cells , Calcium-Transporting ATPases , Hydroquinones , Pharmacology , Isothiocyanates , NF-E2-Related Factor 2 , Genetics , Metabolism , Physiology , Oxidative Stress , Genetics , Physiology , Response Elements , Physiology , Signal Transduction , Thiocyanates , PharmacologyABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of Luteolin alone or combination with chemotherapentic drugs on the cytoxicity of cancer cells.</p><p><b>METHODS</b>Cultured A549, Hela, MCF-7, AGS, MGC-803, Caco2 and HepG2 cells were treated with Luteolin or the combination of Luteolin with other chemotherapeutic agents (Bexarotene, Cisplatin and Bleomycin). Cell viability was measured by MTS assay and IC(50) was calculated.</p><p><b>RESULTS</b>The IC(50) of Bexarotene to Hela cells was 2 micromol/L, but with the combination of 5 micromol/L of Luteolin that reduced to 0.2 micromol/L. However, the combination of Bexarotene and Luteolin did not show significant benefit in MGC-803, HepG2 cells, Caco2 and MCF-7 cells. The IC(50) of Cisplatin to Hela cells was over 30 micromol/L,but it decreased to 3 micromol/L in the presence of 5 micromol/L Luteolin; Luteolin also sensitized Cisplatin in MGC-803, HepG2 and A549 cells studied. The IC(50) of Bleomycin to Hela cells was over 100 micromol/L, but it was about 1 micromol/L in the presence of 5 micromol/L Luteolin. A549 cells were resistant to Bleomycin with an IC(50) of 100 micromol/L, 10 micromol/L Luteolin greatly enhanced the cytotoxicity of Bleomycin to the cells with the IC(50) of about 10 micromol/L. The inhibitions of MGC-803, HepG2, A549 and AGS cells didn't change by combination of Luteolin.</p><p><b>CONCLUSION</b>Low concentration of Luteolin has little toxic effect on the cancer cell lines tested in the study, but it can sensitize chemotherapeutic drugs in various cancer cell lines.</p>