Research progress on MKP-1 in tumor drug resistance / 浙江大学学报·医学版

The main obstacle for chemotherapy is tumor drug resistance. Studying the mechanisms of drug resistance and reversing drug resistance is the key to improve the effectiveness of chemotherapy. It has been reported that MKP-1 plays an important role in tumor drug resistance. MKP-1, as a negative regulator of MAPKs, is involved in the MAPKs mediated drug resistance and is regulated by ERK and p38 signaling pathways.However, the relationship between MKP-1 and other drug resistance-related signaling pathways is not clear and requires further investigation.

Nrf2 as a chemoprevention target in gastrointestinal carcinoma / 浙江大学学报·医学版

Gastrointestinal tract carcinoma is one of the leading causes of cancer-related death in China. Chemoprevention has been considered as a potential approach to control this type of disease. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a redox-sensitive transcription factor that protects cells from oxidative/electrophilic stresses by activating the expression of a battery of cytoprotective genes through the antioxidant response element (ARE). Recently, Nrf2 has emerged as a novel target for chemoprevention. Several natural or synthetic chemicals, which activate Nrf2/ARE signaling pathway, have showed effect in animal models, and promises in many ongoing clinical trials. This review summarizes the recent findings on the regulation of Nrf2/ARE signaling pathway, and the developments in both preclinical and clinical studies.

Anti-proliferation and chemo-sensitization effects of apigenin on human lung cancer cells / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the antitumor effect of apigenin on human lung cancer cells.</p><p><b>METHODS</b>The anti-proliferation and sensitization effects of apigenin on human lung cancer cells was accessed by counting cells after Trypan blue staining and MTS assay.</p><p><b>RESULTS</b>(1) Apigenin significantly suppressed the proliferation of four types of human lung cancer cells (A549:P=0.041, H460:P=0.050, LTEP-a2:P=0.039, H292:P=0.016); (2) Apigenin significantly increased the susceptibility of human lung cancer cells to antitumor drugs (P<0.05 or P<0.01) in a synergistic way (almost all of the combination index values are less than 1).</p><p><b>CONCLUSION</b>Apigenin widely inhibits cell proliferation of various lung cancer cell lines in a dose-dependent manner and the combination treatment of apigenin and antitumor drugs is very effective in human lung cancer cells, and Nrf2-ARE pathway may contribute to the mechanism.</p>

Nrf2 down-regulated cell line H460-N5 with Keap1 over-expression increased sensitivity to anti-cancer drugs / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To maked a Nrf2 down-regulated cell line by over-expressing Keap1 in H460 cells to study the role of Nrf2 in drug resistance.</p><p><b>METHODS</b>Transfecting H460 cells with mKeap1-pEGFP and screenig for Keap1 expressing clones by Western blotting with antibodies against Nrf2, HO-1, NQO1 and AKR1C. The cell line with Keap1 over-expression was further confirmed by real-time PCR. The cytotoxicity of H460-N5 to anti-cancer drugs was evaluated by MTS assay.</p><p><b>RESULT</b>MTS assay results showed the enhanced cytotoxicity of anticancer drugs (Oxaliplatin, Doxorubicin and Etopside) to the H460 cell line with keap1 overexpression compared to the control cell line. In H460-N0 cells, the IC(50) values of Oxaliplation and Etopside were 93 micromol/L and 100 micromol/L respectively whereas the IC(50) values of the two drugs were 42 micromol/L and 30 micromol/L correspondingly in H460-N5 cells. A Nrf2 down-regulated cell line H460-N5 and a control cell line with GFP over-expression have been identified.Down-regulation of Nrf2 enhanced the cytotoxicity of Oxaliplatin, Doxorubicin and Etopside. The IC(50) value of Doxorubicin to H460-N0 cell was above 3 mg/L, but that to H460-N5 cell was about 2 mg/L.</p><p><b>CONCLUSION</b>A Nrf2 down-regulated cell line H460-N5 and a control cell line with GFP over-expression have been identified. Down-regulation of Nrf2 enhanced the cytotoxicity of Oxaliplatin, Doxorubicin and Etopside.</p>

Down-regulation of Nrf2 enhances the cytotoxicity of Oxaliplatin to H460 cells / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To establish a stable H460 cell line with Nrf2 down-regulation to study the role of Nrf2 in Oxaliplatin resistance.</p><p><b>METHODS</b>Nrf2 down-regulated H460 cell line was obtained by transfecting cells with pRS-hNrf2 and followed by screening for Nrf2 expression by Western blotting. The cell lines were further characterized by analysing cellular GSH levels and cytotoxicity to anti-cancer drugs with MTS.</p><p><b>RESULT</b>Nrf2 down-regulated H460 cell lines were established successfully. Cellular GSH level reduced significantly in the H460-C9 and H460-C13 compared to control cells (P(C9)= 0.00249, P(C13)= 0.03944). Down-regulation of Nrf2 in H460 sensitized the anti-cancer effect of Oxaliplatin and Doxorubicin.</p><p><b>CONCLUSION</b>Nrf2 plays an important role in drug resistance. Down regulation of Nrf2 in H460 cell enhances cytotoxicity of Oxaliplatin.</p>

Effect of tBHQ and sulforaphane on Nrf2-ARE signaling pathway of Caco2 cells / 浙江大学学报·医学版

<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>

Effect of DRB/alpha-Amanitin on localization of Nrf2 in A549 cells / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To investigate the effects of transcriptional inhibitors 5, 6-dichloro-1-b-D-ribofuranosylbenzimidazole (DRB) and alpha-Amanitin on the localization of Nrf2 in the nucleus.</p><p><b>METHODS</b>A549 cells were treated with DRB (50 mg/L) or alpha-Amanitin (2.5 mg/L)for 1 h and 6 h in serum-free medium, respectively. The expressions of Nrf2, HO-1, NQO1 and AKR1C were detected by Western blotting analysis. The localization of Nrf2 was determined by laser scanning confocal microscopy after cells were treated with either DRB or agr:-Amanitin for 1 h.</p><p><b>RESULTS</b>The expressions of Nrf2 and Nrf2-ARE gene batteries HO-1, AKR1C and NQO1 were decreased after 6 h treated with either DRB or alpha-Amanitin. The expression of SC35 was up-regulated but RNA Pol II was down-regulated; Y12 and NPC did not significantly change. The localization of Nrf2 in the cell nucleus did not change significantly.</p><p><b>CONCLUSION</b>DRB and alpha-Amanitin can down-regulate the expression of Nrf2 and its targeting proteins HO-1, AKR1C and NQO1, but may have no effect on the localization of Nrf2.</p>

Effect of Luteolin and its combination with chemotherapeutic drugs on cytotoxicity of cancer cells / 浙江大学学报·医学版

<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>