Gleevec induces apoptosis in K562 cells through activating caspase-3 / 药学学报

The present study is to elucidate the mechanisms underlying Gleevec-induced apoptosis of chronic myeloid leukemia (CML) K562 cells in vitro. The apoptotic cell death and cell cycle distribution after Gleevec treatment and the effect of PDCD4 siRNA on Gleevec-induced apoptosis of K562 cells were analyzed by flow cytometry. The effect of Gleevec on p-Crkl, caspase-3, PARP and PDCD4 protein levels, and the knockdown efficacy of PDCD4 siRNA were detected by Western blotting. The results showed that Gleevec dramatically suppressed the phosphorylation level of Crkl in a dose-dependent manner and induced significant apoptosis and G0/G1 cell cycle arrest of K562 cells in time- and dose-dependent manners. In addition, Gleevec activated caspase-3 and its downstream substrates PARP, and the caspase pan inhibitor Z-VAD-FMK (50 micromol x L(-1)) markedly reduced Gleevec-induced apoptosis from 47.97% +/- 10.56% to 31.05% +/- 9.206% (P < 0.05). Moreover, Gleevec significantly increased the protein expression of programmed cell death 4 (PDCD4). PDCD4 knockdown by siRNA reduced Gleevec-induced apoptosis from 46.97% +/- 14.32% to 42.8% +/- 11.43%. In summary, Gleevec induced apoptosis in K562 cells via caspase-3 activation.

Exploration on new assessment methods for cell biology among postgraduates / 中华医学教育探索杂志

This paper summarized the assessment model reform practiced in the postgraduate cell biology course for several years and successfully obtain a new testing method based on research papers re-porting and questioning. Before the assessment, each student searched and selected one required research paper to read and make a PowerPoint reporting document. During assessment , some students were ex-tracted to speak and comprehensive score, which was regarded as student's final examination results was made by teaching group. The rest of the students listened to speeches , questioned and filled the questions on the record sheet.Teaching group reported a score , which was regarded as part of student's final exami-nation result based on questioning record sheets and printed PowerPoint documents.This method can well evaluate students' scientific thinking and strengthen the training of scientific thinking of postgraduates.

Chk1 gene scijencing potentiates human hepatoma Huh7 cells to curcumin-induced apoptosis / 中国癌症杂志

Background and purpose: Checkpoint kinase 1 and 2 have been proposed to be potential therapeutic targets to sensitize cancers to radio- or chemo-therapeutics. However, little is known about whether Chk1/2 is also a suitable target for sensitizing cancers to curcumin. In the present study, we investigated effects of Chk1/2 siRNA on curcumin-induced apopotosis in hepatoma cell line Huh7 and evaluated the effectiveness of Chkl/2as a therapeutic target to potentiate human hepatoma to curcumin. Methods: Effect of curcumin on the cell cycle checkpoint-associated proteins was detected by Westem blot. The knockdown efficacy of Chk1/2 siRNA was measured by RT-PCR and Westem blot. Effect of Chk1/2 siRNA on curcumin-induced apoptosis in Huh7 cells was evaluated by DAPI staining. Effect of Chk1/2 siRNA on cell cycle distribution in curcumin-treated Huh7 cells was analyzed by flow cytometry. Results: Curcumin significantly inhibited phosphorylation of cell cycle checkpoint-associtaed proteins Chk1(S317), Cdc25C(S216) and Cdk1(Y15). Chk1 siRNA decreased Chk1 mRNA and protein by 95% and 92% and Chk2 siRNA decreased Chk2 mRNA and protein by 60% and 55% respectively as compared with negative control siRNA (P<0.01). Inhibition of Chk1, but not Chk2, increased apoptotic rate from (21.3±1.8)% to (29.5±2.6)% (P<0.05). Neither Chk1 nor Cbk2 siRNA had any impact on cell cycle distribution in Huh7 cells induced by curcumin. Conclusion: Chk1 siRNA sensitized Huh7 cells to curcumin-induced apoptosis, suggesting that Chk1 is a potential therapeutic target to sensitize human hepatoma to curcumin.

Anticancer activities of curcumin on human hepatocarcinoma cell line Sk-hep-1 / 中国中药杂志

To study the anticancer activities of curcumin on human hepatocarcinoma cell line Sk-hep-1 and its related molecular mechanism which has not been elucidated. In the present study,we showed that curcumin inhibited proliferation of Sk-hep-1 cells in a dose-dependent manner through MTF assay. The effect of curcumin on apoptosis in Sk-hep-1 cells was investigated by DAPI staining and the various apoptosis was observed in hepatocarcinoma cell lines Sk-hep-1, HepG2 and Hep3B, but not in normal liver cell line Chang's liver with curcumin treatment. Cell cycle analysis results showed that curcumin treatment resulted in dramatic accumulation of Sk-hep-1 cells at the G0/G1 or G2/M phase. The effect of curcumin on the expression of anti-apoptosis genes (Survivin and BCl-xL) and drug resistance genes (DRG2 and MDR1) was studied by reverse transcription-polymerase chain reaction (RT-PCR). The expression of MDR1 mRNA was significantly decreased in Sk-hep-1 cells treated with curcumin, while no alterations in the amount of DRG2 and anti-apoptosis genes' mRNA levels were found. These results indicate that curcumin is able to inhibit proliferation and induce apoptosis in Sk-hep-1 cells and it may cause by down-regulating the expression of MDR1 mRNA.

Chk1 gene scilencing potentiates human hepatoma Huh7 cells to curcumin-induced apoptosis / 中国癌症杂志

Background and purpose:Checkpoint kinase 1 and 2 have been proposed to be potential therapeutic targets to sensitize cancers to radioor chemo-therapeutics. However, little is known about whether Chk1/2 is also a suitable target for sensitizing cancers to curcumin. In the present study, we investigated effects of Chk1/2 siRNA on curcumin-induced apopotosis in hepatoma cell line Huh7 and evaluated the effectiveness of Chk1/2 as a therapeutic target to potentiate human hepatoma to curcumin. Methods:Effect of curcumin on the cell cycle checkpoint-associated proteins was detected by Western blot. The knockdown efficacy of Chk1/2 siRNA was measured by RT-PCR and Western blot. Effect of Chk1/2 siRNA on curcumin-induced apoptosis in Huh7 cells was evaluated by DAPI staining. Effect of Chk1/2 siRNA on cell cycle distribution in curcumin-treated Huh7 cells was analyzed by flow cytometry. Results:Curcumin significantly inhibited phosphorylation of cell cycle checkpoint-associtaed proteins Chk1(S317), Cdc25C(S216) and Cdk1(Y15). Chk1 siRNA decreased Chk1 mRNA and protein by 95% and 92% and Chk2 siRNA decreased Chk2 mRNA and protein by 60% and 55% respectively as compared with negative control siRNA (P