Reversal of resistance to adriamycin in human breast cancer cell line MCF-7/ADM by silencing AEG-1 gene and its mechanism / 生理学报

The aim of this study was to investigate the effects of AEG-1 gene silencing on the chemoresistance of human breast cancer cell line MCF-7/ADM and its possible mechanism. MCF-7/ADM cells were incubated in the medium containing adriamycin (ADM). The recombinant pLKO.1-shAEG-1 plasmid was constructed to silence AEG-1 expression in human breast cancer MCF-7/ADM cells. MTT assay was employed to detect the anti-tumor effect of ADM on MCF-7/ADM cells, and IC50 value of ADM was calculated according to MTT. Flow cytometry was used to determine the apoptosis. Western blot was used to analyze the expression levels of AEG-1, p-Akt, p-MDM2, p-Bad, p53 and MDR1. The result showed MCF-7/ADM had a significantly higher expression level of AEG-1 compared with that of MCF-7 (P < 0.05), however, the expression of AEG-1 was decreased after AEG-1 gene silencing. The IC50 value of ADM in shAEG-1 group was significantly lower than that in shcontrol group. AEG-1 gene silencing induced cell apoptosis and enhanced the pro-apoptotic effect of ADM on MCF-7/ADM cells. After AEG-1 gene silencing, the phosphorylation of Akt, MDM2 and Bad was inhibited (P < 0.05), the protein levels of p53 and MDR1 were up-regulated (P < 0.05) and down-regulated (P < 0.05) respectively, compared with control. In conclusion, the results suggest that AEG-1 gene silencing can reverse the ADM resistance in human breast cancer cell line MCF-7/ADM by means of inducing apoptosis and down-regulating the protein level of MDR1.

Inhibitory effect of exogenous insulin-like growth factor binding protein 7 on proliferation of human breast cancer cell line MDA-MB-453 and its mechanism / 生理学报

The present study was to investigate the effects of exogenous insulin-like growth factor binding protein 7 (IGFBP7) on the proliferation of human breast cancer cell line MDA-MB-453 and its possible mechanism. By means of MTT method in vitro, the results showed exogenous IGFBP7 inhibited the growth of MDA-MB-453 cells (IC50 of IGFBP7 = 8.49 μg/mL) in time- and concentration-dependent manner. SB203580, p38(MAPK) inhibitor, blocked the anti-proliferative effect of exogenous IGFBP7. The flow cytometry assay showed that exogenous IGFBP7 remarkably induced G0/G1 arrest in MDA-MB-453 cells. The Western blot showed that exogenous IGFBP7 promoted phosphorylation of p38(MAPK), up-regulated expression of p21(CIP1/WAF1), and inhibited phosphorylation of Rb. SB203580 restrained exogenous IGFBP7-induced regulation of p21(CIP1/WAF1) and p-Rb in MDA-MB-453 cells. In conclusion, the present study suggests that exogenous IGFBP7 could activate the p38(MAPK) signaling pathway, upregulate p21(CIP1/WAF1) expression, inhibit phosphorylation of Rb, and finally induce G0/G1 arrest in MDA-MB-453 cells.

Screening drugs for regulating tissue factor gene expression / 中国实验血液学杂志

This study was purposed to screen the drugs for regulating tissue factor (TF) gene expression through establishing stable cell line with luciferase gene having TF promoter transcription activity, so as to provide the basis for further studying the molecular mechanism of screened drugs. A series of luciferase reporter gene plasmids under control of 5'-truncated TF promoter (including -2174 bp - +128 bp, -684 bp - +128 bp, -247 bp - +128 bp and -201 bp - +128 bp) were constructed. The above plasmids were separately electroporated into U937 cells to establish stably transfected sublines. The function of stable cell line was testified by treatment with ATRA, the luciferase gene activity was analyzed by treating established cell line with bortezomib (BTZ) and CDA-II, and drugs for regulating TF gene expression were screened. The results indicated that the BTZ of 5 nmol/L could activate TF gene transcription activity, up-regulate the expression level of TF transcripts; CDA-II of 1 mg/ml could suppress TF gene transcription activity, down-regulate the expression level of TF transcripts. The functional analysis of TF promoter transcription revealed that the region of regulating TF promoter transcription activity by BTZ and CDA-II was between -201 to 0 bp. It is concluded that stable cell line U937 expressing luciferase activity of TF promoters is established, the novel drugs regulating TF gene expression are screened out by means of this established cell line. This study provides basis for screening the new drugs and further studying their molecular mechanisms.

Establishment of stable subline of K562 cells overexpressing high mobility group B1 protein / 中国实验血液学杂志

This study was aimed to establish a stable subline of K562 cells (K562-HMGB1) overexpressing HMGB1 protein and K562-HMGB1 sublines served as control, so as to provide a basis for exploring the role of hmgb1 gene in occurrence and development of leukemia and their mechanism. Protein-coding gene of hmgb1 was amplified by PCR with cDNA as template, which was synthesized by reverse transcription from total RNA extracted from U937 cells. The PCR-amplified hmgb1 gene was ligated into PMD18-T vector (PMD18-T-HMGB1 vector), and then transformed into E. coli strain DH5α. DH5α containing PMD18-T-HMGB1 vector were grown on LB agar plate supplemented with 100 µg/ml ampicillin overnight. The single ampicillin-selected DH5α clone was picked for culturing overnight and then harvested for plasmid extraction. The extracted plasmid was characterized to contain hmgb1 gene digested with the desired restriction enzymes of KpnI/XhoI. The correctness of hmgb1 sequence was confirmed with DNA sequencing. The insert of hmgb1 gene contained in PMD18-T-HMGB1 vector was cut out with restriction enzymes of KpnI/XhoI and then ligated into eukaryotic expression vector pcDNA3.1 to form pcDNA3.1-HMGB1 vector. 10µg of pcDNA3.1-HMGB1 or pcDNA3.1 plasmid was separately electroporated into K562 cells. At 48 hours after electroporation the cells were cultured with G418 at a final concentration of 800 µg/ml for over 2 weeks. Finally stably transfected sublines of K562 cells containing hmgb1 gene (K562-HMGB1), and of K562 containing pcDNA3.1 vector (K562-pcDNA3.1) served as a control, were obtained. The transcriptional or translational expression of hmgb1 gene was detected with RT-PCR or Western blot, respectively, to testify transfected efficiency and validity of stable subline of K562-HMGB1. The results indicated that the eukaryotic expression vector pcDNA3.1-HMGB1 plasmid was successfully constructed and was electroporated into K562 cells. The transcriptional or translational expression of hmgb1 gene in the stable subline of K562 cells containing hmgb1 gene was overexpressed. It indicated that stable subline of K562-HMGB1 cells was successfully established. It is concluded that the stable sublines of K562-HMGB1 cells or K562-pcDNA3.1 cells are successfully established, which provides a basis for exploring the roles and mechanisms of hmgb1 gene in leukemogenesis and development of leukemia.