Biomedical subjects

Rui Han

Publications and source records attributed to Rui Han.

24 records · Page 2Linked to original sources

PubMed2003

Taxol inhibits melanoma metastases through apoptosis induction, angiogenesis inhibition, and restoration of E-cadherin and nm23 expression.

An in vivo melanoma spontaneous metastases model was adopted to study the molecular mechanisms of the anti-metastatic effect of Taxol. The morphology of melanoma cells in the melanoma tissue lesions was examined by hematoxylin/eosin (H&E) staining and electron microscopy. The in situ programmed cell death was tested by TUNEL analysis. Vascular endothelial growth factor (VEGF) and E-cadherin expression were detected by immunohistochemistry. The metastases suppressor gene nm23 mRNA expression level was analyzed by in situ hybridization. The results showed that i.p. injection of Taxol at 5 mg/kg per day for three weeks significantly inhibited metastases formation in the pulmonary of mice. Taxol induced melanogenesis and apoptosis in the melanoma cells, inhibited angiogenesis in melanoma tissue lesions, and reduced the expression of VEGF. Conversely, Taxol increased the expression of E-cadherin and nm23. In conclusion, administration of Taxol in the early stage of melanoma metastases can significantly inhibit melanoma metastases. This effect was possibly related to apoptosis induction, tumor angiogenesis inhibition, and restoration of the metastasis suppression ability.

Angiogenesis Inhibitors↗

PubMed2003

[Experimental studies on the apoptosis of HL-60 cells induced by Brucea javanica oil emulsion].

OBJECTIVE: To investigate the inducing effect of Brucea javanica on the apoptpsis of HL-60 cells. METHOD: HL-60 cells were treated with Brucea javanica 1:100, 1:40, 1:20 (v/v) respectively for 6 h and DNA agarose gel electrophoresis, flow cytometry, fluorescence microscope, electron microscope were used to observe the apoptosis inducing effect of Brucea javanica. RESULT: DNA ladder was seen in the 1:40 group. The apoptosis cell percentages of 1:40 and 1:20 group were 86.8% and 97% respectively. Cells of 1:40 group showed obvious apoptosis character under fluorescence microscope. Cells were induced apoptosis in 1:20 and 1:40 Brucea javanica under electron microscope. CONCLUSION: 1:20 and 1:40 Brucea Javanica showed obvious apoptosis inducing effect of HL-60.

Antineoplastic Agents, Phytogenic↗

PubMed2002

Cytoplasmic prostaglandin E2 synthase is dominantly expressed in cultured KAT-50 thyrocytes, cells that express constitutive prostaglandin-endoperoxide H synthase-2. Basis for low protaglandin E2 production.

The recent identification and cloning of two glutathione-dependent prostaglandin E(2) synthase (PGES) genes has yielded important insights into the terminal step of PGE(2) synthesis. These enzymes form efficient functional pairs with specific members of the prostaglandin-endoperoxide H synthase (PGHS) family. Microsomal PGES (mPGES) is inducible and works more efficiently with PGHS-2, the inflammatory cyclooxygenase, while the cytoplasmic isoform (cPGES) pairs functionally with PGHS-1, the cyclooxygenase that ordinarily exhibits constitutive expression. KAT-50, a well differentiated thyroid epithelial cell line, expresses high levels of PGHS-2 but surprisingly low levels of PGE(2) when compared with human orbital fibroblasts. Moreover, PGHS-1 protein cannot be detected in KAT-50. We report here that KAT-50 cells express high basal levels of cPGES but mPGES mRNA and protein are undetectable. Thus, KAT-50 cells express the inefficient PGHS-2/cPGES pair, and this results in modest PGE(2) production. The high levels of cPGES and the absence of mPGES expression result from dramatic differences in the activities of their respective gene promoters. When mPGES is expressed in KAT-50 by transiently transfecting the cells, PGE(2) production is up-regulated substantially. These observations indicate that naturally occurring cells can express a suboptimal profile of PGHS and PGES isoforms, resulting in diminished levels of PGE(2) generation.

Blotting, Northern↗

PubMed2002

Up-regulation of prostaglandin E2 synthesis by interleukin-1beta in human orbital fibroblasts involves coordinate induction of prostaglandin-endoperoxide H synthase-2 and glutathione-dependent prostaglandin E2 synthase expression.

Prostaglandin E(2) (PGE(2)) production involves the activity of a multistep biosynthetic pathway. The terminal components of this cascade, two PGE(2) synthases (PGES), have very recently been identified as glutathione-dependent proteins. cPGES is cytoplasmic, apparently identical to the hsp90 chaperone, p23, and associates functionally with prostaglandin-endoperoxide H synthase-1 (PGHS-1), the constitutive cyclooxygenase. A second synthase, designated mPGES, is microsomal and can be regulated. Here we demonstrate that mPGES and PGHS-2 are expressed at very low levels in untreated human orbital fibroblasts. Interleukin (IL)-1beta treatment elicits high levels of PGHS-2 and mPGES expression. The induction of both enzymes occurs at the pretranslational level, is the consequence of enhanced gene promoter activities, and can be blocked by dexamethasone (10 nm). SC58125, a PGHS-2-selective inhibitor, could attenuate the induction of mPGES, suggesting a dependence of this enzyme on PGHS-2 activity. IL-1beta treatment activates p38 and ERK mitogen-activated protein kinases. Induction of both mPGES and PGHS-2 was susceptible to either chemical inhibition or molecular interruption of these pathways with dominant negative constructs. These results indicate that the induction of PGHS-2 and mPGES by IL-1beta underlies robust PGE(2) production in orbital fibroblasts.

Blotting, Northern↗

PubMed2002

[Anti-mutagenicity activity of dehydroepiandrosterone].

OBJECTIVE: The chemopreventive activity and mechanism of dehydroepiandrosterone (DHEA) were studied. METHODS: Model of 7, 12-dimethylbenz (alpha) anthracene (DMBA) induced breast carcinoma in Sprague-Dawley rats, uitra-violet (UV)-induced DNA damage and Salmonella mutation assay were used. RESULTS: In DMBA-induced rat mammary tumor model, the rats were orally given daily DHEA for 2 weeks before DMBA and continued for 10 weeks after DMBA administration. The results showed significant inhibition of tumor development by DHEA. The incidence of mammary carcinoma also decreased significantly on daily dose of oral 25 mg/kg DHEA with the mean tumor volume per rat also remarkably reduced by 92%. Moreover, 25 mg/kg DHEA treatment could significantly increase the carcinoma latency for about 3.5 weeks as compared with the control. Using polymerase chain reaction (PCR) assay, in vitro 10(-9) mol/L DHEA showed significant inhibitory effect on UV-induced DNA damage by 90%. In Ames test, DHEA was found to decrease DMBA and benzo (alpha) pyrene-induced TA98 and TA100 His(+) revertants markedly and the number of Salmonella clones were significantly reduced by 53.2% and 73.0% on dose of 5 microgram DHEA/plate. It was also shown that in vitro 10(-7) mol/L DHEA could also effectively inhibit the G-6-PDH activity, which might play an important role in its chemoprophylaxis activities. CONCLUSION: The results strongly prove that DHEA is a potent cancer chemoprophylaxis agent, which exhibits inhibitory potential on mutation and chemical carcinogen in vivo and in vitro.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2002

[Development of research for drug-resistance mechanism of taxol].

The resistant problem is the main restriction factor for clinical usage of taxol. The main mechanism of its resistance includes the high expression of P-gp, beta- and alpha-tubulin isotypes, the alteration expression of PKC, Bcl-2, p53, and ErbB2. The reversing method includes the use of analogues of taxol to reduce the expression of P-gp, or the use of antibody, immunotoxin, antisence oligonucleotide, and liposomes. The combination with other drugs can also be a method to reverse the resistance of taxol.

ATP Binding Cassette Transporter, Subfamily B, Mem↗