In vivo effect of triptolide combined with glycyrrhetinic acid on rat cytochrome P450 enzymes / 药学学报

Triptolide (TP) is a major active component in Tripterygium root, but its therapeutic window was very narrow due to its severe multi-organ toxicity. In this work, the effect of TP combined with glycyrrhetic acid (GA) on mRNA expression and activity of four cytochrome P450 (CYP) enzymes in rat liver was studied after intragastric administration of TP (0.05, 0.3 and 0.6 mg x kg(-1) x day(-1)) and TP (0.6 mg x kg(-1) x day(-1)) combined with GA (30 mg x kg(-1) x day(-1)) for 7 consecutive days. Compared with the control, the high dose of TP significantly up-regulated the mRNA expression levels of CYP2E1, 1A2, 3A1 and 2C11, the co-administration of TP and GA further up-regulated the mRNA expression levels of CYP3A1, 2C11 and 2E1 as compared with the high dose of TP. Meanwhile, TP at high dose and combined with GA significantly increased CYP3A-associated testosterone 6beta-hydroxylation activity (2.2-fold and 4.1-fold, respectively) as compared with the control. Because TP is mainly metabolized by CYP3A2 in male rats, the present work indicated that TP-induced increase of CYP3A activity might be an important reason for the rapidly metabolic clearance of TP in rat liver, and GA can reduce the hepatotoxicity of TP by promoting its hepatic metabolic clearance. Furthermore, the results also suggest that the drug interactions might be occurred when TP and GA were co-administered with other CYP3A substrate drug.

In vitro metabolism of glycyrrhetic acid by human cytochrome P450 / 药学学报

Licorice root has been frequently used as antitode in traditional Chinese medicine. As the main active component of Licorice root, glycyrrhetic acid (GA) is mainly metabolized in liver. This study was designed to investigate the in vitro metabolism of GA by human liver microsomes (HLM) and human recombinant cytochrome P450 (CYP) isoforms. The results indicated that GA was metabolized mainly by CYP3A4. The K(m), V(max) and CL(int) of GA in HLM were 18.6 micromol x L(-1), 4.4 nmol x mg(-1) (protein) x min(-1) and 0.237 mL x mg(-1) (protein) x min(-1), respectively. At concentration up to 50 micromol x L(-1), GA inhibited CYP2C19, CYP2C9 and CYP3A4 enzyme activities with the inhibitory potencies up to 50%.

Connexin 43 expression in intraperitoneal free gastric cancer cells in patients with gastric cancer / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To examine the association of connexin 43 (Cx43) in the intraperitoneal free gastric cancer cells and clinicopathological characteristics.</p><p><b>METHODS</b>Immunohistochemistry and immunofluorescence staining were used to detect connexin 43 in 75 paraffin-embedded gastric cancer tissues, matched paracancerous tissue, and intraperitoneal free gastric cancer cells.</p><p><b>RESULTS</b>The positive rates of Cx43 expression were 33.3% (25/75) in gastric cancer tissue specimens and 100% (75/75) in matched paracancerous tissue (P<0.01). The positive detection rate of free cancer cells in peritoneal lavage was 38.6% (29/75) and the positive rate of Cx43 in peritoneal free gastric cancer cells was 72.4% (21/29), which was significantly higher than that in gastric cancer tissue specimens (P<0.01). Significant association was observed of Cx43 expression of free gastric cancer cells with tumor infiltration and histological type (P<0.05).</p><p><b>CONCLUSION</b>Cx43 gene may be involved in the mechanism of peritoneal metastasis of gastric cancer.</p>

Transcription regulation of 5-Aza-2'-deoxycytidine on maspin gene demethylation in RKO human colorectal cell line / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To detect the methylation status of 5'CpG island in the core promotor of maspin gene in RKO human colorectal cell line,and to explore the transcription regulation of DNA 5'CpG island demethylation on maspin tumor suppressor gene and its effect on the growth of cancer cell.</p><p><b>METHODS</b>The status of 5 'CpG island methylation of maspin gene in RKO human colorectal cell line was analyzed using methylation specific polymerase chain reaction (MSP). After treated with a specific demethylating agent, 5-Aza-2'-deoxycytidine, reverse transcription polymerase chain reaction (RT- PCR) was used to examine maspin gene expression. Cell proliferation was evaluated using MTT assay,distribution of cell cycle and rate of apoptosis were determined using flow cytometry.</p><p><b>RESULTS</b>The 5'CpG island methylation in the core promotor of maspin gene was detected in RKO human colorectal cell line. After treatment with three different concentration of 5-aza-2'-deoxycytidine, the expression of maspin mRNA increased 10.89, 16.91, 23.97 times respectively. MTT array showed the proliferation activity of RKO cell line was obviously reduced after 5-aza-2'-deoxycytidine treatment. The cells were arrested in G(0)/G(1) phase,and the apoptosis rates were 5.17%, 8.71% and 11.23% respectively compared with control group.</p><p><b>CONCLUSION</b>The 5'CpG island methylation is probably responsible for maspin expression silencing in RKO human colorectal cell line, 5-aza-2'-deoxycytidine may effectively cause demethylation and inhibit the growth of tumor cell by reactivating the gene transcription silenced by aberrant hypermethylation.</p>

The synergistic inhibitory effect of 5-aza-2-deoxycytidine and Tamoxifen on estrogen receptor alpha negative breast cancer cell lines in vitro / 中华外科杂志

<p><b>OBJECTIVE</b>To observe if ER alpha gene can be induced by 5-aza-CdR in ER alpha negative human breast cancer cell lines (MDA-MB-231 and MDA-MB-435) and the synergistic inhibitory effects of 5-aza-CdR and Tamoxifen on these two cell lines in vitro.</p><p><b>METHODS</b>The status of 5'CpG island methylation of ER alpha gene in ER alpha negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines and 20 cases of breast cancer tissue was studied by MSP, the expression of ER alpha mRNA was inspected by using RT-PCR after these two cell lines were treated with 5-aza-CdR. Cell proliferation was evaluated by MTT assay, distribution of cell cycle and rate of apoptosis were determined by flow cytometry after these two cell lines were treated with 5-aza-CdR or TAM alone, or in combination in vitro.</p><p><b>RESULTS</b>The 5'CpG island is methylated in the core promotor of ER alpha gene in ER alpha negative (MDA-MB-231 and MDA-MB-435) human breast cancer cell lines and the methylating rate is 25.0%, 66.7%, 83.3%, 100% in 20 cases of breast cancer tissue of stage I, II, III, IV, respectively. The expression of ER alpha mRNA was induced in these two cell lines after treated with 5-aza-CdR, MTT array showed the proliferation activity of these two cell lines was obviously reduced in 5-aza-CdR group and the inhibitory effect on proliferation was enhanced when 5-aza-CdR combined with TAM compared with control group, the induction of apoptosis was 11.20% and 8.71% respectively by 5-aza-CdR, while the rate of apoptosis is 48.8% and 53.1% when these two cells were treated with 5-aza-CdR combined with TAM.</p><p><b>CONCLUSIONS</b>5-aza-CdR can re-express ER alpha by demethylating and sensitive ER alpha negative human breast cancer cell lines to TAM, 5-aza-CdR and TAM synergistically inhibit proliferation and induce apoptosis in ER alpha negative human breast cancer cell lines, thus offer a new way for the treatment of ER alpha negative breast cancer.</p>