Effect of Bmi-1 Expression on Chemotherapy Sensitivity in THP-1 Cells / 中国实验血液学杂志

OBJECTIVE@#To investigate the effect of Bmi-1 expression on the chemosensitivity of THP-1 cells and its relative mechanism.@*METHODS@#The pGenesil-2-Bmi-1 1 siRNA, p-MSCV-Bmi-1 plasmid was transfected into THP-1 cells to reduce or increase the expression of Bmi-1. The expression of Bmi-1 mRNA and protein was verified by PCR and Western blot. The effect of camptothecin (CPT) on the proliferation and chemosensitivity of THP-1 cells affected by Bmi-1 gene were detected by MTT assay. The expression of DNA double-strand breaks marker-γ-H2AX was detected by immunofluorescence assay. Mitochondrial membrane potential and apoptosis were observed by flow cytometry. The expression of Cytochrome C, Caspase 3, Bax and BCL-2 was detected by Western blot.@*RESULTS@#Silencing Bmi-1 could inhibit proliferation and enhance the sensitivity of THP-1 cells to CPT, while overexpressed Bmi-1 could promote the cell proliferation and attenucate sensitivity of THP-1 cells to CPT. Silencing Bmi-1 could enhance CPT-induced DNA double-strand breaks, decrease mitochondrial membrane potential and promote CPT-induced apoptosis. While increasing Bmi-1 gene expression could attenuate CPT-induced DNA double-strand breaks, enhamce mitochondrial membrane potential and significantly reduce CPT-induced apoptosis of cells.@*CONCLUSION@#Bmi-1 expression could influence the sensitivity of THP-1 cells to CPT, and its relative mechanism may relate to DNA double-strand breaks and endogenous apoptotic pathways.

Nuclear factor E2-related factor 2 Dependent Overexpression of Sulfiredoxin and Peroxiredoxin III in Human Lung Cancer

BACKGROUND/AIMS: Oxidative stress results in protein oxidation and is implicated in carcinogenesis. Sulfiredoxin (Srx) is responsible for the enzymatic reversal of inactivated peroxiredoxin (Prx). Nuclear factor E2-related factor 2 (Nrf2) binds to antioxidant responsive elements and upregulates the expression of Srx and Prx during oxidative stress. We aimed to elucidate the biological functions and potential roles of Srx in lung cancer. METHODS: To study the roles of Srx and Prx III in lung cancer, we compared the protein levels of Nrf2, Prxs, thioredoxin, and Srx in 40 surgically resected human lung cancer tissues using immunoblot and immunohistochemical analyses. Transforming growth factor-beta1, tumor necrosis factor-alpha, and camptothecin treatment were used to examine Prx III inactivation in Mv1Lu mink lung epithelial cells and A549 lung cancer cells. RESULTS: Prx I and Prx III proteins were markedly overexpressed in lung cancer tissues. A significant increase in the oxidized form of a cysteine sulfhydryl at the catalytic site of Prxs was found in carcinogenic lung tissue compared to normal lung tissue. Densitometric analyses of immunoblot data revealed significant Srx expression, which was higher in squamous cell carcinoma tissue (60%, 12/20) than in adenocarcinoma (20%, 4/20). Also, Nrf2 was present in the nuclear compartment of cancer cells. CONCLUSIONS: Srx and Prx III proteins were markedly overexpressed in human squamous cell carcinoma, suggesting that these proteins may play a protective role against oxidative injury and compensate for the high rate of mitochondrial metabolism in lung cancer.

Effects of mitofusin-2 gene on cell proliferation and chemotherapy sensitivity of MCF-7 / 华中科技大学学报（医学）（英德文版）

In order to evaluate the effect of mitofusin-2 gene (mfn2) on proliferation and chemotherapy sensitivity of human breast carcinoma cell line MCF-7 in vitro, pEGFPmfn2 plasmid carrying full length of mitofusin-2 gene was transfected, by using sofast, into MCF-7 cells. Mitofusin-2 gene expression in MCF-7 cells transfected by sofast after 48 h was detected by PCR and Western blotting, and the stable expression of GFP protein in MCF-7 cells by Western blot analysis. The proliferation of MCF-7 cells was assayed by MTT and cell counting. By using PI method, the effects of mfn2 on the cell cycle distribution of MCF-7 were measured. Annexin-V/PI double labeling method was employed to detect the changes in apoptosis induced by chemotherapeutics before and after transfection. The results showed that the MCF-7 cells transfected with mfn2 gene could stably and highly express GFP protein. MTT assay revealed that after transfection of mfn2 cDNA, the proliferation of MCF-7 cells was significantly inhibited. DNA histogram showed that cells arrested in S phase, and the percentage of S phase cells was 42.7, 17.2 and 19.6 in mfn2 cDNA transfection group, blank plasmid transfection group and blank control group, respectively (P<0.05). The apoptosis ratio of the cells transfected with mfn2 gene was increased from 3.56% to 15.95%, that of the cells treated with camptothecin (CAMP) followed by mfn2 gene transfection was 69.6%, and that in blank plasmid transfection group and blank control group was 31.0% and 23.4% respectively (P<0.05). It was suggested that transfection of mfn2 gene could significantly inhibit the proliferation of MCF-7 cells and promote their sensitivity to CAMP with a synergic effect.

O emprego de sistemas de liberação como estratégia para melhorar as propriedades terapêuticas de fármacos de origem natural: o exemplo da camptotecina e seus derivados / Drug delivery systems as a way to improve the therapeutic properties of natural drugs: the example of camptothecin and its derivatives

As plantas têm sido utilizadas para a obtenção de um grande número de substâncias biologicamente ativas. Entretanto, muitos compostos naturais quando empregados sem qualquer modificação química não resultaram em medicamentos eficazes, por não apresentarem as características desejáveis para administração. Neste sentido, a melhoria das propriedades terapêuticas de compostos isolados de plantas por meio da sua incorporação em sistemas de liberação de fármacos consiste em uma importante estratégia na obtenção de novos medicamentos, na qual ainda existe muito a ser explorado. Tais sistemas são caracterizados por apresentar a capacidade de prolongar e controlar a liberação de substâncias ativas, proteger as moléculas frente à degradação no meio biológico, veicular fármacos hidrofóbicos e reduzir os efeitos colaterais indesejáveis. A camptotecina, um alcalóide proveniente do arbusto Camptotheca acuminata (Descaisne, Nyssaceae), é um fármaco que apresenta elevada atividade antitumoral, cujo mecanismo envolve a inibição da topoisomerase I, uma enzima altamente expressa nos tumores. Entretanto, a utilização deste fármaco na terapêutica foi limitada, durante anos, em virtude de suas características de baixa solubilidade aquosa, elevada instabilidade em meio fisiológico e elevada toxicidade. Neste artigo é realizada uma revisão sobre o potencial terapêutico da camptotecinae seus análogos no tratamento do câncer, dando ênfase aos estudos conduzidos com o intuito de contornar as limitações da administração destes fármacos e que resultaram na melhoria das propriedades terapêuticas. Estratégias como a microencapsulação, nanoencapsulação e solubilização em micelas poliméricas, entre outras, são discutidas e os principais resultados de atividade antitumoral in vitro e in vivo são apresentados.

Weekly irinotecan in patients with progressive or rapidly recurrent colorectal cancer pretreated with fluorouracil-based chemotherapy

To prospectively evaluate efficacy and tolerability of weekly irinotecan [CPT-11] in patients with advanced colorectal carcinoma [CRC] that had recurred or progressed following fluorouracil [5-FU]-based therapy. Forty eight patients were enrolled in this study. They were treated with irrinotecan 125 mg/m[2] intravenously [IV] every week for 4 weeks, followed by a 2- week rest. All patients were accessible for toxicity and only 44 patients completed one full course of therapy and were accessable for response. Nine patients [20.5%] attained partial response [95% CI, 10% to 27%] and no cases achieved complete response. The median duration of response was 7 months [range4to 11.5 months]. The median survival time was 10 months [95% CI 8.2 to 13.1 months] and the 1-year survival rate was 43.8% [95% CI, 33% to 53%]. Median time to progression was 4.0 months [95% CI, 2.6 to 5.1 months]. Grade 3-4 diarrhea was observed in 17 patients [35.4%], grade 3-4 nausea and vomiting in 3 patients [6.3%] and 4 patients [8.3%] respectively. Grade 3-4 neutropenia was reported in 5 patients [31.3%]. Grade 3-4 febrile neutropenia or infection affected only 2 patients [4.2%]. Weekly schedule of irinotecan has demon strated significant activity against colorectal cancer that has progressed during or shortly after treatment with 5-FU-based chemotherapy. Diarrhea is the most frequent dose limiting toxicity but can be substantially reduced through appropriate interventional management

Irinotecan and oxaliplatin: an overview of the novel chemotherapeutic options for the treatment of advanced colorectal cancer

Colorectal cancer is one of the most frequent malignancies in humans and an important cause of cancer death. Metastatic colorectal cancer remains incurable with available systemic therapeutic options. The most active cytotoxic drug against this malignancy, the antimetabolite 5-fluorouracil, was developed more than forty years ago, and as a single agent produces responses in only 10 to 15 percent of patients which in general last less than one year. Efforts to ameliorate these poor results resulted in the 5-fluorouracil/leucovorin combination, which enhances response rates about two-fold, without, however, significantly improving survival rates. The recent emergence of a handful of new 5-fluorouracil analogues and folate antagonists, as well as the topoisomerase I inhibitor irinotecan, and the third-generation platinum compound oxaliplatin, is likely to alter this gloomy scenario. These agents are at least as effective as 5-fluorouracil in patients with advanced colorectal carcinoma, both untreated and previously treated with 5-fluorouracil-based regimens. This has led to the approval of irinotecan as second-line treatment for 5-fluorouracil-refractory disease, while the use of oxaliplatin has been suggested for patients having a defective 5-fluorouracil catabolism. Recently, FDA approved the combination of irinotecan with 5-fluorouracil and leucovorin for first-line treatment of advanced colon cancer. Based on the synergistic preclinical antitumor effects of some of these agents, their meaningful single-agent activity, distinct mechanisms of cytotoxicity and resistance, and only partially overlapping toxicity profiles, effective combination regimens are now being developed, which are likely to lead to a new, more hopeful era for patients suffering from advanced colorectal carcinoma

Partial purification and characterization of DNA topoisomerase II from Plasmodium falciparum.

DNA topoisomerase II from Plasmodium falciparum was partially purified by FPLC using three columns: Econo-Pac Q, heparin-agarose and Mono Q. The enzyme showed ATP- and Mg2 +/- dependent activities in a decatenation assay, with optimum concentrations of 0.5 and 10 mM, respectively. Furthermore, highest activity was detected in the presence of 100 mM KCI. Enzyme decatenation activity was not inhibited by the DNA topoisomerase I inhibitor, camptothecin, but was sensitive to both prokaryotic and eukaryotic DNA topoisomerase II inhibitors.