Endonuclease G promotes cell death of non-invasive human breast cancer cells

The invasiveness of breast cancer cells was shown to be associated with the suppressed ability to develop apoptosis. The role of cell death DNases/endonucleases has not been previously examined in relation with the invasiveness of breast cancer cells. We have compared the activity of the endonucleases in seven human breast cancer cell lines different in the level of invasiveness and differentiation. The invasiveness of cell lines was confirmed by an in vitro Matrigel-based assay. The total endonuclease activity in the differentiated non-invasive (WDNI) cell lines was higher than that in the poorly differentiated invasive (PDI) cells. The expression of EndoG strongly correlated with the degree of estrogen receptor expression and showed an inverse correlation with vimentin and matrix metalloproteinase-13. The EndoG-positive WDNI cells were more sensitive to etoposide- or camptothecin-induced cell death than EndoG-negative PDI cells. Silencing of EndoG caused inhibited of SK-BR-3 WDNI cell death induced by etoposide. Human ductal carcinomas in situ expressed high levels of EndoG, while invasive medullar and ductal carcinomas had significantly decreased expression of EndoG. This correlated with decreased apoptosis as measured by TUNEL assay. Our findings suggest that the presence of EndoG in non-invasive breast cancer cells determines their sensitivity to apoptosis, which may be taken into consideration for developing the chemotherapeutic strategy for cancer treatment.     

The molecular basis of multidrug resistance in cancer: the early years of P-glycoprotein research

The discovery and characterization of P-glycoprotein, an energy-dependent multidrug efflux pump, as a mechanism of multidrug resistance in cancer is generally accepted as a significant contribution to the ongoing effort to end death and suffering from this disease. The historical reflections of Victor Ling and Michael Gottesman concerning the early years of this research highlight the important contributions of the multidisciplinary teams involved in these studies, and illustrate how technological developments in biochemistry and molecular and cell biology enabled this discovery.     

Concomitant chemo-radiotherapy for unresectable oesophageal cancer: A mono-institutional study on 40 patients

Background/AimTo analyse clinical response, overall (OS) and disease free survival (DFS) and toxicity in patients with unresectable oesophageal cancer treated by concomitant chemo-radiotherapy (CRT).Materials and methodsForty patients with stage IIa–IVa biopsy proven oesophageal carcinoma were treated with CRT. All patients were studied with endoscopy and CT and judged unresectable after multidisciplinary discussion. CRT consisted of 3 cycles of cisplatin 100 mg/m² or carboplatin 300 mg/m² on day 1 and 5-fluorouracil 1000 mg/m² as a continuous infusion of 96 h associated with concurrent 3D-conformal RT. By using 15 MeV X-rays, a total dose of 60–66 Gy was delivered with daily fractions of 1.8–2.0 Gy.ResultsComplete response (CR), partial response (PR) and no response (NR) were observed in 50%, 20% and 20% of cases, respectively. Of the 20 patients with CR, 15 developed loco-regional recurrent disease. OS and DFS rates at 3 and 5 years were 38%, 8%, 49% and 10%, respectively. Total radiation dose ≥60 Gy improved loco-regional control and complete response (CR vs. PR + NR; p = 0.004) influenced both DFS and loco-regional control. Grade 3 gastrointestinal and haematological acute toxicity occurred in 3/40 patients (7.5%). One patient developed grade 4 renal failure. Late toxicity was reported in 2/40 patients (5.0%), consisting of grade 3 radiation pneumonitis.ConclusionsConcomitant CRT for unresectable oesophageal cancer can result in an acceptable loco-regional control with limited toxicity. Response after treatment and total radiation dose influenced the outcome.     

体外药物敏感实验为依据的恶性脑胶质瘤个体化化疗初步研究

目的:建立胶质瘤细胞体外原代培养模型,利用MTT法进行体外药物敏感实验,为临床化疗方案的设计提供理论指导,实施个体化化疗。方法:32例术后病理证实为胶质瘤(WHOⅢ级)的新鲜标本,制备肿瘤单细胞悬液进行体外原代培养,与7种抗肿瘤药物在临床血浆峰值浓度(PPC)条件下作用72小时,MTT法标记存活的肿瘤细胞,用酶标仪检测光密度值(OD),计算出抑制率(IR),检测不同肿瘤个体对化疗药物的敏感和耐药情况,从而指导临床个体化化疗方案的制定。另选取同期符合上述入选标准的20例间变型星形细胞瘤患者作为对照组,按照VM-26加DDP方案经验化疗,化疗4个疗程结束后,复查影像学,按照WHO肿瘤疗效评价标准评价治疗效果,分为稳定(SD),进展(PD),缓解(PR)。结果:32例临床标本的原代培养及药敏试验,其PPC下的抑制率(IR%)>50%者,DDP有20例;VCR有9例;VM-26有12例;VP-16有17例;Procarbazine有7例;BCNU有6例;Taxol有3例;其敏感性依次为:DDP>VP-16>VM-26>VCR>Procarbazine>BCNU>Taxol。根据体外药物敏感实验结果制定个体化化疗方案治疗29例,肿瘤缓解率为47.2%,对照组为29.4%,2组x2检验统计P<0.05。结论:7种常用的抗肿瘤药物均有耐药的情况,进行化疗药物的敏感测定可以避免耐药药物的使用。根据体外药物敏感实验结果制定个体化化疗方案化疗与对照组相比近期疗效较满意。     

DNA damage in peripheral blood lymphocytes in patients during combined chemotherapy for breast cancer

Combined chemotherapy is used for the treatment of a number of malignancies such as breast cancer. The target of these antineoplastic agents is nuclear DNA, although it is not restricted to malignant cells. The aim of the present study was to assess DNA damage in peripheral blood lymphocytes (PBLs) of breast cancer patients subjected to combined adjuvant chemotherapy (5-fluorouracil, epirubicin and cyclophosphamide, FEC), using a modified comet assay to detect DNA single-strand breaks (SSB) and double-strand breaks (DSB).

Forty-one female patients with advanced breast cancer before and after chemotherapy and 60 healthy females participated in the study. Alkaline and neutral comet assays were performed in PBLs according to a standard protocol, and DNA tail moment was measured by a computer-based image analysis system.

Breast cancer patients before treatment had higher increased background levels of SSB and DSB as compared to healthy women. During treatment, a significant increase in DNA damage was observed after the 2nd cycle, which persisted until the end of treatment. Eighty days after the end of treatment the percentage of PBLs with SSB and DSB remained elevated, but the magnitude of DNA damage (tail moment) returned to baseline levels. There was no correlation between PBL DNA damage and response to chemotherapy.

DNA-SSB and DSB in PBLs are present in cancer patients before treatment and increase significantly after combined chemotherapy. No correlation with response to adjuvant chemotherapy was found. Biomonitoring DNA damage in PBLs of cancer patients could help prevent secondary effects and the potential risks of developing secondary cancers.     

Trypanosoma cruzi: Induction of benznidazole resistance in vivo and its modulation by in vitro culturing and mice infection

Through a continuous in vivo drug pressure protocol, using mice as experimental model, we induced benznidazole resistance in Trypanosoma cruzi stocks. Full resistance was obtained for four out of five T. cruzi stocks analyzed. However, the number of benznidazole doses (40–180), as well as the time (4–18 months) necessary to induce resistance varied among the different T. cruzi stocks. The resistance phenotype remained stable after T. cruzi stocks has been maintained by 12 passages in mice (six months) and in acellular culture for the same time. However, the maintenance of resistant parasite for 12 months in acellular culture induces a reduction in its level of benznidazole resistance, while no alteration was detected in parasite maintained for the same time in mice. The data showed the stability of the resistance acquired by drug pressure, but suggest the possibility of reversible changes in the resistance levels after maintenance for long time in acellular culture.     

In vitro trypanocidal activity of the anti-helminthic drug niclosamide

Only a few drugs are available for chemotherapy of African trypanosomiasis and there is an urgent need for the development of new anti-trypanosomal agents. In this study, the anti-helminthic drug niclosamide was tested for its trypanocidal activity in vitro using culture-adapted bloodstream forms of Trypanosoma brucei brucei and Trypanosoma congolense. The concentrations of niclosamide to reduce the growth rate by 50% and to kill all cells were in the low- and mid micromolar ranges for T. b. brucei and T. congolense, respectively. The very low toxicity of niclosamide for mammals makes the compound interesting for drug development for African trypanosomiasis.     

Methyl angolensate, a natural tetranortriterpenoid induces intrinsic apoptotic pathway in leukemic cells

Methyl angolensate (MA), a natural tetranortriterpenoid, purified from Soymida febrifuga is examined for the first time for its anticancer properties. We find that MA inhibits growth of T-cell leukemia and chronic myelogenous leukemia cells in a time- and dose-dependent manner. Accumulation of cells in the subG1 peak, annexin V binding and DNA fragmentation suggested induction of apoptosis. Besides, upregulation of BAD (proapoptotic) and downregulation of BCL2 (antiapoptotic) gene products further supported induction of apoptosis. Loss of mitochondrial membrane potential, activation of caspase 9, caspase 3, cleavage of PARP, downregulation of Ku70/80 and phosphorylation of MAP kinases suggested that MA could induce intrinsic pathway of apoptosis in leukemic cells.