血红素加氧酶-1对TNF-α引起内皮细胞炎症损伤的保护作用

目的探讨血红素加氧酶-1(HO-1)在肿瘤坏死因子-α(TNF-α)导致肺微血管内皮细胞损伤中的保护作用。方法采用TNF-α刺激人肺微血管内皮细胞(HPMECs)模拟重症急性胰腺炎肺损伤的体外模型,锌原卟啉-IX(ZNPP-IX)作为HO-1抑制剂预处理细胞。试验分为对照组、TNF-α组、ZNPP-IX组。CCK8比色法检测细胞活性,采用Western blotting法及RT-PCR法检测HO-1、细胞间黏附分子-1(ICAM-1)的表达,黏附试验检测HPMECs对多形核细胞(PMN)的黏附力。结果 1与对照组相比,TNF-α组(78.69%±5.54%)、ZNPP-IX组(62.00%±4.27%)细胞活性明显降低(P0.01);2与对照组相比,TNF-α组(1.59±0.19)HO-1表达增高(P0.05),ZNPP-IX组(0.01±0.01)比TNF-α组显著降低(P0.01);3与对照组相比,TNF-α组(32.72±0.95)、ZNPP-IX组(85.33±2.37)ICAM-1表达明显升高(P0.01),且ZNPP-IX组比TNF-α组更显著(P0.01);4TNF-α引起HPMECs对PMN黏附力增高,抑制HO-1表达后,黏附作用增强。结论 HO-1可能通过下调ICAM-1的表达降低炎症时HPMECs对PMN的黏附,从而改善重症急性胰腺炎引起的肺损伤。     

Human gastric mucosal adenylate cyclase activity: effects of various cytoprotective prostaglandins

Several prostaglandins prevent ulcer formation (called cytoprotection) by a mechanism other than inhibition of gastric acid secretion. One suggestion is that they increase cyclic AMP in non-parietal cells. A variety of prostaglandins with potent cytoprotective properties were tested for their capacity to modulate adenylate cyclase activity in homogenates of human gastric mucosa. Prostaglandin E2, prostacyclin (PGI2) and 15(S)-methyl-PGE2 stimulated the cyclase in human gastric mucosal biopsy specimens in a dose-dependent manner. Cytoprotective prostaglandins without antisecretory properties such as PGF2 beta were also able to activate the enzyme system dose-dependently. In contrast, cytoprotective prostaglandins such as PGD2, the PGE1-analogue, SC-29333, and the prostaglandin-like compound C83 did not stimulate human gastric adenylate cyclase. Whereas PGD2 did not modulate enzyme activity at all, SC-29333 and C83, at concentrations greater than 10 mumol/l, inhibited basal and PGE2-stimulated enzyme activities. These studies suggest that cyclic AMP is not directly related to the cytoprotective effect of prostaglandins, at least in human gastric mucosa.     

Catecholamine concentrations in biopsied gastroduodenal tissue specimens of patients with duodenal ulcer

We measured dopamine and norepinephrine concentrations in the biopsied gastroduodenal mucosa obtained from 12 ulcer-free dyspeptic patients, nine patients with active duodenal ulcer, and eight patients with inactive (or healed) duodenal ulcer using a high-performance liquid chromatography with electrochemical detection method. Biopsy specimens were taken from endoscopically normal-appearing mucosa in the gastric body and antrum as well as in the duodenal bulb. Additional specimens were obtained from the outer edge of the ulcer margin in patients with active duodenal ulcer. The mean (±SD) mucosal dopamine concentrations in the gastric body and duodenum (7.6±2.8 and 6.8±2.6 pg/mg tissue) obtained from patients with inactive duodenal ulcer were significantly (P<0.05) lower than those from dyspeptic patients (13.6±6.9 and 10.9±3.5 pg/mg tissue, respectively). In contrast, no significant differences were observed in the mean norepinephrine concentrations in these gastroduodenal tissues among the three study groups. However, the mean mucosal norepinephrine concentration in the outer edge of duodenal ulcer (86.2±125.6 pg/mg tissue) was significantly (P<0.05 and 0.01) reduced as compared with that in the ulcer-free area of duodenum obtained from patients with inactive duodenal ulcer (257.1±188.2 pg/mg tissue) and from dyspeptic patients (276.8±138.3 pg/mg tissue). The results suggest that an alteration in the catecholaminergic system may be associated with one of the pathogenic factors of duodenal ulcer.This study was supported by a grant-in-aid from the Ministry of Human Health and Welfare, Tokyo.     

Sunitinib impedes brain tumor progression and reduces tumor‐induced neurodegeneration in the microenvironment

Malignant gliomas can be counted to the most devastating tumors in humans. Novel therapies do not achieve significant prolonged survival rates. The cancer cells have an impact on the surrounding vital tissue and form tumor zones, which make up the tumor microenvironment. We investigated the effects of sunitinib, a small molecule multitargeted receptor tyrosine kinase inhibitor, on constituents of the tumor microenvironment such as gliomas, astrocytes, endothelial cells, and neurons. Sunitinib has a known anti‐angiogenic effect. We found that sunitinib normalizes the aberrant tumor‐derived vasculature and reduces tumor vessel pathologies (i.e. auto‐loops). Sunitinib has only minor effects on the normal, physiological, non‐proliferating vasculature. We found that neurons and astrocytes are protected by sunitinib against glutamate‐induced cell death, whereas sunitinib acts as a toxin towards proliferating endothelial cells and tumor vessels. Moreover, sunitinib is effective in inducing glioma cell death. We determined the underlying pathways by which sunitinib operates as a toxin on gliomas and found vascular endothelial growth factor receptor 2 (VEGFR2, KDR/Flk1) as the main target to execute gliomatoxicity. The apoptosis‐inducing effect of sunitinib can be mimicked by inhibition of VEGFR2. Knockdown of VEGFR2 can, in part, foster the resistance of glioma cells to receptor tyrosine kinase inhibitors. Furthermore, sunitinib alleviates tumor‐induced neurodegeneration. Hence, we tested whether temozolomide treatment could be potentiated by sunitinib application. Here we show that sunitinib can amplify the effects of temozolomide in glioma cells. Thus, our data indicate that combined treatment with temozolomide does not abrogate the effects of sunitinib. In conclusion, we found that sunitinib acts as a gliomatoxic agent and at the same time carries out neuroprotective effects, reducing tumor‐induced neurodegeneration. Thus, this report uncovered sunitinib's actions on the brain tumor microenvironment, revealing novel aspects for adjuvant approaches and new clinical assessment criteria when applied to brain tumor patients.     

Targeting autophagy enhances the anti-tumoral action of crizotinib in ALK-positive anaplastic large cell lymphoma

Anaplastic Lymphoma Kinase-positive Anaplastic Large Cell Lymphomas (ALK+ ALCL) occur predominantly in children and young adults. Their treatment, based on aggressive chemotherapy, is not optimal since ALCL patients can still expect a 30% 2-year relapse rate. Tumor relapses are very aggressive and their underlying mechanisms are unknown. Crizotinib is the most advanced ALK tyrosine kinase inhibitor and is already used in clinics to treat ALK-associated cancers. However, crizotinib escape mechanisms have emerged, thus preventing its use in frontline ALCL therapy. The process of autophagy has been proposed as the next target for elimination of the resistance to tyrosine kinase inhibitors. In this study, we investigated whether autophagy is activated in ALCL cells submitted to ALK inactivation (using crizotinib or ALK-targeting siRNA). Classical autophagy read-outs such as autophagosome visualization/quantification by electron microscopy and LC3-B marker turn-over assays were used to demonstrate autophagy induction and flux activation upon ALK inactivation. This was demonstrated to have a cytoprotective role on cell viability and clonogenic assays following combined ALK and autophagy inhibition. Altogether, our results suggest that co-treatment with crizotinib and chloroquine (two drugs already used in clinics) could be beneficial for ALK-positive ALCL patients.     

新型组蛋白去乙酰化酶抑制剂对缺氧损伤心肌细胞的保护作用研究

目的：利用化学发光方法和细胞筛选模型,检测新型组蛋白去乙酰化酶抑制剂（ histone deacetylase inhibitor, HDACi）JZ005的抑制组蛋白去乙酰化酶（histone deacetylases,HDACs）的活性;建立氯化钴损伤的心肌细胞缺氧模型,初步探讨JZ005对缺氧损伤细胞的保护作用。方法采用脂质体转染法将含有p21启动子元件的荧光素酶报告基因真核表达载体pCI-p21-Luc转入到人胚肾细胞293中,用G418筛选获得稳定转染荧光素酶报告基因的单克隆细胞系;采用已报道的HDACi曲古抑菌素A（ trichostatina A,TSA）为阳性对照,检测细胞筛选模型的稳定性;用HDACi化学发光检测试剂盒及上述细胞筛选模型测定JZ005抑制HDACs的活性;用不同浓度的JZ005处理氯化钴缺氧损伤的大鼠胚胎心肌细胞（H9c2）,MTT法检测JZ005对缺氧损伤细胞的保护作用。免疫印迹法检测JZ005处理后正常及缺氧损伤心肌细胞组蛋白H3的乙酰化水平变化。流式细胞术检测JZ005对H9c2细胞缺氧损伤后凋亡的影响。结果建立含p21启动子元件荧光素酶报告基因的HDACi细胞筛选模型;JZ005能够显著抑制HDACs的活性,浓度50～400μmol／L,抑制率＞50％。对缺氧损伤的心肌细胞具有明显保护作用,与对照组相比,细胞存活率提高38．33％、56．00％和35．20％,同时能够上调缺氧损伤心肌细胞组蛋白H3的乙酰化水平,拮抗缺氧损伤心肌细胞的凋亡,细胞凋亡数目从对照组的12．89％分别下降到给药组（25,50和100μmol／L）的6．63％、10．56％和8．89％。结论成功建立了HDACi的细胞筛选模型;JZ005作为一种新型的HDACi ,具有明显的保护心肌细胞拮抗缺氧损伤的作用,提示JZ005有可能开发成一种治疗缺氧损伤的药物。     

Amifostine: chemotherapeutic and radiotherapeutic protective effects

Amifostine (Ethyol?, Alza Pharmaceuticals) is an inorganic thiophosphate cytoprotective agent known chemically as ethanethiol, 2-[3- aminopropyl)amino]dihydrogen phosphate. It is a prodrug of free thiol (WR-1065) that may act as a scavenger of free radicals generated in tissues exposed to cytotoxic drugs and binds to reactive metabolites of such drugs. Amifostine was originally developed as a radioprotective agent in a classified nuclear warfare project. Following declassification of the project it was evaluated as a cytoprotective agent against toxicity of the alkylating drugs and cisplatin. Differences in the alkaline phosphatase concentration of normal versus tumour tissues can result in greater conversion of amifostine in normal tissues. Inside the cell, WR-1065 provides an alternative target to DNA and RNA for the reactive molecules of alkylating or platinum agents and acts as a potent scavenger of the oxygen free radicals induced by ionizing radiation and some chemotherapy agents. Preclinical animal studies have demonstrated that the administration of amifostine protects against a variety of chemotherapy-related toxicities including cisplatin-induced nephrotoxicity, cisplatin-induced neurotoxicity, cyclophosphamide- and bleomycin-induced pulmonary toxicity and the cytotoxicities (including cardiotoxicity) induced by doxorubicin and related chemotherapeutic agents. Amifostine has been shown to protect a variety of animal species from lethal doses of radiation. Amifostine gives haematological protection from cyclophosphamide, carboplatin, mitomycin C, fotemustine and radiotherapy; renal and peripheral nerve protection from cisplatin; mucosa, skin and salivary gland protection from radiotherapy. Multiple Phase I studies were carried out with amifostine in combination with chemotherapy for various neoplasms. Appropriate doses of amifostine were found to be 740 - 910 mg/m² in single-dose regimens and 340 mg/m² in multiple-dose regimens. In radioprotection, doses are generally 200 - 350 mg/m². For all these characteristics, amifostine has been recently approved and suggested in ASCO clinical practice guidelines as a radioprotector for head and neck cancer treatment and supportive agent during cisplatin-based chemotherapy, in lymphomas and solid tumours. Moreover, its spectrum of possible applications is enlarging. As data have been provided indicating that amifostine stimulates haematopoiesis, it has been employed with intriguing results in the treatment of myelodysplastic syndromes (MDS).     

Amifostine can reduce mucosal damage after high-dose melphalan conditioning for peripheral blood progenitor cellautotransplant: a retrospective study

Amifostine (WR-2721; Ethyol) is a well-known cytoprotector, but a possible role in preventing extrahaematological toxicity after high-dose therapy (HDT) has never been investigated. We compared two historical groups of patients who either received (group A, n = 35) or did not receive (group B, n = 33) amifostine (740 mg/m2) before high-dose (HD) melphalan, followed by autologous infusion of peripheral blood progenitor cells (PBPCs). Amifostine was well tolerated at this dose level. Emesis grade 1-2 was the most important side-effect, but the interruption of infusion was never required. The incidence and median duration of severe mucositis (grade 3-4) was 21% and 0 d (range 0-11 d) in group A and 53% and 7 d (range 0-11 d) in group B. The duration of analgesic therapy was also significantly lower in group A (0 d; range 0-12) than in group B (6 d, range 0-20) (P = 0.0001). Severe diarrhoea (3% vs. 25%; P = 0.01) and emesis (9% vs. 34%; P = 0.01) were also reduced in group A in comparison with group B. No differences were observed between the two groups for haematological recovery. This retrospective study strongly suggests that amifostine can reduce severe mucositis and the use of analgesic drugs in this setting. A randomized study is warranted to confirm these preliminary results.     

Irritant-induced cyclooxygenase-2 is involved in the defense mechanism of the gastric mucosa in mice

Background. Endogenous and exogenous prostaglandins (PGs) have been shown to contribute to reducing the gastric injury caused by irritants given subse-quently. The aim of this study was to clarify whether cyclooxygenase-2 (COX-2) protein induced by pretreatment was involved in the prevention of subsequent ethanol-caused gastric injury in mice. Methods. Mice were pretreated with acidified ethanol or saline and then COX-2 protein expression in the stomach was immunohistochemically determined every 8 h. Mice were administered 95% ethanol 24 h after the acidified ethanol pretreatment, and gastric mucosal damage was evaluated macroscopically and histologically. The effects of NS-398 or indomethacin on the 95% ethanol-caused damage were also examined. Results. Acidified ethanol pretreatment induced COX-2 protein expression in lamina propria macrophages of the gastric mucosa, with a peak level 24 h after the pretreatment. The 95% ethanol treatment caused gastric mucosal damage. The degree of the damage was not different between mice pretreated with acidified ethanol and those pretreated with saline. However, NS-398 aggravated the ethanol-caused damage only in mice pretreated with acidified ethanol, while indomethacin aggravated the damage, evaluated histologically, irrespective of the pretreatment. Conclusions. Pretreatment-induced COX-2, in addition to COX-1, seemed to be involved in the defense mechanism through minimizing the damage caused by a subsequent irritant. Received: October 16, 2000 / Accepted: September 14, 2001