CysLT1 signal transduction in differentiated U937 cells involves the activation of the small GTP-binding protein Ras

We investigated the signal transduction pathway(s) of leukotriene D(4) (LTD(4)) in the human promonocytic U937 cells, a cell line known to constitutively express CysLT(1) receptors. Herein, we demonstrate that LTD(4) specifically acts on a CysLT(1) receptor to dose-dependently increase (three to five-fold over basal) RasGTP through a G(i/o) protein. In fact, while cytosolic Ca(2+) ([Ca(2+)](i)) increase was only partially sensitive to pertussis toxin (PTx), Ras activation was almost completely inhibited by the same toxin. Furthermore, the phospholipase C (PLC) inhibitor U73122 completely inhibited both [Ca(2+)](i) and RasGTP increase, suggesting that in these cells PLC is the point of convergence for both PTx insensitive and sensitive pathways leading to [Ca(2+)](i) release and Ras activation. Indeed, chelating intracellular Ca(2+) strongly (>70%) prevented LTD(4)-induced Ras activation, indicating that this ion plays an essential role for CysLT(1)-induced downstream signaling in differentiated U937 (dU937) cells. In addition, while Src did not appear to be substantially involved in CysLT(1)-induced signaling, genistein was able to partially inhibit LTD(4)-induced [Ca(2+)](i) transient ( approximately 34%) and almost completely prevented Ras activation (>90%), suggesting a potential role for other Ca(2+)-dependent tyrosine kinases in LTD(4)-induced signaling. Finally, agonist-induced CysLT(1) stimulation was followed by a specific extracellular regulated kinase (ERK) 1/2 phosphorylation, an event with a pharmacological profile similar to that of Ras activation, partially ( approximately 40%) sensitive to Clostridium sordellii lethal toxin and totally blocked by PTx. In conclusion, LTD(4)-induced CysLT(1) receptor activation in dU937 cells leads to Ras activation and ERK phosphorylation mostly through a PTx-sensitive G(i/o) protein, PLC, and Ca(2+)-dependent tyrosine kinase(s).     

Transinactivation of the epidermal growth factor receptor tyrosine kinase and focal adhesion kinase phosphorylation by dietary flavonoids: effect on invasive potential of human carcinoma cells

Focal adhesion kinase (FAK), a member of a growing family of structurally distinct protein tyrosine kinases (PTK), has been linked to specific phosphorylation events, and the elevation of FAK activity in human carcinoma cells correlated with increased invasive potential. Transactivation of the epidermal growth factor receptor (EGFR) tyrosine kinase activity is proposed to stimulate cell migration and the subsequent activation of downstream signaling pathways. Quercetin (Qu) and luteolin (Lu), are potent PTK inhibitors as well as putative chemopreventive agents. The present work, we demonstrate that Qu and Lu at concentration of 20 microM transinactivated EGFR tyrosine kinase activity with marked reduction in phosphotyrosyl level of 170, 125, 65, 60 and 42 kDa cellular proteins, and induced apoptosis in MiaPaCa-2 cells. The 125 kDa protein was further identified as a FAK by immunoprecipitation and immunoblotting analyses. Tumor cells treated with Lu or Qu dampened the phosphorylation of FAK. In addition, our data clearly demonstrated that tumor cells responded to Qu and Lu by parallel reductions in the levels of phosphorylated FAK and the secreted matrix metalloproteinase (MMP) that may lead to the suppression of invasive potential and cell migration in vitro. While the molecular mechanism of FAK regulation of MMP secretion in tumor cells remains unclear, our results suggested that blockade of the EGFR-signaling pathway may contributed to the net effect. As suggested in the current study, targeting EGFR and FAK with the objective of modulating their regulatory pathways could offer prospects for the treatment of EGFR-responsive cancers in the future.     

Differential expression of the non-receptor tyrosine kinase BRK in oral squamous cell carcinoma and normal oral epithelium

BRK is a non-receptor tyrosine kinase whose functional role is poorly understood. Although it is an epithelial specific kinase, its expression appears to be tissue specific. To date, little is known about BRK expression in human oral epithelium. We investigated expression of BRK in human oral squamous cell carcinomas (OSCC) and normal oral epithelium (NOE) using immunohistochemistry, laser confocal microscopy and Western blotting. The subcellular localization of BRK was identified by confocal microscopy and Western blotting of nuclear and cytoplasmic extracts from these cells. The results indicate that NOE express higher levels of BRK compared with OSCC cells. In NOE and moderately differentiated OSCC cells, BRK was localized in the nucleus and cytoplasm. However, in poorly differentiated OSCC cells, BRK was localized in perinuclear regions. These results suggest that BRK expression differs in normal and OSCC which may reflect a possible functional involvement in OSCC.     

用PTK及机械方法去除角膜上皮对PRK进行观察

目的：分别使用光性治疗性角膜切除术（PTK）和机械方法去除角膜上皮，观察光性屈光性角膜切削术（PRK）术后症状、角膜上皮愈合及haze发生情况。方法：2001-02～2003-03期间对122人214眼屈光度在-1．50D～-5．00D之间的近视病人分别使用PTK和机械方法去除角膜上皮行PRK手术。结果：PTK去除角膜上皮较机械方法去除角膜上皮，病人术后症状明显减轻，前者角膜上皮较后者愈合快，且无一例haze发生，而后者发生5例。结论：PTK去除角膜上皮行PRK手术，术后症状轻、角膜上皮愈合快及haze发生少，值得推广应用。     

Antivascular therapy of oral tongue squamous cell carcinoma with PTK787

OBJECTIVES/HYPOTHESIS: Vascular endothelial growth factor (VEGF) is an important mediator in tumor vascularization, growth, and metastasis. We investigated whether blockade of the VEGF receptor (VEGF-R) signaling pathway by the tyrosine kinase inhibitor PTK787 combined with CPT-11, a semisynthetic camptothecin analogue, can inhibit the tumor growth and angiogenesis of squamous cell carcinoma of the oral tongue in an orthotopic nude mouse model. METHODS: JMAR human oral squamous cell carcinoma cells were injected into the tongues of nude mice. Seven days later, the mice were randomized to receive a placebo, daily oral PTK787, weekly CPT-11 injection, or PTK787 plus CPT-11. After 4 weeks of treatment, the mice underwent necropsy, and the tongue tumors, cervical lymph nodes, and lungs were removed for immunohistochemical analyses. RESULTS: CPT-11, PTK787, and PTK787 plus CPT-11 significantly decreased tumor volumes and prolonged survival. The combination treatment group had the most significant decrease in volume and increase in survival. PTK787 alone or in combination with CPT-11 reduced the phosphorylation of VEGF-R in tumor cells and tumor-associated endothelial cells, was associated with decreased microvessel density, a decreased proliferative index, and an increased apoptotic index. PTK787 alone or the combination therapy resulted in apoptosis of both tumor cells and tumor-associated endothelial cells. CONCLUSIONS: These results suggest that targeting VEGF-R tyrosine kinase activity can be an effective therapeutic approach in squamous cell carcinoma of the oral tongue.     

增生性瘢痕和瘢痕疙瘩中PTK活性测定

目的测定增生性瘢痕和瘢痕疙瘩组织中PTK活性变化,探讨PTK在瘢痕形成中的作用。方法利用活化的PTK催化底物多肽磷酸化,再计数底物中掺入32P的放射活性的原理,测定增生性瘢痕、瘢痕疙瘩、成熟瘢痕和正常皮肤组织中PTK活性。结果增生性瘢痕和瘢痕疙瘩组织中PTK的活性显著高于正常成熟瘢痕和正常皮肤（P＜0.001,分别高出正常皮肤150.80%和313.80%）,瘢痕疙瘩高于增生性瘢痕（P＜0.001,高出65.01%）而成熟瘢痕和正常皮肤间没有差异（P＞0.05）。结论瘢痕组织中PTK活性升高且与增生程度相关,PTK介导生长刺激的信号转导使细胞增殖和合成物质的功能增强而发生瘢痕增生。     

准分子激光治疗性角膜切削术治疗角膜浅层病变的疗效观察

目的 :观察准分子激光治疗性角膜切削术 (PTK)对角膜浅层病变的疗效。方法 :利用PTK治疗 10例 11眼角膜病患者 ,其中男 4例 4眼 ,女 6例 7眼 ,平均年龄 6 5岁 ,术后随访 18个月。其中大泡性角膜病变 4例 4眼 ,复发性胬肉致角膜云翳 2例 2眼 ,带状角膜变性 1例 2眼 ,颗粒性角膜变性 1例 1眼 ,细菌性角膜炎致角膜云翳 1例 1眼 ,复发性角膜上皮糜烂 1例 1眼。结果 :术后视力提高 2行以上者 4例 5眼 ,提高 1行者 2例 2眼。刺激症状均明显改善。结论 :PTK治疗浅层角膜病变方法简单易行、安全可靠 ,值得推广     

Clinical and Genetic Aspects of the TGFBI-associated Corneal Dystrophies

Corneal dystrophies are a group of inherited disorders localized to various layers of the cornea that affect corneal transparency and visual acuity. The deposition of insoluble protein materials in the form of extracellular deposits or intracellular cysts is pathognomic. Mutations in TGFBI are responsible for superficial and stromal corneal dystrophies. The gene product, transforming growth factor β induced protein (TGFBIp) accumulates as insoluble deposits in various forms. The severity, clinicopathogenic variations, age of the onset, and location of the deposits depend on the type of amino acid alterations in the protein. Until 2006, 38 different pathogenic mutants were reported for the TGFBI-associated corneal dystrophies. This number has increased to 63 mutants, reported in more than 30 countries. There is no effective treatment to prevent, halt, or reverse the deposition of TGFBIp. This review presents a complete mutation update, classification of phenotypes, comprehensive reported incidents of various mutations, and current treatment options and their shortcomings. Future research directions and possible approaches to inhibiting disease progression are discussed.     

Pathogenesis and treatments of TGFBI corneal dystrophies

Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.     

Combined inhibitors of angiogenesis and histone deacetylase: efficacy in rat hepatoma

AIM:To evaluate the antitumoral effect of combined inhibitors of angiogenesis and histone deacetylases in an experimental rat hepatoma model.METHODS:MH7777A hepatoma cells were injected into the liver of male Buffalo rats.After 7 d treatment with the vascular endothelial growth factor receptor antagonist PTK787/ZK222584(PTK/ZK),the histone deacetylase inhibitor MS-275,tamoxifen(TAM) and/or retinoic acid was initiated(n ≥ 8 animals/group).Natural tumor development was shown in untreated control groups(contro...