Clinical significance of pyrimidine nucleoside phosphorylase (PyNPase) in breast cancer

To clarify the clinical significance of pyrimidine nucleoside phosphorylase (PyNPase) activity in breast cancer, we examined the possible correlation of PyNPase activity to clinicopathological features and prognosis in twenty-one patients with primary breast cancer from April 2000 to December 2001. Flow signals of tumors were analyzed by Power Doppler sonography (PDUS), and maximal velocity (V(max)) was calculated. PyNPase activity of resected specimens was assayed by ELISA method. PyNPase activities in resected cancerous tissue were 156.9+/-63.5 unit/mg (mean+/-SD), which were significantly higher than that in normal tissue (19.0+/-18.1 unit/mg, p<0.0001). PyNPase activity was positively correlated with tumor size (r=0.496, p=0.026) and V(max) (r=0.498, p=0.021). The disease free survival rate was significantly lower in the high PyNPase activity group than in the low PyNPase activity group. In overall survival rate, there was no significant difference between the high and low PyNPase activity groups. In the multivariate analysis, PyNPase activity was an independent predictor of postoperative recurrence (p=0.032). We suggest that PyNPase activity is associated with progression and proliferation of breast cancer, and that it may be useful for prediction of the prognosis.     

Perioperative allogeneic blood transfusion, the related cytokine response and long-term survival after potentially curative resection of colorectal cancer

AimsIt is still debated whether perioperative blood transfusion alters the incidence of disease recurrence or otherwise affects the prognosis after curative resection of malignant tumours. We conducted a prospective observational study of patients with colorectal cancer to provide data on the effect of blood transfusion and the related perioperative cytokine response on long-term prognosis.Materials and methodsPerioperative blood samples were obtained from 117 patients with colorectal cancer undergoing potentially curative resection. Factors associated with perioperative blood transfusion were assessed, and their relationship with early postoperative systemic responses of tumour growth factors and long-term prognosis were evaluated.ResultsIndependent factors associated with perioperative blood transfusion were preoperative anaemia, operative blood loss and the development of postoperative infectious complication. The patients receiving transfusions were subdivided according to the independent factors. Group A comprised 19 patients who received blood transfusions because of preoperative anaemia and Group B comprised 16 patients who received blood transfusions because of excessive operative blood loss. Group B patients showed exaggerated postoperative systemic induction of interleukin (IL)-6 and IL-6-triggered tumour growth factors, such as hepatocyte growth factor and vascular cell adhesion molecule-1. Intraoperative blood transfusion under intense surgical stress was associated with poor prognosis, whereas preoperative blood transfusion for correcting anaemia or intraoperative blood transfusion under less invasive surgery was not associated with survival. Multivariate analysis using the Cox proportional hazards method showed that a significant independent risk was demonstrated for blood transfusion, T stage, lymph-node metastasis and perioperative peak levels of IL-6.ConclusionBlood transfusion and intense surgical stress might synergistically affect the long-term prognosis after curative resection of colorectal cancer. Postoperative exaggerated systemic inductions of IL-6 may indicate the critical situation that could lead to disease recurrence.     

Cytokinesis regulator ECT2 changes its conformation through phosphorylation at Thr-341 in G2/M phase

The Rho activator ECT2 functions as a key regulator in cytokinesis. ECT2 is phosphorylated during G2/M phase, but the physiological significance of this event is not well known. In this study, we show that phosphorylation of ECT2 at threonine-341 (T341) affects the autoregulatory mechanism of ECT2. In G2/M phase, ECT2 was phosphorylated at T341 most likely by Cyclin B/Cyclin-dependent kinase 1 (Cdk1), and then dephosphorylated before cytokinesis. Depletion of ECT2 by RNA interference (RNAi) efficiently induced multinucleate cells. Expression of the phospho-deficient mutant of ECT2 at T341 suppressed the multinucleation induced by RNAi to ECT2, indicating that ECT2 is biologically active even when it is not phosphorylated at T341. However, the phospho-mimic mutation at T341 weakly stimulates the catalytic activity of ECT2 as detected by serum response element reporter gene assays. As T341 is located at the hinge region of the N-terminal regulatory domain and C-terminal catalytic domain, phosphorylation of T341 may help accessing downstream signaling molecules to further activate ECT2. We found that the phospho-mimic mutation T341D increases binding with itself or the N-terminal half of ECT2. These results suggest a conformational change of ECT2 upon phosphorylation at T341. Therefore, ECT2 activity might be regulated by the phosphorylation status of T341. We propose that T341 phosphorylation by Cyclin B/Cdk1 could be a trigger for further activation of ECT2.     

Lysocellin, a metabolite of the novel drug 'alopestatin', induces G1 arrest and prevents cytotoxicity induced by etoposide

We report here that lysocellin, a polyether antibiotic from a streptomycete, induces G1 phase arrest in human osteosarcoma MG63 cells. Lysocellin up-regulates p21WAF1/Cip1 and down-regulates cyclin D1 at the mRNA level. In addition, cyclin D1 is down-regulated by the proteasome-dependent signal pathway in MG63 cells. In drug combination studies, we found that lysocellin treatment weakened the cytotoxic activity of etoposide in MG63 cells using a colony-formation assay. To study the in vivo efficacy of lysocellin, we isolated a novel compound related to lysocellin from the same streptomycete, and found that the novel drug is converted to lysocellin in vivo and decreases etoposide-induced alopecia in a neonatal rat model. We raise the possibility that this novel drug, named 'alopestatin', may be a promising agent against alopecia.     

Expression level of ECT2 proto-oncogene correlates with prognosis in glioma patients

The ECT2 (epithelial cell transforming sequence 2) proto-oncogene encodes a guanine nucleotide exchange factor for Rho GTPases, and regulates cytokinesis. ECT2 plays a critical role in Rho activation during cytokinesis, and thus may play a role in the pathogenesis of glioma. In this study, we investigated relationships between ECT2 expression, tumor histology, and prognosis in glioma patients. ECT2 mRNA expression was examined using quantitative real-time PCR, while its protein expression was examined by immunohistochemistry of 54 glioma tissue samples. Expressions of ECT2 mRNA and protein were markedly increased in high-grade gliomas compared to low-grade gliomas. Patients in whom expression of ECT2 mRNA and protein in tumor tissues was the lowest survived longer than patients who had higher expression. In vitro, ECT2 siRNA inhibited glioma cell proliferation and invasion. These data suggest that increased expression of ECT2 contribute to promotion of tumor invasiveness and progression, implying that evaluation of ECT2 expression is a prognostic marker for glioma patients.     

Gene expression profiling of breast cancer

Numerous genes are controlled by complex regulatory networks and involved in the development and progression of breast cancer, and these genes are the key factors determining each characteristic of the tumor. Gene expression profiling, a large scale analysis of gene expression, has created new possibilities for the molecular characterization of cancer. Systematic analysis of expression patterns of thousands of genes in tumor cells using DNA microarrays and correlation of these patterns to specific features of phenotypic variation may provide the basis for an improved taxonomy of cancer. These profiles have the potential to explain the genetic heterogeneity of breast cancer and allow treatment strategies to be planned in accordance with their probability of success in individual patients.     

Usefulness of contrast enhanced-MRI in the diagnosis of unicystic ameloblastoma

The radiographic features of unicystic ameloblastoma (UA) are typically unilocular and round area of radiolucency. Therefore, this type of lesion is often misdiagnosed as an odontogenic keratocyst or a dentigerous cyst. UA should be differentiated from odontogenic cysts because the former have a higher rate of recurrence than the latter. In the present study, we performed contrast enhanced-MRI (CE-MRI) to diagnose 13 cases of unilocular, round radiolucent lesions visualized on panoramic radiograph and/or CT. In the cases of UA, low signal intensity was observed on T1-weighted images (WIs), and a markedly high signal intensity was observed on T2-WIs; moreover, relatively thick rim-enhancement with/without small intraluminal nodules was observed upon CE-T1WIs. CE-MRI was considered useful in the diagnosis of UA, as characteristic features of this type of lesion i.e., thick enhancement of the tumor wall and small intraluminal nodules were detected only by CE-MRI in the present study.     

Immunohistochemical localization of D-aspartate in islets of Langerhans

D-Aspartate is a putative modulator of neuroendocrine functions, and is present in various neuroendocrine cells as well as the central nervous system. Here we show that the islet of Langerhans is a D-aspartate-containing endocrine organ. Immunohistochemical analysis with specific antibodies against D-aspartate indicated that D-aspartate is present in all islet cells, and predominantly present in alpha cells and a subpopulation of F-cells. Since these cells are glutamatergic in nature, it is possible that D-aspartate is involved in the glutamate signaling pathways in the islets.     

Construction of several human-derived stable cell lines displaying distinct profiles of CYP3A4 induction

Cell lines which stably express reporter proteins through CYP3A4 gene activation have been developed for use in predicting CYP3A4 induction. Twelve clones showing distinct profiles on chemical-induced response were isolated. Among them, two clones showing high response for CYP3A4 inducers, namely clone 3-1-10 and 3-1-20, were further evaluated for their sensitivities, reproducibilities and applicabilities to predict CYP3A4 induction in human. Clone 3-1-10 showed higher response to rifampicin than to clotrimazole, whereas clone 3-1-20 had rather higher response to clotrimazole. Optimal plating density and highly reproducible response were observed at the range of 1.65-5.0 x 10(4) cell/cm2. Clear induction responses of more than ten chemicals were observed in both cell lines. The reporter activity was further dramatically increased after an introduction of human PXR. Induction with rifampicin was, however, not much altered between the absence and presence of hPXR. The luciferase activity remained unaltered and showed little fluctuation during the culture for more than 6 months. Due to the strikingly high sensitivity and reproducibility of this system, as compared to previously published systems, these HepG2-derived cell lines showing distinct response profiles as developed in the present study will offer high advantages for chemical screening of CYP3A4 inducibility.