Taxol resistance and its reversal by synthetic isoprenoids in human bladder cancer cell line.

PURPOSE: We investigated the mechanism of action of reversal agents for taxol-resistance in bladder cancers. MATERIALS AND METHODS: We isolated a taxol-resistant cell line (KK47/TX30) from a human KK47 bladder cancer cell line (KK47/WT). We characterized KK47/TX30 cells and screened reversal agents for taxol-resistance. RESULTS: KK47/TX30 cells exhibited approximately 700-fold resistance to taxol and cross-resistance to Vinca alkaloids and topoisomerase II inhibitors. Western blot analysis demonstrated P-glycoprotein (P-gp) overexpression in taxol-resistant cells. Drug accumulation and efflux studies showed that the decreased taxol accumulation in the resistant cell line was due to enhanced taxol efflux. We synthesized 31 isoprenoids based on the structure of N-solanesyl-N,N'-bis(3,4-dimethoxybenzyl)ethylenediamine (SDB), which could completely reverse multidrug resistance (MDR) as shown previously. Among those examined, trans-N,N'-bis(3,4-dimethoxybenzyl)-N-solanesyl-1,2-diaminocyclohexane (N-5228) could completely reverse taxol-resistance in KK47/TX30 cells. Results of a structure-activity relationship study of isoprenoids suggested that the following structural features were important for overcoming taxol-resistance: (1) a basic structure of 8 to 10 isoprene units, (2) a cyclohexane ring or benzene ring within the framework, (3) two cationic sites in close proximity to each other, and (4) a benzyl group with 3,4-dimethoxy functionalities with moderate electron-donation. CONCLUSIONS: Taxol-resistance was primarily mediated by P-gp overexpression in KK47/TX30 cells. One of the synthetic isoprenoids, N-5228 could completely reverse taxol-resistance in KK47/TX30 cells.

Overexpression of cyclooxygenase-2 in high-grade human transitional cell carcinoma of the upper urinary tract.

OBJECTIVE: To examine cyclooxygenase (COX)-2 expression (a key enzyme in the synthesis of prostaglandins, and involved in carcinogenesis of human epithelial tumours) in human transitional cell carcinomas (TCCs) of the renal pelvis and ureter, and to determine whether COX-2 expression correlates with the clinicopathological characteristics of the disease. MATERIALS AND METHODS: Specimens from 144 patients with TCC of the upper urinary tract who had undergone nephroureterectomy were analysed immunohistochemically, and 23 were also analysed by immunoblotting. RESULTS: Immunoblot analysis showed COX-2 immunoreactivity in 17 (74%) of 23 tumours, but not in normal transitional epithelium. COX-2 was localized to the cytoplasm of cancer cells and expressed in 108 (75%) of 144 tumours, as assessed by immunohistochemical analysis. COX-2 expression correlated with tumour grade (P < 0.008), being detected in one of nine grade 1, 77 (79%) of 97 grade 2 and 30 (79%) of 38 grade 3 tumours. Other variables including tumour stage were not associated with COX-2 expression. CONCLUSIONS: We show for the first time that COX-2 is frequently expressed in TCC of the upper urinary tract and is associated with the degree of tumour cell differentiation, indicating that COX-2 may be involved in TCC carcinogenesis at an early and/or late stage, and could be a useful target for chemoprevention of this type of cancer.

Expression of thymidine phosphorylase as an indicator of poor prognosis for patients with transitional cell carcinoma of the bladder.

BACKGROUND: Thymidine phosphorylase (TP), which is identical to platelet-derived endothelial cell growth factor (PD-ECGF), stimulates chemotaxis of endothelial cells and is involved in the angiogenesis of human solid tumors. METHODS: The activity and expression of TP were examined in human transitional cell carcinomas (TCCs) of the bladder, and their association with clinicopathologic findings was determined. The activity of the enzyme in 37 TCCs and 12 adjacent nonneoplastic tissues was measured spectrophotometrically. The expression of TP was also examined by immunoblotting. Immunohistochemical analysis was performed on 108 TCCs. RESULTS: TP activity in the carcinomas was higher than that in adjacent normal tissues (P = 0.002). TP activity in Grade 3 tumors or those classified as pT2-4 was higher than in Grade 1 and 2 tumors (P = 0.017) or those classified as pT1 (P = 0.007). The level of expression of TP detected by immunoblotting correlated well with TP activity. Immunohistochemical analyses showed that 62 of 108 cases (57.4%) were TP positive. There was a significant correlation between TP expression and histologic grade, infiltration pattern, local invasion, and lymph node metastasis. TP expression as a prognostic variable was studied using the Cox proportional hazards model. TP overexpression was an independent prognostic factor, as were lymph node metastasis and local invasion. CONCLUSIONS: These findings suggest that TP activity and its level of expression influence the progression of TCC and the prognoses of patients with this disease.

Expression of vascular endothelial growth factor in patients with testicular germ cell tumors as an indicator of metastatic disease.

BACKGROUND: Angiogenesis is essential for tumor growth and metastasis. Vascular endothelial growth factor (VEGF) and thymidine phosphorylase (TP)/platelet-derived endothelial cell growth factor (PD-ECGF) are involved in increased angiogenic activity and disease progression in solid tumors. However, there is no information regarding the association of these angiogenic factors with clinicopathologic findings in testicular germ cell tumors (GCTs). METHODS: The authors examined the expression of VEGF and TP as well as microvessel density in GCTs and their association with clinicopathologic findings. Expression of VEGF and TP and microvessel density were examined immunohistochemically in 80 GCTs, including 33 seminomas (25 tumors with organ-confined disease and 8 with metastasis) and 47 nonseminomatous testicular GCTs (NSGCTs) (20 tumors with organ-confined disease and 27 with metastasis). Expression of VEGF also was examined in four GCTs and one nonneoplastic testis by immunoblotting. RESULTS: VEGF protein was expressed more highly in GCTs compared with nonneoplastic testes. VEGF expression in GCTs was correlated significantly with microvessel count (P < 0.001). Both VEGF expression and microvessel count were correlated with metastasis in seminoma (P = 0.008 and P < 0.001, respectively), but only VEGF expression was identified as statistically significant by multiple regression analysis (P = 0.006). Conversely, four variables (VEGF expression, microvessel count, the presence of venous invasion, and the presence of embryonal carcinoma elements in the primary tumor) were correlated with metastasis in NSGCT (P < 0.001, P < 0.001, P = 0.004, and P = 0.029, respectively). However, multiple regression analysis revealed that only VEGF expression and microvessel count were significant factors for metastasis (P < 0.007 and P < 0.001, respectively). In contrast, high levels of TP were observed in infiltrating cells, but not in the majority of cancer cells. CONCLUSIONS: The findings of the current study suggest that VEGF expression is involved in tumor development, angiogenesis, and metastasis in GCT.

Natural killing activity is associated with progression of gastric cancer.

Previously, we proposed a new analysis of natural killing activity, in which an individual effector/target cell ratio was employed for comparison according to the peripheral number of effector cells. In 51 patients with gastric cancer, the activity was studied using that modified analysis. Natural killing activity was activated in patients with early cancer, where tumor-cell invasion was restricted to the mucosa or the submucosa, even though in well-differentiated adenocarcinoma with invasion of the mucosa alone, the activity remained at the level of controls. In contrast, the activity in advanced cancer, where tumor cells infiltrated beyond the submucosa, came to be inactivated as the cancer progressed. These facts suggest that natural killing activity in patients with gastric cancer is closely associated with tumor invasion and that reactive activation of the activity against tumor is induced, at least, in some patients with early stage.

A case of extragenital choriocarcinoma in the jejunum.

A case of extragenital choriocarcinoma which produces human chorionic gonadotropin (HCG) in the small intestine of a 48-yr-old Japanese women is reported. Only seven such cases have been reported. The patient complained of postprandial upper abdominal pain and vomiting of 5 months' duration. Nine years before, right upper lobectomy was performed because of lung undifferentiated carcinoma. Double-contrast examination of the small intestine showed irregular ulceration in the lower jejunum. Celiac angiography demonstrated a hypervascular tumor stain in the branch of the jejunal artery. The serum HCG level was elevated. Gynecological examination revealed nothing abnormal. A small intestinal neoplasm was diagnosed, and a partial resection of the jejunum was performed. Endoscopy on the operating table showed a large, irregularly shaped sessile ulcer. Histologically the tumor was diagnosed as choriocarcinoma, composed of syncytiotrophoblastic cells and cytotrophoblastic cells. Immunohistochemical staining for HCG was positive. No metastasis was present. Although extragenital choriocarcinoma in the small intestine is rare, it should be included in the differential diagnosis of small intestinal neoplasm.

Diabetes insipidus after traumata of two extremes in severity.

Two patients with post-traumatic diabetes insipidus (DI) are reported. One had suffered a fatal injury and the other a mild contusion without amnesia before DI developed. These two instances exemplify the wide spectrum of post-traumatic DI and, hence, the importance of ruling out DI even afer a mild closed-head injury.

Effect of somatostatin and its analogs on histamine-stimulated cAMP production in isolated guinea pig gastric glands.

The effect of somatostatin-14 (ss-14), somatostatin-28 (ss-28), and [D-trp8]somatostatin-14 ([ D-trp8]ss-14) on both histamine-stimulated cellular cAMP production and [3H]-cimetidine binding on plasma membranes in isolated guinea pig gastric glands was investigated. These three peptides partially inhibited (approximately 50% maximally) the increase of cAMP production stimulated by histamine. There was no inhibition of [3H]-cimetidine binding on plasma membranes from these isolated gastric glands. These results indicate that somatostatin acts directly on parietal cells and inhibits histamine-stimulated cAMP production with no influence on H2 receptor in histamine stimulated gastric secretion. Inhibitory potency of somatostatin and its analogs against histamine-stimulation may be equal at the cellular level.