De-Lai Qiu

Lack of Evidence for the Association of E-Cadherin Gene Polymorphism with Increased Risk or Progression of Prostate Cancer

Background: E-cadherin is an epithelial cell adhesion molecule, and decreased E-cadherin expression in human prostate cancer is associated with tumor grade and advanced clinical stage. A –160 C→A polymorphism in the promoter region of E-cadherin has been shown to decrease gene transcription. This allelic variation may be a potential genetic marker that can help identify those individuals at higher risk for invasive/metastatic disease. Materials and Methods: We studied the effect of E-cadherin gene polymorphism on prostate cancer susceptibility in a case control study of 219 prostate cancer patients and 219 male controls, to determine whether this polymorphism is a biomarker for the risk and how aggressive the disease is. Results: The genotype frequencies in the prostate cancer group were C/C: 0.607, C/A: 0.352, A/A: 0.041, and in the control group C/C: 0.671, C/A: 0.301, A/A: 0.027. A significant difference between the two groups was not found (p = 0.34), and the adjusted OR for A/A genotype was not statistically significant (OR = 1.66, 95% CI 0.58–4.78). Subdividing prostate cancer according to tumor differentiation and stage, we found no association between E-cadherin polymorphism and poor differentiation and invasiveness of prostate cancer. Conclusions: These data do not support an association between the E-cadherin genotype and the occurrence or progression of prostate cancer in Japanese populations.

Effects of cytochrome P450 (CYP) 2A6 gene deletion and CYP2E1 genotypes on gastric adenocarcinoma

Cytochrome P450 (CYP) 2A6 and CYP2E1 are enzymes with a high ability to activate a nitrosamine, 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone (NNK), to its potent and ultimate carcinogens. The polymorphic CYP2A6 and CYP2E1 have been implicated in increased susceptibility to certain malignancies. In our study, 120 Japanese patients with gastric adenocarcinoma and 158 healthy controls were compared for frequencies of CYP2A6 and CYP2E1 genotypes. The frequency with which the subjects carried homozygotes of the CYP2A6 gene deletion allele, which causes lack of the enzyme activity, was significantly higher in the gastric cancer patients than in the healthy control subjects (OR = 3.14, 95% confidence interval (95% CI) = 1.05–9.41). Subdividing gastric adenocarcinoma according to tumor differentiation, patients with the well‐differentiated type were 4.9‐fold more likely to have the CYP2A6 homozygote deletion genotype (OR = 4.91, 95% CI 1.17–20.52). Stratifying by smoking status, we did not find the risk of CYP2A6 gene deletion allele in gastric adenocarcinoma. The CYP2E1 polymorphism detected by RsaI was not significantly different between gastric adenocarcinoma patients (40.8%) and the control population (44.3%). No statistically significant changes were observed when the CYP2E1 genotype was examined relative to tumor differentiation and smoking status. These results suggest that the CTY2A6 deletion is associated with gastric adenocarcinoma among Japanese populations.

Central stresscopin modulates cardiovascular function through the adrenal medulla in conscious rats.

Stresscopin (SCP or urocortin III), a member of the corticotropin-releasing factor (CRF) neuropeptide family, is a high-affinity ligand for the type 2 CRF receptor (CRF(2)). When administered peripherally, SCP suppresses food intake, delays gastric emptying and decreases heat-induced edema. Central administration of CRF produces marked hypertension and increased plasma catecholamine. However, the effects of SCP on the cardiovascular system are unknown. Thus, the present study compared the effects of intracerebroventricular (i.c.v.) administration of CRF and SCP on cardiovascular function. Central administration of SCP (0.05 or 0.5 nmol) elicited transient increases in mean arterial blood pressure (MABP) and heart rate (HR), and the higher dose of SCP (0.5 nmol) resulted in increased plasma epinephrine. In contrast, central administration of CRF provoked long-lasting increases in MABP, HR and plasma catecholamine levels (norepinephrine and epinephrine). Intravenously administered CRF and SCP (0.5 nmol) did not elicit significant changes in MABP and HR. Therefore, these data suggest that centrally administered SCP modulates cardiovascular function, likely through the sympatho-adrenal-medullary (SAM) system.

The effects of centrally administered dexmedetomidine on cardiovascular and sympathetic function in conscious rats.

BACKGROUND:The α2-receptor is expressed in the brain, including the hypothalamus, where it is implicated in autonomic nervous system control. The effects of systemic administration of dexmedetomidine (DEX) on cardiovascular responses are well known; however, little is known about the effects of central administration of DEX on cardiovascular responses in conscious animals. In this study, we explored the effects and the mechanism of intracerebroventricularly (icv) administered DEX on cardiovascular responses and sympathetic nerve activity in conscious, unrestrained rats. METHODS:We administered DEX (0.5, 1, and 2 &mgr;g/kg) icv and measured the mean arterial blood pressure (MAP), heart rate (HR), and plasma catecholamine in conscious rats (n = 58). Rats were also administered atropine (n = 8), propranolol (n = 8), or hexamethonium (n = 8) to assess the influence of vagal or sympathetic efferent activity in the DEX-induced responses. Some of the rats underwent carotid sinus and aortic nerve denervation to exclude the effect of the baroreceptor reflex. RESULTS:Intracerebroventricular administration of DEX dose-dependently decreased MAP, HR, and plasma norepinephrine. Large dose of DEX decreased plasma epinephrine. The amplitude of MAP reduction induced by DEX was reduced by hexamethonium or propranolol. The amplitude of HR reduction was reduced by atropine or propranolol. The amplitude of MAP and HR reduction induced by DEX were smaller in hexamethonium-pretreatment rats than in intact ones. The amplitude of MAP and HR reduction induced by DEX were larger in sinus and aortic nerve denervation rats than in intact ones. CONCLUSIONS:These results indicate that icv administration of DEX decreases MAP by sympathetic inhibition and decreases HR by sympathetic inhibition and vagal stimulation.

The α1D-adrenergic receptor modulates cardiovascular and drinking responses to central salt loading in mice

To characterize the involvement of specific alpha(1)-adrenergic receptor (alpha(1)-AR) subtypes in hypertension, parameters related to central salt- or angiotensin II (ANG II)-induced hypertension were investigated in alpha(1D)-AR-deficient mice (knockout). Baseline daily water intake and food intake were larger in alpha(1D)(-/-) mice than in alpha(1D)(+/+) mice. Intracerebroventricular (i.c.v.) administration of NaCl (0.67 M NaCl, 1 microl) elicited smaller increases in mean arterial blood pressure (MABP), heart rate, and water intake in alpha(1D)(-/-) mice than it did in alpha(1D)(+/+) mice. I.c.v. administration of ANG II (10 pmol) resulted in increases in MABP and water intake that were similar in alpha(1D)(-/-) mice and alpha(1D)(+/+) mice. These results suggest that alpha(1D)-AR is, at least in part, involved in central salt-induced but not ANG II-induced hypertension and water intake.

Single-unit activity of paraventricular nucleus neurons in response to intero- and exteroceptive stressors in conscious, freely moving rats.

Extracellular recordings of 114 neurons in the hypothalamic paraventricular nucleus (PVN) of conscious, freely moving male rats were performed using a movable electrode system. Single-unit activities were examined for their spontaneous firing patterns and responses to intero- and exteroceptive stressors, including disturbance in arterial blood pressure, water deprivation, air-jet stimulation, and systemic administration of cholecystokinin-8 (CCK). PVN neurons were assigned to one of two groups on the basis of their spontaneous firing patterns: phasic (n=29) and non-phasic (n=85). Intravenous (i.v.) administration of phenylephrine (8 microg/kg) resulted in the inhibition of a greater percentage of phasic-type (88.9%; 24/27) than non-phasic-type neurons (14.9%; 11/74). Most phasic-type neurons showed excitation in response to i.v. administration of sodium nitroprusside (20 microg/kg, 66.7%; 18/27) and water deprivation (15 h, 77.8%; 7/9) when compared to non-phasic-type neurons. Conversely, a greater number of non-phasic-type neurons showed excitation in response to air-jet stimulation (5 l/min, 10 s, 29.0%; 20/69) and to i.v. administration of CCK (5 microg/kg, 24.5%; 11/45) when compared to phasic-type neurons. However, most non-phasic-type neurons that demonstrated excitation in response to i.v. administration of CCK (88.9%; 8/9) did not respond to air-jet stimulation. The present study indicated that phasically firing neurons recorded from the PVN in conscious, freely moving rats are putative vasopressin-secreting neurons on the basis of their responses to intero- and exteroceptive stressors. These data contribute to our understanding of local neural mechanisms within the PVN that are responsible for stress responses in conscious rats.

Enhanced cardiovascular alteration and Fos expression induced by central salt loading in a conscious rat transgenic for the metallothionein-vasopressin fusion gene.

The present study is an investigation of the responses of the cardiovascular system and Fos expression to intracerebroventricular (i.c.v.) administration of hypertonic saline (HS) in conscious arginine vasopressin (AVP)-overexpressing transgenic (Tg) and control rats. Central HS (0.3, 0.67, or 1.0M NaCl, 1 microl/min for 20 min) significantly increased the mean arterial blood pressure (MABP) and Fos-like immunoreactivity (FLI) in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus, the area postrema (AP), the median preoptic nucleus (MnPO), and the organum vasculosum laminae terminalis (OVLT) in both Tg and control rats. The changes in MABP and FLI were significantly larger in Tg rats than in control rats. i.c.v. pretreatment with the AVP V1 receptor antagonist, OPC-21268, blocked the increase in MABP and significantly decreased the Fos expression in the PVN (posterior magnocellular (pm) component) induced by 0.3 M HS in the Tg rats. The present study demonstrates an increased responsiveness to i.c.v. administration of HS in AVP Tg rats, suggesting the relationship between the vasopressinergic drive and central cardiovascular response via, at least in part, the V1 receptor in the PVN magnocellular neurons.

Possible involvement of nitric oxide in the central salt-loading-induced cardiovascular responses in conscious rats.

The objective of this study was to elucidate the possible involvement of nitric oxide (NO) in the cardiovascular responses induced by central salt loading. Direct perfusion of the hypothalamic paraventricular nucleus (PVN) region with hypertonic saline (0.3 or 0.45 M) was performed in conscious rats by using an in vivo brain microdialysis technique. The extracellular concentration of NO metabolites in the PVN region was measured, as were the blood pressure (BP) and heart rate (HR). Perfusion of 0.45 M saline increased the BP, HR, and NO metabolite levels in the PVN region; however, perfusion of 0.3 M saline enhanced only the level of NO metabolites but did not induce changes in the BP and HR. Next, we determined whether the NO was involved in the cardiovascular responses induced by hypertonic saline. Pretreatment with N(G)-methyl-L-arginine (L-NMMA), an inhibitor of NO synthase, attenuated the increases in the BP and HR induced by direct perfusion of 0.45 M saline, while direct infusion of 3-morpholinosyndnonimine (SIN-1, a NO donor) in the PVN region induced increases in the BP and HR. These results suggest that local perfusion of the PVN region with hypertonic saline elicits a local release of NO, which may be carried out by activating nitric oxide synthase to produce cardiovascular responses.

Enhanced effects of central angiotensin II on cardiovascular and drinking responses in inbred polydipsic (STR/N) mice

STR/N, an inbred strain of mice, is known to exhibit extreme polydipsia and polyuria. The objective of this study was to investigate the possible reasons for polydipsia. First, comparisons were made between STR/N mice and control mice from the Institute of Cancer Research (ICR) concerning daily drinking, urinary excretion, and basal cardiovascular function. Then, since angiotensin II (ANG II) is a potent stimulus for drinking behavior, we investigated the effects of intracerebroventricular (i.c.v.) administration of ANG II on cardiovascular and water intake responses. Daily water intake, food intake, urinary volume, and urinary electrolytes (Na and K) excretion were larger in STR/N mice than in ICR mice, and the basal blood pressure was significantly lower in STR/N mice than in ICR mice. The i.c.v. administration of ANG II (10 pmol/per mouse) resulted in increased mean arterial blood pressure (MAP) and water intake in both STR/N and ICR mice, but the changes in MAP were significantly larger in STR/N mice than in ICR mice. These results suggest that polydipsia in STR/N mice is at least partially attributable to high sensitivity of central ANG II receptors and low MAP.

Expression of N-terminally truncated isoforms of CDP/CUX is increased in human uterine leiomyomas

Genetic analyses and mRNA expression studies have implicated CUTL1 as a candidate tumor‐suppressor gene in uterine leiomyomas and breast cancers. However, modulation of CDP/Cux, the protein encoded by CUTL1, does not agree with this notion. The activity of CDP/Cux, which is the DNA binding subunit of HiNF‐D, was upregulated as normal cells progressed into S phase and constitutively elevated in several tumor cell lines. Activation of CDP/Cux at the G1/S transition involved the proteolytic processing of the protein to generate a shorter isoform. Uterine leiomyomas represent a unique reagent for molecular analysis because they are resected as homogenous tumor tissue together with the adjacent normal myometrium and they are often very large. In the present study, proteins were isolated from 16 pairs of matched tumors and adjacent myometrium and analyzed by Western blot and electrophoretic mobility shift assays. Strikingly, in 11/16 tumors, the steady‐state level of small CDP/Cux isoforms was increased compared to normal control tissue. Where tested, a corresponding increase in CDP/Cux stable DNA binding activity was observed. DNA sequencing analysis of CUTL1 cDNAs from 6 leiomyomas, including 4 with LOH of CUTL1, did not reveal any gross rearrangement or point mutations. Altogether these findings suggest that CUTL1 is probably not the tumor suppressor on 7q22. Moreover, the frequent increase in smaller CDP/Cux isoforms indicates that molecular events associated with the truncation of CDP/Cux proteins may be selected in uterine leiomyomas.