Association of Triiodothyronine Levels With Prostate Cancer Histopathological Differentiation and Tumor Stage.

BACKGROUND/AIM: The aim of this study was to determine the association between total triiodothyronine (T3), free fraction of thyroxin (FT4), and thyrotropin (TSH) levels with prostate cancer histopathological features. PATIENTS AND METHODS: Blood samples from 140 patients with prostate cancer were analyzed preoperatively and stratified according to postoperative histopathological differentiation. The first group (N=62) included patients with prostate cancer Grade Groups (GG) 1-2, while the second group (N=63) included patients with prostate cancer GG 3-5. RESULTS: T3 levels were significantly higher in patients with prostate cancer GG 3-5 (p=0.047). There was no significant difference in the FT4 and TSH levels between the two groups (p=0.680 and 0.801, respectively). T3 levels were positively correlated with tumor percentage involvement (TPI) (p=0.002), and pT stage (p=0.047) on definitive pathology. CONCLUSION: Higher T3 levels are associated with several indicators of prostate cancer histopathological aggressiveness.

The Appearance of 4-Hydroxy-2-Nonenal (HNE) in Squamous Cell Carcinoma of the Oropharynx.

Tumor growth is associated with oxidative stress, which causes lipid peroxidation. The most intensively studied product of lipid peroxidation is 4-hydroxy-2-nonenal (HNE), which is considered as a "second messenger of free radicals" that binds to proteins and acts as a growth-regulating signaling factor. The incidence of squamous cell carcinoma of the oropharynx is associated with smoking, alcohol and infection of human papilloma virus (HPV), with increasing incidence world-wide. The aim of this retrospective study involving 102 patients was to determine the immunohistochemical appearance of HNE-protein adducts as a potential biomarker of lipid peroxidation in squamous cell carcinoma of the oropharynx. The HNE-protein adducts were detected in almost all tumor samples and in the surrounding non-tumorous tissue, while we found that HNE is differentially distributed in squamous cell carcinomas in dependence of clinical stage and histological grading of these tumors. Namely, the level of HNE-immunopositivity was increased in comparison to the normal oropharyngeal epithelium in well- and in moderately-differentiated squamous cell carcinoma, while it was decreasing in poorly differentiated carcinomas and in advanced stages of cancer. However, more malignant and advanced cancer was associated with the increase of HNE in surrounding, normal tissue. This study confirmed the onset of lipid peroxidation, generating HNE-protein adducts that can be used as a valuable bioactive marker of carcinogenesis in squamous cell carcinoma of the oropharynx, as well as indicating involvement of HNE in pathophysiological changes of the non-malignant tissue in the vicinity of cancer.

Breast Cancer Molecular Subtypes and Oxidative DNA Damage.

BACKGROUND: Oxidative stress is thought to play a major role in etiology of many cancers, including breast cancer. 8-hydroxy-2'deoxyguanosine (8-OHdG) is the most abundant marker of oxidative DNA damage. The aim of this study was to assess the extent of oxidative DNA damage in different breast cancer molecular surrogate subtypes to investigate the prognostic relevance and role of oxidative base lesion (8-OHdG) in the etiology of breast cancer. MATERIALS AND METHODS: 8-OHdG expression was immunohistochemicaly studied on tissue microarrays constructed from 152 patients with invasive breast cancer. Expression was correlated with other prognostic factors, as well as different breast cancer molecular surrogate subtypes such as luminal A, luminal B [human epidermal growth factor receptor 2 (HER2) negative], luminal B (HER2 positive), HER2-enriched ad triple-negative tumors. RESULTS: Triple-negative breast carcinomas (TNBCs) were more frequently 8-OHdG negative compared with non-TNBCs (P=0.036). There was no statistically significant difference between 8-OHdG expression and other breast cancer molecular subtypes.In univariate analysis, there was no significant difference between 8-OHdG expression and breast cancer-specific death, although in multivariate analysis 8-OHdG overexpression was associated with better breast cancer-specific survival (BCSS) (odds ratio=0.04, 95% confidence interval, 0.002-0.62). In Cox regression analysis, patients with moderate and strong 8-OHdG expression had 0.9 times smaller breast cancer death hazard ratio than patients with negative 8-OHdG expression. CONCLUSIONS: Oxidative stress may have less impact in the pathogenesis of TNBCs compared with other surrogate breast cancer molecular subtypes. 8-OHdG may be a promising biomarker in the prediction of prognosis for breast cancer patients.

Antiangiogenic effect of inhibitors of cytochrome P450 on rats with glioblastoma multiforme.

Cytochrome P450 epoxygenase catalyzes 5,6-, 8,9-, 11,12-, and 14,15-epoxyeicosatrienoic acids (EETs) from arachidonic acid (AA). In 1996, our group identified the expression of the cytochrome P450 2C11 epoxygenase (CYP epoxygenase) gene in astrocytes. Because of our finding an array of physiological functions have been attributed to EETs in the brain, one of the actions of EETs involves a predominant role in brain angiogenesis. Blockade of EETs formation with different epoxygenase inhibitors decreases endothelial tube formation in cocultures of astrocytes and capillary endothelial cells. The intent of this investigation was to determine if pharmacologic inhibition of formation of EETs is effective in reducing capillary formation in glioblastoma multiforme with a concomitant reduction in tumor volume and increase in animal survival time. Two mechanistically different inhibitors of CYP epoxygenase, 17-octadecynoic acid (17-ODYA) and miconazole, significantly reduced capillary formation and tumor size in glial tumors formed by injection of rat glioma 2 (RG2) cells, also resulting in an increased animal survival time. However, we observed that 17-ODYA and miconazole did not inhibit the formation of EETs in tumor tissue. This implies that 17-ODYA and miconazole appear to exert their antitumorogenic function by a different mechanism that needs to be explored.

Role of astrocytes in matching blood flow to neuronal activity.

The brain is critically dependent on oxygen and glucose supply for normal function. Various neurovascular control mechanisms assure that the blood supply of the brain is adequate to meet the energy needs of its components. Emerging evidence shows that neuronal activity can control microcirculation using astrocytes as a mediator. Astrocytes can sense neuronal activity and are involved in signal transmission. Synaptic activity triggers an increase in the intracellular calcium concentration [Ca(2+)]i of adjacent astrocytes, stimulating the release of adenosine triphosphate (ATP) and glutamate. The released ATP mediates the propagation of Ca(2+) waves between neighboring astrocytes, thereby recruiting them to mediate adequate cerebrovascular response to neuronal activation. Simultaneously, sodium-dependent glutamate uptake in astrocytes generates Na(+) waves and subsequently increases glucose uptake and metabolism that leads to the formation of lactate, which is then delivered to neurons as an energy substrate. Further, astrocytic Ca(2+) elevations can lead to secretion of vasodilatory substances from perivascular endfeet, such as epoxyeicosatrienoic acid (EETs), adenosine, nitric oxide (NO), and cyclooxygenase-2 (COX-2) metabolites, resulting in increased local blood flow. Thus, astrocytes by releasing vasoactive molecules mediate the neuron-astrocyte-endothelial signaling pathway and play a profound role in coupling blood flow to neuronal activity.

Isoflurane depresses the response of inspiratory hypoglossal motoneurons to serotonin in vivo.

BACKGROUND: Endogenous serotonin (5-HT) provides important excitatory drive to inspiratory hypoglossal motoneurons (IHMNs). In vitro studies show that activation of postsynaptic 5-HT receptors decreases a leak K+ channel conductance and depolarizes hypoglossal motoneurons (HMNs). In contrast, volatile anesthetics increase this leak K+ channel conductance, which causes neuronal membrane hyperpolarization and depresses HMN excitability. Clinical studies show upper airway obstruction, indicating HMN depression, even at subanesthetic concentrations. The authors hypothesized that if anesthetic activation of leak K+ channels caused neuronal depression in vivo, this effect could be antagonized with serotonin. In this case, the neuronal response to picoejected serotonin would be greater during isoflurane than with no isoflurane. METHODS: Studies were performed in decerebrate, vagotomized, paralyzed, and mechanically ventilated dogs during hypercapnic hyperoxia. The authors studied the effect of approximately 0.3 minimum alveolar concentration (MAC) isoflurane on the spontaneous discharge frequency patterns of single IHMNs and on the neuronal response to picoejection of 5-HT. RESULTS: Normalized data (mean +/- SD, n = 19) confirmed that 0.3 +/- 0.1 MAC isoflurane markedly reduced the spontaneous peak discharge frequency by 48 +/- 19% (P < 0.001) and depressed the slope of the spontaneous discharge patterns. The increase in neuronal frequency in response to 5-HT was reduced by 34 +/- 22% by isoflurane (P < 0.001). CONCLUSION: Subanesthetic concentrations of isoflurane strongly depressed canine IHMNs in vivo. The neuronal response to 5-HT was also depressed by isoflurane, suggesting that anesthetic activation of leak K+ channels, which is expected to result in a larger 5-HT response, was not a dominant mechanism in this depression.

Retrograde labeling reveals extensive distribution of genioglossal motoneurons possessing 5-HT2A receptors throughout the hypoglossal nucleus of adult dogs.

Inspiratory hypoglossal motoneurons (IHMNs) innervate the muscles of the tongue and play an important role in maintaining upper airway patency. However, this may be reduced during sleep and by sedatives, potent analgesics, and volatile anesthetics. The genioglossal (GG) muscle is the main protruder and depressor muscle of the tongue and contributes to upper airway patency during inspiration. In vitro data suggest that serotonin (5-hydroxytryptamine, 5-HT), via the 5-HT(2A) receptor (5-HT(2A)R) subtype, plays a key role in controlling the excitability of IHMNs. The distribution of GG motoneurons (GGMNs) within the hypoglossal (XII) nucleus has not been studied in the adult dog. Further, it is uncertain whether the 5-HT(2A)R is located on GGMNs in the adult dog. We therefore used the cholera toxin B (CTB) subunit as a retrograde tracer to map the location of GGMNs in combination with immunofluorescent labeling to determine the presence and colocalization of 5-HT(2A)R within the XII nucleus in adult mongrel dogs. Injection of CTB into the GG muscle resulted in retrogradely labeled cells in a compact column throughout the XII nucleus, extending from 0.75 mm caudal to 3.45 mm rostral to the obex. Fluorescence immunohistochemistry revealed extensive 5-HT(2A)R labeling on CTB-labeled GGMNs. Identification of the 5-HT(2A)R on GGMNs in the XII nucleus of the adult dog supports in vitro data and suggests a physiological role for this receptor subtype in controlling the excitability of GGMNs, which contribute to the maintenance of upper airway patency.

Serotonergic modulation of inspiratory hypoglossal motoneurons in decerebrate dogs.

Inspiratory hypoglossal motoneurons (IHMNs) maintain upper airway patency. However, this may be compromised during sleep and by sedatives, potent analgesics, and volatile anesthetics by either depression of excitatory or enhancement of inhibitory inputs. In vitro data suggest that serotonin (5-HT), through the 5-HT2A receptor subtype, plays a key role in controlling the excitability of IHMNs. We hypothesized that in vivo 5-HT modulates IHMNs activity through the 5-HT2A receptor subtype. To test this hypothesis, we used multibarrel micropipettes for extracellular single neuron recording and pressure picoejection of 5-HT or ketanserin, a selective 5-HT2A receptor subtype antagonist, onto single IHMNs in decerebrate, vagotomized, paralyzed, and mechanically ventilated dogs. Drug-induced changes in neuronal discharge frequency (F(n)) and neuronal discharge pattern were analyzed using cycle-triggered histograms. 5-HT increased the control peak F(n) to 256% and the time-averaged F(n) to 340%. 5-HT increased the gain of the discharge pattern by 61% and the offset by 34 Hz. Ketanserin reduced the control peak F(n) by 68%, the time-averaged F(n) by 80%, and the gain by 63%. These results confirm our hypothesis that in vivo 5-HT is a potent modulator of IHMN activity through the 5-HT2A receptor subtype. Application of exogenous 5-HT shows that this mechanism is not saturated during hypercapnic hyperoxia. The two different mechanisms, gain modulation and offset change, indicate that 5-HT affects the excitability as well as the excitation of IHMNs in vivo.