Overexpression of DNA (Cytosine-5)-Methyltransferase 1 (DNMT1) And DNA (Cytosine-5)-Methyltransferase 3A (DNMT3A) Is Associated with Aggressive Behavior and Hypermethylation of Tumor Suppressor Genes in Human Pituitary Adenomas.

BACKGROUND Alteration of DNA methylation of tumor suppressor genes (TSGs) is one of the most consistent epigenetic changes in human cancers. DNMTs play several important roles in DNA methylation and development of cancers. Regarding DNMTs protein expressions, little is known about the clinical significance and correlation with promoter methylation status of TSGs in human pituitary adenomas. MATERIAL AND METHODS We analyzed the protein expression of 3 DNMTs using immunohistochemistry and assessed DNA hypermethylation of RASSF1A, CDH13, CDH1, and CDKN2A (p16) in 63 pituitary adenomas. We examined associations between DNMTs expression and clinicopathological features or promoter methylation status of TSGs. RESULTS Overexpression of DNMTs was detected in pituitary adenomas. Frequencies of DNMT1 overexpression were significantly higher in macroadenomas, invasive tumors, and grade III and IV tumors. DNMT3A was frequently detected in invasive tumors and grade IV tumors. In addition, DNMT1 and DNMT3A were frequently detected in high-methylation tumors. Furthermore, in multivariate logistic regression, the significant association between DNMT1 or DNMT3A and high-methylation status persisted after adjusting for clinicopathological features. CONCLUSIONS Our findings suggested that tumor overexpression of DNMT1 and DNMT3A is associated with tumor aggressive behavior and high-methylation status in pituitary adenomas. Our data support a possible role of DNMT1 and DNMT3A in TSG promoter methylation leading to pituitary adenoma invasion and suggest that inhibition of DNMTs has the potential to become a new therapeutic approach for invasive pituitary adenoma.

MicroRNAs in Human Pituitary Adenomas.

MicroRNAs (miRNAs) are a class of recently identified noncoding RNAs that regulate gene expression at posttranscriptional level. Due to the large number of genes regulated by miRNAs, miRNAs play important roles in many cellular processes. Emerging evidence indicates that miRNAs are dysregulated in pituitary adenomas, a class of intracranial neoplasms which account for 10-15% of diagnosed brain tumors. Deregulated miRNAs and their targets contribute to pituitary adenomas progression and are associated with cell cycle control, apoptosis, invasion, and pharmacological treatment of pituitary adenomas. To provide an overview of miRNAs dysregulation and functions of these miRNAs in pituitary adenoma progression, we summarize the deregulated miRNAs and their targets to shed more light on their potential as therapeutic targets and novel biomarkers.

Sudden death of an infant with coronary involvement due to Takayasu arteritis.

We present an unusual case of sudden death of an 8-month-old female infant with coronary involvement due to Takayasu arteritis. She had been thought to be healthy, but died after presenting to a hospital with complains of vomiting. At autopsy, the aorta and its main branches were thickened and stenotic, with the abdominal aorta below the level of the orifice of renal arteries most severely affected. The ascending aorta was thickened and showed ostial stenosis in the coronary arteries bilaterally. The proximal segment of the left and right coronary arteries showed approximately 60% and over 90% occlusion, respectively. Microscopically, the intima was thickened due to an increase of intimal cells and fibers, and the adventitia showed thickening with fibrosis. In addition, remarkable infiltration of inflammatory cells, including multinuclear giant cells phagocytosing fragmented elastic fibers, and destruction of elastic fibers were observed in the media. We diagnosed the cause of death as coronary insufficiency induced by coronary involvement due to Takayasu arteritis. Takayasu arteritis was not considered as a cause of sudden infant death, although this disease can affect the coronary artery. This report suggests that Takayasu arteritis can be a life-threatening condition even in infants.

The effects of low-dose methamphetamine pretreatment on endoplasmic reticulum stress and methamphetamine neurotoxicity in the rat midbrain.

Methamphetamine (METH) neurotoxicity is involved in METH-related deaths. It has been suggested that the midbrain, together with the striatum, is affected by METH neurotoxicity and the endoplasmic reticulum (ER) stress is induced in the processes of METH neurotoxicity. In this study, we examined the effects of low-dose METH administration for 5d on GRP78 and C/EBP homologous protein (CHOP), both of which are induced under ER stress, and METH neurotoxicity in the rat midbrain. We showed that 1mg/kg of METH induced an increase in GRP78 protein and mRNA expression 1d after the last injection, but had no effect on the levels of CHOP, tyrosine hydroxylase (TH), or GFAP. Secondly, we evaluated the induction of ER stress and the extent of METH neurotoxicity in the midbrain of animals pretreated with METH. In animals pretreated with saline, we observed elevated CHOP levels, together with decreased TH levels and increased GFAP levels, indicative of METH neurotoxicity, after neurotoxic METH administration, while there was no significant change in GRP78 levels. In contrast, low-dose METH (1.0mg/kg) pretreatment increased GRP78 levels and inhibited the induction of CHOP in the midbrain without METH neurotoxicity. These findings of ER stress in animals pretreated with METH were associated with an early increase in SOD1 levels and upregulation of Bcl-2. Therefore, our study suggests that pretreatment with low-dose METH may be protective against METH neurotoxicity in the midbrain, leading to the suppression of oxidative stress and apoptotic mechanisms, in part via ER stress-related pathways. Because chronic human METH abusers administrate low-dose METH repeatedly over an extended period before lethal injection, investigation of the pathophysiology of METH neurotoxicity in animals pretreated with low-dose METH might provide useful information on the pathophysiology of chronic and/or lethal METH use in cases of METH-related deaths.

Renal immunohistochemical investigation for the differentiation of the cause of multiple trauma fatalities.

In fatalities with multiple traumatic injuries, it is important to determine the severity of trauma, the main damaged organ, and the antemortem pathophysiological condition. We examined 63 cases within 48 h of the postmortem interval, which included assaults, slips and falls and falls from heights, traffic accidents, and sharp instrumental injuries. Immunohistochemically, each kidney was stained against hemoglobin (Hb), myoglobin (Mb), superoxide dismutase (SOD), 8-hydroxy-2'-deoxyguanosine (8-OHdG), 150 kDa oxygen regulated protein (ORP150), pulmonary surfactant A (SP-A), and liver-type fatty acid binding protein (L-FABP). Bleeding or circulatory failure induced ORP150, 8-OHdG, and L-FABP in the kidney. Statistical analysis of the immunoreactivity revealed that in battered and/or abused cases, Hb could be considered a specific marker. Hb and Mb were observed in the cases with general severe trauma, such as slips and falls and falls from heights. In traffic accidents, ORP150 could reflect general circulatory failure with bleeding. SP-A was observed in the cases with severe thoracic injuries, such as lung injuries and multiple thoracic fractures. L-FABP appeared in cases with renal circulatory failure as well as renal injury. These findings suggest that immunohistochemical observation of the kidneys could be a useful tool in determining several key factors, such as the severity of injury, the specific damaged organ, and the pathological condition after injury.

Increased expression of HMGA1 correlates with tumour invasiveness and proliferation in human pituitary adenomas.

AIMS: High-mobility group A1 (HMGA1) is highly expressed in various benign and malignant tumours. The development of pituitary adenoma in Hmga1 transgenic mice has been reported. However, no studies have investigated HMGA1 expression and its clinical significance in human pituitary adenomas. METHODS AND RESULTS: Immunohistochemical expression of HMGA1 was analysed with respect to various clinicopathological factors in 95 pituitary adenomas. Nuclear expression of HMGA1 was observed in 62% of pituitary adenomas, whereas normal adenohypophysial tissues were negative. Although HMGA1 expression was frequently detected in clinically non-functioning adenomas - 90% of silent adrenocorticotropic hormone (ACTH), 76.2% of follicle-stimulating hormone/luteinizing hormone and 100% of null cell adenomas - it was also detected in 48.1% of growth hormone (GH), 60% of mixed GH/prolactin (PRL), 62.5% of PRL, 66.6% of thyroid-stimulating hormone and 37.5% of ACTH adenomas. HMGA1 expression was significantly higher in invasive adenomas or macroadenomas than in non-invasive adenomas or microadenomas (invasive versus non-invasive, P < 0.05; macroadenoma versus microadenoma, P < 0.05). In addition, HMGA1 showed the highest level in grade IV, more aggressive pituitary adenomas, than in grades I, II and III (IV versus I, P = 0.01; IV versus II, P = 0.01; IV versus III, P = 0.07). Furthermore, a significant correlation between HMGA1 expression and MIB-1 labelling index was observed (R = 0.368, P < 0.0002). CONCLUSIONS: These findings suggest that HMGA1 up-regulation has an important oncogenic role in pituitary tumorigenesis, as well as being a novel molecular marker of tumour proliferation and invasiveness.

DNA methyltransferases 1, 3a, and 3b overexpression and clinical significance in gastroenteropancreatic neuroendocrine tumors.

The alteration of DNA methylation is one of the most common epigenetic changes in human cancers. Three genes, namely, DNA methyltransferase 1, 3a, and 3b, which code for DNA methyltransferases that affect promoter methylation status, are thought to play an important role in the development of cancers and may be good anticancer therapy targets. The methylation of tumor suppressor genes has been reported in gastroenteropancreatic neuroendocrine tumors; however, there have been no studies about DNA methyltransferase protein expression and its clinical significance in gastroenteropancreatic neuroendocrine tumors. In this study, the expression of DNA methyltransferase 1, 3a, and 3b was studied in 63 gastroenteropancreatic neuroendocrine tumors by immunohistochemistry. The expression of DNA methyltransferase 1, 3a, and 3b was frequently detected in gastroenteropancreatic neuroendocrine tumors (87%, 81%, and 75%, respectively). The DNA methyltransferase 3a expression level was significantly higher in poorly differentiated neuroendocrine carcinomas than in well-differentiated neuroendocrine tumors or well-differentiated neuroendocrine carcinomas (P < .01 and P < .05, respectively). The expression of DNA methyltransferase 1, 3a, and 3b showed significantly higher levels in stage IV tumors than in stage I or II tumors. In addition, the expression levels of DNA methyltransferase 1, 3a, and 3b were positively correlated with the MIB-1 labeling index in gastroenteropancreatic neuroendocrine tumors (R = 0.293, P = .019; R = 0.457, P = .001; and R = 0.249, P = .049; respectively). In addition, the expression levels and positive immunostaining frequencies of DNA methyltransferase 3a and 3b were significantly lower in midgut neuroendocrine tumors than in foregut or hindgut neuroendocrine tumors. Our findings suggest that the overexpression of DNA methyltransferase 1, 3a, and 3b is related to tumorigenesis and the progression of gastroenteropancreatic neuroendocrine tumors.

Pituitary adenomas that show a faint GH-immunoreactivity but lack fibrous body: Pit-1 adenoma with endocrinologically low activity.

Growth hormone (GH)-producing pituitary adenomas have been classified into densely and sparsely granulated adenomas. The latter are chromophobic with weak GH-positivity and characteristically possess fibrous body (FB), aggregation of cytokeratin filaments. We report eight cases of unusual chromophobic adenomas. GH-immunoreactivity was detected in most adenoma cells in five cases and scattered in three cases. However, it appeared much weaker than that seen in ordinary GH-producing adenomas because of spotty immunoreactivity. Although intracytoplasmic organelles were well-developed, secretory granules were small and sparse. FB was not identified in any cases. Thyroid-stimulating hormone was positive in four cases. Pit-1 protein was positive in all eight cases. A weak labeling with GH probe was detected in two of two cases examined by in situ hybridization. Acromegalic features were evident in four cases, while mild or absent in four cases. GH levels were below 5 microg/l in four cases and 5-10 microg/l in the remaining cases. Macroadenomas and invasive adenomas were seen in seven and six cases, respectively.Pituitary adenomas that show a faint GH-immunoreactivity but lack FB do not fit the established classification. These adenomas may be a distinct pituitary adenoma type of Pit-1 lineage with endocrinologically low activity.

Microglial and astrocytic changes in the striatum of methamphetamine abusers.

Little is known about the role of glial cells in the striatum of chronic methamphetamine (METH) users. In this study, we immunohistochemically examined glial reactions in the striatum of chronic METH users who did not abstain from METH use and died of drug intoxication. Human glucose transporter 5 (hGLUT), a useful marker of microglia, and CR3.43, a major histocompatibility complex class II antigen specific for reactive microglia, were immunostained. Glial fibrillary acidic protein (GFAP) and S100 Beta were used for astrocyte immunohistochemistry. We analyzed 12 chronic METH users and 13 control subjects, and detected a 200-240% increase in the number of hGLUT5-positive cells in chronic METH users (p<0.01). However, we did not detect any proliferation of CR3.43-positive cells. The number of GFAP-positive astrocytes increased, but this increase was not significant (p>0.05). Moreover, S100B-positive cell density between the two groups was not significant (p>0.05). This study demonstrates the absence of reactive gliosis in the striatum of chronic METH users who did not abstain for prolonged periods from METH use. The results suggest that chronic METH use by itself did not activate glial cells in humans and reactive gliosis may not be involved in the mechanism underlying the loss of control in drug intake, which is a characteristic feature of drug addiction.

Clinicopathological characterization of TSH-producing adenomas: special reference to TSH-immunoreactive but clinically non-functioning adenomas.

Thyrotropin (thyroid-stimulating hormone (TSH))-producing pituitary adenomas have been known to be quite variable in clinical features covering from typical functioning TSH-producing adenomas (FTSHomas) associated with hyperthyroidism to clinically silent TSH cell adenomas (STAs) that are apparently unassociated with hyperthyroidism. It is important to distinguish STAs from other types of clinically non-functioning adenomas for adequate postoperative managements. However, because of rareness of TSH-producing adenomas, their histopathological features linking to the clinical manifestations have not been well characterized. Herein, we investigated clinical and histopathological findings to characterize 29 TSH-producing adenomas including 20 FTSHomas and nine STAs. Clinical symptoms of the patients with STAs included headache, visual defect, vertigo, and nausea. All STAs and 19 FTSHomas were macroadenoma. The average tumor size of STAs was significantly larger than that of FTSHomas (P < 0.05). The invasiveness was detected in 33% STAs and in 20% FTSHomas. Both STAs and FTSHomas showed a variety of morphological features and immunohistochemical profiles. Chromophobic polygonal or short-spindled tumor cells usually proliferated in a diffuse pattern, while they exhibited globoid or whorl-like appearance with intertwined cytoplasmic processes in both subgroups. Stromal fibrosis and calcification were often noted. Their nuclei were somehow pleomorphic. Ultrastructural features of all four STAs examined were similar to those of normal thyrotrophs. Thus, STAs and FTSHomas were indistinguishable by histology alone. Immunohistochemically, the number of TSH-positive cells in individual FTSHomas was highly various. Six tumors showed only a few TSH-positive cells (1-5%), and three were negative for TSH by conventional method without antigen retrieval. After proteinase K treatment, these tumors turned out TSH positive. As defined, STAs were TSH positive in more than 20% of tumor cells and three of them in more than 50%. Growth hormone- and/or prolactin-positive cells were detected in 55% STAs and 63% FTSHomas. Both pituitary-specific transcription factor 1 and GATA-binding protein 2 were expressed in all STAs and 20 FTSHomas. Membranous somatostatin receptor (SSTR)-2A immunoreactivity was found in 89% STAs and 94% FTSHomas, whereas SSTR5 was positive in 78% of both STAs and FTSHomas. MIB-1 labeling index was related to tumor invasiveness and tumor size (P < 0.05, P = 0.09, respectively). Thus, although both STAs and FTSHomas showed unique histopathological features distinct from other type adenomas, these two subgroups were indistinguishable by histopathology. Immunohistochemistry for TSH by use of antigen retrieval, transcription factors, and SSTRs may be useful to confirm STAs and to determine the postoperative therapy among various kinds of clinically non-functioning adenomas.

Overexpression of HMGA2 relates to reduction of the let-7 and its relationship to clinicopathological features in pituitary adenomas.

High-mobility group A2 is highly expressed during embryogenesis and in various benign and malignant tumors. Recent studies report that high-mobility group A2 is negatively regulated by the let-7 microRNAs (miRNAs) family in vitro. The development of pituitary adenomas in high-mobility group A2 transgenic mice showed that high-mobility group A2 may be involved in pituitary tumorigenesis. However, no studies have investigated the clinical significance of high-mobility group A2 and its relationship to the let-7 miRNA family in human pituitary adenomas. Using immunohistochemistry, we analyzed high-mobility group A2 expression with respect to various clinicopathologic factors in 98 pituitary adenomas. Overexpression of high-mobility group A2 was observed in 39% (38/98) of pituitary adenomas compared with normal adenohypophysial tissue and was frequently found in adenomas including prolactin (PRL), adrenocorticotrophic hormone, or follicle-stimulating hormone/luteinizing hormone and in null cell adenomas, but relatively rare in growth hormone (GH) and mixed GH/PRL adenomas. High-mobility group A2 expression was significantly associated with tumor invasion (P<0.05) and was significantly higher in grade IV than in grades I, II, and III adenomas (P<0.05). High levels of high-mobility group A2 expression were more frequently observed in macroadenomas than in microadenomas (P<0.05). High levels of high-mobility group A2 expression also significantly correlated with the proliferation marker Ki-67 (P<0.0001). Real-time quantitative RT-PCR analysis was carried out to evaluate the expression of let-7 in 55 pituitary adenomas. Subsequently, decreased expression of let-7 was confirmed in 23 of 55 (42%) adenomas and was correlated with high-grade tumors (P<0.05). An inverse correlation between let-7 and high-mobility group A2 expression was evident (R=-0.33, P<0.05). These findings support a causal link between let-7 and high-mobility group A2 whereby loss of let-7 expression induces high-mobility group A2 upregulation that represents an important mechanism in pituitary tumorigenesis and progression.