Inhibition of Ubiquitin-specific Peptidase 8 Suppresses Adrenocorticotropic Hormone Production and Tumorous Corticotroph Cell Growth in AtT20 Cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Two recent whole-exome sequencing researches identifying somatic mutations in the ubiquitin-specific protease 8 (USP8) gene in pituitary corticotroph adenomas provide exciting advances in this field. These mutations drive increased epidermal growth factor receptor (EGFR) signaling and promote adrenocorticotropic hormone (ACTH) production. This study was to investigate whether the inhibition of USP8 activity could be a strategy for the treatment of Cushing's disease (CD).</p><p><b>METHODS</b>The anticancer effect of USP8 inhibitor was determined by testing cell viability, colony formation, apoptosis, and ACTH secretion. The immunoblotting and quantitative reverse transcription polymerase chain reaction were conducted to explore the signaling pathway by USP8 inhibition.</p><p><b>RESULTS</b>Inhibition of USP8-induced degradation of receptor tyrosine kinases including EGFR, EGFR-2 (ERBB2), and Met leading to a suppression of AtT20 cell growth and ACTH secretion. Moreover, treatment with USP8 inhibitor markedly induced AtT20 cells apoptosis.</p><p><b>CONCLUSIONS</b>Inhibition of USP8 activity could be an effective strategy for CD. It might provide a novel pharmacological approach for the treatment of CD.</p>

Neuropsychiatric disorders and cognitive dysfunction in patients with Cushing's disease / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>To review the main neuropsychiatric disorders and cognitive deficits in patients with Cushing's disease (CD) and the associated pathophysiological mechanisms underlying CD. These mechanistic details may provide recommendations for preventing or treating the cognitive impairments and mood disorders in patients with CD.</p><p><b>DATA SOURCES</b>Data were obtained from papers on psychiatric and cognitive complications in CD published in English within the last 20 years. To perform the PubMed literature search, the following keywords were input: cushing's disease, cognitive, hippocampal, or glucocorticoids.</p><p><b>STUDY SELECTION</b>Studies were selected if they contained data relevant to the topic addressed in the particular section. Because of the limited length of this article, we have frequently referenced recent reviews that contain a comprehensive amalgamation of literature rather than the actual source papers.</p><p><b>RESULTS</b>Patients with active CD not only suffer from many characteristic clinical features, but also show some neuropsychiatric disorders and cognitive impairments. Among the psychiatric manifestations, the common ones are emotional instability, depressive disorder, anxious symptoms, impulsivity, and cognitive impairment. Irreversible effects of previous glucocorticoid (GC) excess on the central nervous system, such as hippocampal and the basal ganglia, is the most reasonable reason. Excess secretion of cortisol brings much structural and functional changes in hippocampal, such as changes in neurogenesis and morphology, signaling pathway, gene expression, and glutamate accumulation. Hippocampal volume loss can be found in most patients with CD, and decreased glucose utilization caused by GCs may lead to brain atrophy, neurogenesis impairment, inhibition of long-term potentiation, and decreased neurotrophic factors; these may also explain the mechanisms of GC-induced brain atrophy and hippocampal changes.</p><p><b>CONCLUSIONS</b>Brain atrophy and hippocampal changes caused by excess secretion of cortisol are thought to play a significant pathophysiological role in the etiology of changes in cognitive function and psychiatric disturbances. The exact mechanisms by which GCs induce hippocampal volume loss are not very clear till now. So, further investigations into the mechanisms by which GCs affect the brain and the effective coping strategy are essential.</p>

Loss of heterozygosity on chromosome 22 in sporadic schwannoma and its relation to the proliferation of tumor cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Schwannoma is the tumor arising mainly from the cranial and spinal nerves. Bilateral vestibular schwannoma is the hallmark of neurofibromatosis type 2 (NF2). The NF2 gene has been cloned with comprehensive analysis of its mutations in schwannoma. However, most studies focused on vestibular schwannoma. There are differences in proliferation of tumor cell and ultrastructure between vestibular and spinal schwannomas. It is unknown whether genetic alterations in vestibular schwannoma are different from those in non-vestibular schwannoma. We analyzed the loss of heterozygosity (LOH) on chromosome 22 in patients with sporadic schwannoma including vestibular and spinal schwannomas and correlated this genetic alteration with tumor proliferation.</p><p><b>METHODS</b>In 54 unrelated patients without clinical NF1 or NF2, 36 patients had sporadic vestibular schwannoma, and 18 dorsal spinal root schwannoma. Four highly polymorphic linkage to NF2 gene microsatellite DNA markers (D22S264, D22S268, D22S280, CRYB2) were used to analyze LOH. The proliferative index was evaluated by Ki-67 and proliferative cell nuclear antigen (PCNA) immunostaining. Student's t test was used to analyze the difference of the proliferative index between schwannoma with LOH and that without LOH. The difference of the frequency of LOH in vestibular and spinal schwannomas was investigated by the chi-square test.</p><p><b>RESULTS</b>Twenty-three schwannomas (42.6%, 23/54) showed allele loss. The frequency of LOH in vestibular schwannoma was significantly higher than that in spinal schwannoma (chi2 = 5.14, P < 0.05). The proliferative index of schwannoma with LOH was significantly higher than that without LOH (tki-67 = 2.97, P = 0.0045; tPCNA = 2.93, P = 0.0051).</p><p><b>CONCLUSIONS</b>LOH on chromosome 22 is a frequent event in the tumorigenesis of sporadic schwannoma. And, there is a correlation between LOH on chromosome 22 and proliferative activity in schwannoma. The frequency of LOH in vestibular schwannoma is significantly different from that in spinal schwannoma.</p>