scholarly journals Resistance to Dopamine Agonists in Pituitary Tumors: Molecular Mechanisms

2022 ◽  
Vol 12 ◽  
Author(s):  
Claudia Pivonello ◽  
Roberta Patalano ◽  
Mariarosaria Negri ◽  
Rosa Pirchio ◽  
Annamaria Colao ◽  
...  
Keyword(s):  
Dopamine Agonists ◽  
Molecular Mechanisms ◽  
Signal Transduction Pathway ◽  
Pituitary Tumors ◽  
Benign Tumors ◽  
Membrane Expression ◽  
Secondary Resistance ◽  
First Line Therapy ◽  
Molecular Events ◽  
Predominant Type

Pituitary neuroendocrine tumors (PitNET) are commonly benign tumors accounting for 10-25% of intracranial tumors. Prolactin-secreting adenomas represent the most predominant type of all PitNET and for this subtype of tumors, the medical therapy relies on the use of dopamine agonists (DAs). DAs yield an excellent therapeutic response in reducing tumor size and hormonal secretion targeting the dopamine receptor type 2 (D2DR) whose higher expression in prolactin-secreting adenomas compared to other PitNET is now well established. Moreover, although DAs therapy does not represent the first-line therapy for other PitNET, off-label use of DAs is considered in PitNET expressing D2DR. Nevertheless, DAs primary or secondary resistance, occurring in a subset of patients, may involve several molecular mechanisms, presently not fully elucidated. Dopamine receptors (DRs) expression is a prerequisite for a proper DA function in PitNET and several molecular events may negatively modify DR membrane expression, through the DRs down-regulation and intracellular trafficking, and DR signal transduction pathway. The current mini-review will summarise the presently known molecular events that underpin the unsuccessful therapy with DAs.

New pituitary oncogenes.

2000 ◽  
pp. 3-15 ◽  
Author(s):  
A P Heaney ◽  
S Melmed
Keyword(s):  
Pituitary Tumor ◽  
Molecular Mechanisms ◽  
Cell Clone ◽  
Tumor Therapy ◽  
Pituitary Tumors ◽  
Molecular Probes ◽  
Molecular Events ◽  
Therapeutic Decisions ◽  
Pituitary Cell Clone ◽  
Considerable Morbidity

Pituitary tumors are common monoclonal neoplasms which cause considerable morbidity and mortality. Several molecular events underlying pituitary tumorigenesis have been elucidated in recent years, but no tumor marker has clearly emerged which assists clinical and therapeutic decisions. Activating mutations and loss of inactivating mutations, together with hypothalamic hormones, circulating hormones, growth factors and cytokines cooperatively ensure the inexorable expansion of the initial mutated pituitary cell clone. This review describes new developments in our understanding of the molecular mechanisms involved in the pathogenesis of pituitary tumors. The availability of molecular probes will allow the early prediction of tumor behavior, identify targets for designing subcellular pituitary tumor therapy and provide novel approaches to pituitary tumor management.

Molecular Basis and Clinical Aspects of Hereditary Megakaryocyte and Platelet Membrane Glycoprotein Disorders

1996 ◽  
Vol 16 (02) ◽  
pp. 114-138 ◽  
Author(s):  
R. E. Scharf
Keyword(s):  
Genetic Basis ◽  
Molecular Mechanisms ◽  
Molecular Genetic ◽  
Platelet Membrane ◽  
Clinical Aspects ◽  
Membrane Glycoprotein ◽  
Membrane Glycoproteins ◽  
Membrane Expression ◽  
Receptor Complexes ◽  
Platelet Membrane Glycoprotein

SummarySpecific membrane glycoproteins (GP) expressed by the megakaryocyte-platelet system, including GPIa-lla, GPIb-V-IX, GPIIb-llla, and GPIV are involved in mediat-ing platelet adhesion to the subendothelial matrix. Among these glycoproteins, GPIIb-llla plays a pivotal role since platelet aggregation is exclusively mediated by this receptor and its interaction with soluble macromolecular proteins. Inherited defects of the GPIIb-llla or GPIb-V-IX receptor complexes are associated with bleeding disorders, known as Glanzmann's thrombasthenia, Bernard-Soulier syndrome, or platelet-type von Willebrand's disease, respectively. Using immuno-chemical and molecular biology techniques, rapid advances in our understanding of the molecular genetic basis of these disorders have been made during the last few years. Moreover, analyses of patients with congenital platelet membrane glycoprotein abnormalities have provided valuable insights into molecular mechanisms that are required for structural and functional integrity, normal biosynthesis of the glycoprotein complexes and coordinated membrane expression of their constituents. The present article reviews the current state of knowledge of the major membrane glycoproteins in health and disease. The spectrum of clinical bleeding manifestations and established diagnostic criteria for each of these dis-orders are summarized. In particular, the variety of molecular defects that have been identified so far and their genetic basis will be discussed.

scholarly journals The Hormetic Effect of Metformin: “Less Is More”?

2021 ◽  
Vol 22 (12) ◽  
pp. 6297
Author(s):  
Isabella Panfoli ◽  
Alessandra Puddu ◽  
Nadia Bertola ◽  
Silvia Ravera ◽  
Davide Maggi
Keyword(s):  
Complex I ◽  
Molecular Mechanisms ◽  
Hepatic Glucose Production ◽  
Glucose Production ◽  
Target Tissue ◽  
Atp Production ◽  
Less Is More ◽  
First Line Therapy ◽  
Hormetic Effect ◽  
Intracellular Content

Metformin (MTF) is the first-line therapy for type 2 diabetes (T2DM). The euglycemic effect of MTF is due to the inhibition of hepatic glucose production. Literature reports that the principal molecular mechanism of MTF is the activation of 5′-AMP-activated protein kinase (AMPK) due to the decrement of ATP intracellular content consequent to the inhibition of Complex I, although this effect is obtained only at millimolar concentrations. Conversely, micromolar MTF seems to activate the mitochondrial electron transport chain, increasing ATP production and limiting oxidative stress. This evidence sustains the idea that MTF exerts a hormetic effect based on its concentration in the target tissue. Therefore, in this review we describe the effects of MTF on T2DM on the principal target organs, such as liver, gut, adipose tissue, endothelium, heart, and skeletal muscle. In particular, data indicate that all organs, except the gut, accumulate MTF in the micromolar range when administered in therapeutic doses, unmasking molecular mechanisms that do not depend on Complex I inhibition.

Molecular Correlates of Imatinib Resistance in Gastrointestinal Stromal Tumors

2006 ◽  
Vol 24 (29) ◽  
pp. 4764-4774 ◽  
Author(s):  
Michael C. Heinrich ◽  
Christopher L. Corless ◽  
Charles D. Blanke ◽  
George D. Demetri ◽  
Heikki Joensuu ◽  
...  
Keyword(s):  
Gastrointestinal Stromal Tumors ◽  
Molecular Mechanisms ◽  
Clonal Evolution ◽  
Clinical Problem ◽  
Primary Resistance ◽  
Imatinib Resistance ◽  
Secondary Resistance ◽  
Stromal Tumors ◽  
Rnai Technology ◽  
Imatinib Resistant

Purpose Gastrointestinal stromal tumors (GISTs) commonly harbor oncogenic mutations of the KIT or platelet-derived growth factor alpha (PDGFRA) kinases, which are targets for imatinib. In clinical studies, 75% to 90% of patients with advanced GISTs experience clinical benefit from imatinib. However, imatinib resistance is an increasing clinical problem. Patients and Methods One hundred forty-seven patients with advanced, unresectable GISTs were enrolled onto a randomized, phase II clinical study of imatinib. Specimens from pretreatment and/or imatinib-resistant tumors were analyzed to identify molecular correlates of imatinib resistance. Secondary kinase mutations of KIT or PDGFRA that were identified in imatinib-resistant GISTs were biochemically profiled for imatinib sensitivity. Results Molecular studies were performed using specimens from 10 patients with primary and 33 patients with secondary resistance. Imatinib-resistant tumors had levels of activated KIT that were similar to or greater than those typically found in untreated GISTs. Secondary kinase mutations were rare in GISTs with primary resistance but frequently found in GISTs with secondary resistance (10% v 67%; P = .002). Evidence for clonal evolution and/or polyclonal secondary kinase mutations was seen in three (18.8%) of 16 patients. Secondary kinase mutations were nonrandomly distributed and were associated with decreased imatinib sensitivity compared with typical KIT exon 11 mutations. Using RNAi technology, we demonstrated that imatinib-resistant GIST cells remain dependent on KIT kinase activity for activation of critical downstream signaling pathways. Conclusion Different molecular mechanisms are responsible for primary and secondary imatinib resistance in GISTs. These findings have implications for future approaches to the growing problem of imatinib resistance in patients with advanced GISTs.

scholarly journals Physical dissociation of the TCR-CD3 complex accompanies receptor ligation.

1995 ◽  
Vol 182 (6) ◽  
pp. 1997-2006 ◽  
Author(s):  
H Kishimoto ◽  
R T Kubo ◽  
H Yorifuji ◽  
T Nakayama ◽  
Y Asano ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Cell Surface ◽  
Molecular Mechanisms ◽  
Signal Transduction Pathway ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Protein Levels ◽  
Before And After ◽  
Physical Dissociation ◽  
Receptor Ligation

Recent studies indicate that there may be functional uncoupling of the TCR-CD3 complex and suggest that the TCR-CD3 complex is composed of two parallel signal-transducing units, one made of gamma delta epsilon chains and the other of zeta chains. To elucidate the molecular mechanisms that may explain the functional uncoupling of TCR and CD3, we have analyzed their expression by using flow cytometry as well as immunochemical means both before and after stimulation with anti-TCR-beta, anti-CD3 epsilon, anti-CD2, staphylococcal enterotoxin B, and ionomycin. We present evidence that TCR physically dissociates from CD3 after stimulation of the TCR-CD3 complex. Stimulation with anti-CD3 resulted in down-modulation of TCR within 45 min whereas CD3 epsilon was still expressed on the cell surface as detected by flow cytometry. However, the cell surface expression of TCR and CD3 was not affected when cells were stimulated with anti-TCR-beta under the same conditions. In the case of anti-CD3 treatment of T cells, the TCR down-modulation appeared to be due to the internalization of TCR, as determined by immunoelectron microscopy. Immunochemical analysis of cells after stimulation with either anti-TCR or anti-CD3 mAbs revealed that the overall protein levels of TCR and CD3 were similar. More interestingly, the dissociation of the TCR-CD3 complex was observed with both treatments and occurred in a manner that the TCR and the associated TCR-zeta chain dissociated as a unit from CD3. These results provide the first report of physical dissociation of TCR and CD3 after stimulation through the TCR-CD3 complex. The results also suggest that the signal transduction pathway triggered by TCR may differ from that induced by CD3.

Antiepileptic and Antidepressant Drugs Used in the Treatment of Pain

2017 ◽  
Author(s):  
Lucia Daiana Voiculescu
Keyword(s):  
Serotonin Syndrome ◽  
Molecular Mechanisms ◽  
Tricyclic Antidepressants ◽  
Antidepressant Drugs ◽  
First Line ◽  
Off Label ◽  
First Line Therapy ◽  
Line Therapy ◽  
Pain Pathways ◽  
Different Levels

Antiepileptics and antidepressants are two categories of drugs frequently used as adjuvant analgesics. They interfere with the pain pathways at different levels through complex and not always well-defined molecular mechanisms. Although only a few have been licensed for use in the treatment of certain types of pain, anticonvulsants and antidepressants are widely prescribed off-label for pain associated with a variety of conditions. Most solid data come from experience with their use for postherpetic neuralgia, pain associated with diabetic neuropathy, and fibromyalgia. Anticonvulsants and antidepressant drugs are frequently used as first-line therapy in the treatment of pain, especially neuropathic type. Key words: antidepressant drugs, antiepileptic drugs, carbamazepine, gabapentinoids, neuropathic pain, off-label use, serotonin-norepinephrine reuptake inhibitors, serotonin syndrome, tricyclic antidepressants, use in specific populations

scholarly journals Molecular Mechanisms Regulating Organ-Specific Metastases in Epithelial Ovarian Carcinoma

Cancers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 444 ◽  
Author(s):  
Maria Barbolina
Keyword(s):  
Ovarian Cancer ◽  
Clinical Trials ◽  
Ovarian Carcinoma ◽  
Molecular Mechanisms ◽  
Epithelial Ovarian Carcinoma ◽  
Gynecologic Malignancy ◽  
Peritoneal Adhesion ◽  
Metastatic Cascade ◽  
Predominant Type ◽  
Organ Specific

Epithelial ovarian carcinoma is the most predominant type of ovarian carcinoma, the deadliest gynecologic malignancy. It is typically diagnosed late when the cancer has already metastasized. Transcoelomic metastasis is the most predominant mechanism of dissemination from epithelial ovarian carcinoma, although both hematogenously and lymphogenously spread metastases also occur. In this review, we describe molecular mechanisms known to regulate organ-specific metastasis from epithelial ovarian carcinoma. We begin by discussing the sites colonized by metastatic ovarian carcinoma and rank them in the order of prevalence. Next, we review the mechanisms regulating the transcoelomic metastasis. Within this chapter, we specifically focus on the mechanisms that were demonstrated to regulate peritoneal adhesion—one of the first steps in the transcoelomic metastatic cascade. Furthermore, we describe mechanisms of the transcoelomic metastasis known to regulate colonization of specific sites within the peritoneal cavity, including the omentum. Mechanisms underlying hematogenous and lymphogenous metastatic spread are less comprehensively studied in ovarian cancer, and we summarize mechanisms that were identified to date. Lastly, we discuss the outcomes of the clinical trials that attempted to target some of the mechanisms described in this review.

scholarly journals Sunitinib resistance in renal cell carcinoma

2014 ◽  
Vol 1 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Christudas Morais
Keyword(s):  
Renal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Renal Cell ◽  
Molecular Mechanisms ◽  
Acquired Resistance ◽  
Progression Free Survival ◽  
Sequential Therapy ◽  
Intrinsic Resistance ◽  
First Line Therapy ◽  
The Many

Of the many targeted therapies introduced since 2006, sunitinib has carved its way to become the most commonly used first-line therapy for the treatment of metastatic renal cell carcinoma (RCC). Despite significant improvements in progression-free survival, 30% of the patients are intrinsically resistant to sunitinib and the remaining 70% who respond initially will eventually become resistant in 6–15 months. While the molecular mechanisms of acquired resistance to sunitinib have been unravelling at a rapid rate, the mechanisms of intrinsic resistance remain elusive. Combination therapy, sunitinib-rechallenge and sequential therapy have been investigated as means to overcome resistance to sunitinib. Of these, sequential therapy appears to be the most promising strategy. This mini review summarises our emerging understanding of the molecular mechanisms, and the strategies employed to overcome sunitinib resistance.

scholarly journals Epigenetic Effects Induced by Methamphetamine and Methamphetamine-Dependent Oxidative Stress

2018 ◽  
Vol 2018 ◽  
pp. 1-28 ◽  
Author(s):  
Fiona Limanaqi ◽  
Stefano Gambardella ◽  
Francesca Biagioni ◽  
Carla L. Busceti ◽  
Francesco Fornai
Keyword(s):  
Molecular Mechanisms ◽  
Neuropsychiatric Disorders ◽  
Behavioral Alterations ◽  
Neuronal Phenotype ◽  
Cellular Events ◽  
Epigenetic Effects ◽  
Molecular Events ◽  
Epigenetic Events ◽  
Genetic Modifications ◽  
Altered Gene

Methamphetamine is a widely abused drug, which possesses neurotoxic activity and powerful addictive effects. Understanding methamphetamine toxicity is key beyond the field of drug abuse since it allows getting an insight into the molecular mechanisms which operate in a variety of neuropsychiatric disorders. In fact, key alterations produced by methamphetamine involve dopamine neurotransmission in a way, which is reminiscent of spontaneous neurodegeneration and psychiatric schizophrenia. Thus, understanding the molecular mechanisms operated by methamphetamine represents a wide window to understand both the addicted brain and a variety of neuropsychiatric disorders. This overlapping, which is already present when looking at the molecular and cellular events promoted immediately after methamphetamine intake, becomes impressive when plastic changes induced in the brain of methamphetamine-addicted patients are considered. Thus, the present manuscript is an attempt to encompass all the molecular events starting at the presynaptic dopamine terminals to reach the nucleus of postsynaptic neurons to explain how specific neurotransmitters and signaling cascades produce persistent genetic modifications, which shift neuronal phenotype and induce behavioral alterations. A special emphasis is posed on disclosing those early and delayed molecular events, which translate an altered neurotransmitter function into epigenetic events, which are derived from the translation of postsynaptic noncanonical signaling into altered gene regulation. All epigenetic effects are considered in light of their persistent changes induced in the postsynaptic neurons including sensitization and desensitization, priming, and shift of neuronal phenotype.

scholarly journals Molecular Events Involved in Influenza A Virus-Induced Cell Death

2022 ◽  
Vol 12 ◽  
Author(s):  
Rui Gui ◽  
Quanjiao Chen
Keyword(s):  
Cell Death ◽  
Influenza A Virus ◽  
Influenza A ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Tissue Destruction ◽  
Inflammatory Reactions ◽  
Molecular Events ◽  
Host Death

Viral infection usually leads to cell death. Moderate cell death is a protective innate immune response. By contrast, excessive, uncontrolled cell death causes tissue destruction, cytokine storm, or even host death. Thus, the struggle between the host and virus determines whether the host survives. Influenza A virus (IAV) infection in humans can lead to unbridled hyper-inflammatory reactions and cause serious illnesses and even death. A full understanding of the molecular mechanisms and regulatory networks through which IAVs induce cell death could facilitate the development of more effective antiviral treatments. In this review, we discuss current progress in research on cell death induced by IAV infection and evaluate the role of cell death in IAV replication and disease prognosis.

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