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Glioblastoma remains an incurable tumour (median survival: ~ 15 months) and little clinical progress has been made over the past decades. Therefore, identification of novel biomarkers and therapeutic targets is imperative. Targeting the somatostatin/cortistatin-system is considered a successful avenue for treating different tumour pathologies. Thus, we comprehensively characterized (clinically and molecularly) the expression of the somatostatin/cortistatin-system components [ligands and receptors (SSTRs)] using five cohorts of patients and tested the in-vitro therapeutic response of different SSTR-agonists and somatostatin analogs (SSAs) in primary patient-derived glioblastoma cells. A clear downregulation of the whole somatostatin/cortistatin-system (except for SSTR5) in glioblastoma vs . non-tumour brain samples was demonstrated, with high discriminatory capacity. Moreover, poor overall-survival and critical aggressiveness-parameters ( i.e., recurrence, IDH1 -wildtype and G-CIMP status, classical and mesenchymal GBM-subtypes, EGFR -amplification) were robustly associated with SSTR1/SSTR2 downregulation. Notably, octreotide, pasireotide, and SSTR1/2/5-agonists treatments significantly reduced cell-proliferation in primary patient-derived GBM-cells. Molecularly, antitumour effects of octreotide/pasireotide were exerted through key signalling-factors related to glioblastoma-aggressiveness ( i.e., CDKN1A-B/JAK-STAT/NF-κB/TGF-β-pathways). Altogether, this study demonstrated that somatostatin/cortistatin-system is drastically altered in GBM representing a useful prognostic tool, and that SSTR-modulators might represent a potential therapeutic strategy to treat specific subsets of patients with GBM.

Targeting neuroendocrine tumors expressing somatostatin receptor subtypes (sst) with radiolabeled somatostatin agonists is an established diagnostic and therapeutic approach in oncology. While agonists readily internalize into tumor cells, permitting accumulation of radioactivity, radiolabeled antagonists do not, and they have not been considered for tumor targeting. The macrocyclic chelator 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) was coupled to two potent somatostatin receptor-selective peptide antagonists [NH₂-CO-c(DCys-Phe-Tyr-DAgI⁸(Me,2-naphthoyl)-Lys-ThrPhe-Cys)-OH (sst₃-ODN-8) and a sst₂-selective antagonist (sst₂-ANT)], for labeling with$^{1ll/nat}ln$.$^{111/nat}ln-DOTA-sst_{3}-ODN-8$and$^{111/nat}lnDOTA-[4-NO_{2}-Phe-c(DCys-Tyr-DTrp-Lys-Thr-Cys)-DTyr-NH_{2}] (^{1ll/nat}lnDOTA-sst_{2}-ANT)$showed high sst₃- and sst₂-binding affinity, respectively. They did not trigger sst₃ or sst₂ internalization but prevented agonist-stimulated internalization.$^{111}ln-DOTA-sst_{3}ODN-8$and$^{111}1n-DOTA-sst_{2}-ANT$were injected intravenously into mice bearing sst₃- and sst₂-expressing tumors, and their biodistribution was monitored. In the sst₃-expressing tumors, strong accumulation of$^{111}ln-DOTA-sst_{3}-ODN-8$was observed, peaking at 1 h with 60% injected radioactivity per gram of tissue and remaining at a high level for >72 h. Excess of sst₃-ODN-8 blocked uptake. As a control, the potent agonist$^{111}1n-DOTA-[1-Nal^{3}]-octreotide$, with strong sst₃-binding and internalization properties showed a much lower and shorter-lasting uptake in sst3-expressing tumors. Similarly,$^{111}1n-DOTA-sst_{2}-ANT$was injected into mice bearing sst₂expressing tumors. Tumor uptake was considerably higher than with the highly potent sst₂-selective agonist$^{111}1n-diethylenetriaminepentaacetic$acid-[Tyr⁳,Thr⁸]-octreotide ($^{111}1n-DTPA-TATE$). Scatchard plots showed that antagonists labeled many more sites than agonists. Somatostatin antagonist radiotracers therefore are preferable over agonists for the in vivo targeting of sst₃- or sst₂-expressing tumors. Antagonist radioligands for other peptide receptors need to be evaluated in nuclear oncology as a result of this paradigm shift.

Persistent pain affects one in five people worldwide, often with severely debilitating consequences. While current treatments can be effective for mild or acute pain, they are largely inadequate for managing moderate to severe chronic pain, underscoring the urgent need for new therapeutics. The somatostatin receptor 4 (SSTR 4 ), expressed in sensory neurons of the peripheral nervous system, has recently emerged as a promising target for non-opioid pain relief. However, the presence of several closely related receptors with similar ligand-binding surfaces complicates the design of receptor-specific agonists. Here, we report the discovery of consomatin Fj1, a potent and selective SSTR 4 -targeting peptide derived from the venom gene repertoire of marine cone snails. Consomatin Fj1 is a mimetic of the endogenous hormone somatostatin but features a minimized receptor binding motif that provides target selectivity. Peripheral administration of synthetic consomatin Fj1 provides analgesia in mouse models of postoperative and neuropathic pain. Using structure–activity studies, we designed and functionally evaluated several Fj1 analogs, resulting in compounds with further improved potency and selectivity. These findings highlight the therapeutic potential of venom-derived peptides as a novel strategy for targeting the SSTR 4 and open new avenues for the development of effective treatments for persistent pain.

Combination therapy with somatostatin receptor ligand (SRL) plus pegvisomant for patients with acromegaly is recommended after a maximizing dose on monotherapy. Lower-dose combination regimens are not well studied. To compare cost-effectiveness and efficacy of 3 lower-dose combination regimens in controlled and uncontrolled acromegaly. Prospective, randomized, open-label, parallel arm study at a tertiary referral pituitary center. Adults with acromegaly regardless of response to prior SRL and biochemical control status at baseline, stratified by an SRL dose required for insulin-like growth factor (IGF)-I normalization during any 3-month period within 12 months preceding enrollment. Combination therapy for 24 to 32 weeks on arm A, high-dose SRL (lanreotide 120 mg/octreotide long-acting release [LAR] 30 mg) plus weekly pegvisomant (40-160 mg/week); arm B, low-dose SRL (lanreotide 60 mg/octreotide LAR 10 mg) plus weekly pegvisomant; or arm C, low-dose SRL plus daily pegvisomant (15-60 mg/day). Monthly treatment cost in each arm in participants completing ≥ 24 weeks of therapy. Sixty patients were enrolled and 52 were evaluable. Fifty of 52 (96%) demonstrated IGF-I control regardless of prior SRL responsiveness (arm A, 14/15 [93.3%]; arm B, 22/23 [95.7%]; arm C, 14/14 [100%]). Arm B was least costly (mean, $9837 ± 1375 per month), arm C was most expensive (mean, $22543 ± 11158 per month), and arm A had an intermediate cost (mean, $14261 ± 1645 per month). Approximately 30% of patients required pegvisomant dose uptitration. Rates of adverse events were all < 10%. Low-dose SRL plus weekly pegvisomant represents a novel dosing option for achieving cost-effective, optimal biochemical control in patients with uncontrolled acromegaly requiring combination therapy.

Primary cilia are compartmentalized sensory organelles present on the majority of neurons in the mammalian brain throughout adulthood. Recent evidence suggests that cilia regulate multiple aspects of neuronal development, including the maintenance of neuronal connectivity. However, whether ciliary signals can dynamically modulate postnatal circuit excitability is unknown. Here we show that acute cell-autonomous knockdown of ciliary signaling rapidly strengthens glutamatergic inputs onto cultured rat neocortical pyramidal neurons and increases spontaneous firing. This increased excitability occurs without changes to passive neuronal properties or intrinsic excitability. Further, the neuropeptide receptor somatostatin receptor 3 (SSTR3) is localized nearly exclusively to excitatory neuron cilia both in vivo and in culture, and pharmacological manipulation of SSTR3 signaling bidirectionally modulates excitatory synaptic inputs onto these neurons. Our results indicate that ciliary neuropeptidergic signaling dynamically modulates excitatory synapses and suggest that defects in this regulation may underlie a subset of behavioral and cognitive disorders associated with ciliopathies.

Altered brain somatostatin functions recently appeared as key elements for the pathogenesis of stress-related neuropsychiatric disorders. The hippocampus exerts an inhibitory feedback on stress but the mechanisms involved remain unclear. We investigated herein the role of hippocampal somatostatin receptor subtypes in both stress response and behavioral emotionality using C57BL/6, wild type and sst or sst knockout mice. Inhibitory effects of hippocampal infusions of somatostatin agonists on stress-induced hypothalamo-pituitary-adrenal axis (HPA) activity were tested by monitoring peripheral blood and local hippocampus corticosterone levels, the latter by using microdialysis. Anxiolytic and antidepressant-like effects were determined in the elevated-plus maze, open field, forced swimming, and stress-sensitive beam walking tests. Hippocampal injections of somatostatin analogs and sst or sst but not sst or sst receptor agonists produced rapid and sustained inhibition of HPA axis. sst agonists selectively produced anxiolytic-like behaviors whereas both sst and sst agonists had antidepressant-like effects. Consistent with these findings, high corticosterone levels and anxiety were found in sst KO mice and depressive-like behaviors observed in both sst KO and sst KO strains. Both hippocampal sst and sst receptors selectively inhibit stress-induced HPA axis activation but mediate anxiolytic and antidepressive effects through distinct mechanisms. Such results are to be accounted for in development of pathway-specific somatostatin receptor agents in the treatment of hypercortisolism (Cushing's disease) and stress-related neuropsychiatric disorders.

Neuroendocrine tumors (NETs) are a rare and heterogeneous class of neoplastic lesions, but their prevalence has increased significantly over the past three decades. These tumors are aggressive and difficult to treat. Improving diagnostic efficiency and treatment effectiveness is important for patients with neuroendocrine tumors. Radiopharmaceutical therapeutic diagnostics combines diagnosis and treatment technology and has broad prospects in precision medicine, especially for the early diagnosis and treatment of tumors. To compare the diagnostic advantages of radiolabeled somatostatin receptor agonists and antagonists for liver metastases from NETs and the disease control rate in NET patients. Systematic search of PubMed, Embase, Cochrane, Ovid, Scopus, and Web of Science databases up to 29 October 2024. Clinical trials of somatostatin receptor agonists and antagonists for NET diagnosis or treatment. Following PRISMA guidelines, data were independently extracted by two researchers. Pooled diagnostic or treatment effects and 95% CIs were reported using a random-effects meta-analysis model. Effect of somatostatin receptor agonists and antagonists in detecting liver metastases and disease control rate. Risk Ratio (RR) for liver metastasis detection and Effect Size (ES) for disease control rate were calculated. From 5291 articles, 52 were included in the meta-analysis. Radiolabeled somatostatin receptor antagonists were significantly more effective than agonists in detecting liver lesions (RR = 11.57, 95% CI: 4.10, 32.67). Disease control rates were higher with antagonists (ES = 0.90, 95% CI: 0.83, 0.96) compared to agonists (ES = 0.82, 95% CI: 0.78, 0.85, z = 2.12, p = 0.03). Radiolabeled somatostatin receptor antagonists outperform agonists in diagnosing hepatic lesions and controlling disease in NETs, highlighting their clinical superiority. This meta-analysis provides critical insights into the diagnostic and therapeutic efficacy of somatostatin receptor antagonists, and may offer a potential paradigm shift in the management of neuroendocrine tumors. Nevertheless, the smaller number of studies on antagonists may limit the generalizability of the findings and underscore the need for further clinical trials to validate these results.

Abstract Context First-generation somatostatin receptor ligands (fg-SRLs) represent the mainstay of medical therapy for acromegaly, but they provide biochemical control of disease in only a subset of patients. Various pretreatment biomarkers might affect biochemical response to fg-SRLs. Objective To identify clinical predictors of the biochemical response to fg-SRLs monotherapy defined as biochemical response (insulin-like growth factor (IGF)-1 ≤ 1.3 × ULN (upper limit of normal)), partial response (>20% relative IGF-1 reduction without normalization), and nonresponse (≤20% relative IGF-1 reduction), and IGF-1 reduction. Design Retrospective multicenter study. Setting Eight participating European centers. Methods We performed a meta-analysis of participant data from 2 cohorts (Rotterdam and Liège acromegaly survey, 622 out of 3520 patients). Multivariable regression models were used to identify predictors of biochemical response to fg-SRL monotherapy. Results Lower IGF-1 concentration at baseline (odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.72–0.95 IGF-1 ULN, P = .0073) and lower bodyweight (OR = 0.99, 95% CI 0.98–0.99 kg, P = .038) were associated with biochemical response. Higher IGF-1 concentration at baseline (OR = 1.40, (1.19–1.65) IGF-1 ULN, P ≤ .0001), the presence of type 2 diabetes (oral medication OR = 2.48, (1.43–4.29), P = .0013; insulin therapy OR = 2.65, (1.02–6.70), P = .045), and higher bodyweight (OR = 1.02, (1.01–1.04) kg, P = .0023) were associated with achieving partial response. Younger patients at diagnosis are more likely to achieve nonresponse (OR = 0.96, (0.94–0.99) year, P = .0070). Baseline IGF-1 and growth hormone concentration at diagnosis were associated with absolute IGF-1 reduction (β = 0.90, standard error (SE) = 0.02, P ≤ .0001 and β  = 0.002, SE = 0.001, P = .014, respectively). Conclusion Baseline IGF-1 concentration was the best predictor of biochemical response to fg-SRL, followed by bodyweight, while younger patients were more likely to achieve nonresponse.

BackgroundAcromegaly patients, even those with IGF-1 values within the normal range receiving somatostatin receptor ligands (SRLs), often suffer from significant symptoms. It is not known to what extent patients’ medical providers are aware of the frequency and severity of acromegaly symptoms or level of treatment satisfaction with SRLs. This study sought to examine the concordance between outcomes reported by acromegaly patients treated with long-acting SRLs and those perceived by their medical provider.MethodsUS acromegaly patients on a stable dose of SRL and seen by their medical provider in the past year completed an online survey which included the Acro-TSQ. Their medical providers were interviewed about the perception of their patient’s symptoms, level of control, and general health, and completed relevant portions of the Acro-TSQ. Concordance between patient and medical provider reported data was examined.ResultsMedical providers reported that their patients experienced acromegaly symptoms on a regular basis, however, there was poor agreement between patients and medical providers on the frequency, severity, and pattern of symptoms, as well as on the severity of injection site reactions and multiple domains of the Acro-TSQ, with patients generally reporting symptoms and injection site reactions more often and with higher severity than medical providers.ConclusionsMedical providers were aware that their patients who were receiving a stable dose of SRL regularly experienced acromegaly symptoms. Addressing discordance in patient- and medical provider-reported frequency and severity of acromegaly symptoms and injection site reactions by facilitating better communication may improve care of acromegaly patients.

The melanin-concentrating hormone (MCH) system is involved in numerous functions, including energy homeostasis, food intake, sleep, stress, mood, aggression, reward, maternal behavior, social behavior, and cognition. In rodents, MCH acts on MCHR1, a G protein-coupled receptor, which is widely expressed in the brain and abundantly localized to neuronal primary cilia. Cilia act as cells’ antennas and play crucial roles in cell signaling to detect and transduce external stimuli to regulate cell differentiation and migration. Cilia are highly dynamic in terms of their length and morphology; however, it is not known if cilia length is causally regulated by MCH system activation in vivo. In the current work, we examined the effects of activation and inactivation of MCH system on cilia lengths by using different experimental models and methodologies, including organotypic brain slice cultures from rat prefrontal cortex (PFC) and caudate–putamen (CPu), in vivo pharmacological (MCHR1 agonist and antagonist GW803430), germline and conditional genetic deletion of MCHR1 and MCH, optogenetic, and chemogenetic (designer receptors exclusively activated by designer drugs (DREADD)) approaches. We found that stimulation of MCH system either directly through MCHR1 activation or indirectly through optogenetic and chemogenetic-mediated excitation of MCH-neuron, caused cilia shortening, detected by the quantification of the presence of ADCY3 protein, a known primary cilia marker. In contrast, inactivation of MCH signaling through pharmacological MCHR1 blockade or through genetic manipulations — germline deletion of MCHR1 and conditional ablation of MCH neurons — induced cilia lengthening. Our study is the first to uncover the causal effects of the MCH system in the regulation of the length of brain neuronal primary cilia. These findings place MCH system at a unique position in the ciliary signaling in physiological and pathological conditions and implicate MCHR1 present at primary cilia as a potential therapeutic target for the treatment of pathological conditions characterized by impaired primary cilia function associated with the modification of its length.