Designing Chimeric Molecules for Drug Discovery by Leveraging Chemical Biology.

After the first seed concept introduced in the 18th century, different disciplines have attributed different names to dual-functional molecules depending on their application, including bioconjugates, bifunctional compounds, multitargeting molecules, chimeras, hybrids, engineered compounds. However, these engineered constructs share a general structure: a first component that targets a specific cell and a second component that exerts the pharmacological activity. A stable or cleavable linker connects the two modules of a chimera. Herein, we discuss the recent advances in the rapidly expanding field of chimeric molecules leveraging chemical biology concepts. This Perspective is focused on bifunctional compounds in which one component is a lead compound or a drug. In detail, we discuss chemical features of chimeric molecules and their use for targeted delivery and for target engagement studies

Negative Pigment Network Identifies a Peculiar Melanoma Subtype and Represents a Clue to Melanoma Diagnosis: A Dermoscopic Study of 401 Melanomas

The dermoscopic descriptor "negative pigment network" (NPN) has been reported in several types of melanocytic and non-melanocytic lesions, although it has a higher frequency of association with melanoma and Spitz naevus. In a study of 401 consecutive melanomas, excluding facial, acral and mucosal locations, the frequency and variability of NPN were investigated, and the results of NPN correlated with clinical and histopathological data. NPN of any extension was found in 27% of melanomas, most frequently invasive and arising from a naevus on the trunk of young subjects. Seven percent of melanomas in the study population showed presence of NPN in more than half of the lesion area; most of these did not show typical dermoscopic melanoma features. The authors propose a new melanoma subtype, in which extensive NPN should be considered as a diagnostic indicator

Clinical Review of Mucosal Melanoma: The 11-Year Experience of a Referral Center

Introduction: Mucosal melanoma is a rare neoplasm. Late diagnosis is caused by occult anatomic sites and scarcity of symptoms. Novel biological therapies have now become available. Demographic, therapeutical and survival records on mucosal melanoma are scarce. Objectives: To provide an 11-year retrospective clinical review of real-world data on mucosal melanomas managed in a tertiary referral center in Italy. Methods: We included patients with histopathological mucosal melanoma diagnoses from January 2011 to December 2021. Data were collected until the last known follow-up or death. Survival analysis was performed. Results: Among 33 patients, we found 9 sinonasal, 13 anorectal and 11 urogenital mucosal melanomas (median age 82, females 66.7%). Eighteen cases (54.5%) presented with metastasis (p<0.05). In the urogenital subgroup, only 4 patients (36.4%) had metastasis at diagnosis, all in regional lymph nodes. Sinonasal melanomas were surgically managed with a debulking procedure (44.4%); every case of anorectal and urogenital melanomas underwent radical surgery (30.8% and 45.5%). Fifteen patients were treated with biological therapy (p<0.05). Radiation therapy was used in all melanomas of the sinonasal region (p<0.05). Overall survival was longer for urogenital melanomas (26 months). Univariate analysis showed an increased hazard ratio for death in patients with metastasis. A negative prognostic value of metastatic status was reported by the multivariate model, while administration of first-line immunotherapy demonstrated a protective role. Conclusions: At diagnosis, the absence of metastatic disease is the most relevant factor that influences the survival of mucosal melanomas. Moreover, the use of immunotherapy might prolong the survival of metastatic mucosal melanoma patients

Functional characterization of a CDKN1B mutation in a Sardinian kindred with multiple endocrine neoplasia type 4 (MEN4)

Inactivating germline mutations of the CDKN1B gene, encoding for the nuclear cyclin-dependent kinase inhibitor p27kip1 protein, have been reported in patients with multiple endocrine neoplasia type 4 (MEN4), a MEN1-like phenotype without MEN1 mutations. The aim of this study was to in vitro characterize the germline CDKN1B mutation c.374_375delCT (S125X) we detected in a patient with MEN4. The proband was affected by multiglandular primary hyperparathyroidism and gastro-entero-pancreatic tumors. We carried out subcellular localization experiments transfecting into eukaryotic HeLa and GH3 cell lines plasmid vectors expressing the CDKN1B wild type (wt) or mutant cDNA. Western blot studies showed that fusion proteins were expressed at equal levels. The mutated protein was shorter compared to the wt protein and lacked the highly conserved C-terminal domain, which includes the bipartite nuclear localization signal at amino acids 152/153 and 166/168. In HeLa and GH3 cells wt p27 localized in the nucleus whereas the p27_S125X protein was retained in the cytoplasm predicting the loss of tumor suppressive function. The proband's tumoral parathyroid tissue did not show allelic loss, since wt and mutant alleles were both present by sequencing the somatic DNA. Immunohistochemistry showed a complete loss of nuclear p27 expression in the parathyroid adenoma removed by the patient at the second surgery. In conclusion, our study confirms the pathogenic role of the c.374_375delCT CDKN1B germline mutation in a patient with MEN4

Quantitative evaluation of healthy epidermis by means of multiphoton microscopy and fluorescence lifetime imaging microscopy

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Mutational and large deletion study of genes implicated in hereditary forms of primary hyperparathyroidism and correlation with clinical features

The aim of this study was to carry out genetic screening of the MEN1, CDKN1B and AIP genes, both by direct sequencing of the coding region and multiplex ligation-dependent probe amplification (MLPA) assay in the largest monocentric series of Italian patients with Multiple Endocrine Neoplasia type 1 syndrome (MEN1) and Familial Isolated Hyperparathyroidism (FIHP). The study also aimed to describe and compare the clinical features of MEN1 mutation-negative and mutation-positive patients during long-term follow-up and to correlate the specific types and locations of MEN1 gene mutations with onset and aggressiveness of the main MEN1 manifestations. A total of 69 index cases followed at the Endocrinology Unit in Pisa over a period of 19 years, including 54 MEN1 and 15 FIHP kindreds were enrolled. Seven index cases with MEN1 but MEN1 mutation-negative, followed at the University Hospital of Cagliari, were also investigated. FIHP were also tested for CDC73 and CaSR gene alterations. MEN1 germline mutations were identified in 90% of the index cases of familial MEN1 (F-MEN1) and in 23% of sporadic cases (S-MEN1). MEN1 and CDC73 mutations accounted for 13% and 7% of the FIHP cohort, respectively. A CDKN1B mutation was identified in one F-MEN1. Two AIP variants of unknown significance were detected in two MEN1-negative S-MEN1. A MEN1 positive test best predicted the onset of all three major MEN1-related manifestations or parathyroid and gastro-entero-pancreatic tumors during follow-up. A comparison between the clinical characteristics of F and S-MEN1 showed a higher prevalence of a single parathyroid disease and pituitary tumors in sporadic compared to familial MEN1 patients. No significant correlation was found between the type and location of MEN1 mutations and the clinical phenotype. Since all MEN1 mutation-positive sporadic patients had a phenotype resembling that of familial MEN1 (multiglandular parathyroid hyperplasia, a prevalence of gastro-entero-pancreatic tumors and/or the classic triad) we might hypothesize that a subset of the sporadic MEN1 mutation-negative patients could represent an incidental coexistence of sporadic primary hyperparathyroidism and pituitary tumors or a MEN1 phenocopy, in our cohort, as in most cases described in the literature

Identification and functional characterization of loss-of-function mutations of the calcium-sensing receptor in four italian kindreds with familial hypocalciuric hypercalcemia

Objective: Identification and characterization of calcium-sensing receptor (CASR) mutations in four unrelated Italian kindreds with familial hypocalciuric hypercalcemia. Design: Clinical evaluation and genetic analysis of CASR gene. Functional characterization of mutated CASRs. Methods: Direct sequencing of CASR gene in genomic DNA. Studies of CASR-mediated increases in cytosolic calcium concentration [Ca2C]i in CASR-transfected COS-7 cells in vitro. Results: Four unreported heterozygous CASR mutations were identified, including three missense (H595Y, P748H, and C765W) and one splice site (IVS2C1GOC) mutation. The H595Y, P748H, and C765W mutant receptors, although expressed at normal levels on the cell surface, showed a reduced response in [Ca2C]i relative to the wildtype (WT) CASR to increasing extracellular calcium concentrations. Cotransfection experiments showed that the H595Y and P748H mutants did not affect the apparent affinity of the WT CASR for calcium, suggesting that they do not exert a dominant-negative effect. On the other hand, the co-transfected C765W mutant decreased the maximum response of the WT CASR to calcium, suggesting that it may reduce the effective concentration of the normal CASR on the cell surface or impair its maximal signaling capacity. Conclusions: Four CASR mutations were identified. The reduced functional responses to extracellular calcium and normal expression of the mutant receptors suggest that conformational changes account for altered CASR activity. Moreover, a reduced complement of normal CASRs in these heterozygous patients, perhaps combined with a mutant receptor-induced decrease in maximal activity of the WT receptor, may contribute to defective calcium-sensing in vivo.L'articolo è disponibile sul sito dell'editore http://www.euro-endo.org/default.asp

Chroman-4-One Derivatives Targeting Pteridine Reductase 1 and Showing Anti-Parasitic Activity

Flavonoids have previously been identified as antiparasitic agents and pteridine reductase 1 (PTR1) inhibitors. Herein, we focus our attention on the chroman-4-one scaffold. Three chroman-4-one analogues (1-3) of previously published chromen-4-one derivatives were synthesized and biologically evaluated against parasitic enzymes (Trypanosoma brucei PTR1-TbPTR1 and Leishmania major-LmPTR1) and parasites (Trypanosoma brucei and Leishmania infantum). A crystal structure of TbPTR1 in complex with compound 1 and the first crystal structures of LmPTR1-flavanone complexes (compounds 1 and 3) were solved. The inhibitory activity of the chroman-4-one and chromen-4-one derivatives was explained by comparison of observed and predicted binding modes of the compounds. Compound 1 showed activity both against the targeted enzymes and the parasites with a selectivity index greater than 7 and a low toxicity. Our results provide a basis for further scaffold optimization and structure-based drug design aimed at the identification of potent anti-trypanosomatidic compounds targeting multiple PTR1 variants

Case report: Early-onset osteoporosis in a patient carrying a novel heterozygous variant of the WNT1 gene

Article presents a case study of a 35 year-old Caucasian woman who experienced multiple vertebral fractures two months after her second pregnancy. The results suggest a potential role of heterozygous WNT1 variants in the pathogenesis of early-onset osteoporosis. The authors suggest that teriparatide is one of the most appropriate available therapies for such cases

Profiling of Flavonol Derivatives for the Development of Antitrypanosomatidic Drugs

Flavonoids represent a potential source of new antitrypanosomatidic leads. Starting from a library of natural products, we combined target-based screening on pteridine reductase 1 with phenotypic screening on Trypanosoma brucei for hit identification. Flavonols were identified as hits, and a library of 16 derivatives was synthesized. Twelve compounds showed EC50 values against T. brucei below 10 \u3bcM. Four X-ray crystal structures and docking studies explained the observed structure-activity relationships. Compound 2 (3,6-dihydroxy-2-(3-hydroxyphenyl)-4H-chromen-4-one) was selected for pharmacokinetic studies. Encapsulation of compound 2 in PLGA nanoparticles or cyclodextrins resulted in lower in vitro toxicity when compared to the free compound. Combination studies with methotrexate revealed that compound 13 (3-hydroxy-6-methoxy-2-(4-methoxyphenyl)-4H-chromen-4-one) has the highest synergistic effect at concentration of 1.3 \u3bcM, 11.7-fold dose reduction index and no toxicity toward host cells. Our results provide the basis for further chemical modifications aimed at identifying novel antitrypanosomatidic agents showing higher potency toward PTR1 and increased metabolic stability