RESUMEN
The peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTA-octreotate (LuTate) is recommended for different types of neuroendocrine tumors (NETs) which overexpress somatostatin receptors (SSTR). A combination with chemotherapy improves objective response to LuTate in NET patients and here we characterized chemotherapy-induced upregulation of SSTR2 receptors as a cause for this improved response to LuTate. The NET cell lines with low (BON-1) or relatively high (NCI-H727) SSTR2-expression levels, and non-NET cancer and normal cells were treated with chemotherapeutic drugs and assessed for upregulation of SSTR2. We report that an exposure to low or high doses of drugs, such as temozolomide for 24 h or 5 day results in upregulation of SSTR2 between 3-7 days, increased LuTate uptake and decreased rate of cell proliferation. This effect is at the level of SSTR2-mRNA and is more pronounced in low SSTR2 expressing BON-1 than in high SSTR2 expressing NCI-H727 or non-NET cancer or normal cells. Thus, a properly timed pre-treatment with low-dose chemotherapy could not only improve therapeutic efficacy of LuTate in NET patients who are presently eligible for PRRT, but also allow PRRT to be administered to patients with low SSTR-expressing NETs, who would otherwise not respond to this modality because of insufficient radiation delivery.
RESUMEN
Purpose: To demonstrate the effectiveness of combining retinal phenotyping and focused variant filtering from genome sequencing (GS) in identifying deep intronic disease causing variants in inherited retinal dystrophies. Methods: Affected members from three pedigrees with classical enhanced S-cone syndrome (ESCS; Pedigree 1), congenital stationary night blindness (CSNB; Pedigree 2), and achromatopsia (ACHM; Pedigree 3), respectively, underwent detailed ophthalmologic evaluation, optical coherence tomography, and electroretinography. The probands underwent panel-based genetic testing followed by GS analysis. Minigene constructs (NR2E3, GPR179 and CNGB3) and patient-derived cDNA experiments (NR2E3 and GPR179) were performed to assess the functional effect of the deep intronic variants. Results: The electrophysiological findings confirmed the clinical diagnosis of ESCS, CSNB, and ACHM in the respective pedigrees. Panel-based testing revealed heterozygous pathogenic variants in NR2E3 (NM_014249.3; c.119-2A>C; Pedigree 1) and CNGB3 (NM_019098.4; c.1148delC/p.Thr383Ilefs*13; Pedigree 3). The GS revealed heterozygous deep intronic variants in Pedigrees 1 (NR2E3; c.1100+1124G>A) and 3 (CNGB3; c.852+4751A>T), and a homozygous GPR179 variant in Pedigree 2 (NM_001004334.3; c.903+343G>A). The identified variants segregated with the phenotype in all pedigrees. All deep intronic variants were predicted to generate a splice acceptor gain causing aberrant exonization in NR2E3 [89 base pairs (bp)], GPR179 (197 bp), and CNGB3 (73 bp); splicing defects were validated through patient-derived cDNA experiments and/or minigene constructs and rescued by antisense oligonucleotide treatment. Conclusions: Deep intronic mutations contribute to missing heritability in retinal dystrophies. Combining results from phenotype-directed gene panel testing, GS, and in silico splice prediction tools can help identify these difficult-to-detect pathogenic deep intronic variants.
Asunto(s)
Predisposición Genética a la Enfermedad/genética , Variación Genética/genética , Intrones/genética , Distrofias Retinianas/genética , Secuenciación Completa del Genoma , Adolescente , Niño , Preescolar , Defectos de la Visión Cromática/genética , Simulación por Computador , Electroforesis en Gel de Agar , Exones/genética , Enfermedades Hereditarias del Ojo/genética , Estudios de Asociación Genética , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Células HEK293 , Humanos , Masculino , Miopía/genética , Ceguera Nocturna/genética , Linaje , Reacción en Cadena de la Polimerasa , Isoformas de Proteínas/genética , Degeneración Retiniana/genética , Distrofias Retinianas/patología , Trastornos de la Visión/genética , Secuenciación Completa del Genoma/métodos , Adulto JovenRESUMEN
Tau is a microtubule-associated protein involved in Alzheimer's disease. However, little is known on its physiological function in the healthy central nervous system. Here, we observed that the expression of Tau isoforms was modulated by neuronal maturation and visual experience in the mouse retina and in the visual cortex. The visual function of wild-type (WT) and Tau knockout (KO) mice was evaluated using the optokinetic reflex (OKR), an innate visuomotor behavior, and by electroretinography. Visual tests did not reveal functional impairments in young adult and old Tau KO animals. Moreover, monocular deprivation (MD) was used to increase OKR sensitivity, a plasticity phenomenon depending on the visual cortex. MD-induced OKR sensitivity enhancement was significantly stronger in Tau KO than in WT mice suggesting that Tau restricts visual plasticity. In addition, human Tau expression did not affect visual function and plasticity in a mouse tauopathy model, relative to WT controls. Our results unveil a novel function for Tau in the adaptive mechanisms of plasticity operating in the adult brain subjected to sensory experience changes.
