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302 result(s) for "Signoretti, S."
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Consensus statement from the international consensus meeting on post-traumatic cranioplasty
Background Due to the lack of high-quality evidence which has hindered the development of evidence-based guidelines, there is a need to provide general guidance on cranioplasty (CP) following traumatic brain injury (TBI), as well as identify areas of ongoing uncertainty via a consensus-based approach. Methods The international consensus meeting on post-traumatic CP was held during the International Conference on Recent Advances in Neurotraumatology (ICRAN), in Naples, Italy, in June 2018. This meeting was endorsed by the Neurotrauma Committee of the World Federation of Neurosurgical Societies (WFNS), the NIHR Global Health Research Group on Neurotrauma, and several other neurotrauma organizations. Discussions and voting were organized around 5 pre-specified themes: (1) indications and technique, (2) materials, (3) timing, (4) hydrocephalus, and (5) paediatric CP. Results The participants discussed published evidence on each topic and proposed consensus statements, which were subject to ratification using anonymous real-time voting. Statements required an agreement threshold of more than 70% for inclusion in the final recommendations. Conclusions This document is the first set of practical consensus-based clinical recommendations on post-traumatic CP, focusing on timing, materials, complications, and surgical procedures. Future research directions are also presented.
p63 Is a Prostate Basal Cell Marker and Is Required for Prostate Development
The p53 homologue p63 encodes for different isotypes able to either transactivate p53 reporter genes ( TAp63) or act as p53-dominant-negatives ( ΔNp63). p63 is expressed in the basal cells of many epithelial organs and its germline inactivation in the mouse results in agenesis of organs such as skin appendages and the breast. Here, we show that prostate basal cells, but not secretory or neuroendocrine cells, express p63. In addition, prostate basal cells in culture predominantly express the ΔNp63α isotype. In contrast, p63 protein is not detected in human prostate adenocarcinomas. Finally, and most importantly, p63 (−/−) mice do not develop the prostate. These results indicate that p63 is required for prostate development and support the hypothesis that basal cells represent and/or include prostate stem cells. Furthermore, our results show that p63 immunohistochemistry may be a valuable tool in the differential diagnosis of benign versus malignant prostatic lesions.
Loss of the Lkb1 tumour suppressor provokes intestinal polyposis but resistance to transformation
Germline mutations in LKB1 (also known as STK11 ) are associated with Peutz–Jeghers syndrome (PJS), a disorder with predisposition to gastrointestinal polyposis and cancer 1 . PJS polyps are unusual neoplasms characterized by marked epithelial and stromal overgrowth but have limited malignant potential 2 . Here we show that Lkb1 +/- mice develop intestinal polyps identical to those seen in individuals affected with PJS. Consistent with this in vivo tumour suppressor function, Lkb1 deficiency prevents culture-induced senescence without loss of Ink4a / Arf or p53 . Despite compromised mortality, Lkb1 -/- mouse embryonic fibroblasts show resistance to transformation by activated Ha- Ras either alone or with immortalizing oncogenes. This phenotype is in agreement with the paucity of mutations in Ras seen in PJS polyps 3 , 4 and suggests that loss of Lkb1 function as an early neoplastic event renders cells resistant to subsequent oncogene-induced transformation. In addition, the Lkb1 transcriptome shows modulation of factors linked to angiogenesis, extracellular matrix remodelling, cell adhesion and inhibition of Ras transformation. Together, our data rationalize several features of PJS polyposis—notably its peculiar histopathological presentation and limited malignant potential—and place Lkb1 in a distinct class of tumour suppressors.
Cox-2 inhibition enhances the activity of sunitinib in human renal cell carcinoma xenografts
Background: Sunitinib (Su), a tyrosine kinase inhibitor of VEGFR, is effective at producing tumour response in clear cell renal cell carcinoma (cRCC), but resistance to therapy is inevitable. As COX-2 is a known mediator of tumour growth, we explored the potential benefit of COX-2 inhibition in combination with VEGFR inhibition in attempts at delaying tumour progression on Su. Methods: COX-2 expression was compared with areas of hypoxia in tumours that progressed on Su vs untreated tumours. Mice bearing human cRCC xenografts were treated with Su and the COX-2 inhibitor, celecoxib, and the effects on tumour growth were assessed. Sequential vs concurrent regimens were compared. Results: COX-2 expression was increased in cRCC xenografts in areas of tumour hypoxia. The combination of Su and celecoxib achieved longer times to tumour progression compared to treatment with either agent alone or to untreated control animals in four models. This effect was seen with concurrent but not with sequential therapy. Conclusion: COX-2 inhibition can extend the effectiveness of VEGFR inhibition. This effect is dependent on the timing of therapy. Clinical trials combining Su and COX-2 inhibitors should be considered as a means delaying time to progression on sunitinib in patients with metastatic cRCC.
N-Acetylaspartate Reduction as a Measure of Injury Severity and Mitochondrial Dysfunction Following Diffuse Traumatic Brain Injury
N-Acetylaspartate (NAA) is considered a neuron-specific metabolite and its reduction a marker of neuronal loss. The objective of this study was to evaluate the time course of NAA changes in varying grades of traumatic brain injury (TBI), in concert with the disturbance of energy metabolites (ATP). Since NAA is synthesized by the mitochondria, it was hypothesized that changes in NAA would follow ATP. The impact acceleration model was used to produce three grades of TBI. Sprague-Dawley rats were divided into the following four groups: sham control (n = 12); moderate TBI (n = 36); severe TBI (n = 36); and severe TBI coupled with hypoxia-hypotension (n = 16). Animals were sacrificed at different time points ranging from 1 min to 120 h postinjury, and the brain was processed for high-performance liquid chromatography (HPLC) analysis of NAA and ATP. After moderate TBI, NAA reduced gradually by 35% at 6 h and 46% at 15 h, accompanied by a 57% and 45% reduction in ATP. A spontaneous recovery of NAA to 86% of baseline at 120 h was paralleled by a restoration in ATP. In severe TBI, NAA fell suddenly and did not recover, showing critical reduction (60%) at 48 h. ATP was reduced by 70% and also did not recover. Maximum NAA and ATP decrease occurred with secondary insult (80% and 90%, respectively, at 48 h). These data show that, at 48 h post diffuse TBI, reduction of NAA is graded according to the severity of insult. NAA recovers if the degree of injury is moderate and not accompanied by secondary insult. The highly similar time course and correlation between NAA and ATP supports the notion that NAA reduction is related to energetic impairment.
Diagnostic Utility of Immunohistochemical Staining for p63, a Sensitive Marker of Prostatic Basal Cells
Diagnostically reliable identification of prostatic basal cells has depended on staining for high molecular weight cytokeratin. The diagnosis of malignancy is often based on the absence of basal cells. False-negative staining is occasionally observed. Thus, a second method of identifying basal cells might prove useful. Selective expression of p63, a homologue of p53, has been demonstrated in prostatic basal cells. We investigated the diagnostic utility of p63 staining in 70 consecutive specimens for which the differential diagnosis included prostatic adenocarcinoma: 68 needle biopsies and 2 transurethral resection blocks. High molecular weight cytokeratin staining was the gold standard when material was available. A total of 61 specimens were diagnosed as carcinoma, 4 as atrophy, 2 as high-grade prostatic intraepithelial neoplasia, 2 as unclassified collections of benign glands, and 1 as carcinoma versus high-grade prostatic intraepithelial neoplasia. Sections mounted on charged slides were used for p63 staining for 14 specimens. Sections previously hematoxylin and eosin stained on uncharged slides were used for 56 specimens. In every case in which there was successful p63 staining (55 specimens), basal cells in benign lesions were properly marked and other cell types were not stained. Uninformative staining in the remaining 15 specimens was due to failure of tissue adherence in 14 specimens in which sections were on uncharged slides and, in 1 specimen, to poor positive internal control staining of benign glands. Thus, p63 staining was informative in 55 of 56 specimens (98%) for which there was material for examination. No case with satisfactory p63 and high molecular weight staining showed disagreement between the two stains. An additional group of 21 transurethral resection specimens was stained (p63 and high molecular weight cytokeratin). There was less false-negative staining for p63 compared with the case of high molecular weight cytokeratin. No false-positive staining was seen. We conclude that p63 staining is at least as sensitive and specific for the identification of basal cells in diagnostic prostate specimens as is high molecular weight cytokeratin staining.
p63-expressing cells are the stem cells of developing prostate, bladder, and colorectal epithelia
The tumor protein p63 (p63), and more specifically the NH2-terminal truncated (ΔN) p63 isoform, is a marker of basal epithelial cells and is required for normal development of several epithelial tissues, including the bladder and prostate glands. Although p63-expressing cells are proposed to be the stem cells of the developing prostate epithelium and bladder urothelium, cell lineages in these endoderm-derived epithelia remain highly controversial, and rigorous lineage tracing studies are warranted. Here, we generated knock-in mice expressing Cre recombinase (Cre) under the control of the endogenous ΔNp63 promoter. Heterozygote ΔNp63 ⁺/Cʳᵉ mice were phenotypically normal and fertile. Cre-mediated recombination in ΔNp63 ⁺/Cʳᵉ;ROSA26 ᴱYFᴾ reporter mice faithfully recapitulated the pattern of ΔNp63 expression and were useful for genetic lineage tracing of ΔNp63-expressing cells of the caudal endoderm in vivo. We found that ΔNp63-positive cells of the urogenital sinus generated all epithelial lineages of the prostate and bladder, indicating that these cells represent the stem/progenitor cells of those epithelia during development. We also observed ΔNp63 expression in caudal gut endoderm and the contribution of ΔNp63-positive cells to the stem/progenitor compartment of adult colorectal epithelium. Because p63 is a master regulator of stratified epithelial development, this finding provides a unique developmental insight into the cell of origin of squamous cell metaplasia and squamous cell carcinoma of the colon.
Stabilization of β-catenin induces lesions reminiscent of prostatic intraepithelial neoplasia, but terminal squamous transdifferentiation of other secretory epithelia
The present study documents that stabilization of beta-catenin is sufficient to induce lesions reminiscent of prostate intraepithelial neoplasia (PIN). Such lesions were present in all compound mutant mice and all prostate acini expressing stabilized beta-catenin. High grade PIN-like lesions resembling early human prostate cancer were detected as early as 10 weeks of age. Surprisingly, stabilization of beta-catenin in other secretory epithelia including salivary, preputial, harderian, and mammary glands induced extensive squamous metaplasia and keratinization associated with terminal differentiation of the target cells, but failed to cause neoplastic transformation. Epidermal hyperplasia, hair follicle cysts, and odontomas were also observed. The prostatic lesions exhibited upregulation of c-myc, increased rate of cellular proliferation, loss of the Na-K-Cl co-transporter NKCC1, and expression of androgen receptor. Basal cell markers such as p63 and keratin 5 were not expressed by the masses of PIN-like lesions, but were present in small foci of proliferating beta-catenin expressing basal cells. Our observations indicate that beta-catenin stabilization is a crucial event for the initiation of PIN-like lesions, but induces squamous metaplasia rather than tumorigenesis in secretory epithelia other than the prostate.
Essential roles of PI(3)K–p110β in cell growth, metabolism and tumorigenesis
Insulin-induced changes in tumours The two most widely expressed isoforms of class 1 PI3 kinases are p110alpha and p110beta. Previously, the p110-alpha isoform has been implicated in growth factor and insulin signalling, as well as in tumorigenesis. Now the analysis of mutant mice reveals a major role for p110-beta in the regulation of insulin-dependent metabolic changes and in tumour formation. Interestingly, some of the effects are mediated by a kinase-independent function of p110-beta. On activation by receptors, the ubiquitously expressed class IA isoforms (p110α and p110β) of phosphatidylinositol-3-OH kinase (PI(3)K) generate lipid second messengers, which initiate multiple signal transduction cascades 1 , 2 , 3 , 4 , 5 . Recent studies have demonstrated specific functions for p110α in growth factor and insulin signalling 6 , 7 , 8 . To probe for distinct functions of p110β, we constructed conditional knockout mice. Here we show that ablation of p110β in the livers of the resulting mice leads to impaired insulin sensitivity and glucose homeostasis, while having little effect on phosphorylation of Akt, suggesting the involvement of a kinase-independent role of p110β in insulin metabolic action. Using established mouse embryonic fibroblasts, we found that removal of p110β also had little effect on Akt phosphorylation in response to stimulation by insulin and epidermal growth factor, but resulted in retarded cell proliferation. Reconstitution of p110β-null cells with a wild-type or kinase-dead allele of p110β demonstrated that p110β possesses kinase-independent functions in regulating cell proliferation and trafficking. However, the kinase activity of p110β was required for G-protein-coupled receptor signalling triggered by lysophosphatidic acid and had a function in oncogenic transformation. Most strikingly, in an animal model of prostate tumour formation induced by Pten loss, ablation of p110β (also known as Pik3cb ), but not that of p110α (also known as Pik3ca ), impeded tumorigenesis with a concomitant diminution of Akt phosphorylation. Taken together, our findings demonstrate both kinase-dependent and kinase-independent functions for p110β, and strongly indicate the kinase-dependent functions of p110β as a promising target in cancer therapy.