Rubén Cabanillas

Autophagy is essential for mouse sense of balance

Autophagy is an evolutionarily conserved process that is essential for cellular homeostasis and organismal viability in eukaryotes. However, the extent of its functions in higher-order processes of organismal physiology and behavior is still unknown. Here, we report that autophagy is essential for the maintenance of balance in mice and that its deficiency leads to severe balance disorders. We generated mice deficient in autophagin-1 protease (Atg4b) and showed that they had substantial systemic reduction of autophagic activity. Autophagy reduction occurred through defective proteolytic processing of the autophagosome component LC3 and its paralogs, which compromised the rate of autophagosome maturation. Despite their viability, Atg4b-null mice showed unusual patterns of behavior that are common features of inner ear pathologies. Consistent with this, Atg4b-null mice showed defects in the development of otoconia, organic calcium carbonate crystals essential for sense of balance (equilibrioception). Furthermore, these abnormalities were exacerbated in Atg5-/- mice, which completely lack the ability to perform autophagy, confirming that autophagic activity is necessary for otoconial biogenesis. Autophagy deficiency also led to impaired secretion and assembly of otoconial core proteins, thus hampering otoconial development. Taken together, these results describe an essential role for autophagy in inner ear development and equilibrioception and open new possibilities for understanding and treating human balance disorders, which are of growing relevance among the elderly population.

Exome sequencing and functional analysis identifies BANF1 mutation as the cause of a hereditary progeroid syndrome.

Accelerated aging syndromes represent a valuable source of information about the molecular mechanisms involved in normal aging. Here, we describe a progeroid syndrome that partially phenocopies Hutchinson-Gilford progeria syndrome (HGPS) but also exhibits distinctive features, including the absence of cardiovascular deficiencies characteristic of HGPS, the lack of mutations in LMNA and ZMPSTE24, and a relatively long lifespan of affected individuals. Exome sequencing and molecular analysis in two unrelated families allowed us to identify a homozygous mutation in BANF1 (c.34G>A [p.Ala12Thr]), encoding barrier-to-autointegration factor 1 (BAF), as the molecular abnormality responsible for this Mendelian disorder. Functional analysis showed that fibroblasts from both patients have a dramatic reduction in BAF protein levels, indicating that the p.Ala12Thr mutation impairs protein stability. Furthermore, progeroid fibroblasts display profound abnormalities in the nuclear lamina, including blebs and abnormal distribution of emerin, an interaction partner of BAF. These nuclear abnormalities are rescued by ectopic expression of wild-type BANF1, providing evidence for the causal role of this mutation. These data demonstrate the utility of exome sequencing for identifying the cause of rare Mendelian disorders and underscore the importance of nuclear envelope alterations in human aging.

Overexpression of Focal Adhesion Kinase in Head and Neck Squamous Cell Carcinoma Is Independent of fak Gene Copy Number

The development of human malignancies can involve the aberrant regulation of intracellular signal transduction pathways that regulate cell-extracellular matrix interactions. Purpose: In the current study, we aimed to evaluate focal adhesion kinase (FAK) at both genetic and protein expression levels in head and neck squamous cell carcinomas (HNSCC) and to explore the prognostic significance of FAK. Experimental Design: A total of 211 tissue specimens, including 147 primary tumors, 56 lymph node metastases, 3 benign hyperplasias, and 5 dysplasias, were analyzed using immunohistochemistry. The fak gene dosage was determined in 33 tumors. Correlations among DNA, protein, and clinicopathologic variables were analyzed. Results: FAK protein was overexpressed in HNSCCs compared with corresponding normal mucosa. High expression levels were found in 62% of the samples. Positive immunostaining was also detected in benign hyperplasias and preinvasive dysplastic lesions. All lymph node metastases examined showed FAK overexpression, with significant correlation with the expression in matched primary tumor. DNA copy number ratios for fak were higher in 39% of the tumors compared with normal mucosa. However, elevated FAK expression did not correlate with gains on DNA level, and not all cases with an amplification of the fak gene displayed protein overexpression. Similar data were obtained in five HNSCC-derived cell lines, in which FAK mRNA levels were precisely correlated with FAK protein levels. FAK protein overexpression in tumors correlated with nodal metastases. Conclusions: These findings suggest an involvement of FAK in the onset and progression of HNSCC and provide an insight into a mechanism of FAK activation alternative to gene amplification.

ONCOLOGIC OUTCOMES OF TRANSORAL LASER SURGERY OF SUPRAGLOTTIC CARCINOMA COMPARED WITH A TRANSCERVICAL APPROACH

To evaluate the oncologic effectiveness of transoral laser surgery of supraglottic cancer, we compared a group of patients treated with laser surgery, with a stage‐matched group treated with a transcervical approach.

Néstor–Guillermo progeria syndrome: A novel premature aging condition with early onset and chronic development caused by BANF1 mutations

Progeria syndromes are rare disorders that involve premature aging. Mutations in BANF1 have been recently reported to cause a new hereditary progeroid syndrome that we now propose to call the Néstor–Guillermo progeria syndrome (NGPS). We describe herein the clinical features of the first two NGPS patients, who phenocopy features of classic progerias (i.e., Hutchinson–Gilford progeria syndrome or mandibuloacral dysplasia), such as aged appearance, growth retardation, decreased subcutaneous fat, thin limbs, and stiff joints. However, these NGPS patients have a distinctive phenotype. In their early adulthood (32 and 24 years of age), they have no signs of cardiovascular impairment, diabetes mellitus, or hypertriglyceridemia. In contrast, they suffer profound skeletal abnormalities that affect their quality of life. The observed differences are of utmost importance to patients and their families and palliation of osseous manifestations is a priority, given their relatively long lifespan. We define NGPS as a chronic progeria because of its slow clinical course and relatively long survival, despite its early onset. Understanding the differences between progeria syndromes might contribute to the development of treatment strategies for common skeletal conditions, as well as aging itself.

Functional outcomes of transoral laser surgery of supraglottic carcinoma compared with a transcervical approach: Transoral Versus Transcervical Supraglottic Laryngectomy

Several functional advantages have been described for the transoral laser supraglottic laryngectomy as compared with open techniques. However, comparative studies have been rarely performed.

Prelamin A causes progeria through cell-extrinsic mechanisms and prevents cancer invasion

Defining the relationship between ageing and cancer is a crucial but challenging task. Mice deficient in Zmpste24, a metalloproteinase mutated in human progeria and involved in nuclear prelamin A maturation, recapitulate multiple features of ageing. However, their short lifespan and serious cell-intrinsic and cell-extrinsic alterations restrict the application and interpretation of carcinogenesis protocols. Here we present Zmpste24 mosaic mice that lack these limitations. Zmpste24 mosaic mice develop normally and keep similar proportions of Zmpste24-deficient (prelamin A accumulating) and Zmpste24-proficient (mature lamin A containing) cells throughout life, revealing that cell-extrinsic mechanisms are preeminent for progeria development. Moreover, prelamin A accumulation does not impair tumour initiation and growth, but it decreases the incidence of infiltrating oral carcinomas. Accordingly, silencing of ZMPSTE24 reduces human cancer cell invasiveness. Our results support the potential of cell-based and systemic therapies for progeria and highlight ZMPSTE24 as a new anticancer target.

Cell-cell adhesion genes CTNNA2 and CTNNA3 are tumour suppressors frequently mutated in laryngeal carcinomas.

Laryngeal squamous cell carcinoma is a frequent and significant cause of morbidity and mortality. Here we explore the biological basis of this aggressive tumour, and identify two cell-cell adhesion genes as recurrently mutated in this malignancy. We first perform exome sequencing of four laryngeal carcinomas and their matched normal tissues. Among the 569 genes found to present somatic mutations, and based on their recurrence or functional relevance in cancer, we select 40 for further validation in 86 additional laryngeal carcinomas. We detect frequent mutations (14 of 90, 15%) in CTNNA2 and CTNNA3-encoding α-catenins. Functional studies reveal an increase in the migration and invasive ability of head and neck squamous cell carcinoma cells producing mutated forms of CTNNA2 and CTNNA3 or in cells where both α-catenins are silenced. Analysis of the clinical relevance of these mutations demonstrates that they are associated with poor prognosis. We conclude that CTNNA2 and CTNNA3 are tumour suppressor genes frequently mutated in laryngeal carcinomas.

Refining the role of pms2 in Lynch syndrome: germline mutational analysis improved by comprehensive assessment of variants

Background and aim The majority of mismatch repair (MMR) gene mutations causing Lynch syndrome (LS) occur either in MLH1 or MSH2. However, the relative contribution of PMS2 is less well defined. The aim of this study was to evaluate the role of PMS2 in LS by assessing the pathogenicity of variants of unknown significance (VUS) detected in the mutational analysis of PMS2 in a series of Spanish patients. Methods From a cohort of 202 LS suspected patients, 13 patients showing loss of PMS2 expression in tumours were screened for germline mutations in PMS2, using a long range PCR based strategy and multiplex ligation dependent probe amplification (MLPA). Pathogenicity assessment of PMS2 VUS was performed evaluating clinicopathological data, frequency in control population and in silico and in vitro analyses at the RNA and protein level. Results Overall 25 different PMS2 DNA variants were detected. Fourteen were classified as polymorphisms. Nine variants were classified as pathogenic: seven alterations based on their molecular nature and two after demonstrating a functional defect (c.538-3C>G affected mRNA processing and c.137G>T impaired MMR activity). The c.1569C>G variant was classified as likely neutral while the c.384G>A remained as a VUS. We have also shown that the polymorphic variant c.59G>A is MMR proficient. Conclusions Pathogenic PMS2 mutations were detected in 69% of patients harbouring LS associated tumours with loss of PMS2 expression. In all, PMS2 mutations account for 6% of the LS cases identified. The comprehensive functional analysis shown here has been useful in the classification of PMS2 VUS and contributes to refining the role of PMS2 in LS.

P53 expression in squamous cell carcinomas of the supraglottic larynx and its lymph node metastases : New results for an old question

Although p53 overexpression is frequent in head and neck squamous cell carcinomas (HNSCCs), controversy remains regarding the prognostic significance of that overexpression. The objective of this study was to investigate the expression pattern and prognostic significance of p53 expression in HNSCC of the same location, treated in the same way, and with long‐term follow‐up.