Integrated miRNA-mRNA Analysis Reveals Critical miRNAs and Targets in Diet-Induced Obesity-Related Glomerulopathy.

This study aimed to investigate obesity-related glomerulopathy (ORG) at cellular, structural, and transcriptomic levels. Thirty Wistar rats were randomized into two groups: 15 rats were fed with a standard diet (SD-rats), and 15 rats were fed with a high-fat diet (HFD-rats). After 10 weeks, the weight, kidney function, histological features, and transcriptomic changes were assessed. HFD-rats gained significantly more weight (55.8% vs. 29.2%; p < 0.001) and albuminuria (10,384.04 ng/mL vs. 5845.45 ng/mL; p < 0.001) compared to SD-rats. HFD-rats exhibited early stages of ORG, with predominant mesangial matrix increase and podocyte hypertrophy (PH). These lesions correlated with differentially expressed (DE) genes and miRNAs. Functional analysis showed that miR-205, which was DE in both the kidneys and urine of HFD-rats, negatively regulated the PTEN gene, promoting lipid endocytosis in podocytes. The downregulation of PTEN was proved through a higher PTEN/nephrin ratio in the SD-rats and the presence of lipid vacuoles in HFD-podocytes. This study has found a specific targetome of miRNAs and gene expression in early stages of ORG. Also, it emphasizes the potential value of miR-205 as a urinary biomarker for detecting podocyte injury in ORG, offering a tool for early diagnosis, and opening new avenues for future therapeutic research of obesity-related glomerulopathy.

Sexual dysfunction in patients with cancer, a challenge in oncology practice: results of the CLARIFY project.

BACKGROUND: Sexual dysfunction (SD) associated with oncological treatment is a common and understudied disorder. Our aim was to characterize SD in a cohort of Spanish patients. METHODS: Analytic observational study in patients included in the CLARIFY H2020 project at the Hospital Universitario Puerta de Hierro. Clinical variables and validated measures of sexual function were collected from October 2020 to May 2022. Frequency and quality of sexual activity were assessed. Descriptive, trend associations, and logistic regression analyses were performed. RESULTS: A total of 383 patients were included: breast cancer 68.14% (261), lung cancer 26.37% (101), and lymphoma 5.50% (21). Mean age was 56.5 years (range 33-88). 19.58% (75) were men and 80.42% (308) were women. 69% and 31% of men and women, respectively, reported being sexually active. The absolute frequency of overall sexual dissatisfaction was 76% in women and 24% in men. Women with breast cancer were most likely to have severe sexual dysfunction. Those with early disease had resolved complaints after 5 years. In multinomial logistic regression, significant associations were found in women with metastatic breast cancer and severe disorders of arousal (p 0.000), lubrication (p 0.002), orgasm (p 0.000), as well as dissatisfaction with sexual performance (p 0.000) and global sexual dissatisfaction (p 0.000). Women with lung cancer have severe arousal dysfunction (p 0.016) and global sexual dissatisfaction (p 0.044). CONCLUSIONS: Our population has a high prevalence of SD, which supports the need to increase awareness of this disorder among the medical oncology team and the importance of including sexual health assessment in oncological patient follow-up.

NLRP3 inflammasome activation and symptom burden in KRAS-mutated CMML patients is reverted by IL-1 blocking therapy.

Chronic myelomonocytic leukemia (CMML) is frequently associated with mutations in the rat sarcoma gene (RAS), leading to worse prognosis. RAS mutations result in active RAS-GTP proteins, favoring myeloid cell proliferation and survival and inducing the NLRP3 inflammasome together with the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), which promote caspase-1 activation and interleukin (IL)-1ß release. Here, we report, in a cohort of CMML patients with mutations in KRAS, a constitutive activation of the NLRP3 inflammasome in monocytes, evidenced by ASC oligomerization and IL-1ß release, as well as a specific inflammatory cytokine signature. Treatment of a CMML patient with a KRASG12D mutation using the IL-1 receptor blocker anakinra inhibits NLRP3 inflammasome activation, reduces monocyte count, and improves the patient's clinical status, enabling a stem cell transplant. This reveals a basal inflammasome activation in RAS-mutated CMML patients and suggests potential therapeutic applications of NLRP3 and IL-1 blockers.

Etiologia e fisiopatologia da fibromialgia / Etiology and pathophysiology of fibromyalgia

A fibromialgia é uma condição crônica de etiologia desconhecida e desvinculada de marcadores laboratoriais específicos para diagnóstico, devido à pobre caracterização da etiopatogenia. Em geral, as alterações comuns à fibromialgia também são observadas em outras condições de dor crônica, tornando a patogênese controversa entre diferentes condições patológicas. A etiologia desconhecida dificulta o diagnóstico e, consequentemente, repercute em um tratamento não tão eficaz de pacientes com fibromialgia. A restauração de desordens sistêmicas confere amplo espectro de possibilidades terapêuticas com potencial de orientar profissionais a estabelecer metas e métodos de avaliação. Diante disso, essa revisão narrativa se volta para debater hipóteses etiológicas e fisiopatológicas no desenvolvimento da fibromialgia.

Fibromyalgia is a chronic condition of unknown etiology unrelated to specific laboratory markers for diagnosis because of poor etiopathogenesis. In general, the changes common to fibromyalgia are also seen in other chronic pain conditions, making the pathogenesis controversial among different pathological conditions. The unknown etiology makes the diagnosis difficult and consequently has repercussions on a not so effective treatment of patients with fibromyalgia. The restoration of systemic disorders provides a wide spectrum of therapeutic possibilities with the potential to guide professionals in establishing goals and evaluation methods. Therefore, this narrative review discusses the etiological and pathophysiological hypotheses involved in the development of fibromyalgia.

Telomerase Upregulation Induces Progression of Mouse BrafV600E-Driven Thyroid Cancers and Triggers Nontelomeric Effects.

Mutations in the promoter of the telomerase reverse transcriptase (TERT) gene are the paradigm of a cross-cancer alteration in a noncoding region. TERT promoter mutations (TPM) are biomarkers of poor prognosis in cancer, including thyroid tumors. TPMs enhance TERT transcription, which is otherwise silenced in adult tissues, thus reactivating a bona fide oncoprotein. To study TERT deregulation and its downstream consequences, we generated a Tert mutant promoter mouse model via CRISPR/Cas9 engineering of the murine equivalent locus (Tert-123C>T) and crossed it with thyroid-specific BrafV600E-mutant mice. We also employed an alternative model of Tert overexpression (K5-Tert). Whereas all BrafV600E animals developed well-differentiated papillary thyroid tumors, 29% and 36% of BrafV600E+Tert-123C>T and BrafV600E+K5-Tert mice progressed to poorly differentiated cancers at week 20, respectively. Tert-upregulated tumors showed increased mitosis and necrosis in areas of solid growth, and older animals displayed anaplastic-like features, that is, spindle cells and macrophage infiltration. Murine TPM increased Tert transcription in vitro and in vivo, but temporal and intratumoral heterogeneity was observed. RNA-sequencing of thyroid tumor cells showed that processes other than the canonical Tert-mediated telomere maintenance role operate in these specimens. Pathway analysis showed that MAPK and PI3K/AKT signaling, as well as processes not previously associated with this tumor etiology, involving cytokine, and chemokine signaling, were overactivated. These models constitute useful preclinical tools to understand the cell-autonomous and microenvironment-related consequences of Tert-mediated progression in advanced thyroid cancers and other aggressive tumors carrying TPMs. IMPLICATIONS: Telomerase-driven cancer progression activates pathways that can be dissected and perhaps therapeutically exploited.

Pre- and Post-Neoadjuvant Clinicopathological Parameters Can Help in the Prognosis and the Prediction of Response in HER2+ and Triple Negative Breast Cancer.

Neoadjuvant treatment (NAT) is one of the most widely used options for HER2+ and triple negative (TN) early breast cancer (BC). Since around half of the patients treated with NAT do not achieve a pathologically complete response (pCR), biomarkers to predict resistance are urgently needed. The correlation of clinicopathological factors with pCR was studied in 150 patients (HER2 = 81; TN = 69) and pre- and post-NAT differences in tumour biomarkers were compared. Low estrogen receptor (ER) expression, high tumour-infiltrating lymphocytes (TILs) and low cT-stage were associated with pCR in HER2+ tumours (p = 0.022; p = 0.032 and p = 0.005, respectively). Furthermore, ER expression was also associated with residual cancer burden (RCB; p = 0.046) in the HER2+ subtype. Similarly, pre-NAT, low progesterone receptor expression (PR; 1-10%) was associated with higher RCB (p < 0.001) in TN tumours. Only clinical and pathological T-stage (cpT-stage) had prognostic capacity in HER2+ tumours, whereas pre-NAT cpT-stage and post-NAT TILs had this capacity for the prognosis of TN tumours. We conclude that ER and PR expression may help predict response to NAT in HER2 and TN BC and should be taken into account in residual tumours. Also, changes observed in the phenotype after NAT suggest the need to reevaluate biomarkers in surviving residual tumour cells.

Short telomeres in alveolar type II cells associate with lung fibrosis in post COVID-19 patients with cancer.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) pandemic. The severity of COVID-19 increases with each decade of life, a phenomenon that suggest that organismal aging contributes to the fatality of the disease. In this regard, we and others have previously shown that COVID-19 severity correlates with shorter telomeres, a molecular determinant of aging, in patient's leukocytes. Lung injury is a predominant feature of acute SARS-CoV-2 infection that can further progress to lung fibrosis in post-COVID-19 patients. Short or dysfunctional telomeres in Alveolar type II (ATII) cells are sufficient to induce pulmonary fibrosis in mouse and humans. Here, we analyze telomere length and the histopathology of lung biopsies from a cohort of alive post-COVID-19 patients and a cohort of age-matched controls with lung cancer. We found loss of ATII cellularity and shorter telomeres in ATII cells concomitant with a marked increase in fibrotic lung parenchyma remodeling in post- COVID-19 patients compared to controls. These findings reveal a link between presence of short telomeres in ATII cells and long-term lung fibrosis sequel in Post-COVID-19 patients.

Telomerase deficiency and dysfunctional telomeres in the lung tumor microenvironment impair tumor progression in NSCLC mouse models and patient-derived xenografts.

Non-small cell lung cancer (NSCLC) is a leading cause of cancer death. Tumor progression depends on interactions of cancer cells with the tumor microenvironment. Here, we find increased copy number and mRNA expression of the catalytic subunit of telomerase, TERT, in tumors from NSCLC patients, contributing to a lower survival. Moreover, TERT expression in NSCLC patients from the TCGA cohort is mainly associated to the reduced infiltration of CD8+ T lymphocytes, as well as to increased infiltration of myeloid-derived suppressor cells (MDSCs). We also show that TERT deficiency and dysfunctional telomeres induced by 6-thio-dG treatment in mice reduced lung tumor implantation and vascularization, increased DNA damage response, cell cycle arrest and apoptosis, as well as reduced proliferation, inflammation, lung tumor immunosupression and invasion upon induction of a Lewis lung carcinoma (LLC). Furthermore, 6-thio-dG-treated human NSCLC xenografts exhibited increased telomere damage, cell cycle arrest and apoptosis, as well as reduced proliferation, resulting in a reduced tumor growth. Our results show that targeting telomeres might be an effective therapeutic strategy in NSCLC.

Penfigoide ampolloso de origen idiopático

Introducción: El penfigoide ampolloso es una dermatosis vesicular ampollosa autoinmunitaria subepidérmica, asociada a la formación de autoanticuerpos que reconocen autoantígenos en la zona de la membrana basal. El tratamiento inmunomodulador con corticoides es la primera línea en el control de la enfermedad. Objetivo: Presentar el caso clínico de un paciente con diagnóstico de penfigoide ampolloso de origen idiopático. Caso clínico: Paciente masculino de 81 años con lesiones ampollosas dolorosas a la palpación de contenido serohemático, tamaño variado, bordes regulares y base eritematosa a nivel generalizado. La evaluación inicial sugiere diagnóstico de penfigoide ampolloso e infección bacteriana activa de las lesiones en la piel. Se solicitan exámenes de laboratorio e imágenes diagnósticas, se descartan etiologías infecciosas, autoinmunes o neoplásicas asociadas, se inicia tratamiento con corticosteroides intravenosos con adecuada evolución clínica. Finalmente, no se identifican enfermedades asociadas a las lesiones ampollosas del paciente. Conclusión: El penfigoide ampolloso es una entidad poco frecuente, con una elevada tasa de mortalidad si se realiza un diagnóstico y tratamiento tardío. Reconocer las principales manifestaciones y variantes clínicas de esta enfermedad permite un oportuno enfoque diagnóstico y terapéutico, este último basado en el control de la respuesta inflamatoria contra la piel y otros órganos.

Introduction: Bullous pemphigoid is a subepidermal autoimmune bullous vesicular dermatosis associated with the formation of autoantibodies that confirm autoantigens in the basement membrane area. Immunomodulatory treatment with corticosteroids is the first line in the control of the disease. Objective: To present the clinical case of a patient diagnosed with a bullous pemphigoid of idiopathic origin. Clinical case: 81-year-old male patient with blistering lesions that are painful on palpation with serohematic content, varied in size, regular borders and a generalized erythematous base; that the initial evaluation suggests a diagnosis of bullous pemphigoid and active bacterial infection of the skin. Laboratory tests and diagnostic images are requested, infectious, autoimmune or associated neoplastic etiologies are ruled out, treatment with intravenous corticosteroids is started with adequate clinical evolution. Finally, no diseases associated with the patient's blistering lesions were identified. Conclusion: Bullous pemphigoid is a rare entity, with a high mortality rate if a late diagnosis and treatment is performed. Recognizing the main manifestations and clinical variants of this disease allows for a timely diagnostic and therapeutic approach, the latter based on the control of the inflammatory response against the skin and other organs.

Switch to ocrelizumab in MS patients treated with natalizumab in extended interval dosing at high risk of PML: A 96-week follow-up pilot study.

We aimed to assess the long-term safety and effectiveness of ocrelizumab in a cohort of patients with multiple sclerosis (MS) at high risk of progressive multifocal leukoencephalopathy (PML), previously treated with natalizumab in extending interval dosing (EID), who switched to ocrelizumab and to compare them with patients who continued EID-natalizumab. Thirty MS patients previously treated with natalizumab in EID (every 8 weeks) were included in this observational retrospective cohort study. Among them, 17 patients were switched to ocrelizumab and 13 continued with EID-natalizumab. Except for the John Cunningham virus (JCV) index, no significant differences were detected between both groups. Main outcome measures included: annualized relapse rate (ARR), radiological activity, disability progression, and the NEDA-3 index. Patients were followed for 96 weeks. The median washout period in ocrelizumab-switchers was 6 weeks. Among them, AAR and radiological activity during follow-up were 0.03, without significant differences in comparison with the previous period on natalizumab-EID. The comparison between ocrelizumab-switchers and patients continuing on EID-natalizumab showed no significant differences in AAR, radiological activity, or disability progression. However, the proportion of patients maintaining a NEDA-3 status in week 96 was slightly superior among ocrelizumab-switchers (94 vs 69%). No serious adverse events were observed in any group. In conclusion, switching from EID-natalizumab to ocrelizumab can be considered as a therapeutic option, particularly in patients with MS at high risk of PML, to mitigate the risks of both PML and disease reactivation.

CNL and aCML should be considered as a single entity based on molecular profiles and outcomes.

Chronic neutrophilic leukemia (CNL) and atypical chronic myeloid leukemia (aCML) are rare myeloid disorders that are challenging with regard to diagnosis and clinical management. To study the similarities and differences between these disorders, we undertook a multicenter international study of one of the largest case series (CNL, n = 24; aCML, n = 37 cases, respectively), focusing on the clinical and mutational profiles (n = 53 with molecular data) of these diseases. We found no differences in clinical presentations or outcomes of both entities. As previously described, both CNL and aCML share a complex mutational profile with mutations in genes involved in epigenetic regulation, splicing, and signaling pathways. Apart from CSF3R, only EZH2 and TET2 were differentially mutated between them. The molecular profiles support the notion of CNL and aCML being a continuum of the same disease that may fit best within the myelodysplastic/myeloproliferative neoplasms. We identified 4 high-risk mutated genes, specifically CEBPA (ß = 2.26, hazard ratio [HR] = 9.54, P = .003), EZH2 (ß = 1.12, HR = 3.062, P = .009), NRAS (ß = 1.29, HR = 3.63, P = .048), and U2AF1 (ß = 1.75, HR = 5.74, P = .013) using multivariate analysis. Our findings underscore the relevance of molecular-risk classification in CNL/aCML as well as the importance of CSF3R mutations in these diseases.

Treatment of symptomatic macromastia in a breast unit. Outcomes analysis of breast reduction using BREAST-Q.

INTRODUCTION: The BREAST-Q (breast reduction module) is a specific and validated questionnaire to evaluate breast reduction in the treatment of symptomatic macromastia, offering information on their quality of life and degree of satisfaction. METHODS: Prospective study of a cohort of 34 patients treated by bilateral breast reduction in a breast unit in 2017-2020 surveyed with the Spanish version of BREAST-Q version 2. The statistical study to assess the effect of reduction, changes from the pre to postoperative scores of the domains were performed using the Wilcoxon signed rank test. Statistical significance was determined with p values ​​<0.05. RESULTS: The mean time elapsed from surgery to the postoperative survey was 16 (SD 9) months. Post-surgical complications or sequelae occurred in 14 (42%) patients with 23 events. The preoperative scores, median and interquartile range, in satisfaction with the breasts (28, 26), psychological (33, 14), physical (42, 19) and sexual (34, 14) well-being improved in the postoperative survey to (82, 15), (81.29), (82, 30) and (90, 38), respectively. These changes were statistically significant, p < 0.001. CONCLUSIONS: The first application of the BREAST-Q in its version in Spanish for Spanish women in patients with symptomatic macromastia treated surgically in a breast unit shows that breast reduction improves the quality of life of patients and that they are very satisfied with the outcome of the surgery and its surgeon, although the information received should clearly be improved.

BRAF activation by metabolic stress promotes glycolysis sensitizing NRASQ61-mutated melanomas to targeted therapy.

NRAS-mutated melanoma lacks a specific line of treatment. Metabolic reprogramming is considered a novel target to control cancer; however, NRAS-oncogene contribution to this cancer hallmark is mostly unknown. Here, we show that NRASQ61-mutated melanomas specific metabolic settings mediate cell sensitivity to sorafenib upon metabolic stress. Mechanistically, these cells are dependent on glucose metabolism, in which glucose deprivation promotes a switch from CRAF to BRAF signaling. This scenario contributes to cell survival and sustains glucose metabolism through BRAF-mediated phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase-2/3 (PFKFB2/PFKFB3). In turn, this favors the allosteric activation of phosphofructokinase-1 (PFK1), generating a feedback loop that couples glycolytic flux and the RAS signaling pathway. An in vivo treatment of NRASQ61 mutant melanomas, including patient-derived xenografts, with 2-deoxy-D-glucose (2-DG) and sorafenib effectively inhibits tumor growth. Thus, we provide evidence for NRAS-oncogene contributions to metabolic rewiring and a proof-of-principle for the treatment of NRASQ61-mutated melanoma combining metabolic stress (glycolysis inhibitors) and previously approved drugs, such as sorafenib.

Quality of life in cancer survivorship: Sociodemographic and disease-related moderators.

RATIONALE: To identify high-risk survivors in order to provide appropriate care. PURPOSE: To analyse the quality of life (QOL) of cancer survivors using an instrument designed specifically for this population and considering different sociodemographic and disease-related characteristics as possible modulating variables. METHODS: The Quality of Life in Adult Cancer Survivors (QLACS) was filled out by a large and heterogeneous sample of disease-free post-treatment Spanish cancer survivors (N = 1862). RESULTS: QLACS scores were comparable to those obtained in other studies and indicative of worse QOL as a function of shorter elapsed time since the end of primary treatment. The best QOL was shown by prostate, and the worst by hematologic cancer survivors. Both systemic treatments (chemotherapy and hormone therapy) and the combination of radiotherapy and chemotherapy were associated with worse QOL. Likewise, younger age, female sex, unemployment status and not having a stable partner were associated with worse QOL. CONCLUSION: Greater understanding of the QOL experienced by the already large and continuously growing population of cancer survivors is relevant for guiding both clinical practice and health policy. In addition, knowing the risk factors associated with worse QOL facilitates the development of targeted prevention programmes for those survivors who need it the most.

Melatonin drives apoptosis in head and neck cancer by increasing mitochondrial ROS generated via reverse electron transport.

The oncostatic effects of melatonin correlate with increased reactive oxygen species (ROS) levels, but how melatonin induces this ROS generation is unknown. In the present study, we aimed to elucidate the two seemingly opposing actions of melatonin regarding its relationship with free radicals. We analyzed the effects of melatonin on head and neck squamous cell carcinoma cell lines (Cal-27 and SCC-9), which were treated with 0.5 or 1 mM melatonin. We further examined the potential effects of melatonin to induce ROS and apoptosis in Cal-27 xenograft mice. Here we report that melatonin mediates apoptosis in head and neck cancer by driving mitochondrial reverse electron transport (RET) to induce ROS production. Melatonin-induced changes in tumoral metabolism led to increased mitochondrial activity, which, in turn, induced ROS-dependent mitochondrial uncoupling. Interestingly, mitochondrial complex inhibitors, including rotenone, abolished the ROS elevation indicating that melatonin increased ROS generation via RET. Melatonin also increased membrane potential and CoQ10 H2 /CoQ10 ratio to elevate mitochondrial ROS production, which are essential conditions for RET. We found that genetic manipulation of cancer cells with alternative oxidase, which transfers electrons from QH2 to oxygen, inhibited melatonin-induced ROS generation, and apoptosis. RET restored the melatonin-induced oncostatic effect, highlighting the importance of RET as the site of ROS production. These results illustrate that RET and ROS production are crucial factors in melatonin's effects in cancer cells and establish the dual effect of melatonin in protecting normal cells and inducing apoptosis in cancer cells.

Results of a worldwide survey on the currently used histopathological diagnostic criteria for invasive lobular breast cancer.

Invasive lobular carcinoma (ILC) represents the second most common subtype of breast cancer (BC), accounting for up to 15% of all invasive BC. Loss of cell adhesion due to functional inactivation of E-cadherin is the hallmark of ILC. Although the current world health organization (WHO) classification for diagnosing ILC requires the recognition of the dispersed or linear non-cohesive growth pattern, it is not mandatory to demonstrate E-cadherin loss by immunohistochemistry (IHC). Recent results of central pathology review of two large randomized clinical trials have demonstrated relative overdiagnosis of ILC, as only ~60% of the locally diagnosed ILCs were confirmed by central pathology. To understand the possible underlying reasons of this discrepancy, we undertook a worldwide survey on the current practice of diagnosing BC as ILC. A survey was drafted by a panel of pathologists and researchers from the European lobular breast cancer consortium (ELBCC) using the online tool SurveyMonkey®. Various parameters such as indications for IHC staining, IHC clones, and IHC staining procedures were questioned. Finally, systematic reporting of non-classical ILC variants were also interrogated. This survey was sent out to pathologists worldwide and circulated from December 14, 2020 until July, 1 2021. The results demonstrate that approximately half of the institutions use E-cadherin expression loss by IHC as an ancillary test to diagnose ILC and that there is a great variability in immunostaining protocols. This might cause different staining results and discordant interpretations. As ILC-specific therapeutic and diagnostic avenues are currently explored in the context of clinical trials, it is of importance to improve standardization of histopathologic diagnosis of ILC diagnosis.

Comprehensive molecular analysis of immortalization hallmarks in thyroid cancer reveals new prognostic markers.

BACKGROUND: Comprehensive molecular studies on tumours are needed to delineate immortalization process steps and identify sensitive prognostic biomarkers in thyroid cancer. METHODS AND RESULTS: In this study, we extensively characterize telomere-related alterations in a series of 106 thyroid tumours with heterogeneous clinical outcomes. Using a custom-designed RNA-seq panel, we identified five telomerase holoenzyme-complex genes upregulated in clinically aggressive tumours compared to tumours from long-term disease-free patients, being TERT and TERC denoted as independent prognostic markers by multivariate regression model analysis. Characterization of alterations related to TERT re-expression revealed that promoter mutations, methylation and/or copy gains exclusively co-occurred in clinically aggressive tumours. Quantitative-FISH (fluorescence in situ hybridization) analysis of telomere lengths showed a significant shortening in these carcinomas, which matched with a high proliferative rate measured by Ki-67 immunohistochemistry. RNA-seq data analysis indicated that short-telomere tumours exhibit an increased transcriptional activity in the 5-Mb-subtelomeric regions, site of several telomerase-complex genes. Gene upregulation enrichment was significant for specific chromosome-ends such as the 5p, where TERT is located. Co-FISH analysis of 5p-end and TERT loci showed a more relaxed chromatin configuration in short telomere-length tumours compared to normal telomere-length tumours. CONCLUSIONS: Overall, our findings support that telomere shortening leads to a 5p subtelomeric region reorganization, facilitating the transcription and accumulation of alterations at TERT-locus.

A mouse model for Li-Fraumeni-Like Syndrome with cardiac angiosarcomas associated to POT1 mutations.

The shelterin protein POT1 has been found mutated in many different familial and sporadic cancers, however, no mouse models to understand the pathobiology of these mutations have been developed so far. To address the molecular mechanisms underlying the tumorigenic effects of POT1 mutant proteins in humans, we have generated a mouse model for the human POT1R117C mutation found in Li-Fraumeni-Like families with cases of cardiac angiosarcoma by introducing this mutation in the Pot1a endogenous locus, knock-in for Pot1aR117C. We find here that both mouse embryonic fibroblasts (MEFs) and tissues from Pot1a+/ki mice show longer telomeres than wild-type controls. Longer telomeres in Pot1a+/ki MEFs are dependent on telomerase activity as they are not found in double mutant Pot1a+/ki Tert-/- telomerase-deficient MEFs. By using complementation assays we further show that POT1a pR117C exerts dominant-negative effects at telomeres. As in human Li-Fraumeni patients, heterozygous Pot1a+/ki mice spontaneously develop a high incidence of angiosarcomas, including cardiac angiosarcomas, and this is associated to the presence of abnormally long telomeres in endothelial cells as well as in the tumors. The Pot1a+/R117C mouse model constitutes a useful tool to understand human cancers initiated by POT1 mutations.