Distinct Driver Pathway Enrichments and a High Prevalence of TSC2 Mutations in Right Colon Cancer in Chile: A Preliminary Comparative Analysis.

Colorectal cancer (CRC) is the second leading cause of cancer deaths globally. While ethnic differences in driver gene mutations have been documented, the South American population remains understudied at the genomic level, despite facing a rising burden of CRC. We analyzed tumors of 40 Chilean CRC patients (Chp) using next-generation sequencing and compared them to data from mainly Caucasian cohorts (TCGA and MSK-IMPACT). We identified 388 mutations in 96 out of 135 genes, with TP53 (45%), KRAS (30%), PIK3CA (22.5%), ATM (20%), and POLE (20%) being the most frequently mutated. TSC2 mutations were associated with right colon cancer (44.44% in RCRC vs. 6.45% in LCRC, p-value = 0.016), and overall frequency was higher compared to TCGA (p-value = 1.847 × 10-5) and MSK-IMPACT cohorts (p-value = 3.062 × 10-2). Limited sample size restricts definitive conclusions, but our data suggest potential differences in driver mutations for Chilean patients, being that the RTK-RAS oncogenic pathway is less affected and the PI3K pathway is more altered in Chp compared to TCGA (45% vs. 25.56%, respectively). The prevalence of actionable pathways and driver mutations can guide therapeutic choices, but can also impact treatment effectiveness. Thus, these findings warrant further investigation in larger Chilean cohorts to confirm these initial observations. Understanding population-specific driver mutations can guide the development of precision medicine programs for CRC patients.

Classification of patients with metastatic colorectal cancer into consensus molecular subtypes into real-world: A pilot study.

BACKGROUND: Colorectal cancer is a complex disease with high mortality rates. Over time, the treatment of metastatic colorectal cancer (mCRC) has gradually improved due to the development of modern chemotherapy and targeted therapy regimens. However, due to the inherent heterogeneity of this condition, identifying reliable predictive biomarkers for targeted therapies remains challenging. A recent promising classification system-the consensus molecular subtype (CMS) system-offers the potential to categorize mCRC patients based on their unique biological and molecular characteristics. Four distinct CMS categories have been defined: immune (CMS1), canonical (CMS2), metabolic (CMS3), and mesenchymal (CMS4). Nevertheless, there is currently no standardized protocol for accurately classifying patients into CMS categories. To address this challenge, reverse transcription polymerase chain reaction (RT-qPCR) and next-generation genomic sequencing (NGS) techniques may hold promise for precisely classifying mCRC patients into their CMSs. AIM: To investigate if mCRC patients can be classified into CMS categories using a standardized molecular biology workflow. METHODS: This observational study was conducted at the University of Chile Clinical Hospital and included patients with unresectable mCRC who were undergoing systemic treatment with chemotherapy and/or targeted therapy. Molecular biology techniques were employed to analyse primary tumour samples from these patients. RT-qPCR was utilized to assess the expression of genes associated with fibrosis (TGF-ß and ß-catenin) and cell growth pathways (c-MYC). NGS using a 25-gene panel (TumorSec) was performed to identify specific genomic mutations. The patients were then classified into one of the four CMS categories according to the clinical consensus of a Tumour Board. Informed consent was obtained from all the patients prior to their participation in this study. All techniques were conducted at University of Chile. RESULTS: Twenty-six patients were studied with the techniques and then evaluated by the Tumour Board to determine the specific CMS. Among them, 23% (n = 6), 19% (n = 5), 31% (n = 8), and 19% (n = 5) were classified as CMS1, CMS2, CMS3, and CMS4, respectively. Additionally, 8% of patients (n = 2) could not be classified into any of the four CMS categories. The median overall survival of the total sample was 28 mo, and for CMS1, CMS2, CMS3 and CMS4 it was 11, 20, 30 and 45 mo respectively, with no statistically significant differences between groups. CONCLUSION: A molecular biology workflow and clinical consensus analysis can be used to accurately classify mCRC patients. This classification process, which divides patients into the four CMS categories, holds significant potential for improving research strategies and targeted therapies tailored to the specific characteristics of mCRC.

Frequency, Markers and Costs of Secondary Bacterial Infection in Pediatric Dengue.

BACKGROUND: Secondary bacterial infection (SBI) occurs in a proportion of individuals with dengue and results in longer hospitalization, higher mortality, and increased health-related costs. However, the frequency, risk factors and predictive biomarkers of this comorbidity in pediatric dengue is partially known. METHODS: We conducted a retrospective multicenter study in a dengue hyperendemic region of Colombia, analyzing 1597 children from two pediatric cohorts. We included children with confirmed dengue (mild to severe disease) and evaluated the rate of SBI, their clinical characteristics, diagnostic predictors and attention costs. We also assessed the diagnostic performance of plasma interleukin (IL)-6 for detecting SBI in pediatric dengue. RESULTS: The frequency of SBI in children with dengue with warning signs in cohorts 1 and 2 was 2.4% and 7.3%, respectively, and this rate reached 30.7% and 38.2% in children with severe disease. Staphylococcus aureus and Escherichia coli were the more frequent infectious agents. Increased total leukocytes and C-reactive protein levels, as well as high IL-6 at hospital admission, in children <48 months of age were early indications of SBI in dengue. Higher rates of organ dysfunction, the requirement of a longer hospitalization and a 2.3-fold increase in attention costs were observed in SBI. CONCLUSIONS: An important proportion of children with dengue course with SBI and exhibit higher morbidity. Elevated leukocytes, C-reactive protein and IL-6 in young children are early markers of SBI. Physicians should identify children with dengue and risk factors for SBI, microbiologically confirm the bacterial infection, and rationally and timely provide antimicrobial therapy.

Cognitive flexibility and DSM-5 severity criteria for eating disorders: assessing drive for thinness and duration of illness as alternative severity variables.

BACKGROUND: The severity criteria for eating disorders (EDs) proposed in the DSM-5 have been established without sufficient empirical support. Drive for thinness (DT) and duration of illness have been proposed as two alternative severity measures, however their empirical evidence is also limited. To date, no research has assessed the validity of current eating disorder (ED) severity criteria regarding cognitive flexibility factors. Cognitive flexibility is often impaired in EDs, becoming a possible severity symptom. The current study assessed for the first time (1) whether the severity indexes for EDs proposed in the DSM-5 were associated with deficits in cognitive flexibility and, (2) whether drive for thinness and illness duration, acted as an alternative, more meaningful severity indices for deficiencies in cognitive flexibility. METHODS: Participants were 161 patients diagnosed with an ED, who were categorized according to DSM-5 severity categories, DT and duration of illness. Discriminative capacity of each classification was assessed for cognitive flexibility measured by Wisconsin card sorting test (WCST). RESULTS: The findings for the DSM-5 classification comprised: (a) In the anorexia nervosa (AN) group, patients with moderate severity showed better scores in WCST than patients with mild and severe/extreme severity. Also, patients with moderate severity showed lower percentage of cognitive flexibility deficits than the other two severity categories; (b) For the binge spectrum disorders (BSD) group, the patients with mild severity showed a higher percentage of cognitive flexibility deficits than did the moderate and severe/extreme categories. When assessing the alternative severity index of DT, no differences were found in cognitive flexibility in any of the groups. Regarding illness duration, in the AN group the task performance of the patients with longer illness duration was worse than the performance of the short duration group and, in the BSD group, patients with longer duration also showed more deficits in cognitive flexibility than the patients with shorter duration of illness. CONCLUSIONS: Our findings point out the limitations of the DSM-5 severity criteria to categorize cognitive flexibility in EDs and support illness duration as an alternative severity approach for EDs.

Common and differential risk factors behind suicidal behavior in patients with impulsivity-related disorders: The case of bulimic spectrum eating disorders and gambling disorder.

Background and aims: Mental disorders with high levels of impulsivity such as bulimic spectrum eating disorders (BSED) and gambling disorder (GD) are associated with high risk of suicidal behavior. The aim of the present study was to identify the common and differential vulnerability factors behind suicide attempts in a sample of patients with BSED compared to patients with GD. Methods: A total of 6,077 adults who sought treatment and met criteria either for BSED (n = 2,391) or GD (n = 3,686) were assessed at a specialized hospital unit. Personality traits, psychopathological symptomatology, lifetime history of suicide attempts and socio-demographic variables were evaluated. Results: The prevalence of suicide attempts was higher for BSED patients (26.2%) compared to GD patients (7.1%) being anorexia nervosa (Binge/Purge type) and bulimia nervosa the most affected subtypes. In the predictive model, the transdiagnostic vulnerability factors with the highest contribution to the risk of suicidal behavior both in BSED and GD were unemployment, early age of onset of the disorder, worse psychopathological state, and self-transcendence personality trait. However, specific risk factors for suicidal acts were identified in each disorder: longer duration of the disorder, lower education levels and reward dependence were exclusively associated with BSED while female gender, older age, and higher harm avoidance were associated with GD. Discussion: Patients with GD and BSED share certain vulnerability factors although certain factors are exclusive to each disorder. Conclusions: Interventions need to pay special attention to both common and specific vulnerability factors to mitigate the risk of suicidal acts in these disorders.

Routine Use of Biomarkers to Rationalize Antibiotic Use During Febrile Episodes in Pediatric Bone Marrow Transplantation Units.

BACKGROUND: Children frequently develop fever after hematopoietic stem cell transplant (HSCT). Although the etiology of many febrile episodes (FEs) is not an infection, patients often receive broad-spectrum antibiotics in response. METHODS: To improve the judicious use of antibiotics in pediatric HSCT patients, we performed a prospective cohort study of children receiving an HSCT in Clínica Imbanaco (Cali, Colombia) between September 2016 and December 2019. We assessed all FEs occurring during 3 periods (infusion, neutropenic and engraftment). We measured procalcitonin and C-reactive protein (CRP) sequentially during each FE and compared levels among patients with fever due to significant infection (FSI) versus fever not attributable to infection (FNI) in each transplant period. RESULTS: There were 166 FEs in 95 patients. FSI accounted for 12%, 42% and 42% of FE during infusion, neutropenic and engraftment periods, respectively. CRP had better discriminatory capacity for FSI versus FNI in the infusion period [area under the curve (AUC) 0.80 (95% confidence interval [CI], 0.62-0.96) for a CRP level of 50 mg/L]. Neither biomarker performed well in the neutropenic period. During the engraftment period, a CRP of 65 mg/L had an AUC of 0.81 (95% CI, 0.65-0.96), while a procalcitonin level of 0.25 ng/mL had an AUC of 0.83 (95% CI, 0.63-1.0). In contrast to procalcitonin, the CRP's pattern of change throughout the first 3 days of fever in each transplant period was different in FSI compared with FNI. CONCLUSION: Sequential measurement of biomarkers, especially CRP, may allow clinicians to more appropriately manage antibiotic use in pediatric HSCT units.

Validation of an NGS Panel Designed for Detection of Actionable Mutations in Tumors Common in Latin America.

Next-generation sequencing (NGS) is progressively being used in clinical practice. However, several barriers preclude using this technology for precision oncology in most Latin American countries. To overcome some of these barriers, we have designed a 25-gene panel that contains predictive biomarkers for most current and near-future available therapies in Chile and Latin America. Library preparation was optimized to account for low DNA integrity observed in formalin-fixed paraffin-embedded tissue. The workflow includes an automated bioinformatic pipeline that accounts for the underrepresentation of Latin Americans in genome databases. The panel detected small insertions, deletions, and single nucleotide variants down to allelic frequencies of 0.05 with high sensitivity, specificity, and reproducibility. The workflow was validated in 272 clinical samples from several solid tumor types, including gallbladder (GBC). More than 50 biomarkers were detected in these samples, mainly in BRCA1/2, KRAS, and PIK3CA genes. In GBC, biomarkers for PARP, EGFR, PIK3CA, mTOR, and Hedgehog signaling inhibitors were found. Thus, this small NGS panel is an accurate and sensitive method that may constitute a more cost-efficient alternative to multiple non-NGS assays and costly, large NGS panels. This kind of streamlined assay with automated bioinformatics analysis may facilitate the implementation of precision medicine in Latin America.

Same-day SARS-CoV-2 antigen test screening in an indoor mass-gathering live music event: a randomised controlled trial.

BACKGROUND: The banning of mass-gathering indoor events to prevent SARS-CoV-2 spread has had an important effect on local economies. Despite growing evidence on the suitability of antigen-detecting rapid diagnostic tests (Ag-RDT) for mass screening at the event entry, this strategy has not been assessed under controlled conditions. We aimed to assess the effectiveness of a prevention strategy during a live indoor concert. METHODS: We designed a randomised controlled open-label trial to assess the effectiveness of a comprehensive preventive intervention for a mass-gathering indoor event (a live concert) based on systematic same-day screening of attendees with Ag-RDTs, use of facial masks, and adequate air ventilation. The event took place in the Sala Apolo, Barcelona, Spain. Adults aged 18-59 years with a negative result in an Ag-RDT from a nasopharyngeal swab collected immediately before entering the event were randomised 1:1 (block randomisation stratified by age and gender) to either attend the indoor event for 5 hours or go home. Nasopharyngeal specimens used for Ag-RDT screening were analysed by real-time reverse-transcriptase PCR (RT-PCR) and cell culture (Vero E6 cells). 8 days after the event, a nasopharyngeal swab was collected and analysed by Ag-RDT, RT-PCR, and a transcription-mediated amplification test (TMA). The primary outcome was the difference in incidence of RT-PCR-confirmed SARS-CoV-2 infection at 8 days between the control and the intervention groups, assessed in all participants who were randomly assigned, attended the event, and had a valid result for the SARS-CoV-2 test done at follow-up. The trial is registered at ClinicalTrials.gov, NCT04668625. FINDINGS: Participant enrollment took place during the morning of the day of the concert, Dec 12, 2020. Of the 1140 people who responded to the call and were deemed eligible, 1047 were randomly assigned to either enter the music event (experimental group) or continue with normal life (control group). Of the 523 randomly assigned to the experimental group, 465 were included in the analysis of the primary outcome (51 did not enter the event and eight did not take part in the follow-up assessment), and of the 524 randomly assigned to the control group, 495 were included in the final analysis (29 did not take part in the follow-up). At baseline, 15 (3%) of 495 individuals in the control group and 13 (3%) of 465 in the experimental group tested positive on TMA despite a negative Ag-RDT result. The RT-PCR test was positive in one case in each group and cell viral culture was negative in all cases. 8 days after the event, two (<1%) individuals in the control arm had a positive Ag-RDT and PCR result, whereas no Ag-RDT nor RT-PCR positive results were found in the intervention arm. The Bayesian estimate for the incidence between the experimental and control groups was -0·15% (95% CI -0·72 to 0·44). INTERPRETATION: Our study provides preliminary evidence on the safety of indoor mass-gathering events during a COVID-19 outbreak under a comprehensive preventive intervention. The data could help restart cultural activities halted during COVID-19, which might have important sociocultural and economic implications. FUNDING: Primavera Sound Group and the #YoMeCorono Initiative. TRANSLATION: For the Spanish translation of the abstract see Supplementary Materials section.

A comparison of the Grass strobe and new LED photic stimulator for paediatric electroretinogram recordings.

PURPOSE: This study evaluated a new light-emitting diode (LED-S) photic stimulator and compared skin electroretinogram (ERG) responses obtained to those evoked by the Grass Instrument stimulator (GP-S). METHODS: Two sub-studies were combined to evaluate the difference in responses resulting from the LED-S and GP-S stimuli. The first was a photometry study that matched the LED-S stimuli to the GP-S. In the second study, electroretinograms (ERGs) were recorded under scotopic and photopic conditions using stimuli each stimulator. The stimuli were matched photometrically to measurements obtained from the photometer located 30 cm in front of the stimulators. In addition, the ERG responses were recorded from the LED stimulator when photometrically matched to the GP-S blue stimulus presented through a ganzfeld. The amplitudes and time peaks of the resulting ERG a- and b-waves were then measured and compared using paired T-tests. RESULTS: Study 1: The LED-S was matched to the GP-S at various intensity settings measured 30 cm away from the stimulator. Measurement through a ganzfeld full-field stimulator (GFFS) demonstrated that the GP-S had a significant hot spot centrally. Study 2: Photometrically matched ERGs evoked by both stimulators while employing the direct head-on measurements demonstrated multiple similarities. Similarities included component morphology, amplitude and implicit time across the two stimulators, excluding the rod-driven stimulus (GP-S setting employing a blue filter). Differences between the rod-driven ERGs evoked by the GP-S and LED-S while employing head-on photometric measurements were due to the significant difference in intensities between the two stimulators. The GP-S and LED-S evoked similar rod-driven ERG responses when they were matched using the GFFS photometrically matched intensities protocol. CONCLUSION: A hand-held stimulator is essential when recording ERG's in the practice of paediatric visual electrophysiology. The LED-S can match the GP-S stimulus intensities, making it a potential replacement for the GP-S. In addition, the LED-S has uniform intensity across the surface of the device compared to the GP-S, is silent for standard stimuli and can generate prolonged duration stimuli for the recording of on-off ERGs.

HIVconsv Vaccines and Romidepsin in Early-Treated HIV-1-Infected Individuals: Safety, Immunogenicity and Effect on the Viral Reservoir (Study BCN02).

Kick&kill strategies combining drugs aiming to reactivate the viral reservoir with therapeutic vaccines to induce effective cytotoxic immune responses hold potential to achieve a functional cure for HIV-1 infection. Here, we report on an open-label, single-arm, phase I clinical trial, enrolling 15 early-treated HIV-1-infected individuals, testing the combination of the histone deacetylase inhibitor romidepsin as a latency-reversing agent and the MVA.HIVconsv vaccine. Romidepsin treatment resulted in increased histone acetylation, cell-associated HIV-1 RNA, and T-cell activation, which were associated with a marginally significant reduction of the viral reservoir. Vaccinations boosted robust and broad HIVconsv-specific T cells, which were strongly refocused toward conserved regions of the HIV-1 proteome. During a monitored ART interruption phase using plasma viral load over 2,000 copies/ml as a criterium for ART resumption, 23% of individuals showed sustained suppression of viremia up to 32 weeks without evidence for reseeding the viral reservoir. Results from this pilot study show that the combined kick&kill intervention was safe and suggest a role for this strategy in achieving an immune-driven durable viremic control.

Switching from a ritonavir-boosted PI to dolutegravir as an alternative strategy in virologically suppressed HIV-infected individuals.

Background: Switching from PIs to dolutegravir in virologically suppressed HIV-infected individuals has not been assessed. Objectives: The principal aim was to assess the evolution of bone mineral density (BMD) when switching from a ritonavir-boosted PI to dolutegravir in HIV-infected patients with osteopenia or osteoporosis. The secondary objective was to assess the antiviral efficacy and safety of the switch therapy. Methods: This randomized, multicentre study assessed changes in BMD, bone turnover markers, and antiviral efficacy and safety in 73 virologically suppressed patients with osteopenia/osteoporosis taking a ritonavir-boosted PI plus abacavir/lamivudine who were randomized to switch from PI to dolutegravir (DOLU group, n = 37) or continue with a PI (PI group, n = 36). Clinical Trials: NCT02577042. Results: One and three patients from the DOLU and PI groups, respectively, withdrew prematurely (unrelated to treatment). At 48 weeks, 97.3% versus 91.7%, respectively, maintained viral suppression (snapshot analysis, ITT, M = F). No significant differences were seen between the groups in percentage change from baseline to week 48 in femoral ( P = 0.56) and lumbar spine ( P = 0.29) BMD, although lumbar spine BMD improved by 1.43% (-1.36; 2.92) in the DOLU group [0.12% (-2.83; 2.89) in the PI group]. Bone marker values did not vary significantly. At week 48, triglycerides were lower ( P < 0.001) and HDL cholesterol higher ( P = 0.027) in the DOLU group. Conclusions: Dolutegravir + Kivexa ® was safe and well-tolerated in virologically suppressed patients receiving a PI-based regimen. The lipid profile was better, albeit without significant changes in BMD, probably because of the short follow-up.

Total and Envelope Protein-Specific Antibody-Secreting Cell Response in Pediatric Dengue Is Highly Modulated by Age and Subsequent Infections.

The response of antibody-secreting cells (ASC) induced by dengue has only recently started to be characterized. We propose that young age and previous infections could be simple factors that affect this response. Here, we evaluated the primary and secondary responses of circulating ASC in infants (6-12 months old) and children (1-14 years old) infected with dengue showing different degrees of clinical severity. The ASC response was delayed and of lower magnitude in infants, compared with older children. In primary infection (PI), the total and envelope (E) protein-specific IgM ASC were dominant in infants but not in children, and a negative correlation was found between age and the number of IgM ASC (rho = -0.59, P = 0.03). However, infants with plasma dengue-specific IgG detectable in the acute phase developed an intense ASC response largely dominated by IgG and comparable to that of children with secondary infection (SI). IgM and IgG produced by ASC circulating in PI or SI were highly cross-reactive among the four serotypes. Dengue infection caused the disturbance of B cell subsets, particularly a decrease in the relative frequency of naïve B cells. Higher frequencies of total and E protein-specific IgM ASC in the infants and IgG in the children were associated with clinically severe forms of infection. Therefore, the ASC response induced by dengue is highly influenced by the age at which infection occurs and previous immune status, and its magnitude is a relevant element in the clinical outcome. These results are important in the search for correlates of protection and for determining the ideal age for vaccinating against dengue.

Withdrawing inactive NRTIs in HIV-1 subjects with suppressed viraemia: a randomized trial.

BACKGROUND: Extensively pretreated subjects with virological failure (VF) may receive salvage regimens containing NRTIs with only residual or no activity. Once virological suppression is achieved, their contribution remains elusive. METHODS: This was a multicentre, randomized, prospective study. Subjects with at least one prior VF, HIV-1 RNA <50 copies/mL for ≥6 months and receiving a regimen with at least two active drugs (one of them a boosted PI) were randomized 1:1 to stop (experimental arm) or maintain (control arm) NRTIs. EudraCT: 2012-000198-21. RESULTS: Ninety subjects were randomized (experimental, n = 45; and control, n = 45). The mean age was 50 years, 80% were male, the mean CD4+ cell count was 542 cells/mm(3) and the median number of prior VFs was 3. Seventy-four subjects (82%) harboured the mutation M184V/I and the median number of thymidine-associated mutations was 3 (IQR: 0-4). In the experimental arm, thirty-two (71%) subjects removed one NRTI and 13 (29%) subjects removed two. Twenty-two of 45 (49%) discontinued tenofovir disoproxil fumarate. Forty-one of 45 (91.1%, experimental arm) and 44 of 45 (97.8%, control arm) had HIV-1 RNA <50 copies/mL at 48 weeks (difference: -6.7%; 95% CI: -17.4, 4.1). In a post-hoc analysis allowing NRTI reintroduction, efficacy rates were 95.6% and 97.8%, respectively (difference: -2.2%; 95% CI: -7.2, 2.7). Rates of discontinuation at 48 weeks were 2% in both arms. One subject developed a late VF with resistance selection. CONCLUSIONS: In patients receiving a successful multidrug salvage regimen with at least two active drugs (one a boosted PI), the withdrawal of inactive NRTIs was safe, rates of VF were low and drug resistance was uncommon at 48 weeks in this small study. This strategy could potentially prevent long-term toxicities, reduce the number of drugs and reduce costs if non-inferiority was met in a fully powered trial.

Peroxisome proliferators reduce spatial memory impairment, synaptic failure, and neurodegeneration in brains of a double transgenic mice model of Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive deterioration of cognitive abilities, accumulation of the amyloid-ß peptide (Aß), increase of oxidative stress, and synaptic alterations. The scavenging of reactive oxygen species through their matrix enzyme catalase is one of the most recognized functions of peroxisomes. The induction of peroxisome proliferation is attained through different mechanisms by a set of structurally diverse molecules called peroxisome proliferators. In the present work, a double transgenic mouse model of AD that co-expresses a mutant human amyloid-ß protein precursor (AßPPswe) and presenilin 1 without exon 9 (PS1dE9) was utilized in order to assess the effect of peroxisomal proliferation on Aß neurotoxicity in vivo. Mice were tested for spatial memory and their brains analyzed by cytochemical, electrophysiological, and biochemical methods. We report here that peroxisomal proliferation significantly reduces (i) memory impairment, found in this model of AD; (ii) Aß burden and plaque-associated acetylcholinesterase activity; (iii) neuroinflammation, measured by the extent of astrogliosis and microgliosis; and (iv) the decrease in postsynaptic proteins, while promoting synaptic plasticity in the form of long-term potentiation. We concluded that peroxisomal proliferation reduces various AD neuropathological markers and peroxisome proliferators may be considered as potential therapeutic agents against the disease.

Chromosomal instability in mouse embryonic fibroblasts null for the transcriptional co-repressor Ski.

Ski is a transcriptional regulator that has been considered an oncoprotein given its ability to induce oncogenic transformation in avian model systems. However, studies in mouse and in some human tumor cells have also indicated a tumor suppressor activity for this protein. We found that Ski-/- mouse embryo fibroblasts exhibit high levels of genome instability, namely aneuploidy, consistent with a tumor suppressor function for Ski. Time-lapse microscopy revealed lagging chromosomes and chromatin/chromosome bridges as the major cause of micronuclei (MN) formation and the subsequent aneuploidy. Although these cells arrested in mitosis after treatment with spindle disrupting drugs and exhibited a delayed metaphase/anaphase transition, spindle assembly checkpoint (SAC) was not sufficient to prevent chromosome missegregation, consistent with a weakened SAC. Our in vivo analysis also showed dynamic metaphase plate rearrangements with switches in polarity in cells arrested in metaphase. Importantly, after ectopic expression of Ski the cells that displayed this metaphase arrest died directly during metaphase or after aberrant cell division, relating SAC activation and mitotic cell death. This increased susceptibility to undergo mitosis-associated cell death reduced the number of MN-containing cells. The presented data support a new role for Ski in the mitotic process and in maintenance of genetic stability, providing insights into the mechanism of tumor suppression mediated by this protein.

TRPM4 enhances cell proliferation through up-regulation of the ß-catenin signaling pathway.

Altered expression of some members of the TRP ion channel superfamily has been associated with the development of pathologies like cancer. In particular, TRPM4 levels are reportedly elevated in diffuse large B-cell non-Hodgkin lymphoma, prostate, and cervical cancer. However, whether such changes in TRPM4 expression may be relevant to genesis or progression of cancer remains unknown. Here we show that reducing TRPM4 expression decreases proliferation of HeLa cells, a cervical cancer-derived cell line. In this cell line, constitutive TRPM4 silencing promoted GSK-3ß-dependent degradation of ß-catenin and reduced ß-catenin/Tcf/Lef-dependent transcription. Conversely, overexpression of TRPM4 in T-REx 293 cells (a HEK293-derived cell line) increased cell proliferation and ß-catenin levels. Our results identify TRPM4 as an important, unanticipated regulator of the ß-catenin pathway, where aberrant signaling is frequently associated with cancer.

Búsqueda de afecciones genéticas como etiología de déficit intelectual en individuos que asisten a escuelas de educación especial / Genetic screening to determine an etiologic diagnosis in children with mental retardation

Background: Mental retardation or intellectual disability affects 2 percent ofthe general population, but in 60 percent to 70 percent of cases the real cause ofthis retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak aáreas and providing a genetic counseling to the family Aim: To search genetic diseases underíying intellectual disabilities of children attending a special education school. Material and methods: A clinical geneticist performed the history and physical examination in one hundred and three students aged between 5 and 24 years (51 males). A blood sample was obtained in 92 of them for a genetic screening that included a standard karyotype, fragile X molecular genetic testing and search for inborn errors of metabolism by tándem mass spectrometry. Results: This approach yielded an etiological diagnosis in as much as 29 patients. Three percent of them had a fragile X syndrome. Inborn errors of metabolism were not detected. Conclusions: This type of screening should be done always in children with intellectual disability to establish an etiological diagnosis.

[Genetic screening to determine an etiologic diagnosis in children with mental retardation]. / Búsqueda de afecciones genéticas como etiología de déficit intelectual en individuos que asisten a escuelas de educación especial.

BACKGROUND: Mental retardation or intellectual disability affects 2% of the general population, but in 60% to 70% of cases the real cause of this retardation is not known. An early etiologic diagnosis of intellectual disability can lead to opportunities for improved educational interventions, reinforcing weak areas and providing a genetic counseling to the family. AIM: To search genetic diseases underlying intellectual disabilities of children attending a special education school. MATERIAL AND METHODS: A clinical geneticist performed the history and physical examination in one hundred and three students aged between 5 and 24 years (51 males). A blood sample was obtained in 92 of them for a genetic screening that included a standard karyotype, fragile X molecular genetic testing and search for inborn errors of metabolism by tandem mass spectrometry. RESULTS: This approach yielded an etiological diagnosis in as much as 29 patients. Three percent of them had a fragile X syndrome. Inborn errors of metabolism were not detected. CONCLUSIONS: This type of screening should be done always in children with intellectual disability to establish an etiological diagnosis.

Diagnóstico citogenético-molecular del síndrome Xq frágil / Diagnostic testing in fragile X syndrome

El síndrome Xq frágil (SXF) es una causa frecuente de retraso mental (RM); se estima que uno de cada 4.000 varones y una década 6.000 mujeres lo presentan. Clínicamente los individuos afectados se caracterizan por presentar déficit intelectual y cognitivo, déficit de lenguaje, macroorquidismo, fascie alargada y orejas prominentes, entre otras dismorfias faciales. A nivel molecular es posible distinguir fundamentalmente dos tipos de alelos mutados: premutacion y mutación completa, las cuales corresponden a amplificación del trinucleótido CGG localizado en el primer exón del gen FMR1; las premutaciones presentan entre 52 y 200 repetidos y las mutaciones completas sobre 200 CGG, con hipermetilación de la región promotora del gen FMR1 e inhibición de la expresión de la proteína FMRP, causante del RM y dismorfias características de este síndrome. Desde que se identifico la mutación en 1991, la pesquisa de pacientes afectados se inicia por el examen clínico y luego el análisis citogenetico clásico y el test de screening basado en PCR para individuos varones y análisis molecular directo del gen FMR 1 por Southern Blot con la sonda Stb 12.3 para pacientes mujeres; los varones que presentan un PCR alterado deben ser confirmados por Southern Blot. El PCR debe ser usado como método de screening solo en varones con RM, sin historia familiar; es un sensible, rápido, de bajo costo y permite determinar el numero de repetidos CGG. Proponemos el uso conjunto de estos métodos para optimizar el estudio molecular directo del gen FMR1 y establecer un protocolo mas eficiente en la pesquisa de afectados, el estudio de familiares a riesgo y el consejo genético adecuado.