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ADAR1 Regulates Alternative Splicing Through an RNA Editing-Independent Mechanism
(MDPI AG, 2026-04-29)
Eduardo A. Sagredo
;
Victor Karlström
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Alejandro Blanco
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Paloma Moraga
;
Matias Vergara
<jats:p>Dysregulation of the RNA-editing enzyme ADAR1 is associated with human diseases, including cancer, but its RNA-editing-independent roles in alternative splicing remain largely unexplored. Comprehending these molecular mechanisms is paramount, as they may unveil novel therapeutic targets. This study elucidates how the ADAR1p110 isoform influences alternative splicing independently of its canonical editing activity. Employing RNA-sequencing, proteomic analysis of ADAR1p110 interactors, and functional assays with wild-type and mutant ADAR1 in diverse human cell lines (including cancer models), we investigated its impact on the splicing landscape. Our findings indicate that ADAR1p110 interacts with pivotal spliceosome components and auxiliary splicing regulators. Notably, ADAR1 extensively modulates alternative-splicing events, with most of these alterations occurring independently of its RNA-editing activity and often its RNA-binding capacity. Furthermore, ADAR1 alters the isoform expression of other splicing factors (e.g., ACIN1), suggesting an indirect regulatory mechanism. Importantly, this splicing reprogramming affects genes that govern therapeutic response, positioning the ADAR-splicing axis as a potential driver of drug resistance. By revealing this predominantly editing-independent mechanism, we expand the understanding of ADAR1’s non-canonical functions and identify a new avenue for therapeutic intervention in cancer.</jats:p>
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Integration of RNA Editing into Multiomics Machine Learning Models for Predicting Drug Responses in Breast Cancer Patients
(MDPI AG, 2026-03-14)
Yanara A. Bernal
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Alejandro Blanco
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OROSTICA TAPIA, KAREN YASMINE
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DELGADO BECERRA, OROZIMBA IRIS
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ARMISEN YAÑEZ, RICARDO AMADO
Background: The integration of multi-omics data, such as genomics and transcriptomics, into artificial intelligence models has advanced precision medicine. However, their clinical applicability remains limited due to model complexity. We integrated DNA mutation, RNA expression, and A>I(G) RNA editing data to develop a predictive model for drug response in breast cancer. Methods: We analyzed 104 patients from the Breast Cancer Genome-Guided Therapy Study (ClinicalTrials.gov: NCT02022202). Clinical variables, gene expression, tumor and germline DNA variants, and RNA editing features were integrated into machine learning models to predict therapy response. Generalized linear models (GLM), random forest (RF), and support vector machines (SVM) were trained and evaluated across multiple random 70/30 train-test splits. Feature selection was performed exclusively within the training set using LASSO regularization. Model performance was assessed using the F1-score on independent test sets. The additive effect of RNA editing was evaluated using paired comparisons across identical train/test splits. Results: We characterized the cohort using clinical, mutational, transcriptomic, and RNA editing profiles in 69 non-responders and 35 responders. Across repeated splits, adding RNA editing frequently maintained or modestly improved predictive performance, particularly in expression-based models, with paired analyses showing a statistically significant increase in F1-score. Conclusions: RNA editing represents a complementary molecular layer that can enhance multi-omic models for therapy response prediction in breast cancer, supporting further investigation of epitranscriptomic features in precision oncology.
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Abstract 6440: Effects of cumulative tobacco exposure on lung cancer genomic profiles in Latin Americans
(American Association for Cancer Research (AACR), 2026-04-03)
Javiera Garrido
;
Evelin González
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Alejandro Blanco
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Gonzalo Sepúlveda-Hermosilla
;
Matias Freire
<jats:title>Abstract</jats:title> <jats:sec> <jats:title>Motivation:</jats:title> <jats:p>Tobacco exposure is a major determinant of tumor genomic landscapes in non-small cell lung cancer (NSCLC). Two of the most clinically relevant actionable genes in lung cancer, EGFR and KRAS, show opposite patterns, with smokers exhibiting a higher prevalence of alterations in KRAS and never-smokers in EGFR. Yet, the dynamic and evolution of genomic changes as a function of cumulative tobacco exposure has received limited attention. Here, we examine how tumor genomic profiles vary according to smoking intensity, duration, and time since cessation (TSC). Our study focuses on an underrepresented population of Latin American patients, where additional research is needed to better characterize tumor heterogeneity.</jats:p> </jats:sec> <jats:sec> <jats:title>Methodology:</jats:title> <jats:p>The population was obtained from the protocol Characterization and Validation of Molecular Diagnostic Technologies for Lung Cancer Patients from Chile, Brazil, and Peru. Participant recruitment was between July 2015 and October 2018 across 37 different centers. Primary or metastatic NSCLC specimens were analyzed, and genomic profiles were generated with the Oncomine Focus Assay (OFA). A total of 1,864 participants yielded QC-approved genomic profiles. Covariates of interest were assessed at enrollment. Cumulative tobacco exposure, including smoking intensity (cigarettes per day), duration, and TSC, was quantified using the Comprehensive Smoking Index (CSI). In addition, smoking status (current vs. never) was recoded as a function of TSC in order to identify the time period during which major genomic alterations (GA) are most likely to occur. Descriptive statistics, generalized linear models, and generalized additive models were used to evaluate the association between CSI and the prevalence of GA across genes. All models were adjusted for potential confounders, including country, age, sex, NSCLC subtype, cancer stage and history of cancer.</jats:p> </jats:sec> <jats:sec> <jats:title>Results and Conclusions:</jats:title> <jats:p>A total of 1100 patients had complete genomic and tobacco exposure information. Among current smokers, median smoking intensity and duration were 20 cigarettes per day and 48 years, respectively, compared with 30 cigarettes per day and 47 years among former smokers. Ninety percent of former smokers had ceased tobacco use at least 10 years prior to diagnosis, with a median TSC of 1 year. CSI analysis identified 14 genes significantly associated with genomic alteration status, including EGFR, PIK3CA, ALK, MTOR, ERBB3, and RET. Higher CSI values (4th quartile) showed approximately double the frequency of genomic alterations compared with the lowest CSI quartile for ALK (16.2% vs. 8.7%), RET (12.8% vs. 6.9%), and MTOR (15% vs. 6.9%). Mid-range CSI values exhibited the lowest prevalence of alterations in EGFR (12.6% vs. 31%) and PIK3CA (6.9% vs. 14.5%). Overall, these findings support the value of CSI in refining exposure-genotype associations and the need for improves risk stratification efforts in diverse populations.</jats:p> </jats:sec> <jats:sec> <jats:title>Citation Format:</jats:title> <jats:p>Javiera Garrido, Evelin González, Alejandro Blanco, Gonzalo Sepúlveda-Hermosilla, Matias Freire, Solange Rivas, Katherine Marcelain, Gareth I. Owen, Carolina Ibañez, Alejandro H. Corvalan, Marcelo Garrido, Rodrigo Assar, Rodrigo Lizana, Javier Cáceres-Molina, Diego Ampuero, Liliana Ramos, Paola Pérez, Osvaldo Aren, Sara Chernilo, Cristina Fernández, María Loreto Spencer, Jacqueline Flores, Giuliano Bernal, Mónica Ahumada Olea, Germán Rasse, Carolina Sánchez, Maria Galli de Amorim, Emmanuel Dias-Neto, Helano C. Freitas, Ricardo Armisen. Effects of cumulative tobacco exposure on lung cancer genomic profiles in Latin Americans [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 6440.</jats:p> </jats:sec>
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The mutational landscape and actionable targets of gallbladder cancer: an ancestry-informed and comparative analysis of a Chilean population
(Frontiers Media SA, 2025-10-03)
José Ignacio Erices
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Evelin González
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Marcela Salgado
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Carol Barahona-Ponce
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Matías Freire
1
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Methylated Reprimo Cell-Free DNA as a Non-Invasive Biomarker for Gastric Cancer
(MDPI AG, 2025-04-03)
María José Maturana
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Oslando Padilla
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Pablo M. Santoro
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Maria Alejandra Alarcón
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Wilda Olivares
Restrictions resulting from the COVID-19 pandemic abruptly reversed the slow decline of the diagnosis and mortality rates of gastric cancer (GC). This scenario highlights the importance of developing cost-effective methods for mass screening and evaluation of treatment response. In this study, we evaluated a non-invasive method based on the circulating methylated cell-free DNA (cfDNA) of Reprimo (RPRM), a tumor suppressor gene associated with the development of GC. Methylated RPRM cfDNA was analyzed in three de-identified cohorts: Cohort 1 comprised 81 participants with GC and 137 healthy donors (HDs); Cohort 2 comprised 27 participants with GC undergoing gastrectomy and/or chemotherapy analyzed at the beginning and after three months of treatment; and Cohort 3 comprised 1105 population-based participants in a secondary prevention program who underwent esophagogastroduodenal (EGD) endoscopy. This cohort includes 180 normal participants, 845 participants with premalignant conditions (692 with chronic atrophic gastritis [AG] and 153 with gastric intestinal metaplasia/low-grade dysplasia [GIM/LGD]), 21 with high-grade dysplasia/early GC [HGD/eGC], and 59 with advanced GC [aGC]). A nested case-control substudy was performed using a combination of methylated RPRM cfDNA and pepsinogens (PG)-I/II ratio. The dense CpG island of the promoter region of the RPRM gene was bisulfite sequenced and analyzed to develop a fluorescence-based real-time PCR assay (MethyLight). This assay allows the determination of the absolute number of copies of methylated RPRM cfDNA. A targeted sequence of PCR amplicon products confirmed the gastric origin of the plasma-isolated samples. In Cohort 1, the mean value of GCs (32,240.00 copies/mL) was higher than that of the HD controls (139.00 copies/mL) (p < 0.0001). After dividing this cohort into training–validation subcohorts, we identified an area under the curve of 0.764 (95% confidence interval (CI) = 0.683–0.845) in the training group. This resulted in a cut-off value of 87.37 copies/mL (sensitivity 70.0% and specificity 80.2%). The validation subcohort predicted a sensitivity of 66.67% and a specificity of 83.33%. In Cohort 2 (monitoring treatment response), RPRM levels significantly decreased in responders (p = 0.0042) compared to non-responders. In Cohort 3 (population-based participants), 18.9% %, 24.1%, 30.7%, 47.0%, and 71.2% of normal, AG, GIM/LGD, HGD/eGC, and aGC participants tested positive for methylated RPRM cfDNA, respectively. Overall sensitivity and specificity in distinguishing normal/premalignant conditions vs. GC were 65.0% (95% CI 53.52% to 75.33%) and 75.9% (95% CI 73.16% to 78.49%), respectively, with an accuracy of 75.11% (95% CI 72.45% to 77.64%). Logistic regression analyses revealed an OR of 1.85 (95% CI 1.11–3.07, p = 0.02) and an odds ratio (OR) of 3.9 (95% CI 1.53–9.93, p = 0.004) for the risk of developing GIM/LGD and HGD/eGC, respectively. The combined methylated RPRM cfDNA and PG-I/II ratio reached a sensitivity of 78.9% (95% CI 54.43% to 93.95%) and specificity of 63.04% (95% CI 52.34% to 72.88%) for detecting HGD/eGC vs. three to six age- and sex-matched participants with premalignant conditions. Our results demonstrate that methylated RPRM cfDNA should be considered a direct biomarker for the non-invasive detection of GC and a predictive biomarker for treatment response.
1Scopus© Citations 4
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MET Exon 14 Skipping and Novel Actionable Variants: Diagnostic and Therapeutic Implications in Latin American Non-Small-Cell Lung Cancer Patients
(MDPI AG, 2024-12-22)
RIVAS VERA, SOLANGE VERÓNICA
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Romina V. Sepúlveda
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TAPIA DUFEY, JUAN IGNACIO
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Catalina Estay
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Vicente Soto
<jats:p>Targeted therapy indications for actionable variants in non-small-cell lung cancer (NSCLC) have primarily been studied in Caucasian populations, with limited data on Latin American patients. This study utilized a 52-genes next-generation sequencing (NGS) panel to analyze 1560 tumor biopsies from NSCLC patients in Chile, Brazil, and Peru. The RNA sequencing reads and DNA coverage were correlated to improve the detection of the actionable MET exon 14 skipping variant (METex14). The pathogenicity of MET variants of uncertain significance (VUSs) was assessed using bioinformatic methods, based on their predicted driver potential. The effects of the predicted drivers VUS T992I and H1094Y on c-MET signaling activation, proliferation, and migration were evaluated in HEK293T, BEAS-2B, and H1993 cell lines. Subsequently, c-Met inhibitors were tested in 2D and 3D cell cultures, and drug affinity was determined using 3D structure simulations. The prevalence of MET variants in the South American cohort was 8%, and RNA-based diagnosis detected 27% more cases of METex14 than DNA-based methods. Notably, 20% of METex14 cases with RNA reads below the detection threshold were confirmed using DNA analysis. The novel actionable T992I and H1094Y variants induced proliferation and migration through c-Met/Akt signaling. Both variants showed sensitivity to crizotinib and savolitinib, but the H1094Y variant exhibited reduced sensitivity to capmatinib. These findings highlight the importance of RNA-based METex14 diagnosis and reveal the drug sensitivity profiles of novel actionable MET variants from an understudied patient population.</jats:p>
Scopus© Citations 4 8
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Beyond tobacco: genomic disparities in lung cancer between smokers and never-smokers
(2024)
GARRIDO MANRIQUEZ, JAVIERA NICOLE
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Yanara Bernal
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Evelin González
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Alejandro Blanco
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Gonzalo Sepúlveda-Hermosilla
Scopus© Citations 5 13
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A Comprehensive Analysis of the Effect of A>I(G) RNA-Editing Sites on Genotoxic Drug Response and Progression in Breast Cancer
(2024)
Yanara A. Bernal
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Alejandro Blanco
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Eduardo A. Sagredo
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Karen Oróstica
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ALFARO CORTEZ, IVAN ESTEBAN
Dysregulated A>I(G) RNA editing, which is mainly catalyzed by ADAR1 and is a type of post-transcriptional modification, has been linked to cancer. A low response to therapy in breast cancer (BC) is a significant contributor to mortality. However, it remains unclear if there is an association between A>I(G) RNA-edited sites and sensitivity to genotoxic drugs. To address this issue, we employed a stringent bioinformatics approach to identify differentially RNA-edited sites (DESs) associated with low or high sensitivity (FDR 0.1, log2 fold change 2.5) according to the IC50 of PARP inhibitors, anthracyclines, and alkylating agents using WGS/RNA-seq data in BC cell lines. We then validated these findings in patients with basal subtype BC. These DESs are mainly located in non-coding regions, but a lesser proportion in coding regions showed predicted deleterious consequences. Notably, some of these DESs are previously reported as oncogenic variants, and in genes related to DNA damage repair, drug metabolism, gene regulation, the cell cycle, and immune response. In patients with BC, we uncovered DESs predominantly in immune response genes, and a subset with a significant association (log-rank test p < 0.05) between RNA editing level in LSR, SMPDL3B, HTRA4, and LL22NC03-80A10.6 genes, and progression-free survival. Our findings provide a landscape of RNA-edited sites that may be involved in drug response mechanisms, highlighting the value of A>I(G) RNA editing in clinical outcomes for BC.
Scopus© Citations 4 7
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Distinct Driver Pathway Enrichments and a High Prevalence of TSC2 Mutations in Right Colon Cancer in Chile: A Preliminary Comparative Analysis
(2024)
Camilo Tapia-Valladares
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Guillermo Valenzuela
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Evelin González Feliú
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Ignacio Maureira
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Jessica Toro
<jats:p>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.</jats:p>
Scopus© Citations 1 2
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Abstract C018: Disparities in the access to non-small cell lung cancer´s target therapies in Chile
(2023)
Solange V. Rivas
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Evelin González
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Alejandro Blanco
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Carolina Ibáñez
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Alejandro Corvalán
<jats:title>Abstract</jats:title> <jats:p>Comprehensive next-generation sequencing (NGS) panels designed to identify the tumor mutational profile are becoming the standard care to prescribe target therapies in developed countries. In non-small cell lung cancer (NSCLC), this approach significantly impacts the patient´s clinical results, measured as progression-free survival and/or overall survival, compared to conventional chemotherapies. However, as Latin American patients tend to experience more significant health disparities because of structural, sociodemographic, and psychosocial factors, in this work, our purpose is to measure the disparities in the access to NSCLC´s target therapies, specifically in Chile. DNAs and RNAs from 1643 NSCLC samples from Chile, Brazil, and Peru were sequenced to assess the mutational status in fifty-two cancer genes. After an NGS quality control, variants were called and annotated using the Variant Effect Predictor, Annovar, COSMIC, and OncoKB, to categorize somatic mutations. The following analysis focused on today’s actionable genes in NSCLC, with FDA-approved target therapies (EGFR, KRAS, ALK, MET, ERBB2, BRAF, ROS1, and RET). In this analysis, 46.5% of tumors evidenced driver mutations (764/1643); interestingly, from this subset, 86.9% showed one driver variant, 11.2% two drivers, 1.4% three drivers, and 0.5% evidenced between 4-6 driver mutations. However, 19.4% (495/1643) evidenced actionable variants. The most mutated genes and the most common actionable variants were 15.3% EGFR (37% EGFR L858R), followed by 4.9% KRAS (100% KRAS G12C), 4.5% ALK (95.4% EML4-ALK fusion), 3% MET (100% MET exon 14 skipping), and 2.3% ERBB2. Finally, 1.5% BRAF, 1% ROS1 gene fusions and 0.9% RET gene fusions. Considering the target therapies approved by Chile´s Instituto de Salud Publica until October 2021, and if all these patients were diagnosed in Chile, only 64% would receive a targeted drug. EGFR is the gene with more target therapies validated in Chile, although drugs against exon twenty insertion have not been approved yet. Chile does not account for any targeted treatment for patients with alterations in KRAS, MET, RET and ERBB2; although the FDA approved a specific drug against KRAS G12C very recently (May 28, 2021), different is the case of MET because the first inhibitor, crizotinib, was FDA approved four years ago. Interestingly, in 2021, two inhibitors against the most common MET alteration were FDA approved, but none have been approved in Chile yet. In Chile, almost all target therapies have been validated against EGFR, ALK, and BRAF; however, patients with KRAS, MET, RET, and ERBB2 cannot access specific drugs, so in these cases, the recommended therapeutic option is chemotherapy. It is important to note that the target drugs approval only ensures the availability of the drug in Chile. Still, few of the target drugs are part of financed drugs by the Chilean health system, so the question is, how could we increase the national access to existing target therapies?</jats:p> <jats:p>Citation Format: Solange V. Rivas, Evelin González, Alejandro Blanco, Carolina Ibáñez, Alejandro Corvalán, Marcelo Garrido, Gareth Owen, Katherine Marcelain, Ricardo Armisén. Disparities in the access to non-small cell lung cancer´s target therapies in Chile [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C018.</jats:p>
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