Exploring the role of ribosomal RNA modifications in cancer.

Recent advances have highlighted the significant roles of post-transcriptional modifications in rRNA in various cancers. Evidence suggests that dysregulation of rRNA modifications acts as a common denominator in cancer development, with alterations in these modifications conferring competitive advantages to cancer cells. Specifically, rRNA modifications modulate protein synthesis and favor the specialized translation of oncogenic programs, thereby contributing to the formation of a protumorigenic proteome in cancer cells. These findings reveal a novel regulatory layer mediated by changes in the deposition of rRNA chemical modifications. Moreover, inhibition of these modifications in vitro and in preclinical studies demonstrates potential therapeutic applications. The recurrence of altered rRNA modification patterns across different types of cancer underscores their importance in cancer progression, proposing them as potential biomarkers and novel therapeutic targets. This review will highlight the latest insights into how post-transcriptional rRNA modifications contribute to cancer progression and summarize the main developments and ongoing challenges in this research area.

Global and single-nucleotide resolution detection of 7-methylguanosine in RNA.

RNA modifications, including N-7-methylguanosine (m7G), are pivotal in governing RNA stability and gene expression regulation. The accurate detection of internal m7G modifications is of paramount significance, given recent associations between altered m7G deposition and elevated expression of the methyltransferase METTL1 in various human cancers. The development of robust m7G detection techniques has posed a significant challenge in the field of epitranscriptomics. In this study, we introduce two methodologies for the global and accurate identification of m7G modifications in human RNA. We introduce borohydride reduction sequencing (Bo-Seq), which provides base resolution mapping of m7G modifications. Bo-Seq achieves exceptional performance through the optimization of RNA depurination and scission, involving the strategic use of high concentrations of NaBH4, neutral pH and the addition of 7-methylguanosine monophosphate (m7GMP) during the reducing reaction. Notably, compared to NaBH4-based methods, Bo-Seq enhances the m7G detection performance, and simplifies the detection process, eliminating the necessity for intricate chemical steps and reducing the protocol duration. In addition, we present an antibody-based approach, which enables the assessment of m7G relative levels across RNA molecules and biological samples, however it should be used with caution due to limitations associated with variations in antibody quality between batches. In summary, our novel approaches address the pressing need for reliable and accessible methods to detect RNA m7G methylation in human cells. These advancements hold the potential to catalyse future investigations in the critical field of epitranscriptomics, shedding light on the complex regulatory roles of m7G in gene expression and its implications in cancer biology.

The impact of tRNA modifications on translation in cancer: identifying novel therapeutic avenues.

Recent advancements have illuminated the critical role of RNA modifications in post-transcriptional regulation, shaping the landscape of gene expression. This review explores how tRNA modifications emerge as critical players, fine-tuning functionalities that not only maintain the fidelity of protein synthesis but also dictate gene expression and translation profiles. Highlighting their dysregulation as a common denominator in various cancers, we systematically investigate the intersection of both cytosolic and mitochondrial tRNA modifications with cancer biology. These modifications impact key processes such as cell proliferation, tumorigenesis, migration, metastasis, bioenergetics and the modulation of the tumor immune microenvironment. The recurrence of altered tRNA modification patterns across different cancer types underscores their significance in cancer development, proposing them as potential biomarkers and as actionable targets to disrupt tumorigenic processes, offering new avenues for precision medicine in the battle against cancer.

N7-methylguanosine methylation of tRNAs regulates survival to stress in cancer.

Tumour progression and therapy tolerance are highly regulated and complex processes largely dependent on the plasticity of cancer cells and their capacity to respond to stress. The higher plasticity of cancer cells highlights the need for identifying targetable molecular pathways that challenge cancer cell survival. Here, we show that N7-guanosine methylation (m7G) of tRNAs, mediated by METTL1, regulates survival to stress conditions in cancer cells. Mechanistically, we find that m7G in tRNAs protects them from stress-induced cleavage and processing into 5' tRNA fragments. Our analyses reveal that the loss of tRNA m7G methylation activates stress response pathways, sensitising cancer cells to stress. Furthermore, we find that the loss of METTL1 reduces tumour growth and increases cytotoxic stress in vivo. Our study uncovers the role of m7G methylation of tRNAs in stress responses and highlights the potential of targeting METTL1 to sensitise cancer cells to chemotherapy.

METTL1 promotes tumorigenesis through tRNA-derived fragment biogenesis in prostate cancer.

Newly growing evidence highlights the essential role that epitranscriptomic marks play in the development of many cancers; however, little is known about the role and implications of altered epitranscriptome deposition in prostate cancer. Here, we show that the transfer RNA N7-methylguanosine (m7G) transferase METTL1 is highly expressed in primary and advanced prostate tumours. Mechanistically, we find that METTL1 depletion causes the loss of m7G tRNA methylation and promotes the biogenesis of a novel class of small non-coding RNAs derived from 5'tRNA fragments. 5'tRNA-derived small RNAs steer translation control to favour the synthesis of key regulators of tumour growth suppression, interferon pathway, and immune effectors. Knockdown of Mettl1 in prostate cancer preclinical models increases intratumoural infiltration of pro-inflammatory immune cells and enhances responses to immunotherapy. Collectively, our findings reveal a therapeutically actionable role of METTL1-directed m7G tRNA methylation in cancer cell translation control and tumour biology.

Epigenetic and Epitranscriptomic Control in Prostate Cancer.

The initiation of prostate cancer has been long associated with DNA copy-number alterations, the loss of specific chromosomal regions and gene fusions, and driver mutations, especially those of the Androgen Receptor. Non-mutational events, particularly DNA and RNA epigenetic dysregulation, are emerging as key players in tumorigenesis. In this review we summarize the molecular changes linked to epigenetic and epitranscriptomic dysregulation in prostate cancer and the role that alterations to DNA and RNA modifications play in the initiation and progression of prostate cancer.

The role of m6A, m5C and Ψ RNA modifications in cancer: Novel therapeutic opportunities.

RNA modifications have recently emerged as critical posttranscriptional regulators of gene expression programmes. Significant advances have been made in understanding the functional role of RNA modifications in regulating coding and non-coding RNA processing and function, which in turn thoroughly shape distinct gene expression programmes. They affect diverse biological processes, and the correct deposition of many of these modifications is required for normal development. Alterations of their deposition are implicated in several diseases, including cancer. In this Review, we focus on the occurrence of N6-methyladenosine (m6A), 5-methylcytosine (m5C) and pseudouridine (Ψ) in coding and non-coding RNAs and describe their physiopathological role in cancer. We will highlight the latest insights into the mechanisms of how these posttranscriptional modifications influence tumour development, maintenance, and progression. Finally, we will summarize the latest advances on the development of small molecule inhibitors that target specific writers or erasers to rewind the epitranscriptome of a cancer cell and their therapeutic potential.

Emerging roles of novel small non-coding regulatory RNAs in immunity and cancer.

The term small non-coding RNAs (ncRNAs) refers to all those RNAs that even without encoding for a protein, can play important functional roles. Transfer RNA and ribosomal RNA-derived fragments (tRFs and rRFs, respectively) are an emerging class of ncRNAs originally considered as simple degradation products, which though play important roles in stress responses, signalling, or gene expression. They control all levels of gene expression regulating transcription and translation and affecting RNA processing and maturation. They have been linked to pivotal cellular processes such as self-renewal, differentiation, and proliferation. For this reason, mis-regulation of this novel class of ncRNAs can lead to various pathological processes such as neurodegenerative and development diseases, metabolism and immune system disorders, and cancer. In this review, we summarise the classification, biogenesis, and functions of tRFs and rRFs with a special focus on their role in immunity and cancer.

Post-transcriptional regulation by cytosine-5 methylation of RNA.

The recent advent of high-throughput sequencing technologies coupled with RNA modifications detection methods has allowed the detection of RNA modifications at single nucleotide resolution giving a more comprehensive landscape of post-transcriptional gene regulation pathways. In this review, we focus on the occurrence of 5-methylcytosine (m5C) in the transcriptome. We summarise the main findings of the molecular role in post-transcriptional regulation that governs m5C deposition in RNAs. Functionally, m5C deposition can regulate several cellular and physiological processes including development, differentiation and survival to stress stimuli. Despite many aspects concerning m5C deposition in RNA, such as position or sequence context and the fact that many readers and erasers still remain elusive, the overall recent findings indicate that RNA cytosine methylation is a powerful mechanism to post-transcriptionally regulate physiological processes. In addition, mutations in RNA cytosine-5 methyltransferases are associated to pathological processes ranging from neurological syndromes to cancer.

Considerations for skin carcinogenesis experiments using inducible transgenic mouse models.

OBJECTIVE: This study was designed to estimate the percentage of non-malignant skin tumours (papillomas) progressing to malignant squamous cell carcinomas (SCCs) in a carcinogenesis study using established transgenic mouse models. In our skin cancer model, we conditionally induced oncogenic point mutant alleles of p53 and k-ras in undifferentiated, basal cells of the epidermis. RESULTS: Upon activation of the transgenes through administration of tamoxifen, the vast majority of mice (> 80%) developed skin papillomas, yet primarily around the mouth. Since these tumours hindered the mice eating, they rapidly lost weight and needed to be culled before the papillomas progressed to SCCs. The mouth papillomas formed regardless of the route of application, including intraperitoneal injections, local application to the back skin, or subcutaneous insertion of a tamoxifen pellet. Implantation of a slow releasing tamoxifen pellet into 18 mice consistently led to papilloma formation, of which only one progressed to a malignant SCC. Thus, the challenges for skin carcinogenesis studies using this particular cancer mouse model are low conversion rates of papillomas to SCCs and high frequencies of mouth papilloma formation.

Prevalence of human T-cell lymphotropic virus I and II in Colombian blood donors, 2001-2014: Implications for transfusion safety.

INTRODUCTION: The human T-cell lymphotropic virus (HTLV) 1 and 2 cause various clinical disorders associated with degenerative diseases. Blood transfusion is a primary mechanism of transmission that is associated with the use of cellular components such as red blood cells.  OBJECTIVE: To describe the epidemiology of HTLV 1 and 2 in blood donors in Colombia from 2001-2014.  MATERIALS AND METHODS: A retrospective analysis was performed using screening, reactivity and positivity for HTLV 1 and 2 data collected from 2001 to 2014 by Colombian blood banks and consolidated by the Instituto Nacional de Salud. Using this information, transfusion-associated infectivity was also estimated.  RESULTS: From 2001 to 2014, 60.2% of blood collected in Colombia was screened for HTLV 1 and 2 and had a cumulative reactivity of 0.30%. This was 20 times higher in Chocó (6.28%), where blood collection ended in 2004. Blood screening for HTLV reached 94.9% in 2014 with a positive concordance of 14.7%, and an estimated 406 unscreened, potentially infectious blood units were released. The majority of the unscreened blood units (215 units, 53%) came from Antioquia, a non-endemic department.  CONCLUSION: These results suggest that HTLV 1 and 2 infections are distributed in different areas of the country that were not previously classified as endemic. These findings support the importance of the universal screening of blood units to minimize the risk of infection through transfusion for this event.

Prevalencia de la infección con el virus linfotrópico de células T humanas de tipo 1 y 2 en donantes de sangre en Colombia, 2001-2014: implicaciones sobre la seguridad de la transfusión / Prevalence of human T-cell lymphotropic virus I and II in Colombian blood donors, 2001-2014: Implications for transfusion safety

Introducción. El virus linfotrópico de células T humanas (HTLV) de tipos 1 y 2 ocasiona trastornos clínicos asociados a enfermedades degenerativas y proliferativas. Entre sus principales mecanismos de transmisión está la transfusión, asociada principalmente al uso de componentes celulares como los glóbulos rojos. Objetivo. Describir la epidemiología del HTLV 1 y 2 en donantes de sangre en Colombia, entre 2001 y 2014. Materiales y métodos. Se hizo un análisis descriptivo y retrospectivo de la información enviada por la Red de Bancos de Sangre al Instituto Nacional de Salud sobre tamización, unidades reactivas y positividad para el HTLV 1 y 2 y sobre la estimación de riesgo de infección por la transfusión. Resultados. Entre 2001 y 2014 se hizo en Colombia la tamización para la detección de anticuerpos de HTLV 1 y 2 de 60,2 % de la sangre captada, con una tasa acumulada de unidades reactivas de 0,3 %. Dicha tasa fue 20 veces superior en el departamento de Chocó (6,28 %), pese a que allí no se capta sangre desde el 2004. En el 2014, la tamización llegó a 94,9 %, con una positividad de 14,7 %. Con estos datos se pudo estimar que se transfundieron 406 unidades de glóbulos rojos potencialmente infecciosos, lo cual entrañaría una transmisión eficaz del virus a estos individuos. Pese a que no se le considera un departamento endémico, en Antioquia se registró la mayor proporción de pruebas positivas, con 215 unidades (53 %). Conclusiones. Los resultados obtenidos sugieren que la infección por HTLV 1 y 2 se distribuye en varias zonas del país que no eran catalogadas como endémicas. Se ratificó la importancia de la tamización universal de las unidades de sangre captadas, para minimizar el riesgo de infección con este agente por la vía de la transfusión.

Introduction: The human T-cell lymphotropic virus (HTLV) 1 and 2 cause various clinical disorders associated with degenerative diseases. Blood transfusion is a primary mechanism of transmission that is associated with the use of cellular components such as red blood cells. Objective: To describe the epidemiology of HTLV 1 and 2 in blood donors in Colombia from 2001-2014. Materials and methods: A retrospective analysis was performed using screening, reactivity and positivity for HTLV 1 and 2 data collected from 2001 to 2014 by Colombian blood banks and consolidated by the Instituto Nacional de Salud . Using this information, transfusion-associated infectivity was also estimated. Results: From 2001 to 2014, 60.2% of blood collected in Colombia was screened for HTLV 1 and 2 and had a cumulative reactivity of 0.30%. This was 20 times higher in Chocó (6.28%), where blood collection ended in 2004. Blood screening for HTLV reached 94.9% in 2014 with a positive concordance of 14.7%, and an estimated 406 unscreened, potentially infectious blood units were released. The majority of the unscreened blood units (215 units, 53%) came from Antioquia, a non-endemic department. Conclusion: These results suggest that HTLV 1 and 2 infections are distributed in different areas of the country that were not previously classified as endemic. These findings support the importance of the universal screening of blood units to minimize the risk of infection through transfusion for this event.

Stem cell function and stress response are controlled by protein synthesis.

Whether protein synthesis and cellular stress response pathways interact to control stem cell function is currently unknown. Here we show that mouse skin stem cells synthesize less protein than their immediate progenitors in vivo, even when forced to proliferate. Our analyses reveal that activation of stress response pathways drives both a global reduction of protein synthesis and altered translational programmes that together promote stem cell functions and tumorigenesis. Mechanistically, we show that inhibition of post-transcriptional cytosine-5 methylation locks tumour-initiating cells in this distinct translational inhibition programme. Paradoxically, this inhibition renders stem cells hypersensitive to cytotoxic stress, as tumour regeneration after treatment with 5-fluorouracil is blocked. Thus, stem cells must revoke translation inhibition pathways to regenerate a tissue or tumour.

Posttranscriptional methylation of transfer and ribosomal RNA in stress response pathways, cell differentiation, and cancer.

PURPOSE OF REVIEW: Significant advances have been made in understanding the functional roles of evolutionarily conserved chemical modifications in RNA. By focusing on cytosine-5 methylation, we will highlight the latest insight into the mechanisms how posttranscriptional methylation contributes to cell fate decisions, with implications for cancer development. RECENT FINDINGS: Several mutations in RNA-modifying enzymes have been identified to cause complex human diseases, and linked posttranscriptional modifications to fundamental cellular processes. Distinct posttranscriptional modifications are implicated in the regulation of stem cell maintenance and cellular differentiation. The dynamic deposition of a methyl mark into noncoding RNAs modulates the adaptive cellular responses to stress and alterations of methylation levels may lead to cancer. SUMMARY: Posttranscriptional modifications such as cytosine-5 methylation are dynamically regulated and may influence tumour development, maintenance, and progression.

Role of RNA methyltransferases in tissue renewal and pathology.

Over the last five decades more than 100 types of RNA modifications have been identified in organism of all kingdoms of life, yet their function and biological relevance remain largely elusive. The recent development of transcriptome-wide techniques to detect RNA modifications such as N(6)-methyladenosine (m(6)A) and 5-methylcytidine (m(5)C) has not only created a new field of research 'the epitranscriptome' but also featured essential regulatory roles of RNA methylation in a wide range of fundamental cellular processes. Here, we discuss the current knowledge of m(6)A and m(5)C RNA methylation pathways and summarize how they impact normal tissues and contribute to human disease.

Vaccinia-related kinase 1 (VRK1) confers resistance to DNA-damaging agents in human breast cancer by affecting DNA damage response.

Vaccinia-related kinase 1 (VRK1) belongs to a group of sixteen kinases associated to a poorer prognosis in human breast carcinomas, particularly in estrogen receptor positive cases based on gene expression arrays. In this work we have studied the potential molecular mechanism by which the VRK1 protein can contribute to a poorer prognosis in this disease. For this aim it was first analyzed by immunohistochemistry the VRK1 protein level in normal breast and in one hundred and thirty six cases of human breast cancer. The effect of VRK1 to protect against DNA damage was determined by studying the effect of its knockdown on the formation of DNA repair foci assembled on 53BP1 in response to treatment with ionizing radiation or doxorubicin in two breast cancer cell lines. VRK1 protein was detected in normal breast and in breast carcinomas at high levels in ER and PR positive tumors. VRK1 protein level was significantly lower in ERBB2 positive cases. Next, to identify a mechanism that can link VRK1 to poorer prognosis, VRK1 was knocked-down in two breast cancer cell lines that were treated with ionizing radiation or doxorubicin, both inducing DNA damage. Loss of VRK1 resulted in reduced formation of DNA-damage repair foci complexes assembled on the 53BP1 scaffold protein, and this effect was independent of damaging agent or cell type. This observation is consistent with detection of high VRK1 protein levels in ER and PR positive breast cancers. We conclude that VRK1 can contribute to make these tumors more resistant to DNA damage-based therapies, such as ionizing radiation or doxorubicin, which is consistent with its association to a poor prognosis in ER positive breast cancer. VRK1 is potential target kinase for development of new specific inhibitors which can facilitate sensitization to other treatments in combination therapies; or alternatively be used as a new cancer drugs.

Characterizing 5-methylcytosine in the mammalian epitranscriptome.

The post-transcriptional modification 5-methylcytosine (m5C) occurs in a wide range of coding and non-coding RNAs. We describe transcriptome-wide approaches to capture the global m5C RNA methylome. We also discuss the potential functions of m5C in RNA and compare them to 6-methyladenosine modifications.

Videoconferencia en línea comoherramienta de enseñanza de anomalías dentomaxilofaciales a residentes de ortodoncia. Una narración académica docente / Online videoconference as a tool for teaching dentofacial deformities to post-doctoral students in orthodontics: a professor’s scholarly narrative

Objetivo: Describir y analizar, a través de una narrativa académica docente, una experienciade dos años en el manejo de la videoconferencia en línea como herramienta de enseñanzaa distancia de anomalías dentomaxilofaciales (ADF). Método: Se utiliza el método denarración autobiográfica cualitativa para describir la experiencia docente. Este se usa eneducación y humanidades. La narración combina elementos de reflexión con la descripcióny análisis de las experiencias al enseñar por medio de videoconferencia. Resultados: Sepresentan tres puntos importantes. El primero es el tipo de clases que se ha implementadoy su metodología. El segundo es cómo lograr que el estudiante sienta la interacción conel docente en el proceso de aprendizaje. El tercero es cómo controlar los factores relacionadascon la tecnología. Conclusión: Se generan propuestas de estudios para evaluarcientíficamente la cátedra de ADF cuando se usa videoconferencia en línea...

Aim: Describe and analyze through a professor’s scholarly narrative a two-year experienceusing online videoconference as a tool for long distance teaching the dentofacial deformities’subject. Method: Qualitative autobiographical narrative is used as a method todescribe the teaching experience. This method is used in education and humanities. Thenarrative combines elements of reflection with the description and analysis of the teachingexperiences using videoconference. Results: Three important points are presented. The firstone is the class format and methodology. The second aspect is how to make the studentfeel the interactive guidance with the professor in the learning process. The third one is howto control the factors related to technology. As a conclusion, some studies are proposedto give scientific support to the teaching learning process through online videoconference...

VRK2 anchors KSR1-MEK1 to endoplasmic reticulum forming a macromolecular complex that compartmentalizes MAPK signaling.

The spatial and temporal regulation of intracellular signaling is determined by the spatial and temporal organization of complexes assembled on scaffold proteins, which can be modulated by their interactions with additional proteins as well as subcellular localization. The scaffold KSR1 protein interacts with MAPK forming a complex that conveys a differential signaling in response to growth factors. The aim of this work is to determine the unknown mechanism by which VRK2A downregulates MAPK signaling. We have characterized the multiprotein complex formed by KSR1 and the Ser-Thr kinase VRK2A. VRK2A is a protein bound to the endoplasmic reticulum (ER) and retains a fraction of KSR1 complexes on the surface of this organelle. Both proteins, VRK2A and KSR1, directly interact by their respective C-terminal regions. In addition, MEK1 is also incorporated in the basal complex. MEK1 independently interacts with the CA5 region of KSR1 and with the N-terminus of VRK2A. Thus, VRK2A can form a high molecular size (600-1,000 kDa) stable complex with both MEK1 and KSR1. Knockdown of VRK2A resulted in disassembly of these high molecular size complexes. Overexpression of VRK2A increased the amount of KSR1 in the particulate fraction and prevented the incorporation of ERK1/2 into the complex after stimulation with EGF. Neither VRK2A nor KSR1 interact with the VHR, MKP1, MKP2, or MKP3 phosphatases. The KSR1 complex assembled and retained by VRK2A in the ER can have a modulatory effect on the signal mediated by MAPK, thus locally affecting the magnitude of its responses, and can explain differential responses depending on cell type.