1,720,978 research outputs found
p38α, the β-catenin chromatin associated kinase, as promising target in colorectal cancer stem cells for personalized therapy
Full text linkColorectal cancer (CRC) is the third most frequent malignancy, but the second cause of death for tumor in the western population. Only 14% of patients with advanced and metastatic disease survive five years from diagnosis. Recently, it has been shown that tumor relapse and chemoresistance depend on a small population of cells, called cancer stem cells (CSCs). Current evidence indicates that the Wnt cascade is the main driver in controlling CSC fate; the key player in this pathway is β-catenin, a cytoplasmic protein whose stability is regulated by the so-called “destruction complex”. During carcinogenesis, the increasing amount of β-catenin resulting from APC inactivation translocates into the nucleus, causing the transcriptional activation of several mitogenic genes, including c-Myc. c-Myc is one of the most important factors involved in CRC initiation and progression; indeed, it functions as a link connecting malignancy with stemness. During colorectal carcinogenesis, c-Myc is maintained upregulated through β-catenin-mediated transcriptional activation and ERK-mediated post-translational stabilization. Our data showed that p38α, a kinase involved in CRC metabolism and survival, contributes to both mechanisms. Previous reports in other tissues provided evidence that Wnt3a can activate p38, and the p38 pathway feeds into the canonical Wnt/β-catenin pathway at least at the level of GSK3β. Our findings also highlighted that CRC cells and colorectal cancer stem cells (CRC-SCs) have higher levels of activated p38 than their normal counterparts, and experiments using kinase-specific inhibitors revealed that these cells are “addicted” to p38 activity. Importantly, we found that p38α co-immunoprecipitates with β-catenin in both normal and cancer cells; however, these proteins are confined to the cytoplasm in colonocytes, while they significantly occupy discrete nuclear regions in CRC cells, CRC-SCs, and in vivo models. These data were further corroborated by the inhibitory effect of p38α blockade on several β-catenin-responsive genes (i.e. c-Myc, cyclin D1/2, survivin, and others). This functional interaction was further characterized by chromatin immunoprecipitation experiments, which demonstrated that p38α is a chromatin-associated β-catenin kinase required for the transcriptional induction of several Wnt target genes, including c-Myc. Additionally, we demonstrated that p38α, like ERK, stabilizes c-Myc protein levels by preventing its ubiquitination. The finding that the phenotypes arising after APC loss in the intestine are fully dependent on c-Myc target gene expression suggests that c-Myc inhibition may be a good target for chemoprevention in CRC. These considerations underline the relevance of molecular profiling and preclinical investigation in order to achieve more efficient and accurate therapies. Indeed, our study identifies p38α as a promising therapeutic target acting directly on c-Myc and CRC-SCs, which are thought to be responsible for tumor proliferation, metastatic dissemination, and chemoresistance
Colorectal Cancer Chemoprevention: A Dream Coming True?
No full textColorectal cancer (CRC) is one of the deadliest forms of cancer worldwide. CRC development occurs mainly through the adenoma-carcinoma sequence, which can last decades, giving the opportunity for primary prevention and early detection. CRC prevention involves different approaches, ranging from fecal occult blood testing and colonoscopy screening to chemoprevention. In this review, we discuss the main findings gathered in the field of CRC chemoprevention, focusing on different target populations and on various precancerous lesions that can be used as efficacy evaluation endpoints for chemoprevention. The ideal chemopreventive agent should be well tolerated and easy to administer, with low side effects. Moreover, it should be readily available at a low cost. These properties are crucial because these compounds are meant to be used for a long time in populations with different CRC risk profiles. Several agents have been investigated so far, some of which are currently used in clinical practice. However, further investigation is needed to devise a comprehensive and effective chemoprevention strategy for CRC
Identifying novel SMYD3 interactors on the trail of cancer hallmarks
Full text linkSMYD3 overexpression in several human cancers highlights its crucial role in carcinogenesis.
Nonetheless, SMYD3 specific activity in cancer development and progression is currently under debate.
Taking advantage of a library of rare tripeptides, which we first tested for their in vitro binding affinity
to SMYD3 and then used as in silico probes, we recently identified BRCA2, ATM, and CHK2 as direct
SMYD3 interactors. To gain insight into novel SMYD3 cancer-related roles, here we performed a comprehensive
in silico analysis to cluster all potential SMYD3-interacting proteins identified by screening the
human proteome for the previously tested tripeptides, based on their involvement in cancer hallmarks.
Remarkably, we identified mTOR, BLM, MET, AMPK, and p130 as new SMYD3 interactors implicated in
cancer processes. Further studies are needed to characterize the functional mechanisms underlying these
interactions. Still, these findings could be useful to devise novel therapeutic strategies based on the combined
inhibition of SMYD3 and its newly identified molecular partners. Of note, our in silico methodology
may be useful to search for unidentified interactors of other proteins of interest
Uncoupling p38α nuclear and cytoplasmic functions and identification of two p38α phosphorylation sites on β-catenin: implications for the Wnt signaling pathway in CRC models
No full textBackground: Activation of the Wnt pathway has been linked to colorectal cancer (CRC). Previous reports suggest that Wnt3a can activate p38. Besides, p38α feeds into the canonical Wnt/β-catenin pathway by inhibiting GSK3β through phosphorylation. Recently, we identified p38α as a new druggable member of β-catenin chromatin-associated kinase complexes in CRC. Methods: The functional relationship between p38α and β-catenin was characterized in CRC cells, patient-derived CRC stem cells, patient-derived tumor intestinal organoids, and in vivo models (C57BL/6-APCMin/+ mice). The role of p38α in β-catenin transcriptional activity was assessed by pharmacological inhibition with ralimetinib. Results: We used the GSK3β inhibitor TWS-119, which promotes the activation of Wnt signaling, to uncouple p38α nuclear/cytoplasmatic functions in the Wnt pathway. Upon GSK3β inhibition, nuclear p38α phosphorylates β-catenin at residues S111 and T112, allowing its binding to promoter regions of Wnt target genes and the activation of a transcriptional program implicated in cancer progression. If p38α is pharmacologically inhibited in addition to GSK3β, β-catenin is prevented from promoting target gene transcription, which is expected to impair carcinogenesis. Conclusions: p38α seems to play a dual role as a member of the β-catenin destruction complex and as a β-catenin chromatin-associated kinase in CRC. This finding may help elucidate mechanisms contributing to human colon tumor pathogenesis and devise new strategies for personalized CRC treatment
In Silico Deciphering of the Potential Impact of Variants of Uncertain Significance in Hereditary Colorectal Cancer Syndromes
No full textColorectal cancer (CRC) ranks third in terms of cancer incidence worldwide and is responsible for 8% of all deaths globally. Approximately 10% of CRC cases are caused by inherited pathogenic mutations in driver genes involved in pathways that are crucial for CRC tumorigenesis and progression. These hereditary mutations significantly increase the risk of initial benign polyps or adenomas developing into cancer. In recent years, the rapid and accurate sequencing of CRC-specific multigene panels by next-generation sequencing (NGS) technologies has enabled the identification of several recurrent pathogenic variants with established functional consequences. In parallel, rare genetic variants that are not characterized and are, therefore, called variants of uncertain significance (VUSs) have also been detected. The classification of VUSs is a challenging task because each amino acid has specific biochemical properties and uniquely contributes to the structural stability and functional activity of proteins. In this scenario, the ability to computationally predict the effect of a VUS is crucial. In particular, in silico prediction methods can provide useful insights to assess the potential impact of a VUS and support additional clinical evaluation. This approach can further benefit from recent advances in artificial intelligence-based technologies. In this review, we describe the main in silico prediction tools that can be used to evaluate the structural and functional impact of VUSs and provide examples of their application in the analysis of gene variants involved in hereditary CRC syndromes
FOXO3a from the Nucleus to the Mitochondria: A Round Trip in Cellular Stress Response
Full text linkCellular stress response is a universal mechanism that ensures the survival or negative selection of cells in challenging conditions. The transcription factor Forkhead box protein O3 (FOXO3a) is a core regulator of cellular homeostasis, stress response, and longevity since it can modulate a variety of stress responses upon nutrient shortage, oxidative stress, hypoxia, heat shock, and DNA damage. FOXO3a activity is regulated by post-translational modifications that drive its shuttling between different cellular compartments, thereby determining its inactivation (cytoplasm) or activation (nucleus and mitochondria). Depending on the stress stimulus and subcellular context, activated FOXO3a can induce specific sets of nuclear genes, including cell cycle inhibitors, pro-apoptotic genes, reactive oxygen species (ROS) scavengers, autophagy effectors, gluconeogenic enzymes, and others. On the other hand, upon glucose restriction, 5'-AMP-activated protein kinase (AMPK) and mitogen activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) -dependent FOXO3a mitochondrial translocation allows the transcription of oxidative phosphorylation (OXPHOS) genes, restoring cellular ATP levels, while in cancer cells, mitochondrial FOXO3a mediates survival upon genotoxic stress induced by chemotherapy. Interestingly, these target genes and their related pathways are diverse and sometimes antagonistic, suggesting that FOXO3a is an adaptable player in the dynamic homeostasis of normal and stressed cells. In this review, we describe the multiple roles of FOXO3a in cellular stress response, with a focus on both its nuclear and mitochondrial functions
Understanding the Genetic Landscape of Pancreatic Ductal Adenocarcinoma to Support Personalized Medicine: A Systematic Review
No full textSimple Summary Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with high mortality. Most patients present with an advanced stage of the disease, highlighting the urgent need for early detection. Recent studies of individuals at high risk of PDAC showed benefits from participating in clinical management and surveillance programs. PDAC clinical management and surveillance programs are suggested for individuals with a germline pathogenic variant in a cancer predisposition gene or a strong family history. In the present study, we performed a systematic literature review to investigate the mutational portrait of the main genes (ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, TP53) involved in PDAC susceptibility. Our findings may support the development of tailored management and follow-up strategies in PDAC patients with specific germline genetic variants.Abstract Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies worldwide. While population-wide screening recommendations for PDAC in asymptomatic individuals are not achievable due to its relatively low incidence, pancreatic cancer surveillance programs are recommended for patients with germline causative variants in PDAC susceptibility genes or a strong family history. In this study, we sought to determine the prevalence and significance of germline alterations in major genes (ATM, BRCA1, BRCA2, CDKN2A, EPCAM, MLH1, MSH2, MSH6, PALB2, PMS2, STK11, TP53) involved in PDAC susceptibility. We performed a systematic review of PubMed publications reporting germline variants identified in these genes in PDAC patients. Overall, the retrieved articles included 1493 PDAC patients. A high proportion of these patients (n = 1225/1493, 82%) were found to harbor alterations in genes (ATM, BRCA1, BRCA2, PALB2) involved in the homologous recombination repair (HRR) pathway. Specifically, the remaining PDAC patients were reported to carry alterations in genes playing a role in other cancer pathways (CDKN2A, STK11, TP53; n = 181/1493, 12.1%) or in the mismatch repair (MMR) pathway (MLH1, MSH2, MSH6, PMS2; n = 87/1493, 5.8%). Our findings highlight the importance of germline genetic characterization in PDAC patients for better personalized targeted therapies, clinical management, and surveillance
Identification and Somatic Characterization of the Germline PTEN Promoter Variant rs34149102 in a Family with Gastrointestinal and Breast Tumors
Full text linkGenetic variants located in non-coding regions can affect processes that regulate protein expression, functionally contributing to human disease. Germline heterozygous mutations in the non-coding region of the PTEN gene have been previously identified in patients with PTEN hamartoma tumor syndrome (PHTS) diagnosed with breast, thyroid, and/or endometrial cancer. In this study, we report a PTEN promoter variant (rs34149102 A allele) that was identified by direct sequencing in an Italian family with a history of gastroesophageal junction (GEJ) adenocarcinoma and breast cancer. In order to investigate the putative functional role of the rs34149102 A allele variant, we evaluated the status of PTEN alterations at the somatic level. We found that PTEN protein expression was absent in the GEJ adenocarcinoma tissue of the index case. Moreover, we detected the occurrence of copy number loss involving the PTEN rs34149102 major C allele in tumor tissue, revealing that the second allele was somatically inactivated. This variant is located within an active regulatory region of the PTEN core promoter, and in silico analysis suggests that it may affect the binding of the nuclear transcription factor MAZ and hence PTEN expression. Overall, these results reveal the functional role of the PTEN promoter rs34149102 A allele variant in the modulation of PTEN protein expression and highlight its contribution to hereditary cancer risk
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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