bims-ectoca Biomed News
on Epigenetic control of tolerance in cancer
Issue of 2023‒10‒29
seven papers selected by
Ankita Daiya, Birla Institute of Technology and Science



  1. Cancers (Basel). 2023 Oct 12. pii: 4956. [Epub ahead of print]15(20):
      Yes-associated Protein (YAP) and its paralog Transcriptional Coactivator with PDZ-binding Motif (TAZ) are major regulators of gene transcription/expression, primarily controlled by the Hippo pathway and the cytoskeleton. Integrating an array of chemical and mechanical signals, they impact growth, differentiation, and regeneration. Accordingly, they also play key roles in tumorigenesis and metastasis formation. Their activity is primarily regulated by their localization, that is, Hippo pathway- and/or cytoskeleton-controlled cytosolic or nuclear sequestration. While many details of such prevailing retention models have been elucidated, much less is known about their actual nuclear traffic: import and export. Although their size is not far from the cutoff for passive diffusion through the nuclear pore complex (NPC), and they do not contain any classic nuclear localization (NLS) or nuclear export signal (NES), evidence has been accumulating that their shuttling involves mediated and thus regulatable/targetable processes. The aim of this review is to summarize emerging information/concepts about their nucleocytoplasmic shuttling, encompassing the relevant structural requirements (NLS, NES), nuclear transport receptors (NTRs, karyophererins), and NPC components, along with the potential transport mechanisms and their regulation. While dissecting retention vs. transport is often challenging, the emerging picture suggests that YAP/TAZ shuttles across the NPC via multiple, non-exclusive, mediated mechanisms, constituting a novel and intriguing facet of YAP/TAZ biology.
    Keywords:  YAP/TAZ/Yorkie; importins and exportins; mediated nuclear import; nuclear export; nuclear import signal and nuclear export sequence; nuclear pore complex
    DOI:  https://doi.org/10.3390/cancers15204956
  2. bioRxiv. 2023 Oct 05. pii: 2023.10.03.560616. [Epub ahead of print]
      Repressive chromatin modifications are thought to compact chromatin to silence transcription. However, it is unclear how chromatin structure changes during silencing and epigenetic memory formation. We measured gene expression and chromatin structure in single cells after recruitment and release of repressors at a reporter gene. Chromatin structure is heterogeneous, with open and compact conformations present in both active and silent states. Recruitment of repressors associated with epigenetic memory produces chromatin compaction across 10-20 kilobases, while reversible silencing does not cause compaction at this scale. Chromatin compaction is inherited, but changes molecularly over time from histone methylation (H3K9me3) to DNA methylation. The level of compaction at the end of silencing quantitatively predicts epigenetic memory weeks later. Similarly, chromatin compaction at the Nanog locus predicts the degree of stem-cell fate commitment. These findings suggest that the chromatin state across tens of kilobases, beyond the gene itself, is important for epigenetic memory formation.
    DOI:  https://doi.org/10.1101/2023.10.03.560616
  3. Heliyon. 2023 Oct;9(10): e20183
      Epithelial-to-mesenchymal transition (EMT) is associated with an invasive phenotype in colorectal cancer (CRC). Here, we examined the roles of YES-associated protein (YAP) and syndecan-2 (SDC2) in EMT-related progression, invasion, metastasis, and drug resistance in CRC. The expression levels of YAP and SDC2 in CRC patient tumor tissue were quantified by PCR and western blotting. EMT-associated characteristics were assessed using Transwell assays and immunohistochemistry. Co-immunoprecipitation, glutathione S-transferase pull-down, and luciferase reporter assays were used to assess interactions between YAP and SDC2. YAP was found to be highly expressed in tumor tissue from 13/16 CRC patients, while SDC2 was highly expressed in the tumor tissue of 12/16 CRC patients. Overexpression of YAP in colon cancer cells led to increased cell viability, invasion, migration, and oxaliplatin resistance demonstrating that YAP plays a role in EMT. In addition, overexpression of YAP led to decreased expression of the large tumor suppressor kinase 1 (LATS1) and mammalian sterile 20-like kinases (MST1/2). Decreased LATS1 expression was associated with increased levels of cell proliferation. Knockdown of YAP by shRNA interference led to decreased cell invasion, migration, and drug resistance in colon cancer cells and reduced tumorigenesis in a mouse xenograft model. Finally, we established that YAP interacted with SDC2, and demonstrated that SDC2 mediated the YAP pathway through the EMT-related factors BMP4, CTGF and FOXM1.
    Keywords:  Colorectal cancer; Drug resistance; Metastasis; SDC2; YAP
    DOI:  https://doi.org/10.1016/j.heliyon.2023.e20183
  4. Mol Oncol. 2023 Oct 23.
      The development of tailored therapies designed to specifically target driver oncogenes has initiated a revolutionary era in cancer biology. The availability of a growing number of selective inhibitors has generated novel experimental and clinical paradigms. These represent an opportunity and a challenge for researchers and clinicians to delve deeper into the intricate dynamics of cancer development and response to treatment. By directly inhibiting key driver oncogenes involved in tumor initiation and progression, scientists have an unprecedented opportunity to conduct longitudinal and clonal evolutionary studies of how cancer cells adapt, rewire and exploit conflictive or overlapping signaling dependencies in response to treatment in vitro and in vivo. This challenge has to be progressively resolved to discover more effective and personalized cancer therapies.
    Keywords:  Driver oncogenes; Drug resistance; Signaling rewiring
    DOI:  https://doi.org/10.1002/1878-0261.13547
  5. Cancers (Basel). 2023 Oct 19. pii: 5044. [Epub ahead of print]15(20):
      Malignant bone tumors are commonly classified as pediatric or adolescent malignancies, and clinical trials for these diseases have generally focused on these populations. Of primary bone cancers, osteosarcoma is among the most common. Osteosarcoma has a bimodal age distribution, with the first peak occurring in patients from 10 to 14 years old, and the second peak occurring in patients older than 65, with about 25% of cases occurring in adults between 20 and 59 years old. Notably, adult osteosarcoma patients have worse outcomes than their pediatric counterparts. It remains unclear whether age itself is a poor prognostic factor, or if inherent differences in tumor biology exist between age groups. Despite these unknowns, current treatment strategies for adults are largely extrapolated from pediatric studies since the majority of clinical trials for osteosarcoma treatments are based on younger patient populations. In light of the different prognoses observed in pediatric and adult osteosarcoma, we summarize the current understanding of the molecular etiology of osteosarcoma and how it may differ between age groups, hypothesizing why adult patients have worse outcomes compared to children.
    Keywords:  AYA; adolescent/young adult oncology; bone tumors; osteosarcoma; sarcoma
    DOI:  https://doi.org/10.3390/cancers15205044
  6. Int J Mol Sci. 2023 Oct 16. pii: 15222. [Epub ahead of print]24(20):
      This study aims to identify the mechanism of geniposide regulating oxidative stress in colorectal cancer (CRC) through network pharmacology and bioinformatics analysis. Targets of geniposide, oxidative stress-related targets and targets related to CRC were applied from databases. The hub genes for geniposide regulating oxidative stress in CRC were identified with the protein-protein interaction (PPI) network. Furthermore, we applied Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment to analyze the hub genes from a macro perspective. We verified the hub genes by molecular docking, GEPIA, HPA and starBase database. We identified five hub genes: IL1B, GSK3B, NOS3, RELA and CDK4. GO analysis results suggested that the anti-colorectal cancer effect of geniposide by regulating oxidative stress is possibly related to the influence of multiple biological processes, including response to temperature stimulus, response to alkaloid, nitric oxide biosynthetic process, nitric oxide metabolic process, reactive nitrogen species metabolic process, cellular response to peptide, etc. KEGG enrichment analysis results indicated that the PI3K-Akt signaling pathway, IL-17 signaling pathway, p53 signaling pathway, NF-κB signaling pathway and NOD-like receptor signaling pathway are likely to be the significant pathways. Molecular docking results showed that the geniposide had a good binding activity with the hub genes. This study demonstrates that geniposide can regulate oxidative stress in CRC, and induction of oxidative stress is one of the possible mechanisms of anti-recurrence and metastasis effects of geniposide against CRC.
    Keywords:  CRC; bioinformatics; geniposide; molecular docking; network pharmacology; oxidative stress
    DOI:  https://doi.org/10.3390/ijms242015222
  7. Int J Mol Sci. 2023 Oct 17. pii: 15242. [Epub ahead of print]24(20):
      Changes in epigenetic programming have been proposed as being key events in the initiation and progression of childhood cancers. HMT euchromatic histone lysine methyltransferase 2 (G9a, EHMT2), which is encoded by the G9a (Ehmt2) gene, as well as its related protein GLP, which is encoded by the GLP/Ehmt1 gene, participate in epigenetic regulation by contributing to a transcriptionally repressed chromatin state. G9a/GLP activation has been reported in several cancer types. Herein, we evaluated the role of G9a in two solid pediatric tumors: neuroblastoma (NB) and Ewing sarcoma (ES). Our results show that G9a/Ehmt2 and GLP/Ehmt1 expression is higher in tumors with poorer prognosis, including St4 International Neuroblastoma Staging System (INSS) stage, MYCN amplified NB, and metastatic ES. Importantly, higher G9a and GLP levels were associated with shorter patient overall survival (OS) in both NB and ES. Moreover, pharmacological inhibition of G9a/GLP reduced cell viability in NB and ES cells. These findings suggest that G9a and GLP are associated with more aggressive NB and ES tumors and should be further investigated as being epigenetic targets in pediatric solid cancers.
    Keywords:  Ewing sarcoma; G9a; GLP; histone methyltransferase; neuroblastoma; pediatric cancer
    DOI:  https://doi.org/10.3390/ijms242015242