bims-ectoca Biomed News
on Epigenetic control of tolerance in cancer
Issue of 2022‒12‒04
nine papers selected by
Ankita Daiya
BITS Pilani

  1. Biol Direct. 2022 Dec 02. 17(1): 38
      Nuclear organisation and architecture are essential for the maintenance of genomic integrity as well as for the epigenetic regulations and gene expression. Disruption of lamin B1, major structural and functional member of the nuclear lamina, is observed in human laminopathies and in sporadic cancers, and leads to chromosomal rearrangements and alterations of gene expression. The tumour suppressor p53 has been shown to direct specific transcriptional programmes by regulating lamin A/C, however its relationship with lamin B1 has remained elusive. Here, we show that loss of p53 correlates with increased expression of members belonging to the nuclear pore complex and nuclear lamina and directly regulates transcription of lamin B1. We show that the genomic loci of a fraction of p53-dependent genes physically interact with lamin B1 and Nup210. This observation provides a possible mechanistic explanation for the p53-depedent changes of chromatin accessibility, with the consequent influence of expression and rearrangement of these genomic sites in pancreatic cancer. Overall, these data suggest a potential functional and biochemical regulatory network connecting p53 and nuclear architecture.
  2. Macromol Biosci. 2022 Dec 02. e2200438
      Cancer cells recognize physical cues transmitted from the surrounding microenvironment, and accordingly alter the migration and chemosensitivity. Cell adhesive biomaterials with tunable physical properties can contribute to the understanding of cancer cell responses, and development of new cancer therapies. Previously, we reported that polyrotaxane-based surfaces with molecular mobility effectively modulate cellular functions via the yes-associated protein (YAP)-related signaling pathway. In the present study, we investigate the impact of molecular mobility on polyrotaxane surfaces on the migration and chemosensitivity of lung (A549), pancreatic (BxPC-3), and breast cancer (MDA-MB-231) cell lines and found that the cellular spreading of adherent A549 and BxPC-3 cells and nuclear YAP translocation were promoted on low-mobility surfaces, suggesting that cancer cells alter their subcellular YAP localization in response to molecular mobility. Furthermore, low-mobility surfaces suppressed cellular migration more than high-mobility surfaces. Additionally, low-mobility surfaces promoted the cisplatin chemosensitivity of each cancer cell line to a greater extent than high-mobility surfaces. These results suggest that the molecular mobility of polyrotaxane surfaces suppresses cellular migration and enhances chemosensitivity via the subcellular translocation of YAP in cancer cells. Biointerfaces based on polyrotaxanes could thus be a new platform for elucidating cancer cell migration and chemoresistance mechanisms. This article is protected by copyright. All rights reserved.
    Keywords:  cancer; cellular migration; chemosensitivity; molecular mobility; polyrotaxanes
  3. Int J Cancer. 2022 Nov 28.
      Chromatin has an extremely flexible structure that allows the fine regulation of gene expression. To orchestrate this process, small chemical modifications are dynamically added or removed on DNA, RNA and histone substrates. Epigenetic modifications govern a plethora of key cellular functions, whose dysregulation contributes to oncogenesis. The interrelationship between (irreversible) genetic mutations and (reversible) epigenetic alterations and how this crosstalk regulates gene expression has long been a major area of interest. Marks modulating the RNA code (epitranscriptome), such as the well-studied N6 -methyladenosine (m6 A), are known to influence stability, metabolism and life cycle of many mRNAs, including cancer-associated transcripts. Together, epigenetic and epitranscriptomic pathways therefore control the entire cellular expression profile and, eventually, cell fate. Recently, previously undescribed crosstalk between these two pathways has started to be unrevealed. For example, m6 A and its effectors cooperate with histone modifications to localize chromatin-modifying complexes to their target regions. Epigenetic marks governing the expression of m6 A factors can also be found at specific genetic loci. m6 A itself can mark noncoding RNAs (including lncRNAs, circRNAs and miRNAs), influencing their structure, maturation and function. These interactions affect both cell physiology and pathology. Clear evidence that dysregulation of this network plays a role in cancer has emerged, suggesting a new layer of complexity in the landscape of gene expression. Here, we summarize current knowledge on the interplay between m6 A epitranscriptome and epigenome, focusing on cancer processes. We also discuss strategies to target m6 A machinery for future therapeutic intervention.
    Keywords:  RNA modifications; cancer; epigenetics; epitranscriptomics; m6A
  4. Front Physiol. 2022 ;13 999883
      Cholesterol-enriched domains are nowadays proposed to contribute to cancer cell proliferation, survival, death and invasion, with important implications in tumor progression. They could therefore represent promising targets for new anticancer treatment. However, although diverse strategies have been developed over the years from directly targeting cholesterol membrane content/distribution to adjusting sterol intake, all approaches present more or less substantial limitations. Those data emphasize the need to optimize current strategies, to develop new specific cholesterol-targeting anticancer drugs and/or to combine them with additional strategies targeting other lipids than cholesterol. Those objectives can only be achieved if we first decipher (i) the mechanisms that govern the formation and deformation of the different types of cholesterol-enriched domains and their interplay in healthy cells; (ii) the mechanisms behind domain deregulation in cancer; (iii) the potential generalization of observations in different types of cancer; and (iv) the specificity of some alterations in cancer vs. non-cancer cells as promising strategy for anticancer therapy. In this review, we will discuss the current knowledge on the homeostasis, roles and membrane distribution of cholesterol in non-tumorigenic cells. We will then integrate documented alterations of cholesterol distribution in domains at the surface of cancer cells and the mechanisms behind their contribution in cancer processes. We shall finally provide an overview on the potential strategies developed to target those cholesterol-enriched domains in cancer therapy.
    Keywords:  anticancer therapy; apoptosis; cancer; caveolae; cell migration; cell proliferation; lipid rafts; submicrometric domains
  5. Nat Commun. 2022 Nov 28. 13(1): 7199
      Breast cancer, the most frequent cancer in women, is generally classified into several distinct histological and molecular subtypes. However, single-cell technologies have revealed remarkable cellular and functional heterogeneity across subtypes and even within individual breast tumors. Much of this heterogeneity is attributable to dynamic alterations in the epigenetic landscape of the cancer cells, which promote phenotypic plasticity. Such plasticity, including transition from luminal to basal-like cell identity, can promote disease aggressiveness. We now report that the tumor suppressor LATS1, whose expression is often downregulated in human breast cancer, helps maintain luminal breast cancer cell identity by reducing the chromatin accessibility of genes that are characteristic of a "basal-like" state, preventing their spurious activation. This is achieved via interaction of LATS1 with the NCOR1 nuclear corepressor and recruitment of HDAC1, driving histone H3K27 deacetylation near NCOR1-repressed "basal-like" genes. Consequently, decreased expression of LATS1 elevates the expression of such genes and facilitates slippage towards a more basal-like phenotypic identity. We propose that by enforcing rigorous silencing of repressed genes, the LATS1-NCOR1 axis maintains luminal cell identity and restricts breast cancer progression.
  6. Yakugaku Zasshi. 2022 ;142(12): 1321-1326
      Although molecular targeted drugs are significantly effective in many types of cancer treatment, almost all patients suffer from drug resistance. For instance, non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation invariably develop resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) and melanoma patients with BRAF mutation develop resistance to BRAF inhibitors. Mechanistically, genetic and irreversible resistance mechanisms have been studied for more than a decade, while non-mutational and reversible resistance mechanisms are yet to be clearly understood. Since drug tolerant persisters (DTPs), which emerge at the beginning of the drug treatment, have been reported in 2010, several non-mutational tolerance mechanisms have been reported by various researchers. Furthermore, with the advancement in single cell sequencing technology, increasing attention has been drawn towards the investigation of the heterogeneous characteristics of drug tolerant cell populations. Here, we describe the recent advances in non-mutational drug tolerant mechanisms toward the molecular targeted drugs. In our study, we tried to elucidate the unconventional resistance mechanisms by utilizing newly approved EGFR-TKI, dacomitinib. Our established drug resistant cells did not gain new mutation in EGFR even after long time exposure to the drug. In addition, the drug resistance vanished when resistant cells were implanted in mice, which indicates that mechanisms conferring drug sensitivity might be host-dependent. Thus, our study may provide a new insight into non-mutational drug tolerant mechanisms.
    Keywords:  dacomitinib; drug resistance; drug tolerance; epidermal growth factor receptor
  7. MicroPubl Biol. 2022 ;2022
      Each of the three mammalian Ajuba family proteins, AJUBA, LIMD1 and WTIP, exhibit tension-dependent localization to adherens junctions, and can associate with Lats kinases. However, only LIMD1 has been directly demonstrated to directly regulate Lats activity in vivo. To assess the relationship of LIMD1 to AJUBA and WTIP, and the potential contributions of AJUBA and WTIP to Lats regulation, we examined the consequences of over-expressing AJUBA and WTIP in MCF10A cells. Over-expression of either AJUBA or WTIP reduced junctional localization of LIMD1, implying that these proteins can compete for binding to adherens junctions. This over-expression also reduced junctional localization of LATS1, implying that AJUBA or WTIP are unable to efficiently recruit Lats kinases to adherens junctions. This over-expression was also associated with increased YAP1 phosphorylation and decreased YAP1 nuclear localization, consistent with increased Lats kinase activity. These observations indicate that AJUBA and WTIP compete with LIMD1 for association with adherens junctions but have activities distinct from LIMD1 in Hippo pathway regulation. They further suggest that the ability of Ajuba family proteins to associate with Lats kinases in solution is not sufficient to enable regulation in vivo, and that tumor suppressor activities of AJUBA and WTIP could stem in part from competition with LIMD1 for regulation of Lats kinases at cell junctions.
  8. Curr Opin Chem Biol. 2022 Nov 24. pii: S1367-5931(22)00115-6. [Epub ahead of print]72 102230
      The p53 protein plays a critical role in the prevention of genome mutations in the body, however, this protein is frequently mutated in cancer and almost all cancers exhibit malfunction along the p53 pathway. In addition to a loss of activity, mutant p53 protein is prone to unfolding and aggregation, eventually forming amyloid aggregates. There continues to be a considerable effort to develop strategies to restore normal p53 expression and activity and this review details recent advances in small-molecule stabilization of mutant p53 protein and the design of p53 aggregation inhibitors.
    Keywords:  Aggregation inhibition; Amyloids; Cancer; Reactivation; Small-molecule binding; Zinc; p53 protein
  9. Cell Death Discov. 2022 Nov 26. 8(1): 465
      Human cancers are known to adhere to basic evolutionary principles. During their journey from early transformation to metastatic disease, cancer cell populations have proven to be remarkably adaptive to different forms of intra- and extracellular selective pressure, including nutrient scarcity, oxidative stress, and anti-cancer immunity. Adaption may be achieved via the expansion of clones bearing driver mutations that optimize cellular fitness in response to the specific selective scenario, e.g., mutations facilitating evasion of cell death, immune evasion or increased proliferation despite growth suppression, all of which constitute well-established hallmarks of cancer. While great progress concerning the prevention, diagnosis and treatment of clinically apparent disease has been made over the last 50 years, the mechanisms underlying cellular adaption under selective pressure via the immune system during early carcinogenesis and its influence on cancer cell fate or disease severity remain to be clarified. For instance, evasion of cell death is generally accepted as a hallmark of cancer, yet recent decades have revealed that the extrinsic cell death machinery triggered by immune effector cells is composed of an astonishingly complex network of interacting-and sometimes compensating-modes of cell death, whose role in selective processes during early carcinogenesis remains obscure. Based upon recent advances in cell death research, here we propose a concept of cell death pathway plasticity in time shaping cancer evolution prior to treatment in an effort to offer new perspectives on how cancer cell fate may be determined by cell death pathway plasticity during early carcinogenesis.