NOP53 undergoes liquid-liquid phase separation and promotes tumor radio-resistance

Liquid-liquid phase separation in cell physiology and cancer biology: recent advances and therapeutic implications

Liquid-liquid phase separation (LLPS) is a pivotal biophysical phenomenon that plays a critical role in cellular organization and has garnered significant attention in the fields of molecular mechanism and pathophysiology of cancer. This dynamic process involves the spontaneous segregation of biomolecules, primarily proteins and nucleic acids, into condensed, liquid-like droplets under specific conditions. LLPS drives the formation of biomolecular condensates, which are crucial for various cellular functions. Increasing evidences link alterations in LLPS to the onset and progression of various diseases, particularly cancer. This review explores the diverse roles of LLPS in cancer, highlighting its underlying molecular mechanisms and far-reaching implications. We examine how dysregulated LLPS contributes to cancer development by influencing key processes such as genomic instability, metabolism, and immune evasion. Furthermore, we discuss emerging therapeutic strategies aimed at modulating LLPS, underscoring their potential to revolutionize cancer treatment.

PTK6 drives HNRNPH1 phase separation to activate autophagy and suppress apoptosis in colorectal cancer

Macroautophagy/autophagy is the principal mechanism that mediates the delivery of various cellular cargoes to lysosomes for degradation and recycling, and has been reported to play a crucial role in colorectal cancer (CRC) pathogenesis and progression. Targeting autophagy may be a promising therapeutic strategy for CRC. However, the specific functions and potential mechanisms of autophagy in CRC remain unclear. In the present study, we discovered that PTK6 (protein tyrosine kinase 6) could activate autophagy and inhibit CRC apoptosis. PTK6 physically interacted with HNRNPH1 and mediated tyrosine phosphorylation at Y210 of HNRNPH1, which promoted the latter's liquid-liquid phase separation (LLPS). Furthermore, LLPS of HNRNPH1 formed biomolecular condensates and triggered splicing-switching of the NBR1 exon 10 inclusion transcript, thereby activating autophagy and suppressing apoptosis of CRC. Additionally, PDO and CDX models indicated that tilfrinib, an inhibitor targeting PTK6, could inhibit CRC growth. Overall, our findings reveal the novel PTK6-HNRNPH1-NBR1 regulatory autophagy axis and provide a potential therapy target for CRC.Abbreviation: 1,6HD: 1,6-hexanediol, CQ: chloroquine, CRC: colorectal cancer, DFS: disease-free survival, FRAP: fluorescence recovery afterphotobleaching, GSEA: Gene Set Enrichment Analysis, GTEx: Genotype-Tissue Expression, HNRNPH1: heterogeneous nuclearribonucleoprotein H1, IDRs: intrinsically disordered regions, IHC: immunohistochemical, KEGG: Kyoto Encyclopedia of Genes and Genomes,LLPS: liquid-liquid phase separation, NBR1: NBR1 autophagy cargoreceptor, OS: overall survival, PDO: patient-derivedorganoid, PTK6: protein tyrosine kinase 6, PTMs: post-translationalmodifications, SE: skipped exon, TCGA: The Cancer Genome Atlas, TEM: transmission electron microscopy, TMA: tissue microarray, TyrKc: tyrosine kinase catalytic.

Phase separation in DNA double-strand break response

DNA double-strand break (DSB) is the most dangerous type of DNA damage, which may lead to cell death or oncogenic mutations. Homologous recombination (HR) and nonhomologous end-joining (NHEJ) are two typical DSB repair mechanisms. Recently, many studies have revealed that liquid-liquid phase separation (LLPS) plays a pivotal role in DSB repair and response. Through LLPS, the crucial biomolecules are quickly recruited to damaged sites with a high concentration to ensure DNA repair is conducted quickly and efficiently, which facilitates DSB repair factors activating downstream proteins or transmitting signals. In addition, the dysregulation of the DSB repair factor's phase separation has been reported to promote the development of a variety of diseases. This review not only provides a comprehensive overview of the emerging roles of LLPS in the repair of DSB but also sheds light on the regulatory patterns of phase separation in relation to the DNA damage response (DDR).

Phase separation in DNA damage response: New insights into cancer development and therapy

Phase separation, a process in which biomolecules segregate into distinct liquid-like compartments within cells, has recently been identified as a crucial regulator of various cellular functions, including the DNA damage response (DDR). Dysregulation of phase separation may contribute to genomic instability, oncogenesis, and tumor progression. However, the specific roles and mechanisms underlying phase separation remain largely elusive. This comprehensive review aims to elucidate the complex relationship between phase separation and the DDR in the context of cancer biology. We focus on the molecular mechanisms underlying phase separation and its role in orchestrating DDR signaling and repair processes. Additionally, we discuss how the dysregulation of phase separation in cancer cells impacts genome stability, tumorigenesis, and therapeutic responses. By leveraging the unique properties of phase separation in the DDR, researchers can potentially advance basic research and develop personalized cancer therapies targeting the dysregulated biomolecular condensates that drive tumorigenesis.

Role of liquid-liquid phase separation in cancer: Mechanisms and therapeutic implications

Liquid-liquid phase separation (LLPS) has emerged as a pivotal biological phenomenon involved in various cellular processes, including the formation of membrane-less organelles and the regulation of biomolecular condensates through precise spatiotemporal coordination of signaling pathways in cells. Dysregulation of LLPSs results in aberrant biomolecular condensates, which are widely implicated in tumorigenesis and cancer progression. Here, we comprehensively summarize the multifaceted roles of LLPS in tumor biology from the perspective of cancer hallmarks, including genomic stability, metabolic reprogramming progression, ferroptosis, and metastasis, to unveil the intricate mechanisms by which LLPS occurs in tumorigenesis. We discuss current discoveries related to therapeutic involvement and potential clinical applications of LLPS in cancer treatment, highlighting the potential of targeting LLPS-driven processes as novel therapeutic strategies. Additionally, we discuss the challenges associated with new approaches for cancer treatment based on LLPS. This in-depth discussion of the impact of LLPS on fundamental aspects of tumor biology provides new insights into overcoming cancer.

Ubiquitin-induced RNF168 condensation promotes DNA double-strand break repair

Rapid accumulation of repair factors at DNA double-strand breaks (DSBs) is essential for DSB repair. Several factors involved in DSB repair have been found undergoing liquid-liquid phase separation (LLPS) at DSB sites to facilitate DNA repair. RNF168, a RING-type E3 ubiquitin ligase, catalyzes H2A.X ubiquitination for recruiting DNA repair factors. Yet, whether RNF168 undergoes LLPS at DSB sites remains unclear. Here, we identified K63-linked polyubiquitin-triggered RNF168 condensation which further promoted RNF168-mediated DSB repair. RNF168 formed liquid-like condensates upon irradiation in the nucleus while purified RNF168 protein also condensed in vitro. An intrinsically disordered region containing amino acids 460-550 was identified as the essential domain for RNF168 condensation. Interestingly, LLPS of RNF168 was significantly enhanced by K63-linked polyubiquitin chains, and LLPS largely enhanced the RNF168-mediated H2A.X ubiquitination, suggesting a positive feedback loop to facilitate RNF168 rapid accumulation and its catalytic activity. Functionally, LLPS deficiency of RNF168 resulted in delayed recruitment of 53BP1 and BRCA1 and subsequent impairment in DSB repair. Taken together, our finding demonstrates the pivotal effect of LLPS in RNF168-mediated DSB repair.

JunB condensation attenuates vascular endothelial damage under hyperglycemic condition

Endothelial damage is the initial and crucial factor in the occurrence and development of vascular complications in diabetic patients, contributing to morbidity and mortality. Although hyperglycemia has been identified as a damaging effector, the detailed mechanisms remain elusive. In this study, identified by ATAC-seq and RNA-seq, JunB reverses the inhibition of proliferation and the promotion of apoptosis in human umbilical vein endothelial cells treated with high glucose, mainly through the cell cycle and p53 signaling pathways. Furthermore, JunB undergoes phase separation in the nucleus and in vitro, mediated by its intrinsic disordered region and DNA-binding domain. Nuclear localization and condensation behaviors are required for JunB-mediated proliferation and apoptosis. Thus, our study uncovers the roles of JunB and its coacervation in repairing vascular endothelial damage caused by high glucose, elucidating the involvement of phase separation in diabetes and diabetic endothelial dysfunction.

Interplay between posttranslational modifications and liquid‒liquid phase separation in tumors

Liquid‒liquid phase separation (LLPS) is a general phenomenon recently recognized to be critically involved in the regulation of a variety of cellular biological processes, such as transcriptional regulation, heterochromatin formation and signal transduction, through the compartmentalization of proteins or nucleic acids into droplet-like condensates. These processes are directly or indirectly related to tumor initiation and treatment. Posttranslational modifications (PTMs), which represent a rapid and reversible mechanism involved in the functional regulation of proteins, have emerged as key events in modulating LLPS under physiological or pathophysiological conditions, including tumorigenesis and antitumor therapy. In this review, we introduce the biological functions participated in cancer-associated LLPS, discuss the potential roles of LLPS during tumor onset or therapy, and emphasize the mechanistic characteristics of LLPS regulated by PTMs and its effects on tumor progression. We then provide a perspective on further studies on LLPS and its regulation by PTMs in cancer research. This review aims to broaden the understanding of the functions of LLPS and its regulation by PTMs under normal or aberrant cellular conditions.

CRDBP Protein Phase Separation and Its Recruitment to β-Catenin Protein in a Single Living Cell

The Coding Region Determinant-Binding Protein (CRDBP) is a carcinoembryonic protein, and it is overexpressed in various cancer cells in the form of granules. We speculated the formation of CRDBP granules possibly through liquid-liquid phase separation (LLPS) processes due to the existence of intrinsically disordered regions (IDRs) in CRDBP. So far, we did not know whether or how phase separation processes of CRDBP occur in single living cells due to the lack of in vivo methods for studying intracellular protein phase separation. Therefore, to develop an in situ method for studying protein phase separation in living cells is a very urgent task. In this work, we proposed an efficient method for studying phase separation behavior of CRDBP in a single living cell by combining in situ fluorescence correlation spectroscopy (FCS) and fluorescence cross-correlation spectroscopy (FCCS) with a fluorescence protein fusion technique. We first predicted and confirmed that CRDBP has phase separation in solution by conventional fluorescence imaging and FCS methods. And then, we in situ studied the phase separation behaviors of CRDBP in living cells and observed three states of CRDBP phase separation such as monomer state, cluster state, and granule state. We studied the effects of CRDBP truncated forms and its inhibitor on the CRDBP phase separation. Furthermore, we discovered the recruitment of CRDBP to β-catenin protein in living cells and investigated the effects of CRDBP structures and inhibitor on CRDBP recruitment behavior. This finding may help us to further understand the mechanism of CRDBP protein for regulating Wnt signaling pathway. Additionally, our results documented that FCS/FCCS is an efficient and alternative method for studying protein phase separation in situ in living cells.

The role of long noncoding RNAs in liquid-liquid phase separation

Long noncoding RNAs (lncRNAs), which are among the most well-characterized noncoding RNAs, have attracted much attention due to their regulatory functions and potential therapeutic options in many types of disease. Liquid-liquid phase separation (LLPS), the formation of droplet condensates, is involved in various cellular processes, but the molecular interactions of lncRNAs in LLPS are unclear. In this review, we describe the research development on LLPS, including descriptions of various methods established to identify LLPS, summarize the physiological and pathological functions of LLPS, identify the molecular interactions of lncRNAs in LLPS, and present the potential applications of leveraging LLPS in the clinic. The aim of this review is to update the knowledge on the association between LLPS and lncRNAs, which might provide a new direction for the treatment of LLPS-mediated disease.

Unraveling the function of epithelial-mesenchymal transition (EMT) in colorectal cancer: Metastasis, therapy response, and revisiting molecular pathways

Colorectal cancer (CRC) is a dangerous form of cancer that affects the gastrointestinal tract. It is a major global health concern, and the aggressive behavior of tumor cells makes it difficult to treat, leading to poor survival rates for patients. One major challenge in treating CRC is the metastasis, or spread, of the cancer, which is a major cause of death. In order to improve the prognosis for patients with CRC, it is necessary to focus on ways to inhibit the cancer's ability to invade and spread. Epithelial-mesenchymal transition (EMT) is a process that is linked to the spread of cancer cells, also known as metastasis. The process transforms epithelial cells into mesenchymal ones, increasing their mobility and ability to invade other tissues. This has been shown to be a key mechanism in the progression of colorectal cancer (CRC), a particularly aggressive form of gastrointestinal cancer. The activation of EMT leads to increases in the spread of CRC cells, and during this process, levels of the protein E-cadherin decrease while levels of N-cadherin and vimentin increase. EMT also contributes to the development of resistance to chemotherapy and radiation therapy in CRC. Non-coding RNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a role in regulating EMT in CRC, often through their ability to "sponge" microRNAs. Anti-cancer agents have been shown to suppress EMT and reduce the progression and spread of CRC cells. These findings suggest that targeting EMT or related mechanisms may be a promising approach for treating CRC patients in the clinic.