1,6-Hexanediol regulates angiogenesis via suppression of cyclin A1-mediated endothelial function

Apolipoprotein A-I Binding Protein Inhibits the Formation of Infantile Hemangioma through Cholesterol-Regulated Hypoxia-Inducible Factor 1α Activation

Infantile hemangioma (IH) is the most frequent vascular tumor of infancy with unclear pathogenesis; disordered angiogenesis is considered to be involved in its formation. Apolipoprotein A-I binding protein (AIBP)-also known as NAXE (NAD [P]HX epimerase)-a regulator of cholesterol metabolism, plays a critical role in the pathological angiogenesis of mammals. In this study, we found that AIBP had much lower expression levels in both tissues from patients with IH and hemangioma endothelial cells (HemECs) than in adjacent normal tissues and human dermal vascular endothelial cells, respectively. Knockout of NAXE by CRISPR-Cas9 in HemECs enhanced tube formation and migration, and NAXE overexpression impaired tube formation and migration of HemECs. Interestingly, AIBP suppressed the proliferation of HemECs in hypoxia. We then found that reduced expression of AIBP correlated with increased hypoxia-inducible factor 1α levels in tissues from patients with IH and HemECs. Further mechanistic investigation demonstrated that AIBP disrupted hypoxia-inducible factor 1α signaling through cholesterol metabolism under hypoxia. Notably, AIBP significantly inhibited the development of IH in immunodeficient mice. Furthermore, using the validated mouse endothelial cell (ie, EOMA cells) and Naxe-/- mouse models, we demonstrated that both endogenous AIBP from tumors and AIBP in the tumor microenvironment limit the formation of hemangioma. These findings suggested that AIBP was a player in the pathogenesis of IH and could be a potential pharmacological target for treating IH.

Phase separations in oncogenesis, tumor progressions and metastasis: a glance from hallmarks of cancer

Liquid-liquid phase separation (LLPS) is a novel principle for interpreting precise spatiotemporal coordination in living cells through biomolecular condensate (BMC) formation via dynamic aggregation. LLPS changes individual molecules into membrane-free, droplet-like BMCs with specific functions, which coordinate various cellular activities. The formation and regulation of LLPS are closely associated with oncogenesis, tumor progressions and metastasis, the specific roles and mechanisms of LLPS in tumors still need to be further investigated at present. In this review, we comprehensively summarize the conditions of LLPS and identify mechanisms involved in abnormal LLPS in cancer processes, including tumor growth, metastasis, and angiogenesis from the perspective of cancer hallmarks. We have also reviewed the clinical applications of LLPS in oncologic areas. This systematic summary of dysregulated LLPS from the different dimensions of cancer hallmarks will build a bridge for determining its specific functions to further guide basic research, finding strategies to intervene in LLPS, and developing relevant therapeutic approaches.

Rational therapeutic targets with biomolecular liquid-liquid phase separation regulating synergy: A pan-cancer analysis

Liquid-liquid phase separation (LLPS) is characterized as an ubiquitous framework for diverse biological processes including carcinogenesis and cancer progression. While targeting cancer from perspective of LLPS offers an opportunity to drug the conventionally undruggables with cancer-driving potential, the therapeutic value of cancer associated LLPS (CAL) proteins remains elusive. Here, we report the genomic landscape, prognostic relevance, immune-infiltration association, down-stream pathway alteration and small molecular responsiveness of CAL protein-coding gene signatures based on protein-coding associated mutations and transcriptional abundance in pan-cancer. Correlations of CAL protein-coding associated mutations and transcriptional abundances to overall survival and progression-free survival were observed in an array of cancers and further characterized by differential survival outcomes between patients with intrinsic disordered region (IDR) enriched and non-IDR enriched mutations in endometrial cancer. Altered signaling pathways and universal pattern of immune infiltrates on account of CAL protein-coding associated gene-set mutations involved key components of oncogenesis in various cancer types and well established therapeutic targets including MAPK signaling pathway and implied an inflamed tumor immunity that might be highly responsive to immunotherapy. LLPS inhibitor enhanced cytotoxicity of cisplatin/paclitaxel in selective cancer cell lines. These findings provide preliminary evidences for rational chemo-, targeted- and immuno-therapeutic innovation with LLPS regulating synergy.

RAP80 phase separation at DNA double-strand break promotes BRCA1 recruitment

RAP80 has been characterized as a component of the BRCA1-A complex and is responsible for the recruitment of BRCA1 to DNA double-strand breaks (DSBs). However, we and others found that the recruitment of RAP80 and BRCA1 were not absolutely temporally synchronized, indicating that other mechanisms, apart from physical interaction, might be implicated. Recently, liquid-liquid phase separation (LLPS) has been characterized as a novel mechanism for the organization of key signaling molecules to drive their particular cellular functions. Here, we characterized that RAP80 LLPS at DSB was required for RAP80-mediated BRCA1 recruitment. Both cellular and in vitro experiments showed that RAP80 phase separated at DSB, which was ascribed to a highly disordered region (IDR) at its N-terminal. Meanwhile, the Lys63-linked poly-ubiquitin chains that quickly formed after DSBs occur, strongly enhanced RAP80 phase separation and were responsible for the induction of RAP80 condensation at the DSB site. Most importantly, abolishing the condensation of RAP80 significantly suppressed the formation of BRCA1 foci, encovering a pivotal role of RAP80 condensates in BRCA1 recruitment and radiosensitivity. Together, our study disclosed a new mechanism underlying RAP80-mediated BRCA1 recruitment, which provided new insight into the role of phase separation in DSB repair.