A novel protein encoded by circINSIG1 reprograms cholesterol metabolism by promoting the ubiquitin-dependent degradation of INSIG1 in colorectal cancer.

BACKGROUND: Hypoxia is a hallmark of solid tumors and leads to the metabolic reprogramming of cancer cells. The role of epigenetic regulation between hypoxia and aberrant cholesterol metabolism in colorectal cancer (CRC) remains elusive. METHODS: Hypoxia-responsive circular RNAs (circRNAs) were identified by high throughput RNA sequencing between CRC cells cultured under normoxia or hypoxia. The protein-coding potential of circINSIG1 was identified by polysome profiling and LC-MS. The function of circINSIG1 was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by immunoprecipitation analyses. RESULTS: A novel hypoxia-responsive circRNA named circINSIG1 was identified, which was upregulated in CRC tissues and correlated with advanced clinical stages and poor survival. Mechanistically, circINSIG1 encoded a 121 amino acid protein circINSIG1-121 to promote K48-linked ubiquitination of the critical cholesterol metabolism regulator INSIG1 at lysine 156 and 158 by recruiting CUL5-ASB6 complex, a ubiquitin E3 ligase complex, thereby inducing cholesterol biosynthesis to promote CRC proliferation and metastasis. The orthotopic xenograft tumor models and patient-derived xenograft models further identified the role of circINSIG1 in CRC progression and potential therapeutic target of CRC. CONCLUSIONS: circINSIG1 presents an epigenetic mechanism which provides insights into the crosstalk between hypoxia and cholesterol metabolism, and provides a promising therapeutic target for the treatment of CRC.

A novel NF-κB regulator encoded by circPLCE1 inhibits colorectal carcinoma progression by promoting RPS3 ubiquitin-dependent degradation.

BACKGROUND: Constitutive activation of nuclear factor-κB (NF-κB) signaling plays a key role in the development and progression of colorectal carcinoma (CRC). However, the underlying mechanisms of excessive activation of NF-κB signaling remain largely unknown. METHODS: We used high throughput RNA sequencing to identify differentially expressed circular RNAs (circRNAs) between normal human intestinal epithelial cell lines and CRC cell lines. The identification of protein encoded by circPLCE1 was performed using LC-MS. The function of novel protein was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by immunoprecipitation analyses. RESULTS: A novel protein circPLCE1-411 encoded by circular RNA circPLCE1 was identified as a crucial player in the NF-κB activation of CRC. Mechanistically, circPLCE1-411 promoted the ubiquitin-dependent degradation of the critical NF-κB regulator RPS3 via directly binding the HSP90α/RPS3 complex to facilitate the dissociation of RPS3 from the complex, thereby reducing NF-κB nuclear translocation in CRC cells. Functionally, circPLCE1 inhibited tumor proliferation and metastasis in CRC cells, as well as patient-derived xenograft and orthotopic xenograft tumor models. Clinically, circPLCE1 was downregulated in CRC tissues and correlated with advanced clinical stages and poor survival. CONCLUSIONS: circPLCE1 presents an epigenetic mechanism which disrupts NF-κB nuclear translocation and serves as a novel and promising therapeutic target and prognostic marker.

A comprehensive overview of Artemisinin and its derivatives as anticancer agents.

Artemisinin is the crucial ingredient of artemisia annua, a traditional Chinese medicine used for the therapy of malaria in China for hundreds of years. In recent years, the anticancer properties of artemisinin and its derivatives have also been reported. This review has summarized the research and development of artemisinin and its derivatives as anticancer agents, which included both natural and synthetic monomers as well as their dimers. In addition, it highlights the antitumor effects of artemisinin and its derivatives after site-modification or after transformation to a nano-delivery system. Moreover, we have further explored their potential mechanisms of action and also discussed the clinical trials of ARTs used to treat cancer, which will facilitate in further development of novel anticancer drugs based on the scaffold of artemisinin.

GAS6 From CD200+ Adipose-Derived Stem Cells Mitigates Colonic Inflammation in a Macrophage-Dependent Manner.

BACKGROUND AND AIMS: Stem cell therapy is a promising cell-based treatment modality for inflammatory bowel diseases [IBD], but its application is limited by the nature of cell heterogeneity. METHODS: Single-cell RNA-sequencing was performed on the adipose-derived stem cells [ADSCs]. The in vitro immunomodulatory effect of ADSCs was evaluated by co-culturing with human CD4+ T cells or macrophages. The in vivo therapeutic value of ADSCs was assessed using a murine colitis model induced by dextran sulphate sodium [DSS] or 2,4,6-trinitrobenzene sulphonic acid [TNBS]. RESULTS: CD200+ ADSCs were identified as a novel subpopulation of ADSCs, based on gene ontology analysis of immunoregulatory functions. The immunoregulatory functions of these cells were further confirmed by co-culturing with CD4+ T cells or macrophages. Administration of CD200+ ADSCs effectively reduced intestinal inflammation in IBD mice models. Furthermore, we found CD200+ ADSCs-derived GAS6 exerted protective effects on experimental colitis by promoting macrophage M2 polarization via the Mer/PI3K/Akt/GSK3ß signalling pathway. CONCLUSIONS: This study uncovered the heterogeneity in ADSCs, in which CD200+ ADSCs presents as an alternative to conventional treatment of IBD.

Facilitated Drug Repurposing with Artemisinin-Derived PROTACs: Unveiling PCLAF as a Therapeutic Target.

Artemisinin, a prominent anti-malaria drug, is being investigated for its potential as a repurposed cancer treatment. However, its effectiveness in tumor cell lines remains limited, and its mechanism of action is unclear. To make more progress, the PROteolysis-TArgeting chimera (PROTAC) technique has been applied to design and synthesize novel artemisinin derivatives in this study. Among them, AD4, the most potent compound, exhibited an IC50 value of 50.6 nM in RS4;11 cells, over 12-fold better than that of its parent compound, SM1044. This was supported by prolonged survival of RS4;11-transplanted NOD/SCID mice. Meanwhile, AD4 effectively degraded PCLAF in RS4;11 cells and thus activated the p21/Rb axis to exert antitumor activity by directly targeting PCLAF. The discovery of AD4 highlights the great potential of using PROTACs to improve the efficacy of natural products, identify therapeutic targets, and facilitate drug repurposing. This opens a promising avenue for transforming other natural products into effective therapies.

Transanal total mesorectal excision combined with intersphincteric resection has similar long-term oncological outcomes to laparoscopic abdominoperineal resection in low rectal cancer: a propensity score-matched cohort study.

Background: Transanal total mesorectal excision (taTME) or intersphincteric resection (ISR) has recently proven to be a valid and safe surgical procedure for low rectal cancer. However, studies focusing on the combination of these two technologies are limited. This study aimed to evaluate perioperative results, long-term oncologic outcomes, and anorectal functions of patients with low rectal cancer undergoing taTME combined with ISR, by comparing with those of patients undergoing laparoscopic abdominoperineal resection (laAPR). Methods: After 1:1 propensity score matching, 200 patients with low rectal cancer who underwent laAPR (n = 100) or taTME combined with ISR (n = 100) between September 2013 and November 2019 were included. Patient demographics, clinicopathological characteristics, oncological outcomes, and anal functional results were analysed. Results: Patients in the taTME-combined-with-ISR group had less intraoperative blood loss (79.6 ± 72.6 vs 107.3 ± 65.1 mL, P = 0.005) and a lower rate of post-operative complications (22.0% vs 44.0%, P < 0.001) than those in the laAPR group. The overall local recurrence rates were 7.0% in both groups within 3 years after surgery. The 3-year disease-free survival rates were 86.3% in the taTME-combined-with-ISR group and 75.1% in the laAPR group (P = 0.056), while the 3-year overall survival rates were 96.7% and 94.2%, respectively (P = 0.319). There were 39 patients (45.3%) in the taTME-combined-with-ISR group who developed major low anterior resection syndrome, whereas 61 patients (70.9%) had good post-operative anal function (Wexner incontinence score ≤ 10). Conclusion: We found similar long-term oncological outcomes for patients with low rectal cancer undergoing laAPR and those undergoing taTME combined with ISR. Patients receiving taTME combined with ISR had acceptable post-operative anorectal function.

Puerarin Protects Against LPS-Induced Vascular Endothelial Cell Hyperpermeability via Preventing Downregulation of Endothelial Cadherin.

In the present study, we aimed to investigate the effects of puerarin on the hyperpermeability of vascular endothelial cells induced by lipopolysaccharide (LPS) and its underlying mechanisms. Human umbilical vein endothelial cells (HUVECs) were pre-incubated with puerarin (25, 50, and 100 µM) for 1 h, and then exposed to LPS (1 µg/mL). The monolayer permeability of endothelial cells was assessed by measuring the paracellular flux of FITC-dextran 40,000 (FD40). The expression of vascular endothelial cadherin (VE-cadherin) in HUVECs was examined by Western blotting analysis. A total of 18 mice were randomly assigned into three groups as follows: control group, LPS group, and puerarin group. The pulmonary W/D ratio (wet-to-dry weight ratios) was calculated, and the lung morphology was examined. The levels of TNF-α and IL-1ß in cell supernatant and mouse serum were determined by ELISA. Compared with the control group, LPS obviously increased the flux of FD40 and the monolayer permeability, raised the levels of TNF-α and IL-1ß in cell supernatant, and reduced the VE-cadherin expression in HUVECs. However, puerarin (25, 50, and 100 µM) was able to relieve such LPS-induced increase in flux of FD40 and then reduce the hyperpermeability. Puerarin decreased the levels of TNF-α and IL-1ß in cell supernatant and increased the VE-cadherin expression in HUVECs (P < 0.05). Moreover, LPS obviously increased the levels of TNF-α and IL-1ß in mouse serum and elevated the pulmonary W/D ratios, resulting in lung injury. However, all of above-mentioned LPS-induced changes were improved by puerarin pre-treatment. Puerarin could alleviate LPS-induced hyperpermeability in endothelial cells via preventing downregulation of endothelial cadherin.