Promoter DNA methylation and transcription factor condensation are linked to transcriptional memory in mammalian cells.

The regulation of genes can be mathematically described by input-output functions that are typically assumed to be time invariant. This fundamental assumption underpins the design of synthetic gene circuits and the quantitative understanding of natural gene regulatory networks. Here, we found that this assumption is challenged in mammalian cells. We observed that a synthetic reporter gene can exhibit unexpected transcriptional memory, leading to a shift in the dose-response curve upon a second induction. Mechanistically, we investigated the cis-dependency of transcriptional memory, revealing the necessity of promoter DNA methylation in establishing memory. Furthermore, we showed that the synthetic transcription factor's effective DNA binding affinity underlies trans-dependency, which is associated with its capacity to undergo biomolecular condensation. These principles enabled modulating memory by perturbing either cis- or trans-regulation of genes. Together, our findings suggest the potential pervasiveness of transcriptional memory and implicate the need to model mammalian gene regulation with time-varying input-output functions. A record of this paper's transparent peer review process is included in the supplemental information.

In situ injectable hydrogel encapsulating Mn/NO-based immune nano-activator for prevention of postoperative tumor recurrence.

Postoperative tumor recurrence remains a predominant cause of treatment failure. In this study, we developed an in situ injectable hydrogel, termed MPB-NO@DOX + ATRA gel, which was locally formed within the tumor resection cavity. The MPB-NO@DOX + ATRA gel was fabricated by mixing a thrombin solution, a fibrinogen solution containing all-trans retinoic acid (ATRA), and a Mn/NO-based immune nano-activator termed MPB-NO@DOX. ATRA promoted the differentiation of cancer stem cells, inhibited cancer cell migration, and affected the polarization of tumor-associated macrophages. The outer MnO2 shell disintegrated due to its reaction with glutathione and hydrogen peroxide in the cytoplasm to release Mn2+ and produce O2, resulting in the release of doxorubicin (DOX). The released DOX entered the nucleus and destroyed DNA, and the fragmented DNA cooperated with Mn2+ to activate the cGAS-STING pathway and stimulate an anti-tumor immune response. In addition, when MPB-NO@DOX was exposed to 808 nm laser irradiation, the Fe-NO bond was broken to release NO, which downregulated the expression of PD-L1 on the surface of tumor cells and reversed the immunosuppressive tumor microenvironment. In conclusion, the MPB-NO@DOX + ATRA gel exhibited excellent anti-tumor efficacy. The results of this study demonstrated the great potential of in situ injectable hydrogels in preventing postoperative tumor recurrence.

Red blood cell membrane-coated functionalized Au nanocage as a biomimetic platform for improved MicroRNA delivery in hepatocellular carcinoma.

Dysregulation of microRNAs (miRNAs) expression is closely related to cancers and managing miRNA expression holds great promise for cancer therapy. However, their wide clinical application has been hampered by their poor stability, short half-life and non-specific biodistribution in vivo. Herein, a novel biomimetic platform designated as RHAuNCs-miRNA for improved miRNA delivery was prepared through wrapping miRNA-loaded functionalized Au nanocages (AuNCs) with red blood cell (RBC) membrane. RHAuNCs-miRNA not only successfully loaded miRNAs but also effectively protected them from enzymatic degradation. With good stability, RHAuNCs-miRNA had the characteristics of photothermal conversion and sustained release. Cellular uptake of RHAuNCs-miRNA by SMMC-7721 cells was in a time-dependent manner via clathrin- and caveolin-mediated endocytosis. The uptake of RHAuNCs-miRNAs was affected by cell types and improved by mild near infrared (NIR) laser irradiation. More importantly, RHAuNCs-miRNA exhibited a prolonged circulation time without the occurrence of accelerated blood clearance (ABC) in vivo, resulting in efficient delivery to tumor tissues. This study may demonstrate the great potential of RHAuNCs-miRNA for improved miRNAs delivery.

A robotic flexible endoscope with shared autonomy: a study of mockup cholecystectomy.

BACKGROUND: Endoscope is the eye of surgeon in minimally invasive surgery (MIS). Prevailing handheld endoscopes are manually steered, which can cause endoscope-instrument fencing. Robotic endoscopes can reduce the fatigue but could not reduce collisions. Handheld endoscopes with a flexible bending tip can reduce the shaft pivoting and collisions. However, its steering is challenging. In this paper, we present a robotic flexible endoscope with auto-tracking function and compare it with the conventional rigid endoscopes. METHODS: A robotic flexible endoscope (RFE) with shared autonomy is developed. The RFE could either track the instruments automatically or be controlled by a foot pedal. A mockup cholecystectomy was designed to evaluate the performance. Five surgeons were invited to perform the mockup cholecystectomy in an abdominal cavity phantom with a manual rigid endoscope (MRE), a robotic rigid endoscope (RRE), and the RFE. Space occupation, time consumption, and questionnaires based on the NASA task load index were adopted to evaluate the performances and compare the three endoscope systems. An ex vivo experiment was conducted to demonstrate the feasibility of using the RFE in a biological tissue environment. RESULTS: All surgeons completed the mockup cholecystectomy with the RFE independently. Failure occurred in the cases involving the RRE and the MRE. Inside the body cavity, the space occupied when using the RFE is 17.28% and 23.95% (p < 0.05) of that when using the MRE and the RRE, respectively. Outside the body cavity, the space occupied when using the RFE is 14.60% and 15.53% (p < 0.05) of that by using MRE and RRE. Time consumed in the operations with MRE, RRE, and RFE are 28.3 s, 93.2 s and 34.8 s, respectively. Questionnaires reveal that the performance of the RFE is the best among the three endoscope systems. CONCLUSIONS: The RFE provides a wider field of view (FOV) and occupies less space than rigid endoscopes.

A54 peptide-mediated functionalized gold nanocages for targeted delivery of DOX as a combinational photothermal-chemotherapy for liver cancer.

The combination of photothermal therapy and chemotherapy (photothermal-chemotherapy) is a promising strategy for cancer therapy. Gold nanocages (AuNCs), with hollow and porous structures and unique optical properties, have become a rising star in the field of drug delivery. Here, we designed a novel targeted drug delivery system based on functionalized AuNCs and evaluated their therapeutic effects in vitro and in vivo. We then loaded doxorubicin into this promising system, designated as DHTPAuNCs consisting of hyaluronic acid-grafted and A54 peptide-targeted PEGylated AuNCs. Its formation was corroborated by ultraviolet-visible spectroscopy, transmission electron microscopy and dynamic light scattering. This delivery platform needed hyaluronidase to release encapsulated drugs, meanwhile the acidic pH and near-infrared irradiation could accelerate the release. In addition, the results of cellular uptake demonstrate that this system could bind specifically with BEL-7402 cells. In vitro, we evaluated therapeutic effects of the DHTPAuNCs in BEL-7402 cells by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide assay. Moreover, in BEL-7402 tumor-bearing nude mice, its therapy effect in vivo was also evaluated. As expected, DHTPAuNCs exhibited excellent therapeutic effect by photothermal-chemotherapy, both in vitro and in vivo. In short, DHTPAuNCs with low toxicity showed great potential as a drug delivery system for cancer therapy.

Gold nanocages with dual modality for image-guided therapeutics.

Numerous studies have demonstrated that microRNAs are very important in cancer development and progression. However, the complex relationship between the size of microRNA delivery systems, cellular uptake, biodistribution and therapeutic efficiency remains unclear. Herein, we have successfully constructed a series of differently-sized microRNA delivery systems, miR-26a-loaded, hyaluronic acid-modified, polyetherimide-conjugated PEGylated gold nanocage ternary nanocomplexes (PPHAuNCs-TNCs), which can be monitored optically by fluorescence and photoacoustic tomography imaging. We evaluated the effect of the particle size on the cellular uptake and biodistribution in the BEL-7402 cell line in vitro and in the subcutaneous and orthotopic hepatocellular carcinoma (HCC) mouse models. Our findings showed that the cellular uptake and biodistribution were optimal for cancer therapy with the PPHAuNCs-30-TNCs (30 nm AuNCs in edge length) in comparison with their 50 nm and 70 nm counterparts. PPHAuNCs-30-TNCs could accumulate in the liver for a longer time in an orthotopic mouse model of HCC than that in normal mice and could considerably restrain tumor growth in an orthotopic HCC mouse model under near-infrared radiation. This study may provide insightful information for developing novel non-viral microRNA vectors, and PPHAuNCs-30-TNCs have great potential for application in tumor diagnosis and cancer therapy in the future.