Exosomes-delivered PD-L1 siRNA and CTLA-4 siRNA protect against growth and tumor immune escape in colorectal cancer.

OBJECTIVE: This study aims to dissect impacts of exosomes-delivered PD-L1 and CTLA-4 siRNAs on colorectal cancer (CRC) progression and immune responses. METHODS: Exosomes containing PD-L1 siRNA and CTLA-4 siRNA were prepared and utilized to treat CRC cells to evaluate their effects. A tumor-bearing mouse model was established for verification. RESULTS: Exosomes containing PD-L1 siRNA and CTLA-4 siRNA repressed malignant features of CRC cells and restrained tumor growth and activated tumor immune responses in vivo. Co-culture of CRC cells treated with exosomes containing PD-L1 siRNA and CTLA-4 siRNA with human CD8+ T cells increased the percentage of CD8+ T cells, decreased the apoptotic rate of CD8+ T cells, elevated IL-2, IFN-γ, and TNF-α expression in cell supernatants, reduced adherent density of CRC cells, augmented the positive rate of CRC cells, and subdued tumor immune escape. CONCLUSION: Exosomes containing PD-L1 siRNA and CTLA-4 siRNA suppressed CRC progression and enhanced tumor immune responses.

The mechanisms underlying the enrichment and action of glypican-1-positive exosomes in colorectal cancer cells.

BACKGROUND: Glypican-1 (GPC1) is overexpressed in several tumors, and GPC1+ exosomes have shown the potential to predict early colorectal cancer (CRC). However, the mechanisms underlying the enrichment and action of GPC1+ exosomes in CRC remain unknown. METHODS: The expression of slit guidance ligand 2 (SLIT2), hypoxia-inducible factor (HIF)-1α/2α, and GPC1 in clinical CRC tissues was detected using immunohistochemistry and western blot. Exosomes were isolated from the supernatants of CRC cell cultures. The effects of SLIT2, hypoxia, heparin, and phospholipase C (PLC) on exosomal GPC1 expression and GPC1+ exosome enrichment in CRC cells were analyzed with western blot and flow cytometry. CRC cell proliferation was assessed with MTT and colony formation assays. Co-immunoprecipitation was used to detect the binding of GPC1 and SLIT2 in SW480 cells. Nude mice were subcutaneously inoculated with SW480 cells with different treatments. The Wnt signaling was detected. RESULTS: SLIT2 was poorly expressed and GPC1, HIF-1α, and HIF-2α were highly expressed in human CRC tissues. SLIT2 in CRC cells inhibited GPC1+ exosome enrichment and exosomal GPC1 expression. PLC and heparin increased GPC1+ exosome enrichment in CRC cells in a concentration-dependent manner. Hypoxia increased the enrichment of GPC1+ exosomes in CRC cells depending on HIF-2α expression. GPC1+ exosomes stimulated CRC cell proliferation and xenograft tumor growth through activation of Wnt signaling. CONCLUSIONS: GPC1+ exosome enrichment is related to PLC and heparin. Hypoxia increases the enrichment of GPC1+ exosomes in CRC cells by activating HIF-2α and downregulating SLIT2. GPC1+ exosomes further drive CRC progression by activating Wnt signaling.

Complete Tri-Axis Magnetometer Calibration with a Gyro Auxiliary.

Magnetometers combined with inertial sensors are widely used for orientation estimation, and calibrations are necessary to achieve high accuracy. This paper presents a complete tri-axis magnetometer calibration algorithm with a gyro auxiliary. The magnetic distortions and sensor errors, including the misalignment error between the magnetometer and assembled platform, are compensated after calibration. With the gyro auxiliary, the magnetometer linear interpolation outputs are calculated, and the error parameters are evaluated under linear operations of magnetometer interpolation outputs. The simulation and experiment are performed to illustrate the efficiency of the algorithm. After calibration, the heading errors calculated by magnetometers are reduced to 0.5° (1σ). This calibration algorithm can also be applied to tri-axis accelerometers whose error model is similar to tri-axis magnetometers.