Dual-Epigenetically Relieving the MYC-Correlated Immunosuppression via an Advanced Nano-Radiosensitizer Potentiates Cancer Immuno-Radiotherapy

Cancer cells can upregulate the MYC expression to repair the radiotherapy-triggered DNA damage, aggravating therapeutic resistance and tumor immunosuppression. Epigenetic treatment targeting the MYC-transcriptional abnormality may intensively solve this clinical problem. Herein, 5-Aza (a DNA methyltransferase inhibitor) and ITF-2357 (a histone deacetylase inhibitor) are engineered into a tungsten-based nano-radiosensitizer (PWAI), to suppress MYC rising and awaken robust radiotherapeutic antitumor immunity. Individual 5-Aza depletes MYC expression but cannot efficiently awaken radiotherapeutic immunity. This drawback can be overcome by the addition of ITF-2357, which triggers cancer cellular type I interferon (IFN-I) signaling. Coupling 5-Aza with ITF-2357 ensures that PWAI does not evoke the treated model with high MYC-related immune resistance while amplifying the radiotherapeutic tumor killing, and more importantly promotes the generation of IFN-I signal-related proteins involving IFN-α and IFN-β. Unlike the radiation treatment alone, PWAI-triggered immuno-radiotherapy remarkably enhances antitumor immune responses involving the tumor antigen presentation by dendritic cells, and improves intratumoral recruitment of cytotoxic T lymphocytes and their memory-phenotype formation in 4T1 tumor-bearing mice. Downgrading the radiotherapy-induced MYC overexpression via the dual-epigenetic reprogramming strategy may elicit a robust immuno-radiotherapy.

Shear Stress Drives the Cleavage Activation of Protease-Activated Receptor 2 by PRSS3/Mesotrypsin to Promote Invasion and Metastasis of Circulating Lung Cancer Cells

When circulating tumor cells (CTCs) travel in circulation, they can be killed by detachment-induced anoikis and fluidic shear stress (SS)-mediated apoptosis. Circulatory treatment, which can make CTCs detached but also generate SS, can increase metastasis of cancer cells. To identify SS-specific mechanosensors without detachment impacts, a microfluidic circulatory system is used to generate arteriosus SS and compare transcriptome profiles of circulating lung cancer cells with suspended cells. Half of the cancer cells can survive SS damage and show higher invasion ability. Mesotrypsin (PRSS3), protease-activated receptor 2 (PAR2), and the subunit of activating protein 1, Fos-related antigen 1 (FOSL1), are upregulated by SS, and their high expression is responsible for promoting invasion and metastasis. SS triggers PRSS3 to cleave the N-terminal inhibitory domain of PAR2 within 2 h. As a G protein-coupled receptor, PAR2 further activates the Gαi protein to turn on the Src-ERK/p38/JNK-FRA1/cJUN axis to promote the expression of epithelial-mesenchymal transition markers, and also PRSS3, which facilitates metastasis. Enriched PRSS3, PAR2, and FOSL1 in human tumor samples and their correlations with worse outcomes reveal their clinical significance. PAR2 may serve as an SS-specific mechanosensor cleavable by PRSS3 in circulation, which provides new insights for targeting metastasis-initiating CTCs.