Smad nuclear-interacting protein 1 (SNIP1) is a transcription repressor related to the TGF-β signaling pathway and associates with c-MYC, a key regulator of cell proliferation and tumor development. Currently, the mechanism by which SNIP1 regulates tumorigenesis and cancer metastasis is unknown. Here, we identify that SNIP1 is a non-histone substrate of lysine methyltransferase KMT5A, which undergoes KMT5A-mediated mono-methylation to promote breast cancer cell growth, invasion and lung metastasis. Mechanistically, we show KMT5A-mediated K301 methylation of SNIP1 represents a sensing signal to release histone acetyltransferase KAT2A and promotes the interaction of c-MYC and KAT2A, and the recruitment of c-MYC/KAT2A complex to promoter of c-MYC targets. This event ultimately inhibits the Hippo kinase cascade to enhance triple-negative breast cancer (TNBC) metastasis by transcriptionally activating MARK4. Co-inhibition of KMT5A catalytic activity and YAP in TNBC xenograft-bearing animals attenuates breast cancer metastasis and increases survival. Collectively, this study presents an KMT5A methylation-dependent regulatory mechanism governing oncogenic function of SNIP1.

The microenvironment of lymph node metastasized tumors (LNMT) determines tumor progression and response to therapy, but a systematic study of LNMT is lacking. Here, we generate single-cell maps of primary tumors (PTs) and paired LNMTs in 8 breast cancer patients. We demonstrate that the activation, cytotoxicity, and proliferation of T cells are suppressed in LNMT compared with PT. CD4+CXCL13+ T cells in LNMT are more likely to differentiate into an exhausted state. Interestingly, LAMP3+ dendritic cells in LNMT display lower T cell priming and activating ability than in PT. Additionally, we identify a subtype of PLA2G2A+ cancer-associated fibroblasts enriched in HER2+ breast cancer patients that promotes immune infiltration. We also show that the antigen-presentation pathway is downregulated in malignant cells of the metastatic lymph node. Altogether, we characterize the microenvironment of LNMT and PT, which may shed light on the individualized therapeutic strategies for breast cancer patients with lymph node metastasis.

The immediate processing of whole blood specimen is required in circulating tumor cell-based liquid biopsy. Reliable blood specimen stabilization towards preserving circulating tumor cells can enable more extensive geographic sharing for precise rare-cell technology, but remains challenging due to the fragility and rarity of circulating tumor cells. Herein, we establish a zwitterionic magnetic microgel platform to stabilize whole blood specimen for long-term hypothermic preservation of model circulating tumor cells. We show in a cohort study of 20 cancer patients that blood samples can be preserved for up to 7 days without compromising circulating tumor cell viability and RNA integrity, thereby doubling the viable preservation duration. We demonstrate that the 7-day microgel-preserved blood specimen is able to reliably detect cancer-specific transcripts, similar to fresh blood specimens, while there are up/down expression regulation of 1243 genes in model circulating tumor cells that are preserved by commercial protectant. Mechanistically, we find that the zwitterionic microgel assembly counters the cold-induced excessive reactive oxygen species and platelet activation, as well as extracellular matrix loss-induced cell anoikis, to prevent circulating tumor cell loss in the whole blood sample. The present work could prove useful for the development of blood-based noninvasive diagnostics.

The methyltransferase like 3 (METTL3) has been generally recognized as a nuclear protein bearing oncogenic properties. We find predominantly cytoplasmic METTL3 expression inversely correlates with node metastasis in human cancers. It remains unclear if nuclear METTL3 is functionally distinct from cytosolic METTL3 in driving tumorigenesis and, if any, how tumor cells sense oncogenic insults to coordinate METTL3 functions within these intracellular compartments. Here, we report an acetylation-dependent regulation of METTL3 localization that impacts on metastatic dissemination. We identify an IL-6-dependent positive feedback axis to facilitate nuclear METTL3 functions, eliciting breast cancer metastasis. IL-6, whose mRNA transcript is subjected to METTL3-mediated m6A modification, promotes METTL3 deacetylation and nuclear translocation, thereby inducing global m6A abundance. This deacetylation-mediated nuclear shift of METTL3 can be counterbalanced by SIRT1 inhibition, a process that is further enforced by aspirin treatment, leading to ablated lung metastasis via impaired m6A methylation. Intriguingly, acetylation-mimetic METTL3 mutant reconstitution results in enhanced translation and compromised metastatic potential. Our study identifies an acetylation-dependent regulatory mechanism determining the subcellular localization of METTL3, which may provide mechanistic clues for developing therapeutic strategies to combat breast cancer metastasis.

Anti-cancer immunity and response to immune therapy is influenced by the metabolic states of the tumours. Immune checkpoint blockade therapy (ICB) is known to involve metabolic adaptation, however, the mechanism is not fully known. Here we show, by metabolic profiling of plasma samples from melanoma-bearing mice undergoing anti-PD1 and anti-CTLA4 combination therapy, that higher levels of purine metabolites, including inosine, mark ICB sensitivity. Metabolic profiles of ICB-treated human cancers confirm the association between inosine levels and ICB sensitivity. In mouse models, inosine supplementation sensitizes tumours to ICB, even if they are intrinsically ICB resistant, by enhancing T cell-mediated cytotoxicity and hence generating an immunologically hotter microenvironment. We find that inosine directly inhibits UBA6 in tumour cells, and lower level of UBA6 makes the tumour more immunogenic and this is reflected in favourable outcome following ICB therapy in human melanomas. Transplanted mouse melanoma and breast cancer cells with genetic ablation of Uba6 show higher sensitivity to ICB than wild type tumours. Thus, we provide evidence of an inosine-regulated UBA6-dependent pathway governing tumour-intrinsic immunogenicity and hence sensitivity to immune checkpoint inhibition, which might provide targets to overcome ICB resistance.

Diagnostic and therapeutic illumination on internal organs and tissues with high controllability and adaptability in terms of spectrum, area, depth, and intensity remains a major challenge. Here, we present a flexible, biodegradable photonic device called iCarP with a micrometer scale air gap between a refractive polyester patch and the embedded removable tapered optical fiber. ICarP combines the advantages of light diffraction by the tapered optical fiber, dual refractions in the air gap, and reflection inside the patch to obtain a bulb-like illumination, guiding light towards target tissue. We show that iCarP achieves large area, high intensity, wide spectrum, continuous or pulsatile, deeply penetrating illumination without puncturing the target tissues and demonstrate that it supports phototherapies with different photosensitizers. We find that the photonic device is compatible with thoracoscopy-based minimally invasive implantation onto beating hearts. These initial results show that iCarP could be a safe, precise and widely applicable device suitable for internal organs and tissue illumination and associated diagnosis and therapy.