Transmembrane nuclease NUMEN/ENDOD1 regulates DNA repair pathway choice at the nuclear periphery.

Proper repair of DNA damage lesions is essential to maintaining genome integrity and preventing the development of human diseases, including cancer. Increasing evidence suggests the importance of the nuclear envelope in the spatial regulation of DNA repair, although the mechanisms of such regulatory processes remain poorly defined. Through a genome-wide synthetic viability screen for PARP-inhibitor resistance using an inducible CRISPR-Cas9 platform and BRCA1-deficient breast cancer cells, we identified a transmembrane nuclease (renamed NUMEN) that could facilitate compartmentalized and non-homologous end joining-dependent repair of double-stranded DNA breaks at the nuclear periphery. Collectively, our data demonstrate that NUMEN generates short 5' overhangs through its endonuclease and 3'→5' exonuclease activities, promotes the repair of DNA lesions-including heterochromatic lamina-associated domain breaks as well as deprotected telomeres-and functions as a downstream effector of DNA-dependent protein kinase catalytic subunit. These findings underline the role of NUMEN as a key player in DNA repair pathway choice and genome-stability maintenance, and have implications for ongoing research into the development and treatment of genome instability disorders.

Tumor Microenvironment Mediated Spermidine-Metal-Immunopeptide Nanocomplex for Boosting Ferroptotic Immunotherapy of Lymphoma.

Immunotherapy as an alternative treatment strategy for B-cell lymphoma is undesirable because of tumor heterogeneity and immune surveillance. Spermidine (SPM), as a regulator of the tumor microenvironment (TME), can facilitate the release of damage-associated molecular patterns (DAMPs) from cancer cells, promote immune recognition, and thus alleviate immune surveillance in the TME. Hence, in this work, self-assembled spermidine-based metal-immunopeptide nanocomplexes (APP-Fe NCs; APP is anti-programmed death ligand-1 peptide) with pH-responsive release kinetics were prepared via the flash nanocomplexation (FNC) technique based on the noncovalent interaction between APP-SPM-dextran (DEX) and sodium tripolyphosphate (TPP) and coordination between Fe3+ and TPP. An in vitro study suggested that APP-Fe NCs effectively induce strong oxidative stress and mitochondrial dysfunction and subsequently lead to ferroptosis in cells by interfering with homeostasis in lymphoma cells. Further investigation on lymphoma mice models demonstrated that APP-Fe NCs effectively inhibited the growth and liver metastasis of lymphomas. Mechanistically, by triggering ferroptosis in tumor tissues, these spermidine-containing APP-Fe NCs efficiently facilitated the release of DAMPs and ultimately reshaped TME to enhance immunotherapy efficacy in lymphoma. Combined with its good histocompatibility and facile preparation technique, this pH-responsive APP-Fe NCs with regulation on TME may hold potential for cascade amplification on the combinative immunotherapy of lymphoma in the clinic.

Pan-cancer investigation of C-to-U editing reveals its important role in cancer development and new targets for cancer treatment.

RNA editing is prevalent in the transcriptome and is important for multiple cellular processes. C-to-U RNA editing sites (RES) are relatively rare and understudied in humans, compared to A-to-I editing. However, the functional impact of C-to-U editing in human cancers also remains elusive. Here, we conducted the first comprehensive survey of pan-cancer C-to-U RESs. Surprisingly, we found that the same subset of RESs were associated with multiple features, including patient survival, cancer stemness, tumor mutation burden (TMB), and tumor-infiltrated immune cell compositions (ICC), suggesting an RES-mediated close relationship between these features. For example, editing sites for GALM or IFI6 that led to higher expression were linked to lower survival and more cancer stemness. Also, TMB was found to be lower in prostate cancer cases with ICC-associated RESs in CAVIN1 or VWA8 or higher in prostate cancer cases with thymoma. With experimental support, we also found RESs in CST3, TPI1, or TNC that are linked to immune checkpoint blockade by anti-PD1. We also confirmed through experiments that two C-to-U RESs in CSNK2B or RPS14 had different effects on colon cancer cells. Patients with CSNK2B editing, which increased the expression of the oncogene CLDN18, had a lower response to drugs. On the other hand, drugs worked better on people who had RPS14 editing, which greatly increased ribosome production. In summary, our study demonstrated the important roles of C-to-U RESs across cancers and shed light on personalized cancer therapy.

Distinct dosage compensations of ploidy-sensitive and -insensitive X chromosome genes during development and in diseases.

The active X chromosome in mammals is upregulated to balance its dosage to autosomes during evolution. However, it is elusive why the known dosage compensation machinery showed uneven and small influence on X genes. Here, based on >20,000 transcriptomes, we identified two X gene groups (ploidy-sensitive [PSX] and ploidy-insensitive [PIX]), showing distinct but evolutionarily conserved dosage compensations (termed XAR). We demonstrated that XAR-PIX was downregulated whereas XAR-PSX upregulated at both RNA and protein levels across cancer types, in contrast with their trends during stem cell differentiation. XAR-PIX, but not XAR-PSX, was lower and correlated with autoantibodies and inflammation in patients of lupus, suggesting that insufficient dosage of PIX genes contribute to lupus pathogenesis. We further identified and experimentally validated two XAR regulators, TP53 and ATRX. Collectively, we provided insights into X dosage compensation in mammals and demonstrated different regulation of PSX and PIX and their pathophysiological roles in human diseases.

Redox-responsive self-assembled polymeric nanoprodrug for delivery of gemcitabine in B-cell lymphoma therapy.

Gemcitabine, as a standard and classic strategy for B-cell lymphoma in the clinic, is limited by its poor pharmacodynamics. Although stimuli-responsive polymeric nanodelivery systems have been widely investigated in the past decade, issues such as complicated procedures, low loading capacity, and uncontrollable release kinetics still hinder their clinical translation. In view of the above considerations, we attempt to construct hyperbranched polyprodrug micelles with considerable drug loading via simple procedures and make use of the particularity of the tumor microenvironment to ensure that the micelles are "inactivated" in normal tissues and "activated" in the tumor microenvironment. Hence, in this work, a redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) with considerable loading capacity (≈ 24.6%) exhibited on-demand and accurate control of gemcitabine release under a simulated tumor microenvironment and thus significantly induced the apoptosis of B-cell lymphoma in vitro. Moreover, in the A20 tumor xenograft murine model, GSP NPs efficiently decreased the expansion of tumor tissues with minimal systemic toxicity. In summary, these redox-responsive and self-assembling GSP NPs with a facile one-pot synthesis procedure may hold great potency in clinical translation for enhanced chemotherapy of B-cell lymphoma. STATEMENT OF SIGNIFICANCE: A redox-responsive polymeric gemcitabine-prodrug (GEM-S-S-PEG) was one-pot synthesized via facile esterification and acylation. The self-assembled subsize (< 100 nm) GEM-S-S-PEG (GSP NPs) exhibited significant tumor therapeutic effects in vitro and in vivo. The polyprodrug GEM-S-S-PEG prepared in this study shows the great potential of redox-responsive nanodrugs for antitumor activity, which provides a reference value for the optimization of the design of functional polyprodrugs.

A lysosome-targeted dextran-doxorubicin nanodrug overcomes doxorubicin-induced chemoresistance of myeloid leukemia.

The hypoxic microenvironment is presumed to be a sanctuary for myeloid leukemia cells that causes relapse following chemotherapy, but the underlying mechanism remains elusive. Using a zebrafish xenograft model, we observed that the hypoxic hematopoietic tissue preserved most of the chemoresistant leukemic cells following the doxorubicin (Dox) treatment. And hypoxia upregulated TFEB, a master regulator of lysosomal biogenesis, and increased lysosomes in leukemic cells. Specimens from relapsed myeloid leukemia patients also harbored excessive lysosomes, which trapped Dox and prevented drug nuclear influx leading to leukemia chemoresistance. Pharmaceutical inhibition of lysosomes enhanced Dox-induced cytotoxicity against leukemic cells under hypoxia circumstance. To overcome lysosome associated chemoresistance, we developed a pH-sensitive dextran-doxorubicin nanomedicine (Dex-Dox) that efficiently released Dox from lysosomes and increased drug nuclear influx. More importantly, Dex-Dox treatment significantly improved the chemotherapy outcome in the zebrafish xenografts transplanted with cultured leukemic cells or relapsed patient specimens. Overall, we developed a novel lysosome targeting nanomedicine that is promising to overcome the myeloid leukemia chemoresistance.