PROTAC-Mediated HDAC7 Protein Degradation Unveils Its Deacetylase-Independent Proinflammatory Function in Macrophages.

Class IIa histone deacetylases (Class IIa HDACs) play critical roles in regulating essential cellular metabolism and inflammatory pathways. However, dissecting the specific roles of each class IIa HDAC isoform is hindered by the pan-inhibitory effect of current inhibitors and a lack of tools to probe their functions beyond epigenetic regulation. In this study, a novel PROTAC-based compound B4 is developed, which selectively targets and degrades HDAC7, resulting in the effective attenuation of a specific set of proinflammatory cytokines in both lipopolysaccharide (LPS)-stimulated macrophages and a mouse model. By employing B4 as a molecular probe, evidence is found for a previously explored role of HDAC7 that surpasses its deacetylase function, suggesting broader implications in inflammatory processes. Mechanistic investigations reveal the critical involvement of HDAC7 in the Toll-like receptor 4 (TLR4) signaling pathway by directly interacting with the TNF receptor-associated factor 6 and TGFß-activated kinase 1 (TRAF6-TAK1) complex, thereby initiating the activation of the downstream mitogen-activated protein kinase/nuclear factor-κB (MAPK/NF-κB) signaling cascade and subsequent gene transcription. This study expands the insight into HDAC7's role within intricate inflammatory networks and highlights its therapeutic potential as a novel target for anti-inflammatory treatments.

A practical "preTACs-cytoblot" platform accelerates the streamlined development of PROTAC-based protein degraders.

With the growing importance of PROTAC-mediated protein degradation in drug discovery, robust synthetic methodologies and rapid screening assays are urgently needed. By harnessing the improved alkene hydroazidation reaction, we developed a novel strategy to introduce azido groups into the linker-E3 ligand conjugates and effectively created a range of prepacked terminal azide-labeled "preTACs" as PROTAC toolkit building blocks. Moreover, we demonstrated that preTACs are ready to conjugate to ligands targeting a protein of interest to generate libraries of chimeric degraders, which are subsequently screened for effective protein degradation directly from cultured cells with a cytoblot assay. Our study exemplifies that this practical "preTACs-cytoblot" platform allows efficient PROTAC assembly and rapid activity assessments. It may help industrial and academic investigators to accelerate their streamlined development of PROTAC-based protein degraders.

Senotherapies: A novel strategy for synergistic anti-tumor therapy.

Cellular senescence was initially considered an effective antitumor mechanism, and senescence-induced therapy has previously been regarded as an efficient treatment. However, increasing studies have discovered that persistent senescent cells (SNCs) might have unanticipated negative repercussions for antitumor treatment. The long-term build-up of SNCs exacerbates toxic side effects, treatment resistance, and poor prognosis, and tumor cells that undergo senescence escape can acquire stemness to repopulate the tumor, leading to cancer recurrence. Thus, senotherapies that eliminate SNCs could be used as a new strategy for synergistic antitumor therapy. In this review, we summarize the adverse effects of SNCs in tumor development and the mechanisms by which senescent tumor cells escape senescence, discuss the relationship between senescence and polyploidy, and highlight the potential of senotherapies as an emerging adjuvant antitumor treatment strategy. Such a strategy is expected to provide new approaches for antitumor drug development from the perspective of cellular senescence.

Identification and Validation of Two Heterogeneous Molecular Subtypes and a Prognosis Predictive Model for Hepatocellular Carcinoma Based on Pyroptosis.

Hepatocellular carcinoma (HCC) is a worldwide malignant cancer with high incidence and mortality. Considering the high heterogeneity of HCC, clarifying molecular characteristics associated with HCC development could help improve patients' outcomes. Pyroptosis is a novel form of cell death and is noted to be implicated in HCC pathogenesis whereas its molecular feature in HCC is unclear. Thus, we intended to clarify the molecular characteristic as well as the clinical significance of pyroptosis for HCC. A systematic bioinformatics analysis was conducted among 40 pyroptosis-related genes based on The Cancer Genome Atlas, the International Cancer Genome Consortium, and the Gene Expression Omnibus databases. A total of 12 HCC-associated pyroptosis-related genes (HPRGs) were identified to be overexpressed in HCC tissues and significantly connected to patients' poor survival. Through consensus clustering based on the HPRGs' expression, we found patients could be stratified into two distinctive pyroptosis subtypes, PyLow and PyHigh. The PyHigh group owned a notable lower survival rate and a higher high-grade proportion compared with the PyLow subtype. Besides, patients' sensitivities to chemotherapeutic drugs also presented distinctive differences between the two subtypes. Indicated by pathway enrichment analysis and immune characteristic difference analysis, the distinctions between the pyroptosis subtypes may be related to tumor immunity. Further, a five-gene risk model composed of BAK1, CHMP4A, CHMP4B, DHX9, and GSDME was established. Subsequent analyses demonstrated that the model could credibly classify patients as low or high risk and was an independent prognostic indicator for HCC. Abnormal expressions of the five genes were validated by biological experiments and new bioinformatics analysis. In conclusion, this study recognized and verified two heterogeneous pyroptosis subtypes and a predictable prognosis model for HCC. Our work may help facilitate the clinical management and treatment of HCC and understand the functions of pyroptosis in oncology.