DAZAP1 Phase Separation Regulates Mitochondrial Metabolism to Facilitate Invasion and Metastasis of Oral Squamous Cell Carcinoma.

Tumor invasion and metastasis are the underlying causes of the high mortality rate of oral squamous cell carcinoma (OSCC). Energy metabolism reprogramming has been identified as a crucial process mediating tumor metastasis, thus indicating an urgent need for in-depth investigation of the specific mechanisms of tumor energy metabolism. Here, we identified an RNA-binding protein, DAZ associated protein 1 (DAZAP1), as a tumor-promoting factor with an important role in OSCC progression. DAZAP1 was significantly upregulated in OSCC, which enhanced the migration and invasion of OSCC cells and induced the epithelial-mesenchymal transition (EMT). RNA-seq analysis and experimental validation demonstrated that DAZAP1 regulates mitochondrial energy metabolism in OSCC. Mechanistically, DAZAP1 underwent liquid-liquid phase separation (LLPS) to accumulate in the nucleus where it enhanced cytochrome-c oxidase 16 (COX16) expression by regulating pre-mRNA alternative splicing, thereby promoting OSCC invasion and mitochondrial respiration. In mouse OSCC models, loss of DAZAP1 suppressed EMT, downregulated COX16, and reduced tumor growth and metastasis. In OSCC patient samples, expression of DAZAP1 positively correlated with COX16, and high expression of both proteins was associated with poor patient prognosis. Together, these findings revealed a mechanism by which DAZAP1 supports mitochondrial metabolism and tumor development of OSCC, suggesting the potential of therapeutic strategies targeting DAZAP1 to block OSCC invasion and metastasis.

Neutrophil extracellular traps promote invasion and metastasis via NLRP3-mediated oral squamous cell carcinoma pyroptosis inhibition.

Neutrophil extracellular traps (NETs) are reticular structures composed of neutrophil elastase (NE), cathepsin G (CG) and DNA-histone enzyme complexes. Accumulating evidence has revealed that NETs play important roles in tumor progression, metastasis, and thrombosis. However, our understanding of its clinical value and mechanism of action in oral squamous cell carcinoma (OSCC) is limited and has not yet been systematically described. Here, we aimed to investigate the clinical significance of NETs in OSCC and the mechanisms by which they affect its invasive and metastatic capacity. Our results demonstrated that high enrichment of NETs is associated with poor prognosis in OSCC, and mechanistic studies have shown that NE in NETs promotes invasion and metastasis via NLRP3-mediated inhibition of pyroptosis in OSCC. These findings may provide a new therapeutic approach for OSCC.

Identification of immunogenic cell death-related damage-related molecular patterns (DAMPs) to predict outcomes in patients with head and neck squamous cell carcinoma.

PURPOSE: Head and neck cancer is the sixth most common type of cancer worldwide, wherein the immune responses are closely associated with disease occurrence, development, and prognosis. Investigation of the role of immunogenic cell death-related genes (ICDGs) in adaptive immune response activation may provide cues into the mechanism underlying the outcome of HNSCC immunotherapy. METHODS: ICDGs expression patterns in HNSCC were analyzed, after which consensus clustering in HNSCC cohort conducted. A 4-gene prognostic model was constructed through LASSO and Cox regression analyses to analyze the prognostic index using the TCGA dataset, followed by validation with two GEO datasets. The distribution of immune cells and the response to immunotherapy were compared between different risk subtypes through multiple algorithms. Moreover, immunohistochemical (IHC) analyses were conducted to validate the prognostic value of HSP90AA1 as a predictor of HNSCC patient prognosis. In vitro assays were performed to further detect the effect of HSP90AA1 in the development of HNSCC. RESULTS: A novel prognostic index based on four ICDGs was constructed and proved to be useful as an independent factor of HNSCC prognosis. The risk score derived from this model grouped patients into high- and low-risk subtypes, wherein the high-risk subtype had worse survival outcomes and poorer immunotherapy response. IHC analysis validated the applicability of HSP90AA1 as a predictor of prognosis of HNSCC patients. HSP90AA1 expression in tumor cells promotes the progression of HNSCC. CONCLUSIONS: Together, these results highlight a novel four-gene prognostic signature as a valuable tool to assess survival status and prognosis of HNSCC patients.

Reactive Oxygen Species-Activated Metal-Free Carbon Monoxide Prodrugs for Targeted Cancer Treatment.

Carbon monoxide has shown promise as a therapeutic agent against cancers. Reactive oxygen species (ROS)-activated CO prodrugs are highly demanded for targeted cancer treatment but remain sporadic. In addition, little attention is on how the release rate affects CO's biological effects. Herein, we describe a new type of ROS-activated metal-free CO prodrug, which releases CO with tunable release rates in response to multiple ROS and exhibits very pronounced tumor suppression effects in a mouse 4t1 breast tumor model. Importantly, for the first time, we observe both in vitro and in vivo that CO release rate has a direct impact on its antiproliferative potency and a correlation between release rate and antiproliferative activity is observed. In aggregates, our results not only deliver ROS-sensitive CO prodrugs for cancer treatment but also represent a promising starting point for further in-depth studies of how CO release kinetics affect anticancer activity.

Chemiexcitation-Triggered Prodrug Activation for Targeted Carbon Monoxide Delivery.

Photolysis-based prodrug strategy can address some critical drug delivery issues, which otherwise are very challenging to tackle with traditional prodrug strategy. However, the need for external light irradiation significantly hampers its in vivo application due to the poor light accessibility of deep tissue. Herein, we propose a new strategy of chemiexcitation-triggered prodrug activation, wherein a photoresponsive prodrug is excited for drug payload release by chemiexcitation instead of photoirradiation. As such, the bond-cleavage power of photolysis can be employed to address some critical drug delivery issues while obviating the need for external light irradiation. We have established the proof of concept by the successful development of a chemiexcitation responsive carbon monoxide delivery platform, which exhibited specific CO release at the tumor site and pronounced tumor suppression effects. We anticipate that such a concept of chemiexcitation-triggered prodrug activation can be leveraged for the targeted delivery of other small molecule-based drug payloads.

Preparation of a Self-Assembled Rhein-Doxorubicin Nanogel Targeting Mitochondria and Investigation on Its Antihepatoma Activity.

Mitochondria are involved in the regulation of apoptosis, making them a promising target for the development of new anticancer drugs. Doxorubicin (DOX), a chemotherapeutic drug, can induce reactive oxygen species (ROS)-mediated apoptosis, improving its anticancer effects. Herein, Rhein, an active ingredient in rhubarb, with the capability of self-assembly and mitochondrial targeting, was used in conjunction with DOX to form efficient nanomaterials (Rhein-DOX nanogel) capable of sustained drug release. It was self-assembled with a hydrogen bond, π-π stacking interactions, and hydrophobic interactions as the main driving force, and its loading efficiency was up to 100%. Based on its self-assembly characteristics, we evaluated the mechanism of this material to target mitochondria, induce ROS production, and promote apoptosis. The IC50 of the Rhein-DOX nanogel (3.74 µM) was only 46.3% of that of DOX (11.89 µM), and the tumor inhibition rate of the Rhein-DOX nanogel was 79.4% in vivo, 2.3 times that of DOX. This study not only addresses the disadvantages of high toxicity of DOX and low bioavailability of Rhein, when DOX and Rhein are combined for the treatment of hepatoma, but it also significantly improved the synergistic antihepatoma efficacy of Rhein and DOX, which provides a new idea for the development of long-term antihepatoma agents with low toxicity.

Simultaneous determination of nineteen compounds of Dahuang zhechong pill in rat plasma by UHPLC-MS/MS and its application in a pharmacokinetic study.

Dahuang zhechong pill (DHZCP) is a famous traditional Chinese medicine prescription, which is widely used in the treatment of liver diseases. However, due to the lack of a dynamic DHZCP profile, the in vivo pharmacokinetics of active ingredients within this medicine remains unknown. In this paper, a rapid, sensitive and reliable UHPLC-MS/MS method was used to determine the content of 19 characteristic constituents of DHZCP in rat plasma, including rhein, emodin, chrysophanol, physcion, aloeemodin, p-methoxyphenylacetic acid, hypoxanthine nucleoside, wogonin, wogonoside, baicalin, norwogonin, naringenin, nutmeg acid, paeoniflorin, verbascoside, rhodiola glucoside, forsythoside A, formononetin, and glycyrrhizic acid. An Agilent Extend-C18 column (2.1 mm × 100 mm, 1.8 µm) was used to separate the 19 characteristic constituents, with a mobile phrase of (A) 0.1% formic acid and (B) acetonitrile. The constituents were detected in negative ion mode with multiple reactions monitoring (MRM). The established UHPLC-MS/MS method had good linearity, with a coefficient of determination (r2) of >0.99. The daytime and intra-day precision were less than 12%, and the accuracy ranged from -9.56% to 7.82%. The stability, extraction recovery, and matrix effect met the requirements. The method was successfully applied to the pharmacokinetic study of these nineteen characteristic constituents after oral administration of DHZCP. UHPLC-MS/MS was used for the first time to study the pharmacokinetics of the characteristic chemical constituents in DHZCP, which provided reference and theoretical guidance for further clarification of its pharmacodynamic basis.

Rhein reverses doxorubicin resistance in SMMC-7721 liver cancer cells by inhibiting energy metabolism and inducing mitochondrial permeability transition pore opening.

Rhein, a monomeric anthraquinone obtained from the plant herb species Polygonum multiflorum and P. cuspidatum, has been proposed to have anticancer activity. This activity has been suggested to be associated with mitochondrial injury due to the induction of mitochondrial permeability transition pore (mPTP) opening. In this study, the effects of 5-80 µM rhein on cell viability, half-maximal inhibitory concentration (IC50 value), resistance index, and apoptosis were assessed in the liver cancer cell lines SMMC-7721 and SMMC-7721/DOX (doxorubicin-resistant cells). Rhein (10-80 µM) significantly reduced the viability of both cell lines; 20 µM rhein significantly increased sensitivity to DOX and increased apoptosis in SMMC-7721 cells, but reversed resistance to DOX by 7.24-fold in SMMC-7721/DOX cells. Treatment with rhein increased accumulation of DOX in SMMC-7721/DOX cells, inhibited mitochondrial energy metabolism, decreased cellular ATP, and ADP levels, and altered the ratio of ATP to ADP. These effects may result from the binding of rhein with voltage-dependent ion channels (VDACs), adenine nucleotide translocase (ANT), and cyclophilin D, affecting their function and leading to the inhibition of ATP transport by VDACs and ANT. ATP synthesis was greatly reduced and mitochondrial inner membrane potential decreased. Together, these results indicate that rhein could reverse drug resistance in SMMC-7721/DOX cells by inhibiting energy metabolism and inducing mPTP opening. © 2018 BioFactors, 45(1):85-96, 2019.