Use of the γ-H2AX assay to monitor DNA damage and repair in translational cancer research

Influence of alkylthio and arylthio derivatives of tert-butylquinone on the induction of DNA damage in a human hepatocellular carcinoma cell line (HepG2)

The aim of this study was to investigate the effects of tert-butylquinone (TBQ) and its alkylthio and arylthio derivatives on DNA in vitro, using acellular and cellular test systems. Direct interaction with DNA was studied using the plasmid pUC19. Cytotoxic (MTS assay) and genotoxic (comet assay and γH2AX focus assays) effects, and their influence on the cell cycle were studied in the HepG2 cell line. Our results show that TBQ and its derivatives did not directly interact with DNA. The strongest cytotoxic effect on the HepG2 cells was observed for the derivative 2-tert-butyl-5,6-(ethylenedithio)-1,4-benzoquinone (IC50 64.68 and 55.64 μM at 24-h and 48-h treatment, respectively). The tested derivatives did not significantly influence the cell cycle distribution in the exposed cellular populations. However, all derivatives showed a genotoxic activity stronger than that of TBQ in the comet assay, with 2-tert-butyl-5,6-(ethylenedithio)-1,4-benzoquinone producing the strongest effect. The same derivative also induced DNA double-strand breaks in the γH2AX focus assay.

Design and synthesis of nucleic acid nano-environment interactome-targeting small molecule PROTACs and their anticancer activity

Targeted protein degradation through PROteolysis TArgeting Chimeras (PROTACs) is a relatively new modality in cellular interventions. The minimum requirement for PROTACs to function is forming a tertiary complex of the protein of interest (POI), E3 ligase, and the molecular glue PROTAC. Here, we propose a new approach to modulate the nano-environment interactome of a non-protein target through a plausible quaternary complex of interactome-biomolecule of interest (BOI)-PROTAC and E3 ligase. We report nucleic acid-targeting PROTAC (NA-TAC) molecules by conjugating DNA-binding and E3 ligase ligands. We demonstrate that NA-TACs can target the G-quadruplex DNA and induce elevated DNA damage and cytotoxicity compared to the conventional G-quadruplex binding ligands. Our new class of NA-TACs lays the foundation for small molecule-based non-protein targeting PROTACs for interactome and nanoenvironment mapping and nucleic acid-targeted precision medicines.

Delayed tumor-draining lymph node irradiation preserves the efficacy of combined radiotherapy and immune checkpoint blockade in models of metastatic disease

Cancer resistance to immune checkpoint inhibitors motivated investigations into leveraging the immunostimulatory properties of radiotherapy to overcome immune evasion and to improve treatment response. However, clinical benefits of radiotherapy-immunotherapy combinations have been modest. Routine concomitant tumor-draining lymph node irradiation (DLN IR) might be the culprit. As crucial sites for generating anti-tumor immunity, DLNs are indispensable for the in situ vaccination effect of radiotherapy. Simultaneously, DLN sparing is often not feasible due to metastatic spread. Using murine models of metastatic disease in female mice, here we demonstrate that delayed (adjuvant), but not neoadjuvant, DLN IR overcomes the detrimental effect of concomitant DLN IR on the efficacy of radio-immunotherapy. Moreover, we identify IR-induced disruption of the CCR7-CCL19/CCL21 homing axis as a key mechanism for the detrimental effect of DLN IR. Our study proposes delayed DLN IR as a strategy to maximize the efficacy of radio-immunotherapy across different tumor types and disease stages.

Quantitative evaluation of trastuzumab deruxtecan pharmacokinetics and pharmacodynamics in mouse models of varying degrees of HER2 expression

Trastuzumab deruxtecan (T-DXd; DS-8201; ENHERTU®) is a human epithelial growth factor receptor 2 (HER2)-directed antibody drug conjugate (ADC) with demonstrated antitumor activity against a range of tumor types. Aiming to understand the relationship between antigen expression and downstream efficacy outcomes, T-DXd was administered in tumor-bearing mice carrying NCI-N87, Capan-1, JIMT-1, and MDA-MB-468 xenografts, characterized by varying HER2 levels. Plasma pharmacokinetics (PK) of total antibody, T-DXd, and released DXd and tumor concentrations of released DXd were evaluated, in addition to monitoring γΗ2AX and pRAD50 pharmacodynamic (PD) response. A positive relationship was observed between released DXd concentrations in tumor and HER2 expression, with NCI-N87 xenografts characterized by the highest exposures compared to the remaining cell lines. γΗ2AX and pRAD50 demonstrated a sustained increase over several days occurring with a time delay relative to tumoral-released DXd concentrations. In vitro investigations of cell-based DXd disposition facilitated the characterization of DXd kinetics across tumor cells. These outputs were incorporated into a mechanistic mathematical model, utilized to describe PK/PD trends. The model captured plasma PK across dosing arms as well as tumor PK in NCI-N87, Capan-1, and MDA-MB-468 models; tumor concentrations in JIMT-1 xenografts required additional parameter adjustments reflective of complex receptor dynamics. γΗ2AX longitudinal trends were well characterized via a unified PD model implemented across xenografts demonstrating the robustness of measured PD trends. This work supports the application of a mechanistic model as a quantitative tool, reliably projecting tumor payload concentrations upon T-DXd administration, as the first step towards preclinical-to-clinical translation.

Platinum (IV) drugs with cannabidiol inducing mitochondrial dysfunction and synergistically enhancing anti-tumor effects

Chemotherapy resistance is an insurmountable problem in clinical anticancer therapy. Although Oxaliplatin is an effective chemotherapeutic agent for the treatment of colorectal cancer (CRC), it still suffers from serious toxicities as well as drug resistance. In this work, three Oxaliplatin tetravalent platinum prodrugs(O1-O3) and three novel mixed ammine/amine analogs(C1-C3) were constructed, introducing cannabidiol with anti-tumor activity in their axial position. All Pt(IV) prodrugs exhibited potent antitumor effects in a variety of tumor cell lines, especially in HCT-116 cells, where complex O3 showed strong inhibitory effects with the half maximal inhibitory concentrations (IC50) value of 6.02 ± 0.69 μM and about 2.6 times higher than that of Oxaliplatin. Further studies revealed that complex O3 decreased cellular mitochondrial membrane potential in a concentration-dependent manner and enhanced reactive oxygen species (ROS) accumulation by decreasing the expression of catalase, superoxide dismutase 2 (SOD2) and superoxide dismutase 3 (SOD3). Complex O3 induces mitochondrial dysfunction and upregulates the pro-apoptotic protein Noxa, ultimately leading to severe DNA damage. The upregulation of Phosphorylated histone protein H2AX (γ-H2AX) expression is clear evidence. In addition, O3 inhibits the expression of RAD51 protein and prevents DNA damage repair, thus overcoming drug resistance. This strategy of combining bioactive molecules cannabidiol with platinum drugs to improve therapeutic efficacy and overcome drug resistance has been proven to be very effective and deserves further investigation.

Lovastatin/SN38 co-loaded liposomes amplified ICB therapeutic effect via remodeling the immunologically-cold colon tumor and synergized stimulation of cGAS-STING pathway

Current immune checkpoint blockade (ICB) immunotherapeutics have revolutionized cancer treatment. However, many cancers especially the "immunologically cold" tumors, do not respond to ICB, prompting the search for additional strategies to achieve durable responses. The cGAS-STING pathway, as an essential immune response pathway, has been demonstrated for a potent target to sensitize ICB immunotherapy. However, the low efficiency of conventional STING agonists limits their clinical application. Recent studies have shown that DNA topoisomerase I (TOPI) inhibitor chemodrug SN38 can activate the cGAS-STING pathway and induce an immune response through DNA damage, while the traditional statins medication lovastatin was found to inhibit DNA damage repair, which may in turn upregulate the damaged DNA level. Herein, we have developed a liposomal carrier co-loaded with SN38 and lovastatin (SL@Lip), which can be accumulated in tumors and efficiently released SN38 and lovastatin, addressing the problem of weak solubility of these two drugs. Importantly, lovastatin can increase DNA damage and enhance the activation of cGAS-STING pathway, coordinating with SN38 chemotherapy and exhibiting the enhanced combinational immunotherapy of PD-1 antibody by remodeling the tumor microenvironment in mouse colorectal cancer of both subcutaneous and orthotopic xenograft models. Overall, this study demonstrates that lovastatin-assisted cGAS-STING stimulation mediated by liposomal delivery system significantly strengthened both chemotherapy and immunotherapy of colorectal cancer, providing a clinically translational strategy for combinational ICB therapy in the "immunologically cold" tumors.

Design, synthesis and biological evaluation of matrine contains benzimidazole derivatives as dual TOPOI and PARP inhibitors for cancer therapy

TOPOI inhibitors have long been a focal point in the research and development of antitumor drugs. PARP-1 plays a crucial role in repairing DNA damage induced by TOPOI inhibitors. Thus, concurrent inhibition of TOPOI and PARP-1 has the potential to augment drug activity. Matrine, characterized by low toxicity and good water solubility, offers advantageous properties. In this investigation, a series of benzimidazole matrine derivatives were designed and synthesized using matrine as the lead compound with the aim of developing dual inhibitors targeting both TOPOI and PARP-1. Among these derivatives, Compound B6 exhibited potent inhibitory effects on PARP-1 and TOPOI, effectively suppressing cancer cell proliferation and migration. Mechanistic assessments revealed that B6 induced DNA damage in HGC-27 cells, leading to G0/G1 cell cycle arrest and significant apoptosis. Molecular docking experiments demonstrated that B6 can effectively enter the active pocket of target proteins, where it forms stable hydrogen bonds with amino acid residues. In vivo, experiments demonstrated that B6 exhibited antitumor activity comparable to that of the positive control drug. The tumor growth inhibition rates (TGIs) for irinotecan, B6 and matrine were 87.0%, 75.4% and 9.7%, respectively. Importantly, B6 demonstrated lower toxicity than the positive control drug. Our findings suggest that TOPOI and PARP-1 may represent potential targets for matrine and B6 emerges as a promising candidate for cancer therapy.

Polyphenolic Platform Ameliorated Sanshool for Skin Photoprotection

Natural evolution has nurtured a series of active molecules that play vital roles in physiological systems, but their further applications have been severely limited by rapid deactivation, short cycle time, and potential toxicity after isolation. For instance, the instability of structures and properties has greatly descended when sanshool is derived from Zanthoxylum xanthoxylum. Herein, natural polyphenols are employed to boost the key properties of sanshool by fabricating a series of nanoparticles (NPs). The intracellular evaluation and in vivo animal model are conducted to demonstrate the decreased photodamage score and skin-fold thickness of prepared NPs, which can be attributed to the better biocompatibility, improved free radical scavenging, down-regulated apoptosis ratios, and reduced DNA double-strand breaks compared to naked sanshool. This work proposes a novel strategy to boost the key properties of naturally occurring active molecules with the assistance of natural polyphenol-based platforms.

Radiation responsive PROTAC nanoparticles for tumor-specific proteolysis enhanced radiotherapy

Proteolysis targeting chimeras (PROTACs) is a promising strategy for cancer therapy. However, the always-on bioactivity of PROTACs may lead to non-target toxicity, which restricts their antitumor performance. Here, we developed an X-ray radiation responsive PROTAC nanomicelle (RCNprotac) by covalently conjugating a reported small molecule PROTAC (MZ1) to hydrophilic PEG via a diselenide bond-containing carbon chain, which then self-assembled into a 141.80 ± 5.66 nm nanomicelle. The RCNprotac displayed no bioactivity during circulation due to the occupation of the hydroxyl group on the E3 ubiquitin ligand component and could effectively accumulate at the tumor site owing to the enhanced permeability and retention effect. Upon exposure to X-ray radiation, the radiation-sensitive diselenide bonds were broken to specifically release MZ1 for tumor BRD4 protein degradation. Furthermore, the reduction in the BRD4 protein level could increase the tumor's sensitivity to radiation. RCNprotac showed a synergistic enhancement of antitumor effects both in vitro and in vivo. We believe that this X-ray-responsive PROTAC nanomicelle could provide a new strategy for the X-ray-activated spatiotemporally controlled protein degradation and for the BRD4 proteolysis enhanced tumor radiosensitivity.

Roles of Histone H2A Variants in Cancer Development, Prognosis, and Treatment

Histones are nuclear proteins essential for packaging genomic DNA and epigenetic gene regulation. Paralogs that can substitute core histones (H2A, H2B, H3, and H4), named histone variants, are constitutively expressed in a replication-independent manner throughout the cell cycle. With specific chaperones, they can be incorporated to chromatin to modify nucleosome stability by modulating interactions with nucleosomal DNA. This allows the regulation of essential fundamental cellular processes for instance, DNA damage repair, chromosomal segregation, and transcriptional regulation. Among all the histone families, histone H2A family has the largest number of histone variants reported to date. Each H2A variant has multiple functions apart from their primary role and some, even be further specialized to perform additional tasks in distinct lineages, such as testis specific shortH2A (sH2A). In the past decades, the discoveries of genetic alterations and mutations in genes encoding H2A variants in cancer had revealed variants' potentiality in driving carcinogenesis. In addition, there is growing evidence that H2A variants may act as novel prognostic indicators or biomarkers for both early cancer detection and therapeutic treatments. Nevertheless, no studies have ever concluded all identified variants in a single report. Here, in this review, we summarize the respective functions for all the 19 mammalian H2A variants and their roles in cancer biology whilst potentiality being used in clinical setting.

DNA topoisomerase II inhibition potentiates osimertinib's therapeutic efficacy in EGFR-mutant non-small cell lung cancer models

Development of effective strategies to manage the inevitable acquired resistance to osimertinib, a third-generation EGFR inhibitor for the treatment of EGFR-mutant (EGFRm) non-small cell lung cancer (NSCLC), is urgently needed. This study reports that DNA topoisomerase II (Topo II) inhibitors, doxorubicin and etoposide, synergistically decreased cell survival, with enhanced induction of DNA damage and apoptosis in osimertinib-resistant cells; suppressed the growth of osimertinib-resistant tumors; and delayed the emergence of osimertinib-acquired resistance. Mechanistically, osimertinib decreased Topo IIα levels in EGFRm NSCLC cells by facilitating FBXW7-mediated proteasomal degradation, resulting in induction of DNA damage; these effects were lost in osimertinib-resistant cell lines that possess elevated levels of Topo IIα. Increased Topo IIα levels were also detected in the majority of tissue samples from patients with NSCLC after relapse from EGFR tyrosine kinase inhibitor treatment. Enforced expression of an ectopic TOP2A gene in sensitive EGFRm NSCLC cells conferred resistance to osimertinib, whereas knockdown of TOP2A in osimertinib-resistant cell lines restored their susceptibility to osimertinib-induced DNA damage and apoptosis. Together, these results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of osimertinib against EGFRm NSCLC, providing scientific rationale for targeting Topo II to manage acquired resistance to osimertinib.

Vitamin C Inhibited Pulmonary Metastasis through Activating Nrf2/HO-1 Pathway

As an important nutritional component, vitamin C (Vc) shows good antitumor activity in a variety of cancer, but there are few studies in pulmonary metastasis. In order to verify its anticancer and antimetastatic effect, the study sets up H22 pulmonary metastasis mouse model. The results show that intraperitoneal injection of Vc inhibits pulmonary metastasis through up-regulating the expression of Nrf2, HO-1, cleaved caspases 3 and 9, and causing DNA damage and apoptosis which is similar to the pro-oxidant effect of Vc in p53 null cells (H1299 cells). Meanwhile, oral administration of Vc up-regulates the expression of p53, directly activates Nrf2/HO-1 pathway, increases expression of cleaved caspases 3 and 9, and ultimately inhibits pulmonary metastasis, which is the same as the antioxidant result of Vc in p53 wild-type cells. In addition, Vc inhibits the proliferation and migration of lung cancer cells in a concentration-dependent manner and has little cytotoxic effects on normal cells. Notably, the experiment further illustrates that besides intravenous Vc, oral Vc significantly inhibits the pulmonary metastasis in mice. All in all, these findings provide new clues for Vc-treated pulmonary metastasis in clinical research.

Tumor targeted alpha particle therapy with an actinium-225 labelled antibody for carbonic anhydrase IX

Selective antibody targeted delivery of α particle emitting actinium-225 to tumors has significant therapeutic potential. This work highlights the design and synthesis of a new bifunctional macrocyclic diazacrown ether chelator, H2MacropaSqOEt, that can be conjugated to antibodies and forms stable complexes with actinium-225. The macrocyclic diazacrown ether chelator incorporates a linker comprised of a short polyethylene glycol fragment and a squaramide ester that allows selective reaction with lysine residues on antibodies to form stable vinylogous amide linkages. This new H2MacropaSqOEt chelator was used to modify a monoclonal antibody, girentuximab (hG250), that binds to carbonic anhydrase IX, an enzyme that is overexpressed on the surface of cancers such as clear cell renal cell carcinoma. This new antibody conjugate (H2MacropaSq-hG250) had an average chelator to antibody ratio of 4 : 1 and retained high affinity for carbonic anhydrase IX. H2MacropaSq-hG250 was radiolabeled quantitatively with [225Ac]AcIII within one minute at room temperature with micromolar concentrations of antibody and the radioactive complex is stable in human serum for >7 days. Evaluation of [225Ac]Ac(MacropaSq-hG250) in a mouse xenograft model, that overexpresses carbonic anhydrase IX, demonstrated a highly significant therapeutic response. It is likely that H2MacropaSqOEt could be used to modify other antibodies providing a readily adaptable platform for other actinium-225 based therapeutics.

Targeting KDM4 family epigenetically triggers antitumour immunity via enhancing tumour-intrinsic innate sensing and immunogenicity

Despite the remarkable clinical efficacy of cancer immunotherapy, considerable patients fail to benefit from it due to primary or acquired resistance. Tumours frequently hijack diverse epigenetic mechanisms to evade immune detection, thereby highlighting the potential for pharmacologically targeting epigenetic regulators to restore the impaired immunosurveillance and re-sensitise tumours to immunotherapy. Herein, we demonstrated that KDM4-targeting chemotherapeutic drug JIB-04, epigenetically triggered the tumour-intrinsic innate immune responses and immunogenic cell death (ICD), resulting in impressive antitumour effects. Specifically, JIB-04 induced H3K9 hypermethylation through specific inhibition of the KDM4 family (KDM4A-D), leading to impaired DNA repair signalling and subsequent DNA damage. As a result, JIB-04 not only activated the tumour-intrinsic cyclic GMP-AMP synthase (cGAS)-STING pathway via DNA-damage-induced cytosolic DNA accumulation, but also promoted ICD, releasing numerous damage-associated molecular patterns. Furthermore, JIB-04 induced adaptive resistance through the upregulation of programmed death-ligand 1 (PD-L1), which could be overcome with additional PD-L1 blockade. In human tumours, KDM4B expression was negatively correlated with clinical outcomes, type I interferon signatures, and responses to immunotherapy. In conclusion, our results demonstrate that targeting KDM4 family can activate tumour-intrinsic innate sensing and immunogenicity, and synergise with immunotherapy to improve antitumour outcomes.

Plant histone variants at the nexus of chromatin readouts, stress and development

Histones are crucial proteins that are involved in packaging the DNA as condensed chromatin inside the eukaryotic cell nucleus. Rather than being static packaging units, these molecules undergo drastic variations spatially and temporally to facilitate accessibility of DNA to replication, transcription as well as wide range of gene regulatory machineries. In addition, incorporation of paralogous variants of canonical histones in the chromatin is ascribed to specific functions. Given the peculiar requirement of plants to rapidly modulate gene expression levels on account of their sessile nature, histones and their variants serve as additional layers of gene regulation. This review summarizes the mechanisms and implications of distribution, modifications and differential incorporation of histones and their variants across plant genomes, and outlines emerging themes.

A novel benzothiazole-based mononuclear platinum(II) complex displaying potent antiproliferative activity in HepG-2 cells via mitochondrial-mediated apoptosis

A novel mononuclear platinum(II) complex, [Pt(L-H)Cl] (1, where L= N-(4-(benzo[d]thiazol-2-yl)phenyl)-2-((2-pyridylmethyl)(2-hydroxyethyl)-amino)acetamide), was obtained by covalently tethering a benzothiazole derivative 2-(4-aminophenyl)benzothiazole to the 2-pyridylmethyl-2-hydroxyethylamine chelating PtII center. In vitro tests indicated that complex 1 displayed excellent antiproliferative activity against the tested cancer cell lines, especially liver cancer HepG-2 and SMMC-7221 cells. Importantly, the complex possessed 4.33-fold higher antiproliferative activity as compared with cisplatin against HepG-2 cells, but was less toxic to the normal cell line L02 with the selectivity index (SI = IC50(L02)/IC50(HepG-2)) value of 8.36 compared to cisplatin (SI, 1.40). The results suggested that 1 might have the potential to act as a candidate for the treatment of hepatocellular carcinoma (HCC). Cellular uptake and distribution studies showed that 1 could effectively pass through the membrane of cells, enter the nuclei and mitochondria, induce the platination of cellular DNA. The interaction of 1 with CT-DNA demonstrated that 1 could effectively bind to DNA in a dual binding mode, i.e., the intercalation of the 2-(4-aminophenyl)benzothiazole unit plus monofunctional platination of the platinum(II) moiety. In addition, Hoechst 33342 staining and flow cytometry analysis illustrated that 1 arrested the cell cycle in HepG-2 cancer cells at G2/M phases, induced mitochondrial membrane depolarization, increased ROS generation, and caused obvious cell apoptosis. Further cellular mechanism studies elucidated that 1 triggered HepG-2 cell apoptosis via the mitochondrial-mediated pathway by upregulating the gene and protein expression levels of Bax, downregulating the gene and protein expression levels of Bcl-2, and activating the caspase cascade.

Intratumoral Biosynthesis of Gold Nanoclusters by Pancreatic Cancer to Overcome Delivery Barriers to Radiosensitization

Nanoparticle delivery to solid tumors is a prime challenge in nanomedicine. Here, we approach this challenge through the lens of biogeochemistry, the field that studies the flow of chemical elements within ecosystems as manipulated by living cellular organisms and their environments. We leverage biogeochemistry concepts related to gold cycling against pancreatic cancer, considering mammalian organisms as drivers for gold nanoparticle biosynthesis. Sequestration of gold nanoparticles within tumors has been demonstrated as an effective strategy to enhance radiotherapy; however, the desmoplasia of pancreatic cancer impedes nanoparticle delivery. Our strategy overcomes this barrier by applying an atomic-scale agent, ionic gold, for intratumoral gold nanoparticle biosynthesis. Our comprehensive studies showed the cancer-specific synthesis of gold nanoparticles from externally delivered gold ions in vitro and in a murine pancreatic cancer model in vivo; a substantial colocalization of gold nanoparticles (GNPs) with cancer cell nuclei in vitro and in vivo; a strong radiosensitization effect by the intracellularly synthesized GNPs; a uniform distribution of in situ synthesized GNPs throughout the tumor volume; a nearly 40-day total suppression of tumor growth in animal models of pancreatic cancer treated with a combination of gold ions and radiation that was also associated with a significantly higher median survival versus radiation alone (235 vs 102 days, respectively).

Exploring RAD18-dependent replication of damaged DNA and discontinuities: A collection of advanced tools

DNA damage tolerance (DDT) pathways mitigate the effects of DNA damage during replication by rescuing the replication fork stalled at a DNA lesion or other barriers and also repair discontinuities left in the newly replicated DNA. From yeast to mammalian cells, RAD18-regulated translesion synthesis (TLS) and template switching (TS) represent the dominant pathways of DDT. Monoubiquitylation of the polymerase sliding clamp PCNA by HRAD6A-B/RAD18, an E2/E3 protein pair, enables the recruitment of specialized TLS polymerases that can insert nucleotides opposite damaged template bases. Alternatively, the subsequent polyubiquitylation of monoubiquitin-PCNA by Ubc13-Mms2 (E2) and HLTF or SHPRH (E3) can lead to the switching of the synthesis from the damaged template to the undamaged newly synthesized sister strand to facilitate synthesis past the lesion. When immediate TLS or TS cannot occur, gaps may remain in the newly synthesized strand, partly due to the repriming activity of the PRIMPOL primase, which can be filled during the later phases of the cell cycle. The first part of this review will summarize the current knowledge about RAD18-dependent DDT pathways, while the second part will offer a molecular toolkit for the identification and characterization of the cellular functions of a DDT protein. In particular, we will focus on advanced techniques that can reveal single-stranded and double-stranded DNA gaps and their repair at the single-cell level as well as monitor the progression of single replication forks, such as the specific versions of the DNA fiber and comet assays. This collection of methods may serve as a powerful molecular toolkit to monitor the metabolism of gaps, detect the contribution of relevant pathways and molecular players, as well as characterize the effectiveness of potential inhibitors.

Epigenetic downregulation of O6-methylguanine-DNA methyltransferase contributes to chronic hexavalent chromium exposure-caused genotoxic effect and cell transformation

Hexavalent chromium [Cr(VI)] is a common environmental pollutant and chronic exposure to Cr(VI) causes lung cancer and other types of cancer in humans, although the mechanism of Cr(VI) carcinogenesis remains elusive. Cr(VI) has been considered as a genotoxic carcinogen, but accumulating evidence indicates that Cr(VI) also causes various epigenetic toxic effects that play important roles in Cr(VI) carcinogenesis. However, it is not clear how Cr(VI)-caused epigenetic dysregulations contributes to Cr(VI) carcinogenesis. This study investigates whether Cr(VI) epigenetic toxic effect has an impact on its genotoxic effect. It was found that chronic low dose of Cr(VI) exposure time-dependently down-regulates the expression of a critical DNA damage repair protein O6-methylguanine-DNA methyltransferase (MGMT), leading to the increases of the levels of the highly mutagenic and carcinogenic DNA lesion O6-methylguanine (O6-MeG) in human bronchial epithelial BEAS-2B cells. Moreover, the levels of MGMT and O6-MeG in chronic Cr(VI) exposure-caused human lung cancer tissues are also significantly lower and higher than that in the adjacent normal lung tissues, respectively. It was further determined that chronic low dose of Cr(VI) exposure-transformed BEAS-2B cells display impaired DNA damage repair capacity and a high sensitivity to the toxicity of the alkylating chemotherapeutic drug Temozolomide. In contrast, stably overexpressing MGMT in parental BEAS-2B cells reverses chronic low dose of Cr(VI) exposure-caused DNA damage repair deficiency and significantly reduces cell transformation by Cr(VI). Further mechanistical studies revealed that chronic low dose of Cr(VI) exposure down-regulates MGMT expression through epigenetic mechanisms by increasing DNA methylation and histone H3 repressive modifications. Taken together, these findings suggest that epigenetic down-regulation of a crucial DNA damage repair protein MGMT contributes significantly to the genotoxic effect and cell transformation caused by chronic low dose of Cr(VI) exposure.

Induction of resistance to oxaliplatin in cancer by a microRNA/Fem1B/Gli1 pathway

Colorectal cancer is among the most common cancers worldwide and a frequent cause of cancer related deaths. Oxaliplatin is the first line chemotherapeutics for treatment, but the development of resistance leads to recurrence of oxaliplatin insensitive tumors. To understand possible mechanisms of drug tolerance we developed oxaliplatin resistant derivatives (OR-LoVo) of the established LoVo cell line originally isolated from a metastatic colon adenocarcinoma. We compared the microRNA (miRNA) expression profile of the cell pair and found expression of miR-29a-3p significantly increased in OR-LoVo cells compared to parent cells. In addition, miR-29a-3p was significantly elevated in tumor tissue when compared to matched surrounding tissue in human, suggesting potential clinical importance. Ectopic miR-29-a-3p expression induced chemoresistance in a number of different cancer cell lines as well as colorectal tumors in mice. We further demonstrated that miR-29-a-3p downregulates expression of the ubiquitin ligase component FEM1B and that reduction of Fem1b levels is sufficient to confer oxaliplatin resistance. FEM1B targets the glioma associated oncogene Gli1 for degradation, suggesting that increased Gli1 levels could contribute to oxaliplatin tolerance. Accordingly, knockdown of GLI1 reverted chemoresistance of OR-LoVo cells. Mechanistically, resistant cells experienced significantly lower DNA damage upon oxaliplatin treatment, which can be partially explained by reduced oxaliplatin uptake and enhanced repair. These results suggest that miR-29-a-3p overexpression induces oxaliplatin resistance through misregulation of Fem1B and Gli1 levels. TCGA analyses provides strong evidence that the reported findings regarding induced drug tolerance by the miR-29a/Fem1B axis is clinically relevant. The reported findings can help to predict oxaliplatin sensitivity and resistance of colorectal tumors.

Indirubin derivatives as bifunctional molecules inducing DNA damage and targeting PARP for the treatment of cancer

Based on the facts that significant synergistic effect existed between PARP inhibitors and DNA damage agents and the DNA damage caused by indirubin's derivatives, we herein adopted the strategy to combine the pharmacophores of PARP inhibitors and the unique scaffold of indirubin to design a series of bifunctional molecules inducing DNA damage and targeting PARP. After SAR studies, the most potent compound 12a, encoded as KWWS-12a, exhibited improved inhibitory effect against PARP1 compared with PARP1 inhibitor Olaparib (IC50 = 1.89 nM vs 7.48 nM) and enhanced antiproliferative activities than the combination of Olaparib and indirubin-3'-monoxime towards HCT-116 cells (IC50 = 0.31 μM vs 1.37 μM). In the normal NCM-460 cells, 12a showed low toxicity (IC50 > 60 μM). The mechanism research indicated that 12a could increase the levels of γH2AX concentration dependently, arrest the cell cycle in S phase and induce apoptosis in HCT-116 cells. In vivo experiments showed that 12a displayed more significant antitumor potential than that of the positive controls. Our studies demonstrated that 12a could be a promising candidate for cancer therapy.

miR-653-3p promotes genomic instability of colorectal cancer cells via targeting SIRT1/TWIST1 signaling pathway

Development of colorectal cancer (CRC) accompanied with genomic instability. Genomic instability was promoted by microRNAs (miRNAs) inhibiting key genes in DNA damage repair and spindle assembly processes. Whether miR-653-3p affects genomic instability is unknown. The aim of this study is to explore the effect of miR-653-3p on genomic instability in CRC cells. Based on RT-qPCR analysis, miR-653-3p was highly expressed in CRC cells. Through single-cell electrophoresis assay and chromosome karyotype analysis, we determined ectopic expression of miR-653-3p induced increased DNA damage but inhibited apoptosis by promoting chromosomal instability. Mechanistically, luciferase assay identified the direct interaction of miR-653-3p with the 3' UTR of SIRT1, and western blot analysis indicated miR-653-3p inhibited SIRT1 and then promoted STAT3 phosphorylation and TWIST1 expression. The results of karyotype analysis showed that the upregulation of SIRT1 and the downregulation of TWIST1 caused by the downregulation of miR-653-3p suppressed chromosomal instability. Additionally, our evidence showed that miR-653-3p promoted CRC cell proliferation, migration, and 5-FU resistance, and miR-653-3p induced the development of CRC in the xenograft mice model. Altogether, our evidence suggests that miR-653-3p regulates SIRT1/TWIST1 signaling pathway and plays an important role in promoting genomic instability, proliferation, migration, and chemoresistance of CRC cells, which may serve as a promising therapeutic target for CRC therapy.

Comparison of the radioprotective effects of the liposomal forms of five natural radioprotectants in alleviating the adverse effects of ionising irradiation on human lymphocytes and skin cells in radiotherapy

This study aims to evaluate the radioprotective effects of liposomes encapsulating curcumin (Lip-CUR), silibinin (Lip-SIL), α-tocopherol (Lip-TOC), quercetin (Lip-QUE) and resveratrol (Lip-RES) in alleviating the adverse effects of ionising irradiation on human lymphoctyes and skin cells in radiotherapy. Liposomes encapsulating the above natural radioprotectants (Lip-NRPs) were prepared by the film hydration method combined with sonication. Their radioprotective effects for the cells against X-irradiation was evaluated using trypan-blue assay and γ-H2AX assay. All prepared Lip-NRPs had a mean diameter less than 240 nm, polydispersity index less than 0.32, and zeta potential more than -23 mV. Among them, the radioprotective effect of Lip-RES was lowest, while that of Lip-QUE was highest. Lip-SIL also exhibited a high radioprotective effect despite its low DPPH-radical scavenging activity (12.9%). The radioprotective effects of Lip-NRPs do not solely depend on the free radical scavenging activity of NRPs but also on their ability to activate cellular mechanisms.

Protective Effects of Micronutrient Supplements, Phytochemicals and Phytochemical-Rich Beverages and Foods Against DNA Damage in Humans: A Systematic Review of Randomized Controlled Trials and Prospective Studies

Accumulation of deoxyribonucleic acid (DNA) damage diminishes cellular health, increases risk of developmental and degenerative diseases, and accelerates aging. Optimizing nutrient intake can minimize accrual of DNA damage. The objectives of this review are to: 1) assemble and systematically analyze high-level evidence for the effect of supplementation with micronutrients and phytochemicals on baseline levels of DNA damage in humans, and 2) use this knowledge to identify which of these essential micronutrients or nonessential phytochemicals promote DNA integrity in vivo in humans. We conducted systematic literature searches of the PubMed database to identify interventional, prospective, cross-sectional, or in vitro studies that explored the association between nutrients and established biomarkers of DNA damage associated with developmental and degenerative disease risk. Biomarkers included lymphocyte chromosome aberrations, lymphocyte and buccal cell micronuclei, DNA methylation, lymphocyte/leukocyte DNA strand breaks, DNA oxidation, telomere length, telomerase activity, and mitochondrial DNA mutations. Only randomized, controlled interventions and uncontrolled longitudinal intervention studies conducted in humans were selected for evaluation and data extraction. These studies were ranked for the quality of their study design. In all, 96 of the 124 articles identified reported studies that achieved a quality assessment score ≥ 5 (from a maximum score of 7) and were included in the final review. Based on these studies, nutrients associated with protective effects included vitamin A and its precursor β-carotene, vitamins C, E, B1, B12, folate, minerals selenium and zinc, and phytochemicals such as curcumin (with piperine), lycopene, and proanthocyanidins. These findings highlight the importance of nutrients involved in (i) DNA metabolism and repair (folate, vitamin B12, and zinc) and (ii) prevention of oxidative stress and inflammation (vitamins A, C, E, lycopene, curcumin, proanthocyanidins, selenium, and zinc). Supplementation with certain micronutrients and their combinations may reduce DNA damage and promote cellular health by improving the maintenance of genome integrity.

Multifunctional Novel Nanoplatform for Effective Synergistic Chemo-Photodynamic Therapy of Breast Cancer by Enhancing DNA Damage and Disruptions of Its Reparation

Photodynamic therapy (PDT) is an effective noninvasive therapeutic strategy that has been widely used for anti-tumor therapy by the generation of excessive highly cytotoxic ROS. However, the poor water solubility of the photosensitizer, reactive oxygen species (ROS) depleting by high concentrations of glutathione (GSH) in the tumor microenvironment and the activation of DNA repair pathways to combat the oxidative damage, will significantly limit the therapeutic effect of PDT. Herein, we developed a photosensitizer prodrug (CSP) by conjugating the photosensitizer pyropheophorbide a (PPa) and the DNA-damaging agent Chlorambucil (Cb) with a GSH-responsive disulfide linkage and demonstrated a multifunctional co-delivery nanoplatform (CSP/Ola nanoparticles (NPs)) together with DSPE-PEG2000 and PARP inhibitor Olaparib (Ola). The CSP/Ola NPs features excellent physiological stability, efficient loading capacity, much better cellular uptake behavior and photodynamic performance. Specifically, the nanoplatform could induce elevated intracellular ROS levels upon the in situ generation of ROS during PDT, and decrease ROS consumption by reducing intracellular GSH level. Moreover, the CSP/Ola NPs could amplify DNA damage by released Cb and inhibit the activation of Poly(ADP-ribose) polymerase (PARP), promote the upregulation of γ-H2AX, thereby blocking the DNA repair pathway to sensitize tumor cells for PDT. In vitro investigations revealed that CSP/Ola NPs showed excellent phototoxicity and the IC50 values of CSP/Ola NPs against MDA-MB-231 breast cancer cells were as low as 0.05-01 μM after PDT. As a consequence, the co-delivery nanoplatform greatly promotes the tumor cell apoptosis and shows a high antitumor performance with combinational chemotherapy and PDT. Overall, this work provides a potential alternative to improve the therapeutic efficiency of triple negative breast cancer cell (TNBC) treatment by synergistically enhancing DNA damage and disrupting DNA damage repair.

Targeting Replication Stress and Chemotherapy Resistance with a Combination of Sacituzumab Govitecan and Berzosertib: A Phase I Clinical Trial

PURPOSE

Despite promising preclinical studies, toxicities have precluded combinations of chemotherapy and DNA damage response (DDR) inhibitors. We hypothesized that tumor-targeted chemotherapy delivery might enable clinical translation of such combinations.

PATIENTS AND METHODS

In a phase I trial, we combined sacituzumab govitecan, antibody-drug conjugate (ADC) that delivers topoisomerase-1 inhibitor SN-38 to tumors expressing Trop-2, with ataxia telangiectasia and Rad3-related (ATR) inhibitor berzosertib. Twelve patients were enrolled across three dose levels.

RESULTS

Treatment was well tolerated, with improved safety over conventional chemotherapy-based combinations, allowing escalation to the highest dose. No dose-limiting toxicities or clinically relevant ≥grade 4 adverse events occurred. Tumor regressions were observed in 2 patients with neuroendocrine prostate cancer, and a patient with small cell lung cancer transformed from EGFR-mutant non-small cell lung cancer.

CONCLUSIONS

ADC-based delivery of cytotoxic payloads represents a new paradigm to increase efficacy of DDR inhibitors. See related commentary by Berg and Choudhury, p. 3557.

Regulation of DNA damage and transcriptional output in the vasculature through a cytoglobin-HMGB2 axis

Identifying novel regulators of vascular smooth muscle cell function is necessary to further understand cardiovascular diseases. We previously identified cytoglobin, a hemoglobin homolog, with myogenic and cytoprotective roles in the vasculature. The specific mechanism of action of cytoglobin is unclear but does not seem to be related to oxygen transport or storage like hemoglobin. Herein, transcriptomic profiling of injured carotid arteries in cytoglobin global knockout mice revealed that cytoglobin deletion accelerated the loss of contractile genes and increased DNA damage. Overall, we show that cytoglobin is actively translocated into the nucleus of vascular smooth muscle cells through a redox signal driven by NOX4. We demonstrate that nuclear cytoglobin heterodimerizes with the non-histone chromatin structural protein HMGB2. Our results are consistent with a previously unknown function by which a non-erythrocytic hemoglobin inhibits DNA damage and regulates gene programs in the vasculature by modulating the genome-wide binding of HMGB2.

Ablative radiotherapy improves survival but does not cure autochthonous mouse models of prostate and colorectal cancer

BACKGROUND

Genetically engineered mouse models (GEMMs) of cancer are powerful tools to study mechanisms of disease progression and therapy response, yet little is known about how these models respond to multimodality therapy used in patients. Radiation therapy (RT) is frequently used to treat localized cancers with curative intent, delay progression of oligometastases, and palliate symptoms of metastatic disease.

METHODS

Here we report the development, testing, and validation of a platform to immobilize and target tumors in mice with stereotactic ablative RT (SART). Xenograft and autochthonous tumor models were treated with hypofractionated ablative doses of radiotherapy.

RESULTS

We demonstrate that hypofractionated regimens used in clinical practice can be effectively delivered in mouse models. SART alters tumor stroma and the immune environment, improves survival in GEMMs of primary prostate and colorectal cancer, and synergizes with androgen deprivation in prostate cancer. Complete pathologic responses were achieved in xenograft models, but not in GEMMs.

CONCLUSIONS

While SART is capable of fully ablating xenografts, it is unable to completely eradicate disease in GEMMs, arguing that resistance to potentially curative therapy can be modeled in GEMMs.

Histone Variants and Their Chaperones in Hematological Malignancies

Epigenetic regulation occurs on the level of compacting DNA into chromatin. The functional unit of chromatin is the nucleosome, which consists of DNA wrapped around a core of histone proteins. While canonical histone proteins are incorporated into chromatin through a replication-coupled process, structural variants of histones, commonly named histone variants, are deposited into chromatin in a replication-independent manner. Specific chaperones and chromatin remodelers mediate the locus-specific deposition of histone variants. Although histone variants comprise one of the least understood layers of epigenetic regulation, it has been proposed that they play an essential role in directly regulating gene expression in health and disease. Here, we review the emerging evidence suggesting that histone variants have a role at different stages of hematopoiesis, with a particular focus on the histone variants H2A, H3, and H1. Moreover, we discuss the current knowledge on how the dysregulation of histone variants can contribute to hematopoietic malignancies.

Cellular hierarchy framework based on single-cell/multi-patient sample sequencing reveals metabolic biomarker PYGL as a therapeutic target for HNSCC

BACKGROUND

A growing body of research has revealed the connection of metabolism reprogramming and tumor progression, yet how metabolism reprogramming affects inter-patient heterogeneity and prognosis in head and neck squamous cell carcinoma (HNSCC) still requires further explorations.

METHODS

A cellular hierarchy framework based on metabolic properties discrepancy, METArisk, was introduced to re-analyze the cellular composition from bulk transcriptomes of 486 patients through deconvolution utilizing single-cell reference profiles from 25 primary and 8 metastatic HNSCC sample integration of previous studies. Machine learning methods were used to identify the correlations between metabolism-related biomarkers and prognosis. The functions of the genes screened out in tumor progression, metastasis and chemotherapy resistance were validated in vitro by cellular functional experiments and in vivo by xenograft tumor mouse model.

RESULTS

Incorporating the cellular hierarchy composition and clinical properties, the METArisk phenotype divided multi-patient cohort into two classes, wherein poor prognosis of METArisk-high subgroup was associated with a particular cluster of malignant cells with significant activity of metabolism reprogramming enriched in metastatic single-cell samples. Subsequent analysis targeted for phenotype differences between the METArisk subgroups identified PYGL as a key metabolism-related biomarker that enhances malignancy and chemotherapy resistance by GSH/ROS/p53 pathway, leading to poor prognosis of HNSCC.

CONCLUSION

PYGL was identified as a metabolism-related oncogenic biomarker that promotes HNSCC progression, metastasis and chemotherapy resistance though GSH/ROS/p53 pathway. Our study revealed the cellular hierarchy composition of HNSCC from the cell metabolism reprogramming perspective and may provide new inspirations and therapeutic targets for HNSCC in the future.

Fenofibrate attenuates the cytotoxic effect of cisplatin on lung cancer cells by enhancing the antioxidant defense system in vitro

Fenofibrate (FF) is a peroxisome proliferator- activated receptor (PPAR)-α agonist that is widely used for the treatment of hyperlipidemia. It has been shown to have pleiotropic actions beyond its hypolipidemic effect. FF has been shown to exert a cytotoxic effect on some cancer cells when used at higher than clinically relevant concentrations; on the other hand, its cytoprotective effect on normal cells has also been reported. The present study assessed the effect of FF on cisplatin (CDDP) cytotoxicity to lung cancer cells in vitro. The results demonstrated that the effect of FF on lung cancer cells depends on its concentration. FF at ≤50 µM, which is a clinically achievable blood concentration, attenuated CDDP cytotoxicity to lung cancer cells, whereas FF at ≥100 µM, albeit clinically unachievable, had an anticancer effect. The mechanism of FF attenuation of CDDP cytotoxicity involved PPAR-α-dependent aryl hydrocarbon receptor (AhR) expression, which in turn stimulated nuclear factor erythroid 2-related factor 2 (Nrf2) expression and antioxidant production, resulting in lung cancer cell protection from CDDP-evoked oxidative damage. In conclusion, the present study revealed that FF, at clinically relevant concentrations, attenuated CDDP cytotoxicity to lung cancer cells by enhancing the antioxidant defense system through activation of a pathway that involves the PPAR-α-PPAR response element-AhR xenobiotic response element-Nrf2-antioxidant response element. These findings suggested that concomitant use of FF with CDDP may compromise the efficacy of chemotherapy. Although the anticancer property of FF has recently attracted much attention, concentrations that exceed clinically relevant concentrations are required.

Regulating electron transportation by tungsten oxide nanocapacitors for enhanced radiation therapy

In the process of radiation therapy (RT), the cytotoxic effects of excited electrons generated from water radiolysis tend to be underestimated due to multiple biochemical factors, particularly the recombination between electrons and hydroxyl radicals (·OH). To take better advantage of radiolytic electrons, we constructed WO₃ nanocapacitors that reversibly charge and discharge electrons to regulate electron transportation and utilization. During radiolysis, WO₃ nanocapacitors could contain the generated electrons that block electron-·OH recombination and contribute to the yield of ·OH at a high level. These contained electrons could be discharged from WO₃ nanocapacitors after radiolysis, resulting in the consumption of cytosolic NAD⁺ and impairment of NAD⁺-dependent DNA repair. Overall, this strategy of nanocapacitor-based radiosensitization improves the radiotherapeutic effects by increasing the utilization of radiolytic electrons and ·OH, warranting further validation in multiple tumour models and preclinical experiments.

Reprogramming of the tumor microenvironment using a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic PDT, NO, and radiosensitization therapy of breast cancer and improving anti-tumor immunity

The low X-ray attenuation coefficient of tumor soft tissue and the hypoxic tumor microenvironment (TME) during radiation therapy (RT) of breast cancer result in RT resistance and thus reduced therapeutic efficacy. In addition, immunosuppression induced by the TME severely limits the antitumor immunity of radiation therapy. In this paper, we propose a PCN-224@IrNCs/D-Arg nanoplatform for the synergistic radiosensitization, photodynamic, and NO therapy of breast cancer that also boosts antitumor immunity (PCN = porous coordination network, IrNCs = iridium nanocrystals, D-Arg = D-arginine). The local tumors can be selectively ablated via reprogramming the tumor microenvironment (TME), photodynamic therapy (PDT) and NO therapy, and the presence of the high-Z element Ir that sensitizes radiotherapy. The synergistic execution of these treatment modalities also resulted in adapted antitumor immune response. The intrinsic immunomodulatory effects of the nanoplatform also repolarize macrophages toward the M1 phenotype and induce dendritic cell maturation, activating antitumor T cells to induce immunogenic cell death as demonstrated in vitro and in vivo. The nanocomposite design reported herein represents a new regimen for the treatment of breast cancer through TME reprogramming to exert a synergistic effect for effective cancer therapy and antitumor immunity.

Triptolide enhances carboplatin-induced apoptosis by inhibiting nucleotide excision repair (NER) activity in melanoma

Introduction: Carboplatin (CBP) is a DNA damaging drug used to treat various cancers, including advanced melanoma. Yet we still face low response rates and short survival due to resistance. Triptolide (TPL) is considered to have multifunctional antitumor effects and has been confirmed to enhance the cytotoxic effects of chemotherapeutic drugs. Herein, we aimed to investigate the knowledge about the effects and mechanisms for the combined application of TPL and CBP against melanoma. Methods: Melanoma cell lines and xenograft mouse model were used to uncover the antitumor effects and the underlying molecular mechanisms of the alone or combined treatment of TPL and CBP in melanoma. Cell viability, migration, invasion, apoptosis, and DNA damage were detected by conventional methods. The rate-limiting proteins of the NER pathway were quantitated using PCR and Western blot. Fluorescent reporter plasmids were used to test the NER repair capacity. Results: Our results showed that the presence of TPL in CBP treatment could selectively inhibit NER pathway activity, and TPL exerts a synergistic effect with CBP to inhibit viability, migration, invasion, and induce apoptosis of A375 and B16 cells. Moreover, combined treatment with TPL and CBP significantly inhibited tumor progression in nude mice by suppressing cell proliferation and inducing apoptosis. Discussion: This study reveals the NER inhibitor TPL which has great potential in treating melanoma, either alone or in combination with CBP.

Reduced YAP1 and FOLR1 in gliomas predict better response to chemotherapeutics

Gliomas harbouring mutations in IDH1 (isocitrate dehydrogenase 1) are characterized by greater sensitivity to chemotherapeutics. These mutants also exhibit diminished levels of transcriptional coactivator YAP1 (yes-associated protein 1). Enhanced DNA damage in IDH1 mutant cells, as evidenced by γH2AX formation (phosphorylation of histone variant H2A.X) and ATM (serine/threonine kinase; ataxia telangiectasia mutated) phosphorylation, was accompanied by reduced FOLR1 (folate receptor 1) expression. Diminished FOLR1, concomitant with heightened γH2AX levels, was also observed in patient-derived IDH1 mutant glioma tissues. Chromatin immunoprecipitation, overexpression of mutant YAP1, and treatment with YAP1-TEAD (TEA domain transcription factors) complex inhibitor verteporfin demonstrated regulation of FOLR1 expression by YAP1 and its partner transcription factor TEAD2. TCGA (The Cancer Genome Atlas) data analysis demonstrated better patient survival with reduced FOLR1 expression. Depletion of FOLR1 rendered IDH1 wild-type gliomas more susceptible to temozolomide-mediated death. Despite heightened DNA damage, IDH1 mutants exhibited reduced levels of IL6 (interleukin 6) and IL8 (interleukin 8) - pro-inflammatory cytokines known to be associated with persistent DNA damage. While both FOLR1 and YAP1 influenced DNA damage, only YAP1 was involved in regulating IL6 and IL8. ESTIMATE and CIBERSORTx analyses revealed the association between YAP1 expression and immune cell infiltration in gliomas. By identifying the influence of YAP1-FOLR1 link in DNA damage, our findings suggest that simultaneous depletion of both could amplify the potency of DNA damaging agents, while concomitantly reducing the release of inflammatory mediators and potentially affecting immune modulation. This study also highlights the novel role of FOLR1 as a probable prognostic marker in gliomas, predicting responsiveness to temozolomide and other DNA damaging agents.

Post-translational modifications of histones: Mechanisms, biological functions, and therapeutic targets

Histones are DNA-binding basic proteins found in chromosomes. After the histone translation, its amino tail undergoes various modifications, such as methylation, acetylation, phosphorylation, ubiquitination, malonylation, propionylation, butyrylation, crotonylation, and lactylation, which together constitute the "histone code." The relationship between their combination and biological function can be used as an important epigenetic marker. Methylation and demethylation of the same histone residue, acetylation and deacetylation, phosphorylation and dephosphorylation, and even methylation and acetylation between different histone residues cooperate or antagonize with each other, forming a complex network. Histone-modifying enzymes, which cause numerous histone codes, have become a hot topic in the research on cancer therapeutic targets. Therefore, a thorough understanding of the role of histone post-translational modifications (PTMs) in cell life activities is very important for preventing and treating human diseases. In this review, several most thoroughly studied and newly discovered histone PTMs are introduced. Furthermore, we focus on the histone-modifying enzymes with carcinogenic potential, their abnormal modification sites in various tumors, and multiple essential molecular regulation mechanism. Finally, we summarize the missing areas of the current research and point out the direction of future research. We hope to provide a comprehensive understanding and promote further research in this field.

Immunostimulation with chemotherapy of a ruthenium-arene complex via blockading CD47 signal in chronic myelogenous leukemia cells

Combination of novel immunomodulation and traditional chemotherapy has become a new tendency in cancer treatment. Increasing evidence suggests that blocking the "don't eat me" signal transmitted by the CD47 can promote the phagocytic ability of macrophages to cancer cells, which might be promising for improved cancer chemoimmunotherapy. In this work, we conjugated CPI-alkyne modified by Devimistat (CPI-613) with ruthenium-arene azide precursor Ru-N₃ by copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction to construct Ru complex CPI-Ru. CPI-Ru exhibited satisfactory cytotoxicity towards the K562 cells while nearly non-toxic towards the normal HLF cells. CPI-Ru has been demonstrated to cause severe damage to mitochondria and DNA, ultimately inducing cancer cell death through the autophagic pathway. Moreover, CPI-Ru could significantly downregulate the expression of CD47 on the surface of K562 accompanied by the enhanced immune response by targeting the blockade of CD47. This work provides a new strategy for utilizing metal-based anticancer agents to block CD47 signal to achieve chemoimmunotherapy in chronic myeloid leukemia treatment.

CEP55 as a promising biomarker and therapeutic target on gallbladder cancer

Introduction

Gallbladder cancer (GBC) is a highly malignant biliary tumor with a poor prognosis. As existing therapies for advanced metastatic GBC are rarely effective, there is an urgent need to identify more effective targets for treatment.

Methods

Hub genes of GBC were identified by bioinformatics analysis and their expression in GBC was analyzed by tissue validation. The biological role of CEP55 in GBC cell and the underlying mechanism of the anticancer effect of CEP55 knockdown were evaluated via CCK8, colony formation assay, EDU staining, flow cytometry, western blot, immunofluorescence, and an alkaline comet assay.

Results

We screened out five hub genes of GBC, namely PLK1, CEP55, FANCI, NEK2 and PTTG1. CEP55 is not only overexpressed in the GBC but also correlated with advanced TNM stage, differentiation grade and poorer survival. After CEP55 knockdown, the proliferation of GBC cells was inhibited with cell cycle arrest in G2/M phase and DNA damage. There was a marked increase in the apoptosis of GBC cells in the siCEP55 group. Besides, in vivo, CEP55 inhibition attenuated the growth and promoted apoptosis of GBC cells. Mechanically, the tumor suppressor effect of CEP55 knockdown is associated with dysregulation of the AKT and ERK signaling networks.

Discussion

These data not only demonstrate that CEP55 is identified as a potential independent predictor crucial to the diagnosis and prognosis of gallbladder cancer but also reveal the possibility for CEP55 to be used as a promising target in the treatment of GBC.

Nuclear cytoglobin associates with HMGB2 and regulates DNA damage and genome-wide transcriptional output in the vasculature

Identifying novel regulators of vascular smooth muscle cell function is necessary to further understand cardiovascular diseases. We previously identified cytoglobin, a hemoglobin homolog, with myogenic and cytoprotective roles in the vasculature. The specific mechanism of action of cytoglobin is unclear but does not seem to be related to oxygen transport or storage like hemoglobin. Herein, transcriptomic profiling of injured carotid arteries in cytoglobin global knockout mice revealed that cytoglobin deletion accelerated the loss of contractile genes and increased DNA damage. Overall, we show that cytoglobin is actively translocated into the nucleus of vascular smooth muscle cells through a redox signal driven by NOX4. We demonstrate that nuclear cytoglobin heterodimerizes with the non-histone chromatin structural protein HMGB2. Our results are consistent with a previously unknown function by which a non-erythrocytic hemoglobin inhibits DNA damage and regulates gene programs in the vasculature by modulating the genome-wide binding of HMGB2.

cRGD-targeted heparin nanoparticles for effective dual drug treatment of cisplatin-resistant ovarian cancer

Resistance to the chemotherapeutic agent cisplatin (DDP) is the primary reason for invalid chemotherapy of ovarian cancer. Given the complex mechanisms underlying chemo-resistance, the design of combination therapies based on blocking multiple mechanisms is a rationale to synergistically elevate therapeutic effect for effectively overcoming cancer chemo-resistance. Herein, we demonstrated a multifunctional nanoparticle (DDP-Ola@HR), which could simultaneously co-deliver DDP and Olaparib (Ola, DNA damage repair inhibitor) using targeted ligand cRGD peptide modified with heparin (HR) as nanocarrier, enabling the concurrent tackling of multiple resistance mechanisms to effectively inhibit the growth and metastasis of DDP-resistant ovarian cancer. In combination strategy, heparin could suppress the function of multidrug resistance-associated protein 2 (MRP2) and P-glycoprotein (P-gp) to promote the intracellular accumulation of DDP and Ola by specifically binding with heparanase (HPSE) to down-regulate PI3K/AKT/mTOR signaling pathway, and simultaneously served as a carrier combined with Ola to synergistically enhance the anti-proliferation ability of DDP for resistant ovarian cancer, thus achieving great therapeutic efficacy. Our DDP-Ola@HR could provide a simple and multifunctional combination strategy to trigger an anticipated cascading effect, thus effectively overcoming the chemo-resistance of ovarian cancer.

Plumbagin Exhibits Genotoxicity and Induces G2/M Cell Cycle Arrest via ROS-Mediated Oxidative Stress and Activation of ATM-p53 Signaling Pathway in Hepatocellular Cells

Plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone, PLB), a naturally occurring naphthoquinone mainly isolated from the plant Plumbago zeylanica L., has been proven to possess anticancer activities towards multiple types of cancer. Although there has been an increasing amount of research regarding its anticancer effects, the association between oxidative stress, genotoxicity and the cell cycle arrest induced by PLB still remains unclear. Therefore, it is important to investigate their potential connections and the involvement of DNA damage and the ataxia telangiectasia mutated protein (ATM)-p53 signaling pathway in PLB’s anticancer mechanism. The present study showed that PLB exposure significantly reduced HCC cell viability and colony formation. In addition, PLB-induced G2/M cell cycle arrest, oxidative stress, and DNA damage was detected, which could be almost blocked by NAC pretreatment. PLB could trigger a DNA damage response by activating cell cycle checkpoints such as ATM, checkpoint kinase 1 (Chk1), checkpoint kinase 2 (Chk2) and p53. Meanwhile, the key modulator of the G2/M transition factor, Cell Division Cycle 25C (cdc25C), was significantly downregulated in an ROS-dependent manner. Furthermore, pretreatment with ATM and p53 inhibitors (KU55933 and Pifithrin-α) could reduce the occurrence of G2/M cell cycle arrest by inhibiting the activation of the ATM-p53 pathway. Taken together, these results indicate that ROS-mediated oxidative stress plays a key role in PLB-induced G2/M cell cycle arrest mediated by the ATM-p53 pathway.

Visualizing DNA Damage Repair Proteins in Patient-Derived Ovarian Cancer Organoids via Immunofluorescence Assays

Immunofluorescence is one of the most widely used techniques to visualize target antigens with high sensitivity and specificity, allowing for the accurate identification and localization of proteins, glycans, and small molecules. While this technique is well-established in two-dimensional (2D) cell culture, less is known about its use in three-dimensional (3D) cell models. Ovarian cancer organoids are 3D tumor models that recapitulate tumor cell clonal heterogeneity, the tumor microenvironment, and cell-cell and cell-matrix interactions. Thus, they are superior to cell lines for the evaluation of drug sensitivity and functional biomarkers. Therefore, the ability to utilize immunofluorescence on primary ovarian cancer organoids is extremely beneficial in understanding the biology of this cancer. The current study describes the technique of immunofluorescence to detect DNA damage repair proteins in high-grade serous patient-derived ovarian cancer organoids (PDOs). After exposing the PDOs to ionizing radiation, immunofluorescence is performed on intact organoids to evaluate nuclear proteins as foci. Images are collected using z-stack imaging on confocal microscopy and analyzed using automated foci counting software. The described methods allow for the analysis of temporal and special recruitment of DNA damage repair proteins and colocalization of these proteins with cell-cycle markers.

Graphene Oxide Nanosheets Reduce Astrocyte Reactivity to Inflammation and Ameliorate Experimental Autoimmune Encephalomyelitis

In neuroinflammation, astrocytes play multifaceted roles that regulate the neuronal environment. Astrocytes sense and respond to pro-inflammatory cytokines (CKs) and, by a repertoire of intracellular Ca²⁺ signaling, contribute to disease progression. Therapeutic approaches wish to reduce the overactivation in Ca²⁺ signaling in inflammatory-reactive astrocytes to restore dysregulated cellular changes. Cell-targeting therapeutics might take advantage by the use of nanomaterial-multifunctional platforms such as graphene oxide (GO). GO biomedical applications in the nervous system involve therapeutic delivery and sensing, and GO flakes were shown to enable interfacing of neuronal and glial membrane dynamics. We exploit organotypic spinal cord cultures and optical imaging to explore Ca²⁺ changes in astrocytes, and we report, when spinal tissue is exposed to CKs, neuroinflammatory-associated modulation of resident glia. We show the efficacy of GO to revert these dynamic changes in astrocytic reactivity to CKs, and we translate this potential in an animal model of immune-mediated neuroinflammatory disease.

Genistein and Procyanidin B2 Reduce Carcinogen-Induced Reactive Oxygen Species and DNA Damage through the Activation of Nrf2/ARE Cell Signaling in Bronchial Epithelial Cells In Vitro

Cancer is one of the leading causes of death worldwide. Chemotherapy and radiation therapy are currently providing the basis for cancer therapies, although both are associated with significant side effects. Thus, cancer prevention through dietary modifications has been receiving growing interest. The potential of selected flavonoids in reducing carcinogen-induced reactive oxygen species (ROS) and DNA damage through the activation of nuclear factor erythroid 2 p45 (NF-E2)-related factor (Nrf2)/antioxidant response element (ARE) pathway was studied in vitro. Dose-dependent effects of pre-incubated flavonoids on pro-carcinogen 4-[(acetoxymethyl)nitrosamino]-1-(3-pyridyl)-1-butanone (NNKAc)-induced ROS and DNA damage in human bronchial epithelial cells were studied in comparison to non-flavonoids. The most effective flavonoids were assessed for the activation of Nrf2/ARE pathway. Genistein, procyanidin B2 (PCB2), and quercetin significantly suppressed the NNKAc-induced ROS and DNA damage. Quercetin significantly upregulated the phosphorylated protein kinase B/Akt. PCB2 significantly upregulated the activation of Nrf2 and Akt through phosphorylation. Genistein and PCB2 significantly upregulated the phospho-Nrf2 nuclear translocation and catalase activity. In summary, genistein and PCB2 reduced the NNKAc-induced ROS and DNA damage through the activation of Nrf2. Further studies are required to understand the role of dietary flavonoids on the regulation of the Nrf2/ARE pathway in relation to carcinogenesis.

Synergetic effect of high dose rate radiations (10× FFF/2400 MU/min/10 MV x-rays) and paclitaxel selectively eliminates melanoma cells

BACKGROUND

Melanoma is one of the most aggressive cancers, with 1.6% of total cancer deaths in the United States. In recent years treatment options for metastatic melanoma have been improved by the FDA approval of new therapeutic agents. However, these inhibitors-based therapies are non-specific and have severe toxicities, including hyperkeratosis, photosensitivity, hepatitis, arthralgia, and fatigue.

AIMS

The aim of this study is to determine the synthetic lethal effect (paclitaxel and radiations) on melanoma cells and reduce the total radiation doses by increasing the dose rates up to 2400 MU/min.

METHODS AND RESULTS

We previously reported a radiation treatment (10 MV x-rays, 10X-FFF, dose rate 2400MU/min, low total dose 0.5 Gy) that kills melanoma cells with 80% survival of normal HEM in vitro. In this study, we extended the radiation cycle up to four and included paclitaxel treatment to study the synthetic lethal effect on melanoma and two other normal primary cells, HDF and HEK. Cells were treated with paclitaxel prior to the radiation at a dose rate of 400 and 2400 MU/min with a total radiation dose of only 0.5 Gy. Mitochondrial respiration assay, DNA damage assay, and colony formation assays were performed to study apoptosis and cell death induction. Four days of consequent radiation treatment with paclitaxel significantly reduces the survival of melanoma cells by inducing apoptosis and mitochondrial damage. After treatment, excessive DNA damage in melanoma cells leads to an increase in the expression of pro-apoptotic genes (Caspase-3) and a decrease in the expression of DNA repair gene (PARP1) and anti-apoptotic gene (Bcl-2) to activate the apoptosis pathway. The combination of paclitaxel and radiation reduces the survival of melanoma cells colonies compared to radiation alone.

CONCLUSION

Our study indicates that radiations with paclitaxel have a potential synthetic lethal effect on melanoma cells and can be developed as a melanoma therapy without toxicities or harmful effects on normal primary skin cells.

Traffic-Related Air Pollution and Ground-Level Ozone Associated Global DNA Hypomethylation and Bulky DNA Adduct Formation

Studies have indicated that air pollution, including surface-level ozone (O₃), can significantly influence the risk of chronic diseases. To better understand the carcinogenic mechanisms of air pollutants and identify predictive disease biomarkers, we examined the association between traffic-related pollutants with DNA methylation alterations and bulky DNA adducts, two biomarkers of carcinogen exposure and cancer risk, in the peripheral blood of 140 volunteers-95 traffic police officers, and 45 unexposed subjects. The DNA methylation and adduct measurements were performed by bisulfite-PCR and pyrosequencing and ³²P-postlabeling assay. Airborne levels of benzo(a)pyrene [B(a)P], carbon monoxide, and tropospheric O₃ were determined by personal exposure biomonitoring or by fixed monitoring stations. Overall, air pollution exposure was associated with a significant reduction (1.41 units) in global DNA methylation (95% C.I. -2.65-0.04, p = 0.026). The decrement in ALU repetitive elements was greatest in the policemen working downtown (95% C.I. -3.23--0.49, p = 0.008). The DNA adducts were found to be significantly increased (0.45 units) in the municipal officers with respect to unexposed subjects (95% C.I. 0.02-0.88, p = 0.039), mainly in those who were controlling traffic in downtown areas (95% C.I. 0.39-1.29, p < 0.001). Regression models indicated an increment of ALU methylation at higher B(a)P concentrations (95% C.I. 0.03-0.60, p = 0.032). Moreover, statistical models showed a decrement in ALU methylation and an increment of DNA damage only above the cut-off value of 30 µg/m³ O₃. A significant increment of 0.73 units of IL-6 gene methylation was also found in smokers with respect to non-smokers. Our results highlighted the role of air pollution on epigenetic alterations and genotoxic effects, especially above the target value of 30 µg/m³ surface-level O₃, supporting the necessity for developing public health strategies aimed to reduce traffic-related air pollution molecular alterations.

Platinum-Based TREM2 Inhibitor Suppresses Tumors by Remodeling the Immunosuppressive Microenvironment

Triggering receptor expressed on myeloid cells-2 (TREM2) is a key pro-tumorigenic marker of tumor-infiltrating macrophages, showing potent immunosuppressive activity in tumor microenvironment. A platinum(IV) complex OPA derived from oxaliplatin (OP) and artesunate (ART) exhibited direct cytotoxicity against human colon cancer cells and immunomodulatory activity to inhibit TREM2 on macrophages in vitro and vivo. Furthermore, OPA deterred the tumor growth in mouse models bearing MC38 colorectal tumor by reducing the number of CD206⁺ and CX₃ CR1⁺ immunosuppressive macrophages; it also promoted the expansion and infiltration of immunostimulatory dendritic, cytotoxic T, and natural killer cells. OPA is the first small-molecular TREM2 inhibitor capable of relieving immunosuppressive tumor microenvironment and enhancing chemical anticancer efficiency of a platinum drug, thus showing typical characteristics of a chemoimmunotherapeutic agent.

A Cascade Targeted and Mitochondrion-Dysfunctional Nanomedicine Capable of Overcoming Drug Resistance in Hepatocellular Carcinoma

Chemoresistance is a formidable issue in clinical anticancer therapy and is pertinent to the lowered efficacies of chemotherapeutics and the activated tumor self-repairing proceedings. Herein, bifunctional amphiphiles containing galactose ligands and high-density disulfide are synthesized for encapsulating mitochondrion-targeting tetravalent platinum prodrugs to construct a cascade targeted and mitochondrion-dysfunctional nanomedicine (Gal-NP@TPt). Subsequent investigations verify that Gal-NP@TPt with sequential targeting functions toward tumors and mitochondria improved the spatiotemporal level of platinum. In addition, glutathione depletion by Gal-NP@TPt appear to substantially inhibit the proceedings of platinum detoxification, inducing the susceptibility to the mitochondrial platinum. Moreover, the strategic transportation of platinum to mitochondria lacking DNA repair machinery by Gal-NP@TPt lowers the possibility of platinum deactivation. Eventually, Gal-NP@TPt demonstrates appreciable antitumor effects for the systemic treatment of patient-derived tumor xenografts of hepatocellular carcinoma. Note that these strategies in overcoming drug resistance have also been confirmed to be valid based on genome-wide analysis via RNA-sequencing. Therefore, an intriguing multifunctional nanomedicine capable of resolving formidable chemoresistance is achieved, which should be greatly emphasized in practical applications for the treatment of intractable tumors.

Upregulated DNA Damage-Linked Biomarkers in Parkinson's Disease Model Mice

SUMMARY STATEMENT

The present study examined expression of DNA damage markers in VMAT2 Lo PD model mice. The results demonstrate there is a significant increase in these DNA damage markers mostly in the brain regions of 18- and 23-month-old model mice, indicating oxidative stress-induced DNA lesion is an important pathologic feature of this mouse model.

Factors to Consider for the Correct Use of γH2AX in the Evaluation of DNA Double-Strand Breaks Damage Caused by Ionizing Radiation

People exposed to ionizing radiation (IR) both for diagnostic and therapeutic purposes is constantly increasing. Since the use of IR involves a risk of harmful effects, such as the DNA DSB induction, an accurate determination of this induced DNA damage and a correct evaluation of the risk-benefit ratio in the clinical field are of key relevance. γH2AX (the phosphorylated form of the histone variant H2AX) is a very early marker of DSBs that can be induced both in physiological conditions, such as in the absence of specific external agents, and by external factors such as smoking, heat, background environmental radiation, and drugs. All these internal and external conditions result in a basal level of γH2AX which must be considered for the correct assessment of the DSBs after IR exposure. In this review we analyze the most common conditions that induce H2AX phosphorylation, including specific exogenous stimuli, cellular states, basic environmental factors, and lifestyles. Moreover, we discuss the most widely used methods for γH2AX determination and describe the principal applications of γH2AX scoring, paying particular attention to clinical studies. This knowledge will help us optimize the use of available methods in order to discern the specific γH2AX following IR-induced DSBs from the basal level of γH2AX in the cells.