N6-Methyladenosine (m6A) modification activates serine synthesis pathway to mediate therapeutic resistance in liver cancer.

Metabolic adaptation serves as a significant driving force for cancer growth and poses a substantial obstacle for cancer therapies. Herein, we unravelled the role of m6A -mediated serine synthesis pathway regulation in both hepatocellular carcinoma (HCC) development and therapeutic resistance. We demonstrated that the highly specific m6A inhibitor (STM2457) treatment effectively inhibited HCC cell line growth and suppressed spontaneous HCC formation in mice driven by liver specific Tp53 knockout and Myc overexpression. Using GLORI-seq, we delineated a single-base resolution m6A landscape in human HCC cell lines. Interestingly, we identified three core enzymes in the serine synthesis pathway (PHGDH, PSAT1, and PSPH) as novel targets of METTL3-mediated m6A modification. In these SSP genes, m6A modification recruited IGF2BP3 reader to stabilize their mRNA transcripts, thereby enhancing their mRNA and protein expression in HCC cells. Most importantly, our GLORI-seq data revealed that sorafenib-resistant HCC cells elevated m6A modification in SSP genes to promote protein expression and antioxidant production. STM2457 treatment attenuated the serine synthesis pathway, induced oxidative stress, and sensitized HCC cells to sorafenib and lenvatinib treatments. In conclusion, our findings suggest that targeting m6A could be a potential therapeutic strategy for HCC treatment.

Cell cycle inhibitors activate hypoxia-induced DDX41-STING pathway to mediate anti-tumor immune response in liver cancer.

Cell cycle inhibitors have a long history as cancer treatment. Here, we reported that these inhibitors combated cancer partially via Stimulator of IFN genes (STING) signaling pathway. We demonstrated that Paclitaxel (microtubule stabilizer), Palbociclib (cyclin dependent kinase 4/6 inhibitor), AZD1152 and GSK1070916 (aurora kinase B inhibitors) have anti-cancer functions beyond arresting cell cycle. They consistently caused cytosolic DNA accumulation and DNA damage, which inadvertently triggered the cytosolic DNA sensor DEAD-box helicase 41 (DDX41) and activated STING to secrete pro-inflammatory senescence-associated secretory phenotype factors (SASPs). Interestingly, we found that DDX41 was a transcriptional target of HIF. Hypoxia induced expression of DDX41 through HIF-1, making hypoxic HCC cells more sensitive to the anti-mitotic agents in STING activation and SASP production. The SASPs triggered immune cell infiltration in tumors for cancer clearance. The treatment of cell cycle inhibitors, especially Paclitaxel, extends survival by perturbing mouse HCC growth when used in combination with anti-PD-1. We observed a trend that Paclitaxel suppressed STINGWT HCC more effectively than STINGKO HCC, suggesting that STING might contribute to the anti-tumor effects of Paclitaxel. Our study revealed the immune-mediated tumor-suppressing properties of cell cycle inhibitors and suggested combined treatment with immunotherapy as a potential therapeutic approach.

The immune microenvironment of steatotic hepatocellular carcinoma: Current findings and future prospects.

Hepatocellular carcinoma (HCC), the major type of primary liver cancer, is notorious for its resistance to systemic treatments. The field has made a great leap in the past decade, with the number of FDA-approved therapies for advanced HCC increasing from 1 to 9. Although tyrosine kinase inhibitors remain the most common first-line option as monotherapy treatment, the clinical success of immune checkpoint inhibitors, especially when used in combination with anti-VEGF/VEGFR in HCC will likely transform the treatment landscape. While immune checkpoint inhibitors represent an exciting therapeutic revenue for HCC, recent studies have revealed that nonviral HCC, which is primarily caused by metabolic dysfunction-associated steatotic hepatitis (MASH), has a distinct and less favorable response to the immune checkpoint inhibitors. MASH is the most rapidly increasing etiology for HCC. The immune microenvironment of MASH-HCC is greatly affected by the intertwined pathological processes of steatosis-induced iterative cycles between steatohepatitis and liver injury. Here, we present a timely summary of the immune microenvironment of MASH-HCC. We will delve into the use of cutting-edge technologies, such as single-cell RNA sequencing, spatial transcriptomics, and mass cytometry imaging, to deconvolute the complexity of the immune ecosystem in MASH-HCC. We will also discuss the novel therapeutic innovations for MASH-HCC in preclinical models, such as the metabolic inhibitor, epigenetic inhibitor, and immunomodulator. These inhibitors all have the ability to subvert the immune microenvironment of MASH-HCC, improving the efficiency of anti-PD-1. While awaiting new drugs to be tested in clinical trials, the knowledge gained from these investigations is crucial for the development of personalized and effective treatment strategies for MASH-HCC.

Gut enterotype-dependent modulation of gut microbiota and their metabolism in response to xanthohumol supplementation in healthy adults.

Xanthohumol (XN), a polyphenol found in the hop plant (Humulus lupulus), has antioxidant, anti-inflammatory, prebiotic, and anti-hyperlipidemic activity. Preclinical evidence suggests the gut microbiome is essential in mediating these bioactivities; however, relatively little is known about XN's impact on human gut microbiota in vivo. We conducted a randomized, triple-blinded, placebo-controlled clinical trial (ClinicalTrials.gov NCT03735420) to determine safety and tolerability of XN in healthy adults. Thirty healthy participants were randomized to 24 mg/day XN or placebo for 8 weeks. As secondary outcomes, quantification of bacterial metabolites and 16S rRNA gene sequencing were utilized to explore the relationships between XN supplementation, gut microbiota, and biomarkers of gut health. Although XN did not significantly change gut microbiota composition, it did re-shape individual taxa in an enterotype-dependent manner. High levels of inter-individual variation in metabolic profiles and bioavailability of XN metabolites were observed. Moreover, reductions in microbiota-derived bile acid metabolism were observed, which were specific to Prevotella and Ruminococcus enterotypes. These results suggest interactions between XN and gut microbiota in healthy adults are highly inter-individualized and potentially indicate that XN elicits effects on gut health in an enterotype-dependent manner.

Bone Marrow Adipose Tissue Is Not Required for Reconstitution of the Immune System Following Irradiation in Male Mice.

Bone marrow adipose tissue (BMAT) is hypothesized to serve as an expandable/contractible fat depot which functions, in part, to minimize energy requirements for sustaining optimal hematopoiesis. We investigated whether BMAT is required for immune reconstitution following injury. Male wild type (WBB6F1, WT) and BMAT-deficient WBB6F1/J-KitW/KitW-v/J (KitW/W-v) mice were lethally irradiated. Irradiation was followed by adoptive transfer of 1000 purified WT hematopoietic stem cells (HSCs). The extent of immune reconstitution in blood, bone marrow, and lymph nodes in the irradiated mice was determined using HSCs from green fluorescent protein (GFP)-expressing mice. We also evaluated skeletal response to treatment. Detection of GFP-positive B and T cells in peripheral blood at 4 and 9 weeks following adoptive transfer and in bone marrow and lymph nodes following necropsy revealed excellent immune reconstitution in both WT and BMAT-deficient mice. Adipocytes were numerous in the distal femur of WT mice but absent or rare in KitW/W-v mice. Bone parameters, including length, mass, density, bone volume, microarchitecture, and turnover balance, exhibited few differences between WT and BMAT-deficient mice. The minimal differences suggest that BMAT is not required for reconstitution of the immune system following lethal radiation and is not a major contributor to the skeletal phenotypes of kit signaling-deficient mice.

The dePARylase NUDT16 promotes radiation resistance of cancer cells by blocking SETD3 for degradation via reversing its ADP-ribosylation.

Poly(ADP-ribosyl)ation (PARylation) is a critical posttranslational modification that plays a vital role in maintaining genomic stability via a variety of molecular mechanisms, including activation of replication stress and the DNA damage response. The nudix hydrolase NUDT16 was recently identified as a phosphodiesterase that is responsible for removing ADP-ribose units and that plays an important role in DNA repair. However, the roles of NUDT16 in coordinating replication stress and cell cycle progression remain elusive. Here, we report that SETD3, which is a member of the SET-domain containing protein (SETD) family, is a novel substrate for NUDT16, that its protein levels fluctuate during cell cycle progression, and that its stability is strictly regulated by NUDT16-mediated dePARylation. Moreover, our data indicated that the E3 ligase CHFR is responsible for the recognition and degradation of endogenous SETD3 in a PARP1-mediated PARylation-dependent manner. Mechanistically, we revealed that SETD3 associates with BRCA2 and promotes its recruitment to stalled replication fork and DNA damage sites upon replication stress or DNA double-strand breaks, respectively. Importantly, depletion of SETD3 in NUDT16-deficient cells did not further exacerbate DNA breaks or enhance the sensitivity of cancer cells to IR exposure, suggesting that the NUDT16-SETD3 pathway may play critical roles in the induction of tolerance to radiotherapy. Collectively, these data showed that NUDT16 functions as a key upstream regulator of SETD3 protein stability by reversing the ADP-ribosylation of SETD3, and NUDT16 participates in the resolution of replication stress and facilitates HR repair.

Treatment of coronavirus disease 2019-associated mucositis in adolescents: A case report and brief literature review.

Reactive Infectious Mucocutaneous Eruption is an acute mucocutaneous inflammation secondary to an infection with minimal to absent cutaneous features that has recently been linked to the Severe Acute Respiratory Syndrome Coronavirus-19 (SARS-CoV-19 virus). Unfortunately, the relative rarity of case reports of Reactive Infectious Mucocutaneous Eruption in paediatric populations has led to fewer known successful treatment options with the current mainstay being systemic immunosuppression (e.g. corticosteroids, cyclosporine and etanercept). In this case report, we discuss a case of an adolescent patient with (polymerase chain reaction) PCR+ coronavirus disease 2019 infection and an oral eruption without cutaneous symptoms. He was treated successfully using a single dose of dexamethasone and supportive care through amorphous hydrogel (Intrasite gel), thus providing a safe, cheap and effective treatment option in mild coronavirus disease 2019-associated Reactive Infectious Mucocutaneous Eruption in paediatric patients. We also discuss the current findings, diagnostic terms and treatment options of mucosal manifestations of coronavirus disease 2019 in children.

Inhibition of CAF-1 histone chaperone complex triggers cytosolic DNA and dsRNA sensing pathways and induces intrinsic immunity of hepatocellular carcinoma.

BACKGROUND AND AIMS: Chromatin assembly factor 1 (CAF-1) is a replication-dependent epigenetic regulator that controls cell cycle progression and chromatin dynamics. In this study, we aim to investigate the immunomodulatory role and therapeutic potential of the CAF-1 complex in HCC. APPROACH AND RESULTS: CAF-1 complex knockout cell lines were established using the CRISPR/Cas9 system. The effects of CAF-1 in HCC were studied in HCC cell lines, nude mice, and immunocompetent mice. RNA-sequencing, ChIP-Seq, and assay for transposase accessible chromatin with high-throughput sequencing (ATAC-Seq) were used to explore the changes in the epigenome and transcriptome. CAF-1 complex was significantly upregulated in human and mouse HCCs and was associated with poor prognosis in patients with HCC. Knockout of CAF-1 remarkably suppressed HCC growth in both in vitro and in vivo models. Mechanistically, depletion of CAF-1 induced replicative stress and chromatin instability, which eventually led to cytoplasmic DNA leakage as micronuclei. Also, chromatin immunoprecipitation sequencing analyses revealed a massive H3.3 histone variant replacement upon CAF-1 knockout. Enrichment of euchromatic H3.3 increased chromatin accessibility and activated the expression of endogenous retrovirus elements, a phenomenon known as viral mimicry. However, cytosolic micronuclei and endogenous retroviruses are recognized as ectopic elements by the stimulator of interferon genes and dsRNA viral sensing pathways, respectively. As a result, the knockout of CAF-1 activated inflammatory response and antitumor immune surveillance and thereby significantly enhanced the anticancer effect of immune checkpoint inhibitors in HCC. CONCLUSIONS: Our findings suggest that CAF-1 is essential for HCC development; targeting CAF-1 may awaken the anticancer immune response and may work cooperatively with immune checkpoint inhibitor treatment in cancer therapy.

Understanding the microenvironment and how this controls cell fate.

The microenvironment influences cell fate. In this collection of voices, researchers from the fields of cancer and regeneration highlight approaches to establish the importance of the microenvironment and discuss future directions to understand the complex interaction between cells and their surrounding environment and how this impacts on disease and regeneration.

Zinc supplementation alters tissue distribution of arsenic in Mus musculus.

Arsenic occurs naturally in the environment and humans can be exposed through food, drinking water and inhalation of air-borne particles. Arsenic exposure is associated with cardiovascular, pulmonary, renal, immunologic, and developmental toxicities as well as carcinogenesis. Arsenic displays dose-depen toxicities in target organs or tissues with elevated levels of arsenic. Zinc is an essential micronutrient with proposed protective benefits due to its antioxidant properties, integration into zinc-containing proteins and zinc-related immune signaling. In this study, we tested levels of arsenic and zinc in plasma, kidney, liver, and spleen as model tissues after chronic (42-day) treatment with either arsenite, zinc, or in combination. Arsenite exposure had minimal impact on tissue zinc levels with the exception of the kidney. Conversely, zinc supplementation of arsenite-exposed mice reduced the amount of arsenic detected in all tissues tested. Expression of transporters associated with zinc or arsenic influx and efflux were evaluated under each treatment condition. Significant effects of arsenite exposure on zinc transporter expression displayed tissue selectivity for liver and kidney, and was restricted to Zip10 and Zip14, respectively. Arsenite also interacted with zinc co-exposure for Zip10 expression in liver tissue. Pairwise comparisons show neither arsenite nor zinc supplementation alone significantly altered expression of transporters utilized by arsenic. However, significant interactions between arsenite and zinc were evident for Aqp7 and Mrp1 in a tissue selective manner. These findings illustrate interactions between arsenite and zinc leading to changes in tissue metal level and suggest a potential mechanism by which zinc may offer protection from arsenic toxicities.

Inhibition of PLK4 remodels histone methylation and activates the immune response via the cGAS-STING pathway in TP53-mutated AML.

Acute myeloid leukemia (AML) with TP53 mutation is one of the most lethal cancers and portends an extremely poor prognosis. Based on in silico analyses of druggable genes and differential gene expression in TP53-mutated AML, we identified pololike kinase 4 (PLK4) as a novel therapeutic target and examined its expression, regulation, pathogenetic mechanisms, and therapeutic potential in TP53-mutated AML. PLK4 expression was suppressed by activated p53 signaling in TP53 wild-type AML and was increased in TP53-mutated AML cell lines and primary samples. Short-term PLK4 inhibition induced DNA damage and apoptosis in TP53 wild-type AML. Prolonged PLK4 inhibition suppressed the growth of TP53-mutated AML and was associated with DNA damage, apoptosis, senescence, polyploidy, and defective cytokinesis. A hitherto undescribed PLK4/PRMT5/EZH2/H3K27me3 axis was demonstrated in both TP53 wild-type and mutated AML, resulting in histone modification through PLK4-induced PRMT5 phosphorylation. In TP53-mutated AML, combined effects of histone modification and polyploidy activated the cGAS-STING pathway, leading to secretion of cytokines and chemokines and activation of macrophages and T cells upon coculture with AML cells. In vivo, PLK4 inhibition also induced cytokine and chemokine expression in mouse recipients, and its combination with anti-CD47 antibody, which inhibited the "don't-eat-me" signal in macrophages, synergistically reduced leukemic burden and prolonged animal survival. The study shed important light on the pathogenetic role of PLK4 and might lead to novel therapeutic strategies in TP53-mutated AML.

Characteristics and complications of anogenital infantile hemangiomas: A multicenter retrospective analysis.

BACKGROUND: Infantile hemangiomas (IHs) of the anogenital region remain poorly characterized. OBJECTIVE: To examine the distribution, ulceration rate, and associated congenital anomalies of anogenital IHs. METHODS: Retrospective study at 8 tertiary referral centers. RESULTS: A total of 435 infants with an IH of the anogenital region were enrolled (of which, 319 [73%] were girls). Congenital anomalies were present in 6.4% (n = 28) of infants with an anogenital IH. Segmental or partial segmental anogenital IHs ulcerated in 72% (n = 99 of 138) of infants, whereas 45% (n = 133 of 297) of focal anogenital IHs experienced ulceration (P < .001). In a multivariable logistic regression analysis, segmental or partial segmental morphology (adjusted odds ratio [aOR], 2.70; 95% CI, 1.60-4.64), mixed type (aOR, 3.44; 95% CI, 2.01-6.07), and perianal (aOR, 3.01; 95% CI, 1.53-6.12) and buttocks location (aOR, 2.08; 95% CI, 1.17-3.76) had increased odds of ulceration. Segmental or partial segmental IHs of the genitalia were confined to distinct anatomic territories and were predominantly distributed unilaterally, with a linear demarcation at the perineal raphe. LIMITATIONS: Possible selection bias, given recruitment at tertiary referral centers. CONCLUSION: This study improves our understanding of high-risk features of anogenital IHs and demonstrates that genital segmental or partial segmental IHs develop within distinct anatomic territories.

Hypoxia-inducible factor orchestrates adenosine metabolism to promote liver cancer development.

Hypoxia-induced adenosine creates an immunosuppressive tumor microenvironment (TME) and dampens the efficacy of immune checkpoint inhibitors (ICIs). We found that hypoxia-inducible factor 1 (HIF-1) orchestrates adenosine efflux through two steps in hepatocellular carcinoma (HCC). First, HIF-1 activates transcriptional repressor MXI1, which inhibits adenosine kinase (ADK), resulting in the failure of adenosine phosphorylation to adenosine monophosphate. This leads to adenosine accumulation in hypoxic cancer cells. Second, HIF-1 transcriptionally activates equilibrative nucleoside transporter 4, pumping adenosine into the interstitial space of HCC, elevating extracellular adenosine levels. Multiple in vitro assays demonstrated the immunosuppressive role of adenosine on T cells and myeloid cells. Knockout of ADK in vivo skewed intratumoral immune cells to protumorigenic and promoted tumor progression. Therapeutically, combination treatment of adenosine receptor antagonists and anti-PD-1 prolonged survival of HCC-bearing mice. We illustrated the dual role of hypoxia in establishing an adenosine-mediated immunosuppressive TME and offered a potential therapeutic approach that synergizes with ICIs in HCC.

Ferroptosis Suppressor Protein 1 Inhibition Promotes Tumor Ferroptosis and Anti-tumor Immune Responses in Liver Cancer.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) is a highly aggressive malignancy with dreadful clinical outcome. Tyrosine kinase inhibitors and immune checkpoint inhibitors are the only United States Food and Drug Administration-approved therapeutic options for patients with advanced HCC with limited therapeutic success. Ferroptosis is a form of immunogenic and regulated cell death caused by chain reaction of iron-dependent lipid peroxidation. Coenzyme Q10 (CoQ10)/ferroptosis suppressor protein 1 (FSP1) axis was recently identified as a novel protective mechanism against ferroptosis. We would like to explore whether FSP1 could be a potential therapeutic target for HCC. METHODS: FSP1 expression in human HCC and paired non-tumorous tissue samples were determined by reverse transcription-quantitative polymerase chain reaction, followed by clinicopathologic correlation and survival studies. Regulatory mechanism for FSP1 was determined using chromatin immunoprecipitation. The hydrodynamic tail vein injection model was used for HCC induction to evaluate the efficacy of FSP1 inhibitor (iFSP1) in vivo. Single-cell RNA sequencing revealed the immunomodulatory effects of iFSP1 treatment. RESULTS: We showed that HCC cells greatly rely on the CoQ10/FSP1 system to overcome ferroptosis. We found that FSP1 was significantly overexpressed in human HCC and is regulated by kelch-like ECH-associated protein 1/nuclear factor erythroid 2-related factor 2 pathway. FSP1 inhibitor iFSP1 effectively reduced HCC burden and profoundly increased immune infiltrates including dendritic cells, macrophages, and T cells. We also demonstrated that iFSP1 worked synergistically with immunotherapies to suppress HCC progression. CONCLUSIONS: We identified FSP1 as a novel, vulnerable therapeutic target in HCC. The inhibition of FSP1 potently induced ferroptosis, which promoted innate and adaptive anti-tumor immune responses and effectively suppressed HCC tumor growth. FSP1 inhibition therefore represents a new therapeutic strategy for HCC.

PFKFB4 Drives the Oncogenicity in TP53-Mutated Hepatocellular Carcinoma in a Phosphatase-Dependent Manner.

BACKGROUND & AIMS: Metabolic reprogramming is recognized as a cancer hallmark intimately linked to tumor hypoxia, which supports rapid tumor growth and mitigates the consequential oxidative stress. Phosphofructokinase-fructose bisphosphatase (PFKFB) is a family of bidirectional glycolytic enzymes possessing both kinase and phosphatase functions and has emerged as important oncogene in multiple types of cancer. However, its clinical relevance, functional significance, and underlying mechanistic insights in hepatocellular carcinoma (HCC), the primary malignancy that develops in the most important metabolic organ, has never been addressed. METHODS: PFKFB4 expression was examined by RNA sequencing in The Cancer Genome Atlas and our in-house HCC cohort. The up-regulation of PFKFB4 expression was confirmed further by quantitative polymerase chain reaction in an expanded hepatitis B virus-associated HCC cohort followed by clinicopathologic correlation analysis. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-mediated PFKFB4 knockout cells were generated for functional characterization in vivo, targeted metabolomic profiling, as well as RNA sequencing analysis to comprehensively examine the impact of PFKFB4 loss in HCC. RESULTS: PFKFB4 expression was up-regulated significantly in HCC and correlated positively with TP53 and TSC2 loss-of-function mutations. In silico transcriptome-based analysis further revealed PFKFB4 functions as a critical hypoxia-inducible gene. Clinically, PFKFB4 up-regulation was associated with more aggressive tumor behavior. Functionally, CRISPR/Cas9-mediated PFKFB4 knockout significantly impaired in vivo HCC development. Targeted metabolomic profiling revealed that PFKFB4 functions as a phosphatase in HCC and its ablation caused an accumulation of metabolites in downstream glycolysis and the pentose phosphate pathway. In addition, PFKFB4 loss induced hypoxia-responsive genes in glycolysis and reactive oxygen species detoxification. Conversely, ectopic PFKFB4 expression conferred sorafenib resistance. CONCLUSIONS: PFKFB4 up-regulation supports HCC development and shows therapeutic implications.

Using mouse liver cancer models based on somatic genome editing to predict immune checkpoint inhibitor responses.

BACKGROUND & AIMS: Tyrosine kinase inhibitors (TKIs) and immune checkpoint inhibitors (ICIs) are the only two classes of FDA-approved drugs for individuals with advanced hepatocellular carcinoma (HCC). While TKIs confer only modest survival benefits, ICIs have been associated with remarkable outcomes but only in the minority of patients who respond. Understanding the mechanisms that determine the efficacy of ICIs in HCC will help to stratify patients likely to respond to ICIs. This study aims to elucidate how genetic composition and specific oncogenic pathways regulate the immune composition of HCC, which directly affects response to ICIs. METHODS: A collection of mouse HCCs with genotypes that closely simulate the genetic composition found in human HCCs were established using genome-editing approaches involving the delivery of transposon and CRISPR-Cas9 systems by hydrodynamic tail vein injection. Mouse HCC tumors were analyzed by RNA-sequencing while tumor-infiltrating T cells were analyzed by flow cytometry and single-cell RNA-sequencing. RESULTS: Based on the CD8+ T cell-infiltration level, we characterized tumors with different genotypes into cold and hot tumors. Anti-PD-1 treatment had no effect in cold tumors but was greatly effective in hot tumors. As proof-of-concept, a cold tumor (Trp53KO/MYCOE) and a hot tumor (Keap1KO/MYCOE) were further characterized. Tumor-infiltrating CD8+ T cells from Keap1KO/MYCOE HCCs expressed higher levels of proinflammatory chemokines and exhibited enrichment of a progenitor exhausted CD8+ T-cell phenotype compared to those in Trp53KO/MYCOE HCCs. The TKI sorafenib sensitized Trp53KO/MYCOE HCCs to anti-PD-1 treatment. CONCLUSION: Single anti-PD-1 treatment appears to be effective in HCCs with genetic mutations driving hot tumors, while combined anti-PD-1 and sorafenib treatment may be more appropriate in HCCs with genetic mutations driving cold tumors. IMPACT AND IMPLICATIONS: Genetic alterations of different driver genes in mouse liver cancers are associated with tumor-infiltrating CD8+ T cells and anti-PD-1 response. Mouse HCCs with different genetic compositions can be grouped into hot and cold tumors based on the level of tumor-infiltrating CD8+ T cells. This study provides proof-of-concept evidence to show that hot tumors are responsive to anti-PD-1 treatment while cold tumors are more suitable for combined treatment with anti-PD-1 and sorafenib. Our study might help to guide the design of patient stratification systems for single or combined treatments involving anti-PD-1.

Polo-like kinase 4 inhibitor CFI-400945 suppresses liver cancer through cell cycle perturbation and eliciting antitumor immunity.

BACKGROUND AND AIMS: Prognosis of HCC remains poor due to lack of effective therapies. Immune checkpoint inhibitors (ICIs) have delayed response and are only effective in a subset of patients. Treatments that could effectively shrink the tumors within a short period of time are idealistic to be employed together with ICIs for durable tumor suppressive effects. HCC acquires increased tolerance to aneuploidy. The rapid division of HCC cells relies on centrosome duplication. In this study, we found that polo-like kinase 4 (PLK4), a centrosome duplication regulator, represents a therapeutic vulnerability in HCC. APPROACH AND RESULTS: An orally available PLK4 inhibitor, CFI-400945, potently suppressed proliferating HCC cells by perturbing centrosome duplication. CFI-400945 induced endoreplication without stopping DNA replication, causing severe aneuploidy, DNA damage, micronuclei formation, cytosolic DNA accumulation, and senescence. The cytosolic DNA accumulation elicited the DEAD box helicase 41-stimulator of interferon genes-interferon regulatory factor 3/7-NF-κß cytosolic DNA sensing pathway, thereby driving the transcription of senescence-associated secretory phenotypes, which recruit immune cells. CFI-400945 was evaluated in liver-specific p53/phosphatase and tensin homolog knockout mouse HCC models established by hydrodynamic tail vein injection. Tumor-infiltrated immune cells were analyzed. CFI-400945 significantly impeded HCC growth and increased infiltration of cluster of differentiation 4-positive (CD4 + ), CD8 + T cells, macrophages, and natural killer cells. Combination therapy of CFI-400945 with anti-programmed death-1 showed a tendency to improve HCC survival. CONCLUSIONS: We show that by targeting a centrosome regulator, PLK4, to activate the cytosolic DNA sensing-mediated immune response, CFI-400945 effectively restrained tumor progression through cell cycle inhibition and inducing antitumor immunity to achieve a durable suppressive effect even in late-stage mouse HCC.