E2F8 exerts cancer-promoting effects by transcriptionally activating RRM2 and E2F8 knockdown synergizes with WEE1 inhibition in suppressing lung adenocarcinoma.

Ribonucleotide reductase (RR) is a rate-limiting enzyme that facilitates DNA replication and repair by reducing nucleotide diphosphates (NDPs) to deoxyribonucleotide diphosphates (dNDPs) and is thereby crucial for cell proliferation and cancer development. The E2F family of transcription factors includes key regulators of gene expression involved in cell cycle control. In this study, E2F8 expression was significantly increased in most cancer tissues of lung adenocarcinoma (LUAD) patients and was correlated with the expression of RRM2 through database and clinical samples analysis. The protein expression of E2F8 and RRM2 were positively correlated with tumor-node-metastasis (TNM) pathological stage, and high expression of E2F8 and RRM2 predicted a low 5-year overall survival rate in LUAD patients. Overexpression and knockdown experiments showed that E2F8 was essential for LUAD cell proliferation, DNA synthesis, and cell cycle progression, which were RRM2-dependent. Reporter gene, ChIP-qPCR, and DNA pulldown-Western blot assays indicated that E2F8 activated the transcription of the RRM2 gene by directly binding with the RRM2 promoter in LUAD cells. Previous studies indicated that inhibition of WEE1 kinase can suppress the phosphorylation of CDK1/2 and promote the degradation of RRM2. We further showed here that the combination of E2F8 knockdown with MK-1775, an inhibitor of WEE1 being evaluated in clinical trials, synergistically suppressed proliferation and promoted apoptosis of LUAD cells in vitro and in vivo. Thus, this study reveals a novel role of E2F8 as a proto-oncogenic transcription activator by activating RRM2 expression in LUAD, and targeting both the transcription and degradation mechanisms of RRM2 could produce a synergistic inhibitory effect for LUAD treatment in addition to conventional inhibition of RR enzyme activity.

JMJD5 inhibits lung cancer progression by facilitating EGFR proteasomal degradation.

Aberrant activation of epidermal growth factor receptor (EGFR) signaling is closely related to the development of non-small cell lung cancer (NSCLC). However, targeted EGFR therapeutics such as tyrosine kinase inhibitors (TKIs) face the challenge of EGFR mutation-mediated resistance. Here, we showed that the reduced JmjC domain-containing 5 (JMJD5) expression is negatively associated with EGFR stability and NSCLC progression. Mechanically, JMJD5 cooperated with E3 ligase HUWE1 to destabilize EGFR and EGFR TKI-resistant mutants for proteasomal degradation, thereby inhibiting NSCLC growth and promoting TKI sensitivity. Furthermore, we identified that JMJD5 can be transported into recipient cells via extracellular vesicles, thereby inhibiting the growth of NSCLC. Together, our findings demonstrate the tumor-suppressive role of JMJD5 in NSCLC and suggest a putative therapeutic strategy for EGFR-related NSCLC by targeting JMJD5 to destabilize EGFR.

The thioredoxin system determines CHK1 inhibitor sensitivity via redox-mediated regulation of ribonucleotide reductase activity.

Checkpoint kinase 1 (CHK1) is critical for cell survival under replication stress (RS). CHK1 inhibitors (CHK1i's) in combination with chemotherapy have shown promising results in preclinical studies but minimal efficacy with substantial toxicity in clinical trials. To explore novel combinational strategies that can overcome these limitations, we performed an unbiased high-throughput screen in a non-small cell lung cancer (NSCLC) cell line and identified thioredoxin1 (Trx1), a major component of the mammalian antioxidant-system, as a novel determinant of CHK1i sensitivity. We established a role for redox recycling of RRM1, the larger subunit of ribonucleotide reductase (RNR), and a depletion of the deoxynucleotide pool in this Trx1-mediated CHK1i sensitivity. Further, the TrxR1 inhibitor auronafin, an anti-rheumatoid arthritis drug, shows a synergistic interaction with CHK1i via interruption of the deoxynucleotide pool. Together, these findings identify a new pharmacological combination to treat NSCLC that relies on a redox regulatory link between the Trx system and mammalian RNR activity.

Identification of Monobenzone as a Novel Potential Anti-Acute Myeloid Leukaemia Agent That Inhibits RNR and Suppresses Tumour Growth in Mouse Xenograft Model.

Acute myeloid leukaemia (AML) is one of the most common types of haematopoietic malignancy. Ribonucleotide reductase (RNR) is a key enzyme required for DNA synthesis and cell proliferation, and its small subunit RRM2 plays a key role for the enzymatic activity. We predicted monobenzone (MB) as a potential RRM2 target compound based on the crystal structure of RRM2. In vitro, MB inhibited recombinant RNR activity (IC50 = 0.25 µM). Microscale thermophoresis indicated that MB inhibited RNR activity by binding to RRM2. MB inhibited cell proliferation (MTT IC50 = 6-18 µM) and caused dose-dependent DNA synthesis inhibition, cell cycle arrest, and apoptosis in AML cells. The cell cycle arrest was reversed by the addition of deoxyribonucleoside triphosphates precursors, suggesting that RNR was the intracellular target of the compound. Moreover, MB overcame drug resistance to the common AML drugs cytarabine and doxorubicin, and treatment with the combination of MB and the Bcl-2 inhibitor ABT-737 exerted a synergistic inhibitory effect. Finally, the nude mice xenografts study indicated that MB administration produced a significant inhibitory effect on AML growth with relatively weak toxicity. Thus, we propose that MB has the potential as a novel anti-AML therapeutic agent in the future.

Preclinical validation and phase I trial of 4-hydroxysalicylanilide, targeting ribonucleotide reductase mediated dNTP synthesis in multiple myeloma.

BACKGROUND: Aberrant DNA repair pathways contribute to malignant transformation or disease progression and the acquisition of drug resistance in multiple myeloma (MM); therefore, these pathways could be therapeutically exploited. Ribonucleotide reductase (RNR) is the rate-limiting enzyme for the biosynthesis of deoxyribonucleotides (dNTPs), which are essential for DNA replication and DNA damage repair. In this study, we explored the efficacy of the novel RNR inhibitor, 4-hydroxysalicylanilide (HDS), in myeloma cells and xenograft model. In addition, we assessed the clinical activity and safety of HDS in patients with MM. METHODS: We applied bioinformatic, genetic, and pharmacological approaches to demonstrate that HDS was an RNR inhibitor that directly bound to RNR subunit M2 (RRM2). The activity of HDS alone or in synergy with standard treatments was evaluated in vitro and in vivo. We also initiated a phase I clinical trial of single-agent HDS in MM patients (ClinicalTrials.gov: NCT03670173) to assess safety and efficacy. RESULTS: HDS inhibited the activity of RNR by directly targeting RRM2. HDS decreased the RNR-mediated dNTP synthesis and concomitantly inhibited DNA damage repair, resulting in the accumulation of endogenous unrepaired DNA double-strand breaks (DSBs), thus inhibiting MM cell proliferation and inducing apoptosis. Moreover, HDS overcame the protective effects of IL-6, IGF-1 and bone marrow stromal cells (BMSCs) on MM cells. HDS prolonged survival in a MM xenograft model and induced synergistic anti-myeloma activity in combination with melphalan and bortezomib. HDS also showed a favorable safety profile and demonstrated clinical activity against MM. CONCLUSIONS: Our study provides a rationale for the clinical evaluation of HDS as an anti-myeloma agent, either alone or in combination with standard treatments for MM. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03670173, Registered 12 September 2018.

A rapid and environmentally friendly method for determination of parabens preservatives in flavors by supercritical fluid chromatography-tandem mass spectrometry.

A rapid method for determination of parabens preservatives (methyl paraben, ethyl paraben, isopropyl paraben, propyl paraben, isobutyl paraben, and butyl paraben) in flavors was established by using supercritical fluid chromatography-tandem mass spectrometry combined with dispersive solid-phase extraction. After adding methanol and primary secondary amine to the sample simultaneously, high extraction efficiency and good sample cleanup could be obtained by simple shaking. Parabens were well separated on a Chiralpak IG-3 column in 6 min by gradient elution. Recoveries from spiked blank samples at 0.5, 1.0, and 5.0 mg/kg were determined to be 88.3-106.6%with relative standard deviations less than 8.0%. All analytes achieved good linear relation (r ≥ 0.999 2). The limits of detection for all analytes ranged from 0.03 to 0.09 mg/kg and the limits of quantification from 0.11 to 0.31 mg/kg, respectively. A total of 20 actual samples were successfully analyzed by taking the proposed method. Being simple, rapid, green, and reliable, this method can be taken for the determination of parabens preservatives in flavors.

Super-enhancers and novel therapeutic targets in colorectal cancer.

Transcription factors, cofactors, chromatin regulators, and transcription apparatuses interact with transcriptional regulatory elements, including promoters, enhancers, and super-enhancers (SEs), to coordinately regulate the transcription of target genes and thereby control cell behaviors. Among these transcriptional regulatory components and related elements, SEs often play a central role in determining cell identity and tumor initiation and progression. Therefore, oncogenic SEs, which are generated within cancer cells in oncogenes and other genes important in tumor pathogenesis, have emerged as attractive targets for novel cancer therapeutic strategies in recent years. Herein, we review the identification, formation and activation modes, and regulatory mechanisms for downstream genes and pathways of oncogenic SEs. We also review the therapeutic strategies and compounds targeting oncogenic SEs in colorectal cancer and other malignancies.

Determination of Commonly Used Multiclass Pesticide Residues in Tobacco and Cigarette Smoke by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A novel method has been developed for the simultaneous determination of multiclass pesticide residues in tobacco and cigarette smoke, using a modified QuEChERS (quick, easy, cheap, effective, rugged and safe) procedure and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Cigarette mainstream smoke particulate was collected on a Cambridge filter pad. Pesticide residues was extracted with an aqueous solution, back extracted into acetonitrile after freezing, purified by dispersive solid phase extraction with primary-secondary amine adsorbents and analyzed by UPLC-MS/MS. The obtained mean recoveries of 16 pesticides commonly used on tobacco at three fortification levels (5.9, 94.1 and 352.9 ng g-1) ranged from 69.3 to 115.9% with relative standard deviations between 2.4 and 11.3%. The limits of detection ranged from 0.14 to 13.28 ng g-1. Finally, the proposed method was applied to study the pesticide smoke transfer ratio in 2 cigarettes with pesticide standard spiked and 51 cigarettes with one or more pesticide residues. The transfer ratio of pesticides residue in tobacco into the smoke might be much less than that from artificially spiked tobacco (<25%) with spiking levels varied from 1.88 to 9.41 µg g-1. The transfer ratio of pesticide from artificially spiked tobacco into cigarette mainstream smoke was from 0.0 to 56.5%, and pesticide residues from tobacco into cigarette smoke were from 0.0 to 26.1% using the ISO smoking method (ISO 3308 2012).

Highly sensitive time-resolved fluoroimmunoassay for the quantitative onsite detection of Alternaria longipes in tobacco.

AIMS: Alternaria longipes is a causal agent of brown spot of tobacco, which remains a serious threat to tobacco production. Herein, we established a detection method for A. longipes in tobacco samples based on the principle of time-resolved fluoroimmunoassay, in order to fulfil the requirement of rapid, sensitive and accurate detection in situ. METHODS AND RESULTS: A monoclonal antibody against A. longipes was generated, and its purity and titration were assessed using western blot and ELISA. The size of europium (III) nanospheres was measured to confirm successful antibody conjugation. The method described here can detect A. longipes protein lysates as low as 0.78 ng ml-1 , with recovery rates ranging from 85.96% to 99.67% in spiked tobacco. The specificity was also confirmed using a panel of microorganisms. CONCLUSIONS: The fluorescent strips allow rapid and sensitive onsite detection of A. longipes in tobacco samples, with high accuracy, specificity, and repeatability. SIGNIFICANCE AND IMPACT OF THE STUDY: This novel detection method provides convenience of using crude samples without complex procedures, and therefore allows rapid onsite detection by end users and quick responses towards A. longipes, which is critical for disease control and elimination of phytopathogens.

miR-377-3p-Mediated EGR1 Downregulation Promotes B[a]P-Induced Lung Tumorigenesis by Wnt/Beta-Catenin Transduction.

Polycyclic aromatic hydrocarbons (PAHs), particularly benzo[a]pyrene (B[a]P), found in cigarette smoke and air pollution, is an important carcinogen. Nevertheless, early molecular events and related regulatory effects of B[a]P-mediated cell transformation and tumor initiation remain unclear. This study found that EGR1 was significantly downregulated during human bronchial epithelial cell transformation and mice lung carcinogenesis upon exposure to B[a]P and its active form BPDE, respectively. In contrast, overexpression of EGR1 inhibited the BPDE-induced cell malignant transformation. Moreover, miR-377-3p was strongly enhanced by BPDE/B[a]P exposure and crucial for the inhibition of EGR1 expression by targeting the 3'UTR of EGR1. MiR-377-3p antagomir reversed the effect of EGR1 downregulation in cell malignant transformation and tumor initiation models. Furthermore, the B[a]P-induced molecular changes were evaluated by IHC in clinical lung cancer tissues and examined with a clinic database. Mechanistically, EGR1 inhibition was also involved in the regulation of Wnt/ß-catenin transduction, promoting lung tumorigenesis following B[a]P/BPDE exposure. Taken together, the results demonstrated that bBenzo[a]pyrene exposure might induce lung tumorigenesis through miR-377-3p-mediated reduction of EGR1 expression, suggesting an important role of EGR1 in PAHs-induced lung carcinogenesis.

A MYBL2 complex for RRM2 transactivation and the synthetic effect of MYBL2 knockdown with WEE1 inhibition against colorectal cancer.

Ribonucleotide reductase (RR) is a unique enzyme for the reduction of NDPs to dNDPs, the building blocks for DNA synthesis and thus essential for cell proliferation. Pan-cancer profiling studies showed that RRM2, the small subunit M2 of RR, is abnormally overexpressed in multiple types of cancers; however, the underlying regulatory mechanisms in cancers are still unclear. In this study, through searching in cancer-omics databases and immunohistochemistry validation with clinical samples, we showed that the expression of MYBL2, a key oncogenic transcriptional factor, was significantly upregulated correlatively with RRM2 in colorectal cancer (CRC). Ectopic expression and knockdown experiments indicated that MYBL2 was essential for CRC cell proliferation, DNA synthesis, and cell cycle progression in an RRM2-dependent manner. Mechanistically, MYBL2 directly bound to the promoter of RRM2 gene and promoted its transcription during S-phase together with TAF15 and MuvB components. Notably, knockdown of MYBL2 sensitized CRC cells to treatment with MK-1775, a clinical trial drug for inhibition of WEE1, which is involved in a degradation pathway of RRM2. Finally, mouse xenograft experiments showed that the combined suppression of MYBL2 and WEE1 synergistically inhibited CRC growth with a low systemic toxicity in vivo. Therefore, we propose a new regulatory mechanism for RRM2 transcription for CRC proliferation, in which MYBL2 functions by constituting a dynamic S-phase transcription complex following the G1/early S-phase E2Fs complex. Doubly targeting the transcription and degradation machines of RRM2 could produce a synthetic inhibitory effect on RRM2 level with a novel potential for CRC treatment.

Pterostilbene inhibits hepatocellular carcinoma proliferation and HBV replication by targeting ribonucleotide reductase M2 protein.

Hepatocellular carcinoma (HCC), one of the most deadly diseases all around the world. HBV infection is a causative factor of HCC and closely associated with HCC development. Ribonucleotide reductase (RR) is a key enzyme for cellular DNA synthesis and RR small subunit M2 (RRM2) is highly upregulated in HCC with poor survival rates. We have previously shown that HBV can activate the expression of RRM2 and the activity of RR enzyme for the viral DNA replication in host liver cells. Thus, RRM2 may be an important therapeutic target for HCC and HBV-related HCC. Pterostilbene, a natural plant component, potently inhibited in vitro RR enzyme activity with the IC50 of about 0.62 µM through interacting with RRM2 protein, which was much higher than current RRM2 inhibitory drugs. Pterostilbine inhibited cell proliferation with an MTT IC50 of about 20-40 µM in various HCC cell lines, causing DNA synthesis inhibition, cell cycle arrest at S phase, and accordingly apoptosis. On the other hand, the compound significantly inhibited HBV DNA replication in HBV genome integrated and newly transfected HCC cells, and the EC50 for inhibiting HBV replication was significantly lower than the IC50 for inhibiting HCC proliferation. Notably, pterostilbene possessed a similar inhibitory activity in sorafenib and lamivudine resistant HCC cells. Moreover, the inhibitory effects of pterostilbine against HCC proliferation and HBV replication were significantly reversed by addition of dNTP precursors, suggesting that RR was the intracellular target of the compound. Finally, pterostilbine effectively inhibited HCC xenograft growth with a relatively low toxicity in nude mouse experiments. This study demonstrates that pterostilbene is a novel potent RR inhibitor by targeting RRM2. It can simultaneously inhibit HCC proliferation and HBV replication with a potential new use for treatment of HCC and HBV-related HCC.

Age-related changes in metabolites in young donor livers and old recipient sera after liver transplantation from young to old rats.

Liver ageing not only damages liver function but also harms systemic metabolism. To better understand the mechanisms underlying liver ageing, we transplanted the livers of young rats to young and old rats and performed untargeted metabolomics to detect changes in the metabolites in the liver tissues and sera. A total of 153 metabolites in the livers and 83 metabolites in the sera were different between the old and young rats that did not undergo liver transplantation; among these metabolites, 7 different metabolites were observed in both the livers and sera. Five weeks after liver transplantation, the levels of 25 metabolites in the young donor livers were similar to those in the old rats, and this result probably occurred due to the effect of the whole-body environment of the older recipients on the young livers. The 25 altered metabolites included organic acids and derivatives, lipids and lipid-like molecules, etc. In the sera, the differences in 78 metabolites, which were significant between the young and old rats, were insignificant in the old recipient rats and made the metabolic profile of the old recipients more similar to that of the young recipients. Finally, combining the above metabolomic data with the transcriptomic data from the GEO, we found that the altered metabolites and genes in the liver were enriched in 9 metabolic pathways, including glycerophospholipid, arachidonic acid, histidine and linoleate. Thus, this study revealed important age-related metabolites and potential pathways as well as the interaction between the liver and the whole-body environment.

A rapid method for the simultaneous stereoselective determination of the triazole fungicides in tobacco by supercritical fluid chromatography-tandem mass spectrometry combined with pass-through cleanup.

This work presents a simple, rapid and green chiral analysis method for five triazole fungicides (penconazole, tebuconazole, triadimefon, myclobutanil, and triadimenol) in tobacco, by which the samples were cleaned up by the novel pass-through solid phase extraction and subsequently the stereoisomers were separated and determined by the supercritical fluid chromatography-tandem mass spectrometry (SFC-MS/MS). Optimized separation of the stereoisomers was achieved on an ACQUITY UPC2 Trefoil AMY 1 column within 6 min. Under fortified concentration levels of 0.1, 0.5 and 2.0 mg/kg, the mean recoveries were 82.8-106.6%, the intra-day relative standard deviations (RSDs) were 1.1-6.6%, and the inter-day RSDs were 2.5-5.6%. The correlation coefficient was greater than 0.9926 for all studied analytes within the range of 10-500 ng/mL. The limits of detection (LODs) for all stereoisomers ranged from 0.26 µg/kg to 3.24 µg/kg. The established method was subsequently successfully applied to analyze authentic samples, confirming that this method is a novel, rapid and environmentally friendly method for the stereoselective separation of triazole fungicides in tobacco.

Osalmid, a Novel Identified RRM2 Inhibitor, Enhances Radiosensitivity of Esophageal Cancer.

PURPOSE: Esophageal cancer (EC) is an aggressive malignancy and is often resistant to currently available therapies. Inhibition of ribonucleotide reductase small subunit M2 (RRM2) in tumors is speculated to mediate chemosensitization. Previous studies have reported that Osalmid could act as an RRM2 inhibitor. We explored whether RRM2 was involved in radioresistance and the antitumor effects of Osalmid in EC. METHODS AND MATERIALS: RRM2 expression was detected by immunohistochemistry in EC tissues. The effects of Osalmid on cell proliferation, apoptosis, and cell cycle were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphhenyl tetrazolium, colony formation, and flow cytometry assays. DNA damage, cell apoptosis, and senescence induced by Osalmid or ionizing radiation (IR) alone, or both, were detected with immunofluorescence, flow cytometry, Western blot, and ß-galactosidase staining. A xenograft mouse model of EC was used to investigate the potential synergistic effects of Osalmid and IR in vivo. RESULTS: The expression of RRM2 in treatment-resistant EC tissues is much higher than in treatment-sensitive EC, and strong staining of RRM2 was correlated with shorter overall survival. We observed direct cytotoxicity of Osalmid in EC cells. Osalmid also produced inhibition of the ERK1/2 signal transduction pathway and substantially enhanced IR-induced DNA damage, apoptosis, and senescence. Furthermore, treatment with Osalmid and IR significantly suppressed tumor growth in xenograft EC models without additional toxicity to the hematologic system and internal organs. CONCLUSIONS: Our study revealed that RRM2 played a vital role in radioresistance in EC, and Osalmid synergized with IR to exert its antitumor effects both in vitro and in vivo.

[Construction, expression and purification of a mammalian secretory recombinant fusion protein rPC].

Drugs targeting immune checkpoint are used for cancer treatment, but resistance to single drug may occur. Combination therapy blocking multiple checkpoints simultaneously can improve clinical outcome. Therefore, we designed a recombinant protein rPC to block multiple targets, which consists of extracellular domains of programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). The coding sequence was inserted into expression vector and stably transfected into HEK293 cells. The culture supernatant was collected and rPC was affinity-purified. Real-time quantitative PCR was used to evaluate the expression levels of ligands for PD-1 and CTLA-4 in several human cancer cell lines. The binding of rPC with cancer cells was examined by immunofluorescence cell staining, the influence of rPC on cancer cell growth was assayed by CCK-8. The results showed that rPC could be expressed and secreted by stably transfected HEK293 cells, the purified rPC could bind to lung cancer NCI-H226 cells which have high levels of ligands for PD-1 and CTLA-4, no direct impact on cancer cell growth could be observed by rPC treatment. The recombinant protein rPC can be functionally assayed further for developing novel immunotherapeutic drugs for cancer.

STAT3 activates MSK1-mediated histone H3 phosphorylation to promote NFAT signaling in gastric carcinogenesis.

Epigenetic abnormalities contribute significantly to the development and progression of gastric cancer. However, the underlying regulatory networks from oncogenic signaling pathway to epigenetic dysregulation remain largely unclear. Here we showed that STAT3 signaling, one of the critical links between inflammation and cancer, acted as a control pathway in gastric carcinogenesis. STAT3 aberrantly transactivates the epigenetic kinase mitogen- and stress-activated protein kinase 1 (MSK1), thereby phosphorylating histone H3 serine10 (H3S10) and STAT3 itself during carcinogen-induced gastric tumorigenesis. We further identified the calcium pathway transcription factor NFATc2 as a novel downstream target of the STAT3-MSK1 positive-regulating loop. STAT3 forms a functional complex with MSK1 at the promoter of NFATc2 to promote its transcription in a H3S10 phosphorylation-dependent way, thus affecting NFATc2-related inflammatory pathways in gastric carcinogenesis. Inhibiting the STAT3/MSK1/NFATc2 signaling axis significantly suppressed gastric cancer cell proliferation and xenograft tumor growth, which provides a potential novel approach for gastric carcinogenesis intervention by regulating aberrant epigenetic and transcriptional mechanisms.

Integrative Analysis Reveals Across-Cancer Expression Patterns and Clinical Relevance of Ribonucleotide Reductase in Human Cancers.

Mining cancer-omics databases deepens our understanding of cancer biology and can lead to potential breakthroughs in cancer treatment. Here, we propose an integrative analytical approach to reveal across-cancer expression patterns and identify potential clinical impacts for genes of interest from five representative public databases. Using ribonucleotide reductase (RR), a key enzyme in DNA synthesis and cancer-therapeutic targeting, as an example, we characterized the mRNA expression profiles and inter-component associations of three RR subunit genes and assess their differing pathological and prognostic significance across over 30-types of cancers and their related subtypes. Findings were validated by immunohistochemistry with clinical tissue samples (n = 211) collected from multiple cancer centers in China and with clinical follow-up. Underlying mechanisms were further explored and discussed using co-expression gene network analyses. This framework represents a simple, efficient, accurate, and comprehensive approach for cancer-omics resource analysis and underlines the necessity to separate the tumors by their histological or pathological subtypes during the clinical evaluation of molecular biomarkers.

The inflammatory cytokine IL-6 induces FRA1 deacetylation promoting colorectal cancer stem-like properties.

Colorectal cancer (CRC) has long been known for its tight association with chronic inflammation, thought to play a key role in tumor onset and malignant progression through the modulation of cancer stemness. However, the underlying molecular and cellular mechanisms are still largely elusive. Here we show that the IL-6/STAT3 inflammatory signaling axis induces the deacetylation of FRA1 at the Lys-116 residue located within its DNA-binding domain. The HDAC6 deacetylase underlies this key modification leading to the increase of FRA1 transcriptional activity, the subsequent transactivation of NANOG expression, and the acquisition of stem-like cellular features. As validated in a large (n = 123) CRC cohort, IL-6 secretion was invariably accompanied by increased FRA1 deacetylation at K116 and an overall increase in its protein levels, coincident with malignant progression and poor prognosis. Of note, combined treatment with the conventional cytotoxic drug 5-FU together with Tubastatin A, a HDAC6-specific inhibitor, resulted in a significant in vivo synergistic inhibitory effect on tumor growth through suppression of CRC stemness. Our results reveal a novel transcriptional and posttranslational regulatory cross-talk between inflammation and stemness signaling pathways that underlie self-renewal and maintenance of CRC stem cells and promote their malignant behavior. Combinatorial treatment aimed at the core regulatory mechanisms downstream of IL-6 may offer a novel promising approach for CRC treatment.