Small molecular modulators of JMJD1C preferentially inhibit growth of leukemia cells.

Histone demethylases are promising therapeutic targets as they play fundamental roles for survival of Mixed lineage leukemia rearranged acute leukemia (MLLr AL). Here we focused on the catalytic Jumonji domain of histone H3 lysine 9 (H3K9) demethylase JMJD1C to screen for potential small molecular modulators from 149,519 natural products and 33,765 Chinese medicine components via virtual screening. JMJD1C Jumonji domain inhibitor 4 (JDI-4) and JDI-12 that share a common structural backbone were detected within the top 15 compounds. Surface plasmon resonance analysis showed that JDI-4 and JDI-12 bind to JMJD1C and its family homolog KDM3B with modest affinity. In vitro demethylation assays showed that JDI-4 can reverse the H3K9 demethylation conferred by KDM3B. In vivo demethylation assays indicated that JDI-4 and JDI-12 could induce the global increase of H3K9 methylation. Cell proliferation and colony formation assays documented that JDI-4 and JDI-12 kill MLLr AL and other malignant hematopoietic cells, but not leukemia cells resistant to JMJD1C depletion or cord blood cells. Furthermore, JDI-16, among multiple compounds structurally akin to JDI-4/JDI-12, exhibits superior killing activities against malignant hematopoietic cells compared to JDI-4/JDI-12. Mechanistically, JDI-16 not only induces apoptosis but also differentiation of MLLr AL cells. RNA sequencing and quantitative PCR showed that JDI-16 induced gene expression associated with cell metabolism; targeted metabolomics revealed that JDI-16 downregulates lactic acids, NADP+ and other metabolites. Moreover, JDI-16 collaborates with all-trans retinoic acid to repress MLLr AML cells. In summary, we identified bona fide JMJD1C inhibitors that induce preferential death of MLLr AL cells.

A protein fragment derived from DNA-topoisomerase I as a novel tumour-associated antigen for the detection of early stage carcinoma.

BACKGROUND: The production of autoantibodies against tumour-associated antigens (TAAs) is believed to reflect greater immunologic reactivity in cancer patients and enhanced immune surveillance for cancer cells. Over the past few decades, a number of different TAAs and their corresponding autoantibodies have been investigated. However, positive frequency of autoantibody detection in cancer patients has been relatively low. Here we describe a novel TAA that was a fragment derived from human DNA-topoiomerase I and an autoantibody against the novel TAA with relatively high positive frequency in the sera of early-stage non-small-cell lung cancer (NSCLC), gastric cancer (GC), colorectal cancer (CRC) and oesophageal squamous cell carcinoma (ESCC). METHODS: Serologic enzyme-linked immunosorbent assay (ELISA) and western blot were used to discover a novel TAA with a molecular weight of 48 kDa separated by ion exchange chromatography. Autoantibody ELISA, immnohistochemistry and immunofluorescent staining, recombinant protein cloning/expression and western blot were used to identify the novel TAA. The association of the autoantibody against the novel TAA with early-stage carcinoma was explored by screening 203 stage I/II patients and 170 stage III/IV patients with NSCLC, GC, CRC or ESCC. RESULTS: We identified the novel TAA as a fragment derived from human DNA-topoiomerase I (TOP1). We found that the novel TAA induced specific autoantibodies with a high prevalence that ranged from 58 to 72% in some of the most common types of cancer. We observed that the immune response against the novel TAA was associated with early stage ESCC, GC, CRC and NSCLC. CONCLUSIONS: The findings in this study suggest that the autoantibody against the novel TAA may be a potential biomarker for use in the early detection and diagnosis of cancer.

Runx1 regulation of Pu.1 corepressor/coactivator exchange identifies specific molecular targets for leukemia differentiation therapy.

Gene activation requires cooperative assembly of multiprotein transcription factor-coregulator complexes. Disruption to cooperative assemblage could underlie repression of tumor suppressor genes in leukemia cells. Mechanisms of cooperation and its disruption were therefore examined for PU.1 and RUNX1, transcription factors that cooperate to activate hematopoietic differentiation genes. PU.1 is highly expressed in leukemia cells, whereas RUNX1 is frequently inactivated by mutation or translocation. Thus, coregulator interactions of Pu.1 were examined by immunoprecipitation coupled with tandem mass spectrometry/Western blot in wild-type and Runx1-deficient hematopoietic cells. In wild-type cells, the NuAT and Baf families of coactivators coimmunoprecipitated with Pu.1. Runx1 deficiency produced a striking switch to Pu.1 interaction with the Dnmt1, Sin3A, Nurd, CoRest, and B-Wich corepressor families. Corepressors of the Polycomb family, which are frequently inactivated by mutation or deletion in myeloid leukemia, did not interact with Pu.1. The most significant gene ontology association of Runx1-Pu.1 co-bound genes was with macrophages, therefore, functional consequences of altered corepressor/coactivator exchange were examined at Mcsfr, a key macrophage differentiation gene. In chromatin immunoprecipitation analyses, high level Pu.1 binding to the Mcsfr promoter was not decreased by Runx1 deficiency. However, the Pu.1-driven shift from histone repression to activation marks at this locus, and terminal macrophage differentiation, were substantially diminished. DNMT1 inhibition, but not Polycomb inhibition, in RUNX1-translocated leukemia cells induced terminal differentiation. Thus, RUNX1 and PU.1 cooperate to exchange corepressors for coactivators, and the specific corepressors recruited to PU.1 as a consequence of RUNX1 deficiency could be rational targets for leukemia differentiation therapy.

Differentiation of Acute Leukemia Cells Including Cells with MLL-AF4 Rearrangements Induced by Jiyuan Oridonin A.

BACKGROUND: Chromosomal rearrangements involving the Mixed lineage leukemia (MLL) gene are observed in acute leukemia (AL) patients, which have poor prognosis, especially in infants. Hence, there is still a challenge to develop other effective agents to treat AL with MLL rearrangements (MLLr). MLL has been shown to rearrange with partner genes, of which the most frequently observed are AF4 and AF9. Moreover, AL is characterized by a differentiation blockage resulting in the accumulation of immature cells. An ent-kaurene diterpenoid compound, Jiyuan Oridonin A (JOA), has been shown to reduce the viability of AML cells by differentiation. METHODS: We aimed to evaluate the effect of JOA on the growth and differentiation of AL cells (SEM, JURKAT and MV4-11) including cells with MLLr-AF4 by cell proliferation assay, colony formation assay, cell cycle analysis, cell apoptosis analysis, measurement of cell surface antigens, cell morphology, mRNA-sequencing analysis, quantitative Real-time PCR and Western blotting analysis. RESULTS: Our findings demonstrated that the proliferation of AL cells including cells with MLLr-AF4 was significantly suppressed by JOA, which induced cell differentiation followed by G0/G1 cell cycle withdrawal. Moreover, JOA-mediated cell differentiation was likely due to activation of G-CSFR in MV4-11 cells. CONCLUSION: Our results suggest that JOA may be considered a promising anti-leukemia compound to develop to surmount the differentiation block in AL patients.

Dihydroartemisinin induces ferroptosis in T cell acute lymphoblastic leukemia cells by downregulating SLC7A11 and activating the ATF4­CHOP signaling pathway.

The present study aimed to investigate the anti-leukemic effects of dihydroartemisinin (DHA) on T-cell acute lymphoblastic leukemia (T-ALL) cell lines, Jurkat and Molt-4, and the underlying mechanisms. Cell Counting Kit-8 was performed to measure cell viability. Cell apoptosis and cell cycle distribution were assessed by flow cytometry. The expression levels of ATF4 and CHOP mRNA were assessed by reverse transcription-quantitative PCR, while the protein abundance of SLC7A11, GPX4, ATF4 and CHOP was determined by western blotting. Moreover, malondialdehyde, glutathione (GSH) and reactive oxygen species (ROS) assays were used to detect the levels of ferroptosis. The results showed that DHA suppressed T-ALL cell viability in vitro, and induced cell cycle arrest at S or G2/M phase. DHA also induced ROS burst, activated endoplasmic reticulum (ER) stress, disrupted the system Xc--GSH-GSH peroxidase 4 antioxidant system, and increased lipid peroxide accumulation, resulting in cell death. By contrast, the pharmacological inhibition of ferroptosis alleviated DHA-induced cell death, confirming that DHA induces T-ALL cell death via ferroptosis. Mechanistically, the effect of DHA on ferroptosis was partly mediated by downregulating SLC7A11 and upregulating the ATF4-CHOP signaling pathway, which is associated with ER stress. These results indicated that DHA may induce ferroptosis in T-ALL cell lines and could represent a promising therapeutic agent for treating T-ALL.

RUNX1 regulates corepressor interactions of PU.1.

The transcription factor (TF) RUNX1 cooperates with lineage-specifying TFs (eg, PU.1/SPI1) to activate myeloid differentiation genes, such as macrophage and granulocyte macrophage colony-stimulating factor receptors (MCSFR and GMCSFR). Disruption of cooperative gene activation could contribute to aberrant repression of differentiation genes and leukemogenesis initiated by mutations and translocations of RUNX1. To investigate the mechanisms underlying cooperative gene activation, the effects of Runx1 deficiency were examined in an in vitro model of Pu.1-driven macrophage differentiation and in primary cells. Runx1 deficiency decreased Pu.1-mediated activation of Mcsfr and Gmcsfr, accompanied by decreased histone acetylation at the Mcsfr and Gmcsfr promoters, and increased endogenous corepressor (Eto2, Sin3A, and Hdac2) coimmunoprecipitation with Pu.1. In cotransfection experiments, corepressors were excluded from a multiprotein complex containing full-length RUNX1 and PU.1. However, corepressors interacted with PU.1 if wild-type RUNX1 was replaced with truncated variants associated with leukemia. Histone deacetylase (HDAC) enzyme activity is a major component of corepressor function. HDAC inhibition using suberoylanilide hydroxamic acid or MS-275 significantly increased MCSFR and GMCSFR expression in leukemia cell lines that express PU.1 and mutated or translocated RUNX1. RUNX1 deficiency is associated with persistent corepressor interaction with PU.1. Thus, inhibiting HDAC can partly compensate for the functional consequences of RUNX1 deficiency.

Histone lysine demethylase 3B regulates autophagy via transcriptional regulation of GABARAPL1 in acute myeloid leukemia cells.

Macroautophagy (hereafter referred to as autophagy) is a highly conserved self­digestion process that is critical for maintaining homeostasis in response to various stresses. The autophagy­related protein family, including the GABA type A receptor­associated protein (GABARAP) and microtubule­associated protein 1 light chain 3 subfamilies, is crucial for autophagosome biogenesis. Although the regulatory machinery of autophagy in the cytoplasm has been widely studied, its transcriptional and epigenetic regulatory mechanisms still require more targeted investigations. The present study identified histone lysine demethylase 3B (KDM3B) as a crucial component of autophagy on a panel of leukemia cell lines, including K562, THP1 and U937, resulting in transcriptional activation of the autophagy­related gene GABA type A receptor­associated protein like 1 (GABARAPL1). KDM3B expression promoted autophagosome formation and affected the autophagic flux in leukemia cells under the induction of external stimuli. Notably, RNA­sequencing and reverse transcription­quantitative PCR analysis showed that KDM3B knockout inhibited the expression of GABARAPL1. Chromatin immunoprecipitation­quantitative PCR and luciferase assay showed that KDM3B was associated with the GABARAPL1 gene promoter under stimulation and enhanced its transcription. The present findings demonstrated that KDM3B was critical for regulating the GABARAPL1 gene and influencing the process of autophagy in leukemia cells. These results provide a new insight for exploring the association between autophagy and KDM3B epigenetic regulation in leukemia.

FOXK2 regulates PFKFB3 in promoting glycolysis and tumorigenesis in multiple myeloma.

Forkhead box K2 (FOXK2) is a transcription factor involved in regulating the pathophysiological processes in many types of cancers. Functioning as either an oncogene or tumor suppressor, FOXK2 is involved in cell proliferation, metastasis, DNA damage, metabolism, and autophagy. However, the functions of FOXK2 in multiple myeloma (MM) are still unexplored. Here we show that FOXK2 silencing by small interfering RNA (siRNA) prevented the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) via dephosphorylation of an AMP-activated protein kinase (AMPK). Consistently, suppression of FOXK2 inhibited glycolysis and cell proliferation in MM cells. Furthermore, the correlation between FOXK2 expression and disease progression in MM was evaluated using the TCGA (The Cancer Genome Atlas) database. Taken together, we identified a novel FOXK2-dependent signaling pathway involved in the regulation of PFKFB3 expression in response to glycolysis, which might serve as a potential therapeutic target in MM.

Differentiation of imatinib -resistant chronic myeloid leukemia cells with BCR-ABL-T315I mutation induced by Jiyuan Oridonin A.

Chronic myeloid leukemia (CML) results from BCR-ABL oncogene, which blocks CML cells differentiation and protects these cells from apoptosis. T315I mutated BCR-ABL is the main cause of the resistance mediated by imatinib and second generation BCR-ABL inhibitor. CML with the T315I mutation has been considered to have poor prognosis. Here, we determined the effect of Jiyuan oridonin A (JOA), an ent-kaurene diterpenoid compound, on the differentiation blockade in imatinib-sensitive, particularly, imatinib-resistant CML cells with BCR-ABL-T315I mutation by cell proliferation assay, apoptosis analysis, cell differentiation analysis, cell cycle analysis and colony formation assay. We also investigated the possible molecular mechanism by mRNA sequencing, qRT-PCR and Western blotting. We found that JOA at lower concentration significantly inhibited the proliferation of CML cells expressing mutant BCR-ABL (T315I mutation included) and wild-type BCR-ABL, which was due to that JOA induced the cell differentiation and the cell cycle arrest at G0/G1 phase. Interestingly, JOA possessed stronger anti-leukemia activity than its analogues such as OGP46 and Oridonin, which has been investigated extensively. Mechanistically, the cell differentiation mediated by JOA may be originated from the inhibition of BCR-ABL/c-MYC signaling in CML cells expressing wild-type BCR-ABL and BCR-ABL-T315I. JOA displayed the activity of inhibiting the BCR-ABL and promoted differentiation of not only imatinib -sensitive but also imatinib -resistant cells with BCR-ABL mutation, which could become a potent lead compound to overcome the imatinib -resistant induced by inhibitors of BCR-ABL tyrosine kinase in CML therapy.

Epigenetic regulation by decitabine of melanoma differentiation in vitro and in vivo.

Apoptosis genes, such as TP53 and p16/CDKN2A, that mediate responses to cytotoxic chemotherapy, are frequently nonfunctional in melanoma. Differentiation may be an alternative to apoptosis for inducing melanoma cell cycle exit. Epigenetic mechanisms regulate differentiation, and DNA methylation alterations are associated with the abnormal differentiation of melanoma cells. The effects of the deoxycytidine analogue decitabine (5-aza-2'-deoxycytidine), which depletes DNA methyl transferase 1 (DNMT1), on melanoma differentiation were examined. Treatment of human and murine melanoma cells in vitro with concentrations of decitabine that did not cause apoptosis inhibited proliferation accompanied by cellular differentiation. A decrease in promoter methylation, and increase in expression of the melanocyte late-differentiation driver SOX9, was followed by increases in cyclin-dependent kinase inhibitors (CDKN) p27/CDKN1B and p21/CDKN1A that mediate cell cycle exit with differentiation. Effects were independent of the TP53, p16/CDKN2A and also the BRAF status of the melanoma cells. Resistance, when observed, was pharmacologic, characterized by diminished ability of decitabine to deplete DNMT1. Treatment of murine melanoma models in vivo with intermittent, low-dose decitabine, administered sub-cutaneously to limit high peak drug levels that cause cytotoxicity and increase exposure time for DNMT1 depletion, and with tetrahydrouridine to decrease decitabine metabolism and further increase exposure time, inhibited tumor growth and increased molecular and tumor stromal factors implicated in melanocyte differentiation. Modification of decitabine dose, schedule and formulation for differentiation rather than cytotoxic objectives inhibits the growth of melanoma cells in vitro and in vivo.

FOXK2 transcription factor and its roles in tumorigenesis (Review).

Forkhead box K2 (FOXK2) is a central transcriptional regulator of embryonic development and cell homeostasis. Since its discovery, evidence has shown that FOXK2 mediates a variety of biological processes involving in genomic stability, DNA repair, cancer stem cell maintenance, cell proliferation, apoptosis and cell metabolism. The inherent structural characteristics of FOXK2 enable it as a transcriptional factor (TF) to cooperate with other active molecules in cancer development. FOXK2 mediates several significant chromatin events that are necessary for some chromatin accessibility and protein-protein interaction. FOXK2 is involved in the pathogenesis of a number of types of cancer as an oncoprotein or tumor suppressor depending on its interactive partners. Therefore, the loss of FOXK2 and its functions directly or indirectly affect the fate of cells. FOXK2 expresses differentially in a number of types of cancer and is involved in a number of aspects of carcinogenesis. However, its roles in tumorigenesis remain largely unexplored. The present review focused on the latest findings and evidence on the broad roles and possible mediating mechanisms of FOXK2 in carcinogenesis. The recent findings about FOXK2 may shed light on the direction of future FOXK2 research in tumorigenesis.

The Histone Deacetylase Inhibitor I1 Induces Differentiation of Acute Leukemia Cells With MLL Gene Rearrangements via Epigenetic Modification.

Acute leukemia (AL) is characterized by excessive proliferation and impaired differentiation of leukemic cells. AL includes acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Previous studies have demonstrated that about 10% of AML and 22% of ALL are mixed lineage leukemia gene rearrangements (MLLr) leukemia. The prognosis of MLLr leukemia is poor and new therapeutics are urgently needed. Differentiation therapy with all-trans-retinoic acid (ATRA) has prolonged the 5-years disease-free survival rate in acute promyelocytic leukemia (APL), a subtype of AML. However, the differentiation therapy has not been effective in other acute leukemia. Here, we aim to explore the cell differentiation effect of the potent HDACs inhibitor, I1, and the possible mechanism on the MLLr-AML and MLLr-ALL cells (MOLM-13, THP-1, MV4-11 and SEM). It is shown that I1 can significantly inhibit the proliferation and the colony-forming ability of MOLM-13, THP-1, MV4-11 and SEM cells by promoting cell differentiation coupled with cell cycle block at G0/G1 phase. We show that the anti-proliferative effect of I1 attributed to cell differentiation is most likely associated with the HDAC inhibition activity, as assessed by the acetylation of histone H3 and H4, which may dictates the activation of hematopoietic cell lineage pathway in both MOLM-13 and THP-1 cell lines. Moreover, the activity of HDAC inhibition of I1 is stronger than that of SAHA in MOLM-13 and THP-1 cells. Our findings suggest that I1, as a chromatin-remodeling agent, could be a potent epigenetic drug to overcome differentiation block in MLLr-AL patients and would be promising for the treatment of AL.

JMJD1C-regulated lipid synthesis contributes to the maintenance of MLL-rearranged acute myeloid leukemia.

Mixed Lineage Leukemia rearranged acute myeloid leukemia (MLLr AML) predicts a poor prognosis. Histone demethylase JMJD1C is a potential druggable target of MLLr AML. However, little is known about how JMJD1C contributes to MLLr AML. Here we found that JMJD1C regulates lipid synthesis-associated genes including FADS2, SCD in MLLr AML cells. Lipid synthesis-associated protein FABP5 was identified as a specific interacting protein of JMJD1C and binds to the jumonji domain of JMJD1C. FABP5 also regulates JMJD1C mRNA and protein expression. JDI-10, a small molecular inhibitor of JMJD1C identified by us, represses MLLr AML cells, induces apoptosis, and decreases JMJD1C-regulated lipid synthesis genes. Moreover, JDI-10 mediated suppression of MLLr AML cells can be rescued by palmitic acid, oleic acid, or recombinant FABP5. In summary, we identified that JMJD1C-regulated lipid synthesis contributes to the maintenance of MLLr AML. Lipid synthesis repression may represent a new direction for the treatment of MLLr AML.

Lysophosphatidic acid protects cervical cancer HeLa cells from apoptosis induced by doxorubicin hydrochloride.

Cervical cancer is one of the most common types of gynecological tumors. Lysophosphatidic acid (LPA), as a bioactive lipid medium, plays an important role in numerous physiological and pathophysiological processes, including the stimulation of cell migration and tumor cell invasion. LPA is increased in the plasma of patients with cervical cancer. Doxorubicin hydrochloride (DOX) is used as a first-line drug in the treatment of cervical cancer in clinics, however, the effect and molecular mechanism of LPA on DOX-induced apoptosis in cervical cancer cells remain unclear. Therefore, the present study aimed to explore the effect and underlying molecular mechanism of LPA on DOX-induced apoptosis in cervical cancer cells. HeLa cells were treated as a control group or with LPA (10 µmol/l), DOX (4 µmol/l) or LPA (10 µmol/l) + DOX (4 µmol/l) for 24 h. Using transmission electron microscopy the results demonstrated that LPA reduced cell death and the degree of chromatin aggregation in DOX-induced HeLa cells. Reverse transcription-quantitative PCR demonstrated that LPA significantly downregulated caspase-3 mRNA expression levels in DOX-induced HeLa cells. Moreover, western blotting demonstrated that LPA significantly reduced caspase-3 and cleaved caspase-3 protein expression levels in DOX-induced HeLa, C33A and SiHa cells. Furthermore, flow cytometry demonstrated that LPA may prevent apoptosis in DOX-induced HeLa cells (P<0.05). Using dichloro-dihydro-fluorescein diacetate assay, it was demonstrated that LPA significantly reduced the intracellular ROS levels induced by DOX. In summary, the present study indicated that LPA may protect HeLa cells from apoptosis induced by DOX. These findings have provided experimental evidence that LPA may be a potential therapeutic target for the treatment of cervical cancer.

The Histone Deacetylase Inhibitor I13 Induces Differentiation of M2, M3 and M5 Subtypes of Acute Myeloid Leukemia Cells and Leukemic Stem-Like Cells.

Acute myeloid leukemia (AML) is a heterogeneous hematologic malignancy characterized by reduced differentiation of myeloid cells and uncontrolled cell proliferation. AML is prone to drug resistance and has a high recurrence rate during treatment with cytarabine-based chemotherapy. Our study aims to explore the cell differentiation effect of a potent histone deacetylase inhibitor (HDACi), I13, and its possible mechanism on AML cell lines (Kasumi-1, KG-1, MOLM-13 and NB4). It has been shown that I13 can significantly inhibit proliferation and colony formation of these AML cells by inducing cell differentiation coupled with cell-cycle exit at G0/G1. Mechanically, I13 presented the property of HDAC inhibition, as assessed by the acetylation of histone H3, which led to the differentiation of Kasumi-1 cells. In addition, the HDAC inhibition of I13 likely dictated the activation of the antigen processing and presentation pathway, which maybe has the potential to promote immune cells to recognize leukemic cells and respond directly against leukemic cells. These results indicated that I13 could induce differentiation of M3 and M5 subtypes of AML cells, M2 subtype AML cells with t(8;21) translocation and leukemic stem-like cells. Therefore, I13 could be an alternative compound which is able to overcome differentiation blocks in AML.

Histone Deacetylase Inhibitor I3 Induces the Differentiation of Acute Myeloid Leukemia Cells with t (8; 21) or MLL Gene Translocation and Leukemic Stem-Like Cells.

Acute myeloid leukemia (AML) is a heterogeneous disorder characterized by the clonal expansion and differentiation arrest of leukemic cells in peripheral blood and bone marrow. Though the treatment using cytarabine-based protocol for AML patients with t (8; 21) translocation has improved the 5-year overall survival rate, drug resistance continues to be the principal limiting factor for the cure of the disease. In addition, very few AML patients with mixed lineage leukemia gene rearrangements (MLLr) have a desirable outcome. This study evaluated the cell differentiation effect of a potent HDAC (histone deacetylase) inhibitor, I3, and its possible mechanism on the AML cells with t (8; 21) translocation or MLLr and leukemic stem-like cells (Kasumi-1, KG-1, MOLM-13, and THP-1). I3 exhibited efficient anti-proliferative activity on these cells via promoting cell differentiation, accompanied by the cell cycle exit at G0/G1. Importantly, I3 showed the properties of HDAC inhibition, as assessed by the acetylation of histones H3 and H4, which resulted in blocking the activation of the VEGF (vascular endothelial growth factor)-MAPK (mitogen-activated protein kinase) signaling pathway in the Kasumi-1 cell line. These data demonstrate that I3 could be a potent chromatin-remodeling agent to surmount the differentiation block in AML patients, including those with t (8; 21) translocation or MLLr, and could be a potent and selective agent for AML treatment.

Exploring the oncogenic roles of LINC00857 in pan-cancer.

Although aberrant LINC00857 expression may play a key role in oncogenesis, no research has analyzed the pan-cancer oncogenic roles of LINC00857, particularly in tumor immunology. Here, we integrated data from several databases to analyze the characteristics of LINC00857 in pan-cancer. We found that LINC00857 was overexpressed and correlated with a poor prognosis in a variety of cancers. Furthermore, high-expression of LINC00857 was negatively associated with immune cell infiltration and immune checkpoint gene expression. Notably, LINC00857 expression was negatively related to microsatellite instability and tumor mutation burden in colorectal cancer, implying poor reaction to immunotherapy when LINC00857 was highly expressed. Targeting LINC00857 could dramatically impair the proliferative ability of colorectal cancer cells. After RNA-sequencing in HCT116 cells, gene set enrichment analysis showed that LINC00857 may accelerate cancer progression by inhibiting the ferroptosis pathway and promoting glycolipid metabolism in colorectal cancer. Screening by weighted gene co-expression network analysis determined PIWIL4 as a target of LINC00857, which also performed an immunosuppressive role in colorectal cancer. Based on the structure of PIWIL4, a number of small molecule drugs were screened out by virtual screening and sensitivity analysis. In summary, LINC00857 expression was closely correlated with an immunosuppressive microenvironment and may be a novel diagnostic and prognostic biomarker for diverse cancers. The LINC00857/PIWIL4 axis may be predictive biomarkers for immunotherapy and valuable molecular targets for malignant tumors.

Honokiol Induces Ferroptosis by Upregulating HMOX1 in Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is one of the malignant hematological cancers with high mortality. Finding a more effective and readily available treatment is of the utmost importance. Here, we aimed to identify the anti-leukemia effect of a natural small molecule compound honokiol on a panel of AML cell lines, including THP-1, U-937, and SKM-1, and explored honokiol's potential biological pathways and mechanisms. The results showed that honokiol decreased the viability of the targeted AML cells, induced their cell cycle arrest at G0/G1 phase, and inhibited their colony-formation capacity. Honokiol also triggers a noncanonical ferroptosis pathway in THP-1 and U-937 cells by upregulating the level of intracellular lipid peroxide and HMOX1 significantly. Subsequent studies verified that HMOX1 was a critical target in honokiol-induced ferroptosis. These results reveal that honokiol is an effective anti-leukemia agent in AML cell lines and may be a potential ferroptosis activator in AML.

JMJD1C Regulates Megakaryopoiesis in In Vitro Models through the Actin Network.

The histone demethylase JMJD1C is associated with human platelet counts. The JMJD1C knockout in zebrafish and mice leads to the ablation of megakaryocyte-erythroid lineage anemia. However, the specific expression, function, and mechanism of JMJD1C in megakaryopoiesis remain unknown. Here, we used cell line models, cord blood cells, and thrombocytopenia samples, to detect the JMJD1C expression. ShRNA of JMJD1C and a specific peptide agonist of JMJD1C, SAH-JZ3, were used to explore the JMJD1C function in the cell line models. The actin ratio in megakaryopoiesis for the JMJDC modulation was also measured. Mass spectrometry was used to identify the JMJD1C-interacting proteins. We first show the JMJD1C expression difference in the PMA-induced cell line models, the thrombopoietin (TPO)-induced megakaryocyte differentiation of the cord blood cells, and also the thrombocytopenia patients, compared to the normal controls. The ShRNA of JMJD1C and SAH-JZ3 showed different effects, which were consistent with the expression of JMJD1C in the cell line models. The effort to find the underlying mechanism of JMJD1C in megakaryopoiesis, led to the discovery that SAH-JZ3 decreases F-actin in K562 cells and increases F-actin in MEG-01 cells. We further performed mass spectrometry to identify the potential JMJD1C-interacting proteins and found that the important Ran GTPase interacts with JMJD1C. To sum up, JMJD1C probably regulates megakaryopoiesis by influencing the actin network.

Did the modern Yellow River form at the Mid-Pleistocene transition?

The incision of the Sanmen Gorge marks the birth of the modern Yellow River, but its timing varies from the late Miocene-early Pliocene to the late Pleistocene (∼0.15 Ma), and the suggested forcing mechanisms vary from the uplift of the Tibetan Plateau to global climate change. Here, we report sedimentologic, geochronologic, and provenance data from a drill core near the Sanmen Gorge, the last gorge along the main course of the Yellow River. Our results indicate that typical river channel deposits, with detritus from the Ordos Block in the upstream regions, started to accumulate in the Sanmen Gorge at ∼1.25 Ma. When integrated with river terrace evidence from the upstream and downstream regions, the results provide robust evidence that the final integration of the modern Yellow River occurred at ∼1.25 Ma, consistent with the beginning of the Mid-Pleistocene transition (MPT). We propose that the accelerated lowering of eustatic sea level during the MPT may play as important a role as tectonism in driving the birth and evolution of the modern Yellow River.