Improving prime editing with an endogenous small RNA-binding protein.

Prime editing enables the precise modification of genomes through reverse transcription of template sequences appended to the 3' ends of CRISPR-Cas guide RNAs1. To identify cellular determinants of prime editing, we developed scalable prime editing reporters and performed genome-scale CRISPR-interference screens. From these screens, a single factor emerged as the strongest mediator of prime editing: the small RNA-binding exonuclease protection factor La. Further investigation revealed that La promotes prime editing across approaches (PE2, PE3, PE4 and PE5), edit types (substitutions, insertions and deletions), endogenous loci and cell types but has no consistent effect on genome-editing approaches that rely on standard, unextended guide RNAs. Previous work has shown that La binds polyuridine tracts at the 3' ends of RNA polymerase III transcripts2. We found that La functionally interacts with the 3' ends of polyuridylated prime editing guide RNAs (pegRNAs). Guided by these results, we developed a prime editor protein (PE7) fused to the RNA-binding, N-terminal domain of La. This editor improved prime editing with expressed pegRNAs and engineered pegRNAs (epegRNAs), as well as with synthetic pegRNAs optimized for La binding. Together, our results provide key insights into how prime editing components interact with the cellular environment and suggest general strategies for stabilizing exogenous small RNAs therein.

[Prognostic Value of IGF2BP3 Gene Expression Levels in Patients with Acute Myeloid Leukemia].

OBJECTIVE: To investigate the relationship between IGF2BP3 gene expression and prognosis in patients with acute myeloid leukemia (AML). METHODS: High throughput transcriptome sequencing was performed on bone marrow primary leukemia cells from 27 patients with AML in our center, the relationship between IGF2BP3 expression levels and clinical characteristics were analyzed and verify the samples from patients with newly treated AML and refractory AML. The expression level of IGF2BP3 gene were analyzed in 20 healthy subjects and 26 patients with AML. The expression of IGF2BP3 in two anthracycline-resistant cell lines (HL60/ADR, K562/ADR) was detected by RT-qPCR and Western blot, and the expression difference of IGF2BP3 was compared with that in sensitive cells (HL60, K562). The relationship between the expression level of IGF2BP3 in patients with AML and prognostic were analyzed through data analysis of 746 patients with AML, and the prognostic value of IGF2BP3 in AML was analyzed by multivariate Cox regression analysis. RESULTS: In the bone marrow primary leukemia cells of 27 AML patients in our center, the expression level of IGF2BP3 in patients with refractory AML was significantly higher than that in chemotherapy sensitive patients (P =0.0343). The expression of IGF2BP3 in leukemia patients with extramedullary infiltration (EMI) was significantly higher than that in AML patients without extramedullary infiltration (P =0.0049). Compared with healthy subjects (n=20), IGF2BP3 expression in AML patients (n=26) was higher (P =0.0009). The expression of IGF2BP3 mRNA in the anthracycline resistant cell lines (HL60/ADR, K562/ADR) was significantly higher than that in the sensitive cell lines (K562/ADR vs K562,P =0.0430; HL60/ADR vs HL60, P =0.7369). Western blot results showed that the expression of IGF2BP3 protein in mycin resistant cells was significantly higher than that in sensitive cells (P < 0.001). qPCR results showed that the expression level of IGF2BP3 mRNA in refractory AML patients was significantly higher than that in patients with chemotherapy sensitive (P =0.002). High expression of IGF2BP3 was associated with poor prognosis in AML (P < 0.05) in 3 large sample cohorts of AML patients. Univariate and multivariate prognostic analyses demonstrated that high expression of IGF2BP3 was significantly associated with shorter event-free survival (EFS, HR=1.887, P =0.024) and overall survival (OS, HR=1.619, P =0.016). CONCLUSION: The high expression of IGF2BP3 gene may be an important factor in the poor prognosis of AML, suggesting that IGF2BP3 gene may be a new molecular marker for the clinical prognosis evaluation and treatment strategy of AML.

[Reversal Effect of Arctigenin on the Drug Resistance in Leukemia K562/A02 Cells and Its Mechanism].

OBJECTIVE: To study the effect of arctigenin(ARG) on adriamycin(ADM) resistance of leukemia cell line K562/A02 and the underlying mechanism. METHODS: Human leukemia cell line K562 and ADM-resistant cell line K562/A02 were cultured and treated with 2.5-50 µmol/L ADM. Cell proliferation was measured using CCK-8 method, and half maximal inhibitory concentration (IC50) was calculated. K562/A02 cells were treated with different concentrations of ARG (1, 2, 4, 8, 16 mmol/L) to detect the effect of ARG on K562/A02 cells, and a suitable concentration (2 mmol/L) was selected for subsequent experiments. K562/A02 cells were treated with 2 mmol/L ARG and 5 µmol/L ADM, and cell apoptosis was detected by flow cytometry, the expression of P-gp, MRP, cleaved caspase-3, Bax, Bcl-2 proteins and the TLR4/NF-κB signaling pathway-related proteins were measured by Western blot. TLR4 overexpression plasmid was transfected into K562/A02 cells which were co-treated with ARG and ADM, then drug sensitivity and cell apoptosis were measured. RESULTS: The IC50 value of ADM on K562/A02 cells was 36.57 µmol/L, which was significantly higher than that on K562 cells (1.30 µmol/L). ARG with a concentration of ≤2 mmol/L did not have a significant effect on K562/A02 cells. 2 mmol/L ARG significantly reduced the IC50 of ADM on K562/A02 cells. In 5 µmol/L ADM-treated K562/A02 cells, compared with the control group, the apoptosis rate of K562/A02 cells in the ARG group was significantly increased, the expressions of cleaved caspase-3, Bax proteins were significantly upregulated, the expressions of P-gp, MRP, Bcl-2, TLR4, MyD88, and p-NF-κB proteins were significantly downregulated, and the differences were statistically significant (P < 0.05). After transfection with TLR4 overexpression plasmid, the sensitivity of ARG-treated K562/A02 cells to ADM was reduced (P < 0.05), the cell apoptosis was decreased, and the expressions of P-gp, MRP, Bcl-2 and TLR4/NF-κB signaling pathway-related proteins were significantly elevated, while the expressions of cleaved caspase-3 and Bax proteins were significantly decreased (all P < 0.05). CONCLUSION: ARG may reverse the resistance of human leukemia cell line K562/A02 to ADM by inhibiting TLR4/NF-κB signaling pathway.

The Effects of the Steroids 5-Androstenediol and Dehydroepiandrosterone and Their Synthetic Derivatives on the Viability of K562, HeLa, and Wi-38 Cells and the Luminol-Stimulated Chemiluminescence of Peripheral Blood Mononuclear Cells from Healthy Volunteers.

In order to evaluate the role of substituents at 3-C and 17-C in the cytotoxic and cytoprotective actions of DHEA and 5-AED molecules, their derivatives were synthesized by esterification using the corresponding acid anhydrides or acid chlorides. As a result, seven compounds were obtained: four DHEA derivatives (DHEA 3-propionate, DHEA 3-butanoate, DHEA 3-acetate, DHEA 3-methylsulfonate) and three 5-AED derivatives (5-AED 3-butanoate, 5-AED 3,17-dipropionate, 5-AED 3,17-dibutanoate). All of these compounds showed micromolar cytotoxic activity toward HeLa and K562 human cancer cells. The maximum cytostatic effect during long-term incubation for five days with HeLa and K562 cells was demonstrated by the propionic esters of the steroids: DHEA 3-propionate and 5-AED 3,17-dipropionate. These compounds stimulated the growth of normal Wi-38 cells by 30-50%, which indicates their cytoprotective properties toward noncancerous cells. The synthesized steroid derivatives exhibited antioxidant activity by reducing the production of reactive oxygen species (ROS) by peripheral blood mononuclear cells from healthy volunteers, as demonstrated in a luminol-stimulated chemiluminescence assay. The highest antioxidant effects were shown for the propionate ester of the steroid DHEA. DHEA 3-propionate inhibited luminol-stimulated chemiluminescence by 73% compared to the control, DHEA, which inhibited it only by 15%. These data show the promise of propionic substituents at 3-C and 17-C in steroid molecules for the creation of immunostimulatory and cytoprotective substances with antioxidant properties.

Multicenter integrated analysis of noncoding CRISPRi screens.

The ENCODE Consortium's efforts to annotate noncoding cis-regulatory elements (CREs) have advanced our understanding of gene regulatory landscapes. Pooled, noncoding CRISPR screens offer a systematic approach to investigate cis-regulatory mechanisms. The ENCODE4 Functional Characterization Centers conducted 108 screens in human cell lines, comprising >540,000 perturbations across 24.85 megabases of the genome. Using 332 functionally confirmed CRE-gene links in K562 cells, we established guidelines for screening endogenous noncoding elements with CRISPR interference (CRISPRi), including accurate detection of CREs that exhibit variable, often low, transcriptional effects. Benchmarking five screen analysis tools, we find that CASA produces the most conservative CRE calls and is robust to artifacts of low-specificity single guide RNAs. We uncover a subtle DNA strand bias for CRISPRi in transcribed regions with implications for screen design and analysis. Together, we provide an accessible data resource, predesigned single guide RNAs for targeting 3,275,697 ENCODE SCREEN candidate CREs with CRISPRi and screening guidelines to accelerate functional characterization of the noncoding genome.

Use of CRISPR/Cas9 with Homology-Directed Repair to Gene-Edit Topoisomerase IIß in Human Leukemia K562 Cells: Generation of a Resistance Phenotype.

DNA topoisomerase IIß (TOP2ß/180; 180 kDa) is a nuclear enzyme that regulates DNA topology by generation of short-lived DNA double-strand breaks, primarily during transcription. TOP2ß/180 can be a target for DNA damage-stabilizing anticancer drugs, whose efficacy is often limited by chemoresistance. Our laboratory previously demonstrated reduced levels of TOP2ß/180 (and the paralog TOP2α/170) in an acquired etoposide-resistant human leukemia (K562) clonal cell line, K/VP.5, in part due to overexpression of microRNA-9-3p/5p impacting post-transcriptional events. To evaluate the effect on drug sensitivity upon reduction/elimination of TOP2ß/180, a premature stop codon was generated at the TOP2ß/180 gene exon 19/intron 19 boundary (AGAA//GTAA→ATAG//GTAA) in parental K562 cells (which contain four TOP2ß/180 alleles) by CRISPR/Cas9 editing with homology-directed repair to disrupt production of full-length TOP2ß/180. Gene-edited clones were identified and verified by quantitative polymerase chain reaction and Sanger sequencing, respectively. Characterization of TOP2ß/180 gene-edited clones, with one or all four TOP2ß/180 alleles mutated, revealed partial or complete loss of TOP2ß mRNA/protein, respectively. The loss of TOP2ß/180 protein correlated with decreased (2-{4-[(7-chloro-2-quinoxalinyl)oxy]phenoxy}propionic acid)-induced DNA damage and partial resistance in growth inhibition assays. Partial resistance to mitoxantrone was also noted in the gene-edited clone with all four TOP2ß/180 alleles modified. No cross-resistance to etoposide or mAMSA was noted in the gene-edited clones. Results demonstrated the role of TOP2ß/180 in drug sensitivity/resistance in K562 cells and revealed differential paralog activity of TOP2-targeted agents. SIGNIFICANCE STATEMENT: Data indicated that CRISPR/Cas9 editing of the exon 19/intron 19 boundary in the TOP2ß/180 gene to introduce a premature stop codon resulted in partial to complete disruption of TOP2ß/180 expression in human leukemia (K562) cells depending on the number of edited alleles. Edited clones were partially resistant to mitoxantrone and XK469, while lacking resistance to etoposide and mAMSA. Results demonstrated the import of TOP2ß/180 in drug sensitivity/resistance in K562 cells and revealed differential paralog activity of TOP2-targeted agents.

Targeting mitochondrial bioenergetics by combination treatment with imatinib and dichloroacetate in human erythroleukemic K­562 and colorectal HCT­116 cancer cells.

Tumor malignant cells are characterized by dysregulation of mitochondrial bioenergetics due to the 'Warburg effect'. In the present study, this metabolic imbalance was explored as a potential target for novel cancer chemotherapy. Imatinib (IM) downregulates the expression levels of SCΟ2 and FRATAXIN (FXN) genes involved in the heme­dependent cytochrome c oxidase biosynthesis and assembly pathway in human erythroleukemic IM­sensitive K­562 chronic myeloid leukemia cells (K­562). In the present study, it was investigated whether the treatment of cancer cells with IM (an inhibitor of oxidative phosphorylation) separately, or together with dichloroacetate (DCA) (an inhibitor of glycolysis), can inhibit cell proliferation or cause death. Human K­562 and IM­chemoresistant K­562 chronic myeloid leukemia cells (K­562R), as well as human colorectal carcinoma cells HCT­116 (+/+p53) and (­/­p53, with double TP53 knock-in disruptions), were employed. Treatments of these cells with either IM (1 or 2 µM) and/or DCA (4 mΜ) were also assessed for the levels of several process biomarkers including SCO2, FXN, lactate dehydrogenase A, glyceraldehyde­3­phosphate dehydrogenase, pyruvate kinase M2, hypoxia inducing factor­1a, heme oxygenase­1, NF­κB, stem cell factor and vascular endothelial growth factor via western blot analysis. Computational network biology models were also applied to reveal the connections between the ten proteins examined. Combination treatment of IM with DCA caused extensive cell death (>75%) in K­562 and considerable (>45%) in HCT­116 (+/+p53) cultures, but less in K­562R and HCT­116 (­/­p53), with the latter deficient in full length p53 protein. Such treatment, markedly reduced reactive oxygen species levels, as measured by flow­cytometry, in K­562 cells and affected the oxidative phosphorylation and glycolytic biomarkers in all lines examined. These findings indicated, that targeting of cancer mitochondrial bioenergetics with such a combination treatment was very effective, although chemoresistance to IM in leukemia and the absence of a full length p53 in colorectal cells affected its impact.

Building a Better Defense: Expanding and Improving Natural Killer Cells for Adoptive Cell Therapy.

Natural killer (NK) cells have gained attention as a promising adoptive cell therapy platform for their potential to improve cancer treatments. NK cells offer distinct advantages over T-cells, including major histocompatibility complex class I (MHC-I)-independent tumor recognition and low risk of toxicity, even in an allogeneic setting. Despite this tremendous potential, challenges persist, such as limited in vivo persistence, reduced tumor infiltration, and low absolute NK cell numbers. This review outlines several strategies aiming to overcome these challenges. The developed strategies include optimizing NK cell expansion methods and improving NK cell antitumor responses by cytokine stimulation and genetic manipulations. Using K562 cells expressing membrane IL-15 or IL-21 with or without additional activating ligands like 4-1BBL allows "massive" NK cell expansion and makes multiple cell dosing and "off-the-shelf" efforts feasible. Further improvements in NK cell function can be reached by inducing memory-like NK cells, developing chimeric antigen receptor (CAR)-NK cells, or isolating NK-cell-based tumor-infiltrating lymphocytes (TILs). Memory-like NK cells demonstrate higher in vivo persistence and cytotoxicity, with early clinical trials demonstrating safety and promising efficacy. Recent trials using CAR-NK cells have also demonstrated a lack of any major toxicity, including cytokine release syndrome, and, yet, promising clinical activity. Recent data support that the presence of TIL-NK cells is associated with improved overall patient survival in different types of solid tumors such as head and neck, colorectal, breast, and gastric carcinomas, among the most significant. In conclusion, this review presents insights into the diverse strategies available for NK cell expansion, including the roles played by various cytokines, feeder cells, and culture material in influencing the activation phenotype, telomere length, and cytotoxic potential of expanded NK cells. Notably, genetically modified K562 cells have demonstrated significant efficacy in promoting NK cell expansion. Furthermore, culturing NK cells with IL-2 and IL-15 has been shown to improve expansion rates, while the presence of IL-12 and IL-21 has been linked to enhanced cytotoxic function. Overall, this review provides an overview of NK cell expansion methodologies, highlighting the current landscape of clinical trials and the key advancements to enhance NK-cell-based adoptive cell therapy.

New Derivatives of 1-(3-Methyl-1-Benzofuran-2-yl)Ethan-1-one: Synthesis and Preliminary Studies of Biological Activity.

A set of nine derivatives, including five brominated compounds, was synthesized and the structures of these novel compounds were confirmed using 1H and 13C NMR as well as ESI MS spectra. These compounds were tested on four different cancer cell lines, chronic myelogenous leukemia (K562), prostate cancer (PC3), colon cancer (SW620), human kidney cancer (Caki 1), and on healthy human keratocytes (HaCaT). MTT results reveal that two newly developed derivatives (6 and 8) exhibit selective action towards K562 cells and no toxic effect in HaCat cells. The biological activity of these two most promising compounds was evaluated by trypan blue assay, reactive oxygen species generation, and IL-6 secretion. To investigate the proapoptotic activity of selected compounds, the two following types of tests were performed: Annexin V Apoptosis Detection Kit I and Caspase-Glo 3/7 assay. The studies of the mechanism showed that both compounds have pro-oxidative effects and increase reactive oxygen species in cancer cells, especially at 12 h incubation. Through the Caspase-Glo 3/7 assay, the proapoptotic properties of both compounds were confirmed. The Annexin V-FITC test revealed that compounds 6 and 8 induce apoptosis in K562 cells. Both compounds inhibit the release of proinflammatory interleukin 6 (IL-6) in K562 cells. Additionally, all compounds were screened for their antibacterial activities using standard and clinical strains. Within the studied group, compound 7 showed moderate activity towards Gram-positive strains in antimicrobial studies, with MIC values ranging from 16 to 64 µg/mL.

Saracatinib prompts hemin-induced K562 erythroid differentiation but suppresses erythropoiesis of hematopoietic stem cells.

Human myeloid leukemia cells (such as K562) could be used for the study of erythropoiesis, and mature erythroid markers and globins could be induced during leukemia cell differentiation; however, the pathways involved are different compared with those of hematopoietic stem cells (HSCs).We identified the differentially expressed genes (DEGs) of K562 cells and HSCs associated with stem cells and erythroid differentiation. Furthermore, we showed that hemin-induced differentiation of K562 cells could be induced by serum starvation or treatment with the tyrosine kinase inhibitor saracatinib. However, erythroid differentiation of HSCs was inhibited by the deprivation of the important serum component erythropoietin (EPO) or treatment with saracatinib. Finally, we found that the mRNA expression of K562 cells and HSCs was different during saracatinib-treated erythroid differentiation, and the DEGs of K562 cells and HSCs associated with tyrosine-protein kinase were identified.These findings elucidated the cellular phenomenon of saracatinib induction during erythroid differentiation of K562 cells and HSCs, and the potential mechanism is the different mRNA expression profile of tyrosine-protein kinase in K562 cells and HSCs.

Inhibition of LATS kinases reduces tumorigenicity and increases the sensitivity of human chronic myelogenous leukemia cells to imatinib.

Chronic myelogenous leukemia (CML) is a clonal hematologic malignancy of the myeloid lineage caused by the oncogenic BCR/ABL fusion protein that promotes CML cell proliferation and protects them against drug-induced apoptosis. In this study, we determine LATS1 and LATS2 expression in CML cells derived from patients who are resistant to imatinib (IM) treatment. Significant upregulation of LATS1 and LATS2 was found in these CML patients compared to healthy donors. To further explore whether the expression of LATS1/2 contributes to the IM-resistant phenotype, IM-resistant CML cell lines generated by culturing CML-derived erythroblastic K562 cells in increasing concentrations of IM were used as in vitro models. Up-regulation of LATS1 and LATS2 was observed in IM-resistant K562 cells. Reduction of LATS using either Lats-IN-1 (TRULI), a specific LATS inhibitor, or shRNA targeting LATS1/2 significantly reduced clonogenicity, increased apoptosis and induced differentiation of K562 cells to late-stage erythroid cells. Furthermore, depletion of LATS1 and LATS2 also increased the sensitivity of K562 cells to IM. Taken together, our results suggest that LATS could be one of the key factors contributing to the rapid proliferation, reduced apoptosis, and IM resistance of CML cells. Targeting LATS could be a promising treatment to enhance the therapeutic effect of a conventional BCR/ABL tyrosine kinase inhibitor such as IM.

AI-based Apoptosis Cell Classification Using Phase-contrast Images of K562 Cells.

BACKGROUND/AIM: This study aimed to automate the classification of cells, particularly in identifying apoptosis, using artificial intelligence (AI) in conjunction with phase-contrast microscopy. The objective was to reduce reliance on manual observation, which is often time-consuming and subject to human error. MATERIALS AND METHODS: K562 cells were used as a model system and apoptosis was induced following administration of gamma-secretase inhibitors. Fluorescence staining was applied to detect DNA fragmentation and caspase activity. Cell images were obtained using both phase-contrast and fluorescence microscopy. Two AI models, Lobe(R) and a server-based ResNet50, were trained using these images and evaluated using F-values through five-fold cross-validation. RESULTS: Both AI models demonstrated effectively categorized individual cells into three groups: caspase-negative/no DNA fragmentation, caspase-positive/no DNA fragmentation, and caspase-positive/DNA fragmentation. Notably, the AI models' ability to differentiate cells relied on subtle variations in phase-contrast images, potentially linked to changes in refractive indices during apoptosis progression. Both AI models exhibited high accuracy, with the server-based ResNet50 model showing improved performance through repeated training. CONCLUSION: This study demonstrates the potential of AI-assisted phase-contrast microscopy as a powerful tool for automating cell classification, especially in the context of apoptosis research and the discovery of anticancer substances. By reducing the need for manual labor and enhancing classification accuracy, this approach holds promise for expediting high-throughput cell screening, significantly contributing to advancements in medical diagnostics and drug development.

[Effect of TRIM59 Expression Interference on Daunorubicin Chemosensitivity of Chronic Myeloid Leukemia K562 Cells and Its Mechanism].

OBJECTIVE: To investigate the effect of tripipartite motif 59 (TRIM59) expression interference on the chemosensitivity of daunorubicin (DNR) in chronic myeloid leukemia (CML) K562 cells and the related molecular mechanism. METHODS: The expressions of TRIM59 mRNA in bone marrow tissues of patients with CML and K562 cells were detected by RT-qPCR. Liposome-based transfection technology was used to transfect TRIM59-specific siRNA (si-TRIM59) into K562 cells which then were treated with DNR. The proliferation and apoptosis of cells were detected by CCK-8 assay and flow cytometry, respectively, and the expressions of apoptosis-related protein and Wnt/ß-catenin signaling pathway-related protein were detected by Western blot. RESULTS: Compared with the bone marrow tissue of CML patients at the time of initial treatment, the expression of TRIM59 mRNA in bone marrow tissue of CML patients at the time of chemotherapy resistance was significantly increased (P <0.05). Compared with control group, the cell proliferation inhibition rate and apoptosis rate in si-TRIM59 group and DNR group were significantly increased (P <0.05), the expression of Bax, Caspase3 and Cleaved-Caspase3 protein were significantly increased (P <0.05), while the expressions of Bcl-2, Wnt3α, GSK-3ß protein and the ratio of p-ß-catenin/ß-catenin were significantly decreased (P <0.05). Compared with si-TRIM59 group and DNR group, the proliferation inhibition rate and apoptosis rate of si-TRIM59+DNR group were significantly increased (P <0.05), the expression of Bax, Caspase3 and Cleaved-Caspase3 protein were significantly increased, while the expression of Bcl-2, Wnt3α, GSK-3ß protein and the ratio of p-ß-catenin/ß-catenin were significantly decreased (P <0.05). CONCLUSION: TRIM59 expression interference may enhance the chemosensitivity of K562 cells to DNR, and its mechanism may be related to the regulation of Wnt/ß-catenin signaling pathway.

[Study on the Effect and Mechanism of Tetrandrine on Bone Marrow Mesenchymal Stem Cell-Mediated Drug Resistance in Leukemia].

OBJECTIVE: To explore the role of bone marrow mesenchymal stem cells (BMSC)，an essential element of the bone marrow microenvironment, in multidrug resistance(MDR) of K562 cells, as well as the reversal effect of tetrandrine (TET) on BMSC-mediated MDR and its potential mechanism. METHODS: A mixed co-culture system and a transwell co-culture system for BMSC and K562 cells were established, and the cells were divided into different groups and treated with daunorubicin (DNR) alone or combined with TET and DNR. The CCK-8 assay was used to detect the proliferation of K562 cells in each group, and the cell inhibition rate was calculated. Cytometric bead array (CBA) was used to detect the expression levels of IFN, IL-2, IL-6 and IL-10 in the supernatant of different groups. RT-qPCR and Western blot were used to detected the expression of STAT3 at mRNA and protein levels, respectively. RESULTS: Compared with K562+DNR group, the inhibition rate of DNR on K562 cell proliferation in K562+BMSC+DNR group was significantly decreased (P < 0.05), while the levels of IL-6 in the culture supernatant and phosphorylated STAT3 in K562 cells were significantly increased (P < 0.05). Compared with K562+BMSC+DNR group, the inhibition rate of DNR on K562 cell proliferation in K562+BMSC+DNR+TET group was significantly increased (P < 0.05), while the level of IL-6 and phosphorylated STAT3 was significantly decreased (P < 0.05). CONCLUSION: BMSC can promote the drug resistance of leukemia cells, and TET may reverse the BMSC-mediated drug resistance via inhibiting IL-6/STAT3 signaling pathway.

Selection of reference genes in liproxstatin-1-treated K562 Leukemia cells via RT-qPCR and RNA sequencing.

BACKGROUND: Reverse transcription quantitative polymerase chain reaction (RT-qPCR) can accurately detect relative gene expression levels in biological samples. However, widely used reference genes exhibit unstable expression under certain conditions. METHODS AND RESULTS: Here, we compared the expression stability of eight reference genes (RPLP0, RPS18, RPL13, EEF1A1, ß-actin, GAPDH, HPRT1, and TUBB) commonly used in liproxstatin-1 (Lip-1)-treated K562 cells using RNA-sequencing and RT-qPCR. The expression of EEF1A1, ACTB, GAPDH, HPRT1, and TUBB was considerably lower in cells treated with 20 µM Lip-1 than in the control, and GAPDH also showed significant downregulation in the 10 µM Lip-1 group. Meanwhile, when we used geNorm, NormFinder, and BestKeeper to compare expression stability, we found that GAPDH and HPRT1 were the most unstable reference genes among all those tested. Stability analysis yielded very similar results when geNorm or BestKeeper was used but not when NormFinder was used. Specifically, geNorm and BestKeeper identified RPL13 and RPLP0 as the most stable genes under 20 µM Lip-1 treatment, whereas RPL13, EEF1A1, and TUBB were the most stable under 10 µM Lip-1 treatment. TUBB and EEF1A1 were the most stable genes in both treatment groups according to the results obtained using NormFinder. An assumed most stable gene was incorporated into each software to validate the accuracy. The results suggest that NormFinder is not an appropriate algorithm for this study. CONCLUSIONS: Stable reference genes were recognized using geNorm and BestKeeper but not NormFinder. Overall, RPL13 and RPLP0 were the most stable reference genes under 20 µM Lip-1 treatment, whereas RPL13, EEF1A1, and TUBB were the most stable genes under 10 µM Lip-1 treatment.

Novel betulin derivatives as multidrug reversal agents targeting P-glycoprotein.

Chemotherapy is a powerful means of cancer treatment but its efficacy is compromised by the emergence of multidrug resistance (MDR), mainly linked to the efflux transporter ABCB1/P-glycoprotein (P-gp). Based on the chemical structure of betulin, identified in our previous work as an effective modulator of the P-gp function, a series of analogs were designed, synthesized and evaluated as a source of novel inhibitors. Compounds 6g and 6i inhibited rhodamine 123 efflux in the P-gp overexpressed leukemia cells, K562/Dox, at concentrations of 0.19 µM and 0.39 µM, respectively, and increased the intracellular accumulation of doxorubicin at the submicromolar concentration of 0.098 µM. Compounds 6g and 6i were able to restore the sensitivity of K562/Dox to Dox at 0.024 µM and 0.19 µM, respectively. Structure-activity relationship analysis and molecular modeling revealed important information about the structural features conferring activity. All the active compounds fitted in a specific region involving mainly transmembrane helices (TMH) 4-6 from one homologous half and TMH 7 and 12 from the other, also showing close contacts with TMH 6 and 12. Compounds that bound preferentially to another region were inactive, regardless of their free energy of binding. It should be noted that compounds 6g and 6i were devoid of toxic effects against peripheral blood mononuclear normal cells and erythrocytes. The data obtained indicates that both compounds might be proposed as scaffolds for obtaining promising P-gp inhibitors for overcoming MDR.

A Simple Aptamer-Based Nanoconjugate Assay for Diagnosis of Chronic Myeloid Leukemia.

Chronic myeloid leukemia (CML) as a bone marrow stem cell clonal disease appears from the proliferation of granulocyte cells at all stages of maturation. If the disease diagnosis is not early, patients enter the blastic phase, which decreases their survival rate to 3-6 months. It implies the significance of the early diagnosis of CML. In this study, we introduce a simple array for diagnosis of the K562 cells as the human immortalized myeloid leukemia cell line. The developed aptamer-based biosensor (aptasensor) includes the T2-KK1B10 aptamer strands attached to the surface of mesoporous silica nanoparticles (MSNPs) with the cavities accumulated from rhodamine B and coated by both Ca2+ ions and ATP aptamer. The aptamer-based nanoconjugate can enter the K562 cells through the complexation of the T2-KK1B10 aptamer with the cells. The ATP in the cells and low level of intracellular Ca2+ ion release both the aptamer and ion from the surface of the MSNPs. The liberated rhodamine B results in an increased fluorescence intensity. Fluorescence microscope imaging and flow cytometry histogram display a strong fluorescence emission for the K562 cells (CML cells) exposed to the nanoconjugate in comparison with that for MCF-7 cells. The aptasensor possesses good performance in the blood samples with the advantages of high sensitivity, rapidness, and cost-effectiveness, making it an appropriate tool for the diagnosis of CML disease.

Cellular and DNA Toxicity Study of Triphenyltin Ethyl Phenyl Dithiocarbamate and Triphenyltin Butyl Phenyl Dithiocarbamate on K562, Leukemia Cell Line.

INTRODUCTION: Continuous research for new effective drugs to treat cancer has improved our understanding on the mechanism of action of these drugs and paved new potential for their application in cancer treatments. In this study, organotin compounds known as triphenyltin ethyl phenyl dithiocarbamate and triphenyltin butyl phenyl dithiocarbamate were investigated for their toxicity on leukemia cell line (K562) and non-cancerous cell line (Chang liver cell and lung fibroblast, V79 cell). METHODS: MTT assay was performed to evaluate the cytotoxic effects of both compounds toward the cells after 24, 48 and 72 hours of exposure or treatment. The alkaline comet assay was conducted to determine the DNA damage on K562 cells after been exposed to both compounds for 30, 60 and 90 minutes. RESULTS: The IC50 values obtained from K562 cells ranged from 0.01 to 0.30 µM, whereas for both Chang liver cell and lung fibroblast V79 cell, the values ranged from 0.10 to 0.40 µM. For genotoxicity evaluation, the percentage of damaged DNA is measured as an average of tail moment, and was found to be within 1.20 to 2.20 A.U while the percentage of DNA intensity ranging from 1.50 to 3.50% indicating no genotoxic effects. CONCLUSION: Both compounds are cytotoxic toward leukemia cells and non-cancerous cells but do not exert their genotoxic effects towards leukemia cell.

Three snake venoms from Bothrops genus induced apoptosis and cell cycle arrest in K562 human leukemic cell line.

Cancer is indisputably one of the leading causes of death worldwide. Snake venoms are a potential source of bioactive compounds, complex mixtures constituted mainly of proteins and peptides with several pharmacological possibilities, including the potential to inhibit tumoral cell growth. In the present study, it was evaluated the antitumor effect of crude venom of Bothrops erythromelas (BeV), Bothrops jararaca (from Southern and Southeastern- BjsV and BjsdV, respectively) and Bothrops alternatus (BaV) in in vitro Chronic myeloid leukemia (CML) cancer cell line model. After 24 h of cell exposure to 10 and 50 µg/mL, BjsV, BjsdV, and BaV exerted a decrease in cell viability in both concentrations. BeV was not cytotoxic and, therefore wasn't chosen for further mechanism of action investigation. Furthermore, morphological alterations show modification typical of apoptosis. Also, was observes a significant cell cycle arrest in the S phase by BjsdV and BaV treatment. Flow cytometry evidenced the involvement of changes in the cell membrane permeability and the mitochondrial function by BjsV and BjsdV, corroborating with the triggering of the apoptotic pathway by the venom administration. BjsV, BjsdV, and BaV also led to extensive DNA damage and were shown to modulate the gene expression of transcripts related to the cell cycle progression and suppress the expression of the BCR-ABL1 oncogene. Altogether, these findings suggest that the venoms trigger the apoptosis pathway due to mitochondrial damage and cell cycle arrest, with modulation of intracellular pathways important for CML progression. Thus, indicating the pharmacological potential of these venoms in the development of new antitumoral compounds.

Apoptotic effect of Bulbine Natalensis and Chlorophytum Comosum in myelogenous Leukemia K562 cell line / Efeito apoptótico da natalensia bulbina e do clorofito comoso na linhagem celular mielogênea da leucemia K562

Abstract Bulbine natalensis and Chorophytum comosum are potential medicinal source for the treatment of cancers. Chronic myeloid leukaemia is a hematopoietic stem cells disorder treated by tyrosine kinase inhibitors but often cause recurrence of the leukaemia after cessation of therapy, hence require alternative treatment. This study determines the anti-cancer effect of leaf, root and bulb methanolic and aqueous extracts of B. natalensis and C. comosum in chronic human myelogenous leukaemia (K562) cell line by MTT, Hoechst bis-benzimide nuclear and annexin V stain assays. The root methanolic extract of B. natalensis and C. comosum showed a high cytotoxicity of 8.6% and 16.7% respectively on the K562 cell line at 1,000 μg/ml concentration. Morphological loss of cell membrane integrity causing degradation of the cell and fragmentation were observed in the root methanolic extract of both plants. A high apoptosis (p < 0.0001) was induced in the K562 cells by both leaf and root extracts of the C. comosum compared to the B. natalensis. This study shows both plants possess apoptotic effect against in vitro myelogenous leukaemia which contributes to the overall anti-cancer properties of B. natalensis and C. comosum to justify future therapeutic applications against chronic myelogenous leukaemia blood cancer.

Resumo Bulbine natalensis Baker e Chorophytum comosum (Thunb.) Jacques são potenciais fontes medicinais para o tratamento de cânceres. A Leucemia Mieloide Crônica (LMC) é um distúrbio das células-tronco hematopoiéticas que é tratado com inibidores da tirosina quinase, mas frequentemente, causa recorrência da leucemia após a interrupção da terapia, portanto, requer um tratamento alternativo. Este estudo determinou o efeito anticancerígeno de extratos metanólicos e aquosos de folha, raiz e bulbo de B. natalensis e C. comosum na linhagem celular de leucemia mieloide humana crônica (K562) por ensaios de MTT, Hoechst bis-benzimida nuclear e anexina V. O extrato metanólico da raiz de B. natalensis e C. comosum apresentou alta citotoxidade de 8,6% e 16,7% respectivamente, na linhagem celular K562 com a concentração de 1,000 μg / ml. Perda morfológica da integridade da membrana celular causando degradação dos núcleos, citoplasma e encolhimento celular foi observada no extrato metanólico da raiz de ambas as plantas. Uma alta apoptose (p <0,0001) foi induzida nas células K562 por extratos de folhas e raízes de C. comosum em comparação com B. natalensis. Este estudo mostrou que ambas as plantas possuem efeito apoptótico contra leucemia mieloide in vitro que contribui para as propriedades anticâncer gerais de B. natalensis e C. comosum para justificar futuras aplicações terapêuticas contra câncer de sangue de LMC.