• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.145-155
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• 2022

Multidrug resistance of tumors has been a severe obstacle to the success of cancer chemotherapy. The study wants to investigate the reversal effects of imperatorin (IMP) on doxorubicin (DOX) resistance in K562/DOX leukemia cells, A2780/Taxol cells and in NOD/SCID mice, to explore the possible molecular mechanisms. K562/DOX and A2780/Taxol cells were treated with various concentrations of DOX and Taol with or without different concentrations of IMP, respectively. K562/DOX xenograft model was used to assess anti-tumor effect of IMP combined with DOX. MTT assay, Rhodamine 123 efflux assay, RT-PCR, and Western blot analysis were determined in vivo and in vitro. Results showed that IMP significantly enhanced the cytotoxicity of DOX and Taxol toward corresponding resistance cells. In vivo results illustrated both the tumor volume and tumor weight were significantly decreased after 2-week treatment with IMP combined with DOX compared to the DOX alone group. Western blotting and RT-PCR analyses indicated that IMP downregulated the expression of P-gp in K562/DOX xenograft tumors in NOD/SCID mice. We also evaluated glycolysis and glutamine metabolism in K562/DOX cells by measuring glucose consumption and lactate production. The results revealed that IMP could significantly reduce the glucose consumption and lactate production of K562/DOX cells. Furthermore, IMP could also remarkably repress the glutamine consumption, α-KG and ATP production of K562/DOX cells. Thus, IMP may sensitize K562/DOX cells to DOX and enhance the antitumor effect of DOX in K562/DOX xenograft tumors in NOD/SCID mice. IMP may be an adjuvant therapy to mitigate the multidrug resistance in leukemia chemotherapy.

• Journal of Life Science
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• v.23 no.2
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• pp.197-206
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• 2013

The present study investigated whether leukemia-maintaining cells reside in a differentiation-resistant fraction using a megakaryocytic differentiation model of K562 cells. Treatment with phorbol-12-myristate-13-acetate (PMA) significantly inhibited the colony-forming efficiency of the K562 cells. At a PMA concentration of 1 nM or higher, colony was not formed, but approximately 40% of K562 cells still survived in soft agar. Approximately 70% of colony-forming cells that were isolated following the removal of PMA after exposure to the agent were differentiated after treatment with 10 nM PMA for 3 days. The differentiation rate of the colony-forming cells was gradually increased and reached about 90% 6 weeks after colony isolation, which was comparable to the level of a PMA-treated K562 control. Meanwhile, imatinib-resistant variants from the K562 cells, including K562/R1, K562/R2, and K562/R3 cells, did not show any colony-forming activity, and most imatinib-resistant variants were CD44 positive. After 4 months of culture in drug-free medium, the surface level of CD44 was decreased in comparison with primary imatinib-resistant variants, and a few colonies were formed from K562/R3 cells. In these cells, Bcr-Abl, which was lost in the imatinib-resistant variants, was re-expressed, and the original phenotypes of the K562 cells were partially recovered. These results suggest that leukemia-maintaining cells might reside in a differentiation-resistant population. Differentiation therapy to eliminate leukemia-maintaining cells could be a successful treatment for leukemia if the leukemia-maintaining cells were exposed to a differentiation inducer for a long time and at a high dose.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7501-7508
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• 2013

Background: Chronic myeloid leukemia (CML) is a myeloproliferative disorder of hematopoietic stem cell scarrying the Philadelphia (Ph) chromosome and an oncogenic BCR-ABL1 fusion gene. The tyrosine kinase inhibitor (TKI) of BCR-ABL1 kinase is a treatment of choice for control of CML. Objective: Recent studies have demonstrated that miRNAs within exosomes from cancer cells play crucial roles in initiation and progression. This study was performed to assess miRNAs within exosomes of K562 cells. Methods: miRNA microarray analysis of K562 cells and K562 cell-derived exosomes was conducted with the 6th generation miRCURYTM LNA Array (v.16.0). Gene ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were also carried out. GO terms and signaling pathways were categorized into 66 classes (including homophilic cell adhesion, negative regulation of apoptotic process, cell adhesion) and 26 signaling pathways (such as Wnt). Results: In exosomes, 49 miRNAs were up regulated as compared to K562 cells, and two of them were further confirmed by quantitative real-time PCR. There are differentially expressed miRNAs between K562 cell derived-exosomes and K562 cells. Conclusion: Selectively expressed miRNAs in exosomes may promote the development of CML via effects on interactions (e.g. adhesion) of CML cells with their microenvironment.

• Korean Journal of Clinical Laboratory Science
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• v.39 no.2
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• pp.68-75
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• 2007

After reports on regression of cancer in humans and animals infected with microbial pathogens date back more than 100 years, much effort has been spent over the years in developing a wild type or attenuated bacterial and purified bacterial proteins for the treatment of cancer. Pseudomonas aeruginosa exotoxin A (ETA) is known to inhibit cell growth and trigger significant cell death in various cancer cells. Although ETA induces apoptosis of cancer cells, its exact mechanism of action is not known yet. Four different assays were performed in this study: morphological assessment of apoptotic cells, cell cytotoxity, annexin-V binding assay, and cell cycle analysis. The proliferation and survival of the K-562 cells treated with ETA were decreased in a dose dependent manner. In addition, the apoptotic body of K-562 cells was induced by ETA treatment in a dose dependent manner. The ETA-induced apoptosis was confirmed by annexin-V binding assay. Flow cytometric analysis was examined to ascertain whether ETA could arrest the cell cycle at the sub-G1 phase. Our results suggest that P. aeruginosa ETA inhibits cell growth and induces apoptosis in human leukemia K-562 cells.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.11
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• pp.4555-4561
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• 2014

Background: Silencing due to methylation of suppressor of cytokine signaling-3 (SOCS-3), a negative regulator gene for the JAK/STAT signaling pathway has been reported to play important roles in leukemogenesis. Imatinib mesylate is a tyrosine kinase inhibitor that specifically targets the BCR-ABL protein and induces hematological remission in patients with chronic myeloid leukemia (CML). Unfortunately, the majority of CML patients treated with imatinib develop resistance under prolonged therapy. We here investigated the methylation profile of SOCS-3 gene and its downstream effects in a BCR-ABL positive CML cells resistant to imatinib. Materials and Methods: BCR-ABL positive CML cells resistant to imatinib (K562-R) were developed by overexposure of K562 cell lines to the drug. Cytotoxicity was determined by MTS assays and $IC_{50}$ values calculated. Apoptosis assays were performed using annexin V-FITC binding assays and analyzed by flow cytometry. Methylation profiles were investigated using methylation specific PCR and sequencing analysis of SOCS-1 and SOCS-3 genes. Gene expression was assessed by quantitative real-time PCR, and protein expression and phosphorylation of STAT1, 2 and 3 were examined by Western blotting. Results: The $IC_{50}$ for imatinib on K562 was 362nM compared to 3,952nM for K562-R (p=0.001). Percentage of apoptotic cells in K562 increased upto 50% by increasing the concentration of imatinib, in contrast to only 20% in K562-R (p<0.001). A change from non-methylation of the SOCS-3 gene in K562 to complete methylation in K562-R was observed. Gene expression revealed down-regulation of both SOCS-1 and SOCS-3 genes in resistant cells. STAT3 was phosphorylated in K562-R but not K562. Conclusions: Development of cells resistant to imatinib is feasible by overexposure of the drug to the cells. Activation of STAT3 protein leads to uncontrolled cell proliferation in imatinib resistant BCR-ABL due to DNA methylation of the SOCS-3 gene. Thus SOCS-3 provides a suitable candidate for mechanisms underlying the development of imatinib resistant in CML patients.

• Radiation Oncology Journal
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• v.21 no.3
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• pp.227-237
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• 2003

Purpose: The human chronic myelogenous leukemia cell line, K562, expresses the chimeric bcr-abl oncoprotein, whose deregulated protein tyrosine kinase activity antagonizes via DNA damaging agents. Previous experiments have shown that nanomolar concentrations of herbimycin A (HWA) coupled with X-irradiation have a synergistic effect in inducing apoptosis in the Ph-positive K562 leukemia cell line, but genistein, a PTK inhibitor, is non selective for the radiation-induced apoptosils on $p210^{bcr/abl}$ protected K562 cells. In these experiments, the cytoplasmic signal transduction pathways, the Induction on a number of transcription factors and the differential gene expression in this model were investigated. Materials and Methids: K562 cells in the exponential growth phase were used in this study. The cells were irradiated with 0.5-12 Gy, using a 6 Mev Linac (Clinac 1800, Varian, USA). Immediately after irradiation, the cells were treated with $0.25/muM$ of HMA and $25/muM$ of genistein, and the expressions and the activities of abl kinase, MAPK family, NF- kB, c-fos, c-myc, and thymidine kinase1 (TK1) were examined. The differential gene expressions induced by PTK inhibitors were also investigated. Results: The modulating effects of herbimycin A and genistein on the radiosensitivity of K562 cells were not related to the bcr-abl kinase activity. The signaling responses through the MAPK family of proteins, were not involved either in association with the radiation-induced apoptosis, which is accelerated by HMA, the expression of c-myc was increased. The combined treatment of genistein, with irradiation, enhanced NF- kB activity and the TK1 expression and activity. Conclusion: The effects of HMA and genistein on the radiosensitivity on the K562 cells were not related to the bcr-abl kinase activity in this study, another signaling pathway, besides the WAPK family responses to radiation to K562 cells, was found. Further evaluation using this model will provide valuable information for the optional radiosensitization or radioprotection.

• Korean Journal of Veterinary Research
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• v.29 no.2
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• pp.51-57
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• 1989

This study was performed to investigate the toxicity of ochratoxin A (OA) to the chromosomes of $K_{562}$ tumor cell-line in vitro. The results of this experiment were as follows: 1) Chromosomes of $K_{562}$tumor cell-line resulted in pseudotriploidy on the control group. Chromosomes of $K_{562}$ tumor cell-line treated with OA resulted in heteroploidy compared with the control group. The mean number of chromosomes in the karyotype of the control group (60) were 7 in the A group, 5 in the B group, 20 in the C+X group, 7 in the D group, 9 in the E group, 6 in the F group, and 6 in the G+Y group respectively. The number of chromosomes were increased as follows: Treating with $0.7{\mu}M$ OA, the number of chromosomes were increased one in E and F group, two in G+Y group compared with control group. In treated with $1.5{\mu}M$ OA, the increasing number of chromosome was one in E and F group. In treated with $3{\mu}M$ OA, E and F group was increased one and G+Y group were increased two chromosomes compared with control group. But in treated with $6{\mu}M$ OA, the number of chromosome in G+Y group was decreased one. 2) $K_{562}$ tumor cell line treated with OA showed Philadelphia-Chromosome in the long arm of the G group karyotype chromosome. The rate of chromosome aberration in $K_{562}$ tumor cell-line treated with OA was 77% in $0.7{\mu}M$ OA group, 71% in $1.5{\mu}M$ OA group, 82% in $3{\mu}M$ OA group and 94% in $6{\mu}M$ OA group respectively. The rate of chromosome aberration of $K_{562}$ tumor cell-line treated with OA was high in the high dose level of OA, and chromosome aberration of $K_{562}$ tumor cell-line treated with OA showed deletion, minute, dicentric-chromosome and translocation in the long arm of the C-group karyotype. As a result of this study, the toxicity of OA showed deletion, minute, dicentric-chromosome and translocation in the long arm of the C-group karyotype, and then, the toxicity of OA resulted in the damage to RNA and protein synthesis in $K_{562}$ tumor cell-line, and the C-group karyotype of $K_{562}$ tumor cell-line was target of the toxicity of OA.

• Archives of Pharmacal Research
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• v.19 no.5
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• pp.416-422
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• 1996

Twenty one phenylacetylshikonin analogues were synthesized from various subsitituted phenyl acetic acids and their cytotoxicity values against A549, K562 and L1210 cell lines and antitumor action in mice bearing S-180 cells were measured. All of phenylacetylshikonin analogues expressed a potent cytotoxicity $(ED_{50}, 0.1-1.80{\mu}g/ml)$ against L1210 and K562 cells. L1210 cells were the most sensitive to shikonin analogues among these cells. Except 4-methosyphenylacetylshikonin $(0.098 {\mu}g/ml)$, and a-acetoxyphenylacetylshikonin $(0.10 {\mu}g/ml)$, all other shikonin derivatives sshowed higher $ED_{50}$ values than phenylacetylshikonin $(0.13{\mu}g/ml)$, in L1210. In K562 cell, a-substitution of phenylacetylshikonin $(0.1{\mu}g/ml)$, while other subsitutions increased it slightly; 4-methoxyphenylacetylshikonin $(0.033{\mu}g/ml)$ showed a exceptionally good cytotoxicity against K562 cell. 4-Halogenation tended to decrease the cytotoxic effect on L1210 cells, while it enhanced the effect on K562; 4-bromophenylacetyl $$[ED_{50};(L1210)=1.76{\mu}g/ml, ;ED_{50};(K 562)=0.32 {\mu}g/ml]$$ and 4-chlorophenylacetyl shikonin $$[ED_{50};(L1210)=1.64 {\mu}g/ml, ;ED_{50};(K562)=0.32 {\mu}g/ml]$$. In contrast, A549 cells were much less sensitive to these shikonin analogues which showed $ED_{50}$ values of$1.5-1.35 {\mu}g/ml)$.Most of phenylacetylshikonin derivatives showed good antitumor activity in mice bearing S-180 cells. a-A-cetoxyphenylacetylshikonin and 4-dimethylaminophenylacetylshikonin showed highest T/C value (192-195%), implying that introduction of a-acetyl or of 4-dimethylamino group enhanced the antitumor activity as shown for 4-dimethylaminophenylacetylshikonin (T/C, 192%). It might be due to improvement of water solubility by dimethylamino group in the molecule.

• Molecules and Cells
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• v.23 no.2
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• pp.138-144
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• 2007

Previously we showed that the human GM3 synthase gene was expressed during the induction of megakaryocytic differentiation in human leukemia K562 cells by phorbol 12-myristate 13-acetate (PMA). In this study we found that treatment of PMA-induced K562 cells with $G{\ddot{o}}6976$, a specific inhibitor of PKC, and U0126, an inhibitor of the extracellular signal-regulated kinase (ERK) reduced expression of GM3 synthase, whereas wortmannin, an inhibitor of phosphoinositide 3-kinase (PI3K) did not. Moreover, activation of ERK and cAMP response element binding protein (CREB) was prevented by pretreatment with $G{\ddot{o}}6976$ and U0126. PMA stimulated the promoter activity of the 5'-flanking region from -177 to -83 region of the GM3 synthase gene, and mutation or deletion of a CREB site located around -143 of the promoter reduced PMA-stimulated promoter activity, as did the inhibitors $G{\ddot{o}}6976$ and U0126. Our results demonstrate that induction of GM3 synthase during megakaryocytic differentiation in PMA-stimulated human leukemia K562 cells depends upon the PKC/ERK/CREB pathway.

• Archives of Pharmacal Research
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• v.18 no.5
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• pp.301-307
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• 1995

In the particulate fraction obtained from PKC-down regulated K562 cells by treatment for 24 h with 200nM TPA, phosphorylation of two proteins with molecular weight, 100 kDa and 23 kDa (designated p100 and p23, respectvely) was depleted and addition of exogenous purified PKC to this fraction failed to testore their phosphorylation. However, in the soluble fraction, all of phosphoproteins abolished by long-term treatment with TPA were restored by exogenously added PKC. Phosphorylation of two proteins was increased by short-term tretment (20 min), and diminished with the persistant exposure to TPA as well as at a concentration as low as 1nM. When K562 cells were treated with 1 nM and 200 nM TPA for 24 h, phosphorylation of p100 was restored with or without exogenous PKC on 2-3day and 6day after removal of treated TPA, respectively. Two-dimensional electrophoresis of phosphoproteins revealed that phosphorylated p100 (pl=5.9) and p66 species were completely absent from the particulate fraction of K562 cells treated with 200nM TPA for 24 h. These results suggest that the interaction of sensitive endogenous substrates, p100 and p23 with the plasma membrane might be regulated by PKC-down regulation without displacement to the cytosol and the interaction of p100 with the membrane might be reveersible.