Wan-Seok Kim

Antipathogenic properties of green tea polyphenol epigallocatechin gallate at concentrations below the MIC against enterohemorrhagic escherichia coli O157: H7

The inhibitory effects of green tea polyphenol epigallocatechin gallate (EGCG) on virulence phenotypes and gene expression regulated by quorum sensing (QS) in Escherichia coli O157:H7 were demonstrated at concentrations of 1 to 100 microg/ml, which are lower than the MIC (539 +/- 22 microg/ml). At 25 microg/ml, the growth rate was not affected, but autoinducer 2 concentration, biofilm formation, and swarm motility decreased to 13.2, 11.8, and 50%, respectively. Survival at 5 days of nematodes (Caenorhabditis elegans) that were fed the pathogen without and with EGCG were 47.1 and 76%, respectively. Real-time PCR data indicated decreased transcriptional level in many quorum sensing-regulated virulence genes at 25 microg/ml. Our results suggest that EGCG at concentrations below itsMIC has significant antipathogenic effects against E. coli O157:H7.

Previous best responses can be re-achieved by resumption after imatinib discontinuation in patients with chronic myeloid leukemia: implication for intermittent imatinib therapy.

Although imatinib is considered as a front line therapy in patients with chronic myeloid leukemia (CML), it is still unclear whether transient imatinib discontinuation may adversely affect the outcome. This study was conducted to investigate long-term outcome after discontinuation and resumption of imatinib, and to determine whether intermittent imatinib therapy can be employed in patients with CML. Twenty six Philadelphia chromosome positive (Ph+) patients with CML discontinued imatinib when they achieved complete cytogenetic response (CCyR) or complete molecular response (CMR), and they were retreated with imatinib in case of hematologic, cytogenetic or molecular relapse. Except one patient who progressed and two patients who are in persistent molecular remission without imatinib resumption, all of 23 patients are maintaining the best response achieved after imatinib resumption with a median follow-up of 44 months. This study shows that although imatinib cannot be discontinued completely, intermittent therapy can be considered for the treatment of patients with CML in particular situations.

Analysis of Bcr‐Abl kinase domain mutations in Korean chronic myeloid leukaemia patients: poor clinical outcome of P‐loop and T315I mutation is disease phase dependent

Despite durable responses to imatinib in chronic myeloid leukaemia (CML), mutations in Bcr‐Abl kinase domain (KD) are known to induce imatinib resistance and cause poor clinical outcome. We characterized Bcr‐Abl KD mutations in 137 Korean CML patients with imatinib resistance (n = 111) or intolerance (n = 26) using allele specific oligonucleotide polymerase chain reaction (PCR) and direct sequencing. Seventy (51%) patients harboured 81 mutations of 20 different types with increasing prevalence in advanced phase. Nine (13%) patients had multiple mutations. No mutation was found in intolerant patients. T315I was the most common mutation and P‐loop was the hottest spot in Bcr‐Abl KD. Patients harbouring P‐loop mutation, T315I, or multiple mutations showed poor overall survival and progression free survival compared with patients harbouring other mutations. Survival analysis according to disease phase of mutation being detected and type of mutations provided correlation between P‐loop or T315I mutation and poor overall survival in blast crisis, but not in accelerated phase (AP) or chronic phase (CP), indicating poor clinical outcome of particular mutations depends on disease phase. CML patients with imatinib resistance showed high rate (63%) of mutations in Bcr‐Abl KD and therefore CML patients who do not respond to imatinib should be the candidates for mutation screening as molecular monitoring. Copyright

Structural modeling of V299L and E459K Bcr-Abl mutation, and sequential therapy of tyrosine kinase inhibitors for the compound mutations

Sequential treatment with different tyrosine kinase inhibitors (TKIs) is one of the strategies for handling chronic myeloid leukemia (CML) in which dynamic change in Bcr-Abl kinase domain mutation is often an obstacle faced during TKI therapy. Here we report successful sequential therapy with different TKIs for the CML patient harboring V299L and E459K compound mutations. Molecular monitoring including quantitative analysis of BCR-ABL transcript level and mutation analysis were performed regularly for successful treatment. Additionally a drug-target complex was structurally modeled to investigate influence of amino acid substitutions on drug resistance, and to choose alternative TKI in sequential therapy, suggesting protein structural modeling can be useful approach in selecting alternative TKIs.

Dynamic change of T315I BCR-ABL kinase domain mutation in Korean chronic myeloid leukaemia patients during treatment with Abl tyrosine kinase inhibitors.

We analysed the dynamic change of imatinib‐resistant mutations in BCR‐ABL kinase domain focusing on T315I mutation during dasatinib or nilotinib therapy. Fifty‐five imatinib‐resistant chronic myeloid leukaemia patients (32 patients with imatinib‐resistant mutations and 23 patients without mutation) in different disease phases were treated with dasatinib (median 17.3 months) or nilotinib (median 6.8 months). Among the 32 patients with baseline mutation, mutations including M244V, G250E, E255K, M351T, H396R, S417Y, E450K and E459K disappeared in 8 patients and new mutations were detected in 9 patients, all of which were T315I. Among the 23 patients without baseline mutation, 4 patients showed newly developed mutations including T315I, T315I + E459K, M244V and F359V. The T315I was the most frequently detected mutation in imatinib therapy (16%, 9 of 55) as well as in dasatinib or nilotinib therapy (24%, 11 of 44). Patients with imatinib resistant baseline mutations had a higher rate of mutation development during dasatinib or nilotinib treatment compared to patients without baseline mutations (28% vs. 17%). Copyright

Korean Red Ginseng Extract Enhances the Anticancer Effects of Imatinib Mesylate Through Abrogation p38 and STAT5 Activation in KBM-5 Cells

Although imatinib mesylate (IM) in the treatment of chronic myelogenous leukemia (CML) remains the best example of successful targeted therapy, majority of patients with CML suffer its toxicity profile and develop chemoresistance to existing therapeutic agents. Thus, there is a need to develop novel alternative therapies for the treatment of CML. Here, we investigated whether Korean red ginseng extract (KRGE) could suppress the proliferation and induce chemosensitization in human CML cells. Also, we used a human phospho‐antibody array containing 46 antibodies against signaling molecules to examine a subset of phosphorylation events after treatment. Korean red ginseng extract broadly suppressed the proliferation of five different cell lines, but KRGE was found to be the most potent inducer of apoptosis against KBM‐5 cells. It also abrogated the expression of Bcl‐2 (B‐cell lymphoma 2), Bcl‐xL (B‐cell lymphoma‐extra large), survivin, inhibitors of apoptosis protein 1/2, COX‐2 (Cyclooxygenase‐2), cyclin D1, matrix metalloproteinase‐9, and VEGF (Vascular endothelial growth factor), as well as upregulated the expression of pro‐apoptotic gene products. Interestingly, KRGE also enhanced the cytotoxic and apoptotic effect of IM in KBM‐5 cells. The combination treatment of KRGE and IM caused pronounced suppression of p38 and signal transducer and activator of transcription 5 phosphorylation and induced phosphorylation of p53 compared with the individual treatment. Our results demonstrate that KRGE can enhance the anticancer activity of IM and may have a substantial potential in the treatment of CML. Copyright

Ethanolic Hwaeumjeon induces mitochondrial dependent apoptosis partly via PI3K/AKT/HSP27/ERK pathways and inhibits PSA and AR in LNCaP cells.

Hwaeumjeon is a classical prescription that has been traditionally used for treatment of urogenital diseases with no scientific evidences until now. Thus, the present study was performed to evaluate antitumor mechanism of ethanolic Hwaeumjeon (EHEJ). 2-Dimensional electrophoresis (2-DE) proteomic analysis, cell culture study, and Western blotting on apoptosis and prostate-specific antigen (PSA) related proteins were carried out in LNCaP prostate cancer cells. Eight spots with significant increased or decreased expression revealed by 2-DE based comparative proteomic analysis were identified as an increased protein ENC-1AS, four decreased proteins such as RAB34, SFRS1, heat shock 27, and proteasome activator, and three novel proteins such as Rho GDP dissociation inhibitor alpha, cytoplasmic antiproteinase, and EIF3EIP protein in EHEJ-treated LNCaP cells. In addition, EHEJ selectively inhibited the growth of LNCaP prostate cancer cells compared to normal human umbilical vein endothelial cells. Furthermore, EHEJ inhibited PSA and androgen receptor (AR) expression in androgen sensitive LNCaP prostate cancer cells at nontoxic concentrations. Also, EHEJ increased sub-G1 apoptotic portion, activated caspase-9 and -3, cleaved poly (ADP-ribose) polymerase (PARP) and increased the ratio of Bax to Bcl-2. Interestingly, EHEJ also attenuated phosphatidylinositol-3 kinase (PI3K) expression and suppressed the phosphorylation of survival gene AKT, ERK, and HSP27 in LNCaP cells. Consistently, PI3K and ERK inhibitors potentiated EHEJ-induced cytotoxicity and overexpression of Bcl-2 attenuated EHEJ-mediated apoptosis in LNCaP cells. These findings suggest that EHEJ induces mitochondrial dependent apoptosis partly via PI3K/AKT/HSP27/ERK pathways and inhibits PSA and AR in LNCaP cells as a prostate cancer chemopreventive candidate.