Biomedical subjects

Yung-Jue Bang

Publications and source records attributed to Yung-Jue Bang.

At least 19 recordsLinked to original sources

PubMed2006

Clinical predictors versus epidermal growth factor receptor mutation in gefitinib-treated non-small-cell lung cancer patients.

BACKGROUND: Clinical predictors including Asian, female, adenocarcinoma and never-smoker and epidermal growth factor mutation are associated with gefitinib responsiveness in non-small-cell lung cancer. Direct comparison between clinical predictors and EGFR mutation for their predictive power has not been reported. PATIENTS AND METHODS: For 120 Korean NSCLC patients treated with gefitinib, we have analyzed EGFR mutational status in exons 18, 19 and 21. Patients were grouped according to the number of clinical predictors (female, adenocarcinoma and never-smoker). Response rate (RR), time-to-progression (TTP) and overall survival (OS) were analyzed. Multivariate analysis was performed to investigate which approach yielded better prediction. RESULTS: RRs according to number of clinical predictors were 0: 3.4%, 1: 17.1%, 2: 29.4% and 3: 33.3% (p=0.002). Patients with gefitinib-sensitive EGFR mutation showed 61.9% RR compared with 12.1% in the remaining patients (p<0.001). RRs were higher in patients with the EGFR mutations regardless of the number of clinical predictors. In multivariate analysis, gefitinib-sensitive EGFR mutation showed higher odds ratio of response (9.6, 95% confidence interval [CI] 3.2-28.7) compared with number of clinical predictors (1.7, 95% CI 1.1-2.7). Hazard ratio (HR) of TTP was also better in gefitinib-sensitive EGFR mutation (0.24, 95% CI 0.12-0.47) than number of clinical predictors (0.83, 95% CI 0.69-0.99). Only gefitinib-sensitive EGFR mutation was associated with improved OS (HR 0.25, 95% CI 0.12-0.52). CONCLUSION: EGFR mutation should be analyzed whenever possible for effective prediction of objective benefit from gefitinib in NSCLC patients with one or more clinical predictors.

Adenocarcinoma↗

PubMed2006

High fluorodeoxyglucose uptake on positron emission tomography in patients with advanced non-small cell lung cancer on platinum-based combination chemotherapy.

PURPOSE: To evaluate response and survival for platinum-based combination chemotherapy in chemonaive patients with non-small cell lung cancer (NSCLC) according to pretreatment standardized uptake values (SUV) by fluorodeoxyglucose positron emission tomography. EXPERIMENTAL DESIGN: Patients with advanced NSCLC who had not previously received chemotherapy were eligible. Response rates and survivals were analyzed according to maximal SUVs [low ( 7.5), where 7.5 was the median value] before the first cycle of chemotherapy. RESULTS: Eighty-five consecutive patients were included in the retrospective study. Patients with high SUV tumors exhibited significantly higher response rates (34.1% for low SUVs versus 61.0% for high SUVs; P = 0.013). Other factors, including sex, age, histology, performance status, number of involved organs, regimens used, and disease stage, did not affect response. However, high SUVs were related with a shorter response duration (279 days for low SUVs versus 141 days for high SUVs; P = 0.003) and time to progression (282 days for low SUVs versus 169 days for high SUVs; P = 0.015). Overall survival was unaffected by maximal SUVs (623 days for low SUVs versus 464 days for high SUVs; P = 0.431). CONCLUSIONS: Patients having NSCLC with high maximal SUVs showed a better response to platinum-based combination chemotherapy but had a shorter time to progression. Tumor glucose metabolism, as determined by SUVs on fluorodeoxyglucose positron emission tomography, was found to discriminate NSCLC subsets with different clinical and biological features.

Aged↗

PubMed2006

Optimization of patient selection for gefitinib in non-small cell lung cancer by combined analysis of epidermal growth factor receptor mutation, K-ras mutation, and Akt phosphorylation.

PURPOSE: Mutations in epidermal growth factor receptor (EGFR) are strongly predictive of gefitinib efficacy in non-small-cell lung cancer. However, the presence of EGFR mutant nonresponses and nonmutant responses points out the need for more comprehensive analysis. PATIENTS AND METHODS: For 69 non-small-cell lung cancer patients treated with gefitinib, we have extended our analysis to EGFR gene copy number by fluorescence in situ hybridization, mutations in K-ras, HER2, and exon 20 of EGFR by direct sequencing, and phosphatase and tensin homologue expression by immunohistochemistry, in addition to EGFR exons 18, 19, and 21, and phosphorylations of Akt and extracellular signal-regulated kinase reported previously. RESULTS: EGFR mutation and high gene copy number were associated with better objective response in univariate analysis. However, only gefitinib-sensitive EGFR mutation was independently predictive of both response (P = 0.011) and survival (P = 0.002) in multivariate analysis. No patients with K-ras mutation, including two EGFR mutants, showed response. In EGFR nonmutants, patients with either K-ras mutation or p-Akt overexpression exhibited poor response and time-to-progression whereas patients with high gene copy number tended to have better outcomes in univariate analysis. In multivariate analysis of time-to-progression in EGFR nonmutants, K-ras mutation or p-Akt overexpression was associated with shorter time-to-progression (P = 0.017). No patient with HER2 mutation showed response to gefitinib. Reduced phosphatase and tensin homologue expression was not associated with gefitinib sensitivity. CONCLUSION: Gefitinib-sensitive EGFR mutation is the single most important predictor of gefitinib sensitivity. In addition to EGFR mutation, K-ras mutation and Akt phosphorylation aid in better prediction of gefitinib responsiveness in non-small-cell lung cancer.

Adult↗

PubMed2006

First-line ifosfamide, methotrexate, etoposide and prednisolone chemotherapy +/- radiotherapy is active in stage I/II extranodal NK/T-cell lymphoma.

Although most patients diagnosed with extranodal NK/T-cell lymphoma (NTCL) have localized disease, radiotherapy alone is unsatisfactory because of frequent systemic failure and conventional doxorubicin-based chemotherapy has low efficacy. Twenty-six patients with NTCL received ifosfamide, methotrexate, etoposide and prednisolone (IMEP) chemotherapy as first-line treatment [ifosfamide 1.5 g/m2 (days 1 - 3), methotrexate 30 mg/m2 (days 3 and 10), etoposide 100 mg/m2 (days 1 - 3) and prednisolone 120 mg (days 1 - 5)]. Radiotherapy was administered only to patients with Ann Arbor stage I/II that had not achieved complete remission (CR) or to those that developed local failure after completing chemotherapy. Sixteen patients (group A) had nasal or upper aerodigestive tract localization (stage I/II) and 10 (group B) had extranasal or disseminated disease. Of the 14 evaluable patients in group A, 11 (79%) achieved CR after IMEP alone and 13 (93%) after chemotherapy +/- additional radiotherapy. Although, out of the 11 patients who achieved CR with chemotherapy alone, seven developed recurrence, all recurrences were local failure and successfully treated by additional curative radiotherapy. However, patients in group B responded poorly (CR 13%). IMEP regimen was active in NTCL patients with nasal or upper aerodigestive tract localization. Considering local failure rate after IMEP alone, initial IMEP chemotherapy followed by radiotherapy may be a promising treatment strategy in this subset of NTCL.

Adult↗

PubMed2006

Epidermal growth factor receptor mutations and response to chemotherapy in patients with non-small-cell lung cancer.

BACKGROUND: The association of epidermal growth factor receptor (EGFR) mutations with the response to conventional cytotoxic chemotherapeutic agents in non-small-cell lung cancer patients has not been investigated. We retrospectively analyzed the associations between response to chemotherapy and molecular markers associated with gefitinib responsiveness including EGFR mutations. METHODS: EGFR (exons 18, 19 and 21) and K-ras mutations (exon 2) were studied by direct sequencing and p-Erk and p-Akt expressions were studied by immunohistochemistry in archival paraffin embedded tissues. Response rate (RR) and time-to-progression (TTP) of prior chemotherapy by platinum, paclitaxel and gemcitabine were analyzed with respect to the presence of EGFR and K-ras mutations, and p-Erk and p-Akt expressions. RESULTS: Of 90 patients investigated, 75 received platinums and 45 received paclitaxel as first-line chemotherapy agents. The RRS and TTPS of platinum- and paclitaxel-containing regimens were not affected by EGFR or K-ras mutations, nor by p-Erk or p-Akt expression. Fifty-seven patients received gemcitabine as first- or second-line chemotherapy. RR was not affected by EGFR or K-ras mutations or by p-Akt expression. However, all responders to gemcitabine exhibited (+) p-Erk expression [RR 30.6% for p-Erk (+) versus 0% for p-Erk (-), P = 0.01]. TTP was not affected by EGFR or K-ras mutations or by p-Erk or p-Akt expression. CONCLUSIONS: EGFR mutations did not affect response to conventional chemotherapeutic agents, namely platinums, paclitaxel and gemcitabine. Our results also suggest that it may be undesirable to use gemcitabine in patients with tumors not expressing p-Erk.

Antineoplastic Agents↗

PubMed2006

Histone deacetylase inhibitor enhances 5-fluorouracil cytotoxicity by down-regulating thymidylate synthase in human cancer cells.

Thymidylate synthase (TS) overexpression is a key determinant of 5-fluorouracil (5-FU) resistance in human cancer cells. TS is also acutely up-regulated with 5-FU treatment, and, thus, novel strategies targeting TS down-regulation seem to be promising in terms of modulating 5-FU resistance. Here, we report that histone deacetylase inhibitors can reverse 5-FU resistance by down-regulating TS. By using cDNA microarrays and validation experiments, we found that trichostatin A reduced the expression of both TS mRNA and TS protein. Cotreatment with trichostatin A and cycloheximide restored TS mRNA expression, suggesting that TS mRNA is repressed through new protein synthesis. On the other hand, TS protein expression was significantly reduced by lower doses of trichostatin A (50 nmol/L). Mechanistically, TS protein was found to interact with heat shock protein (Hsp) complex, and trichostatin A treatment induced chaperonic Hsp90 acetylation and subsequently enhanced Hsp70 binding to TS, which led to the proteasomal degradation of TS protein. Of note, combined treatment with low-dose trichostatin A and 5-FU enhanced 5-FU-mediated cytotoxicity in 5-FU-resistant cancer cells in accordance with TS protein down-regulation. We conclude that a combinatorial approach using histone deacetylase inhibitors may be useful at overcoming 5-FU resistance.

Acetylation↗

PubMed2006

Primary systemic anaplastic large cell lymphoma in a single Korean institution: clinical characteristics and treatment outcome.

Despite advances in the characterization of anaplastic large cell lymphoma (ALCL), little data is available on Asian patients. We report here upon single Korean institution's experience regarding the clinical characteristics and outcomes of ALCL. We performed a retrospective study of 32 adults with ALCL. Most of the patients received anthracycline-based chemotherapy. Ann Arbor stage III-IV, B symptoms, high-intermediate/ high International Prognostic Index (IPI), and extranodal disease at diagnosis were present in 56%, 44%, 41%, and 63%, respectively. Compared with Western studies, the male/female ratio (4.3) was markedly higher and skin (9%) and bone involvement (9%) were less frequent. The staining results for anaplastic lymphoma kinase were positive in 6 (33%) of 18 cases available. The complete response (CR) rate was 62% (95% CI, 44-80%). With a median follow-up of 51.0 months, 5 yr overall survival was 40+/-11%. The 3 yr relapse-free survival for the 18 patients who achieved CR was 74+/-12%. Age, performance status, lactate dehydrogenase, extranodal disease sites number, and IPI were correlated with treatment response and survival. Our data suggest that Korean ALCL patients appear to have a higher male/female ratio, less frequent skin/bone involvement, and lower CR rate compared with those of Western studies.

Adolescent↗

PubMed2005

Inhibition of histone deacetylation blocks cardiac hypertrophy induced by angiotensin II infusion and aortic banding.

BACKGROUND: A number of distinct stress signaling pathways in myocardium cause cardiac hypertrophy and heart failure. Class II histone deacetylases (HDACs) antagonize several stress-induced pathways and hypertrophy. However, cardiac hypertrophy induced by transgenic overexpression of the homeodomain only protein, HOP, can be prevented by the nonspecific HDAC inhibitors trichostatin A and valproic acid, suggesting that alternate targets that oppose class II HDAC function might exist in myocardium. We tested the effects of several HDAC inhibitors, including a class I HDAC-selective inhibitor, SK-7041, on cardiac hypertrophy induced by angiotensin II (Ang II) treatment or aortic banding (AB). METHODS AND RESULTS: Cardiac hypertrophy was induced by chronic infusion of Ang II or by AB in mice or rats and evaluated by determining the ratio of heart weight to body weight or to tibia length, cross-sectional area, or echocardiogram. Cardiac hypertrophy induced by Ang II or AB for 2 weeks was significantly reduced by simultaneous administration of trichostatin A, valproic acid, or SK-7041. Echocardiogram revealed that exaggerated left ventricular systolic dimensions were relieved by HDAC inhibitors. HDAC inhibitors partially reversed preestablished cardiac hypertrophy and improved survival of AB mice. The expressions of atrial natriuretic factor, alpha-tubulin, beta-myosin heavy chain, and interstitial fibrosis were reduced by HDAC inhibition. CONCLUSIONS: These results suggest that the predominant effect of HDAC inhibition, mainly mediated by class I HDACs, is to prevent cardiac hypertrophy in response to a broad range of agonist and stretch stimuli.

Angiotensin II↗

PubMed2005

Phase II trial of low-dose paclitaxel and cisplatin in patients with advanced gastric cancer.

BACKGROUND: Paclitaxel has shown promising activity in gastric cancer and has synergism with cisplatin. This study was performed to evaluate the efficacy and toxicity of low-dose paclitaxel (145 mg/m(2)) plus cisplatin chemotherapy in metastatic or relapsed gastric cancer. METHODS: Chemotherapy-naïve patients with metastatic or relapsed gastric cancer were enrolled. Paclitaxel 145 mg/m(2) was administered intravenously over 3 h, followed by cisplatin 60 mg/m(2) on Day 1 every 3 weeks in the outpatient setting. RESULTS: Of 39 patients enrolled, 17 (44%) had partial responses. Twelve (31%) had stable disease and eight (21%) progressive disease. Two patients (5%) were not evaluable because of early drop-out. The median time to progression was 4.7 months and the median overall survival was 12.1 months. The most common hematologic toxicity was anemia (41%). Grade 3/4 neutropenia and thrombocytopenia developed in 14 and 3%, respectively. The most common non-hematologic toxicities were peripheral neuropathy (43%) and emesis (43%). Grade 3/4 non-hematologic toxicities included emesis (11%), peripheral neuropathy (3%), diarrhea (3%) and hepatotoxicity (3%). CONCLUSIONS: Low-dose paclitaxel and cisplatin chemotherapy was active and well-tolerated in chemotherapy-naïve gastric cancer patients. This regimen seems to have comparable efficacy to previously reported higher-dose paclitaxel plus cisplatin-containing regimens and fewer toxicities.

Adenocarcinoma↗

PubMed2005

CPR or DNR? End-of-life decision in Korean cancer patients: a single center's experience.

PURPOSE: Whether or not physicians should conduct cardiopulmonary resuscitation (CPR) in terminal cancer patients has long been debated. We conducted this prospective observational study to characterize current CPR and do-not-resuscitate (DNR) practice among terminal cancer patients in South Korea. MATERIALS AND METHODS: The study involved patients with terminal cancer who were admitted at the Seoul National University Boramae Hospital for supportive care only, and who died between January 1, 2003 and April 30, 2004. We investigated the practices relating to the DNR directive, i.e., how many days before death was the directive effective, and from whom was it obtained. RESULTS: Of the enrolled 165 patients, 97 were male with a mean age of 65. Median duration of admission to death was 24 days (range 7-207, mean 31.7). The DNR directive was implemented in 143 patients (86.7%). All discussions about DNR took place between physician and family members, except in only one case. DNR directives were enacted at a median of 8.0 days (range 0-79, mean 12.15) before death. For 18 patients, the DNR directive was formally taken on the day of admission. In contrast, 14 cases (9.8%) were agreed on the day of death, 18.8% within 48 h of death, and 46.8% (67 of 143) within 1 week before death, 62% before 10 days, and 71.3% within 2 weeks. The worse the performance status of the patient, the earlier the DNR discussion was issued. Also, the lower the economic and educational status of the family member, the earlier the DNR directive was attained. Of the 165 patients with terminal cancer, CPR was performed in 13 cases (7.9%): in seven cases (4.2%) CPR was requested by a family member, and in six cases arrest occurred before DNR discussion was issued. None of the resuscitated patients survived. CONCLUSION: In relation to DNR decisions in South Korean cancer patients, proxy decision-making is overwhelming and issuance of DNR discussion is raised at a late stage.

Aged↗

PubMed2005

Local tumor invasiveness is more predictive of survival than International Prognostic Index in stage I(E)/II(E) extranodal NK/T-cell lymphoma, nasal type.

This study was launched to determine the prognostic significance of local tumor invasiveness (LTI) in 114 patients diagnosed with stage I(E)/II(E) extranodal natural killer (NK)/T-cell lymphoma, nasal type (NTCL). LTI was defined as bony invasion or destruction or tumor invasion of the skin. Complete remission (CR), overall survival (OS), and disease-free survival (DFS) were compared between each group according to LTI, Ann Arbor stage, and International Prognostic Index (IPI). LTI was observed in 23 patients. Using multivariate analysis, factors associated with low probability of CR were the presence of LTI (P < .001), the presence of B symptoms (P = .003), and single-modality chemotherapy (P = .045). The presence of LTI (relative risk [RR] = 8.4, 95% confidence interval [CI] 3.9-17.9; P < .001) and high IPI score (RR = 2.8, 95% CI 1.2-6.8; P = .019) were also predictive of OS. The presence of LTI (RR = 7.3, 95% CI 3.2-16.5; P < .001) was an independently significant factor for reduced DFS. Ann Arbor staging system did not predict CR, OS, or DFS but IPI did have predictive power with regard to survival outcome. LTI is the most important prognostic factor in predicting low probability of CR and reduced OS and DFS in nasal stage I(E)/II(E) NTCL.

Adolescent↗

PubMed2005

The endogenous ratio of Smad2 and Smad3 influences the cytostatic function of Smad3.

Although Smad2 and Smad3, critical transcriptional mediators of transforming growth factor-beta (TGF-beta) signaling, are supposed to play a role in the TGF-beta cytostatic program, it remains unclear whether TGF-beta delivers cytostatic signals through both Smads equally or through either differentially. Here, we report that TGF-beta cytostatic signals rely on a Smad3-, but not a Smad2-, dependent pathway and that the intensity of TGF-beta cytostatic signals can be modulated by changing the endogenous ratio of Smad3 to Smad2. Depleting endogenous Smad3 by RNA interference sufficiently interfered with TGF-beta cytostatic actions in various TGF-beta-sensitive cell lines, whereas raising the relative endogenous ratio of Smad3 to Smad2, by depleting Smad2, markedly enhanced TGF-beta cytostatic response. Consistently, Smad3 activation and its transcriptional activity upon TGF-beta stimulation were facilitated in Smad2-depleted cells relative to controls. Most significantly, a single event of increasing this ratio by Smad2 depletion was sufficient to restore TGF-beta cytostatic action in cells resistant to TGF-beta. These findings suggest a new important determinant of sensitivity to TGF-beta cytostatic signaling.

Animals↗

PubMed2005

Oocyte-based screening of cytokinesis inhibitors and identification of pectenotoxin-2 that induces Bim/Bax-mediated apoptosis in p53-deficient tumors.

In this study, we demonstrate that a loss of p53 sensitizes tumor cells to actin damage. Using a novel oocyte-based screening system, we identified natural compounds that inhibit cytokinesis. Among these, pectenotoxin-2 (PTX-2), which was first identified as a cytotoxic entity in marine sponges, which depolymerizes actin filaments, was found to be highly effective and more potent to activate an intrinsic pathway of apoptosis in p53-deficient tumor cells compared to those with functional p53 both in vitro and in vivo. Other agents that depolymerize or knot actin filaments were also found to be toxic to p53-deficient tumors. In p53-deficient cells, PTX-2 triggers apoptosis through mitochondrial dysfunction, and this is followed by the release of proapoptotic factors and caspase activation. Furthermore, we observed Bax activation and Bim induction only in p53-deficient cells after PTX-2 treatment. RNA interference of either Bim or Bax resulted in the inhibition of caspases and apoptosis induced by PTX-2. However, the small interfering RNAs (SiRNA) of Bim blocked a conformational change of Bax, but Bax SiRNA did not affect Bim expression. Therefore, these results suggest that Bim triggers apoptosis by activating Bax in p53-deficient tumors upon actin damage, and that actin inhibitors may be potent chemotherapeutic agents against p53-deficient tumors.

Actins↗

PubMed2005

Docetaxel + 5-fluorouracil + cisplatin 3-day combination chemotherapy as a first-line treatment in patients with unresectable gastric cancer.

BACKGROUND: Our objective was to verify the efficacy and safety of "docetaxel + 5-fluorouracil + cisplatin" 3-day combination chemotherapy as a first-line treatment in patients with unresectable gastric cancer. METHODS: Between January and November 2002, we enrolled 43 patients [males 31; median age 55 years (range 24-74)] with inoperable gastric cancer who had not been seen previously in Seoul National University Hospital. The regimen used was docetaxel 70 mg/m(2) on day 1, cisplatin 40 mg/m(2) on days 2 and 3, and 5-fluorouracil 1200 mg/m(2) over 10 h on days 1-3, every 3 weeks. RESULTS: A total of 168 cycles were administered. Mean cycle number per patient was 3.9. The administered dose intensity of docetaxel was 21.23 mg/m(2)/week, 5-FU 1092.14 mg/m(2)/week and cisplatin 23.82 mg/m(2)/week, which corresponded to 91.1, 91.0 and 89.5% of planned doses. Of the 43 patients, response evaluation was possible in 40 and, of these patients, 17 (42.5%) achieved a partial response, 13 (32.5%) stable disease, and 10 patients (25%) showed progressive disease. The median time to progression was 5.6 months [95% confidence interval (CI) 4.6-6.6 months]. Median overall survival was 9.0 months. (95% CI 4.8-13.2 months). Leukopenia occurred during 21.4% of cycles (36 of 168 cycles); 14.3% grade 1, 5.3% grade 2 and 1.8% grade 3. Anemia occurred in 16.7% (28 of 168 cycles); 11.3% grade 1, 4.8% grade 2 and 0.6% grade 3. Thrombocytopenia was not observed. Diarrhea, stomatitis and hypersensitivity occurred in 4.7% (two out of 43 patients), respectively. Neutropenic fever occurred in two patients (4.7%) and myalgia in three (7.0%). CONCLUSION: "Docetaxel + 5-fluorouracil + cisplatin" 3-day combination chemotherapy is an active and tolerable regimen as a first-line treatment in patients with unresectable gastric cancer.

Adult↗

PubMed2005

Cell adhesion status-dependent histone acetylation is regulated through intracellular contractility-related signaling activities.

Although histone acetylation is important for epigenetic gene transcription, histone acetylation regulation by extracellular cues has rarely been evidenced. Here, we examined whether and how histone acetylation is regulated by cell adhesion-mediated signaling. Gastric carcinoma cells in suspension showed a higher histone acetylation, compared with fibronectin-adherent cells. This difference was supported by a decreased histone deacetylases activity. Furthermore, trichostatin A (TSA)-mediated histone acetylation was significantly increased only in suspended, but not in fibronectin-adherent, cells. Pharmacological inhibition of intracellular contractility-related myosin light chain kinase or RhoA-kinase (ROCK) or expression of ROCK1 small interfering RNA, dominant negative RhoA, or active Rac1 decreased basal and TSA-mediated histone H3 acetylations in suspended cells,whereas inhibition of calmodulin-dependent protein kinase II or transient overexpression of wild type myosin light chain kinase enhanced the acetylations. Meanwhile, chromatin immunoprecipitation showed higher basal and TSA-enhanced associations of ROCK1 promoter regions with Lys(9)-acetylated histone 3 in suspended cells than in fibronectin-adherent cells and expression of ROCK1 was higher and further increased by TSA treatment in suspension. In addition, phosphorylation of myosin light chain was further increased by TSA in suspension and higher in anchorage-independent cells over adherently growing cells, indicating an inverse relationship between ROCK1 expression-mediated contractility and cell adhesion abilities. Cell adhesion analysis showed that pharmacological activation of intracellular contractility-related signaling activities decreased cell adhesion abilities, whereas inhibition of them increased the adhesion. Taken together, these observations suggest that cell adhesion-related signal transduction regulates histone acetylation, presumably through a close functional linkage between intracellular contractility and histone deacetylases activity/histone acetylation.

Acetylation↗

PubMed2005

TGF-beta1-mediated activations of c-Src and Rac1 modulate levels of cyclins and p27(Kip1) CDK inhibitor in hepatoma cells replated on fibronectin.

Integrin-mediated cell adhesion transduces signals to regulate actin cytoskeleton and cell proliferation. While understanding how integrin signals cross-talk with the TGF-beta1 pathways, we observed lamellipodia formation and cyclin regulation in Hep3B cells, following TGF-beta1 treatment. To answer if integrin signaling via actin organization might regulate cell cycle progression after TGF-beta1 treatment, we analyzed cross-talk between the two receptor-mediated pathways in hepatoma cells on specific ECMs. We found that basal and TGF-beta1-mediated activation of c-Src and Rac1, expression of cyclins E and A, and suppression of p27Kip1 were significant in cells replated on fibronectin, but not in cells on collagen I, indicating a different integrin-mediated cellular response to TGF-beta1 treatment. Levels of tyrosine phosphorylation and actin-enriched lamellipodia on fibronectin were also more prominent than in cells on collagen I. Studies using pharmacological inhibitors or transient transfections revealed that the preferential TGF-beta1 effects in cells on fibronectin required c-Src family kinase activity. These observations suggest that a specific cross-talk between TGF-beta1 and fibronectin-binding integrin signal pathways leads to the activation of c-Src/Rac1/actin-organization, leading to changes in cell cycle regulator levels in hepatoma cells. Therefore, this study represents another mechanism to regulate cell cycle regulators when integrin signaling is collaborative with TGF-beta1 pathways.

Actins↗

PubMed2005

Cyclooxygenase-2 inhibits novel ginseng metabolite-mediated apoptosis.

Recently, a novel intestinal bacterial metabolite of ginseng protopanaxadiol saponins, i.e., 20-O-(beta-D-glucopyranosyl)-20(S)-protopanaxadiol (IH-901), has been reported to induce apoptosis in a variety of cancer cells. Here we show a differential effect of IH-901 on several cell types. Exposure to IH-901 for 48 hours at a supposedly subapoptotic concentration of 40 mumol/L led to both apoptotic cell death and G1 arrest in Hep3B cells, but only resulted in G1 arrest in MDA-MB-231, Hs578T, and MKN28 cells. Additionally, the treatment of MDA-MB-231, but not of Hep3B, with IH-901 up-regulated cyclooxygenase-2 (COX-2) mRNA (2 hours) and protein (6 hours), and enhanced the production of prostaglandin E2. In MDA-MB-231 cells, IH-901 induced the sustained activation of extracellular signal-regulated kinase (ERK), whereas inhibition of mitogen-activated protein/ERK kinase blocked IH-901-mediated COX-2 induction and resulted in apoptosis, suggesting the involvement of an ERK-COX-2 pathway. Combined treatment with IH-901 and nonsteroidal anti-inflammatory drugs inhibited COX-2 enzyme and induced apoptosis in MDA-MB-231 and Hs578T cells. Adenovirus-mediated COX-2 small interfering RNAs also effectively inhibited COX-2 protein expression and enhanced IH-901-mediated apoptosis without inhibiting ERK 1/2 phosphorylation, thus providing direct evidence that COX-2 is an antiapoptotic molecule. Moreover, IH-901-mediated G1 arrest resulted from an increase in p27Kip1 mRNA and protein expression followed by a decrease in CDK2 kinase activity that was concurrent with the hypophosphorylation of Rb and p130. In conclusion, IH-901 induced both G1 arrest and apoptosis, and this apoptosis could be inhibited by COX-2 induction.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Predictive and prognostic impact of epidermal growth factor receptor mutation in non-small-cell lung cancer patients treated with gefitinib.

PURPOSE: This study was undertaken to investigate the effects of epidermal growth factor receptor (EGFR) mutation and its downstream signaling on response and survival in non-small-cell lung cancer (NSCLC) patients treated with gefitinib. PATIENTS AND METHODS: For 90 consecutive NSCLC patients who had received gefitinib, EGFR mutation was analyzed by DNA sequencing of exons 18, 19, 21, and 23 in the EGFR tyrosine kinase domain. Expressions of phosphorylated (p) -Akt and p-Erk were determined via immunohistochemistry. Response rate, time to progression (TTP), and overall survival were compared between each group according to EGFR mutation, as well as p-Akt and p-Erk expression. RESULTS: Seventeen patients (18.9%; 95% CI, 10.8 to 27.0) harbored EGFR mutations. These mutations include deletions in exon 19 in seven patients, L858R in six patients, G719A in three patients, and a novel A859T in one patient. Response rate in patients with EGFR mutation was 64.7% (11 of 17 patients; 95% CI, 42.0 to 87.4), in contrast to 13.7% (10 of 73 patients; 95% CI, 5.8 to 21.6) in patients without mutation (P < .001). Moreover, these 17 patients with EGFR mutation had significantly prolonged TTP (21.7 v 1.8 months; P < .001) and overall survival (30.5 v 6.6 months; P < .001) compared with the remaining 73 patients without mutation. Although no significant correlation was detected between EGFR mutation and expressions of p-Akt or p-Erk, p-Akt overexpression was associated with prolonged TTP in patients with EGFR mutation. CONCLUSION: Our data further support the importance of EGFR mutation with regard to gefitinib sensitivity. In addition to its predictive role, EGFR mutation confers significant survival benefits on NSCLC patients treated with gefitinib.

Adult↗