STI571 reduces TRAIL-induced apoptosis in colon cancer cells: c-Abl activation by the death receptor leads to stress kinase-dependent cell death

<p>Abstract</p> <p>Background</p> <p>In an effort to achieve better cancer therapies, we elucidated the combination cancer therapy of STI571 (an inhibitor of Bcr-Abl and clinically used for chronic myelogenous leukemia) and TNF-related apoptosis-inducing ligand (TRAIL, a developing antitumor agent) in leukemia, colon, and prostate cancer cells.</p> <p>Methods</p> <p>Colon cancer (HCT116, SW480), prostate cancer (PC3, LNCaP) and leukemia (K562) cells were treated with STI571 and TRAIL. Cell viability was determined by MTT assay and sub-G1 appearance. Protein expression and kinase phosphorylation were determined by Western blotting. c-Abl and p73 activities were inhibited by target-specific small interfering (si)RNA. In vitro kinase assay of c-Abl was conducted using CRK as a substrate.</p> <p>Results</p> <p>We found that STI571 exerts opposite effects on the antitumor activity of TRAIL. It enhanced cytotoxicity in TRAIL-treated K562 leukemia cells and reduced TRAIL-induced apoptosis in HCT116 and SW480 colon cancer cells, while having no effect on PC3 and LNCaP cells. In colon and prostate cancer cells, TRAIL caused c-Abl cleavage to the active form via a caspase pathway. Interestingly, JNK and p38 MAPK inhibitors effectively blocked TRAIL-induced toxicity in the colon, but not in prostate cancer cells. Next, we found that STI571 could attenuate TRAIL-induced c-Abl, JNK and p38 activation in HCT116 cells. In addition, siRNA targeting knockdown of c-Abl and p73 also reduced TRAIL-induced cytotoxicity, rendering HCT116 cells less responsive to stress kinase activation, and masking the cytoprotective effect of STI571.</p> <p>Conclusions</p> <p>All together we demonstrate a novel mediator role of p73 in activating the stress kinases p38 and JNK in the classical apoptotic pathway of TRAIL. TRAIL via caspase-dependent action can sequentially activate c-Abl, p73, and stress kinases, which contribute to apoptosis in colon cancer cells. Through the inhibition of c-Abl-mediated apoptotic p73 signaling, STI571 reduces the antitumor activity of TRAIL in colon cancer cells. Our results raise additional concerns when developing combination cancer therapy with TRAIL and STI571 in the future.</p

GATA-1 and NF-Y cooperate to mediate erythroid-specific transcription of Gfi-1B gene

Expression of Gfi (growth factor-independence)-1B, a Gfi-1-related transcriptional repressor, is restricted to erythroid lineage cells & is essential for erythropoiesis. Wehavedeterminedthe transcription start site of the human Gfi-1B gene & located its first noncoding exon 7.82 kb upstream of the first coding exon. The genomic sequence preceding this first non-coding exon has been identified to be its erythroid-specific promoter region in K562 cells. Using gel-shift & chromatin immunoprecipitation (ChIP) assays, we have demonstrated that NF-Y & GATA-1 directly participate in transcriptional activation of the Gfi-1B gene in K562 cells. Ectopic expression of GATA-1 markedly stimulates the activity of the Gfi-1B promoter in a non-erythroid cell line U937. Interestingly, our results have indicated that this GATA-1-mediated trans-activation is dependent on NF-Y binding to the CCAAT site. Here we conclude that functional cooperation between GATA-1 & NF-Y contributes to erythroid-specific transcriptional activation of Gfi-1B promoter

A Study on the Usage Intention of Japanese Learning Mobile Applications

Mobile applications change living habits and social style and provide an alternative learning channel for foreign languages. The use of applications overcomes limitations of time and space, thus enhancing the effectiveness of foreign language learning. In Taiwan, from the university students learning a foreign language, most part is learning English, followed by Japanese. Many scholars have conducted studies on issues related to English learning applications, but few have studied Japanese learning applications. Therefore, the main purpose of this study is to investigate the factors that influence learners to use Japanese learning applications. An online questionnaire survey was conducted from February 21 to March 2, 2021, in the Japanese language group of the Department of Applied Foreign Languages at a university in northern Taiwan. From the 127 valid forms collected, 40 respondents indicated they have not used Japanese learning applications. Thus, the remaining 87 answers were analyzed using the statistical software IBM SPSS Statistics 20. The results showed that among all variables, the mean score of “perceived ease of use” was the highest and that of “behavioral intention” was the lowest. Empirical analysis revealed that “perceived usefulness,” “facilitating conditions,” and “social influence” were the key factors that influenced the “behavioral intention” of learners. The findings can provide design guidelines for Japanese learning application developers and serve as a reference for educators to promote the use of Japanese learning applications

Method of Information Technology Enhanced Japanese Vocabulary Learning and Evaluation

Japanese vocabulary proficiency is directly related to Japanese language proficiency, and the learning and evaluation of Japanese vocabulary is vital in Japanese learning. To evaluate the learners’ Japanese vocabulary proficiency, in this study, we propose an effective method for evaluating Japanese vocabulary and implement it into a system. To prove the evaluation ability of the proposed method and implemented system, we conducted an experiment involving 80 students from the Japanese Group of the department of applied foreign languages of a senior high school to investigate the effectiveness of the method and system. The results of this study confirmed that (1) the reliability and validity of the proposed Japanese vocabulary evaluation method and system are favorable; and (2) the correlation coefficient between the experimental results and the students’ academic performance is higher than 0.80. Theoretically, the multidimensional Japanese vocabulary quotient model proposed herein can be the basis for Japanese vocabulary detection. Practically, the low-cost and rapid Japanese vocabulary evaluation system developed is applicable to educational evaluation, whereas the technical evaluation method and system for Japanese vocabulary can improve the efficiency and effectiveness in evaluating the Japanese vocabulary of learners

Cytosolic Retention of Phosphorylated Extracellular Signal-Regulated Kinase and a Rho-Associated Kinase-Mediated Signal Impair Expression of p21(Cip1/Waf1) in Phorbol 12-Myristate-13- Acetate-Induced Apoptotic Cells

In response to treatment with phorbol-12-myristate-13-acetate (PMA), the half-population of erythromyeloblast D2 cells, a cytokine-independent variant of TF-1 cells, displayed adhesion and differentiated into a monocyte/macrophage-like morphology, while the other half-population remained in suspension and underwent apoptosis. Expression of the cell cycle inhibitor p21(Cip1/Waf1) was induced after PMA treatment in the adherent cells but not in the proapoptotic cells. We investigated the mechanism responsible for the impairment of p21(Cip1/Waf1) induction in PMA-induced proapoptotic cells. We demonstrated that in PMA-induced adherent cells, upregulation of p21(Cip1/Waf1) requires the activation and nuclear translocation of phosphorylated extracellular signal-regulated kinase (phospho-ERK). Although ERK was phosphorylated to comparable levels in PMA-induced proapoptotic and adherent cells, nuclear distribution of phospho-ERK was seen only in the adherent, not in the proapoptotic cells. We also found that only PMA-induced proapoptotic cells contained the phosphorylated form of myosin light chain, which is dependent on Rho-associated kinase (ROCK) activation, and that expression of a dominant-active form of ROCK suppressed activation of the p21(Cip1/Waf1) promoter during PMA induction. Finally, we demonstrated that inhibition of ROCK restores nuclear distribution of phospho-ERK and activation of p21(Cip1/Waf1) expression. Based on these findings, we propose that a ROCK-mediated signal is involved in interfering with the process of ERK-mediated p21(Cip1/Waf1) induction in PMA-induced proapoptotic TF-1 and D2 cells