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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Apoptosis, Blotting, Western, Caspase 3, Cell Cycle, Cell Line, Tumor, Cell Proliferation, Flow Cytometry, Gene Expression Regulation, Enzymologic, Gene Expression Regulation, Neoplastic, Humans, Hyperthermia, Induced, Immunohistochemistry, JNK Mitogen-Activated Protein Kinases, Reverse Transcriptase Polymerase Chain Reaction, Stomach Neoplasms, Time Factors, bcl-2-Associated X Protein.
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Is c-Jun N-terminal kinase required for thermotherapy-induced apoptosis in human gastric cancer cells? Context: To investigate the role of c-Jun N-terminal kinase (JNK) in thermotherapy-induced apoptosis in human gastric cancer SGC-7901 cells. Human gastric cancer SGC-7901 cells were cultured in vitro. Following thermotherapy at 43°C for 0, 0.5, 1, 2 or 3 h, the cells were cultured for a further 24 h with or without the JNK specific inhibitor, SP600125 for 2 h. Apoptosis was evaluated by immunohistochemistry [terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)] and flow cytometry (Annexin vs propidium iodide). Cell proliferation was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The production of p-JNK, Bcl-2, Bax and caspase-3 proteins was evaluated by Western blotting. The expression of JNK at mRNA level was determined by reverse transcription polymerase chain reaction. The proliferation of gastric carcinoma SGC-7901 cells was significantly inhibited following thermotherapy, and was 32.7%, 30.6%, 43.8% and 52.9% at 0.5, 1, 2 and 3 h post-thermotherapy, respectively. Flow cytometry analysis revealed an increased population of SGC-790l cells in G0/G1 phase, but a reduced population in S phase following thermotherapy for 1 or 2 h, compared to untreated cells (P < 0.05). The increased number of SGC-790l cells in G0/G1 phase was consistent with induced apoptosis (flow cytometry) following thermotherapy for 0.5, 1, 2 or 3 h, compared to the untreated group (46.5% ± 0.23%, 39.9% ± 0.53%, 56.6% ± 0.35% and 50.4% ± 0.29% vs 7.3% ± 0.10%, P < 0.01), respectively. This was supported by the TUNEL assay (48.2% ± 0.4%, 40.1% ± 0.2%, 61.2% ± 0.29% and 52.0% ± 0.42% vs 12.2% ± 0.22%, P < 0.01) respectively. More importantly, the expression of p-JNK protein and JNK mRNA levels were significantly higher at 0.5 h than at 0 h post-treatment (P < 0.01), and peaked at 2 h. A similar pattern was detected for Bax and caspase-3 proteins. Bcl-2 increased at 0.5 h, peaked at 1 h, and then decreased. Furthermore, the JNK specific inhibitor, SP600125, suppressed p-JNK, Bax and caspase-3 at the protein level in SGC790l cells following thermotherapy, compared to mock-inhibitor treatment, which was in line with the decreased rate of apoptosis. The expression of Bcl-2 was consistent with thermotherapy alone.
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Thermotherapy induced apoptosis in gastric cancer cells by promoting p-JNK at the mRNA and protein levels, and up-regulated the expression of Bax and caspase-3 proteins. Bcl-2 may play a protective role during thermotherapy. Activation of JNK via the Bax-caspase-3 pathway may be important in thermotherapy-induced apoptosis in gastric cancer cells. Final Decision: yes