丹参酮ⅡA介导p38MAPK信号转导诱导人肝癌细胞凋亡

Bufalin induces apoptosis of pancreatic cancer cells via the JNK signaling pathway

AIM: To investigate whether bufalin induces apoptosis of human pancreatic cancer cells via the JNK signaling pathway.

METHODS: The cytostatic effect of bufalin on human pancreatic cancer cell line BxPC-3 was evaluated by MTT assay. The impact of bufalin on apoptosis and p-JNK expression was determined by flow cytometry (FCM) and Western blot, respectively. The mRNA expression level of survivin was detected by fluorescent quantitative PCR in BxPC-3 cells treated with bufalin in the absence or presence of a JNK inhibitor.

RESULTS: Bufalin inhibited cell growth in a concentration- and time-dependent manner. BxPC-3 cells treated with 0.16, 0.32, or 0.64 mg/L of bufalin for 48 h had cell apoptotic rates of 19.36% ± 0.39%, 40.69% ± 0.44% and 59.63% ± 1.14%, respectively, showing a significant difference among the three groups (P < 0.01). After the JNK signaling pathway was blocked, cell apoptotic rate decreased significantly (P < 0.01).After bufalin treatment, p-JNK expression was up-regulated at 1 h and reached the peak at 2 h. The mRNA expression of survivin decreased obviously after treatment with 0.32 mg/L of bufalin for 48 h, but increased significantly when the NK signaling pathway was blocked.

CONCLUSION: Bufalin can induce apoptosis of human pancreatic cancer cells. The anti-pancreatic cancer activity of bufalin might involve down-regulation of survivin mRNA via the SAPK/JNK signal transduction pathway.

Tanshinone IIA induces apoptosis of pancreatic cancer cells via the SAPK/JNK signal pathway

AIM: To investigate whether tanshinone IIA (TSIIA) induces apoptosis of human pancreatic cancer cells via the SAPK/JNK signal pathway.

METHODS: After treatment with TSIIA, MTT assay was used to observe the cytostatic effect of TSIIA on human pancreatic cancer PANC-1 cells; cell apoptosis was assessed by immunofluorescence and flow cytometry (FCM); p-JNK expression was assayed by Western blot; and mRNA expression of survivin was detected by quantitative fluorescence PCR.

RESULTS: TSIIA inhibited PANC-1 cell growth in a concentration- and time-dependent manner. After PANC-1 cells were treated with 8, 16, or 32 mg/L of TSIIA for 48 h, typical morphologic changes of apoptosis were observed by fluorescence microscopy after Hoechst staining. The apoptosis rates of cells treated with 8, 16, and 32 mg/L of TSIIA for 48 h were (8.83 ± 1.51)%, (12.86 ± 2.70)% and (21.24 ± 2.58)%, respectively, showing a significant difference among the three groups (P < 0.01). After the SAPK/JNK signal pathway was blocked, cell apoptosis rate decreased significantly (P < 0.01). p-JNK expression began to increase at 1 h and reached the peak at 4 h after TSIIA treatment. The mRNA expression of the survivin gene decreased obviously after treatment with 16 mg/L TSIIA for 48 h but increased significantly when the SAPK/JNK signal transduction pathway was blocked.

CONCLUSION: TSIIA can induce human pancreatic cancer cell apoptosis. TSIIA exerts anti-pancreatic cancer effects possibly by down-regulating the expression of survivin mRNA via the SAPK/JNK signal transduction pathway.

Helicobacter pylori infection increases the transcriptional activity of COX-2 promoter via the p38MAPK signal transduction pathway in MKN45 cells

AIM: To investigate the effect of Helicobacter pylori (H.pylori) infection on the transcriptional activity of cyclooxygenase-2 (COX-2) promoter in gastric cancer MKN45 cells and to explore potential mechanisms involved.

METHODS: The recombinant vector pGL3-Basic-COX-2-promoter and a control vector (pRL-SV40) was transiently co-transfected into MKN45 cells. Twelve hours later, the transfected cells were infected with H.pylori (100 times the number of cells) for different durations. The COX-2 promoter activity was detected using the dual luciferase assay. The activation of p38MAPK pathway was evaluated by Western blot. The p38MAPK signal transduction pathway was then blocked with a specific inhibitor SB203580 to detect the effect of H.pylori infection on COX-2 promoter activity.

RESULTS: After transient transfection, the activity of COX-2 promoter in MKN45 cells was increased with time. At 40 h after transfection, the activity of dual-luciferase was 3.5 folds higher than that at 8 h (P < 0.05). H.pylori infection significantly increased the activity of dual-luciferase compared with control cells (all P < 0.05 or 0.01). The activity of dual-luciferase in cells infected with H.pylori at 40 h after transfection was 5 folds higher than that at 8 h (P < 0.01). The expression of p38MAPK was up-regulated at 20 min after infection and reached the peak at 60 min. Blockage of the p38MAPK signal transduction pathway with SB203580 significantly reduced the COX-2 promoter activity.

CONCLUSION: H.pylori infection increases the transcriptional activity of COX-2 promoter via the p38MAPK signal transduction pathway, which may be one of the important mechanisms by which H.pylori infection causes gastric cancer.

Effects of combined Tan IIA and 5-FU on cell proliferation, apoptosis, and the expression of HIF-1α and mutant P53 in human gastric cancer cell line SGC7901 under hypoxia

AIM: To investigate the effects of combined tanshinone IIA (Tan IIA) and 5-fluorouracil (5-FU) on cell proliferation, apoptosis, and the expressions of hypoxia-inducible factor-1 alpha (HIF-1α) and mutant P53 (mt P53) in human gastric cancer cell line SGC7901 under hypoxia.

METHODS: Hypoxia was induced in SGC7901 cells by cobalt dichloride treatment. SGC7901 cells under hypoxia were treated with different concentrations of Tan IIA in combination with 10.0 mg/L of 5-FU for 24, 48 and 72 hours. Cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) assay. Cell apoptosis was detected by Hoechst staining. The expression of HIF-1α and mt P53 proteins was detected by immunocytochemistry.

RESULTS: Combined Tan IIA and 5-FU significantly inhibited the proliferation of SGC7901 cells (all P < 0.01) in a dose- and time-dependent manner under hypoxia. The reduced proliferation rate of cells incubated with Tan IIA at a concentration of 10 mg/L and 5-FU for 72 hours was 67.46%. Hoechst staining showed that Tan IIA in combination with 5-FU promoted the apoptosis of SGC7901 cells in a dose- and time-dependent manner under hypoxia (all P < 0.01). Immunocytochemical staining revealed that the expression levels of HIF-1α and mt P53 proteins in SGC7901 cells under hypoxia were evidently higher than those in SGC7901 cells under normal conditions (t = 22.786 and 13.914, respectively; both P < 0.01). However, Tan IIA in combination with 5-FU significantly downregulated the expression of HIF-1α and mt P53 proteins in SGC7901 cells under hypoxia (F = 182.234 and 130.062, respectively; both P < 0.01). A significant positive correlation was noted between the expression of HIF-1α and mt P53 in SGC7901 cells (n = 5, r = 0.995, P < 0.01).

CONCLUSION: Tan IIA can significantly enhance 5-FU-mediated growth inhibition and apoptosis induction in SGC7901 cells under hypoxia perhaps by downregulating HIF-1α and mt P53 protein expression.