pERK1/2 silencing sensitizes pancreatic cancer BXPC-3 cell to gemcitabine-induced apoptosis via regulating Bax and Bcl-2 expression.

BACKGROUND: Our previous study has demonstrated that knockdown of activated ERK1/2(pERK1/2) sensitizes pancreatic cancer cells to chemotherapeutic drug gemcitabine (Gem) treatment. However, the details of this survival mechanism remain undefined. It has also shown that Bcl-2 confers resistance and Bax sensitizes to gemcitabine-induced apoptosis in pancreatic cancer cells. Furthermore, the extracellular signaling-regulated kinase (ERK) signaling pathway regulates Bcl-2/Bax expression ratio. We therefore tested the hypothesis that pancreatic cancer cells are resistant to gemcitabine and this resistance is due to activation of ERK1/2 and subsequent upregulation of Bcl-2 and downregulation of Bax. METHODS: Pancreatic cancer cell BXPC-3 was used in the study. The effect of pharmacological inhibition of ERK1/2 on resistance of pancreatic cancer cells to apoptosis induced by treatment with gemcitabine was analyzed. The following methods were utilized: TUNEL and ELISA were used to detect apoptosis. Western blot was used to detect the protein expression. RESULTS: Gemcitabine treatment enhanced the activity of ERK1/2 in the BXPC-3 cells. Inhibition of the ERK1/2 by PD98059 could downregulate Bcl-2 and upregulate Bax and was associated with restoration of sensitivity to gemcitabine in BXPC-3 cells. Depletion of endogenous Bcl-2 expression by specific small interfering RNA transfection significantly increased gemcitabine-induced cell apoptosis. Combined treatment with PD98059 and Bax siRNA transfection could decrease gemcitabine-induced ERK1/2 and Bax activation, which subsequently resulted in decreased apoptosis. CONCLUSIONS: The upregulation of ERK1/2-dependent Bcl-2 and downregulation of ERK1/2-dependent Bax can protect human pancreatic cancer cells from gemcitabine-induced apoptosis. Targeting the ERK1/2-Bax/Bcl-2 pathway may in part lead to sensitization of pancreatic cancer to gemcitabine.

Serum miR-542-3p as a prognostic biomarker in osteosarcoma.

OBJECTIVE: Emerging evidence has suggested that circulating microRNAs (miRNAs) in body fluids have novel diagnostic and prognostic significance for patients with malignant diseases. The lack of useful biomarkers is a crucial problem of osteosarcoma (OS); Previous study has reported that miR-542-3p was significantly upregulated in osteosarcoma tissues and miR-542-3p may be as an oncogene in osteosarcoma pathogenesis. In our study, we investigated the circulating miR-542-3p and its clinical relevance in osteosarcoma. METHODS: Serum MiR-542-3p levels were determined by quantitative real-time PCR assays (qRT-PCR) in 76 patients with OS and 76 healthy volunteers. Patient survival analyses were performed by Kaplan-Meier analyses and Cox regression models. All statistical tests were two-sided. RESULTS: It was observed that the serum levels of miR-542-3p was significantly higher in patients with OS compared with the control groups (P< 0.01). High serum of miR-542-3p was significantly associated with advanced tumor stage and shorter survival (P< 0.01). ROC curve analysis calculated the ideal miR-542-3p cut-off value of 0.84 in prediction of OS, with a sensitivity of 53.8%, specificity of 93.6%, positive predictive value of 87.3% and negative predictive value of 63.7%. CONCLUSIONS: The results showed that serum miR-542-3p levels could serve as a non-invasive blood biomarker for tumor monitoring and prognostic prediction in osteosarcoma patients.

Propofol induces apoptosis of breast cancer cells by downregulation of miR-24 signal pathway.

BACKGROUND AND OBJECTIVE: Propofol, an intravenous anesthetic agent, has been found to inhibit growth of breast cancer cells. However, the mechanisms underlying the antitumor are not known. A recent report has found that propofol could significantly downregulate miR-24 expression in the human malignant cancers. In breast cancer cells, overexpression of miR-24 promotes cell proliferation and inhibits cell apoptosis by downregulation of p27. The miR-24 has been reported to be overexpressed in breast cancer and breast cancer cell lines. In the present study, we hypothesized that propofol induces apoptosis of breast cancer cells by miR-24/p27 signal pathway. METHODS: Breast cancer MDA-MB-435 cells were exposed to propofol (10 µM) for 6 hr and cell death was assessed using TUNEL staining, Flow cytometry and cleaved caspase-3 expression. microRNA-24 (miR-24) expression was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). miR-24 was overexpressed using a miR-24 mimic. P27 was knocked down using a small interfering RNA. p27 and cleaved caspase-3 expression was assessed by Western blot. RESULTS: MDA-MB-435 exposed to propofol showed a significant increase in apoptotic cells, followed by the downregulation of miR-24, upregulation of p27 expression and cleaved caspase-3 expression. Targeting p27 inhibits propofol-induced cell apoptosis; miR-24 overexpression decreased propofol-induced cell apoptosis, cleaved caspase-3 and p27 expression. CONCLUSIONS: Propofol inducescell death in MDA-MB-435 cells via inactivation of miR-24/p27 signal pathway.

Decreased expression of MUC1 induces apoptosis and inhibits migration in pancreatic cancer PANC-1 cells via regulation of Slug pathway.

MUC1, a membrane tethered mucin glycoprotein, is overexpressed in > 60% of human pancreatic cancers (PCs), and is associated with poor prognosis and enhanced metastasis. Here, we report the effect of silencing MUC1 expression on the growth, migration and invasive ability of pancreatic cancer cells, and explored its mechanisms. We observed that siRNA mediated suppression of the MUC1 expression significantly reduced invasive and migrative capability and induced apoptosis of the pancreatic cancer PANC-1 cells. We found that Slug was inhibited in the MUC1 siRNA transfected PANC-1 cells (MUC1 siRNA/PANC-1 cells). Expression of PUMA and E-cadherin was increased in the MUC1 siRNA/PANC-1 cells. PANC-1 cells overexpressing full long Slug gene (when transfected with Slug cDNA plasmid) significantly inhibited PUMA and E-cadherin expression in the MUC1 siRNA/PANC-1 cells. Silencing PUMA expression inhibited apoptosis in the MUC1 siRNA transfected PANC-1 cells (MUC1 siRNA/PANC-1 cells). Silencing E-cadherin expression restored the invasion and migration ability in the MUC1 siRNA/PANC-1 cells. We therefore concluded that silencing MUC1 expression inhibited migration and invasion, and induced apoptosis of PANC-1 cells via downregulation of Slug and upregulation of Slug dependent PUMA and E-cadherin expression. MUC1 could serve as a potential therapeutic target in pancreatic cancer.

Propofol-induced neurotoxicity in hESCs involved in activation of miR-206/PUMA signal pathway.

BACKGROUND AND OBJECTIVE: Studies in developing animals have demonstrated that when anesthetic agents, such as propofol, are early administered in life, it can lead to neuronal cell death and learning disabilities. However, the mechanisms causing these effects remains unknown. A recent report found that propofol could significantly upregulat miR-206 expression in the human ASCs. miR-206 could also induce apoptosis in human malignant cancers. Therefore, in this study, we hypothesized that propofol induces neurotoxicity in human embryonic stem cells (hESCs). METHODS: hESCs were exposed to propofol (50 µM) for 6 hr and cell death was assessed using TUNEL staining, and cleaved caspase-3 expression. miR-206 was knocked down using antagomir. PUMA was knocked down using a small interfering RNA. microRNA-206 (miR-206) expression was assessed using quantitative reverse transcription polymerase chain reaction (qRT-PCR). PUMA protein expression was detected using western blot assay. RESULTS: hESCs exposed to propofol showed a significant increase in TUNEL positive cells and cleaved caspase-3 expression, followed by the upregulation of miR-206 and PUMA expression. Targeting PUMA inhibits propofol-induced cell apoptosis; miR-206 knockdown decreased propofol-induced cell apoptosis, cleaved caspase-3 and PUMA expression. CONCLUSIONS: Propofol induce s cell death in hESC-derived neurons via activation of miR-206/PUMA signal pathway.