| Background and ObjectivePancreatic cancer is a malignant tumor of the digestive system with high mortalityrate.To explore an effective treatment plan and improve the overall survival has been antrouble across the medicine field. Bortezomib （PS-341, trade name: Velcade）,anproteasome inhibitor, is a novel anti-tumor agent, which has been approved by the U.S.Food and Drug Administration （FDA） for the treatment of recurrent or refractorymultiple myeloma. Studies show that bortezomib also has anti-cancer activity against themajority of tumors, including small-cell lung cancer, breast cancer, prostate cancer and soon. Bortezomib as the single-agent or combined with other drugs has an promising efficacyon the inhibition of tumor growth n vivo and in vitro. Growing basic studies reveal cancercell sensitivity to bortezomib varies greatly, but researches about the molecular mechanismof bortezomib drug resistance are rarely reported.To gain insight into the mechanism ofbortezomib on growth inhibition of pancreatic caner cells and differences in pancreaticcaner cell sensitivity to bortezomib, we explore the effect of bortezomib on proliferationand apoptosis of pancreatic cancer cell lines Bxpc-3, SW1990and apoptosis-related genesexpression.Methods1. MTT assay was used to assess cell viability following the treatment with gradientconcentration of bortezomib at different time points. The appropriate duration of action andthe concentration rangeof bortezomib for further experiment was determined．2. Flow cytometry was performed to study apoptosis induced by bortezomib in twopancreatic cancer cell lines in vitro, while observing the differences between the twopancreatic cancer cells under the same conditions.3. Reverse transcription polymerase chain reaction was used to detect mRNAexpression changes of two pancreatic cancer cell, exploring the molecular pathways about antitumor activity of bortezomib and the possible mechanism associated with drugsensitivity4.Western blotting was used to detect protein expression changes of two pancreaticcancer cell, and further validate anticancer mechanism of bortezomib and its drugsensitivity-related molecules.Results1.When Bortezomib concentration was higher than50nM/L, it inhibited theproliferation of two cells in dose-dependent manner.And with the same treatment the rate of proliferation inhibition on Bxpc-3cell bybortezomib was greater than SW1990cell.2. Apoptosis rates in50,100nM/L groups of Bxpc-3and SW1990cell were（10.52±1.05）%,（22.56±4.23）%and （6.23±0.34）%,（12.71±2.23）%, which wassignificantly higher than0nM/L group [（2.15±0.47）%,（2.32±0.54）%,P all<0.05].Further more Bxpc-3cell apoptosis rate was significantly higher than SW1990cellsunder the same conditions （P <0.05）.3. Compared with the control group, no significant difference （P all>0.05）of BakmRNA among groups, the up-regulation of Bax mRNA （P all<0.05）,and thedown-regulation of Bcl-2mRNA （P all <0.05）、Bcl-Xl mRNA （P all <0.05）wasdetected after10,100nm/L bortezomib treatment in pancreatic cancer cells Bxpc-3andSW1990. Whereas Survivin mRNA was down-regulated （P <0.05） in Bxpc-3whileup-regulated （P <0.05） in SW1990.4. Compared with the control group, Caspase-3protein cleaved activation[pro-caspase-3protein expression was decreased （P all <0.05）, cleaved-caspase-3proteinexpression increased （P all <0.05）], Bax protein expression increased （P all <0.05）,Bcl-2protein expression decreased （P all <0.05） was detected after10,100nM/Lbortezomib treatment in pancreatic cancer cells Bxpc-3and SW1990. Survivin proteinBxpc-3cells was significantly decreased （P <0.05）, while with high expression ofSW1990cells （P <0.05） ConclusionsThe mechanism of bortezomib on proliferation inhibition and apoptosis of pancreaticcancer cell Iines Bxpc-3and SW1990may depand on the mitochondrial pathway ofapoptosis. While the reason why Bxpc-3is more sensitive to bortezomib than SW1990may association with the expression of Survivin after treatment of bortezomib. |
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