PKCalpha-induced drug resistance in pancreatic cancer cells is associated with transforming growth factor-beta1.
BACKGROUND
Drug resistance remains a great challenge in the treatment of pancreatic cancer. The goal of this study was to determine whether TGF-beta1 is associated with drug resistance in pancreatic cancer.


METHODS
Pancreatic cancer BxPC3 cells were stably transfected with TGF-beta1 cDNA. Cellular morphology and cell cycle were determined and the suppressive subtracted hybridization (SSH) assay was performed to identify differentially expressed genes induced by TGF-beta1. Western blotting and immunohistochemistry were used to detect expression of TGF-beta1-related genes in the cells and tissue samples. After that, the cells were further treated with an anti-cancer drug (e.g., cisplatin) after pre-incubated with the recombinant TGF-beta1 plus PKCalpha inhibitor Gö6976. TGF-beta1 type II receptor, TbetaRII was also knocked down using TbetaRII siRNA to assess the effects of these drugs in the cells. Cell viability was assessed by MTT assay.


RESULTS
Overexpression of TGF-beta1 leads to a markedly increased invasion potential but a reduced growth rate in BxPC3 cells. Recombinant TGF-beta1 protein increases expression of PKCalpha in BxPC3 cells, a result that we confirmed by SSH. Moreover, TGF-beta1 reduced the sensitivity of BxPC3 cells to cisplatin treatment, and this was mediated by upregulation of PKCalpha. However, blockage of PKCalpha with Gö6976 and TbetaRII with siRNA reversed the resistance of BxPC3 cells to gemcitabine, even in the presence of TGF-beta1. Immunohistochemical data show that pancreatic cancers overexpress TGF-beta1 and P-gp relative to normal tissues. In addition, TGF-beta1 expression is associated with P-gp and membranous PKCalpha expression in pancreatic cancer.


CONCLUSIONS
TGF-beta1-induced drug resistance in pancreatic cancer cells was associated with PKCalpha expression. The PKCalpha inhibitor Gö6976 could be a promising agent to sensitize pancreatic cancer cells to chemotherapy.
Chen
Ying
Y
Department of Pathology, Changhai Hospital, Second Military Medical University, Shanghai, 200433, China.
Yu
Guanzhen
G
Yu
Danghui
D
Zhu
Minghua
M
D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007124:Immunoenzyme Techniques; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D051571:Protein Kinase C-alpha / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013382:Subtraction Technique; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000099222:betaIG-H3 Protein
D016326:Extracellular Matrix Proteins; D051571:Protein Kinase C-alpha; D017346:Protein Serine-Threonine Kinases; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein