Human SMG-1 is involved in gemcitabine-induced primary microRNA-155/BIC up-regulation in human pancreatic cancer PANC-1 cells.
OBJECTIVE
Human primary microRNA-155/B-cell integration cluster (BIC) transcript is the precursor of microRNA-155. The overexpression of them has been widely observed in the progression of various types of tumors. Our objective was to investigate the effect of anticancer agents on the expression of BIC and possible signal pathways that involved in.


METHODS
Quantitative real-time reverse transcriptase polymerase chain reaction was used to measure the expression of BIC. Chemical inhibitors against c-Jun N-terminal kinase 1, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2, protein kinase C, checkpoint kinase 1, and phosphatidylinositol 3 kinase (PI3K) were used for the evaluation of involved signal pathways. RNA interference was used to knock down the expression of ataxia-telangiectasia mutated, ataxia-telangiectasia and Rad3 related, and suppressor of morphogenesis in genitalia-1 (SMG-1), and Western blot was carried out to evaluate the knockdown effect.


RESULTS
B-cell integration cluster expression was induced by a representative anti-pancreatic cancer drug, gemcitabine, in human pancreatic cancer PANC-1 cells. The mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 and c-Jun N-terminal kinase inhibitors, but not the checkpoint kinase 1 and protein kinase C inhibitors, suppressed the up-regulation of BIC. B-cell integration cluster up-regulation was also significantly inhibited by the PI3K inhibitor wortmannin. RNA interference studies showed that wortmannin-sensitive SMG-1 but not ataxia-telangiectasia mutated or ataxia-telangiectasia and Rad3 related was involved in the up-regulation.


CONCLUSIONS
Our results show that multiple pathways can be involved in the up-regulation of BIC. Furthermore, we demonstrate for the first time that PI3K SMG-1 is required for gemcitabine-induced up-regulation of BIC transcript.
Xia
Qi-sheng
QS
Department of Medical Oncology, Kanazawa Medical University, Uchinada, Ishikawa, Japan.
Ishigaki
Yasuhito
Y
Zhao
Xia
X
Shimasaki
Takeo
T
Nakajima
Hideo
H
Nakagawa
Hideaki
H
Takegami
Tsutomu
T
Chen
Zhi-hua
ZH
Motoo
Yoshiharu
Y
D000730:Androstadienes / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000502:physiology; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000502:physiology; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology; D035683:MicroRNAs / Q000235:genetics*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D025521:Tumor Suppressor Proteins / Q000502:physiology; D015854:Up-Regulation; D000077191:Wortmannin; D000093542:Gemcitabine
D000730:Androstadienes; D000964:Antimetabolites, Antineoplastic; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D003841:Deoxycytidine; D048049:Extracellular Signal-Regulated MAP Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D035683:MicroRNAs; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D025521:Tumor Suppressor Proteins; D000077191:Wortmannin; D000093542:Gemcitabine; C524942:MIRN155 microRNA, human; C576324:ATM protein, human; C576597:ATR protein, human; C514704:SMG1 protein, human