Sphingosine kinase 1 enhances colon cancer cell proliferation and invasion by upregulating the production of MMP-2/9 and uPA via MAPK pathways.
OBJECTIVE
Sphingosine kinase (SphK) 1 is an oncogenic enzyme promoting transformation, proliferation, and survival of a number of human tumor cells. However, its effect on colon cancer cell behavior has not been fully clarified.


METHODS
SphK1 plasmid or SphK1 shRNA transfection and N,N-dimethylsphingosine (DMS) was used to regulate the expression and activity of SphK1 in colon cancer line LOVO. Cell proliferation, apoptosis, invasion, and protein expression were detected by MTT, flow cytometry, transwell chambers model, and western blot. The levels of metalloproteinases-2/9 (MMP-2/9) and urokinase plasminogen activator (uPA) were detected by ELISA.


RESULTS
Overexpression of SphK1 after plasmid transfection markedly enhanced LOVO cell viability and invasiveness and reduced cell apoptosis. In contrast, inhibition of SphK1 by DMS and shRNA significantly suppressed cell viability and invasiveness but promoted cell apoptosis. SphK1 increased the constitutive expression of extracellular signal-regulated kinase1/2 (ERK1/2) but reduced the constitutive expression of p38 mitogen-activated protein kinase (MAPK). Blocking ERK1/2 pathway inhibited the biological effects induced by overexpression of SphK1. Blocking p38 MAPK pathway reversed the effects of DMS and SphK1 shRNA. Moreover, SphK1 was required for the production of MMP-2/9 and uPA in tumor cells, which was suppressed by ERK1/2 inhibitor U0126, but enhanced by the p38 MAPK inhibitor SB203580.


CONCLUSIONS
SphK1 enhances colon cancer cell proliferation and invasiveness, meanwhile suppressing cell apoptosis. SphK1 promoting the secretion of MMP-2/9 and uPA via activation of ERK1/2 and suppression of p38 MAPK pathways maybe the molecular mechanisms for its regulation of the malignant behavior of colon cancer cell.
The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region, China. poempower@163.com
Shi-Quan
SQ
Liu
Jie-An
JA
Huang
Meng-Bin
MB
Qin
Ying-Jie
YJ
Su
Ming-Yu
MY
Lai
Hai-Xing
HX
Jiang
Guo-Du
GD
Tang
D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis* / Q000378:metabolism; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis* / Q000378:metabolism; D009361:Neoplasm Invasiveness; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D015854:Up-Regulation / Q000235:genetics*; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D000099157:Sphingosine Kinase
D048049:Extracellular Signal-Regulated MAP Kinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D017853:Phosphotransferases (Alcohol Group Acceptor); D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013110:Sphingosine; D014568:Urokinase-Type Plasminogen Activator; D000099157:Sphingosine Kinase; C061800:N,N-dimethylsphingosine