Lysophosphatidic acid induced nuclear translocation of nuclear factor-kappaB in Panc-1 cells by mobilizing cytosolic free calcium.
OBJECTIVE
To clarify whether Lysophosphatidic acid (LPA) activates the nuclear translocation of nuclear factor-kappaB (NF-kappaB) in pancreatic cancer.


METHODS
Panc-1, a human pancreatic cancer cell line, was used throughout the study. The expression of LPA receptors was confirmed by reverse-transcript polymerase chain reaction (RT-PCR). Cytosolic free calcium was measured by fluorescent calcium indicator fura-2, and the localization of NF-kappaB was visualized by immunofluorescent method with or without various agents, which effect cell signaling.


RESULTS
Panc-1 expressed LPA receptors, LP(A1), LP(A2) and LP(A3). LPA caused the elevation of cytosolic free calcium dose-dependently. LPA also caused the nuclear translocation of NF-kappaB. Cytosolic free calcium was attenuated by pertussis toxin (PTX) and U73122, an inhibitor of phospholipase C. The translocation of NF-kappaB was similarly attenuated by PTX and U73122, but phorbol ester, an activator of protein kinase C, alone did not translocate NF-kappaB. Furthermore, the translocation of NF-kappaB was completely blocked by Ca(2+) chelator BAPTA-AM. Thapsigargin, an endoplasmic-reticulum Ca(2+)-ATPase pump inhibitor, also promoted the translocation of NF-kappaB. Staurosporine, a protein kinase C inhibitor, attenuated translocation of NF-kappaB induced by LPA.


CONCLUSIONS
These findings suggest that protein kinase C is activated endogenously in Panc-1, and protein kinase C is essential for activating NF-kappaB with cytosolic calcium and that LPA induces the nuclear translocation of NF-kappaB in Panc-1 by mobilizing cytosolic free calcium.
Arita
Yoshiyuki
Y
Department of Medicine and Bioregulatory Science, Kyushu University, Fukuoka 812-8582, Japan.
Ito
Tetsuhide
T
Oono
Takamasa
T
Kawabe
Ken
K
Hisano
Terumasa
T
Takayanagi
Ryoichi
R
D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008246:Lysophospholipids / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D049368:Receptors, Lysophosphatidic Acid / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism
D008246:Lysophospholipids; D016328:NF-kappa B; D012333:RNA, Messenger; D049368:Receptors, Lysophosphatidic Acid; D011493:Protein Kinase C; D010738:Type C Phospholipases; C032881:lysophosphatidic acid; D002118:Calcium