期刊
CANCER BIOLOGY & THERAPY
卷 10, 期 10, 页码 1057-1067出版社
TAYLOR & FRANCIS INC
DOI: 10.4161/cbt.10.10.13373
关键词
Colon cancer; CREB; PGE(2); EP4 receptor; ERK; S100P; RNAi
类别
资金
- Arizona Cancer Center [CA95060]
- Allergan Inc.
- Lockton Endowment for Pancreatic Cancer Research
- NCI [CA023074-26]
- NIEHS [ES06694]
Background: Prostaglandin E-2 (PGE(2)) levels are frequently elevated in colorectal carcinomas. PGE(2) is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptor is most relevant. PGE(2)/EP4-receptor interaction activates CREB via the ERK/MEK pathway. However, the downstream target genes activated by this pathway remained to be investigated. Methodology/Prinicipal Findings: Here, we have identified S100P (an EF-hand calcium binding protein) as a novel downstream target. We show by realtime RT-PCR that S100P mRNA levels are elevated in 14/17 (82%) colon tumor tissues as compared to paired adjacent normal colonic tissues. S100P expression is stimulated in the presence of PGE(2) in a time dependent manner at mRNA and protein levels in colon, breast and pancreatic cancer cells. Pharmacological and RNA(i) mediated inhibition of the EP4 receptor attenuates PGE(2)-dependent S100P mRNA induction. RNA(i)-mediated knockdown of CREB inhibits endogenous S100P expression. Furthermore, using luciferase reporter analysis and EMSA we show that mutation and/or deletion of the CRE sequence within the S100P promoter abolished PGE(2)-mediated transcriptional induction. Finally, we demonstrate that RNA(i)-mediated knockdown of S100P compromised invadopodia formation, colony growth and motility of colon cancer cells. Interestingly, endogenous knock down of S100P decreases ERK expression levels, suggesting a role for ERK in regulating S100P mediated cell growth and motility. Conclusions/Significance: Together, our findings show for the first time that S100P expression is regulated by PGE(2)/EP4-receptor signaling and may participate in a feedback signaling that perpetuates tumor cell growth and migration. Therefore, our data suggest that dysregulated S100P expression resulting from aberrant PGE(2)/EP4 receptor signaling may have important consequences relevant to colon cancer pathogenesis.
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