Dual regulation of MMP-2 expression by the type 1 insulin-like growth factor receptor: the phosphatidylinositol 3-kinase/Akt and Raf/ERK pathways transmit opposing signals.
The matrix metalloproteinase (MMP)-2 has been recognized as a major mediator of basement membrane degradation, angiogenesis, tumor invasion, and metastasis. The factors that regulate its expression have not, however, been fully elucidated. We previously identified the type I insulin-like growth factor (IGF-I) receptor as a regulator of MMP-2 synthesis. The objective of the present study was to investigate the signal transduction pathway(s) mediating this regulation. We show here that in Lewis lung carcinoma subline H-59 cells treated with IGF-I (10 ng/ml), the PI 3-kinase (phosphatidylinositol 3'-kinase) /protein kinase B (Akt) and C-Raf/ERK pathways were activated, and MMP-2 promoter activity, mRNA, and protein synthesis were induced. MMP-2 induction was blocked by the PI 3-kinase inhibitors LY294002 and wortmannin, by overexpression of a dominant-negative Akt or wild-type PTEN (phosphatase and tensin homologue deleted on chromosome 10), and by rapamycin. In contrast, a MEK inhibitor PD98059 failed to reduce MMP-2 promoter activation and actually increased MMP-2 mRNA and protein synthesis by up to 30%. Interestingly, suppression of PI 3-kinase signaling by a dominant-negative Akt enhanced ERK activity in cells stimulated with 10 ng/ml but not with 100 ng/ml IGF-I. Furthermore, at the higher (100 ng/ml) IGF-I concentration, C-Raf and ERK, but not PI 3-kinase activation, was enhanced, and this resulted in down-regulation of MMP-2 synthesis. This effect was reversed in cells expressing a dominant-negative ERK mutant. The results suggest that IGF-I can up-regulate MMP-2 synthesis via PI 3-kinase/Akt/mTOR (the mammalian target of rapamycin) signaling while concomitantly transmitting a negative regulatory signal via the Raf/ERK pathway. The outcome of IGF-IR (the receptor for IGF-I) activation may ultimately depend on factors, such as ligand bioavailability, that can shift the balance preferentially toward one pathway or the other.
Department of Surgery, McGill University Health Center, the Royal Victoria Hospital, Room H6.25, 687 Pine Avenue West, Montreal, Quebec, Canada H3A 1A1.
Donglei
D
Zhang
Menashe
M
Bar-Eli
Sylvain
S
Meloche
Pnina
P
Brodt
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D018827:Carcinoma, Lewis Lung / Q000378:metabolism; D045744:Cell Line, Tumor; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D005799:Genes, Dominant; D017930:Genes, Reporter; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis* / Q000235:genetics*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D051059:PTEN Phosphohydrolase; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D020123:Sirolimus / Q000378:metabolism; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000077191:Wortmannin
D000730:Androstadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D005419:Flavonoids; D009025:Morpholines; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D007334:Insulin-Like Growth Factor I; D015500:Chloramphenicol O-Acetyltransferase; D019869:Phosphatidylinositol 3-Kinases; D019908:Proto-Oncogene Proteins c-raf; D020928:Mitogen-Activated Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D051059:PTEN Phosphohydrolase; D020778:Matrix Metalloproteinase 2; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D020123:Sirolimus; D000077191:Wortmannin