Akt1 induces extracellular matrix invasion and matrix metalloproteinase-2 activity in mouse mammary epithelial cells.
The roles of the protein-serine/threonine kinase, Akt1, in signaling pathways associated with cell motility and extracellular matrix invasion were examined in the immortalized mouse mammary epithelial cell line, COMMA-1D. COMMA-1D cells were engineered to express the avian leukosis subtype A receptor, tv-a, to permit infection by recombinant avian leukosis virus produced by the replication-competent avian splice vector, RCAS. COMMA-1D/tv-a cells transduced with RCAS/v-akt, but not RCAS/Akt1, formed anchorage-independent colonies in soft agar; however, cells overexpressing either v-akt or Akt1 became highly invasive when grown on the ECM, Matrigel. Zymography of extracellular protease activity shed into the medium by COMMA-1D/Akt1 or COMMA-1D/v-akt cells revealed elevated gelatinase activity that was confirmed to be matrix metalloproteinase-2 (MMP-2; gelatinase A) by Western blotting and immunoprecipitation-zymography. The MMP inhibitor, BB-94, blocked MMP-2 activity and invasion associated with Akt1- and v-akt-expressing cells. The proteasome inhibitor, lactacystin, markedly increased MMP-2 levels and invasion in control cells but not in Akt1- and v-akt-expressing cells. These results suggest that the invasive behavior of mammary epithelial cells induced by Akt1 is associated with increased MMP-2 expression that may result from inhibition of MMP-2 degradation by the proteasome pathway.
Park
B K
BK
Department of Pharmacology, Lombardi Cancer Center, Georgetown University School of Medicine, Washington, DC 20007, USA.
Zeng
X
X
Glazer
R I
RI
D000818:Animals; D001354:Avian Leukosis Virus / Q000235:genetics; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002471:Cell Transformation, Neoplastic / Q000378:metabolism; D004789:Enzyme Activation; D004790:Enzyme Induction; D004847:Epithelial Cells / Q000201:enzymology / Q000473:pathology; D005260:Female; D008321:Mammary Glands, Animal / Q000201:enzymology* / Q000473:pathology; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000502:physiology*; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014161:Transduction, Genetic
D011518:Proto-Oncogene Proteins; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020778:Matrix Metalloproteinase 2