title: Human placental lipid induces melanogenesis through p38 MAPK in B16F10 mouse melanoma.
abstract: Melanogenesis is one of the characteristic functional activities of melanocyte/melanoma and is regulated via mitogen-activated protein kinase (MAPK) and Akt/protein kinase B (PKB) pathways. Placental total lipid fraction (PTLF), prepared from a hydroalcoholic extract of fresh term human placenta contains sphingolipids and was recently shown to stimulate melanogenesis via up-regulation of the key enzyme tyrosinase in B16F10 mouse melanoma cells. How such lipids mediate their effects on pigmentation and tyrosinase expression is a particularly important aspect of melanogenesis. To study the signaling that leads to tyrosinase expression, we have investigated the roles of the MAPK and Akt/PKB pathways in B16F10 melanoma cells in melanogenesis in response to PTLF. Treatment of cells with PTLF led to the time dependent phosphorylation of p38 MAPK. SB203580, a p38 MAPK inhibitor, completely blocked the PTLF-induced melanogenesis by inhibiting promoter activity and subsequent expression of tyrosinase. Phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002 a blocker of the Akt signaling pathway, or an inhibitor of MEK (MAPK/ERK Kinase), PD98059 when included along with PTLF was found to potentiate PTLF-induced phosphorylation of p38 MAPK together with tyrosinase expression and melanogenesis. The results suggest that the activation of p38 MAPK plays a crucial role in PTLF-induced B16F10 melanogenesis by up-regulating tyrosinase expression.
authors.affiliation: Department of Cellular Biochemistry, Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Jadavpur, Kolkata-700 032, India.
authors.forename: Suman Kumar
authors.initials: SK
authors.lastname: Singh
authors.forename: Chinmoy
authors.initials: C
authors.lastname: Sarkar
authors.forename: Shampa
authors.initials: S
authors.lastname: Mallick
authors.forename: Bidisha
authors.initials: B
authors.lastname: Saha
authors.forename: Rabindranath
authors.initials: R
authors.lastname: Bera
authors.forename: Ranjan
authors.initials: R
authors.lastname: Bhadra
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation; D005260:Female; D006801:Humans; D008055:Lipids / Q000302:isolation & purification / Q000494:pharmacology*; D008543:Melanins / Q000096:biosynthesis*; D008545:Melanoma; D051379:Mice; D014442:Monophenol Monooxygenase / Q000096:biosynthesis*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010920:Placenta / Q000737:chemistry; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction; D014020:Tissue Extracts / Q000737:chemistry; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D008055:Lipids; D008543:Melanins; D014442:Monophenol Monooxygenase; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014020:Tissue Extracts; D048051:p38 Mitogen-Activated Protein Kinases; C494918:AKT1 protein, human