title: The marine natural product microsclerodermin A is a novel inhibitor of the nuclear factor kappa B and induces apoptosis in pancreatic cancer cells.
abstract: Pancreatic cancer, the 4th leading cause of cancer death in the US, is highly resistant to all current chemotherapies, and its growth is facilitated by chronic inflammation. An important mediator of inflammation is the nuclear factor kappa B (NFκB), a transcription factor that regulates over 500 genes including the regulation of anti-apoptotic proteins, cell cycle progression and cytokine production. NFκB is constitutively activated in pancreatic cancer cells contributing to their resistance to apoptosis and high metastatic potential. Although many small molecules that inhibit NFκB have been identified, none are currently used in the clinic, perhaps due to their lack of specificity. To identify novel inhibitors of NFκB, the HBOI library of enriched fractions from marine organisms was screened using a reporter cell line that produces luciferin under the transcriptional control of NFκB. Fractions from the sponge Amphibleptula were active in this screen and contained the antifungal cyclic peptide microsclerodermin A. Microsclerodermin A is shown here to inhibit NFκB transcriptional activity in a reporter cell line, to reduce levels of phosphorylated (active) NFκB in the AsPC-1 cell line, to have an IC50 for cytotoxicity in the low micromolar range against the AsPC-1, BxPC-3, MIA PaCa-2 and PANC-1 pancreatic cancer cell lines, and to induce significant apoptosis in the AsPC-1, BxPC-3 and the PANC-1 cell lines. Treatment of AsPC-1 cells with microsclerodermin A also resulted in an increase in IL-8 production without apparent induction of angiogenic factors and there is the possibility that inhibition of NFκB by microsclerodermin A is mediated by the glycogen synthase kinase 3β pathway.
authors.affiliation: Center for Marine Biomedical and Biotechnology Research, Harbor Branch Oceanographic Institute at Florida Atlantic University, 5600 US 1 North, Ft. Pierce, FL, 34946, USA, eguzman9@hboi.fau.edu.
authors.forename: Esther A
authors.initials: EA
authors.lastname: Guzmán
authors.forename: Kelly
authors.initials: K
authors.lastname: Maers
authors.forename: Jill
authors.initials: J
authors.lastname: Roberts
authors.forename: Hilaire V
authors.initials: HV
authors.lastname: Kemami-Wangun
authors.forename: Dedra
authors.initials: D
authors.lastname: Harmody
authors.forename: Amy E
authors.initials: AE
authors.lastname: Wright
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D001688:Biological Products / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019938:Cyclin D1 / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors*; D010190:Pancreatic Neoplasms / Q000188:drug therapy / Q000378:metabolism; D010456:Peptides, Cyclic / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001688:Biological Products; C508606:CXCL8 protein, human; D016209:Interleukin-8; D016328:NF-kappa B; D010456:Peptides, Cyclic; D016760:Proto-Oncogene Proteins c-fos; C587945:microsclerodermin A; D019938:Cyclin D1; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D051057:Proto-Oncogene Proteins c-akt; D048031:JNK Mitogen-Activated Protein Kinases; D038362:Glycogen Synthase Kinase 3; D020169:Caspases