title: Heparin and suramin alter plitidepsin uptake via inhibition of GPCR coupled signaling.
abstract: Plitidepsin (Aplidin) is a novel antitumor agent, derived from the mediterranean tunicate Aplidium albicans, and is currently in phase ii clinical trials with evidence of activity in heavily pretreated multiple myeloma, renal cell carcinoma, melanoma and neuroblastoma patients. As compared to its parental compound didemnin B, plitidepsin has shown a better therapeutic index with less bone marrow toxicity, cardiotoxicity and neurotoxicity in patients and a more potent cytotoxic effect in several tumor cell lines. As sensitivity to the drug varies between cell lines and fresh leukemia samples, we performed studies on transport of plitidepsin in leukemia and lymphoma cell lines to determine the mechanism of uptake. The drug is taken up by an active transport process, i.e. the process is temperature and energy dependent, and has a high-affinity binding site with Kt =212 nM and Vmax = 15 pmoles/min. Importantly, once inside the cell, efflux of plitidepsin is minimum, suggesting that the drug is bound to intracellular macromolecules. Further work showed that plitidepsin binds to G-Protein Coupled Receptors (GPCRs), since GPCR and GRK (GPCR kinases) inhibitors suramin and heparin respectively, markedly reduce the drug uptake and its cytotoxic activity. Signaling via Jak/Stat pathway is inhibited by pharmacological concentrations of plitidepsin, further confirming the relationship between plitidepsin and GPCRs.
authors.affiliation: Department of Medicine and Pharmacology, Robert Wood Johnson Medical School, Cancer Institute of New Jersey, University of Medicine and Dentistry of New Jersy, New Brunswick, NJ 08903, USA.
authors.forename: G S A
authors.initials: GS
authors.lastname: Longo-Sorbello
authors.forename: H
authors.initials: H
authors.lastname: Gao
authors.forename: P J
authors.initials: PJ
authors.lastname: Mishra
authors.forename: B
authors.initials: B
authors.lastname: Kamen
authors.forename: A
authors.initials: A
authors.lastname: Soto
authors.forename: J
authors.initials: J
authors.lastname: Jimeno
authors.forename: M
authors.initials: M
authors.lastname: Aracil
authors.forename: M F
authors.initials: MF
authors.lastname: Paz de Paz
authors.forename: J R
authors.initials: JR
authors.lastname: Bertino
authors.forename: D
authors.initials: D
authors.lastname: Banerjee
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000378:metabolism; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001693:Biological Transport, Active; D049109:Cell Proliferation; D003561:Cytarabine / Q000494:pharmacology; D047630:Depsipeptides / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D010456:Peptides, Cyclic; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000378:metabolism; D050791:STAT Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism; D013347:Subcellular Fractions; D013498:Suramin / Q000494:pharmacology*; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D000964:Antimetabolites, Antineoplastic; D047630:Depsipeptides; D010456:Peptides, Cyclic; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D043562:Receptors, G-Protein-Coupled; D050791:STAT Transcription Factors; D003561:Cytarabine; D013498:Suramin; D000255:Adenosine Triphosphate; D006493:Heparin; D015761:4-Aminopyridine; D048031:JNK Mitogen-Activated Protein Kinases; C098980:plitidepsin