title: Synthesis and biochemical evaluation of benzoylbenzophenone thiosemicarbazone analogues as potent and selective inhibitors of cathepsin L.
abstract: Upregulation of cathepsin L in a variety of tumors and its ability to promote cancer cell invasion and migration through degradation of the extracellular matrix suggest that cathepsin L is a promising biological target for the development of anti-metastatic agents. Based on encouraging results from studies on benzophenone thiosemicarbazone cathepsin inhibitors, a series of fourteen benzoylbenzophenone thiosemicarbazone analogues were designed, synthesized, and evaluated for their inhibitory activity against cathepsins L and B. Thiosemicarbazone inhibitors 3-benzoylbenzophenone thiosemicarbazone 1, 1,3-bis(4-fluorobenzoyl)benzene thiosemicarbazone 8, and 1,3-bis(2-fluorobenzoyl)-5-bromobenzene thiosemicarbazone 32 displayed the greatest potency against cathepsin L with low IC50 values of 9.9 nM, 14.4 nM, and 8.1 nM, respectively. The benzoylbenzophenone thiosemicarbazone analogues evaluated were selective in their inhibition of cathepsin L compared to cathepsin B. Thiosemicarbazone analogue 32 inhibited invasion through Matrigel of MDA-MB-231 breast cancer cells by 70% at 10 μM. Thiosemicarbazone analogue 8 significantly inhibited the invasive potential of PC-3ML prostate cancer cells by 92% at 5 μM. The most active cathepsin L inhibitors from this benzoylbenzophenone thiosemicarbazone series (1, 8, and 32) displayed low cytotoxicity toward normal primary cells [in this case human umbilical vein endothelial cells (HUVECs)]. In an initial in vivo study, 3-benzoylbenzophenone thiosemicarbazone (1) was well-tolerated in a CDF1 mouse model bearing an implanted C3H mammary carcinoma, and showed efficacy in tumor growth delay. Low cytotoxicity, inhibition of cell invasion, and in vivo tolerability are desirable characteristics for anti-metastatic agents functioning through an inhibition of cathepsin L. Active members of this structurally diverse group of benzoylbenzophenone thiosemicarbazone cathepsin L inhibitors show promise as potential anti-metastatic, pre-clinical drug candidates.
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Erica N
authors.initials: EN
authors.lastname: Parker
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Jiangli
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: G D
authors.initials: GD
authors.lastname: Kishore Kumar
authors.affiliation: Institute of Biomedical Studies, Baylor University, One Bear Place #97224, Waco, TX 76798-7224, United States.
authors.forename: Samuel O
authors.initials: SO
authors.lastname: Odutola
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Gustavo E
authors.initials: GE
authors.lastname: Chavarria
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Amanda K
authors.initials: AK
authors.lastname: Charlton-Sevcik
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Tracy E
authors.initials: TE
authors.lastname: Strecker
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States.
authors.forename: Ashleigh L
authors.initials: AL
authors.lastname: Barnes
authors.affiliation: Department of Radiation Oncology, University of Florida Health Cancer Center, Gainesville, FL 32610, United States.
authors.forename: Dhivya R
authors.initials: DR
authors.lastname: Sudhan
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Wittenborn
authors.affiliation: Department of Radiation Oncology, University of Florida Health Cancer Center, Gainesville, FL 32610, United States; Department of Pharmacology and Therapeutics, College of Medicine, University of Florida, Gainesville, FL 32610, United States.
authors.forename: Dietmar W
authors.initials: DW
authors.lastname: Siemann
authors.affiliation: Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Horsman
authors.affiliation: OXiGENE, Inc., 701 Gateway Blvd, Suite 210, South San Francisco, CA 94080, United States.
authors.forename: David J
authors.initials: DJ
authors.lastname: Chaplin
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States; Institute of Biomedical Studies, Baylor University, One Bear Place #97224, Waco, TX 76798-7224, United States. Electronic address: Mary_Lynn_Trawick@baylor.edu.
authors.forename: Mary Lynn
authors.initials: ML
authors.lastname: Trawick
authors.affiliation: Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX 76798-7348, United States; Institute of Biomedical Studies, Baylor University, One Bear Place #97224, Waco, TX 76798-7224, United States. Electronic address: Kevin_Pinney@baylor.edu.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: Pinney
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology / Q000627:therapeutic use; D001577:Benzophenones / Q000737:chemistry; D001665:Binding Sites; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism; D056668:Cathepsin L / Q000037:antagonists & inhibitors* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology / Q000627:therapeutic use; D015195:Drug Design; D005260:Female; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D007536:Isomerism; D007700:Kinetics; D015674:Mammary Neoplasms, Animal / Q000188:drug therapy; D051379:Mice; D062105:Molecular Docking Simulation; D017434:Protein Structure, Tertiary; D013882:Thiosemicarbazones / Q000737:chemistry* / Q000494:pharmacology / Q000627:therapeutic use; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D001577:Benzophenones; D015853:Cysteine Proteinase Inhibitors; D013882:Thiosemicarbazones; C047723:benzophenone; D002401:Cathepsin B; D056668:Cathepsin L
keywords: Anti-metastatic agents; Cathepsin L inhibitors; Inhibition of cancer cell invasion and migration; Small-molecule synthesis; Thiosemicarbazone warhead