title: Antitumour potential of BPT: a dual inhibitor of cdk4 and tubulin polymerization.
abstract: The marine natural product fascaplysin (1) is a potent Cdk4 (cyclin-dependent kinase 4)-specific inhibitor, but is toxic to all cell types possibly because of its DNA-intercalating properties. Through the design and synthesis of numerous fascaplysin analogues, we intended to identify inhibitors of cancer cell growth with good therapeutic window with respect to normal cells. Among various non-planar tryptoline analogues prepared, N-(biphenyl-2-yl) tryptoline (BPT, 6) was identified as a potent inhibitor of cancer cell growth and free from DNA-binding properties owing to its non-planar structure. This compound was tested in over 60 protein kinase assays. It displayed inhibition of Cdk4-cyclin D1 enzyme in vitro far more potently than many other kinases including Cdk family members. Although it blocks growth of cancer cells deficient in the mitotic-spindle checkpoint at the G0/G1 phase of the cell cycle, the block occurs primarily at the G2/M phase. BPT inhibits tubulin polymerization in vitro and acts as an enhancer of tubulin depolymerization of paclitaxel-stabilized tubulin in live cells. Western blot analyses indicated that, in p53-positive cells, BPT upregulates the expression of p53, p21 and p27 proteins, whereas it downregulates the expression of cyclin B1 and Cdk1. BPT selectively kills SV40-transformed mouse embryonic hepatic cells and human fibroblasts rather than untransformed cells. BPT inhibited the growth of several human cancer cells with an IC50<1 μM. The pharmacokinetic study in BALB/c mice indicated good plasma exposure after intravenous administration. It was found to be efficacious at 1/10th the maximum-tolerated dose (1000 mg/kg) against human tumours derived from HCT-116 (colon) and NCI-H460 (lung) cells in SCID (severe-combined immunodeficient) mice models. BPT is a relatively better anticancer agent than fascaplysin with an unusual ability to block two overlapping yet crucial phases of the cell cycle, mitosis and G0/G1. Its ability to effectively halt tumour growth in human tumour-bearing mice would suggest that BPT has the potential to be a candidate for further clinical development.
authors.affiliation: School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK.
authors.forename: S
authors.initials: S
authors.lastname: Mahale
authors.affiliation: 1] Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India [2] Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: S B
authors.initials: SB
authors.lastname: Bharate
authors.affiliation: 1] Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India [2] Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: S
authors.initials: S
authors.lastname: Manda
authors.affiliation: 1] Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India [2] Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: P
authors.initials: P
authors.lastname: Joshi
authors.affiliation: Department of Chemistry, University of Leicester, Leicester LE1 7RH, UK.
authors.forename: P R
authors.initials: PR
authors.lastname: Jenkins
authors.affiliation: 1] Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India [2] Academy of Scientific and Innovative Research (AcSIR), CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
authors.forename: R A
authors.initials: RA
authors.lastname: Vishwakarma
authors.affiliation: School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK.
authors.forename: B
authors.initials: B
authors.lastname: Chaudhuri
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001713:Biphenyl Compounds / Q000737:chemistry / Q000494:pharmacology*; D002243:Carbolines / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D051358:Cyclin-Dependent Kinase 4 / Q000037:antagonists & inhibitors* / Q000737:chemistry; D005260:Female; D045325:HCT116 Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D056004:Molecular Dynamics Simulation; D058105:Polymerization / Q000187:drug effects; D011897:Random Allocation; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D001713:Biphenyl Compounds; D002243:Carbolines; D014404:Tubulin; C009804:tryptoline; C495902:Cdk4 protein, mouse; D051358:Cyclin-Dependent Kinase 4