1. Academic Validation
  2. Pronounced anti-proliferative activity and tumor cell selectivity of 5-alkyl-2-amino-3-methylcarboxylate thiophenes

Pronounced anti-proliferative activity and tumor cell selectivity of 5-alkyl-2-amino-3-methylcarboxylate thiophenes

  • Eur J Med Chem. 2017 May 26:132:219-235. doi: 10.1016/j.ejmech.2017.03.044.
Joice Thomas 1 Alenka Jecic 2 Els Vanstreels 2 Lizette van Berckelaer 2 Romeo Romagnoli 3 Wim Dehaen 4 Sandra Liekens 5 Jan Balzarini 6
Affiliations

Affiliations

  • 1 KU Leuven, Department of Chemistry, Celestijnenlaan 200f, B-3001 Leuven, Belgium.
  • 2 KU Leuven, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, B-3000 Leuven, Belgium.
  • 3 Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, 44121 Ferrara, Italy.
  • 4 KU Leuven, Department of Chemistry, Celestijnenlaan 200f, B-3001 Leuven, Belgium. Electronic address: wim.dehaen@kuleuven.be.
  • 5 KU Leuven, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, B-3000 Leuven, Belgium. Electronic address: Sandra.liekens@kuleuven.be.
  • 6 KU Leuven, Rega Institute for Medical Research, Herestraat 49, Postbus 1043, B-3000 Leuven, Belgium. Electronic address: jan.balzarini@kuleuven.be.
Abstract

5-(2-(4-Methoxyphenyl)ethyl)-2-amino-3-methylcarboxylate thiophene (TR560) is the prototype drug of a recently discovered novel class of tumor-selective compounds that preferentially inhibit the proliferation of specific tumor cell types (e.g. leukemia/lymphoma). Here, we further increased tumor selectivity by simplification of the molecule through replacing the 4-methoxyphenyl moiety by an alkyl chain. Several 2-amino-3-methylcarboxylate thiophene derivatives containing at C-5 an alkyl group consisting of at least 6 (hexyl) to 9 (nonyl) carbon units showed pronounced anti-proliferative activity in the mid-nanomolar range with 500- to 1000-fold tumor cell selectivity. The compounds preferentially inhibited the proliferation of T-lymphoma CEM and Molt/4, prostate PC-3, kidney Caki-1 and hepatoma Huh-7 tumor cells, but were virtually inactive against Other tumor cell lines including B-lymphoma Raji and cervix carcinoma HeLa cells. The novel prototype drug 3j (containing a 5-heptyl chain) elicited a cytotoxic, rather than cytostatic activity, already after 4 h of exposure. The unusual tumor selectivity could not be explained by a differential uptake (or efflux) of the drug by sensitive versus resistant tumor cells. Exposure of a fluorescent derivative of 3j revealed pronounced uptake of the drug in the cytoplasm, no visible appearance in the nucleus, and a predominant localization in the endoplasmic reticulum. These observations may be helpful to narrow down the intracellular localization and identification of the molecular target of the 5-substituted thiophene derivatives.

Keywords

5-Alkyl-2-aminothiophenes; Anti-proliferative activity; Gewald reaction; Intracellular uptake; Tumor selectivity.

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