Research paper
β-Lactams with antiproliferative and antiapoptotic activity in breast and chemoresistant colon cancer cells

https://doi.org/10.1016/j.ejmech.2020.112050Get rights and content
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Highlights

  • Ring B modified β-Lactam Combretastatin A-4 analogues synthesised.

  • Antiproliferative effects in UGT-expressing chemoresistant HT-29 colon cancer cells.

  • Compounds inhibit tubulin polymerisation.

  • G2M arrest and apoptosis demonstrated in MCF-7 breast cancer cells.

  • Glucuronidation in HT-29 cells may be inhibited by modification of ring B.

Abstract

A series of novel 1,4-diaryl-2-azetidinone analogues of combretastatin A-4 (CA-4) have been designed, synthesised and evaluated in vitro for antiproliferative activity, antiapoptotic activity and inhibition of tubulin polymerisation. Glucuronidation of CA-4 by uridine 5-diphosphoglucuronosyl transferase enzymes (UGTs) has been identified as a mechanism of resistance in cancer cells. Potential sites of ring B glucuronate conjugation are removed by replacing the B ring meta-hydroxy substituent of selected series of β-lactams with alternative substituents e.g. F, Cl, Br, I, CH3. The 3-phenyl-β-lactam 11 and 3-hydroxy-β-lactam 46 demonstrate improved activity over CA-4 in CA-4 resistant HT-29 colon cancer cells (IC50 = 9 nM and 3 nM respectively compared with IC50 = 4.16 μM for CA-4), while retaining potency in MCF-7 breast cancer cells (IC50 = 17 nM and 22 nM respectively compared with IC50 = for 4 nM for CA-4). Compound 46 binds at the colchicine site of tubulin, and strongly inhibits tubulin assembly at micromolar concentrations comparable to CA-4. In addition, compound 46 induced mitotic arrest at low concentration in both cell lines MCF-7 and HT-29 together with downregulation of expression of antiapoptotic proteins Mcl-1, Bcl-2 and survivin in MCF-7 cells. These novel antiproliferative and antiapoptotic β-lactams are potentially useful scaffolds in the development of tubulin-targeting agents for the treatment of breast cancers and chemoresistant colon cancers.

Keywords

Combretastatin A-4
Antiproliferative activity
1,4-Diaryl-2-azetidinone
Tubulin polymerisation
Cell cycle arrest
Microtubule targeting agent

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