Aims: The purpose of this study was the synthesis of some new thienopyrimidine derivatives of
1,3-disubstituted benzimidazoles and the evaluation of their cytotoxicity against MDA-MB-231, MCF-7, and
3T3 cells lines.
Background: An overexpression or mutational activation of TK receptors EGFR and HER2/neu is characteristic
of tumors. It has been found that some thieno[2,3-d]pyrimidines exhibited better inhibitory activity against
Epidermal Growth Factor Receptor (EGFR/ErbB-2) tyrosine kinase in comparison to aminoquinazolines. Breast
cancer activity towards MDA-MB-231 and MCF-7 cell lines by inhibiting EGFR was revealed by a novel
2-arylbenzimidazole. This motivated the synthesis of new thienopyrimidines possessing benzimidazole
fragments in order to evaluate their cytotoxicity to the above-mentioned cell lines.
Objective: The objectives of the study were to design and synthesize a novel series of thieno[2,3-d]pyrimidines
bearing biologically active moieties, such as 1,3-disubstituted-benzimidazole heterocycle, structurally similar to
diaryl ureas in order to evaluate their cytotoxicity against MDA-MB-231, and MCF-7 breast cancer cell lines.
Methods: N,N-disubstituted benzimidazole-2-one carbonitriles were synthesized by Aza-Michael addition and
used as precursors to generate some of the new thieno[2,3-d]pyrimidines in acidic medium The interaction of
chloroethyl-2-thienopyrimidines, 2-amino-benzimidazole and benzimidazol-2-one nitriles under solid-liquid
transfer catalysis conditions led to new thienopyrimidines. MTT assay for cell survival was performed in order
to evaluate the cytotoxicity of the tested compounds. A fluorescence study was conducted to elucidate some
aspects of the mechanism of action.
Results: The effects of nine synthesized compounds were investigated towards MDA-MB-231, MCF-7 and 3T3
cell lines. Thieno[2,3-d]pyirimidine-4-one 16 (IC50 - 0.058μM) and 21 (IC50 - 0.029μM) possess high cytotoxicity
against MDA-MB-231 cells after 24h. The most cytotoxic compounds against breast cancer MCF-7 cells was
compound 21 (IC50 - 0.074μM), revealing lower cytotoxicity against mouse fibroblast 3T3 cells with IC50 - 0.20μM.
SAR analysis was performed. Fluorescence study of the treatment of MDA-MB cells with compound 21 was
carried out in order to clarify some aspects of the mechanism of action.
Conclusion: The relationship between cytotoxicity of compounds 14 and 20 against MCF-7 and 3T3 cells can
suggest a similar mechanism of action. The antitumor potential of the tested compounds proves the necessity for
further investigation to estimate the exact inhibition pathway in the cellular processes. The fluorescence study of
the treatment of MDA-MB cells with compound 21 showed a rapid process of apoptosis.