EFFECT OF DIPYRIDAMOLE, 5'-(N-ETHYL)-CARBOXAMIDOADENOSINE AND 1,3-DIPROPYL-8-(2-AMINO-4-CHLOROPHENYL)-XANTHINE ON LOVO CELL-GROWTH AND MORPHOLOGY

The effects of stable compounds acting on adenosine receptors, 5'-(N-e thyl)-carboxamidoadenosine (NECA: A(2) and A(1) adenosine receptor ago nist) and 1,3-dipropyl-8-(2-amino-4-chlorophenyl)-xanthine (PACPX: sel ective A(1) adenosine receptor antagonist) were evaluated in vitro on doxorubicin-resistant LoVo (LoVo-R) and doxorubicin-sensitive LoVo (Lo Vo-S) human metastatic cell lines by using the neutral red test for ce ll growth. The effect of dipyridamole, an adenosine uptake inhibitor, was also evaluated. The drugs had an inhibitory effect on LoVo cell gr owth. The association of the drugs with doxorubicin enhanced the inhib ition of cell growth, particularly for NECA and PACPX on LoVo-R cells. Morphological observation with scanning electron microscopy indicated cytotoxicity of the tested compounds, alone or in association with do xorubicin both in LoVo-R or LoVo-S cells, supporting the hypothesis of inhibitory effect on tumor cell growth.