OBJECTIVETo investigate the effect of a selective inducible nitric oxide synthase(iNOS) inhibitor, aminoguanidine (AG), on the proliferation and apoptosis of human colorectal cancer (CRC) Lovo cell line, and explore its possible mechanism.

METHODSMTT assay was used to detect the inhibition of Lovo cell growth by aminoguanidine. Apoptosis and cell cycle of Lovo cells were examined by flow cytometry (FCM). Morphologic change of Lovo cell treated by AG was observed with AO/EB staining.

RESULTSThere were significant differences in 0.5 mmol/L and 1.0 mmol/L AG groups as compared to the control group (P<0.05). The absorbance (A) values of Lovo cells in each time point were significantly different (P<0.05). Growth of Lovo cells was inhibited by aminoguanidine in a dose- and time-dependent manner. FCM analysis showed that the cell ratio of G(0)/G(1) phase increased with the increasing of the concentration of aminoguanidine, but the cell ratio of S-and G(2)/M phase decreased correspondingly (P<0.05). S phase fraction and proliferation index (PI) decreased remarkably, and the apoptotic rate of Lovo cells increased. After AG treatment, AO/EB staining revealed some apoptotic morphological features such as cell shrinkage, nuclear condensation, DNA fragmentation, and formation of apoptosis bodies.

CONCLUSIONSAminoguanidine inhibits the proliferation and facilitates the apoptosis of human CRC Lovo cells. One of the mechanisms may be explained as blocking the progress of cell cycle of CRC Lovo cells by aminoguanidine.