ABSTRACT
OBJECTIVE Toinvestigatethedifferenceofcytotoxiceffectsofhydroxycamptothecin(HCPT)onhuman lungcancercelsA549andhumanembryolungfibroblastcelsMRC-5.METHODS A549celsandMRC-5celswere treated with HCPT 20-200 μmol·L-1 for 24,48 and 72 h,or pulse treated with HCPT 50-400 μmol·L-1 for 24 h along with 5 d release.cellsurvival was detected by MTT assay.Morphological changes for both types of cells were observed under an inverted phase-contrast microscope.cellcycle and apoptosis in both cells treated with HCPT 50 μmol·L-1 for 48 h weredeterminedbyflowcytometry.RESULTS HCPT20-200μmol·L-1inhibitedthesurvivalofbothcelsinaconcen-tration-dependent manner and more cytotoxicity was observed in A549 cells for 48 h.The concentration-effect correlation coefficient(r)of HCPT in A549 and MRC-5 cells for 48 h was 0.898 (P=0.015)and 0.996 (P=2.56E-5)respectively. The inhibition rates were significantly different between A549 and MRC-5 cells with treatment of HCPT 20,50,80,1 00, 1 60 and 200 μmol·L-1 for 48 h (P<0.05).The IC50 of HCPT on A549 and MRC-5 cells was (24.00 ±0.69)μmol·L-1 and (1 23.63 ±3.89)μmol·L-1 respectively,indicating that A549 cells were 5-fold more sensitive to HCPT than MRC-5 cells at 48 h.After exposure to HCPT 50 μmol·L-1 for 48 h,some A549 cells were rounded up and shrank dramatical y, and some cells underwent membrane blebbing or lysing while MRC-5 cells had no obvious changes.cellcycle and apop-tosis analysis showed that A549 cells were arrested at both S and G2/M phases and apoptosis occurred but MRC-5 cells were just arrested at S phase.In the recovery growth curve,the growth of A549 cells was inhibited to a larger extent than MRC-5 cells and the growth retardation stil existed for 24 h in both cells.The survival of MRC-5 cells was faster than that ofA549cels,althoughtherewasnocompleterecoveryineithercel.CONCLUSION A549celsaremoresensitiveto HCPT than MRC-5 cells due to the fact that HCPT induces cellcycle arrest at both S and G2/M phases and apoptosis in A549 cells,but only triggers S phase arrest in the MRC-5 cells.