Objective:To investigate whether CD3McAb activated killer(CD3AK)cells could induce apoptosis in HL 60 cells in serum free culture system.Methods:HL 60 cells were coincubated with CD3AK cells expanded in serum free medium,then apoptosis was assessed by means of morphological studies,DNA agarose gel electrophoresis and flow cytomether(FCM) analysis.Results:After 7 h of coincubation with CD3AK cells in serum free medium,HL 60 cells showed morphological features of apoptosis and typical DNA ladder on gel electrophoresis.FCM analysis showed that 24.59% cells were found to undergo apoptosis.Conclusion:CD3AK cells can induce apoptosis in HL 60 cells under serum free culture conditions.

AIM: To explore the relationship between methylation status of promoter region 5′CpG island and the biological phenotype in human colorectal cancer RKO cell lines. METHODS: RKO cells were treated with selective DNA methyltransferase (DNMTs) inhibitor, 5-Aza-2′-deoxycytidine (5-Aza-CdR), for 72 h. Methylation-specific PCR (MSP), T-A clone and DNA sequence analysis were used to detect 5′CpG island methylation status of p16/CDKN2 tumor suppresor gene. Cell growth, cell cycle arrest and apoptosis were analyzed by MTT, flow cytometry (FCM), fluorescent dye staining and transmission electron microscope. RESULTS: DNMTs inhibitor (5-Aza-CdR) effectively reversed the hypermethylation status of 5′CpG island. The effects of 5-Aza-CdR on cell growth inhibition (P