Objective To evaluate whether hypermethylation of calcitonin (CT) gene could serve as a transforming signal of myelodysplastic syndrome (MDS) to leukemia.Methods Bone marrow aspirates from 35 MDS patients, including 25 refractory anemia (RA), 10 refractory anemia with excess of blasts (RAEB) or refractory anemia with excess of blasts in transformation (RAEBt) and 7 cases of acute myeloid leukemia (AML) transformed from MDS, were studied on methylation rate in 5'end of CT gene by polymerase chain reaction (PCR) technique using methylation-sensitive endonuclease HpaⅡ with external references of undigested DNA and MspⅠ digested DNA and internal reference of 112 bp fragment containing codon 61 of N-ras oncogene. The results were expressed as calcitonin gene methylation rate (CTMR) calculated from the densitometer-analyzed integral calculus of PCR products of 566 bp CT(a1), 112 bp N-ras(b1) by using HpaⅡ-digested DNA and PCR products of 566 bp CT(a0), 112 bp N-ras(b0) by using undigested DNA according to the formula, CTMR = (a1/b1)/(a0/b0)×100%.Results The CTMRs in total 35 MDS, 25 RA, 10 RAEBt and 7 cases of AML transformed from MDS were 36.87%±25.10%, 28.12%±24.01%, 58.74%±16.49%, and 54.03%±7.06% respectively, significantly higher than that in control group (P<0.001, P<0.05, P<0.001 and P<0.001, respectively). Conclusion The results suggest that hypermethylation of CT gene occurs in early stage of leukemic transformation and CTMR might be a useful marker in predicting the transformation of MDS to AML.

According to our previous experiments, Ph(+) chronic myeloid leukemia (CML) cell line K562 cells have defects in beta 1 integrin activation. In order to search the same regularity in Ph(+) CML bone marrow cells, bone marrow mononuclear cells (BMMNC) from 12 cases of Ph(+) CML and 10 cases of normal individuals were studied. Their expression rate of 9EG7 epitope on beta1 integrin post treatment by 8A2 or GM- or G-CSF and cell adhesion ability with soluble fibronectin (FN) were evaluated by flow cytometry; in addition, the effects of CGP57148B, a highly specific ABL tyrosine kinase inhibitor, were observed. Our results showed that 9EG7 expression rate and FN binding rate were very low in all the inactivated cells. The parameter increased markedly post 8A2 activation in both NBMMNCs and CMLBMMNCs, but the degree of increase in CMLBMMNCs was significantly lower than that in NBMMNCs; GM-CSF or G-CSF could significantly increase the parameters in NBMMNCs while had no effects on that in CMLBMMNCs. CGP57148B could increase the beta1 integrin activation potential of CMLBMMNCs but had no effects on that of NBMMNCs. The results indicate that decreased activation potential of beta1 integrin in CMLBMMNCs is the major cause of adhesion defects of Ph(+) CML cells; beta1 integrin functional insufficiency in CMLBMMNCs could not be directly reversed by ABL tyrosine kinase inhibitor CGP57148B.