The expression of PML in chronic myeloid leukemia and effect on cell proliferation

Abstract

Objective To investigate whether PML is expressed differently in chronic myeloid leukemia (CML) patients and healthy controls,then explore the effect of PML on proliferation in leukemia cell lines K562. Methods Real-time PCR was used to detect the PML expression in peripheral blood mononuclear cells from 30 chronic myeloid leukemia patients and 24 healthy controls.Plasmids containing full length PML were constructed and transfected into K562 cell line to screen clones stably expressing PML,the clones stably expressing empty vector as a control.MTT assay and flow cytometry were used to detect the effect of PML on K562 cell proliferation and cell cycle.Furthermore,RT-PCR and western blot were used to detect c-myc and p27kip1 (p27) mRNA and protein expression.Lastly,the mRNA levels of c-myc and p27 were detected in CML patients and healthy controls. Results The mRNA level of PML in CML patients (ΔCt=9.02±0.74) was significantly lower than the healthy controls (ΔCt=7.91±0.34) and the difference was statistically significant (t=5.07,P<0.001).PML over-expression could inhibit the proliferation of K562 cells obviously and cause G0/G1 cell cycle arrest.In addition,c-myc mRNA and protein expression decreased while p27 mRNA and protein expression increased in K562 cells with stably expressed PML compared with vector control.The mRNA level of c-myc in CML patients (ΔCt=7.13±0.43) was significantly higher than the healthy controls (ΔCt=9.35±0.82) and the difference was statistically significant (t=6.78,P<0.001),while the m RNA level of p27 in CML patients (ΔCt=4.56±0.58) was significantly lower than the healthy controls (ΔCt=3.29±0.92) and the difference was statistically significant (t=2.93,P<0.01). Conclusions PML protein is expressed highly in healthy controls,whereas its expression is declined significantly in chronic myeloid leukemia patients.PML may inhibit leukemia cell proliferation through regulating c-myc and p27 expression. (Chin J Lab Med,2013,36:395-399) Key words: Nuclear proteins; Transcription factors; Tumor suppressor proteins; Leukemia; myelogenous; chronic; BCR-ABL prositive; Cell proliferation