Objective      To evaluate the expression of protein microcephalin (MCPH1

also known as BRCT-repeat inhibitor of hTERT expression

BRIT1) in lung tissues and investigate the effects of its over-expression on the apoptosis of human lung cancer cell line H1299.       Methods      The protein expression of MCPH1 in 20 tissue samples of lung cancer and 8 samples of normal lung tissues were studied by immuno-histochemistry. Eukaryotic expression plasmid pcDNA3.1(-)/ MCPH1 and b

lank plasmid pcDNA3.1 were transferred to lung cancer cells H1299

and the cells without transfection served as control. In 48 h after transfection

the cells were detected for transcription and expression of MCPH1 mRNA by real-time PCR. In 72 h after transfection

the total protein was extracted and the MCPH1 protein were determined by Western blotting. The apoptosis of H1299 cells was determined by flow cytometry.       Results      The expression of MCPH1 occurred mainly in the nucleus of normal tissues and was much lower in lung cancer tissues than in normal tissues. Both the expression of MCPH1 mRNA and protein were up-regulated effectively in H1299 cells after transfection with plasmid pcDNA3.1(-)/MCPH1. The apoptotic rate of H1299 cells transfected with plasmid pcDNA3.1(-)/MCPH1 was significantly higher than those transfected with the blank plasmid and those untransfected [(18.10±1.87)%

vs

(5.76±1.85)% and (5.85±0.57)%

P

<

0.05

]

.       Conclusion      MCPH1 protein is expressed in the cytoplasm of lung cancer tissues with lower expression. Over-expression of MCPH1 significantly induces the apoptosis of human lung cancer cells

in vitro

.