p27 expression and proliferation in gastrointestinal stromal tumors.

BACKGROUND/AIMS: The p27 is a cyclin-dependent kinase inhibitor which plays a pivotal role in cell proliferation during development and tumorigenesis. Recently, it was shown that low expression of p27 tends to occur in more aggressive neoplasms. In gastrointestinal stromal tumors p27 expression and its correlation with proliferation remain to be elucidated. The aim of the present study was to investigate the expression of p27 and proliferation in gastrointestinal stromal tumors.

METHODS

p27 and Ki-67 immunostained tissue sections from 45 gastrointestinal stromal tumors (benign, borderline and malignant) were subjected to quantitative analysis, and p27 labelling index and Ki-67 labelling index were obtained for each case.

RESULTS

The mean values of Ki-67 labelling index in the three groups were significantly different (benign, 4.53%; borderline, 9.82%; and malignant, 15.35%) (p<0.05). p27 labelling index was decreased in malignant tumors (10.46%) compared with benign (36.56%) and borderline tumors (21.36%) (p<0.05). Moreover, in each group p27 labelling index exhibited a significant inverse relation to p67 labelling index (p<0.001).

CONCLUSION

Our results suggest that decreased levels of p27 labelling index could predict the malignant behavior of gastrointestinal stromal tumors and might be associated with tumor cell proliferative activity.