Abstract: Objective To evaluate the predictive value of pituitary tumor transforming gene (PTTG) and cycle-dependent kinase inhibitor 1A (p21) in the prognosis of pituitary adenomas underwent radiotherapy. Methods A total of 89 postoperative patients with non-functional pituitary adenomas(NFPAs) treated by gamma knife radiosurgery (GKRS) from 2003 to 2013 were collected.The cases were divided into research and validation cohorts based on the radiosurgery operation time. According to the follow-up MRI, a decrease of tumor more than 20% was defined as radiosensitive; Expression of sixteen protein markers in pituitary adenomas was determined using a tissue microarray. Results Univariate analysis revealed that nucleus positive PTTG(HR:1.355; P＜0.05 or HR:1.637; P＜0.01) and cytoplasm high expression of p21(HR:1.174; P＜0.01 or HR:1.378; P＜0.01) were significantly correlated with radiation resistance in both research and validation group. In the research group, Kaplan Meyer (KM) curve analysis showed patients with nucleus negative PTTG (P＜0.01) and cytoplasm low expression of p21(P＜0.01) had a higher radiosensitivity, the same results were obtained in the validation group(PTTG,P＜0.05; p21,P＜0.01). Conclusions Patients with nucleus positive PTTG and cytoplasm high expression of p21 tend to be resistant to radiotherapy in pituitary adenomas; PTTG and p21 are prognostic protein markers associated with radiation resistance.

Key words: pituitary tumor transforming gene(PTTG), cycle-dependent kinase inhibitor 1A(p21), tissue microarray, radiation resistance