Expression of apoptosis-stimulating protein of p53 family members in invasive breast cancer and its prognostic significance

Objective To explore the expression of apoptosis-stimulating protein of p53 (ASPP) family members in invasive breast cancer and their relationship with p53 expression, molecular subtype and prognosis of patients. Methods The tissue samples from 155 invasive breast cancer patients in the Department of Pathology, No. 989 Hospital of PLA from January 2005 to April 2010 were analyzed retrospectively. The expression of ASPP family members (ASPP1, ASPP2, iASPP), p53, ER, PR, HER-2 and Ki67 in breast cancer tissue samples was detected by immunohistochemistry. The relationship between the expression of ASPP family members and different molecular subtypes or p53 expression were analyzed by χ2 test, and the Kaplan-Meier method was used to analyze the relationship between expression of ASPP family members and patient survival. Results In the invasive breast cancer tissue samples of 155 cases, the positive rate of ASPP1 was 13.5% (21/155), ASPP2 97.4% (151/155), and iASPP 61.3% (95/155). There were 33 cases of wild-type p53 expression and 122 cases of p53 mutation expression, so the mutation rate of p53 was 78.7% (122/155). There was no significant difference in the expression of ASPP family members between the wild-type p53 expression group and p53 mutation group (ASPP1: χ2<0.001, P=0.987; ASPP2: χ2=1.110, P=0.579; iASPP: χ2=0.244, P=0.621). There were 44 patients with luminal A subtype breast cancer, 66 luminal B, 18 basal-like and 27 HER-2 over-expression in all 155 patients, suggesting no significant difference in the expression of ASPP family members across different subtypes(ASPP1: χ2=2.325, P=0.508; ASPP2: χ2=1.657, P=0.642; iASPP: χ2=0.815, P=0.846). The patients were followed up for 2-108 months, median 66 months. The 3-year survival rate was 84.5% (131/155) and 5-year survival rate was 79.4% (123/155). There was no significant difference between ASPP1/ASPP2/iASPP positive group and negative group in the 5-year survival (ASPP1: χ2=3.790, P=0.050; ASPP2: χ2=0.040, P=0.927; iASPP: χ2=1.253, P=0.263). Conclusions The expression of ASPP family members in invasive breast cancer is not related to p53 mutation, molecular subtype and survival. Key words: Breast neoplasms; Apoptosis; Molecular typing; Prognosis; Tumor suppressor protein p53