ABSTRACT
p27(Kip1) (p27), a cyclin-dependent kinase inhibitor, has an important role in the progression of cells from G(1) into S phase of the cell cycle. p27 may act as a tumor suppressor, and several reports suggest that loss of its expression in breast carcinoma is related to tumor progression and poor prognosis. We evaluated p27 immunohistochemical expression in 512 consecutive cases of breast carcinoma with 9 years of median-term follow-up. p27 expression was heterogeneous and frequently less intense than in normal cells. Low p27 expression (<50% of reacting cells) was associated with grade III tumors, N0 status, estrogen receptor-negative status, and low cyclin D1 expression. In the whole series of cases, p27 expression did not predict outcome. In node-negative cases (249 patients), high p27 expression indicated poor prognosis. p27 was not prognostically relevant in the group of 223 patients with pT1 disease or in the group of 154 patients <50 years of age. We also investigated the prognostic value of the combined expression of p27 and cyclin D1, but no differences in survival were seen in this bivariate analysis.
Subject(s)
Breast Neoplasms/metabolism , Cell Cycle Proteins , Microtubule-Associated Proteins/biosynthesis , Tumor Suppressor Proteins , Adult , Aged , Carcinoma, Ductal, Breast/metabolism , Cyclin-Dependent Kinase Inhibitor p27 , Disease-Free Survival , Female , Follow-Up Studies , Humans , Immunohistochemistry , Lymphatic Metastasis , Menopause , Middle Aged , Recurrence , Time FactorsABSTRACT
Bax and Bcl2 are functionally antagonistic proteins which control apoptosis, whose expression in human tumours could be of prognostic value. We evaluated Bax and Bcl2 expression in 239 breast carcinomas (99 N0, 140 N1/2) with long term follow-up (median 79 months, range 11-140) in relation to clinico-pathologic parameters, clinical outcome, adjuvant therapy and expression of oestrogen receptor protein and p53. The prognostic value of Bax was investigated in the whole series of patients and in subgroups of homogeneously staged and treated patients (i.e., node-negative, N1/2 CMF-treated, N1/2 tamoxifen-treated). Bax immunostaining was cytoplasmic and heterogeneous. Cases were scored as Bax-positive if there were more than 20% reacting cells. High Bax expression was associated with positive nodal status (p = 0.03) and high Bcl2 expression (p = 0.01) and was more frequent in high-grade tumours. In the node-negative subgroup, Bax expression was associated with small tumour size. No association was seen with other parameters or with clinical outcome in any subgroup of patients. Since the apoptotic rate of a tumour is influenced by the ratio Bcl2/Bax, we investigated the combined effects of Bax and Bcl2 expression in relation to clinical outcome. However, no differences in survival were seen in the Bcl2-negative and Bcl2-positive groups when they were subdivided on the basis of the level of Bax expression and vice versa. In experimental systems, p53 is a direct transcriptional activator of the human bax gene. However, we could not observe any relation between Bax and p53 expression. We investigated whether the combined p53/Bax expression could have any prognostic value since it is predicted that tumours with normal p53 expression and concurrent high levels of Bax should be less aggressive and more susceptible to therapy. However, while p53 itself was of prognostic value, Bax expression was not related to prognosis in p53-negative or in p53-positive groups.
