Proliferation- and apoptosis-associated factors in advanced prostatic carcinomas before and after androgen deprivation therapy: prognostic significance of p21/WAF1/CIP1 expression

Abstract

The molecular mechanisms leading to androgen-independent growth in prostate cancer (PC) are poorly understood. Androgen deprivation therapy (ADT) results physiologically in a decrease in proliferation and an increase in programmed cell death (PCD)/apoptosis. The aim of our study was to get more insight into these processes in prostatic carcinomas before and after ADT. For this purpose, immunohistologic staining for the androgen receptor (AR) molecule, the Ki-67 antigen, the bcl-2 oncoprotein, the p53 protein and its physiologic effector, p21/WAF1, was performed on archival material. PCD was visualized by enzymatic detection of DNA fragmentation. Specimens from 69 PC patients after ADT were studied in correlation to histopathology and prognosis. In 42 cases, corresponding tumour tissue from the untreated primary tumours could be analysed comparatively. Before ADT, histologic grade was associated with Ki-67 index ( P < 0.0001, Spearman correlation) and PCD rate ( P < 0.05, Spearman correlation). Ki-67 index correlated with PCD rate ( P < 0.05, Spearman correlation) and p21/WAF1 expression ( P < 0.01, Fisher's exact test). p21/WAF1 expression was the only statistically significant prognostic factor for shorter survival ( P < 0.002, log-rank test). All p21/WAF1-positive cases showed high Ki-67 index and high histologic grade. After ADT, loss of AR expression was associated with high Ki-67 index, whereas histologic signs of regression correlated negatively with Ki-67 index ( P < 0.001, Pearson χ 2 test). p21/WAF1 expression increased significantly ( P < 0.02, McNemar test) and correlated with p53 accumulation ( P < 0.0001, Pearson χ 2 test). Most significant prognostic parameter after conventional ADT was high-rate p21/WAF1 expression (> 50% of tumour cells; P < 0.00001, log-rank test). This study demonstrates that p21/WAF1 overexpression before and after ADT characterizes a subgroup of advanced PC with paradoxically high proliferation rate and significantly worse clinical outcome. This finding might be clinically useful for planning therapy in these patients. © 1999 Cancer Research Campaign

FISH Analysis of Gene Aberrations (MYC, CCND1, ERBB2, RB, and AR) in Advanced Prostatic Carcinomas Before and After Androgen Deprivation Therapy

“…Our recent immunohistological data showed impaired regulation of tumor cell proliferation and apoptosis in most cases of advanced PC before and after ADT (Baretton et al, 1999). For a better understanding of the genetic changes leading to androgenindependent growth in PC, two oncogenes (cMYC, ERBB2), the cell cycle control gene CCND1, the androgen receptor (AR) gene, and the RB tumorsuppressor gene were studied by FISH analysis.…”

“…As we could show recently by immunohistochemistry at the protein level, the physiologic regulation of proliferation and apoptosis is defective in the majority of advanced PC before ADT (Baretton et al, 1999). The genetic changes underlying androgen-independence and tumor progression are yet unclear.…”

“…DNA fragments of apoptotic cells were visualized by an enzymatic reaction (Gavrieli et al, 1992;Ansari et al, 1993) as previously described in detail (Baretton et al, 1999). As internal positive controls, preserved nonneoplastic prostatic glands within the slides from primary tumors or lymphocytes in lymph follicles were used.…”

“…Ki-67 immunohistochemistry was performed as previously described in detail (Baretton et al, 1999), using the MIB1/Ki-67 antibody (Dianova, Hamburg, Germany; dilution 1:1,000, prediluted in 1% bovine serum albumin; Sigma). According to the immunoreaction in 1,000 tumor cells per tumor, the mean and the maximal percentage of nuclei with a positive immunoreaction was determined (mean and maximal Ki-67 index).…”

The Significance of Key Regulators of Apoptosis in the Development and Prognosis of Prostate Carcinoma. I. Proteins of the BCL-2 Family and Protein P53

“…In patients with p53 mutation, apoptosis induction following androgen ablation may also be blocked 68 . Higher expression of mutated p53 was noted in patients in whom antiandrogen therapy was ineffective [92][93][94] . Studies show that neo-adjuvant hormonal therapy may cause selection of minor p53 mutated clones, rather than the induction of wild-type p53 and that positive p53 immunostaining correlates with AR gene amplification 94,95 .…”