p53 Alteration and Chromosomal Instability in Prostatic High-Grade Intraepithelial Neoplasia and Concurrent Carcinoma: Analysis by Immunohistochemistry, Interphase In Situ Hybridization, and Sequencing of Laser-Captured Microdissected Specimens

Abstract

p53 mutation has been shown to be associated with chromosomal instability (CI) in many human dysplastic and neoplastic lesions. However, the precise role of p53 in the pathogenesis of prostate carcinoma (Pca) is unknown. Topographic analysis of p53 alteration using immunohistochemistry (IHC) was performed on 35 archived prostatectomy specimens containing Pca foci; high-grade prostrate intraepithelial neoplasia (HPIN) foci intermingled with cancer (HPINI) and situated away (HPINA). Specimens from 2 patients were topographically genotyped using laser capture microdissection, PCR amplification, and direct sequencing of p53 exons 5-9. CI was evaluated in the same tissue foci by interphase in situ hybridization (IFISH) using centromere probes for chromosomes 7, 8, and Y. p53 immunoreactivity was found in 20%, 17%, 0, and 0 in Pca, HPINI, HPINA, and benign epithelium, respectively. p53 molecular analysis in the specimens examined confirmed the IHC findings. IFISH revealed numerical chromosomal alterations in keeping with CI in 71% and 25% of p53؉ and p53؊ Pca, respectively (P ‫؍‬ .1), 67% and 0 of p53؉ and p53؊ HPIN, respectively (P < .02), and in 27% and 0 of HPINI and HPINA, respectively. We concluded that p53 mutation is an early change in at least a subset of Pca. HPINI foci tend to have higher overall p53 immunoreactivity and CI than HPINA. The presence of p53 mutation in HPIN was associated with the presence of CI as determined by IFISH. Our study also provided additional evidence in support of the concept that HPIN might be the earliest precursor of cancer. Furthermore, our studies identify genomic similarities in HPINI and Pca, implying that carcinoma may arise from progression of certain HPIN foci that most likely harbor p53 mutation and/or more CI. KEY WORDS: Chromosomal instability, Immunohistochemistry, In situ hybridization, p53 sequencing, Prostate carcinoma, Prostate intraepithelial neoplasia.

Evidence of multifocality of telomere erosion in high-grade prostatic intraepithelial neoplasia (HPIN) and concurrent carcinoma

“…Chromosomal instability and numerical aberrations have been previously observed in CaP cell lines (Beheshti et al, 2001) and in patient samples (Cunningham et al, 1996;Erbersdobler et al, 1999;Al-Maghrabi et al, 2001. Little is known about mechanisms driving the generation of excess aberrations during CaP development and progression.…”

“…A total of 100 nuclei per focus of interest were counted for each probe, up to 400 nuclei per patient. Scoring criteria have been described in detail in Al-Maghrabi et al (2001).…”

“…Loss of 8p and gain of 8q were the most frequent changes followed by gain of chromosomes 7, 10q, 16q and 18q (Macoska et al, 1994;Qian et al, 1995;Erbersdobler et al, 1996;Takahashi et al, 1996;Sakr and Partin, 2001). There is increasing evidence that acquisition of numerical and structural chromosomal alterations observed in CaP and HPIN could be a consequence of an underlying process of chromosomal segregation errors, and a more general underlying process of genomic instability (Al-Maghrabi et al, 2001;Beheshti et al, 2001).…”

Bortezomib as a Potential Treatment for Prostate Cancer

“…Mutations to tumor suppressor genes and oncogenes are also evident in established human androgen-independent and androgendependent prostate cancer cell lines, as well as primary prostate cancers and metastases (71)(72)(73). The human prostate cancer cell lines LNCaP, DU145, and PC-3 vary in their expression of important tumor suppressor genes such as p53, retinoblastoma (Rb), and phosphatase/tensin homologue deleted on chromosome 10 (PTEN), but no specific genotype has been assigned to cancer cells with androgen independence or dependence (Table 1).…”

Clinical implications of radiation-induced genomic instability

“…A detailed examination of prostatectomy specimens focused on identification of chromosomal instability associated with areas of high-grade intraepithelial neoplasia (PIN) either within, or separate from, areas of frankly invasive prostate cancer (Al-Maghrabi et al, 2001). Chromosomal instability was measured by interphase FISH analysis probing for abnormalities in chromosomes 7, 8, X and Y.…”