Androgen receptor amplification is associated with increased cell proliferation in prostate cancer.

Mechanisms of prostate cancer progression during hormonal therapy and the pathobiologic consequences of androgen receptor (AR) gene amplification are inadequately known. To further investigate the hypothesis that AR gene amplification is associated with increased cell proliferation, we analyzed 123 paraffin-embedded prostate cancer specimens from men who experienced tumor relapse during androgen withdrawal therapy. We used fluorescence in situ hybridization to quantify AR gene copy number and Ki-67 immunohistochemistry to determine cell proliferation.

Kruppel-like factor 6 germ-line mutations are infrequent in Finnish hereditary prostate cancer.

Purpose: Recently, Kruppel-like factor 6 gene (KLF6) has been shown to be inactivated in up to 77% of prostate carcinomas. KLF6 has an important role in regulating cell growth and differentiation. The function and high mutation frequency in sporadic prostate carcinomas make KLF6 an attractive candidate for prostate cancer predisposition and, therefore, DNA samples from 69 Finnish prostate cancer families were analyzed for KLF6 mutations.

Androgen receptor mutations in high-grade prostate cancer before hormonal therapy.

Androgen action is mediated through androgen receptor (AR), which appears to undergo structural and functional alterations during prostate cancer (CaP) progression. AR mutations have been infrequently reported in CaP before hormonal therapy, but in untreated, advanced tumors AR mutations are suggested to be more common. To investigate the frequency of AR mutations in aggressive CaP before hormonal therapy, we have analyzed AR coding region for aberrations in 21 paraffin-embedded prostate carcinoma samples (14 primary tumors, 7 metastases) of poor histologic differentiation.

Germline mutation analysis of the androgen receptor gene in Finnish patients with prostate cancer.

Purpose: Steroid hormones, particularly androgens, are suspected to have a major role in prostate carcinogenesis. Since androgen receptor mediates androgenic effects on cells and recent studies suggest that the androgen receptor gene is a putative prostate cancer susceptibility locus, we screened the coding region of the androgen receptor gene for germline mutations using the genomic DNA of patients with prostate cancer.

Materials And Methods: DNA samples from 38 patients with early onset prostate cancer and 36 from Finnish prostate cancer families showing no male-to-male transmission of prostate cancer were analyzed for mutations in the androgen receptor gene using single strand conformation polymorphism analysis and subsequent sequencing.

Deletion, mutation, and loss of expression of KLF6 in human prostate cancer.

Kruppel-like factors (KLFs) are a group of transcription factors that appear to be involved in different biological processes including carcinogenesis. In a recent study, KLF6 was reported as a tumor suppressor gene in prostate cancer because of its frequent loss of heterozygosity (LOH) and mutation as well as functional suppression of cell proliferation. Loss of chromosomal locus spanning KLF6 is relatively infrequent in other published studies of prostate cancer, however.

Androgen receptor gene alterations in Finnish male breast cancer.

Mutations in the androgen receptor (AR) gene have been suggested to predispose to male breast cancer (MBC). Studies on MBC patients have not been based on the mutation screening of the entire coding region of the AR and the number of subjects has been small. Therefore, some AR gene alterations may have remained undetected.

Pattern of somatic androgen receptor gene mutations in patients with hormone-refractory prostate cancer.

Progression to hormone-refractory growth of prostate cancer has been suggested to be mediated by androgen receptor (AR) gene alterations. We analyzed AR for mutations and amplifications in 21 locally recurrent prostate carcinomas treated with orchiectomy, estrogens, or a combination of orchiectomy and estramustine phosphate using fluorescence in situ hybridization, single-strand conformation polymorphism, and DNA sequence analyses. Amplification was observed in 4 of 16 (25%) and amino acid changing mutations was observed in 7 of 21 (33%) of the tumors, respectively.

Defining the region(s) of deletion at 6q16-q22 in human prostate cancer.

Deletion of the long arm of chromosome 6 (6q) frequently occurs in many neoplasms, including carcinomas of the prostate and breast and melanoma, suggesting the location of a tumor-suppressor gene or genes at 6q. At present, however, the region of deletion has not been well defined, and the target gene of deletion remains to be identified. In this study, we analyzed 44 primary prostate cancers with 16 polymorphic markers for loss of heterozygosity (LOH) by using PCR-based techniques.

Androgen receptor alterations in prostate cancer relapsed during a combined androgen blockade by orchiectomy and bicalutamide.

Mechanisms of prostate cancer (CaP) recurrence during a combined androgen blockade (CAB) are poorly understood. Previously, the role of androgen receptor (AR) gene mutations underlying the CAB therapy relapse has been raised. To investigate the hypothesis that AR gene aberrations are involved in CAB relapse, 11 locally recurrent CaP samples from patients treated with orchiectomy and bicalutamide were analyzed for copy number changes and DNA sequence alterations of the AR gene by fluorescence in situ hybridization and single-strand conformation polymorphism, respectively.

Chromosomal changes in locally recurrent, hormone-refractory prostate carcinomas by karyotyping and comparative genomic hybridization.

The genetic mechanisms of prostate cancer recurrence during hormonal therapy are largely unknown. So far, data from conventional karyotype analysis on hormone-refractory prostate carcinomas have not been published, mainly because of the difficulties in obtaining fresh hormone-refractory prostate carcinoma samples and getting metaphases from them. Here, we have studied chromosomal changes in 12 locally recurrent, hormone-refractory prostate carcinomas using karyotyping and CGH that revealed genetic aberrations in all tumors.

Association of E-cadherin germ-line alterations with prostate cancer.

In our recent cancer registry-based study, the incidence of gastric carcinoma was increased up to 5-fold in male relatives of early-onset prostate cancer (PCA) patients. This association may reflect the influence of genetic factors predisposing individuals to both tumor types. Germ-line mutations of the CDH1 gene at 16q have recently been associated with familial gastric cancer.

Loss of heterozygosity and lack of mutations of the XPG/ERCC5 DNA repair gene at 13q33 in prostate cancer.

Background: Three regions of chromosome 13 were previously identified for having loss of heterozygosity (LOH) in human prostate cancer. One of them, at 13q33, was defined by LOH at markers D13S158 and D13S280. The XPG/ERCC5 gene, a DNA repair gene that when mutated in the germline leads to xeroderma pigmentosum, has been mapped to 13q33, within one megabase of D13S158 and D13S280.

Three distinct regions of allelic loss at 13q14, 13q21-22, and 13q33 in prostate cancer.

Chromosome 13 is one of the most frequently altered chromosomes in cancer, including carcinoma of the prostate. Two known tumor suppressor genes, RB1 and BRCA2, map to chromosome 13; however, recent reports suggest that unknown genes on 13q are more likely to be involved in the development of prostate cancer. In order more fully to define the genetic changes on chromosome 13 in prostate neoplasms, we analyzed 27 polymorphic microsatellite markers spanning the q arm for loss of heterozygosity in 40 primary tumors and in metastases from 11 other patients who died of prostate cancer.

PTEN/MMAC1 is infrequently mutated in pT2 and pT3 carcinomas of the prostate.

Deletion of the q23-24 region of human chromosome 10 is one of the most frequent genetic alterations in prostate cancer, suggesting that inactivation of a tumor suppressor gene in this region is involved in the development or progression of this carcinoma. A candidate gene, PTEN/MMAC1, has been identified from this chromosomal region; mutations of this gene have been found in various advanced tumors and cell lines including those of prostate cancer. To further define the role of PTEN/MMAC1 in the development of prostate cancer and its spectrum of genetic alterations, we analysed 40 pT2 or pT3 prostate tumors for allelic loss, mutations, and homozygous deletions using PCR-based methods.

Genetic alterations in prostate cancer cell lines detected by comparative genomic hybridization.

Recent studies have identified several chromosomal regions that are altered in prostate cancer. However, the specific genes affected are, in most of the cases, not known. Cancer cell lines could provide a valuable resource for cloning of genes that are commonly affected in cancer.

Consistent genetic alterations in xenografts of proximal stomach and gastro-esophageal junction adenocarcinomas.

The genetic alterations underlying the development of gastric and gastro-esophageal carcinoma remain largely undefined. DNA copy number changes were determined by comparative genomic hybridization in eight xenografts of proximal gastric and gastro-esophageal junction adenocarcinomas of the intestinal type. All tumors exhibited DNA copy number changes, with a total of 139 changes detected (range, 11-24 per tumor; mean = 17), indicating numerous and widespread alterations within these cancers.

Androgen receptor gene amplification: a possible molecular mechanism for androgen deprivation therapy failure in prostate cancer.

Progression of prostate cancer during endocrine therapy is a major clinical problem, the molecular mechanisms of which remain poorly understood. Amplification of the androgen receptor (AR) gene was recently described in recurrent prostate carcinomas from patients who had failed androgen deprivation therapy. To evaluate the hypothesis that amplification of the AR gene is a cause for the failure of androgen deprivation therapy in prostate cancer, we studied whether AR amplification leads to gene overexpression, whether the amplified AR gene is structurally intact, and whether tumors with AR amplification have distinct biological and clinical characteristics.

Androgen receptor gene amplification in a recurrent prostate cancer after monotherapy with the nonsteroidal potent antiandrogen Casodex (bicalutamide) with a subsequent favorable response to maximal androgen blockade.

Objective: We recently found amplification of the androgen receptor (AR) gene in approximately 30% of locally recurrent prostate carcinomas from patients treated by conventional androgen deprivation (castration) therapy, whereas none of the untreated primary prostate tumors showed this amplification. This suggests that AR gene amplification was selected during androgen deprivation therapy. The present case study represents our initial approach to evaluate the role that AR amplification may play in therapy resistance after other forms of endocrine therapy.

Genetic changes associated with the acquisition of androgen-independent growth, tumorigenicity and metastatic potential in a prostate cancer model.

Genetic changes underlying the progression of human prostate cancer are incompletely understood. Recently, an experimental model system that resembles human prostate cancer progression was developed based on the serial passage of an androgen-responsive, non-tumorigenic LNCaP prostate cancer cell line into athymic castrated mice. Six different sublines, derived after one, two or three rounds of in vivo passage, sequentially acquired androgen independence and tumorigenicity as well as metastatic capacity.

Chromosomal abnormalities in cutaneous T-cell lymphoma and in its premalignant conditions as detected by G-banding and interphase cytogenetic methods.

The etiology of cutaneous T-cell lymphomas (CTCL) is unknown. We studied the pattern of chromosomal abnormalities with G-banding and interphase in situ hybridization methods in blood mononuclear cells in 17 patients representing the different phases of CTCL or the premalignant condition, parapsoriasis en plaque, and in 10 control persons. We used biotinylated centromere-specific probes with fluorescent detection (FISH) for chromosomes 1, 11, 8, and 17 and similar, enzymatically detectable, digoxigenin-labeled probes for chromosomes 1, 6, 12, 17, and 18.

c-erbB-2 in astrocytomas: infrequent overexpression by immunohistochemistry and absence of gene amplification by fluorescence in situ hybridization.

Recent studies suggest that aberrations of c-erbB-2 may be involved in astrocytic brain tumours. We screened immunohistochemically c-erbB2 protein (p185) expression in 94 astrocytic grade 1-4 neoplasms of the brain. The amplification of the c-erbB-2 oncogene was investigated in protein overexpression cases by dual colour fluorescence in situ hybridisation (FISH).

Analysis of genetic changes underlying local recurrence of prostate carcinoma during androgen deprivation therapy.

The molecular mechanisms and genetic changes that lead to the progression of prostate cancer during endocrine therapy are poorly characterized. Here, paired specimens from both untreated primary tumors and from local recurrences were collected from 10 prostate cancer patients treated by conventional androgen deprivation therapy. The genetic progression of the tumors was studied by using interphase fluorescence in situ hybridization and chromosome-specific probes.

In vivo amplification of the androgen receptor gene and progression of human prostate cancer.

Overexpression of amplified genes is often associated with the acquisition of resistance to cancer therapeutic agents in vitro. We have identified a similar molecular mechanism in vivo for endocrine treatment failure in human prostate cancer which involves amplification of the androgen receptor (AR) gene. Comparative genomic hybridization shows that amplification of the Xq11-q13 region (the location), is common in tumours recurring during androgen deprivation therapy.