8p22 loss concurrent with 8c gain is associated with poor outcome in prostate cancer.

OBJECTIVES: A critical issue in the management of prostate cancer is the ability to distinguish patients at risk of disease recurrence. The aim of this study was to determine whether specific physical alterations of chromosome 8 may be associated with disease recurrence and poor outcome using postoperative prostate-specific antigen (PSA) values as surrogate end points. METHODS: To test this hypothesis, we examined paired normal and tumor radical prostatectomy tissues from 25 patients with prostate cancer for chromosome 8 alterations using dual fluorescence in situ hybridization with a fluorescein-labeled 8p22-specific (8p) cosmid probe and a rhodamine-labeled 8-centromere-specific (8c) probe. The probes were enumerated in 200 nuclei per tissue. RESULTS: Of the 25 tumors examined, 22 demonstrated distinct classes of genetic alterations, or nuclear types, including disomy for 8p and 8c (1 tumor), loss of 8p and disomy for 8c (10 tumors), or loss of 8p concurrent with gain of 8c (11 tumors). The presence of even a small population of tumor nuclei characterized by the loss of 8p concurrent with the gain of 8c was correlated with poor tumor grade (P = 0.009), preoperative PSA values 11 ng/mL or higher (P = 0.022), high tumor stage (P = 0.086), and detectable, rising postoperative PSA values (P = 0.086). These observations are consistent with the hypothesis that a gain of chromosome 8 is associated with poor outcome in prostate cancer. CONCLUSIONS: 8p loss concurrent with 8c gain may successfully predict disease recurrence and poor clinical outcome before the observation of detectable postoperative PSA values in patients with prostate cancer.

Homozygous and frequent deletion of proximal 8p sequences in human prostate cancers: identification of a potential tumor suppressor gene site.

By using tissue microdissection and polymerase chain reaction (PCR) techniques, we examined 85 prostate tumors that were paired with normal tissues from the same patients for allelic loss at 26 highly polymorphic microsatellite sequences, 21 spanning 8p and 5 localized to 8q. Sixty-four tumors (75%) demonstrated loss of at least one 8p locus. Separate distal and proximal regions of deletion were observed as well as an intervening, staggered breakpoint. A novel region of homozygous deletion of sequences at the D8S87 locus was detected both by multiplex PCR and by fluorescence in situ hybridization within this breakpoint region. These data suggest that a tumor-suppressor gene mapping to proximal 8p is deleted frequently and is likely to be important for tumorigenesis in prostate tumors.

Distinct areas of allelic loss on chromosomal regions 10p and 10q in human prostate cancer.

Utilizing tissue microdissection and PCR techniques, we have examined 35 prostate tumors paired with normal tissues from the same patients for allelic loss at 24 polymorphic loci spanning chromosome 10. Twenty-five tumors (71%) were deleted for at least one chromosome 10 locus. Of the total 35 tumors, 6 (17%) were deleted for 10p loci only, 5 (14%) for 10q loci only, and 14 (40%) were deleted for both 10p and 10q loci. The common region of deletion on 10p included loci D10S211-D10S89-D10S111. Fluorescence in situ hybridization of yeast artificial chromosome probes encompassing these loci demonstrated that the 10p region of deletion maps to 10p11.2. Losses involving 10p loci alone were most common in localized (5/14, 36%) and least common in metastatic (0/8) tumors. The common region of deletion on 10q included loci D10S219-D10S215, consistent with the major region of deletion recently defined for prostate tumors on 10q. Losses involving 10q loci alone were lowest in localized and locally invasive tumors (1/14 and 2/12, respectively) and highest in tumors metastatic to regional lymph nodes (2/8). These results suggest that 10p losses may define less invasive tumors, whereas 10q losses may play a role in the progression to more advanced tumor states in the prostate. Furthermore, this is the first report of allelic loss of a defined region on 10p potentially harboring tumor suppressor gene loci in human prostate cancer.

Evidence for three tumor suppressor gene loci on chromosome 8p in human prostate cancer.

Allelic loss of human chromosome sequences is often equated with inactivation of putative tumor suppressor genes. Loss of sequences on the short arm of chromosome 8 (8p) has been observed in human cancers, especially of 8p22 in prostate tumors. By using PCR analysis of highly polymorphic microsatellite repeat markers at nine 8p loci in 135 tumors, we observed deletion of sequences at 8p22 and at two other proximal deletion domains. These novel deletion domains encompass the NEFL locus and D8S87-ANK1 loci, respectively. These data suggest that three 8p tumor suppressor gene loci may be independently deleted in human prostate cancers.

Fluorescence in situ hybridization analysis of 8p allelic loss and chromosome 8 instability in human prostate cancer.

Cytogenetic and molecular biological studies have demonstrated deletion of sequences that map to the short arm of chromosome 8 (8p) in tumors from several organ systems, including sequences that map within or near 8p22 in human prostate tumors. Recent studies in our laboratory have suggested that deletion of sequences on 8p may be concurrent with alterations in dosage for chromosome 8. In order to further investigate this finding, the present study has applied fluorescence in situ hybridization (FISH) techniques to determine the status of chromosome 8 in prostate tumors that have undergone deletion of sequences at 8p22. Dosage of 8p22 sequences was assayed utilizing unique sequence cosmid DNA probes by FISH and confirmed by amplification of microsatellite sequences by polymerase chain reaction (PCR). Chromosome 8 dosage was assayed by FISH utilizing both unique sequence cosmid probe DNA (specific to the 8q13.1-q13.3 chromosomal region) and pericentromeric probe DNA. FISH analysis of 10 specimens of normal or benign prostatic hyperplasia tissues paired with 9 tumor and one prostatic intraepithelial neoplasia tissues from the same patients for dosage at 8p, 8cen, and 8q, and PCR analysis for dosage at 8p, demonstrated that (a) FISH provided a more precise means of evaluating allelic loss than PCR in prostate tissue; (b) 8p22 sequence losses occurred frequently in prostate tumors; (c) 8p22 sequence losses were most often detected in the absence of 8cen or 8q sequence dosage alterations, although they were sometimes accompanied by gain or loss of 8cen or 8q sequences; and (d) the pattern of 8p22 sequence losses was most often widespread rather than focal. This study is the first to describe FISH analysis of interphase nuclei within tissue sections using cosmid probe DNAs.