Allelic loss on chromosome 6Q in primary prostate cancer.

Molecular genetic analyses of human prostate cancer (CaP) has revealed frequent loss of specific chromosome regions suggesting the presence of putative tumor suppressor gene(s) (TSG) on these chromosome loci whose inactivation may play a role in prostate tumorigenesis. To understand the role of 6q alterations in CaP, we have undertaken a comprehensive analysis of proximal 6q. Genomic DNA from tumor and normal prostate tissues from radical prostatectomy specimens of 38 patients were analyzed by polymerase chain reaction (PCR) for 13 polymorphic microsatellite loci on 6q. Allelic losses of 1 or more polymorphic loci were detected in 11 of 38 patients (29%). Six of 11 tumors showing any 6q deletion were found to have allelic losses at D6S1056 and D6S300 loci. Our results revealed a 1.5 megabase interval between D6S1056 and D6S300 at 6q16.3-21 as the minimal region of deletion, which may contain the putative TSG involved in prostate tumorigenesis. One of the tumor samples demonstrated homozygous deletion at a distal location D6S314 (6q23-24), suggesting another locus potentially associated with CaP. Although the relationship of 6q loss of heterozygosity (LOH) with various clinico-pathologic variables, i.e., cancer recurrence or pathologic stage, did not reveal a statistically significant association, the risk for 6q LOH to non-organ confined (pT3) disease was 5-fold higher than for organ confined disease.

Gold toning improves the visualization of nucleolar organizer regions in paraffin embedded tissues.

A modification of the silver colloid technique for staining nucleoar organizer regions in paraffin embedded tissues is described. This modification involves the application of a gold toning step with subsequent gold reduction, if necessary, following incubation of sections in the standard silver colloid solution. Silver stained nucleolar organizer regions (AgNORs) in toned sections are more sharply delineated when compared to untoned controls. In high grade tumors the addition of the toning step results in significantly higher AgNOR counts due to the ability to discriminate more easily individual AgNORs in argyrophilic aggregates within the nucleus. It is recommended, because of enhanced visualization, that this modification of the silver colloid technique be used in studies involving quantification of AgNORs in tissue sections.

Correlation of nucleolar organizer regions and glandular dysplasia of the stomach and esophagus.

Forty-seven biopsies of gastric mucosa and Barrett esophagus from 32 patients were studied with the argyrophilic nucleolar organizer region method. Twenty-two biopsies were gastric and 25 esophageal. Four showed normal noninflamed mucosa, 14 reactive glandular changes, eight intestinal metaplasia without dysplasia, ten low grade dysplasia with intestinal metaplasia, and 11 high grade dysplasia. The mean number of nucleolar organizer regions was 14.9 for high grade dysplasia, 10.9 for low grade dysplasia, 8.5 for intestinal metaplasia without dysplasia, 6.7 for reactive changes, and 3.9 for normal mucosa. The difference between high grade dysplasia and the other groups was significant (P = 0.004). However, the difference between high and low grade dysplasia was not significant (P = 0.06), and there was an overlap between reactive and high grade dysplastic lesions. We conclude that although nucleolar organizer counts correlate with the degree of dysplasia, the technique is of limited practical use.

Nucleolar organizer regions in seminoma and intratubular malignant germ cells.

Nucleolar organizer regions (NORs), as demonstrated by a silver-colloid staining technique, have been counted in 71 primary testicular seminomas (typical seminoma (TS) 31, high mitotic index seminoma (HMIS) 24, and spermatocytic seminoma (SS) 16) and ten seminomas metastatic to retroperitoneal lymph nodes. Mean NOR counts were 14.36 for TS; 17.66 for HMIS; 10.89 for SS; and 17.70 for metastatic seminoma. Analysis of data using Student's unpaired t-test showed a significant difference between the NOR counts obtained from TS, HMIS, and SS. Furthermore, there was a statistically significant difference between NOR counts in metastatic seminoma when compared with TS and SS but not HMIS. The association between tumor proliferation rates and intranuclear NOR numbers is discussed. In addition to a numerical variation, the NOR distribution throughout the nucleus was noted to be different in SS when compared with the other varieties of seminoma studied. The pattern observed had some features similar to those seen in cells of the spermatogenic series. The NOR technique was also applied to 19 cases of intratubular malignant germ cells (ITMGC). It was shown that these malignant cells were easily identified using this staining method and that the NOR distribution was similar to that seen in TS and HMIS. The mean NOR count in ITMGC was 16.41. This was significantly different from that of TS but not HMIS.