Human papillomavirus and widespread cutaneous carcinoma after PUVA photochemotherapy.

BACKGROUND: Oral psoralen with UV-A (PUVA) photochemotherapy is known to cause cutaneous malignancies and has been associated with cutaneous immunosuppression. Human papillomavirus infection has also been associated with cutaneous malignancies and with immunosuppressed individuals. We therefore sought evidence of human papillomavirus infection in a patient with a long history of PUVA therapy and multiple cutaneous malignancies. OBSERVATIONS: During a 15-year period, an otherwise healthy patient with psoriasis who had undergone a 10-year course of PUVA photochemotherapy developed 13 squamous cell carcinomas, eight lesions diagnosed as "squamous cell carcinoma vs keratoacanthoma," 14 other keratoacanthomas, six basal cell carcinomas, one melanoma in situ, and 18 other keratinocytic dysplasias. Twenty-two of the 30 lesions tested for human papillomavirus DNA by polymerase chain reaction were positive for type 16/18, including six of the seven basal or squamous cell carcinomas tested. CONCLUSION: We hypothesize that PUVA therapy-induced immunosuppression may play an important role in PUVA-related carcinogenesis by affecting the extent and pathogenicity of human papillomavirus infection.

Mutations in the p53 gene: an early marker of neoplastic progression in ulcerative colitis.

BACKGROUND/AIMS: In long-term extensive ulcerative colitis, aneuploidy occurs earlier and loss of heterozygosity for p53 (p53 LOH) later during histological progression towards carcinoma. This study determined the time of onset of p53 mutation in this progression. METHODS: We developed a rapid, sensitive screening assay for p53 mutations at codon 248. The geographic distribution of this p53 mutation was mapped in two fresh colectomy specimens with mutations of codon 248 (1 cancer, 1 dysplasia) and correlated with patterns of clonal expansion, histological progression, and allelic loss. Numerous samples from throughout both colons were analyzed (216 for histology, 142 for DNA content, 104 for mutation, and 41 for p53 LOH). RESULTS: p53 mutation correlated highly with histological grade and was distributed more extensively than p53 LOH. Mutation, but not LOH, was also found in diploid, nondysplastic colonic mucosa adjacent to dysplastic areas. CONCLUSIONS: These findings suggest that p53 mutation appears to be an early genetic event that precedes p53 LOH. The very close correlation of p53 mutation with aneuploidy (P > 0.0001) emphasizes the role of normal p53 at the G1 checkpoint to help prevent entry of genetically damaged cells into the cell cycle.

Evidence against DNA polymerase beta as a candidate gene for Werner syndrome.

Werner syndrome (WS) is a rare autosomal recessive disorder of humans characterized by the premature onset and accelerated rate of development of several major age-related disorders. An aberration in DNA replication or repair is suggested by the evidence of genome instability. Since the structural gene for DNA polymerase beta maps within the region of the WS mutation on the short arm of chromosome 8 and is involved in both DNA repair and DNA replication, we evaluated its candidacy as the WS gene. Several independent lines of evidence did not support that hypothesis: (1) activity gels showed normal enzyme activity and electrophoretic mobility; (2) nucleotide sequence analysis of the entire coding region failed to reveal mutations (although indicated mistakes in the published sequence); (3) single-strand conformation polymorphism (SSCP) and heteroduplex analyses failed to reveal evidence of mutations in the promoter region; (4) a newly discerned polymorphism failed to reveal evidence of homozygosity by descent in a consanguineous patient; and 5) fluorescence in situ hybridization (FISH) analysis placed the DNA polymerase beta gene centromeric to D8S135 at 8p11.2 and thus beyond the region of peak LOD scores for WS.

Deletion mapping of chromosome 8p in colorectal carcinoma and dysplasia arising in ulcerative colitis, prostatic carcinoma, and malignant fibrous histiocytomas.

Short tandem repeat polymorphism markers on the short arm of chromosome 8 were used to search for loss of heterozygosity (LOH) in colorectal carcinoma and dysplasia complicating ulcerative colitis, in prostatic carcinoma, and in malignant fibrous histiocytoma (MFH). Fifty percent of prostatic carcinomas (13/26), 44% of carcinomas or dysplasias arising in ulcerative colitis (7/16), and 30% (4/12) of MFH cases showed LOH for markers on 8p. Detailed mapping demonstrated variability in the size of the chromosomal region showing LOH; however, the data suggest a common 30-centimorgan region of LOH on chromosome 8p between the LPL locus and pter in colorectal and prostatic cancers. In addition, LOH was observed on 8p in both high-grade and low-grade dysplasia in ulcerative colitis, indicating that LOH on 8p may occur at an early stage of neoplastic development in this disorder. In contrast, MFH cases exhibited LOH for marker D8S87, which has been identified as being near the putative Werner's syndrome locus. These results suggest that a tumor suppressor gene, located on the distal portion of chromosome 8p, exists in common for prostatic and colorectal carcinomas, and a second tumor suppressor gene may exist linked to the Werner's syndrome locus.

Development of human papillomavirus-associated Buschke-Löwenstein penile carcinoma during cyclosporine therapy for generalized pustular psoriasis.

Buschke-Löwenstein-type giant penile condyloma developed in a human immunodeficiency virus-negative, 25-year-old man after 4 years of intermittent cyclosporine therapy (5 mg/kg/day) for pustular psoriasis. Microscopic examination showed multifocal areas of invasive squamous cell carcinoma. Dot blot analysis of amplified polymerase chain reaction products with primers directed at the L1 region demonstrated signals for several human papillomavirus genotypes, including human papillomavirus type 16, that correlated with different histologic patterns consisting of verrucous and bowenoid changes and invasive carcinoma. This case conforms to the enhanced risk of cutaneous carcinogenesis from either papillomavirus infection or chronic actinic damage that has become evident in patients with organ allografts and cyclosporine therapy.

The polymerase chain reaction. Method and applications in dermatopathology.

Since it was first reported in 1985, the polymerase chain reaction (PCR) has revolutionized the way molecular studies are performed, and has developed into one of the most powerful tools in molecular pathology. By use of a cyclic change of temperature, a specific and exponential in vitro amplification of a target DNA sequence can be achieved within hours. As a template for PCR reactions, total genomic DNA is used; this can be readily extracted from clinical specimens. Very low quantities of DNA, as well as DNA degraded by fixation, can also be used as a template for PCR reactions, allowing formalin-fixed, paraffin-embedded tissue to become amenable to detailed molecular analysis. Sequences specific for certain viruses and other microorganisms, as well as molecular marker sequences associated with various types of human cancer, can be readily detected in paraffin-embedded tissue sections. The methodology of PCR, along with various applications in dermatopathology, are reviewed.

Squamous cell carcinoma of the scrotum associated with human papillomaviruses.

A 53-year-old man presented with recurrent squamous cell carcinoma, and dysplasia of the scrotum and penis. Risk factors included psoralen and ultraviolet radiation therapy for psoriasis, and x-ray therapy for primary lymphoma of the groin. Three different human papillomavirus types were documented using the polymerase chain reaction in distinct anatomical areas. The scrotal carcinoma was associated with human papillomavirus type 18, while regions of dysplasia contained either type 18, 16 or 6/11. Diagnosis of squamous dysplasia and carcinoma of the scrotum in men with psoriasis is complicated by chronic active inflammation, and molecular biological methods may be necessary to detect human papillomavirus infected cells.

DNA aneuploidy in colonic biopsies predicts future development of dysplasia in ulcerative colitis.

The objective of the present study was to determine whether abnormal epithelial DNA content (aneuploidy) in colonic biopsy specimens from ulcerative colitis (UC) patients correlated with and predicted histological progression to dysplasia. Aneuploidy was absent in 20 low-cancer risk patients. In 81 high-cancer risk patients aneuploidy correlated significantly with the severity of histological abnormality (negative, indefinite, dysplasia, or cancer). Statistically our data suggest that many more biopsy specimens than are usually taken are needed to detect focal dysplastic lesions. Prospective study of 25 high risk patients without dysplasia revealed 5 with aneuploidy, all of whom progressed to dysplasia in 1-2.5 years, whereas 19 patients without aneuploidy did not progress to either aneuploidy or dysplasia within 2-9 years. Our data indicate that aneuploidy in mucosal biopsy specimens correlates with histological grade and identifies a subset of patients without dysplasia who are more likely to develop it. It was concluded that more frequent and extensive colonoscopic surveillance of this minority subset of high risk patients and less frequent surveillance in the remaining majority may reduce cost and detect more curable lesions.

Neoplastic progression in ulcerative colitis: histology, DNA content, and loss of a p53 allele.

Neoplastic progression in patients with chronic ulcerative colitis (UC) is characterized by the development of epithelial dysplasia, which is accompanied by genetic abnormalities that can be detected by flow cytometric and molecular biologic methods. Distribution of and correlation between histologic abnormalities, DNA content, and loss of heterozygosity for a p53 allele (p53 LOH) in the colons of nine UC patients were analyzed. Loss of a p53 allele was found in 85% (22/26) of biopsy specimens classified histologically as carcinoma, 63% (25/40) of biopsy specimens with high grade dysplasia, and 33% (7/21) of biopsy specimens with low grade dysplasia. Loss of heterozygosity for p53 was also found in 9% (5/57) of biopsy specimens indefinite for dysplasia and in 1/18 biopsy specimens negative for dysplasia, showing that this genetic change may occur early in the histological progression towards carcinoma. Aneuploid DNA contents were more common than p53 LOH in regions with negative, indefinite or low grade dysplastic histology; moreover, p53 LOH was detected only in aneuploid cells and not in diploid epithelium. Aneuploidy alone was not as specific a marker for the concomitant presence of dysplasia or carcinoma in a biopsy sample as aneuploidy combined with p53 LOH. These findings show that aneuploidy may precede both p53 LOH and epithelial dysplasia. Two UC patients' colons contained geographically separated clones of cells with different aneuploidies that also showed loss of different p53 alleles, suggesting that neoplasia may arise within different populations of cells in separate areas of the same colon.

Evolution of the salmonid mitochondrial control region.

To explore the evolutionary nature of the salmonid mitochondrial DNA (mtDNA) control region (D-loop) and its utility for inferring phylogenies, the entire region was sequenced from all eight species of anadromous Pacific salmon, genus Oncorhynchus; the Atlantic salmon, Salmo salar; and the Arctic grayling, Thymallus arcticus. A comparison of aligned sequences demonstrates that the generally conserved sequence elements that have been previously reported for other vertebrates are maintained in these primitive teleost fishes. Results reveal a significantly nonrandom distribution of nucleotide substitutions, insertions, and deletions that suggests that portions of the salmonid D-loop may be under differential selective constraints and that most of the control region of these fishes may evolve at a rate similar to that of the remainder of their mtDNA genomes. Maximum likelihood and Fitch parsimony analyses of 9 kb of aligned salmonid sequence data give evolutionary trees of identical topology. These results are consistent with previous molecular studies of a limited number of salmonid taxa and with more comprehensive, classical analyses of salmonid evolution. Predictions from these data, based on a molecular clock assumption for the mtDNA control region, are also consistent with fossil evidence that suggests that species of Oncorhynchus could be as old as the Middle Pliocene and would have thus given rise to the extant Pacific salmon prior to about 5 or 6 million years ago.

Frequent loss of a p53 allele in carcinomas and their precursors in ulcerative colitis.

Allelic deletions of the p53 gene previously were demonstrated by Southern hybridization to occur in high frequency in sporadic colon carcinomas and in a variety of other human tumors. We have examined the frequency of allelic loss of the p53 gene in carcinoma and dysplasia arising in patients with chronic ulcerative colitis who are heterozygous for the codon 72 polymorphism in exon 4 of the p53 gene. Cells derived from carcinoma and dysplasia specimens from 10 patients who were heterozygous at this locus were sorted by flow cytometry on the basis of DNA content. The p53 exon 4 region was amplified from diploid and aneuploid populations, via a polymerase chain reaction (PCR), and digested with BstUI. Three of three carcinomas, four of six dysplasias, and one patient who was indefinite for dysplasia demonstrated evidence of allelic loss of the p53 gene. Seven of ten cases of sporadic colon carcinoma, analyzed for comparative purposes, exhibited loss of a p53 allele. These results demonstrate that PCR analysis, followed by restriction endonuclease digestion of a polymorphic locus, can provide a rapid, definitive method for analyzing loss of heterozygosity in small numbers of cells from colonic mucosa. Such loss precedes cancer in ulcerative colitis and can be present in its earliest histologically identifiable precursor.

Targeted gene walking polymerase chain reaction.

We describe a modification of a polymerase chain reaction method called 'targeted gene walking' that can be used for the amplification of unknown DNA sequences adjacent to a short stretch of known sequence by using the combination of a single, targeted sequence specific PCR primer with a second, nonspecific 'walking' primer. This technique can replace conventional cloning and screening methods with a single step PCR protocol to greatly expedite the isolation of sequences either upstream or downstream from a known sequence. A number of potential applications are discussed, including its utility as an alternative to cloning and screening for new genes or cDNAs, as a method for searching for polymorphic sites, restriction endonuclease or regulatory regions, and its adaptation to rapidly sequence DNA of lengthy unknown regions that are contiguous to known genes.

Frequency and spectrum of c-Ki-ras mutations in human sporadic colon carcinoma, carcinomas arising in ulcerative colitis, and pancreatic adenocarcinoma.

Sporadic colon carcinomas, carcinomas arising in chronic ulcerative colitis, and pancreatic adenocarcinomas have been analyzed for the presence of c-Ki-ras mutations by a combination of histological enrichment, cell sorting, polymerase chain reaction, and direct sequencing. Although 60% (37/61) of sporadic colon carcinomas contained mutations in codon 12, only 1 of 17 specimens of dysplasia or carcinoma from ulcerative colitis patients contained c-Ki-ras mutations, despite a high frequency of aneuploid tumors. In contrast, a higher percentage (16/20 = 80%) of pancreatic adenocarcinomas contained mutations in c-Ki-ras 2, despite a lower frequency of DNA aneuploidy in these neoplasms. Moreover, the spectrum of mutations differed between sporadic colon carcinoma, where the predominant mutation was a G to A transition, and pancreatic carcinomas, which predominantly contained G to C or T transversions. These results suggest that the etiology of ras mutations is different in these three human neoplasms.

The oligomer extension "hot blot": a rapid alternative to Southern blots for analyzing polymerase chain reaction products.

We report a modification of a liquid hybridization method that serves as a rapid, sensitive alternative to Southern hybridization for the analysis of polymerase chain reaction (PCR) products. An aliquot of the completed PCR is mixed with an internally nested, end-labeled oligonucleotide probe, and one cycle of PCR is performed. The products are electrophoresed, dried and analyzed by autoradiography. The method is significantly more sensitive than standard Southern hybridization methods, is equally specific, requires as little as 1-10 picograms of probe and results can be obtained in less than an hour. The procedure is equally useful for identifying products in multiplex PCRs or single-stranded PCRs.

Comparative analysis of human papillomavirus detection by polymerase chain reaction and Virapap/Viratype kits.

Cervical samples from 270 women referred by area physicians were analyzed for the presence of human papillomavirus (HPV) types 6, 11, 16, and 18 by the polymerase chain reaction (PCR) followed by Southern hybridization. Samples from 154 patients were concurrently analyzed by a commercial filter hybridization technique (Virapap and Viratype Kits, Life Technologies, Bethesda Research Labs, Gaithersburg, MD). The sensitivity of the Southern blot procedure combined with PCR was significantly higher than that of the Virapap and Viratype methods. HPV was detected in 67% of women who had positive results for dysplasia by PCR and in 47% by the Virapap method. HPV types 16/18 were found more commonly than types 6/11 in every diagnostic category. More than one HPV type was detected in 12% of HPV-positive patients. The prevalence of HPV in cytologically negative or indefinite patients as measured by PCR was 22% and 40%; in contrast, by the Virapap method, these values were 7% and 10%. These results demonstrate that PCR combined with Southern hybridization provides a higher level of sensitivity than methods that use hybridization without amplification of HPV DNA and also show that the prevalence of HPV is highest in cytologically positive smears.

c-Ki-ras mutations in chronic ulcerative colitis and sporadic colon carcinoma.

Mutations in the first exon of the c-Ki-ras protooncogene were analyzed in carcinomas and dysplasias from patients with sporadic colon cancer and chronic ulcerative colitis by a combination of histological enrichment, cell sorting, polymerase catalyzed chain reaction, and direct sequencing. In contrast to sporadic colon carcinomas, where 52% (11 of 21) contained mutations in codon 12, only 1 of 28 samples of ulcerative colitis associated carcinoma or dysplasia contained a c-Ki-ras mutation, despite the presence of aneuploid cell populations. These results suggest that a different genetic pathway for tumor progression may exist between sporadic colon carcinoma and carcinomas arising in chronic ulcerative colitis.

Flow cytometric analysis of malignant pleural mesotheliomas.

Forty-six cases of malignant pleural mesothelioma were analyzed for histologic subtype, DNA content, and cell cycle characteristics. Sixty-five percent of cases were diploid in DNA content, with intermediate to low proliferative rates. Thirty-one nonmesothelial malignant neoplasms of the lung, of histologic types most easily confused with malignant mesothelioma, were also examined. In contrast to the mesotheliomas, 85% of these nonmesothelial malignant neoplasms of the lung were aneuploid; the aneuploid neoplasms exhibited higher mean proliferative rates (S = 10.6%) than diploid nonmesothelial neoplasms of the lung (S less than 6%). Unlike most malignant neoplasms, mesotheliomas most often display diploid DNA contents and low proliferative rates despite their clinically aggressive behavior.

Mutations in the KRAS2 oncogene during progressive stages of human colon carcinoma.

A series of colon carcinomas, adenomas, and adjacent tissues were analyzed for ploidy alterations and mutations in KRAS2. To increase the sensitivity for identifying mutations, we used histological enrichment, cell sorting, and DNA amplification by the polymerase-catalyzed chain reaction followed by direct DNA sequence analysis. Of the 40 carcinomas analyzed, 27 contained aneuploid cells and 26 contained mutations at the first position of codon 12 of KRAS2. Of the 12 adenomas studied, 4 contained aneuploid cells and 9 contained the same mutation at codon 12. In both adenomas and carcinomas, mutations were identified in both diploid and aneuploid cells. In some cases, regions of histologically benign mucosa adjacent to the carcinoma contained mutations. These combined results suggest that mutations in KRAS2 occur early in the development of human colon carcinoma, before change in ploidy, and that these mutations exist in diploid cells from which an aneuploid subpopulation arises. Furthermore, mutations may exist in histologically normal mucosa in regions adjacent to carcinoma, suggesting that a field of genetically abnormal mucosa may surround these tumors.

Analysis of c-Ki-ras mutations in human colon carcinoma by cell sorting, polymerase chain reaction, and DNA sequencing.

We have analyzed colon carcinomas by a combination of histological enrichment, cell sorting, polymerase chain reaction, and direct sequencing of the c-Ki-ras-2 gene. DNA was chemically extracted from 50-microns sections of paraffin-embedded colon carcinomas and amplified in vitro, and mutations were documented directly by DNA sequencing. Enrichment for tumor cells was obtained histologically and by sorting nuclei on the basis of DNA content differences. Mutations in codon 12 were present in both aneuploid and diploid subpopulations of sorted carcinomas, suggesting that these mutations precede ploidy alterations in the progression of these neoplasms. We have demonstrated the feasibility of utilizing DNA from tissues treated with different fixatives, including methyl carnoys, formalin, and Hollande's solution. This procedure allows one to retrospectively reconstruct the temporal relationship between the occurrence of mutations and sequential morphological changes during tumorigenic progression.

Evidence for differences in the mechanism of cell cycle arrest between senescent and serum-deprived human fibroblasts: heterokaryon and metabolic inhibitor studies.

It has previously been shown that serum-deprived, early passage quiescent human diploid fibroblastlike (HDFL) cells are able to inhibit cycling cells from entry into DNA synthesis upon cell fusion. We have found that the degree of inhibition of DNA synthesis in the heterokaryon correlates with the duration of serum deprivation, which is consistent with the suggestion that serum-deprived cells may enter progressively deeper stages of G0 as they increase their time in quiescence. In contrast to fusions with senescent cells, in heterokaryons between serum-deprived early passage and cycling young cells transient inhibition of protein synthesis with cycloheximide or inhibition of RNA synthesis with 5-6-dichloro-1-beta-D-ribofuranosyl benzimidazole (DRB) did not stimulate nuclear [3H]-thymidine incorporation. These results suggest that differences may exist in the mechanisms responsible for inhibiting cell cycle progression in senescent vs early passage quiescent HDFL cells.