[Specific immunoglobulins G and M in blood serum in retinoblastoma and 'pseudoretinoblastoma']. / Spetsificheskie immunoglobuliny G i M v syvorotke krovi pri retinoblastome i 'psevdoretinoblastomakh'.

Perinatal inflammatory retinal diseases and intrauterine retinal maldevelopments are mistaken for retinoblastoma as often as in 8-16% of cases. AIM: To analyze the infectious status in children with retinoblastoma and pseudoretinoblastoma at different ages. MATERIAL AND METHODS: A total of 47 retinoblastoma suspects aged 4-69 months were enrolled. Pseudoretinoblastoma (inflammatory retinal diseases and intrauterine maldevelopments of the retina) was detected in 14 children (group 1), retinoblastoma - in 33 children (group 2). In each group, two subgroups were identified: 'a' - children under 12 months of age (1a - 5 patients, 2a - 10 patients) and 'b'- children over 12 months of age (1b - 9 patients, 2b - 23 patients). Their blood sera were examined for antibodies to herpes simplex virus types 1 and 2, cytomegalovirus, Epstein-Barr virus, toxoplasma, toxocara, chlamydia, and mycoplasma (enzyme-linked immunosorbent assay). RESULTS: According to serological screening, all patients from group 1a (children under 12 months of age with pseudoretinoblastoma), in contrast to other groups, were infected perinatally with cytomegalovirus infection. All 47 patients were seronegative to toxoplasma. Toxocara infection was identified in children over 12 months of age: in 3 out of 9 patients with pseudoretinoblastoma and in 2 out of 23 patients with retinoblastoma (p>0.05). Markers of Epstein-Barr viral activity were detected only in 3 retinoblastoma children over 12 months of age. CONCLUSION: The results suggest that cytomegalovirus infection plays the leading role in the development of perinatal eye pathology, which, in infants, is clinically similar to retinoblastoma. In children over 12 months of age we found no serological signs that could be regarded as specific of either retinoblastoma, or pseudoretinoblastoma. The only thing worth paying attention to is the activation of Epstein-Barr virus infection in children over 12 months of age with retinoblastoma.

Five DNA tumor viruses undetectable in human retinoblastomas.

Retinoblastoma (RB) is a childhood eye cancer that arises when a retinal cell lacks a functional RB gene. Recent data indicate the transforming proteins of adenovirus, papillomavirus, and the polyomaviruses BK and JC all can bind to the product of the RB gene. Furthermore, adenovirus 12, JC virus, and simian virus 40 are able to induce RB-like tumors in rodents. In view of these findings, 50 human RBs were tested for the presence of five human DNA tumor viruses: adenovirus 12, BK virus, JC virus, and human papillomaviruses 16 and 18. Using the polymerase chain reaction, no viral sequences were detected in 50 RB DNAs. These data provide no evidence that these viruses have an etiologic role in human RB.

High levels of enhanced reactivation of herpes simplex virus in skin fibroblasts from various hereditary cancer-prone syndromes.

The dose response of the enhanced reactivation (ER) of herpes simplex virus type 1 has been studied in UV-irradiated normal human skin fibroblasts and fibroblasts from the following hereditary cancer-prone syndromes: retinoblastoma, aniridia, polyposis coli, neurofibromatosis type 1 and 2, dysplastic nevus syndrome, Von Hippel-Lindau syndrome, multiple endocrine neoplasia type 2, and Bloom's syndrome. Surprisingly, much higher levels of ER were observed in all these genetically heterogeneous hereditary disorders than in normal human skin fibroblasts. These results suggest that loss of one allele of putative tumor suppressor genes may activate cellular processes that result in the induction of the ER response, and they support our previous observation suggesting that ER may somehow be related to the process of carcinogenesis (P. J. Abrahams et al., Cancer Res., 48: 6054-6057, 1988).

Genomic DNA analysis of rat retinal tumor induced by adenovirus type 12.

To elucidate the pathogenesis of human retinoblastoma, we investigated the genomic expression in retinal tumors induced by human adenovirus type 12 in rats, using various DNA probes. Seven rats received a single intraocular inoculation of concentrated virus fluid within 24 hours after birth. Intravitreous tumors were induced in two out of seven animals (28.5%) within 30 to 64 days after the inoculation. A remarkably uniform histologic feature, i.e., neuroblastic cells in association with Homer-Wright pseudorosettes, was present in all cases. The adenovirus-related oncoprotein gene E1A and human retinoblastoma susceptibility gene were detected in the tumors by Southern blot hybridization. In situ hybridization analysis demonstrated expression of adenovirus type 12 E1A gene in the inner granular layer of the retina. It was suggested that integration of adenovirus type 12 E1A fragment with the host genome and expression of the gene were required for induction of this tumor.

Structural characterization of neovascularization in adenovirus-12-induced retinal tumor.

In order to elucidate a relationship between newly formed micro-blood vessels in retinal tumor and blood-retina barrier, we studied light and electron microscopic and immunohistochemical findings of newly-formed micro-blood vessels in human adenovirus 12-induced retinoblastoma-like tumors in rats. In contrast to other experimentally induced tumors of the central nervous system, there was no evidence of formation of Weibel-Palade bodies and endothelial gaps in this experimental model of retinoblastoma, but factor VIII related antigen was evidently demonstrated. Increased pinocytotic vesicles suggested that the vast majority of these blood vessels did not retain the normal physiological barrier functions. The basement membrane of the micro-blood vessels was poorly developed. The morphological characteristics of the micro-blood vessels of this retinoblastoma-like tumor were compared with those of human retinoblastoma and other experimentally induced tumors of the central nervous system.

Chemotherapeutic response of tumor derived from human adenovirus 12--induced retinal tumor cell line in syngeneic CDF (F 344) rats.

The effect of two anticancer agents, vincristine (VCR) and cyclophosphamide (CTX), on an established cell line (EXP-5) derived from human adenovirus serotype 12 (Ad 12)--induced retinal tumor was studied in vitro and in vivo. VCR at a concentration of 5 and 10 micrograms/ml of culture medium and CTX at 50 and 100 micrograms/ml suppressed growth in vitro. EXP-5 cells were transplanted into the vitreous of 56 inbred CDF (F 344 strain) rats. The implants grew almost exclusively as intravitreous tumors within one month. When the tumor was full grown in the vitreous, VCR and CTX were administered intravenously, singly or in combination, on a schedule based on the protocol CCG-961 for localized unilateral retinoblastoma, Reese-Ellsworth group 5. At a dosage of 0.05 mg/kg, VCR was effective in reducing tumor size; at a dosage of 5 mg/kg, CTX did not reduce tumor size. Combined VCR/CTX therapy induced reduction of about two thirds in tumor size in 2 of 10 treated animals; in all 10 animals, the tumor became morphologically less distinct during the course of treatment although some characteristic features remained. Cytotoxic tumor changes (necrosis, fibrous proliferation, cell transformation, and bizarre giant cells) were observed in all treated animals. This model used the EXP-5 cell line grown in the vitreous, thereby providing a potential tool for evaluating growth and chemotherapeutic responsiveness of retinoblastoma.

The adenovirus type 12 - mouse cell system: permissivity and analysis of integration patterns of viral DNA in tumor cells.

The integration patterns of persisting adenovirus type 12 (Ad12) DNA were analyzed in two Ad12-induced tumors of Balb/c and CBA/J mice and in one tumor cell line derived from an Ad12-induced retinoblastoma of C3H origin. In all three tumors the Ad12 genome was integrated colinearly and various copy numbers of viral DNA were found. Analysis of the Ad12 integration patterns revealed relatively simple offsize band patterns regardless of Ad12 copy numbers. The degree of methylation at the 5'-CCGG-3' sites in the inserted Ad12 genome was determined using the isoschizomeric restriction endonuclease pair HpaII and MspI. Methylation was rather incomplete in the primary tumor tissues but almost complete in the retinoblastoma line carried in culture for many passages. The levels of expression of the viral genome in the Balb/c tumor and in the retinoblastoma line were determined by in vitro translation of RNA isolated from these cells and selected with appropriate restriction endonuclease fragments of Ad12 DNA. In both instances the 59 K, 19 K, and 17 K proteins of the E1b region were expressed. Proteins of the E1a region appeared very faint in the size class between 22 K and 42 K. The permissivity of Ad12 and the replication of Ad12 DNA in mouse cells were investigated by blotting restricted DNA from cells soon after, and a long time after, infection and by hybridization with 32P-labeled Ad12 DNA. Neither primary mouse kidney cells nor the established L929 mouse cell line supported viral DNA replication. These results raise the question to what extent host cell factors determine Ad12 DNA replication in mammalian cells.

Retinal tumor induced in the baboon by human adenovirus 12.

Three of 21 newborn baboons injected intraocularly with human adenovirus type 12 developed an intravitreal mass 12 to 36 months later. Two of the masses were indistinguishable from human retinoblastoma, a retinal tumor that afflicts children. To our knowledge this is the first time a retinoblastoma-like tumor has been induced experimentally by adenovirus type 12 in a nonhuman primate.