Classical examples are the Rb-1 gene associated with the development of retinoblastoma and the p53 gene, which is associated with a wider range of neoplasms, including breast cancer.
LOH affecting p53 was observed in 8 of 17 (47%) of heterozygous patients, while LOH of Rb and the mcc/apc locus was observed in 9 of 27 (33%) and 13 of 39 (33%) of heterozygotes, respectively.
Analysis of clinical breast cancer samples showed that most of the cells contained two copies of the RB1 gene, even when restriction fragment length polymorphism analysis showed loss of heterozygosity (LOH) at the RB1 locus.
In addition, we studied the c-myc gene for rearrangements by Southern blotting and assessed expression of the retinoblastoma (Rb) and p53 genes by immunostaining.
In addition, we studied the c-myc gene for rearrangements by Southern blotting and assessed expression of the retinoblastoma (Rb) and p53 genes by immunostaining.
Human malignant gliomas (glioblastomas and anaplastic astrocytomas) are the most frequent brain tumors and are associated with a variety of genetic alterations including retinoblastoma (RB) and p53 gene mutations, loss of interferon alpha and beta (IFNA, IFNB) genes and lack of O6-methylguanine-DNA methyltransferase (MGMT) expression.
Human malignant gliomas (glioblastomas and anaplastic astrocytomas) are the most frequent brain tumors and are associated with a variety of genetic alterations including retinoblastoma (RB) and p53 gene mutations, loss of interferon alpha and beta (IFNA, IFNB) genes and lack of O6-methylguanine-DNA methyltransferase (MGMT) expression.
All tumors showed immunoreactivity with NSE, whereas GFAP staining was limited to the perivascular glial tissue confirming the essential neuronal nature of retinoblastoma cells.
This element overlaps the basal transcription unit of the Rb promoter, suggesting that p53 suppresses Rb transcription through inhibition of the basal promoter activity.
ESD in conjunction with RB polymorphism would be useful in prenatal and presymptomatic diagnosis, as well as in carrier detection in informative pedigrees.
By using a sensitive immunoperoxidase method, increased P-glycoprotein was detected in five multidrug-resistant and two selectively plant alkaloid-resistant retinoblastoma cell lines and in the intraocular and metastatic tumors from which they were derived.
While pp60c-src was found in most tumors studied, the neuronal form was restricted to neuroblastomas (23 of 27) and retinoblastomas (3 of 3) and could not be detected in the other childhood tumors.
In order to evaluate the role of RB1 in cancer, the wild type RB1 gene was introduced into the RB1-deleted breast cancer cell line MDA-468-S4 and retinoblastoma cell lines WERI-Rb1 and Y-79.
With regard to tumors of central nervous system origin, bcl2 expression was absent from most medulloblastomas but was detected at moderate to low levels in a retinoblastoma and some glioblastoma multiforme cell lines.