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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Urological research 15 (1987), S. 133-138 
    ISSN: 1434-0879
    Keywords: Androgen independent tumor cells ; Prostatic cancer heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Development of androgen-independent prostatic cancer cells from androgen-responsive cells can occur by a variety of mechanisms (e.g., environmental adaptation, multifocal origin, or genetic instability). Regardless of the mechanism of development, however, once androgen-independent cancer cells become present within prostatic cancer, the tumor is no longer homogeneous but is now heterogeneous. Once a prostatic cancer is heterogeneously composed of both androgen-dependent and-independent cancer cells, androgen withdrawal therapy, no matter how complete, cannot be curative. In order to produce cures of such heterogeneous prostatic cancers, hormonal therapy must be combined simultaneously with chemotherapy early in the course of the disease so that all the cancer populations (i.e., androgen-dependent and-independent) can be simultaneously affected within an individual patient.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    World journal of urology 9 (1991), S. 58-63 
    ISSN: 1433-8726
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary An important molecular approach for the study of the complex processes implicated in prostatic carcinogenesis is the determination of steady-state mRNA levels of potentially relevant genes. One important category of these genes are the proto-oncogenes. Previous studies on the involvement of oncogenes in prostatic carcinogenesis, using primary human prostatic tumors, have shown that the ras and myc oncogenes might be related to the progression of this disease. We tested this hypothesis in the Dunning R-3327 rat prostatic cancer model system, which consists of a series of sublines that represent the different stages of tumor progression in prostatic cancer. We could not show a correlation between the expression of the ras and myc proto-oncogenes and the state of progression of the disease. The levels and patterns of expression of other proto-oncogenes, however, might be more useful as markers for malignancy and/or progression of prostatic cancer in rats.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1434-0879
    Keywords: Transitional cell carcinoma ; Tumor progression ; Rat tumor model ; Marker chromosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A cohort of 300 ACI rats was kept under standard laboratory conditions. After 30 months or upon natural death, complete autopsy was performed. In the genitourinary tract four kidney and five bladder tumors were found. Two of these bladder tumors, RBT323 and RBT157, are serially transplantable. In the fifth transplant generation the RBT323 tumor becomes metastatic to the lungs in more than 90% of animals. The metastatic ability of the RBT157 tumor changes from low to intermediate (50% of the rats have lung metastases) in the fourth passage. Histologically, the initial passages of the RBT323 and 157 tumors are grade II transitional cell carcinoma (TCC). The histological pattern of the RBT157 tumor remains essentially unchanged, whereas the RBT323 tumor progresses to a grade III tumor in the third passage. Electron microscopical studies reveal oblong elliptical and round vesicles lined by an asymmetrical unit membrane in the tumor cells, which stresses the urothelial origin of the tumors. Immunohistochemically both tumors show expression of cytokeratin 5, 7, 8 and 18. The progression of the tumors to a metastatic phenotype, however, is not associated with a specific change in the morphological characteristics. Cytogenetic analysis shows that both tumors are peridiploid with few marker chromosomes. Interestingly, both of these independently arising tumors exhibit a loss of chromosome 5. Rat chromosome 5 is syntenic to the major portion of human chromosome 9 (p23-qter). Loss of chromosome 9 is a cytogenetic trait of human superficial TCC, hence the RBT mocel is also in cytogenetic respect similar to human TCC. Two independently arising rat tumor lines that initially resemble superficial TCC both phenotypically and cytogenetically are described. Upon serial transplantation both lines progressed to a more aggressive tumor, albeit to a different extent (highly vs moderately metastatic). Thus this model system may be helpful in the identification of specific markers associated with the progression of superficial bladder cancer.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1433-8726
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Prostate cancer is one of the most commonly diagnosed cancers and is a major cause of cancer death in men. Although the majority of the diagnosed prostate cancers will remain localized and never produce clinical symptoms during the lifetime of the host, a subset of these cancers will progress to a more malignant state requiring therapeutic intervention. Acquisition of metastatic ability by prostatic cancer cells is the most lethal aspect of prostatic cancer progression. Once this has occurred, definitive therapy is required before the initially localized metastatic cells escape from the prostate. At present, metastatic prostate cancer is incurable. Therefore, there is an urgent need to develop molecular markers that can be used to predict the metastatic potential of prostate cancers. Using somatic cell hybridization, we have demonstrated that acquisition of metastatic ability requires both the loss of metastasis-suppressor function(s) and the activation of oncogenes. In further studies using micro-cell-mediated chromosomal transfer, we located genes on human chromosome, 8, 10cen-q23, 11p11.2-13, and 17pter-q23, which, when introduced into rat prostatic cancer cells, are capable of suppressing their metastatic ability without affecting their tumorigenicity or growth rate in vivo. Initially we focused upon the human chromosome 11p11.2-13 region to clone metastasis-suppressor gene(s) positionally. One such gene, termed KAI-1, encodes a membrane glycoprotein. KAI-1 has been mapped to the p11.2 region of human chromosome 11 by fluorescence in-situ hybridization analysis. Expression of KAI-1 has been detected in all normal human tissues thus far tested, including prostate tissue. When introduced into rat metastatic prostatic cancer cells, KAI-1 significantly suppressed the metastasis without affecting the tumor growth rate. KAI-1 expression is high in human normal prostate and benign prostatic hyperplasia but is dramatically lower in cancer cell lines derived from metastatic prostate tumors.
    Type of Medium: Electronic Resource
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