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  • Key words Protein farnesylation inhibitor  (1)
  • estrogen  (1)
  • p53 transformation  (1)
  • 1
    ISSN: 1432-0843
    Keywords: Key words Protein farnesylation inhibitor ; Human prostate tumors ; Efficacy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: These studies sought to evaluate the antitumor properties of an inhibitor of ras functionality, L-744,832, which acts at the level of its associated protein farnesyltransferase. Methods: Studies were carried out to measure the effects of L-744,832 alone and in combination with paclitaxel (PTXL) against TSU-PR1, DU-145 and PC-3 human prostate tumors xenografted to NCR-nu1 (AT) mice. Tumor-bearing mice were treated on a schedule of daily for 5 days ×2 or 3 with the MTD of L-744,832 and every 3–4 days ×4 with the MTD of PTXL starting 3–5 days after tumor implantation. Tumor volume in millimeters (4/3πr3) was measured 3–5 days after cessation of treatment and the increase in tumor volume in treated and control groups compared. Statistical analysis was carried out by the Chi-squared test. Results: L-744,832 at its MTD markedly inhibited the growth of all three tumors (T/C for increase in tumor mass varied from 11% to 15% and inhibition of growth had a rapid onset (within 1–2 days) and was independent of ras gene status. Estimated tumor doubling times were 8–12-fold greater in treated animals than in control animals. Treatment with L-744,832 for as long as 3 weeks had no untoward effects on the mice as determined by gross examination or necropsy. Administration of L-744,832 with this same dose and schedule potentiated the growth-inhibitory effect of PTXL at its MTD and induced some regression of TSU-PR1 with no obvious deleterious effects on the mice. Conclusions: L-744,832 could be safely administered over a protracted period of time to mice at doses which were markedly inhibitory to the growth of three human prostate tumor xenografts and in combination with PTXL was also well tolerated and brought about some regression of the TSU-PR1 tumor. Overall, these results suggest that L-744,832 could be clinically useful for long-term treatment of early-stage prostate cancer in patients and as an adjunct to cytotoxic therapy for late stages of this disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7217
    Keywords: breast cancer ; oncogenes ; p53 transformation ; temperature sensitive mutant ; tumor suppressors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One common step in the malignant progression of a wide variety of human cancers seems to be inactivation of the p53 gene, via point mutation or deletion or both; or overexpression of mutated protein with dominant transforming activity. This study shows a suppressive effect of wild type p53 on the growth of human breast cancer cells. Introduction of wild type p53 versus mutant into five human breast cancer cell lines containing mutant p53 resulted in a marked reduction in colony formation. Two of these were transfected with human wt p53 expression vectors and the other three were infected with retroviruses packaging human wt p53, both showing similar reduction in the number of surviving colonies, suggesting a role for wt p53 in suppression of breast cancer cell growth. Direct evidence for growth suppression was obtained by introduction of the temperature sensitive p53Val135 into Hs578T human breast cancer cells containing a mutant p53. This murine mutant allele p53Val135 functions as an oncogene at 37° C and as a tumor suppressor at 32° C. The cell line generated was strongly growth inhibited at the restrictive temperature (31.5° C), at which temperature the suppressor form is expressed. This inhibition of proliferation was reversible upon a temperature upshift. Analysis of the cell cycle distribution shows these growth suppressed cells to be inhibited in the G1 phase of the cell cycle. Thus wt p53 may have an important role in breast cancer tumorigenesis.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0730-2312
    Keywords: breast cancer ; growth factors ; estrogen ; IGF-I ; TGF ; PDGF ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We describe studies on human breast cancer in which it is shown that specific growth factors (IGF-I, TGFα, PDGF) are secreted by human breast cancer cells and likely to be involved in tumor growth and progression. These activities are regulated by estradiol in hormone-dependent breast cancer and secreted constitutively by hormone-independent cells. These growth factor activities can induce the growth of hormone-dependent cells in vivo in athymic nude mice. Hormone-dependent breast cancer cells also secrete TGFβ, a growth-inhibitory substance, when treated with antiestrogens. TGFβ functions as a negative autocrine growth regulator and is responsible for some of the growth-inhibitory effects of antiestrogens.
    Type of Medium: Electronic Resource
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