December 2002
Volume 43, Issue 13
Free
ARVO Annual Meeting Abstract  |   December 2002
Disruption of the Rb and p53 Tumor Suppressor Checkpoints Occurs Early in the Transformation of Uveal Melanocytes
Author Affiliations & Notes
  • J Harbour
    Center for Ocular Oncology Dept of Ophthalmology & Visual Sciences Washington University Sch of Med St Louis MO
  • L Worley
    Center for Ocular Oncology Dept of Ophthalmology & Visual Sciences Washington University Sch of Med St Louis MO
  • J Wu
    Center for Ocular Oncology Dept of Ophthalmology & Visual Sciences Washington University Sch of Med St Louis MO
  • Footnotes
    Commercial Relationships   J. Harbour, None; L. Worley, None; J. Wu, None. Grant Identification: NIH Grants K08 EY00382-01 and R01 Ey13169-01 (JWH)
Investigative Ophthalmology & Visual Science December 2002, Vol.43, 1831. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      J Harbour, L Worley, J Wu; Disruption of the Rb and p53 Tumor Suppressor Checkpoints Occurs Early in the Transformation of Uveal Melanocytes . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1831.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Abstract: : Purpose: A large number of genetic alterations have been described in uveal melanoma, including cytogenetic changes on chromosomes 3, 6, 8, 13 and 17, and molecular abnormalities of Myc, cyclin D, p16, Rb, p53, HDM2, Bcl-2 and other oncoproteins. However, it has been difficult to distinguish the mutations that are important in the pathogenesis of uveal melanoma from those that represent late secondary changes. To study the early mutational events in the development of uveal melanoma, we examined molecular changes in uveal melanocytes undergoing transformation in culture. Methods: Cultured normal uveal melanocytes at passage 8 underwent crisis, with 99% of melanocytes undergoing cell death, followed by repopulation of the colony with a rapidly growing clone of immortalized melanocytes that were established in nude mice as growing tumors. Pre-crisis and transformed melanocytes were compared by Affymetrix microarray analysis (mRNA expression) and western blot analysis (protein expression) for Rb, p16, cyclin D1, p53, ARF, HDM2, and Myc. Induction of apoptosis by an anti-HDM2 transducible peptide was measured by MTS viability assay. Results: Transformed uveal melanocytes demonstrated an in vitro growth rate 5-fold higher than pre-crisis cells, and they formed tumors in nude mice with a doubling rate of 10 days. Transformed melanocytes demonstrated increased mRNA expression of cyclin D1 (3.4-fold) and HDM2 (2.4-fold), increased protein expression of HDM2, and hyperphosphorylation of Rb. No changes in protein expression levels were detected for Rb, p16, p53, ARF, or Myc. An anti-HDM2 peptide preferentially induced apoptosis in transformed melanocytes compared to pre-crisis cells. Conclusion: Overexpression of HDM2 and cyclin D1 may be two of the earliest mutations in the transformation of uveal melanocytes. These alterations, which occur frequently in primary uveal melanomas, may cooperate in malignant transformation. Cyclin D1 disrupts the Rb cell cycle checkpoint by hyperphosphorylating and inactivating Rb, whereas HDM2 may allow deregulated melanocytes to evade the p53 apoptotic checkpoint by inhibiting p53. These changes, which appear to occur earlier than those reported in Myc, p16, and other oncoproteins, could provide a rational basis for molecular therapy in this eye cancer.

Keywords: 464 melanoma • 610 tumors • 463 melanocytes 
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×