Expression of the functional cone phototransduction cascade in retinoblastoma

Richard Hurwitz, Emil Bogenmann, Ramon L. Font, Vien Holcombe, Dorothy Clark

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


Retinoblastoma is a malignant intraocular tumor that primarily affects small children. These tumors are primitive neuroectodermal malignancies, however some of them show morphologic evidence of differentiation into photoreceptors. Phototransduction cascades are a series of biochemical reactions that convert a photon of light into a neural impulse in rods and cones. The components of these cascades are uniquely expressed in photoreceptors and, although functionally similar, distinct components of these cascades are expressed in rods and cones. Using HPLC anion exchange chromatography, Western blot analysis, and specific monoclonal and polyclonal antibodies, we found that the cone but not the rod cGMP phosphodiesterase is functionally expressed in all six primary retinoblastomas examined and in three continuous retinoblastoma cell lines. Morphologic evidence of differentiation did not correlate with the expression of the enzyme. Furthermore, GTP analogues could activate the phosphodiesterase activity suggesting that an intact phototransduction cascade is present in the tumors. The presence of the cone phototransduction cascade in retinoblastoma confirms that this tumor has biochemically differentiated along the cone cell lineage.

Original languageEnglish (US)
Pages (from-to)1872-1878
Number of pages7
JournalJournal of Clinical Investigation
Issue number6
StatePublished - Jun 1990


  • cGMP cascade
  • G-protein
  • Phosphodiesterase
  • Photoreceptor
  • Vision

ASJC Scopus subject areas

  • Medicine(all)


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