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Updated: Aug 14, 2026
Reconstruct Human Retinoblastoma In Vitro
Published on: October 11, 2022
Expression of p27(KIP1) and cell proliferation in human retina and retinoblastoma
Satoru Kase1, Kazuhiko Yoshida, Kazuhiro Ohgami
1Department of Ophthalmology and Visual Sciences, Hokkaido University Graduate School of Medicine, N15 W7, Kita-ku, Sapporo 060-8638, Japan.
Background:
Retinoblastoma is a rare cancer of the eye, in which biallelic inactivation of the retinoblastoma gene is a hallmark. Although retinoblastoma protein (Rb) and p27(KIP1) block the cell cycle transition from G1- to S-phase, the interaction has not been confirmed in vivo. The aim of this study was to examine the correlation between the expression of p27(KIP1) and cell proliferation in human retina and retinoblastoma.
Materials And Methods:
Human retinoblastoma, surgically removed, was fixed by 4% paraformaldehyde. Then, paraffin-embedded tissue sections were examined using immunohistochemistry with anti-p27(KIP1) and anti-proliferating cell nuclear antigen (PCNA) antibodies.
Results:
Retinoblastoma tissue was adjacent to the normal retina in which tumor cells with homogeneous nuclei proliferated and it was impossible to identify the layer structure of the inner nuclear layer (INL) and the outer nuclear layer (ONL). In normal retina, PCNA-positive nuclei were not observed, whereas nuclear immunoreactivity for PCNA was detected in a variety of tumor cells. Many p27(KIP1)-positive nuclei were detected in INL and ONL, while p27(KIP1) immunoreactivity was not detected in retinoblastoma cells.
Conclusion:
The correlation between disappearance of p27(KIP1) and induction of proliferation activity suggests that functional loss of Rb leads to down-regulation of p27(KIP1) and uncontrolled retinal cell proliferation.
Insights
In retinoblastoma, the protein p27(KIP1) disappears, leading to uncontrolled cell proliferation. This suggests a link between the loss of the retinoblastoma gene (Rb) and increased tumor growth in the eye.
Area of Science:
- Ophthalmology
- Oncology
- Molecular Biology
Background:
- Retinoblastoma is a rare eye cancer characterized by the inactivation of the retinoblastoma gene.
- The retinoblastoma protein (Rb) and p27(KIP1) are known cell cycle inhibitors, but their in vivo interaction in retinoblastoma is unclear.
Purpose of the Study:
- To investigate the relationship between p27(KIP1) expression and cell proliferation in human retina and retinoblastoma.
Main Methods:
- Immunohistochemistry was used to analyze p27(KIP1) and proliferating cell nuclear antigen (PCNA) expression in surgically removed retinoblastoma tissues.
- Paraformaldehyde fixation and paraffin embedding were employed for tissue section preparation.
Main Results:
- Normal retina showed p27(KIP1) expression but no PCNA-positive cells, indicating minimal proliferation.
- Retinoblastoma cells exhibited PCNA-positive nuclei, signifying proliferation, but lacked p27(KIP1) immunoreactivity.
- Tumor cells in retinoblastoma displayed homogeneous nuclei and disrupted retinal layer structure.
Conclusions:
- The absence of p27(KIP1) correlates with increased proliferation in retinoblastoma.
- Functional loss of the retinoblastoma gene (Rb) likely causes decreased p27(KIP1) levels, promoting uncontrolled retinal cell proliferation.
Related Concept Videos
01:20The Retinoblastoma Gene
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
01:23Negative Regulator Molecules
02:34Inhibition of Cdk Activity
02:23Abnormal Proliferation