Related Experiment Video
Updated: Sep 23, 2026
Establishment of a Clinic-based Biorepository
Published on: May 29, 2017
Overexpression of p53 tumor suppressor protein in porokeratosis
J W Magee1, T H McCalmont, P E LeBoit
1Department of Pathology, University of California, San Francisco.
Background:
p53 is a tumor suppressor nucleoprotein. Mutations of the p53 gene have been found in a variety of malignant neoplasms. Wild-type p53 has a short half-life, possibly only 20 to 30 minutes, and is not present in the nucleus at levels that are detectable with routine immunohistochemical techniques. Mutant p53 has a longer half-life, and is readily detectable with immunoperoxidase staining.
Results:
We studied 17 specimens from patients with either porokeratosis of Mibelli or actinic porokeratosis, using immunoperoxidase staining with an antibody directed against the p53. There was staining of lesional keratinocyte nuclei in 16 of 17 specimens, limited in most cases to the zone between cornoid lamellae. Staining for proliferating cell nuclear antigen was increased above background levels in only six of 13 specimens.
Conclusions:
The finding of p53 immunoperoxidase staining in porokeratosis suggests genetic mutation, as occurs in other cutaneous keratinocytic neoplasms, and the lack of corresponding proliferating cell nuclear antigen expression in many specimens indicates that p53 overexpression is not simply a reflection of increased cellular proliferation.
Related Concept Videos
01:23Negative Regulator Molecules
02:23Abnormal Proliferation
01:12Loss of Tumor Suppressor Gene Functions
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
01:05Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
01:12Loss of Tumor Suppressor Gene Functions
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...