Article
Expression of INK4A cell cycle proteins P14 and P16 in benign and malignant head and neck tumors
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Published: | September 22, 2005 |
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The INK4a-ARF locus, located on chromosome 9p21, encodes two functionally distinct tumor suppressor proteins, p14ARF and p16INK4a. Those are characterized by different promoter and exon 1 regions spliced to a common exon 2 in different reading frames.The proteins play major roles in the tumor suppressor pathways centered around p53 and pRb.
We analysed the expression of p14, p16, and p53 in adenoid cystic carcinomas (n=7), adenocarcinomas (n=5), cylindrical cell carcinomas (n=4) as well as pleomorphic adenomas (n=5) and inverted papillomas (n=8) of the head and neck.
Protein expression was detected by conventional immunohistochemistry and tyramide signal amplified immunohistochemistry.
In all of the malignant samples, a complete loss of p14 could be identified. 20% of the pleomorphic adenomas and 42% of the inverted papillomas showed distinct cytoplasmic accumulation of the marker, however.
100% of the adenoid cystic carcinomas had obviously lost p53 expression, whereas the protein could be detected in all adenocarcinoma samples.
The INK4a proteins, p14 and p16, could solely be found in the cytoplasm, but p53 was located in the nucleus.
Although the number of tumors investigated was small, certain expression patterns could be derived from this study. To date, there is no comparable data in the literature.
Furthermore, tyramide signal amplification turned out to be a refined method to analyse protein levels in tissue sections.