Tissue microarray evidence of association between p16 and phosphorylated eIF4E in tonsillar squamous cell carcinoma.
ABSTRACT Expression of p16 is a marker for human papillomavirus (HPV)-related carcinogenesis in head and neck cancer. The purpose of this study is to determine if p16 immunoreactivity is associated with aberrant expression of components of the PI3 kinase pathway.
A tissue microarray (TMA) was constructed for 46 archived tonsillar squamous cell carcinoma specimens. Clinical demographics of these patients were analyzed, and the TMA was interrogated with antibodies directed against p16, phosphorylated Akt(Ser473), phosphorylated S6(Ser240/244), phosphorylated S6(Ser235/236), phosphorylated 4E-BP1(Thr37/46), phosphorylated eIF4E(Ser209), PTEN, p21, and p53.
There was a significant correlation between history of tobacco abuse (>10 pack/years) and absence of p16 expression (p = .01). Expression of p16 was significantly associated with immunoreactivity of p21 (p = .02), PTEN (p = .02), and phosphorylated eIF4E (p = .03). There was no evidence of association between p16 status and expression of phosphorylated S6, phosphorylated 4E-BP1, or p53.
p16 positive tonsillar squamous cell carcinoma is characterized by expression of phosphorylated eIF4E that may occur via a mammalian target of rapamycin (mTOR)-independent mechanism.
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ABSTRACT: A genetic progression model of head and neck squamous cell carcinoma has not yet been elucidated, and the genetic basis for "field cancerization" of the aerodigestive tract has also remained obscure. Eighty-seven lesions of the head and neck, including preinvasive lesions and benign lesions associated with carcinogen exposure, were tested using microsatellite analysis for allelic loss at 10 major chromosomal loci which have been defined previously. The spectrum of chromosomal loss progressively increased at each histopathological step from benign hyperplasia to dysplasia to carcinoma in situ to invasive cancer. Adjacent areas of tissue with different histopathological appearance shared common genetic changes, but the more histopathologically advanced areas exhibited additional genetic alterations. Abnormal mucosal cells surrounding preinvasive and microinvasive lesions shared common genetic alterations with those lesions and thus appear to arise from a single progenitor clone. Based on these findings, the local clinical phenomenon of field cancerization seems to involve the expansion and migration of clonally related preneoplastic cells.Cancer Research 07/1996; 56(11):2488-92. · 8.65 Impact Factor
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ABSTRACT: The retinoblastoma gene (RB-1) was originally identified as the gene involved in hereditary retinoblastoma. However, RB-1 mutations are found in a number of common mesenchymal and epithelial malignancies. The retinoblastoma protein (pRB) acts as a transcriptional regulator of genes involved in DNA synthesis and cell-cycle control. In this regard, the functional interaction between pRB and the E2F transcription factor family appears to be critical. The pRB-E2F interaction is, in turn, regulated by a pathway that includes cyclin D1, cdk4, and p16. Mutations that affect this pathway have been documented in nearly every type of adult cancer. Thus, perturbation of pRB function may be required for the development of cancer. Insights into the biochemical functions of pRB, and its upstream regulators, may form the basis for the development of novel antineoplastic agents.Journal of Clinical Oncology 12/1997; 15(11):3301-12. · 18.04 Impact Factor
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ABSTRACT: Complete excision of cancer is guided by histologic assessment of surgical margins. Molecular markers may be more sensitive in identifying malignant cells. eIF4E, a eukaryotic protein synthesis initiation factor, is found elevated in all head and neck squamous cell cancers (HNSCC). In a preliminary study using Western blots and a retrospective study using immunohistochemistry, eIF4E elevation in histologically tumor-free surgical margins correlated with a higher local-regional recurrence. We wanted to confirm this hypothesis in a prospective study. Immunohistochemical analysis of surgical margins and tumors with an antibody to eIF4E was performed on all newly diagnosed HNSCC patients who underwent surgical resection for their disease between January 1996 and December 1997. All 65 patients had elevated levels of eIF4E in the tumors. Thirty-six patients (55%) had elevated eIF4E in histologically tumor-free margins, and 20 of these patients (56%) have had local-regional recu rrences. Twenty-nine patients (45%) had no elevation of eIF4E in the margins, and only two of these patients (6.9%) have had recurrences. Cox regression analysis showed that elevated eIF4E in the margins was an independent prognostic factor (P =.009) for recurrence. The Kaplan-Meier curves for the probability of nonrecurrence were significantly different for positive and negative eIF4E margins (P =. 0001, log-rank test). In histologically tumor-free surgical margins, elevated levels of eIF4E predict a significantly increased risk of recurrence. Elevated levels of eIF4E in tumor margins may identify patients who could benefit from additional therapy.Journal of Clinical Oncology 10/1999; 17(9):2909-14. · 18.04 Impact Factor