RESUMO
We have previously shown TP16 MTS1/CDK41 gene deletion in more than 50% of a cohort of squamous cell carcinoma of the head and neck (SCCHN) patients using polymerase chain reaction (PCR). We have performed fluorescence in situ hybridization (FISH) on paraffin-embedded SCCHN specimens from the same cohort to identify the deletion of TP16 MTS1/CDK41CDK41gene. Twenty normal and 19 SCCHN specimens were studied. An alpha-satellite DNA probe specific for chromosome 9 and a cosmid probe for the TP16 MTS1/CDK41CDK41gene were used. Of the 19 tumors examined by FISH, 6 had homozygous deletions, 7 were hemizygously deleted, and the remaining 6 showed no evidence of deletion of the TP16 MTS1/CDK41 gene. None of the normal specimens showed TP16 gene deletion. Data obtained from FISH highly correlated with the PCR results for the identification of TP16 MTS1/CDK41 gene deletions. Patients with deletion of the TP16 MTS1/CDK41 gene show a greater tendency toward the development of recurrence and metastasis.
Assuntos
Deleção de Genes , Genes p16 , Neoplasias de Cabeça e Pescoço/genética , Hibridização in Situ Fluorescente/métodos , Neoplasias de Células Escamosas/genética , Adulto , Idoso , Cromossomos Humanos Par 9/genética , Feminino , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Recidiva Local de Neoplasia , Neoplasias de Células Escamosas/patologia , Prognóstico , Fatores de RiscoRESUMO
OBJECTIVES/HYPOTHESIS: Cyclin D1, a cell cycle regulator localized to chromosome 11q13, is amplified in several human tumors including head and neck squamous cell carcinoma (HNSCC). Amplification and/or overexpression of cyclin D1 have been correlated to a poor prognosis. Deletion of the p16 gene, localized to 9p21, has also been observed in a significant proportion of HNSCC. The p16 gene regulates cyclin D1-CDK4 activity and prevents retinoblastoma tumor suppressor gene phosphorylation, thereby downregulating cellular proliferation. Detection of cyclin D1 amplification and p16 deletion using a simple and sensitive method will be valuable for the development of effective treatment modalities for head and neck cancer. STUDY DESIGN: We have used fluorescence in situ hybridization (FISH) to study cyclin D1 amplification and p16 gene deletion in head and neck tumors. Both single- and dual-color FISH were performed. METHODS: Paraffin-embedded tissues from 103 patients with HNSCC were analyzed using genomic DNA probes for cyclin D1 and p16. Dual-color FISH was performed with chromosome 11 or 9 centromeric probes as a control. Twenty-eight of these samples were analyzed for p16 expression by immunohistochemistry. RESULTS: Cyclin D1 amplification was observed in 30% (31/103) of patients, and p16 deletion in 52% (54/103). Lack of p16 expression was observed in 64% (18/28) of patients. There was a good correlation between the deletion of p16 sequences and the loss of p16 expression (P = .008). Amplification of cyclin D1 had a statistically significant association with recurrence, distant metastasis, and survival at 36 months. There was a significant association between p16 deletion and the development of distant metastases. Cyclin D1 amplification and p16 deletion together correlated with recurrence, distant metastasis, and survival. CONCLUSIONS: We demonstrate that FISH is a simple and sensitive method for detecting cyclin D1 amplification and p16 deletion in head and neck cancer. Our results suggest that these two genetic aberrations together portend a poorer outcome than either of the abnormalities alone in head and neck cancer.
