p53 protein expression in laryngeal squamous cell carcinomas bearing wild-type and mutated p53 gene

p63 in laryngeal squamous cell carcinoma: evidence for a role of TA-p63 down-regulation in tumorigenesis and lack of prognostic implications of p63 immunoreactivity

p63 is a p53-related gene that encodes for multiple mRNA transcripts with (TA-p63) or without (DeltaN-p63) transactivating properties on p53-responsive genes. We evaluated for the first time the prevalence and clinical implications of p63 immunoreactivity (IR) and mRNA expression in laryngeal squamous cell carcinomas (LSCCs). Moreover, we also assessed the relationships between p63 expression and p53 gene status. p63 IR was detectable in the basal cell layers of non-neoplastic epithelium and in the whole thickness of dysplastic epithelium. All the 150 LSCCs analyzed were immunoreactive for p63, with 28 (18.7%) cases showing p63 IR in </=50% of neoplastic cells. DeltaN-p63 mRNA transcripts were detected in all the 23 tumors analyzed, whereas TA-p63 mRNA transcripts were absent in 5 (21.7%) cases. p53 gene mutations were found in 24 (29.2%) of the 82 cases analyzed and p53 IR was found in 58 (53.7%) of the 108 cases analyzed; neither was associated with p63 IR. No significant association was found between p63 IR and patients' survival. Interestingly, down-regulation of TA-p63 mRNA levels was more prevalent in patients with T3-T4 tumors and advanced clinical stage. Although the risk of death for cancer was higher in these patients (40% versus 16.6%), this difference did not reach statistical significance. Our results suggest that abnormal expression of p63 may be involved in the early phases of laryngeal tumorigenesis irrespective of p53 gene status and that TA-p63 mRNA down-regulation, but not p63 IR, may be clinically relevant in patients with LSCC.

Recent advances in the molecular biology of head and neck tumours

Our knowlcwdge about the genetic basis of head and neck tumours is accumulating fast. This article reviews the important advances in this area over the last decade and its implications for the future. Newer aspects of gene therapy, molecular staging and understanding head and neck carcinogenesis on a molecular level are outlined.

Expression of p53 protein and Ki-67 antigen in gingival hyperplasia induced by nifedipine and phenytoin

BACKGROUND

Although it has been thought that drug-induced gingival hyperplasia is not related to tumorigenesis, recent case reports have shown that squamous cell carcinomas may arise in gingival hyperplasia induced by cyclosporin and phenytoin. The possible implications between the pathogenesis of this disease and tumorigenesis have not been elucidated and remain to be studied.

METHODS

We immunohistochemically examined the expression of tumor-related markers such as p53 protein and Ki-67 antigen in 11 hyperplastic gingival tissues induced by nifedipine and phenytoin, as well as 5 control tissues using an avidin-biotin-peroxidase complex method.

RESULTS

Two specimens out of 4 nifedipine-induced and 4 out of 7 phenytoin-induced hyperplastic gingival tissues revealed the expression of p53 protein in the nuclei of epithelial cells, while no expression of p53 protein was observed in the epithelia of the 5 non-hyperplastic control tissues. The immunoreactions against p53 protein showed sporadic distribution in the suprabasal layers of hyperplastic epithelia. The mean percentage of epithelial cells expressing Ki-67 antigen in the hyperplastic gingival tissues was more than 10% higher than that in the controls. The expression of Ki-67 antigen was suppressed in the typical rete pegs deeply elongated into lamina propria of hyperplastic gingival tissues. Intense immunostaining of Ki-67 antigen was found in fibroblasts of hyperplastic gingival tissues, while that of the control tissues was negligible.

CONCLUSIONS

The expression of p53 protein in gingival hyperplasia suggests that the pathogenesis of this disease is involved with impaired DNA, while the growth arrest observed in the hyperplastic epithelia with typically elongated rete pegs as expressed with Ki-67 antigen may prevent the invasive expansion of epithelial cells undergoing DNA damage within gingival tissues and may consequently suppress tumorigenic progression.

Clinical relevance of p53 and bcl-2 protein over-expression in laryngeal squamous-cell carcinoma

We investigated immunohistochemically the clinical relevance of the over-expression of the apoptosis-regulating proteins p53 and bcl-2 in a homogeneous series of 149 laryngeal squamous-cell carcinomas. p53 was over-expressed in 75 cases and bcl-2 in 39 cases. p53 and bcl-2 co-expression was found in 21 cases. p53 and bcl-2 immunoreactivity was significantly associated with poor histological differentiation and lymph-node metastases. Moreover, a significant statistical correlation was found between bcl-2 expression, supraglottic tumor site and advanced disease stage. p53/bcl-2 co-expression was significantly associated with poor differentiation, tumor extension, the presence of lymph-node metastases and advanced clinical stage. Univariate analysis showed that a lower probability of survival was significantly associated with supraglottic site, tumor extension, advanced clinical stage and p53/bcl-2 co-expression, but not with p53 or bcl-2 considered separately. In multivariate analysis, only tumor extension and supraglottic site retained their prognostic value. Our data suggest that clinical staging remains the most reliable predictive indicator of survival in patients with laryngeal carcinoma.

The predictive value of p53, MDM-2, cyclin D1 and Ki67 in the progression from low-grade dysplasia towards carcinoma of the larynx

To evaluate the predictive role of the oncogenes p53, MDM-2 and cyclin D1, and the proliferative marker Ki67, in the progression from low-grade dysplasia to carcinoma of the larynx. We studied immunohistochemically a series of 32 low-grade pre-neoplastic laryngeal lesions, 10 of which progressed to invasive carcinoma. Immunoreactivity in more than 10 per cent of the dysplastic cells was detected in five cases immunostained with anti-p53 (approximately 15 per cent), in two with anti-MDM-2 (approximately six per cent), and 11 with anti-Ki67 antibodies (approximately 34 per cent), whereas none of the cases showed cyclin D1 overexpression. No significant association was found between p53 and MDM-2 immunoreactivity and the evolution to carcinoma; on the contrary, Ki67 expression was detectable in all but one of the 10 cases developing an infiltrative tumour (90 per cent), and in two of the 22 cases that did not progress (approximately nine per cent) (p = 0.01). These findings indicate that immunohistochemical assessment of the proliferative index in bioptic samples of dysplastic laryngeal mucosa may be useful in selecting patients who should undergo a more specific follow-up evaluation.

Pretreatment pathologic prognostic factors in head and neck squamous cell carcinoma

Squamous carcinomas of the head and neck region are a common problem for the otolaryngologist; surgeons are obliged to draw together disparate lines of evidence-from physical examination, pathology, and radiology-to plan optimal therapy for their patients. This article explores some of the ways in which pathologic analysis of a biopsy specimen in the past (determination of extent of invasion and degree of differentiation), present (including an analysis of the pattern of infiltration and the tumor' s DNA content), and, perhaps, the future (possibilities including cytogenetics and analysis of discrete steps in the cell cycle) plays a role in this process.