Immunohistochemical analysis of cell cycle-associated proteins p16, pRb, p53, p27 and Ki-67 in oral cancer and precancer with special reference to verrucous carcinomas

Verrucous carcinoma of the axilla: case report and review

BACKGROUND

Verrucous carcinoma, a variant of squamous cell carcinoma, is distinct from squamous cell carcinoma in morphology and behavior. It preferentially occurs on the oropharyngeal mucosa, the urogenital mucosa, and the soles. In contrast to its malignant clinical picture, the tumor grows locally invasive but is histologically benign and metastasizes rarely.

METHODS

We report the uncommon occurrence of a large verrucous carcinoma on apparently uninvolved skin in the right axilla in a 47-year-old male.

RESULTS

Histologic examination reveals a cauliflower-like tumor consisting of deep invaginated epidermal proliferation with rabbit burrow-like, keratin-filled sinus formations; the basement membrane, however, remains intact. Immunohistology showed positivity for pancytokeratin (KL-1) and cytokeratin (CK) 18 and negativity for CK7, and assessment of the proliferative activity of the tumor cells revealed low percentage of Ki-67 expression. Furthermore, there were only scattered cells expressing p53 or bcl-2. Polymerase chain reaction excluded the presence of human papillomavirus. After complete excision, no signs of recurrence occurred over a follow-up period of three years.

CONCLUSION

Verrucous carcinoma should be distinguished from typical squamous cell carcinoma. The clinicopathological features, differential diagnosis, and therapy are discussed here together with the molecular biologic aspects of the tumor.

Survivin, a potential early predictor of tumor progression in the oral mucosa

Survivin is a recently described apoptosis inhibitor selectively over-expressed in most tumors. Immunohistochemistry was used to investigate a potential role of survivin as an early predictor of malignant transformation in precancerous and cancerous lesions of the oral cavity. Survivin was present in 10/30 cases (33%) of oral precancerous lesions without malignant progression, and in 15/16 cases (94%) of oral precancerous lesions evolved into full-blown squamous cell carcinoma. Tumors that progressed from these precancerous lesions retained widespread survivin positivity (100%). Variations among group means were highly statistically significant (p < 0.001). No significant correlation was found between survivin expression and the degree of dysplasia. High expression of cytoplasmic/nuclear survivin is an early event during oral carcinogenesis and may provide a useful tool for the identification of precancerous lesions at higher risk of progression into invasive carcinoma.

p16(INK4A) immunohistochemical overexpression in premalignant and malignant oral lesions infected with human papillomavirus

Human papillomavirus (HPV) is believed to promote the oncogenic process, and the correlation between viral oncoproteins and dysfunction of p16(INK4A) tumor suppressor protein in oral lesions is controversial. To test the hypothesis that anogenital HPV types participate in disruption of the regulation of p16(INK4A) suppressor protein in oral lesions, we analyzed 46 oral biopsy specimens for the presence of HPV 6/11 and 16/18 by in situ hybridization (ISH) and for p16(INK4A) expression by immunohistochemistry (IHC). Eighteen (39%) of the 46 oral lesions were HPV-positive and 28 (61%) were HPV-negative. HPV 6/11 DNA was found in 5 (11%) and HPV 16/18 in 13 (28%) of 46 biopsies. Nine of the 18 HPV-positive oral lesions (50%), assessed by catalyzed signal amplification coupled to ISH (CSA-ISH), gave high-intensity p16(INK4A) immunostaining. Focal and diffuse patterns were observed in 11/13 (77%) lesions with HPV 16/18, focal immunopositivity in 3/5 (80%) with HPV 6/11, and negative or sporadic p16-labeling in 18/28 (64%) without the presence of HPV DNA. These results showed a strong association between overexpression of p16 protein and malignant oral lesions, mainly those infected by HPV 16/18. We can conclude that high-risk HPV types are associated with p16 overexpression, and p16 may serve as a biomarker in oral cancer related to high-risk HPV infection.

Immunohistochemical study of syndecan-1 down-regulation and the expression of p53 protein or Ki-67 antigen in oral leukoplakia with or without epithelial dysplasia

BACKGROUND

Leukoplakia is an oral pre-cancerous lesion that sometimes develops into squamous cell carcinoma. Therefore, leukoplakia with epithelial dysplasia is useful for studying carcinogenesis at the cellular level. The purpose of this study was to evaluate a potential association between the loss of syndecan-1 expression and the expression of p53 protein and Ki-67 antigen, and to identify reliable markers for predicting malignant changes in oral leukoplakia with epithelial dysplasia.

METHODS

Changes in the expression of syndecan-1, p53, and Ki-67 were examined immunohistochemically in 43 cases of oral leukoplakia with or without epithelial dysplasia. The subjects were categorized as: none, 13 cases; mild dysplasia, 5 cases; moderate dysplasia, 17 cases; and severe dysplasia, 8 cases. The expression of these molecules in normal oral epithelia (22 cases) was also investigated.

RESULTS

Strong syndecan-1 expression was observed on the surface of keratinocytes in normal epithelium. Immunopositivity was lost gradually as the extent of epithelial dysplasia increased. In normal epithelium, p53 and Ki-67 appeared mainly in the basal cell layer, while they were more widely distributed in leukoplakia. Specifically, significant changes were observed in the labeling index of p53 and Ki-67 in leukoplakia as epithelial dysplasia progressed from mild to moderate or severe.

CONCLUSION

Our results reveal that overexpression of p53 protein and Ki-67 antigen, and down-regulation of syndecan-1 expression in the lower part of the epithelium, are associated with dysplastic changes. Therefore, the down-regulation of syndecan-1 expression may be the most important reliable marker for dysplastic changes.

Co-expression of p16(INK4A) and laminin 5 gamma2 by microinvasive and superficial squamous cell carcinomas in vivo and by migrating wound and senescent keratinocytes in culture

The high frequency of mutation, deletion, and promoter silencing of the gene encoding p16(INK4A) (p16) in premalignant dysplasias and squamous cell carcinomas (SCC) of epidermis and oral epithelium classifies p16 as a tumor suppressor. However, the point during neoplastic progression at which this protein is expressed and presumably impedes formation of an SCC is unknown. Induction of p16 has been found to be responsible for the senescence arrest of normal human keratinocytes in culture, suggesting the possibility that excessive or spatially abnormal cell growth in vivo triggers p16 expression. We examined 73 skin and oral mucosal biopsy specimens immunohistochemically to test this hypothesis. p16 was not detectable in benign hyperplastic lesions, but instead was expressed heterogeneously in some dysplastic and carcinoma in situ lesions and consistently at areas of microinvasion and at superficial margins of advanced SCCs. p16-positive cells in these regions coexpressed the gamma2 chain of laminin 5, identified previously as a marker of invasion in some carcinomas. Normal keratinocytes undergoing senescence arrest in culture proved to coordinately express p16 and gamma2 and this was frequently associated with increased directional motility. Keratinocytes at the edges of wounds made in confluent early passage cultures also coexpressed p16 and gamma2, accompanying migration to fill the wound. These results have identified the point during neoplastic progression in stratified squamous epithelial at which the tumor suppressor p16 is expressed and suggest that normal epithelia may use the same mechanism to generate non-dividing, motile cells for wound repair.

Eyelid verrucous carcinoma

PURPOSE

To report a case of verrucous carcinoma (VC) that presented as an eyelid mass on the right eye.

CASE REPORT

A 66-year-old man developed a slow-growing eyelid lesion on the lateral canthus of the right eye. The tumor was firm, well-defined, sessile, acuminate, and exuded foul-smelling fluid.

RESULTS

Excisional biopsy revealed a VC. The patient remains asymptomatic.

CONCLUSIONS

VCs are extremely rare eyelid tumors. This clinicopathological entity is a low-grade variant of squamous cell carcinoma that occurs mainly in the intraoral, genitogluteal, and plantar areas. A role of human papillomavirus (HPV) in these tumors has been recently identified. VCs characteristically show locally aggresive growth. This is the second case reported in the literature on the eyelid. VC should be considered in the differential diagnosis of eyelid tumors.

Squamous cell carcinoma arising in a psoriatic nail bed: case report with discussion of diagnostic difficulties and therapeutic options

We describe a squamous cell carcinoma arising from a psoriatic nail bed. The tumour had a verrucous surface and was very well differentiated, raising the possibility of early verrucous carcinoma. Occurrence of any type of squamous carcinoma in this site and background is extremely rare. Particular diagnostic and therapeutic questions arise in this unusual setting. We discuss the aetiology and diagnostic differentiation from other nail bed squamoproliferative lesions, particularly so-called subungual keratoacanthoma. We also discuss therapeutic options, including Moh's surgery and retinoids.

Prognostic factors in betel and tobacco related oral cancer

Paucity of well-defined prognostic molecular markers severely hampers prediction of the clinical course of squamous cell carcinoma (SCC) of oral cavity. The aim of the study was to evaluate the prognostic significance of impairments in the expression of proteins involved in cell cycle regulation and locoregional spread in oral SCC of habitual betel and tobacco chewers. A prospective study was performed in 105 betel and tobacco consumers with oral SCCs during the period 1988-1999, to evaluate the prognostic relevance of impairments in the expression of proteins involved in cell cycle regulation and locoregional spread. Alterations in the expression of p53, pRb, p16, MDM2, p21, and Ets-1 proteins were determined by immunohistochemical analysis in formalin fixed, paraffin embedded tissue sections from oral SCCs. Analysis of multiple molecular biological factors showed overexpression of p53 in 69/105 (66%) cases, MDM2 in 72/105 (69%) cases, p21 in 57/105 (54%) cases and Ets-1 in 64/105 (61%) cases. Loss of pRb was observed in 58/105 (55%) cases and p16 loss was observed in 72/105 (69%) cases. Interestingly, multivariate analysis revealed loss of pRb as the most significant predictor of advanced tumour stage [P=0.001; Odd's Ratio (OR)=3.5] and overexpression of Ets-1 protein was an independent risk factor for lymph node metastasis (OR: 10.1; P<10(-6)). Multiple logistic regression models showed that pRb loss [Hazard's Ratio (HR): 3.93] and p53 overexpression (HR: 2.97) may serve as adverse prognosticators for disease free survival of the patients. The data demonstrate multiple impairments in p53/MDM2/p21/Ets-1 and p16/pRb pathways in betel and tobacco related oral tumourigenesis.

Aberrant expression of pRb, p16, p14ARF, MDM2, p21 and p53 in stage I adenocarcinomas of the lung

Cancers are always associated with cell cycle abnormalities. To clarify the cell cycle abnormalities present in lung adenocarcinomas, various cell cycle regulatory proteins of both the pRb and p53 pathways were studied immunohistochemically in 50 cases of stage I adenocarcinoma of the lung. In regard to the pRb pathway, most adenocarcinomas showed frequent expression of both p16 and pRb proteins, and aberrant expression in the pRb pathway was observed in about one-quarter of stage I adenocarcinomas. In regard to the p53 pathway, the frequency of immunohistochemical positivity was 8% for p14ARF, 64% for MDM2, 20% for p53 and 24% for p21. In this pathway, the immunohistochemical profile of p14ARF-negative/MDM2-positive/p53-negative is characteristic of stage I adenocarcinoma of the lung. An inverse relationship was found between MDM2 and p53 protein and was associated with the differentiation status of stage I adenocarcinoma of the lung. Our results suggest that the disruption of the pRb and p53 pathways is frequently observed in the early stages of lung adenocarcinoma and might play an important role in the growth and differentiation of adenocarcinoma of the lung.

Differential expression of ras signal transduction mediators in verrucous and squamous cell carcinomas of the upper aerodigestive tract

CONTEXT

ras gene mutations and expression of its gene product have been described in verrucous and squamous cell carcinomas. Other downstream signal-transduction mediators, extracellular signal-regulated kinases 1 and 2 (ERK-1 and ERK-2) and Raf-1, have not yet been as extensively studied.

OBJECTIVE

To determine patterns of expression of ERK-1, ERK-2, and Raf-1 in verrucous and squamous cell carcinomas of the upper aerodigestive tract.

DESIGN

Seventeen verrucous carcinomas and 10 squamous cell carcinomas of the upper aerodigestive tract were examined for the immunohistochemical expression of ERK-1, ERK-2, and Raf-1 product.

RESULTS

Raf-1 expression was intensely expressed in the most basal portions of the epithelium in verrucous carcinomas, but was minimally expressed in the suprabasalar areas. Anti-Raf-1 staining of the squamous cell carcinomas was diffuse and patchy throughout the tumor cells and was weak in intensity. There was no geographic preference of staining. The cytoplasmic expression of both ERK-1 and ERK-2 was predominantly negative in the most basal layers of the epithelium in the verrucous carcinomas, but was positive in the suprabasalar region of the epithelium. Immunohistochemical expression of ERK-1 and ERK-2 in the squamous carcinomas was diffuse throughout the tumor.

CONCLUSION

There is strong correlation of the geographic expression of these mediators of ras signal transduction in verrucous and squamous carcinomas, but the cause of these differences remains unclear at present. The expression of these mediator proteins may have potential for diagnosis, as well as in understanding the biologic behavior of these lesions.

Altered p53 expression in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer: correlation with human papillomaviruses?

Renal transplant recipients are prone to numerous benign and malignant skin lesions. Previous work in the authors' laboratory has determined that the human papillomavirus may be the viral aetiology of these skin lesions. The p53 tumor-suppressor gene is the most frequently mutated gene in a wide range of human cancers. Here the authors describe an immunohistochemical study to evaluate the expression of p53 in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer. The effect of p53 mutations on the expression patterns observed were examined by polymerase chain reaction-single strand conformation polymorphism analysis and direct cycle sequencing. The expression of the p53-regulated cyclin-dependant kinase inhibitor p21Waf1/Cip1 and Mdm2 was also examined in p53-positive cells. The expression of p53 in benign and malignant lesions was found to be markedly different. p53 was expressed in only 40% (6/15) of viral warts analyzed. The expression was confined to the basal layer both in the lesion and in adjacent normal skin, and the level of expression was low and only in a small number of cells (<10%). Of the cutaneous squamous cell carcinomas analyzed, 60% (9/15) showed p53 expression. Two different patterns of expression were observed. Basal layer expression in both the invasive tumor and adjacent normal skin was observed in 50% of the p53-positive squamous cell carcinomas; in the remaining 50%, p53 was expressed diffusely throughout the invasive tumor and in the basal layer of adjacent normal skin. The level of expression was high and in a large number of cells. Polymerase chain reaction-single strand conformation polymorphism analysis revealed that only one of the squamous cell carcinomas expressing p53 harbored a p53 mutation and that the accumulated p53 in the remaining tumors was wild type. No Mdm2 or p21Waf1/Cip1 expression was detected in the p53-positive squamous cell carcinomas, indicating that although the accumulated p53 is stable, it does not function effectively as a transcriptional activator. This represents a novel p53 phenotype in cutaneous squamous cell carcinoma. In addition, no correlation was seen between the presence and absence of human papillomavirus and p53 expression.

Aberrant expression of pRb, p16, p14ARF, MDM2, p21 and p53 in squamous cell carcinomas of lung

Expression of cell cycle regulatory proteins in both the RB and p53 pathways was investigated in 50 cases of squamous cell carcinoma (SCC) of the lung using immunohistochemical techniques. Abnormality of pRb and p16 expression was seen at the frequencies of 16% and 78%, respectively, and appeared to be in a reciprocal relationship. On the other hand, strong and diffuse p53 immunoreactivity was seen in 60% of SCCs. MDM2 and p14ARF expressions were each observed in about half of the cases of SCC and were not significantly associated with strong p53 immunoreactivity. Statistical analysis revealed that p14ARF expression was significantly correlated with both p16 and MDM2 expression. Moreover, strong p53 expression was not correlated with the expression of p21. In comparing clinicopathological status with the immunohistochemical results, lack of p16 immunoreactivity was observed in the elderly group (over 65 years) as compared with the younger group (less than 65 years). Strong p53 expression was frequently observed in higher stages of SCC, with the developing tumor located in the central field of the lung. Similarly, the frequency of p14ARF expression was high in centrally developed SCC, but low in SCC developed in the periphery. These results suggest that disruption of the RB and p53 pathways is a frequent event in SCC, and that abnormal expression of p16 and p53 plays a more critical role than that of pRB, p14ARF and MDM2 in the development of SCC of the lung.

Detection of HPV in Japanese and Chinese oral carcinomas by in situ PCR

Human papillomavirus (HPV) is established as the cause of almost 100% of cervical carcinomas. However, the association of HPV with oral squamous cell carcinomas (SCCs) is less well understood. We examined the prevalence of HPV in oral SCCs in samples of Japanese and Chinese populations. Using in situ polymerase chain reaction (PCR) analysis (MY09 and MY11 consensus primers), HPV was detected in the nucleus of epithelia and tumor cells in oral lesions. Analysis revealed the specific presence of HPV DNA in all cases of SCC in our Japanese (10/10) and Chinese (10/10) population samples. These results suggest that HPV infection could be one of several risk factors contributing to oral SCC in Japanese and Chinese.

Suprabasal expression of Ki-67 antigen as a marker for the presence and severity of oral epithelial dysplasia

BACKGROUND

Suprabasal expression of Ki-67 is assessed as a marker for oral dysplasia. The study involved non-neoplastic epithelium adjacent to 74 oral squamous cell carcinomas.

METHODS

An immunohistochemical technique was carried out (peroxidase-antiperoxidase) with the monoclonal antibody MIB-1. Epithelial expression of Ki-67 was classified as being absent, basal, and suprabasal. The epithelium was normal in 19 cases, hyperplastic in 38 cases, and dysplastic in 37 cases. The dysplasia was slight in 20 cases, moderate in 12 cases, and severe in 5 cases.

RESULTS

The results of the expression of Ki-67 were in normal epithelium, basal expression 9 cases, absent 10 cases; in hyperplastic epithelium, basal expression 18 cases, absent 20 cases; in dysplastic epithelium, basal and suprabasal expression (always jointly) 27 cases, absent 10 cases; all the severe and moderate dysplasia cases expressed suprabasal Ki-67. A significant association was observed between the presence (p <.0001) and severity (p <.007) of the dysplasia and the suprabasal expression of Ki-67.

Immunohistochemical inactivation of p14ARF concomitant with MDM2 overexpression inversely correlates with p53 overexpression in oral squamous cell carcinoma

The CDKN2 gene encodes two structurally different proteins: a cyclin-dependent kinase inhibitor called p16, which regulates retinoblastoma protein (pRb)-dependent G1 arrest, and a cell cycle inhibitor designated p14ARF, which arrests cell growth in G1-S and also in G2-M. Whereas inactivation of p16 has been described as a frequent event in various cancers, including oral cancer, the current function of p14ARF is still poorly understood. A physical association between p14ARF and MDM2 blocks MDM2-induced p53 degradation, resulting in increased levels of p53, which in turn leads to cell cycle arrest. The present study immunohistochemically examined the expression of p16 and p14ARF together with pRb, MDM2 and p53 status in a series of oral cancers. The results showed that p14ARF was frequently absent in the oral cancers (15/37, 41%) as was p16 immunostaining. Concomitant immunopositivity for p14ARF and MDM2 overexpression was frequently observed in a subset of the cancers, whereas an inverse correlation between p14ARF and MDM2 expression and the diffuse staining of p53 was clearly detected. Moreover, the results showed that in most cases of oral cancer (35/37, 95%) at least one protein was altered, and lymph node metastasis was more frequent in the tumors with alterations in both the p16/pRb and p14ARF/p53 pathway (8/16, 50%) than in the tumors with one or no alteration of these two major pathways.

Differential expression of p16(INK4a) in azoxymethane-induced mouse colon tumorigenesis

Alterations in the p16(INK4a) gene have been implicated in the pathogenesis of different human cancers and animal tumors. We postulated that alterations in the p16(INK4a) gene may also be involved in mouse colon tumorigenesis induced by the chemical carcinogen azoxymethane (AOM). In the present study, p16(INK4a) deletion status and its expression were examined in an AOM-induced mouse colon tumor model. Polymerase chain reaction-based deletion analysis of p16(INK4a) exon 2 showed no deletions in the colon tumors. The expression and localization of p16(INK4a) and its gene product were examined by reverse transcription-polymerase chain reaction and immunohistochemical analyses, respectively. The p16(INK4a) mRNA levels were low, and in some cases undetectable, in control colon tissue. However, colon tumors exhibited an eightfold increase in p16(INK4a) mRNA level when compared with control colon tissue (P < 0.01). Whereas control colon epithelium was uniformly negative for p16(INK4a) immunoreactivity, p16(INK4a)-immunoreactive cells were markedly increased in preneoplastic lesions and adenomas isolated from AOM-treated mice. To further examine the p16(INK4a) regulatory pathway, the retinoblastoma tumor-suppressor protein (Rb) was also examined immunohistochemically in these tissues. A heterogeneous Rb immunostaining was observed in preneoplastic lesions and adenomas. Immunohistochemical analysis also showed a reciprocal relationship between p16(INK4a) and Rb protein expression. These findings suggest that alterations in the p16(INK4a)/Rb pathway may play an important role in AOM-induced mouse colon tumorigenesis. Mol. Carcinog. 28:139-147, 2000.