Simultaneously detected aberrant p53 tumor suppressor protein and HPV-DNA localize mostly in separate keratinocytes in anogenital and common warts

Abstract The E6 oncoprotein of human papillomavirus (HPV) is known to inactivate the control function on cell cycle exerted by p53 tumor suppressor protein in vitro by binding to p53 and thus facilitating the degradation of p53. We have applied a simultaneous in situ demonstration method for detecting p53 protein and HPV-DNA on formalin-fixed tissue sections, and investigated the in vivo interrelationship of p53 protein and HPV-DNA. Immunohistochemical staining for p53 protein with polyclonal and monoclonal antibodies, recognizing both wild-type (wt) and mutated p53 protein, was performed first and in situ DNA hybridization (ISH) for HPV types 6/11 or 16/18 with digoxigenin-labelled probes thereafter. 47% (25/53) of 48 histologically confirmed primary or recurrent condylomata acuminata (CA), 2 Bowenoid papulosis (BP) and 3 common wart (CW) biopsies, positive for HPV 6/11 or HPV 16/18 DNA, showed keratinocytes immunopositive for p53 protein. Of these. 11 lesions with abundant numbers of p53-positive cells were further analyzed with the double method. Signals for abnormal p53 protein and HPV-DNA were detected in separate cell nuclei in all biopsies and, additionally, in the same cell nuclei in 3 biopsies (1 BP, 1 CA, 1 CW). Usually the p53 positivity localized more basally in the epidermis than HPV-DNA, although p53- and HPV-positive keratinocytes were always located closely. The findings were similar for HPV-types 6/11 and 16/18. Our finding of both p53 and HPV-6/11 signals in the same cell nuclei may indicate complexing of p53 and low-risk HPV's without degradation of p53. Our results show abnormal p53 expression in HPV-infected skin lesions, and suggest that p53 protein is susceptible to aberrations even in the cells in the vicinity of productive HPV infection. However, it is not yet fully understood how HPV interferes with p53 protein in these cells.     

Human papillomavirus-associated increase in p16INK4A expression in penile lichen sclerosus and squamous cell carcinoma.

BACKGROUND: Human papillomaviruses (HPVs) are sexually transmitted human carcinogens that may play a role in the oncogenesis of penile cancer. OBJECTIVES: To investigate the role of HPV infection and expression of the tumour suppressor protein p16INK4A in the pathogenesis of penile cancer. METHODS: By means of polymerase chain reaction amplification and reverse hybridization line probe assay to detect HPV infection, and immunohistochemical staining for p16INK4A and Ki67, we analysed 26 penile squamous cell carcinomas (SCCs) and 20 independent penile lichen sclerosus (LS) lesions from 46 patients. RESULTS: HPV DNA was found in 54% of penile SCCs and 33% of penile LS cases in single and multiple infections. High-risk HPV 16 was the predominant HPV type detected. No relationship between Ki67 expression and HPV infection was observed. Strong immunostaining for p16INK4A correlated with HPV 16/18 infection in both penile LS and penile SCC. In our penile SCC series the cancer margins were also associated with penile LS in 13 of 26 lesions, and HPV was detected in seven of the 13 SCC cases associated with LS and in six of the 11 SCC lesions not involving LS. CONCLUSIONS: Our study shows a high prevalence of HPV 16 and p16INK4A expression in penile lesions, consistent with an active role for HPV in interfering with the retinoblastoma pathway. High-risk HPV infection could be involved in the tumorigenic process in 50% of penile cancers, and the use of prophylactic HPV vaccines has the potential to prevent these cancers.     

Immunohistochemical staining of p16 in squamous cell carcinomas of the genital and extragenital area

Background and objectivesPositive immunostaining for the tumor suppressor protein p16 is associated with the presence of mucosal or αsubtypes of human papillomavirus (HPV) in cervical and genital squamous cell carcinoma (SCC). The aim of this study was to determine whether p16 immunostaining is also associated with mucosal HPV in extragenital SCC.Material and methodsParaffin sections of lesions located in the genital region (8 genital warts, 3 intraepidermal SCCs, and 7 invasive SCCs) and extragenital area (29 intraepidermal SCCs corresponding to Bowen disease and 10 invasive SCCs) were stained for p16 by immunohistochemistry. Mucosal HPV was detected by polymerase chain reaction (PCR).ResultsIn the genital area, p16 immunostaining was negative in genital warts and positive in all 3 intraepidermal SCCs and 2 invasive SCCs (29%). Mucosal HPV was detected in 6 genital warts and 2 intraepidermal SCCs (100% after exclusion of 3 lesions that could not be analyzed by PCR) and in the 2 invasive SCCs that were positive for p16. In the extragenital area, 19 intraepidermal SCCs (95%) and 2 invasive SCCs (20%) were immunopositive for p16. Mucosal HPV was detected in 4 intraepidermal SCCs (p16 immunopositive) and 1 invasive SCC (p16 immunonegative). In intraepidermal SCCs, p16 immunostaining facilitated the identification of dermal microinfiltration or invasion of normal skin appendages.ConclusionsAccording to our results, unlike in genital SCCs, p16 immunopositivity is independent of the presence of HPV in extragenital SCCs. Compared with intraepidermal SCCs, the absence of p16 protein in invasive SCCs in the extragenital area would indicate progression of the disease.     

Diversity of human papillomavirus types in periungual squamous cell carcinoma

Background There is accumulating evidence that infections with certain high‐risk α‐human papillomaviruses (HPVs) are involved in the pathogenesis of digital squamous cell carcinomas (SCCs) and their precursor lesions (SCCs in situ). Objectives This study was initiated to search for α‐ and β‐HPV infections in a collective of SCC and SCC in situ located on the hands. Methods HPV typing for 36 high‐risk and low‐risk α‐HPV types and 25 β‐HPV types was performed in SCCs located at different sites of the hands. Additionally, immunohistochemical staining for p16^INK4a and Ki67 was performed in 15 samples. Results In total, 25 SCCs/SCCs in situ (six periungual lesions, eight lesions from the proximal or lateral part of the finger, and 11 lesions from the dorsal part of the hand) were analysed for the presence of α‐ and β‐HPV types. Only one lesion (an SCC in situ positive for HPV11 and HPV31) of the dorsal hand and none of the proximal or lateral part finger lesions were α‐HPV positive. In contrast, all six periungual lesions were α‐HPV positive, and the majority (83%) of them carried HPV types other than HPV16 (HPV26, HPV33, HPV51, HPV56 and HPV73). β‐HPV types were found in only two biopsies. p16^INK4a and Ki67 expression was significantly higher in HPV‐positive lesions as compared with HPV‐negative tumours, and both markers significantly correlated with each other. Conclusions In contrast to other locations of the hands, periungual SCCs are frequently associated with α‐HPV infections. Several high‐risk HPV types other than HPV16 can induce periungual SCCs. Given the high recurrence rate and high proliferative activity of HPV‐associated periungual SCCs, aggressive treatment and close follow‐up of these tumours is mandatory.     

Role of p21(Waf-1) in regulating the G1 and G2/M checkpoints in ultraviolet-irradiated keratinocytes

This study examines the role of p21(Waf-1) , a p53-dependent protein, in regulating mechanisms that protect keratinocytes against ultraviolet-B-induced cellular damage. Keratinocytes from p21(Waf-1) or p53-deficient mice were irradiated with ultraviolet B, and examined for DNA repair, cell cycle progression, and cell death. Both p21(Waf-1) -deficient and p53-deficient cells failed to maintain G2 arrest, and p21(Waf-1) -deficient cells, and to a lesser extent p53-deficient cells, also failed to undergo G1 arrest. After exposure to ultraviolet B, p53-deficient cells were more susceptible to cell death than wild-type cells. p21(Waf-1) -deficient cells did not undergo apoptotic cell death more often, however, but did have an increased frequency of nuclear abnormalities, suggesting mitotic catastrophe. TUNEL assay showed DNA fragmentation in the p53 +/+, p21(Waf-1) +/+, and p53 -/- cells, but not in p21(Waf-1) -/- cells. This result is consistent with the suggestion that p21(Waf-1) -deficient keratinocytes undergo mitotic cell death (catastrophe) after exposure to ultraviolet B irradiation in the system. Western analysis demonstrated that p21(Waf-1) expression was upregulated in p53-proficient and -deficient keratinocytes, supporting the notion that a p53-independent mechanism contributes to the response to ultraviolet B in keratinocytes. Finally, p21(Waf-1) -deficient cells had slightly less efficient nucleotide excision repair. In summary, this study suggests that p21(Waf-1) regulates the ultraviolet-B-induced G2/M checkpoint through p53, and the G1 checkpoint partially through p53. p21(Waf-1) does not significantly regulate DNA repair in ultraviolet-irradiated keratinocytes, however.     

16型人乳头瘤病毒E6/E7诱导角质形成细胞表达热休克蛋白70

目的 了解１６型人乳头瘤病毒（ＨＰＶ１６）Ｅ６／Ｅ７、ＨＳＰ７０与角质形成细胞永生化及转化之间的关系。方法 Ｌｉｐｏｆｅｃｔａｍｉｎｅ介导法进行转染,以Ｇ４１８筛选阳性克隆,免疫印迹分析及免疫荧光双标记染色结合激光扫描共聚焦显微镜对ＨＳＰ７０和ＨＰＶ１６Ｅ６／Ｅ７在转染然质形成细胞中的表达进行了观察。结果 免疫印迹分析显示正常负擀形成细胞和转染角质形成细胞均在相对分子质量７００００处出现一条染色带     

HPV and p53 in cervical cancer.

OBJECTIVE--To determine the prevalence of HPV 16 and 18 E6 by DNA detection and p53 abnormal protein expression in cervical cancers in Hong Kong. MATERIALS AND METHODS--Seventy-three squamous cell cervical cancer biopsy were analysed. Detection of HPV DNA was carried out by the polymerase chain reaction and Southern blotting (PCR/SB) technique using primers to the HPV16 & 18 E6 region and consensus primers to the L1 region. Abnormal expression of the p53 protein was detected by immunohistochemical staining (IHS) using the antibody CM1 on frozen sections of 55 cervical cancer samples. Forty-six samples were analysed for both the presence of HPV DNA and abnormal expression of p53. RESULTS--67.2% of the 64 samples showed the presence of HPV 16 E6 DNA and 39.1% showed the presence of HPV 18 E6 DNA. 32.8% showed the presence of both HPV 16 and 18 E6 DNA. No HPV DNA was shown in 10.9% of samples. Only 3.6% (2) of 55 samples showed positive IHS with CM1. One occurred in a HPV negative sample and the other in a HPV positive sample. CONCLUSION--A high prevalence of HPV DNA was detected in cervical cancer in Hong Kong using the PCR/SB technique. However, abnormal expression of p53 was uncommon amongst patients with or without HPV 16 or 18 infection.     

尖锐湿疣皮损中HPV类型及p53、bcl—2分子表达研究

目的 探讨尖锐湿疣(CA)中HPV（人乳头瘤病毒）感染类型及其p53和bcl－2（B细胞淋巴瘤样因子2）分子在HPV6／11阳性尖锐湿疣发病中的可能作用。方法 用PCR法检测了22例CA皮损中HPV6／11和HPV16／18,用免疫组化方法检测了尖锐湿疣组织中p53和bcl－2分子的表达。结果 （1）所有标本均为HPV6／11阳性,未检测出HPV16／18;（2）40．9％的尖锐疣皮损在表皮角质形成细胞中有p53蛋白的表达,但阳性细胞数量较少,主要散在分布于基底层;（3）bcl－2蛋白在CA及鳞状细胞癌中未见表达。结论 （1）HPV6／11是CA的主要致病病毒;（2）CA中部分出现p53分子表达提示这部分细胞可能已出现恶性转化倾向;（3）bcl-2可能与角质形成细胞来源的良性增生性疾病以及恶性肿瘤关系不大。     

p53 p21和PCNA在寻常疣中的过度表达

目的：研究寻常疣ｐ５３蛋白、ｐ２１蛋白和增殖细胞核抗原（ＰＣＮＡ）过度表达与人类乳头瘤病毒（ＨＰＶ）感染的关系。方法：采用免疫组化方法对石蜡包埋组织标本进行检测。结果：１５例寻常疣皮损中ｐ５３、ｐ２１以及ＰＣＮＡ阳性标本分别为６例（４０％）、５例（３３％）和９例（６６％）。ｐ５３阳性细胞多位于基底层，ｐ２１阳性细胞则多分布于棘细胞层的中下层，ＰＣＮＡ阳性细胞散在分布于整个增生的表皮。受ＨＰＶ感染的空泡样变性细胞核中均有ｐ５３、ｐ２１以及ＰＣＮＡ过度表达者４例。结论：证实了寻常疣中存在ｐ５３、ｐ２１和ＰＣＮＡ过度表达，并从原位上找到ＨＰＶ感染与ｐ５３、ｐ２１过度表达和细胞异常增生相关联的细胞学证据。     

GADD45 regulates G2/M arrest,DNA repair,and cell death in keratinocytes following ultraviolet exposure

GADD45 is a multifunctional protein that is regulated by p53. p53 plays an important role in regulating DNA repair and in the response to ultraviolet light in keratinocytes. This study investigates the role of GADD45 in the response to ultraviolet B. Cell cycle analysis demonstrated that wild-type and Gadd45-deficient cells have transient G2/M arrest, but only in the wild-type cells was arrest sustained. Cdc2 kinase activity in immunoprecipitates from normal and Gadd45-deficient cells decreases after irradiation in normal cells but not in Gadd45-deficient cells. An immunofluorescent study with Cdc2 antibody demonstrated diffuse cellular fluorescence before ultraviolet irradiation in both Gadd45-deficient and wild-type cells, but upon ultraviolet irradiation only Gadd45-proficient cells showed Cdc2 sequestration in the cytoplasm. Gadd45-deficient cells also have a slower rate of nucleotide excision repair. The lack of G2/M arrest coupled with reduced DNA repair leads to a higher ultraviolet sensitivity of Gadd45-deficient cells. These results reveal that GADD45 promotes G2/M arrest via nuclear export and kinase activity of Cdc2, increases global genomic DNA repair, and inhibits cell death in keratinocytes. Thus, GADD45 plays an important role in maintaining genomic integrity in ultraviolet-exposed skin.     

外阴HPV相关疾病中p~(53),cyclinD1和ki67蛋白表达及其与HPV感染的关系

目的 探讨人乳头瘤病毒(HPV)在外阴HPV相关疾病—尖锐湿疣(CA)、外阴上皮内瘤变(VIN)和外阴鳞状细胞癌(VSCC)中的感染情况及与p53,cyclinD1,ki67蛋白表达的关系。方法 在110例外阴HPV相关疾病中应用核酸分子快速导流杂交基因分型技术检测HPV16/18,HPV6/11的表达,同时用免疫组化SP法检测p53,cyclinD1,ki67蛋白的表达,并与10例正常组织进行对照。结果 HPV16/18在CA组,VIN组及VSCC组的阳性表达率均高于正常对照组,而且其阳性表达率随外阴上皮恶性程度增加而增加;HPV6/11在CA组及VINⅠ组的阳性表达率均高于VINⅡ组及VINⅢ组和正常对照组;以上差异均有统计学意义(P均<0.05)。HPV6/11在VSCC组无阳性表达,HPV16/18感染与p53,ki67表达呈正相关,与cyclinD1表达无相关性。HPV6/11感染与p53,cyclinD1,ki67表达无相关性。结论 HPV16/18感染与重度外阴上皮内瘤变及外阴鳞状细胞癌密切相关;HPV6/11感染是尖锐湿疣及轻度外阴上皮内瘤变的重要病因。HPV16/18感染与p53,ki67蛋白表达呈正相关,它们在外阴鳞状上皮恶变过程中有着协同的作用。     

Cyclin D and retinoblastoma gene product expression in actinic keratosis and cutaneous squamous cell carcinoma in relation to p53 expression

Masato Ueda, Abnormality of the molecules regulating the cell cycle has been shown to lead cells to transformation. Recently, overexpression of cyclin D protein, one of the G1 cyclins, and the abnormality of the retinoblastoma gene have been found in various human cancers. We analyzed the expression of cyclin D, retinoblastoma gene product (pRB) and p53 in actinic keratoses (AKs) and cutaneous squamous cell carcinomas (SCCs) by immunohistochemistry to elucidate the role of these molecules in keratinocyte carcinogenesis. In the normal epidermis, a few cyclin D positive cells were seen mainly at die basal layer. In 11 seborrheic keratoses, no overexpression of cyclin D was observed. Twelve of 26 AKs (4.5%) and 27 of 45 SCCs (60%) showed cyclin D overexpression. A few pRB positive cells were seen in the basal layer and in the supra-basal spinous layer of the normal epidermis. An abnormality of pRB, loss of expression, was seen in 2 of 26 AKs (8%) and 7 of 45 SCCs (16%). p53 protein was positive in 12 of 26 AKs (46%) and 24 of 45 SCCs (53%). Forty-five SCCs examined were divided into 22 ultraviolet (UV)-related SCCs and 23 UV-unrelated SCCs. Though UV-related SCCs showed a significantly higher incidence of p53 positivity, as previously reported by us, no significant difference in cyclin D overexpression and loss of the pRB expression was observed between UV-related and UV-unrelated SCCs. These results suggest that cyclin D overexpression is frequently involved in keratinocyte carcinogenesis and that this is an early event, as well as p53 abnormality. In addition, abnormality of the retinoblastoma gene is also related to epidermal cell carcinogenesis, though die frequency is relatively low.     

Cutaneous manifestations of dabrafenib (GSK2118436): a selective inhibitor of mutant BRAF in patients with metastatic melanoma

Background Inhibitors of mutant BRAF are emerging as standard of care in patients with metastatic melanoma carrying relevant oncogenic mutations. Cutaneous reactions are frequent and significant. We conducted a systematic prospective dermatological review of all patients enrolled at a single institution in the phase I/II clinical trial of the mutant BRAF inhibitor dabrafenib (GSK2118436). Objectives To identify the cutaneous manifestations of the BRAF inhibitor dabrafenib; to form diagnostic criteria to standardize the diagnosis of verrucal keratotic squamoproliferative lesions; and to bring awareness to the medical community of the importance of dermatological assessment of patients taking dabrafenib. Methods Patients enrolled in the phase I/II trial (n = 43) were monitored for the development of new skin lesions. Each new lesion was photographed, a clinical diagnosis recorded and, where appropriate, a biopsy taken. Human papillomavirus (HPV) and p16 immunohistochemistry analyses were performed. Results The most frequently observed lesions were verrucal keratotic squamoproliferative lesions (49%), Grover’s disease (27%) and reactive hyperkeratotic lesions on the soles, at points of friction (22%). Eighteen squamous cell carcinomas (SCCs) occurred in 20% of patients. Most SCCs appeared between weeks 6 and 24 following commencement of therapy on both sun‐damaged and nonsun‐damaged skin. All SCCs were well differentiated, five were of the keratoacanthoma type, and two were SCC in situ. Other lesions observed included seborrhoeic keratoses, epidermal cysts, acneiform eruptions, hair loss and changes in hair structure. HPV was negative in 15 of the 16 tissues studied and p16 expression was higher in SCCs compared with verrucal keratoses. Conclusions Administration of the mutant BRAF inhibitor dabrafenib is associated with induction of keratinocytic proliferation, which in some cases develops features of low‐grade malignancy. Highly oncogenic HPV infection is unlikely to be a contributor to the formation of SCCs or verrucal keratoses.     

培养角质形成细胞构成性表达热休克蛋白72

目的 了解热休克蛋白７２（ＨＳＰ７２）在培养角质形成细胞中的表达情况。方法 无血清培养基培养原代角质形成细胞,免疫组织化学（ＳＡＢＣ）及核酸原位杂交技术检测ＨＳＰ７２的表达。结果 角质形成细胞的细胞中常见阳性染色,少数大细胞中ＨＳＰ７２表达增强,集中在细胞核周围。结论：普通条件培养的皮肤角质形成细胞即可构成性表达ＨＳＰ７２,可能对维持角质形成细胞的正常功能和活性方面个有重要作用。     

Differential p53-mediated responses to solar-simulated radiation in human papillomavirus type 16-infected keratinocytes

In immunocompromised patients, cooperative effects of human papillomavirus (HPV) and ultraviolet (UV) radiation have been postulated in the development of non-melanoma skin cancers. The tumor suppressor p53 is a key component of the cellular response to genotoxic agents, such as UV radiation. We have previously demonstrated that in HPV16-infected cells, a higher E6* level was associated with a higher resistance to UV and oxidative stress. Using the two same SKv cell lines, the aim of the present study was to investigate p53 and p21 expression and cell death in HPV-infected keratinocytes in response to UV irradiation and to determine the role of HPV oncoprotein levels on the p53-mediated cellular response. We demonstrated that the weakly E6*-expressing level SKv-e cell line presented both higher cytotoxicity and apoptosis to UV. This high sensitivity was associated with both p53 and p21 nuclear accumulation, while a high E6* level and resistance were associated with no p53 accumulation and a p21 nuclear down-regulation after UV. Moreover, in SKv-e cell line, p21 promoter activation was p53 dependent. Our results suggest that an alteration and/or a modulation of the p53-p21 pathway in response to UV could be determinant for HPV-infected keratinocyte survival and HPV-associated carcinogenic process.     

Abnormal expression and mutation of p53 in cervical cancer--a study at protein, RNA and DNA levels.

OBJECTIVES: The objectives of this study are to document the status of p53 expression and mutation in cervical cancer at protein, RNA and DNA levels and to relate this to the presence of HPV. MATERIALS AND METHODS: Biopsy specimens from one hundred and three squamous cell carcinoma of the cervix and histologically normal ectocervix were analysed. Fresh tissues were extracted for protein, RNA and DNA and flash frozen tissue cryostat sectioned for immunohistochemical staining. HPV DNA status was determined by PCR using L1 consensus primers and typed for HPV 16 and 18 with E6 specific primers. p53 expression was determined at the protein level by Western blotting on protein extracts and at RNA level by Northern blotting. RESULTS: There was no p53 overexpression or mutation detectable in the protein extracts. Three of 65 (4.6%) of the carcinomas were positive for p53 by immunostaining with the polyclonal antibody CM1. Overexpression at the RNA level was detected in 2 of 32 (6.3%) carcinomas. p53 mutation was screened for by PCR/SSCP (single strand conformation polymorphism) followed by sequencing to define the site of mutation. Two of the cervical cancers (2.0%) showed mutation in p53 in exons 7 or 8. The mutation rate in HPV positive tumours was 1.2% (1/81) and in HPV negative tumours was 5.2% (1/19). CONCLUSION: p53 overexpression or mutation does not seem to play a significant role in cervical carcinomas.     

Immunophenotypic analysis of the p53 gene in non-melanoma skin cancer and correlation with apoptosis and cell proliferation

BACKGROUND: Sunlight precipitates a series of genetic events that lead to the development of skin cancers such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The p53 tumour suppressor gene, which plays a pivotal role in cell division and apoptosis, is frequently found mutated in sunlight-induced skin tumours. OBJECTIVE: To investigate the immunoreactivity of the p53 gene in non-melanoma skin cancers and to correlate its expression with apoptotic and cell proliferation markers. METHODS: We analysed 35 non-melanoma tumours including 19 BCCs and 16 SCCs from sun-exposed skin areas. p53 protein expression was studied immunohistochemically using the DO7 monoclonal antibody against wild-type and mutant p53 forms. The percentage of p53-immunopositive nuclei was measured by image analysis. Cell proliferation and apoptosis were also assessed by image analysis following Ki-67 immunostaining and application of the TUNEL method on paraffin sections, respectively. RESULTS: The percentage of p53-expressing cells varied from 3.5 to 90 in BCCs (median value 54.4%) and from 3.7 to 94 in SCCs (median value 40.3%). The mean value of Ki-67-positive cells was comparable in both groups of tumours with a mean value of 40.6% in BCCs and 34.6% in SCCs. Conversely, the TUNEL assay showed sporadic staining of apoptotic cells within the tumours with a mean value of 1.12% in BCCs and 1.8% in SCCs. p53 protein expression was correlated positively with cell proliferation (r = 0.75, P = 0.000001) and negatively with apoptosis (r = -0.23, P = 0.05). CONCLUSION: p53 immunoreactivity was high in the majority of the skin carcinomas examined and correlated positively with cell proliferation and negatively with apoptosis. The p53 protein overexpression appears to be related to an inactivated protein resulting from mutations of the p53 gene or other unclear molecular mechanisms.     

Epigenetic abnormalities in cutaneous squamous cell carcinomas: frequent inactivation of the RB1/p16 and p53 pathways

BACKGROUND: Aberrant methylation of CpG islands in the promoter regions of cancer-related genes has been demonstrated in many human tumours. However, the methylation profile of these regions in cutaneous squamous cell carcinomas (SCCs) has not been well studied. OBJECTIVES: To examine epigenetic abnormalities of a wide range of cancer-related genes in SCCs. METHODS: We investigated the methylation status of 11 candidate cancer-related genes (CDH1, p16(INK4a), p14(ARF), DAPK1, MGMT, RB1, RASSF1, p15(INK4b), PTEN, PRDM2 and p53) in 20 cases of SCC by methylation-specific polymerase chain reaction, and comparatively examined the protein production of E-cadherin (CDH1), p16, RB1, p14, BMI1 and cyclin A by immunohistochemical analysis. RESULTS: The frequency of cancer-related gene methylation in SCCs was: CDH1 (95%), p16 (20%), p14 (15%), DAPK1 (15%), MGMT (15%), RB1 (5%), RASSF1 (5%), p15 (0%), PTEN (0%), PRDM2 (0%) and p53 (0%). Almost all cases with hypermethylation of CDH1, p16, RB1 and p14 showed no obvious production of each protein, suggesting that promoter hypermethylation of these genes contributes to the loss of protein production. The results of methylation analysis, in combination with the results of our previous mutation analysis of CDKN2A locus and p53, revealed that 70% of SCCs have alterations in the RB1/p16 or p53 pathway. CONCLUSIONS: Our findings indicate that the promoter hypermethylation of cancer-related genes, especially CDH1, is frequently shown in SCCs, and dysregulation of the RB1/p16 and/or p53 pathway through either genetic or epigenetic mechanisms, except for epigenetic abnormalities of p53 itself, should contribute to the carcinogenesis of SCCs.