p16 overexpression identifies HPV-positive vulvar squamous cell carcinomas

Two types of vulvar squamous cell carcinomas (VSCCs) are recognized according to their relationship to human papillomavirus (HPV). Basaloid or warty carcinomas are considered HPV-associated tumors, whereas differentiated keratinizing neoplasms are considered non-HPV-associated. Recently, immunohistochemical detection of p16 and p53 has been proposed to differentiate these 2 types of VSCCs. We conducted a histologic study with immunohistochemical evaluation of p16 and p53 and HPV detection and typing by polymerase chain reaction using 2 different sets of primers in 92 cases of VSCCs to evaluate the usefulness of immunohistochemistry in the classification of VSCCs and to describe the clinico-pathologic characteristics of both types of VSCCs. HPV was detected in 16/92 (17.4%) specimens, HPV16 being identified in 75% of positive cases. A significant number of discrepancies between histology and HPV detection were observed, with 37.5% of HPV-positive tumors being keratinizing and 9.2% of HPV-negative carcinomas showing basaloid or warty features. Diffuse positivity for p16 and p53 was observed in 100% and 6.2% of HPV-positive tumors and in 2.3% and 64.5% of HPV-negative neoplasms, respectively. The sensitivity and specificity of p16 immunostaining to detect HPV-associated carcinomas (100% and 98.7%, respectively) were better than those of histologic criteria (93.8% and 35.5%) and of p53 negative stain (62.5% and 93.4%). Vulvar intraepithelial neoplasia grade 3 of basaloid/warty type was identified in 53.8% HPV-positive tumors, including 3 keratinizing tumors. All these cases were p16 positive and p53 negative. Vulvar intraepithelial neoplasia grade 3 of differentiated type was observed in 45.6% of HPV-negative cases; 90.8% of them were positive for p53 but all were negative for p16. No differences in age, stage, or development of recurrence were observed between HPV-positive and negative tumors. In summary, the current morphologic criteria to discriminate HPV-positive and negative VSCCs have a significant overlap. Immunostaining for p16 is a reliable marker for HPV-positive VSSCs, which improves the results of histologic classification.     

Human papillomavirus and p53 mutational status as prognostic factors in head and neck carcinoma

BACKGROUND: Mutations of the p53 tumor-suppressor gene are common in squamous cell carcinoma of the head and neck (SCCHN) and may portend a worse prognosis. Human papillomavirus (HPV) represents another potential prognostic factor for SCCHN. The oncogenic potential of HPV may be due to the ability of its E6 oncoprotein to promote degradation of wild-type p53 protein. We wish to determine whether there is a lower incidence of p53 mutations in HPV-positive versus HPV-negative tumors, and if HPV and/or p53 status has an impact on survival. METHODS: Thirty-two SCCHN specimens were analyzed for mutations of the p53 gene using single-strand conformational polymorphism (SSCP) analysis followed by DNA sequencing. The HPV status of all specimens was evaluated by use of polymerase chain reaction with HPV consensus primers and Southern blot hybridization. Pertinent clinical information was obtained from chart review. RESULTS: Nonsilent p53 mutations were present in 2 of 15 (13%) of HPV-positive tumors compared with 6 of 17 (35%) of HPV-negative tumors (p =.229; Fisher's exact test, odds ratio.28). A survival advantage was found between HPV-positive compared with HPV-negative specimens (p =.0264) and between p53 wild type compared with p53 mutant specimens (p =.01) by univariate log rank analysis. When stratified according to both HPV and p53 status, a statistically significant survival difference was observed largely because of a 100% survival for the HPV-positive/p53 wild-type group (p =.003). CONCLUSIONS: This preliminary study supports the notion that the presence of HPV confers a survival advantage among HNSCC patients, particularly when p53 is wild type.     

Prevalence of human papillomavirus type 16 DNA in squamous cell carcinoma of the palatine tonsil, and not the oral cavity, in young patients: a distinct clinicopathologic and molecular disease entity

Squamous cell carcinoma of the head and neck commonly affects patients in their sixth decade and older, particularly those with a prolonged history of alcohol and tobacco abuse. Less frequently, carcinomas occur in young individuals even in the absence of known risk factors. The purpose of this study is to investigate a possible relationship between these tumors and human papilloma virus (HPV). Thirty-three cases of squamous cell carcinoma of the head and neck in young patients under the age of 40 years were studied: 15 oral, 11 tonsillar, and 7 laryngeal. HPV DNA was detected by polymerase chain reaction in 10 tonsillar and 2 laryngeal carcinomas and in none of the oral tumors. Of the 12 HPV-positive tumors, 11 were HPV16 and 1 was HPV31. HPV-positive tumors had a distinct nonkeratinizing basal cell morphology, they stained diffusely and strongly with p16 antibodies, had higher Ki-67 and lower p53 staining scores as compared with the conventional keratinizing HPV negative carcinomas. It is concluded that in young patients high-risk HPV, particularly HPV16, is strongly associated with tonsillar squamous cell carcinoma and some cases of laryngeal, but not oral, tumors. The HPV-positive carcinomas have a distinct histopathologic and immunophenotypic features.     

Use of combined molecular biomarkers for prediction of clinical outcomes in locally advanced tonsillar cancers treated with chemoradiotherapy alone

Background.

Environmental exposures to tobacco, alcohol, human papillomavirus (HPV) and/or Epstein‐Barr virus (EBV), all of which can perturb multiple cell cycle proteins or tumor suppressors, have been implicated in the pathogenesis of different subsets of head and neck cancers. The aim of this study was to investigate to which extent the virus infection by itself, and/or the altered cell cycle proteins, contributes to prognosis in locally advanced tonsillar squamous cell carcinomas (TSCCs) treated with concurrent chemoradiotherapy (CCRT) alone.

Methods.

Serial tumor tissue arrays from archival samples were tested for the presence of HPV genome integration or EBV episome by means of DNA sequencing, real‐time polymerase chain reaction (PCR), and in situ hybridization. Alterations of cell cycle proteins (p53, pRb, and p21) were evaluated by immunohistochemical staining. The association of viral presence with altered cell cycle proteins was correlated to clinical outcomes.

Results.

Of the 46 patients with the same T2N2bM0 stage IVA among consecutive patients with TSCC, 23 (50%) had integrated HPV DNA and only 1 (2%) had EBV episome. The HPV types detected were almost all HPV‐16. A reduced expression pattern of p53, pRb, and p21 was noted in HPV‐positive tumors, and the incremental number of alterations in the 3 proteins was significantly associated with HPV‐negative tumors. The presence or absence of HPV together with the number of altered expression of the 3 cell cycle markers resulted in further identification of 4 biologically and clinically distinct subgroups with different outcomes after CCRT.

Conclusions.

Use of combined biomarkers of oncogenic HPV and tumor suppressors of p53, pRb, and p21 in advanced TSCC provides prognostic molecular classification superior to the TNM stage system and identifies low‐risk patients for organ preservation by CCRT alone and high‐risk patients who might benefit from planned tonsillectomy and neck dissection before or after CCRT. © 2008 Wiley Periodicals, Inc. Head Neck, 2009     

p21, p53, and p27 Kip1 alterations in benign and malignant tumors of sinonasal epithelium.

OBJECTIVE: The goal of this study was to investigate alterations of cell cycle-related molecules, including p27, p21, and p53, in inverted papillomas (IPs) and squamous cell carcinomas (SCCs) of the sinonasal epithelium.Study design Sixteen IPs and 6 SCCs of the sinonasal epithelium, surgically resected at Istanbul Faculty of Medicine, Department of Otorhinolaryngology, from 1992 to 2000 were immunohistochemically investigated (p27, p21, and p53). RESULTS: A significant decrease in p27 nuclear staining was observed for SCCs of paranasal sinus compared with inverted papillomas (P = 0.0072). In SCCs there was no association between p27 expression and the presence of keratinization and tumor grade. p21 and p53 expressions were not associated with IPs (dysplastic and nondysplastic) and SCCs. CONCLUSION: Reduced levels of p27 expression correlate with increased cell proliferation in tumors of sinonasal region. Our findings indicate that p27 immunohistochemistry can be recommended to analyze the dysregulation of cell kinetics in these tumors.     

Human papillomavirus infection in "young" versus "old" patients with squamous cell carcinoma of the head and neck

BACKGROUND: Human papillomavirus (HPV) represents a potential risk factor for squamous cell cancer of the head and neck (SCCHN). We evaluated the prevalence of HPV DNA in patients with SCCHN diagnosed at the University of Michigan from 1994-1996. METHODS: Patients were stratified by age at diagnosis as "young" (<50 years; median, 39) or "old" (>50 years; median, 66). Fourteen "young" and 14 "old" were matched for tumor site, and 4 additional "old" patients were included. Specimens were analyzed by polymerase chain reaction for HPV DNA using 2 sets of consensus primers. HPV sequences were confirmed by Southern blot hybridization and typed with type-specific probes. RESULTS: Overall, 15 of 32 (46.9%) samples contained HPV sequences. HPV 16 was detected in 9 of 15 (60%), HPV-18 in 1 of 15 (6.6%), and 5 of 15 (33.3%) remained untyped by multiple methods. When stratified, 7 of 14 (50%) "young" were HPV-positive compared with 8 of 18 (44.4%) "old" (p =.76). Survival in patients with HPV-positive SCCHN was significantly longer than that for HPV-negative patients. CONCLUSIONS: The incidence of HPV in "young" versus "old" is not significantly different, suggesting similar roles for both groups. Patients with HPV-positive tumors may have a survival advantage relative to patients with HPV-negative tumors.     

Expression of p16(INK4A), p53, and Rb proteins are independent from the presence of human papillomavirus genes in oral squamous cell carcinoma.

BACKGROUND: The overexpression of p16(INK4A) and suppression of p53 and Rb proteins are key features of oncogenic transformation by human papillomaviruses (HPV) in anogenital cancers. HPV genomes are often detected in cancers of the oral cavity, but it is unclear whether HPV has a specific oncogenic role there. OBJECTIVES: The objectives of the study were to investigate the expression of p53, Rb, and p16(INK4A) proteins and identify HPV infection and viral integration into the host genome. METHODS: Seventy-nine cases of oral squamous cell carcinoma (OSCC) were studied by immunohistochemistry. Polymerase chain reaction (PCR) was performed to identify HPV DNA from the samples. The results were correlated with clinical data. RESULTS: Thirty-three cases were HPV positive for high-risk HPV (HR-HPV) types, of which 27 harbored HPV16. In 25 of 27 HPV16-positive tumors, the HPV16 genome was fully integrated into the host genome, as evidenced by the lack of PCR-amplifiable E2 gene sequences. Forty-five patients were p53 overexpressing, 20 with HR-HPV-positive and 25 with HR-HPV-negative tumors. p16(INK4A) protein was overexpressed in 4 of 31 HR-HPV-positive and 9of 45 HR-HPV-negative cases. Twenty-six of 32 HR-HPV-positive and 37 of 44 HR-HPV-negative samples exhibited pRb nuclear staining. These differences between HR-HPV-positive and -negative tumors were not statistically significant. No correlation was found between these biological factors and tumor location, stage, differentiation grade, or alcohol or tobacco abuse. CONCLUSIONS: A tumor immunophenotype, similar to HPV-related anogenital cancers, is not present in OSCC and highly oncogenic HPV types are therefore unlikely to be specific or independent risk factors for oral cancer.     

Epidemiology and clinical aspects of HPV in head and neck cancers

Human papillomavirus (HPV) infection is now established as a major etiologic factor for oropharyngeal cancers. Case-control studies conducted around the world show strong and consistent associations of markers of HPV exposure with risk of oropharyngeal cancers (range of odds ratios [OR] for oral oncogenic HPV infections = 3.6-230.0, ORs for HPV16 L1 antibodies = 2.3-182.0, and ORs for HPV16 E6/E7 antibodies = 9.2-231.0. HPV-positive oropharyngeal cancers are epidemiologically distinct from HPV-negative ones, and are characterized by younger age at onset, male predominance, and strong association with sexual behaviors. Importantly, HPV-positive oropharyngeal cancer patients have substantially improved outcomes (28-80 % reductions in the risk of death) than HPV-negative patients. Given the superior survival, younger age, and good performance status of HPV-positive oropharyngeal cancer patients, de-intensified therapies are currently being considered for this group of patients. Recent analyses of cancer registry data show dramatic increases in incidence of oropharyngeal cancers during the past 15-20 years in several parts of the world, highlighting the need for prevention strategies. If proven efficacious, currently available prophylactic HPV vaccines hold great promise for primary prevention of HPV-associated oropharyngeal cancers.     

Epidemiology and Clinical Aspects of HPV in Head and Neck Cancers

Human papillomavirus (HPV) infection is now established as a major etiologic factor for oropharyngeal cancers. Case–control studies conducted around the world show strong and consistent associations of markers of HPV exposure with risk of oropharyngeal cancers (range of odds ratios [OR] for oral oncogenic HPV infections = 3.6–230.0, ORs for HPV16 L1 antibodies = 2.3–182.0, and ORs for HPV16 E6/E7 antibodies = 9.2–231.0. HPV-positive oropharyngeal cancers are epidemiologically distinct from HPV-negative ones, and are characterized by younger age at onset, male predominance, and strong association with sexual behaviors. Importantly, HPV-positive oropharyngeal cancer patients have substantially improved outcomes (28–80 % reductions in the risk of death) than HPV-negative patients. Given the superior survival, younger age, and good performance status of HPV-positive oropharyngeal cancer patients, de-intensified therapies are currently being considered for this group of patients. Recent analyses of cancer registry data show dramatic increases in incidence of oropharyngeal cancers during the past 15–20 years in several parts of the world, highlighting the need for prevention strategies. If proven efficacious, currently available prophylactic HPV vaccines hold great promise for primary prevention of HPV-associated oropharyngeal cancers.     

Detection of human papillomavirus DNA and expression of p16, Rb, and p53 proteins in small cell carcinomas of the uterine cervix

Human papillomavirus (HPV) has been implicated as an etiologic agent for the development of primary small cell carcinoma of the uterine cervix, a rare but highly aggressive malignancy. It has been shown that the HPV E6 and E7 oncoproteins are able to inactivate the tumor suppressor functions of p53 and Rb. In squamous cell carcinoma and adenocarcinoma of the cervix, HPV infection is also associated with overexpression of p16, a cyclin-dependent kinase inhibitor. In this study, 22 cases of primary small cell carcinoma of the uterine cervix were subjected to broad-spectrum HPV DNA amplification and typing, and immunohistochemically examined for the expression of p16, Rb, and p53 proteins. The results show that HPV DNA was detected in every case (100%), with 18 cases (82%) harboring type 18. The tumor cells exhibited strong nuclear staining for p16 in 20 cases (91%). This was associated with a complete loss of Rb nuclear staining in tumor cells in 16 cases (73%). The p53 protein was essentially undetectable in all cases. In contrast, HPV DNA was not detected in 9 colorectal and 8 urinary bladder small cell carcinomas included in this study for comparison. While similar p16 and Rb expression patterns were observed in these HPV-negative tumors, a different expression pattern for p53 was noted where strong nuclear staining was seen in 8 cases (47%; P = 0.0004 compared with cervical tumors). These observations indicate that different mechanisms are involved in the pathogenesis of small cell carcinomas of the uterine cervix and support the notion that nuclear p16 overexpression serves as an indication of Rb defunctioning in tumor cells, which may or may not result from high-risk HPV infection.     

The cell cycle inhibitory protein p21cip is not essential for maintaining beta-cell cycle arrest or beta-cell function in vivo

p21(cip1), a regulatory molecule upstream of the G(1/0) checkpoint, is increased in beta-cells in response to mitogenic stimulation. Whereas p21(cip1) can variably stimulate or inhibit cell cycle progression, in vitro studies suggest that p21(cip1) acts as an inhibitor in the pancreatic beta-cell. To determine the functional role of p21(cip1) in vivo, we studied p21-null mice. Surprisingly, islet mass, beta-cell replication rates, and function were normal in p21-null mice. We next attempted to drive beta-cell replication in p21-null mice by crossing them with rat insulin II promoter-murine PL-1 (islet-targeted placental lactogen transgenic) mice. Even with this added replicative stimulus of PL, p21-null islets showed no additional stimulation. A G(1/S) proteome scan demonstrated that p21(cip1) loss was not associated with compensatory increases in other cell cycle inhibitors (pRb, p107, p130, p16, p19, and p27), although mild increases in p57 were apparent. Surprisingly, p18, which had been anticipated to increase, was markedly decreased. In summary, isolated p21(cip1) loss, as for pRb, p53, p18, and p27 and other inhibitors, results in normal beta-cell development and function, either because it is not essential or because its function is subserved or complimented by another protein. These studies underscore marked inhibitory pressure and the complexity and plasticity of inhibitory pathways that restrain beta-cell replication.     

Prevalence of high-risk human papillomavirus DNA in nonkeratinizing (cylindrical cell) carcinoma of the sinonasal tract: a distinct clinicopathologic and molecular disease entity

Carcinomas of the nose and paranasal sinuses are a heterogeneous group of neoplasms that differ histologically, biologically, and clinically. Some of these tumors are known to harbor high-risk human papillomavirus (HPV) DNA. In an attempt to identify specific phenotypes associated with HPV infection, 39 cases of sinonasal carcinomas were evaluated by PCR for the presence of HPV DNA. The tumors were also studied with a panel of immunohistochemical stains, including p16, p53, and Ki-67 antibodies. Twenty-one cases were identified as keratinizing squamous cell carcinoma (KSCC) with a male-to-female ratio of 3:1. Eight cases were nonkeratinizing (cylindrical cell) carcinoma (NKCa) with a male-to-female ratio of 1:1. Ten cases were sinonasal undifferentiated carcinoma (SNUC), and 9 of these patients were men. HPV DNA, particularly type 16, was detected in 9 cases: 4 of 21 (19%) of KSCC, 4 of 8 (50%) of NKCa, and 1 of 10 (10%) of SNUC. In addition to a higher prevalence of HPV DNA in NKCa, the tumors also showed a distinct immunophenotype characterized by strong and diffuse staining for p16, high labeling scores for Ki-67, and negative or low reactivity to p53. On the other hand, KSCC and SNUC were either negative or weakly reactive to p16 antibodies. KSCC cases were more likely to be positive and more strongly reactive to p53 stain. Unlike KSCC, SNUC had high Ki-67 labeling scores. These observations suggest that NKCa of the sinonasal tract is a distinct histopathologic and molecular disease entity, which should be added to the list of upper aerodigestive tract tumors with strong etiologic relationship to high risk HPV.     

Comparative study of the expression of proteins involved in the cell cycle in renal secondary hyperparathyroidism

BACKGROUND: In renal hyperparathyroidism, parathyroid cell proliferation seems to play a key role in the progression of the disease. Therefore, G1/S transition, a main cell cycle regulatory step, could be deregulated in these patients. METHODS: One hundred and one parathyroid glands, taken from parathyroidectomies performed on 41 patients on hemodialysis (HD), and 15 glands, taken from 7 patients with post-transplantation persistent hyperparathyroidism (HPT), were studied. Twelve normal parathyroid (PT) glands were used as the control. Biochemical data, immunohistochemical (IHC) profiles of G1/S transition regulators belonging to the two main pathways (cyclin D1/p16INK4A/pRb and p14ARF/p53/MDM2), and proliferation rate (Ki67) were correlated. RESULTS: All of the other proteins differed from normal IHC profiles in both groups that showed significant higher proliferating rates, decreases in p27KIP1, pRb, and cyclin D1, as well as increases in p16INK4A, p53, MDM2, and p21WAF1 levels, in comparison with normal PT glands, with the exception of cyclin D3. Contrary to patients with HPT who were on hemodialysis, in post-transplantation HPT, consistent correlations between biochemical data and IHC profiles were obtained. CONCLUSION: In both groups IHC profiles of proteins involved in G1/S transition regulation significantly differed from normal PT glands. The results support partial reversion to normal IHC profile in post-transplantation HPT.     

Expression of p53 protein related to human papillomavirus and DNA ploidy in superficial esophageal carcinoma

We examined the p53 protein and human papilloma virus (HPV) by immunohistochemistry and DNA ploidy by cytofluorometry in paraffin-embedded esophageal carcinoma tissue specimens. Sixty-one patients with superficial esophageal carcinoma were operated on between 1983 and 1991 without any prior treatment. Immunostaining of the anti-p53 protein antibody (CM1) was positive in 32 carcinomas (52%). Patients with p53-positive tumors had a poorer outcome than those with p53-negative tumors (P<0.05). In addition, patients with p53-positive tumors did not have any characteristic site of relapse. Only 5 of the 61 patients (8.2%) had HPV-positive tumors. One of these 5 carcinomas expressed both p53 protein and HPV. Three patients with HPV-positive tumors which had invaded the submucosal layer died of relapse. A determination of DNA ploidy revealed 30 patients with aneuploid tumors, 13 with polyploid tumors and 18 with diploid tumors. The outcome of the patients with aneuploid tumors was worse than that of the patients with diploid tumor (P<0.05). p53 protein expression was not associated with DNA ploidy; however, the 16 patients who had both p53-positive and aneuploid tumors had a worse prognosis than patients with p53-negative and aneuploid tumors (P<0.01). These findings suggest that p53 protein expression in conjunction with DNA ploidy may be a useful indicator in evaluating the prognosis of patients with superficial esophageal carcinoma.     

人乳头瘤病毒16阳性与人乳头瘤病毒阴性食管癌的基因表达谱研究

目的 探讨人乳头瘤病毒（HPV）感染在食管癌的发生发展中可能存在的分子机制。方法采用PCR的方法检测食管癌患者中HPv的感染状况及型别．筛选出8例HPV16阳性和7例HPV阴性的食管癌组织样本．进行solexa测序及生物信息分析。结果HPV16阳性患者中共筛选出796个差异基因,其中366个基因上调。430个基因下调。对差异基因进行功能分类和通路分析,发现这些差异基因主要涉及肿瘤发生、免疫和炎性反应、细胞生长增殖以及细胞运动等方面,其中以免疫炎性反应的因子最具代表性。结论免疫因子的差异可能与食管癌中的HPV感染及作用存在一定关联。     

Basaloid in contrast to nonbasaloid head and neck squamous cell carcinomas display aberrations especially in cell cycle control genes

BACKGROUND: At present, the differences between head and neck basaloid squamous cell carcinoma (BSCC) and nonbasaloid squamous cell carcinoma (SCC) are mostly on the basis of histologic and immunohistologic findings. METHODS: In this study, we investigated 8 BSCCs and 59 SCCs for loss of heterozygosity (LOH) at chromosomes 5q, 9p, 9q, 10q, 11q, 13p, 17p, and 18q. In addition, we analyzed p16, PTEN, and CCND1 (cyclin D1) and investigated the HPV status. Immunohistochemically, the expression of MIB-1, p16, p53, and cyclin D1 was determined. RESULTS: Aberrations in the BSCCs were especially frequent at 9p and in the CCND1 gene. In contrast, alterations at 10q occurred almost exclusively in conventional SCCs. Obvious differences could be determined concerning the HPV status: HPV-DNA was detected in all BSCCs but only in 17% of conventional SCCs. CONCLUSIONS: Although the number of investigated BSCCs is rather low and did not allow statistical conclusions, our results focus on certain differences between the molecular pathogenesis of BSCCs and SCCs.     

Combined p53 and retinoblastoma protein detection identifies persistent and regressive cervical high-grade squamous intraepithelial lesions

Most cervical high-grade squamous intraepithelial lesions (HSILs) persist, but approximately one third regress (ie, no HSIL in follow-up biopsies). To identify factors related to histologic proven persistence or regression. Twenty-eight small histologic (marker) biopsies with adequate follow-up were analyzed for human papillomavirus (HPV) genotypes and different immunoquantitative proliferation, cell cycle regulation, and differentiation markers. All cases had a biopsy-interval between the marker and first follow-up biopsy of at least 100 days (median, 8.2 months; range, 3.4-22.5 months). Follow-up was classified as regression or persistence. All lesions were high-risk (hr) HPV and p16 positive, 63% for HPV-16 or HPV-16 mixed with other hr genotypes, while 37% had other hrHPV types. The marker biopsies of the persistent HSILs had lower p53 and retinoblastoma protein (pRb) detected in the deep half of the epithelium (P = 0.001 and 0.02, respectively) than nonpersistent HSILs. The degree of positivity of p16, Ki-67, cyclin D1, lesion extent, positivity of the resection margins, and patient age were all unrelated to persistence or regression. Lesions with HPV-16 or mixed-16 genotypes had a significantly lower percentage of pRb (P = 0.02), p53 (P = 0.02), and cyclin D (P = 0.04) positive nuclei in the deep epithelial layers. In agreement with this, type-16 positive HSILs had a lower regression percentage than those with other HPV types, but the difference was not significant. HSILs with combined negativity/low positivity for p53 and pRb protein in small histologic biopsies are highly likely to persist, contrasting those in which one of these cell cycle regulators is strongly positive (p53 > 15%; pRb > 40%).     

Deletion of the PDZ motif of HPV16 E6 preventing immortalization and anchorage-independent growth in human tonsil epithelial cells

BACKGROUND: Human papillomavirus 16 (HPV16) has been associated with head and neck squamous cell carcinoma (HNSCC) in up to 60% of sampled specimens. METHODS: To understand better the viral genes required to transform human tonsil epithelial cells (HTEC), we isolated HTEC's and transduced them with retroviral vectors containing HPV16 E6 and E7. RESULTS: Immortalization and anchorage-independent growth of HTEC's only occurred with expression of E6 and E7 with resultant degradation of p53. However, cells expressing E6 lacking the PSD-95/disc-large/Zo-1 (PDZ) motif did not immortalize or grow anchorage independent. Telomerase activity and degradation of p53 were similar for wild-type and mutant E6. CONCLUSION: The mechanism of oncogenic transformation by E6 in HTEC's is dependent on the PDZ binding motif. Identification of pathways affected by the interaction of E6 and PDZ domain containing proteins will further our understanding of how HPV causes HNSCC and will provide potential therapeutic targets.     

Expression patterns of cyclins D1, E and cyclin-dependent kinase inhibitors p21(Waf1/Cip1) and p27(Kip1) in urothelial carcinoma: correlation with other cell-cycle-related proteins (Rb, p53, Ki-67 and PCNA) and clinicopathological features

INTRODUCTION: The expression pattern of cyclins D1 and E, as well as cyclin-dependent kinase inhibitors p21(Wa1/Cip1) and p27(Kip1) and their relationship to tumour behaviour and patients' prognosis was examined in 142 urothelial cell carcinomas. The expression of these proteins was also analyzed along with other cell-cycle-related proteins such as: p53, pRb and the proliferation-associated indices Ki-67 and proliferating cell nuclear antigen (PCNA). PATIENTS AND METHODS: These molecule markers were localized immunochemically using the monoclonal antibodies anti-cyclin D1 (DCS-6), anti-cyclin E (13A3), anti-p21 (4D10), and anti-p27 (1B4) in 142 patients with urothelial cell carcinoma. RESULTS: Focal positivity (<10% of tumour cells) or the absence of cyclin D1 immunostaining was observed in 105/142 (73.9%) of the tumours. Cyclin D1 expression was correlated with tumour grade and stage as well as with the existence of in situ component. In addition, cyclin D1 expression was positively correlated with p21(Waf1/Cip1) and p27(Kip1) and inversely with the Ki-67 score. Focal positivity (<20% of tumour cells) or the absence of cyclin E immunoreactivity was observed in 105/142 (73.9%) in all cases. Cyclin E expression was correlated with tumour stage. A positive relationship between cyclin E expression and the two associated proliferating indices Ki-67 and PCNA, as well as with p53 and p27(Kip1) proteins expression was noted. Absence or focal positivity (<5% of tumour cells) of p21(Waf1/Cip1) was detected in 88/142 (62%) of the carcinomas. p21(Waf1/Cip1) expression was correlated with tumour grade and stage. A positive relationship of its expression cyclin D1, cyclin E, p27 and pRb expression was observed. Absence or focal immunostaining (<20% of tumour cells) of p27 protein was detected in 55/141 (39%) in all cases. p27(Kip1) expression was correlated with tumour grade as well as with cyclins D1 and E. The prognostic significance of cyclins D1, E and cyclin-dependent kinase inhibitors p21(Waf1/Cip1), p27(Kip1) in determining the risk of recurrence and progression with both univariate (log rank test) and multivariate (Cox regression) methods of analysis showed no statistically significance differences. CONCLUSION: These findings suggest that the level of the cell cycle regulators studied does not seem to have a clinical value in terms of predicting the risk of early recurrence and progression. In addition the interrelationship probably means their contribution to the regulation of cell growth through different pathways in bladder carcinogenesis.     

Prognostic implications of aberrations in p16/pRb pathway in urothelial bladder carcinomas: a multivariate analysis including p53 expression and proliferation markers

OBJECTIVE: To assess the prognostic value of the expression of two negative regulators of the cell cycle, namely CDKN2/INK4a gene product (p16) and retinoblastoma gene product (pRb), in urinary bladder cancer in relation to clinicopathological parameters, proliferative fraction and p53 protein accumulation. METHODS: Paraffin sections from 139 patients with urothelial carcinomas were stained immunohistochemically with antibodies to p16 (F12), pRb (PMG3-245), p53 (DO1), PCNA (PC10) and Ki-67 (MIB-1). RESULTS: Diminished p16 and pRb expression occurred in 29 and 74% of cases, respectively, being associated with advanced stage but not with histological grade, papillary status or proliferation rate. In most cases (53%) with some fault in the p16/pRb pathway, only one gene was affected. A double-negative p16/pRb phenotype was comparatively uncommon (25%) and was usually seen in T3-T4 tumours. In survival analysis (either univariate or multivariate) aberrant p16 expression was an adverse prognostic parameter only in T3-T4 tumours. In contrast, the abnormal p16/pRb and p53/p16 phenotypes were linked to a diminished overall and disease-free survival (univariate analysis); p53/p16 abnormal expression was also found to be an independent predictor of reduced survival in muscle-invasive tumours, while proliferation markers were the only parameters with independent significance in superficial (Ta-T1) tumours. CONCLUSION: Our results suggest that lack of p16 immunoexpression, when combined with p53 accumulation, plays an important role in determining the clinical outcome in muscle-invasive urothelial carcinomas.