Human papillomavirus infection and cyclin D1 gene amplification in laryngeal squamous cell carcinoma: biologic function and clinical significance

HPV Status as Prognostic Biomarker in Head and Neck Cancer-Which Method Fits the Best for Outcome Prediction?

The incidence of human papillomavirus (HPV)-related head and neck cancer (HNSCC) is rising globally, presenting challenges for optimized clinical management. To date, it remains unclear which biomarker best reflects HPV-driven carcinogenesis, a process that is associated with better therapeutic response and outcome compared to tobacco/alcohol-induced cancers. Six potential HPV surrogate biomarkers were analyzed using FFPE tissue samples from 153 HNSCC patients (n = 78 oropharyngeal cancer (OPSCC), n = 35 laryngeal cancer, n = 23 hypopharyngeal cancer, n = 17 oral cavity cancer): p16, CyclinD1, pRb, dual immunohistochemical staining of p16 and Ki67, HPV-DNA-PCR, and HPV-DNA-in situ hybridization (ISH). Biomarkers were analyzed for correlation with one another, tumor subsite, and patient survival. P16-IHC alone showed the best performance for discriminating between good (high expression) vs poor outcome (low expression; p = 0.0030) in OPSCC patients. Additionally, HPV-DNA-ISH (p = 0.0039), HPV-DNA-PCR (p = 0.0113), and p16-Ki67 dual stain (p = 0.0047) were significantly associated with prognosis in uni- and multivariable analysis for oropharyngeal cancer. In the non-OPSCC group, however, none of the aforementioned surrogate markers was prognostic. Taken together, P16-IHC as a single biomarker displays the best diagnostic accuracy for prognosis stratification in OPSCC patients with a direct detection of HPV-DNA by PCR or ISH as well as p16-Ki67 dual stain as potential alternatives.

Cyclin D1 Gene Numerical Imbalances in Laryngeal Squamous Cell Carcinoma: A Tissue Microarray Grid Based Analysis

BACKGROUND

Deregulation of critical proteins involved in cell cycle stability, such as cyclins, is a frequent genetic event in the development and progression of solid malignancies. Concerning laryngeal squamous cell carcinoma (LSCC), cyclin D1 oncogenic transformation leads to an aberrant protein expression and seems to affect the biological behaviour of the neoplasm. The aim of this study was to determine the correlation of cyclin D1 numerical imbalances with the corresponding protein expression levels in LSCCs.

MATERIAL AND METHOD

Using tissue microarray (TMA) technology, fifty (n=50) histologically confirmed primary LSSCs were cored at a diameter of 1.5 mm. Immunohistochemistry (IHC) and chromogenic in situ hybridization (CISH) analyses were applied. Concerning the screening process in CISH slides, a novel real-time reference and calibration grid platform was implemented.

RESULTS

Protein overexpression was observed in 22/50 (44%) cases; whereas, gene amplification was seen in 13/50 (26%) cases (p=0.02). Combined protein/ gene deregulation was associated with the stage of malignancy (p= 0.0014, p=0.001), whereas overall protein expression was strongly correlated with the grade of tumour (p= 0.001).

CONCLUSION

Cyclin D1 gene amplification led to aberrant protein expression in LSCCs and it was also correlated with an aggressive biological behaviour. To best of our knowledge, this study was the first described grid based CISH analysis under conventional bright field microscopy for detecting gene numerical imbalances while providing a novel and accurate description for screening-mapping process in the entire slide area.<br />.

Paediatric virology and human papillomaviruses: An update

Almost 10 years ago, in October, 2008, the scientist who reported for the first time the association between human papillomaviruses (HPV) and cervical cancer, was awarded with the Nobel prize. In the years that followed, Professor Harald zur Hausen actively supported the value of the HPV vaccination in the prevention of different types of cancer and highlighted the necessity of its introduction in both girls and boys. However, to date, in the majority of countries, HPV vaccination among male adolescents has not been implemented into the national vaccination schemes, while in several countries, including Greece, the participation rate to HPV vaccination among female adolescents still remains low. Recent data indicate that catch-up HPV vaccination among young women has been extremely useful and has exhibited a significant effect in decreasing the prevalence of HPV. While the marketed current HPV vaccines prevent anogenital HPV infection, their impact on the natural history of oral HPV and their efficacy in preventing HPV-related head and neck carcinomas need to be further investigated. Juvenile onset recurrent respiratory papillomatosis, as well as HPV-associated conjunctival papillomas continue to be observed in childhood and their clinical management involves different therapeutic approaches with controversial outcomes. This review article provides an overview of recent views and advances on HPV infections and prevention in childhood that were presented at the '4th Workshop on Paediatric Virology' on Saturday September 22, 2018 in Athens, Greece.

An updated overview of HPV-associated head and neck carcinomas

Human papilloma virus (HPV)-associated head and neck carcinoma is quite heterogeneous and most of the tumors arise in the oral cavity, oropharynx, hypopharynx and larynx. HPV was just recently recognized as an emerging risk factor for oropharyngeal squamous cell carcinoma (OSCC). HPV(+) tumors represent 5-20% of all head and neck squamous-cell carcinomas (HNSCCs) and 40-90% of those arising from the oropharynx, with widely variable rates depending on the geographic area, population, relative prevalence of environment-related SCC and detection assay. Different carcinogenic mechanisms are most likely implicated in cervical and oropharyngeal carcinogenesis. The most certain carcinogenic genotype for the head and neck region and the most common high-risk HPV genotype, HPV-16, is frequently detected in OSCC. A combination of p16INK4A expression and molecular detection of HPV DNA is the gold standard for the viral identification in tissue and exfoliated cell samples. Differences in the biology of HPV(+) and HPV(-) OSCC may have implications for the management of patients. New immunotherapy drugs based on the release of the co-inhibitory receptors, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed-death 1 (PD-1) have currently emerged. The goal of therapeutic cancer vaccination is inculcation of a persistent, tumor antigen-specific T cell response which kills tumor cells. The efficacy of the current HPV vaccines, Cervarix and Gardasil, in preventing HPV-related HNSCC is at present unknown. Treatment de-escalation is recommended as the current management of HPV-induced HNSCCs.

Human papillomavirus prevalence and cell cycle related protein expression in tonsillar squamous cell carcinomas of korean patients with clinicopathologic analysis

Background

Human papillomavirus (HPV)-related tonsillar squamous cell carcinoma (TSCC) has recently been characterized as a distinct subset with a favorable prognosis. The prevalence and clinicopathologic significance of HPV-related TSCC in Koreans are not well known.

Methods

HPV in situ hybridization (ISH) accompanied by p53, p16, pRb, and cyclin D1 immunohistochemical staining were performed on 89 resection cases of TSCC from 2000 through 2010.

Results

HPV was detected by ISH in 59 of 89 cases (66.3%). HPV-positive TSCCs were more common in younger ages (p=0.005), and tumor sizes were smaller in the HPV-positive compared to the HPV-negative group (p=0.040). Positive HPV staining was significantly correlated with p16 expression (p<0.001), pRb inactivation (p=0.003), and cyclin D1 down-regulation (p<0.001) but not with p53 expression (p=0.334). Seventeen cases that showed p16-immunopositivity with HPV-negativity by ISH were retested by HPV typing; HPV DNA was not detected in all cases. There was no significant difference between HPV-positive and HPV-negative patients either in the disease-specific survival (DSS, p=0.857) or overall survival (p=0.910). Furthermore, pRb-inactivated cases showed better DSS (p=0.023), and p53-positive cases showed worse DSS (p=0.001).

Conclusions

Although high HPV prevalence was noted, it was not correlated with histopathologic findings or survival benefit. In addition to p53 expression, pRb inactivation along with p16 overexpression and down-regulation of cyclin D1 are thought to be important pathogenetic steps for developing TSCCs.

HPV infection in squamous cell carcinomas arising from different mucosal sites of the head and neck region. Is p16 immunohistochemistry a reliable surrogate marker?

BACKGROUND

Human papillomavirus 16 infection has been proven to be associated with oropharyngeal squamous cell carcinomas (SCCs) and is probably the main reason of the reported increase in the incidence. The role of high-risk (HR) HPV for carcinogenesis of other sites in the head and neck awaits confirmation. With the aim to evaluate the prevalence of HPV infection and the reliability of different diagnostic tools in SCCs of different sites, 109 consecutive untreated head and neck SCCs were enrolled, and fresh tumour samples collected.

METHODS

Human papillomavirus DNA was detected by Digene Hybrid Capture 2 (HC2). Human papillomavirus E6 and E7 mRNA were detected by NucliSENS EasyQ HPVv1. P16 expression was evaluated by immunohistochemistry.

RESULTS

In all, 12.84% of cases were infected by HR genotypes and 1.84% by low-risk genotypes. Human papillomavirus 16 accounted for 87% of HR infections. The overall agreement between DNA and RNA detection is 99.1%. Although p16 expression clearly correlates with HPV infection (P=0.0051), the inter-rater agreement is poor (k=0.27). The oropharynx showed the highest HR HPV infection rate (47.6%) and was also the only site in which p16 immunohistochemistry revealed to be a fair, but not excellent, diagnostic assay (κ=0.61).

CONCLUSION

The prognostic role of HR HPV infection in oropharyngeal oncology, with its potential clinical applications, underscores the need for a consensus on the most appropriate detection methods. The present results suggest that viral mRNA detection could be the standard for fresh samples, whereas DNA detection could be routinely used in formalin-fixed, paraffin-embedded samples.

p16 INK4A overexpression is frequently detected in tumour-free tonsil tissue without association with HPV

AIMS

Oncogenic human papillomavirus (HPV) type 16 has been strongly associated with tonsillar squamous cell carcinoma (TSCC) and appears to be of prognostic significance. Because HPV+ TSCC also accumulates p16(INK4A), this cyclin-dependent kinase inhibitor has been proposed as a potential biomarker for HPV in clinical diagnosis. The aim of this study was to determine the prevalence of HPV in tumour-free tonsillar tissue and the value of p16(INK4A) overexpression in predicting its presence.

METHODS AND RESULTS

p16(INK4A) overexpression was detected by immunohistochemistry in tissue sections of tumour-free tonsils of 262 patients. They were treated for non-oncological reasons (snoring or chronic/recurrent tonsillitis) consisting of tonsillectomy. Genomic DNA isolated from these tissues was subjected to HPV-specific polymerase chain reaction (PCR) analysis. p16(INK4A) immunoreactivity was detected in 28% of samples in both crypt epithelium (49/177) and lymphoid germinal centres (52/187), which correlated with each other (P < 0.0001). No reactivity was observed in superficial squamous cell epithelium. HPV16 and 18 were detected by PCR analysis in 2/195 cases (1%), which, however, were negative on fluorescence in situ hybridization analysis and discrepant on p16(INK4A) immunostaining.

CONCLUSIONS

No proof was found for the presence of HPV in tumour-free tonsil tissue, despite increased p16(INK4A) expression in a quarter of tonsil cases. Other mechanisms than HPV infection are therefore implicated in p16(INK4A) up-regulation.

P21 Cip1/WAF1 expression is strongly associated with HPV-positive tonsillar carcinoma and a favorable prognosis

Human papillomavirus is involved in the carcinogenesis of tonsillar squamous cell carcinomas. Here, we investigated the expression and the prognostic value of key cell cycle proteins in the pRb and p53 pathways in both human papillomavirus type 16-positive and -negative tonsillar squamous cell carcinomas. Using immunohistochemistry, 77 tonsillar squamous cell carcinomas with known human papillomavirus type 16 status and clinical outcome were analyzed for expression of Ki67, p16(INK4A,) cyclin D1, pRb, p14(ARF), MDM2, p53, p21(Cip1/WAF1), and p27(KIP1). Results were correlated with each other and with clinical and demographic patient data. A total of 35% of tonsillar carcinomas harbored integrated human papillomavirus type 16 DNA and p16(INK4A) overexpression, both being considered essential features for human papillomavirus association. These tumors also showed the overexpression of p14(ARF) (P<0.0001) and p21(Cip1/WAF1) (P=0.001), and downregulation of pRb (P<0.0001) and cyclin D1 (P=0.027) compared with the human papillomavirus-negative cases. Univariate Cox regression analyses revealed a favorable survival rate for non-smokers (P=0.006), as well as for patients with T1-2 tumors (P<0.0001) or tumors showing low expression of cyclin D1 (P=0.028), presence of human papillomavirus and overexpression of p16(INK4A) (P=0.01), p14(ARF) (P=0.02) or p21(Cip1/WAF1) (P=0.004). In multivariate regression analyses, smoking and tumor size, as well as expression of cyclin D1 and p21(Cip1/WAF1), were found to be independent prognostic markers. We conclude that human papillomavirus positivity in tonsillar squamous cell carcinomas strongly correlates with p21(Cip1/WAF1) and p14(ARF) overexpression and downregulation of pRb and cyclin D1. In particular p21(Cip1/WAF1) overexpression is an excellent favorable prognosticator in tonsillar squamous cell carcinomas.

Should there be more molecular staging of head and neck cancer to improve the choice of treatments and thereby improve survival?

PURPOSE OF REVIEW

Overall survival of head and neck squamous cell carcinoma patients on the whole has not dramatically improved in the last 30 years. One of the reasons is that tumour, node, metastasis classification is probably in some cases inadequate, since similar cases under a clinico-pathological point of view, may differ widely in prognosis. The most important reason for this is probably the extreme biological heterogeneity, which leads to a lack of consistency in treatment planning. The aim of the present review is to delineate the advances and the perspectives of clinical use of molecular characterization, which is an attempt to break through such molecular heterogeneity and to define, together with tumour, node, metastasis classification, homogeneous groups of patients for prognostic stratification and treatment selection.

RECENT FINDINGS

Among the markers evaluated in the last years, some have revealed particular promise. Epidermal growth factor receptor is probably the most reliable molecular marker at present, retaining its prognostic value independently from primary treatment. The p53 gene, the p53 protein being the main effector of DNA damage induced apoptosis, is probably the best predictor of radio/chemosensitivity.

SUMMARY

Even if clinical tumour, node, metastasis classification will probably retain its significance, it is now becoming possible, by molecular markers, to acquire biological information about host and tumour, to break through the above-cited molecular heterogeneity and eventually to optimize the choice of treatment.

Critical role for D-type cyclins in cellular transformation induced by E6/E7 of human papillomavirus type 16 and E6/E7/ErbB-2 cooperation

Recently, we reported that E6/E7 of human papillomavirus (HPV) type 16 cooperates with the ErbB-2 receptor to induce cellular transformation of human normal oral epithelial (NOE) and mouse normal embryonic fibroblast (NEF) cells. Furthermore, we demonstrated that cyclin D1 is essential for this transformation induced by E6/E7 and E6/E7/ErbB-2 cooperation using cyclin D1 antisense and knockout (D1(-/-)) cells. To determine the role of all D-type cyclins (D1, D2 and D3) in E6/E7/ErbB-2 cooperation, we examined the effects of E6/E7, ErbB-2 alone and E6/E7/ErbB-2 together in NEF, NEF-D1(-/-), NEF-D2(-/-) and NEF-D3(-/-) cells. We confirm that NEF-E6/E7 and NEF-E6/E7/ErbB-2, but not NEF-ErbB-2 cells, induce colony formation in soft agar and tumor formation in nude mice. We report that E6/E7, ErbB-2 and E6/E7/ErbB-2 together all fail to induce neoplastic transformation of D1(-/-) and D2(-/-) cells in vitro and in vivo. In contrast, E6/E7/ErbB-2 together but neither E6/E7 nor ErbB-2 alone provoke cellular transformation of D3(-/-) cells. Nevertheless, D3(-/-)E6/E7/ErbB-2 cells resulted in up to a 60 and 50% decrease in colony and tumor formation in soft agar and nude mice, respectively, compared with NEF-E6/E7/ErbB-2 cells. Furthermore, using cyclin D2 small interfering RNA we inhibited tumor and colony formation of the human NOE-E6/E7-ErbB-2-transformed cell line; in contrast, cyclin D3 small interfering RNA repressed approximately 50% of colony and 40% of tumor formation of E6/E7/ErbB-2 cooperation in this cell line. These data suggest that cyclins D1, D2 and D3 (to a lesser extent) are important downstream mediators of the cellular transformation induced by E6/E7 and E6/E7/ErbB-2 cooperation in normal cells. Our data imply that anti-D-type cyclin therapies are important in the treatment of human cancers expressing high-risk HPV or HPV/ErbB-2.

Detection of CCND1 amplification using laser capture microdissection coupled with real-time polymerase chain reaction in human esophageal squamous cell carcinoma

Several methods have been used to detect CCND1 amplification or overexpression in esophageal squamous cell carcinoma (ESCC), but problems remain, associated with heterogeneity of tumor tissue and quantification of gene copies. Laser capture microdissection coupled with real-time polymerase chain reaction (PCR) is a reliable method for the molecular analysis of gene profiles in specific tissues. All 35 specimens of ESCC studied were paraffin-embedded, cut into tissue slides, and stained by hematoxylin-eosin. The pure ESCC cell and normal squamous epithelia populations were separated by LCM and then genomic DNA was extracted from the dissected cells. CCND1 amplification was detected with real-time FQ-PCR and with PCR. Amplification was calculated by the formula X = 2(-DeltaDeltaCt) and R = (CCND1/ACTB) CANCER/(CCND1/ACTB) NORMAL. Twenty (57%) of primary ESCC cancer cell groups had a detectable CCND1 amplification (range, 2.06-fold to 25.9-fold) with real-time FQ-PCR, but only 2 of 15 primary ESCC cancer cell groups had detectable CCND1 amplification by PCR. CCND1 amplification was not correlated with age, sex, size of tumor, histological grade, and lymph node metastasis. In conclusion, LCM coupled with real-time fluorescence quantitative-PCR technique is more precise than PCR for the identifying amplified oncogenes; The role of CCND1 amplification in ESCC development and progression needs more extensive study.

Environmental risk factors for prevention and molecular intervention of cervical cancer

Cervical cancer (CC) is potentially the most preventable and treatable cancer in human but it is a leading cause for cancer morbidity and mortality in women around the world. Therefore, more innovative prevention and treatment protocols need to be developed and implemented. With better understanding of the etiology of the disease, specific prevention protocols that involve life-style modifications to minimize the impact of environmental risk factors can be developed. It may be necessary to implement unique modification protocols for different countries. In addition, antiviral vaccine is a highly promising prevention approach. With respect to therapy, the development of more specific protocols that have fewer side effects is needed. With the availability of sophisticated molecular techniques, a new generation of targeted approach that has the potential to generate outstanding efficacy is being tested. Using the siRNA technology against the expression of human papillomavirus oncogenes, specific biological pathways that are essential to the growth and survival of the CC cells can be interrupted. Another promising approach is the molecular intervention of the estrogen pathway by blocking the expression of estrogen receptors. These molecular techniques may work by reactivating endogenous regulatory processes, e.g., the core apoptotic machinery, that can cause self-destruction of the CC cells, thus providing potentially effective molecular therapy. These topics are discussed in this review.

Inhibition of growth of cervical cancer cells using a dominant negative estrogen receptor gene

OBJECTIVE

Estrogen stimulates human papilloma virus oncogene expression, promotes cervical cancer (CC) cell proliferation and prevents apoptosis. Therefore, blockage of estrogen function may have therapeutic application to CC.

METHODS

CasKi CC cells were transfected with an adenovirus expressing a dominant negative estrogen receptor gene (Ad-ER-DN) and their responses were investigated by RT-PCR, Flow Cytometry and Western blot assays.

RESULT

Transfected cells showed disturbance of cell colony morphology, reduced HPV E6 and E7 mRNA, interruption of cell proliferation, reduced cyclin D1 protein and expression of apoptosis.

CONCLUSION

We report, for the first time, the use of Ad-ER-DN to block estrogen receptors which led to dramatic changes in CC cells that are consistent with the possible reactivation of cellular p53 and Rb function. Their reactivation most likely allowed the recognition of existing chromosome abnormalities as a serious stress signal and the initiation of a cascade of cellular events in response to the stress, including the activation of the core apoptotic machinery which led to self-destruction of the CC cells.

Genetic Alterations (Amplification and Rearrangement) of D-Type Cyclins Loci in Head and Neck Squamous Cell Carcinoma of Indian Patients

In this study, the alterations (amplification/rearrangement) of 3 D-type cyclins loci were analyzed by Southern blot in 5 dysplastic head and neck lesions and 79 primary head and neck squamous cell carcinoma (HNSCC) of Indian patients to understand the role of the cyclins in development of the disease. No alteration was found in the dysplastic lesions. Overall, 54% of alterations were found in bcl-1/CCND1 locus, whereas amplification was only found in CCND2 and CCND3 loci in 12% and 2% samples, respectively. In bcl-1/CCND1 locus amplification was the major type of alteration; however, rearrangement as well as coalterations had been seen in some samples indicating the common mechanism of activation of this locus in different types of tumors. In bcl-1 region, the breakpoint clustered in the MTC (major translocation cluster) region, whereas in CCND1 the breakpoint located near 3' end of the gene. The coamplification of CCND2 locus with bcl-1, bcl-1/CCND1, and CNND3 loci suggests cumulative effect of these genes in this tumor. The significant association was seen between bcl-1/CCND1 locus alteration with HPV prevalence and poor patient outcome indicating its importance as prognostic marker. This indicates that the genetic instability caused due to HPV infection may induce the alterations in the bcl-1/CCND1 locus, which will provide selective growth advantage to the specific malignant clones resulting poor prognosis of the disease.

[The relationship between human papillomavirus and cyclin D1 gene amplification in squamous cell carcinomas of the head and neck]

INTRODUCTION

infection by oncogenic subtypes of human papillomavirus (HPV) and cyclin D1 gene (CCND1) amplification are frequent events in head and neck squamous cell carcinomas. The objective of this paper is to establish the relationship between the presence of human papillomavirus (HPV) gene sequences and the development of CCND1 gene amplification in these tumours.

MATERIALS AND METHODS

59 squamous cell carcinomas of the head and neck were studied for HPV types 6b and 16 and CCND1 gene amplification by polymerase chain reaction.

RESULTS

HPV DNA was detected in 14 tumors (24%). Ten of them were positive for the HPV type 6b and 4 for the HPV type 16. CCND1 gene amplification was found in 15 cases (25%). Although we have found a higher frequency of CCND1 amplification in the HPV-positive cases (36%, versus 22% in the HPV-negative cases), these differences were not statistically significant (P= 0,32).

CONCLUSIONS

The presence of HPV gene sequences does not seem to be related to a significative higher incidence of CCND1 gene amplification in the squamous cell carcinomas of the head and neck.

Molecular markers in laryngeal squamous cell carcinoma: towards an integrated clinicobiological approach

Of the most frequent malignancies in the United States, cancers of the larynx and of the uterine corpus are the only ones not to show an increase in 5-year survival rates over the last 30 years. The increasing use of chemo- and radiotherapy and conservative surgery to preserve organs and their functions has probably led to a better quality of life in patients with laryngeal cancer, but has definitely failed to improve survival, which remains the primary aim. In our opinion, to reduce laryngeal cancer-related mortality, a change in clinical approach is required. We have reviewed the literature on the potential role of molecular markers in the clinical management of laryngeal cancer. We believe that some of the most significant biological markers might be integrated with the evaluation of behavioural risk factors, clinical TNM staging and histopathological grading for a novel clinicomolecular approach to laryngeal cancer. We foresee the use of the most promising biological markers in the phases of prevention, diagnosis, prognostic assessment and drug design.

Different risk factors in basaloid and common squamous head and neck cancer

OBJECTIVES/HYPOTHESIS

The prevalence of human papillomavirus (HPV), herpes simplex virus (HSV), cigarette smoking and alcohol abuse was compared between two histological subgroups of head and neck cancer.

STUDY DESIGN

Retrospective review.

METHODS

Paraffin-embedded, histologically confirmed surgical specimens from the oropharynx, hypopharynx and larynx, comprising 67 conventional squamous cell carcinomas (SCC) and 10 basaloid squamous cell carcinomas (BSCC), were analyzed for the presence of HPV and HSV DNA using polymerase chain reaction (PCR) techniques. The PCR products were verified by direct sequencing. Patient charts were reviewed for clinical data and risk factors.

RESULTS

Given an overall HPV DNA detection rate of 32.5%, a basaloid morphology of the carcinomas correlated significantly with occurrence of HPV DNA (P =.0001). An association could also be demonstrated between basaloid appearance and evidence of HSV DNA (single and combined with HPV DNA; P =.014 and 0.0429, respectively), even if this result based on a low overall HSV DNA detection rate (6.5%). Demonstration of viral DNA in the BSCC specimens was not related to tobacco or alcohol consumption. In contrast, cigarette smoking proved as significant characteristic of SCC (P =.0087). Alcohol abuse occurred also predominately in patients with SCC, but without statistical significance.

CONCLUSION

These results hint at differences in the etiology of two distinct histological entities of head and neck cancer. Further research in this field could complete these preliminary data and provide the background for specific preventive strategies.

Cyclin D1 is essential for neoplastic transformation induced by both E6/E7 and E6/E7/ErbB-2 cooperation in normal cells

More than 25% of head and neck squamous cell carcinomas (HNSCC) and 99% of cervical cancers (CxCa) are positive for high-risk human papillomaviruses (HPVs). Furthermore, the type I tyrosine kinase receptor ErbB-2 is overexpressed in at least 30% of HNSCC and CxCa. Recently, we demonstrated that E6/E7 of HPV type 16 cooperate with ErbB-2 to induce cell transformation of human normal oral epithelial (NOE) cells. This is accompanied by overexpression of cyclin D1 in NOE cells. To determine the role of cyclin D1 in E6/E7/ErbB-2 cooperation, we examined the independent effects of E6/E7 and ErbB-2, and the combined effect of E6/E7 and ErbB-2 in mouse normal embryonic fibroblast (NEF), wild type (wt), and knockout cyclin D1 (D1(-/-)) cells. We report that NEF-wt cells transduced with E6/E7 alone and E6/E7/ErbB-2 together form small and large tumors in nude mice, respectively, as well as different sized colonies in soft agar; whereas ErbB-2 alone elicits neither tumor formation in vivo nor colony formation in soft agar. More importantly, E6/E7, ErbB-2 and E6/E7/ErbB-2 together all fail to induce neoplastic transformation of cyclin D1(-/-) cells in vivo and in vitro. Furthermore, using antisense cyclin D1 we completely inhibited tumor and colony formation of NEF-wt-E6/E7 and wt-E6/E7-ErbB-2 as well as human NOE-E6/E7-ErbB-2-transformed cells. These analyses reveal that cyclin D1 is the downstream target of the neoplastic transformation induced by E6/E7 or E6/E7/ErbB-2 cooperation in normal cells. Our data suggest that anti-cyclin D1 therapy may be highly specific in the treatment of all human cancers expressing high-risk HPVs or HPVs/ErbB-2.

Human papillomavirus infection in the etiology of laryngeal carcinoma

PURPOSE OF REVIEW

One fifth of cancers worldwide are associated with viral infection. Indeed, the causal link between human papillomavirus and cervical carcinoma is so well established that it is thought to be the first necessary cause of human cancer ever identified. One of the primary aims of research in this area is to reduce cancer prevalence by vaccination. However, the role that human papillomavirus plays in carcinogenesis of the head and neck region may also have important implications for its prevention and treatment.

RECENT FINDINGS

Although human papillomavirus was first identified in the larynx 20 years ago, the extent to which it is present in epithelium of the normal population is unclear. Laryngeal papillomas are the most common benign tumors in the larynx. They are associated with a small risk (3 to 7%) of malignant transformation, in which smoking and irradiation appear to be cofactors. The search for alternate risk factors for the development of laryngeal cancer, particularly in those who are nonsmokers and nondrinkers, has led to the hypothesis that human papillomavirus may have a pivotal role. Epidemiologic studies, although not conclusive, strongly suggest its involvement in the etiology of a subset of laryngeal carcinomas. Recent molecular evidence supports this.

SUMMARY

An adequately powered, multicenter case-control study is required to elucidate the full extent of this association and to examine the relation between the virus and other risk factors.

Relationship between cyclin D1 and p21(Waf1/Cip1) during differentiation of human myeloid leukemia cell lines

Expression of cell cycle-regulating genes was studied in human myeloid leukemia cell lines ML-1, ML-2 and ML-3 during induction of differentiation in vitro. Myelomonocytic differentiation was induced by phorbol ester (12-o-Tetradecanoyl-phorbol-13-acetate, TPA), tumor necrosis factor alpha (TNFalpha) or interferon gamma (INFgamma), or their combination. Differentiation (with the exception of TNFalpha alone) was accompanied by inhibition of DNA synthesis and cell cycle arrest. Inhibition of proliferation was associated with a decrease in the expression of cdc25A and cdc25B, cdk6 and Ki-67 genes, and with increased p21(Waf1/Cip1) gene expression, as measured by comparative RT-PCR. Expression of the following genes was not changed after induction of differentiation: cyclin A1, cyclin D3, cyclin E1 and p27(Kip1). Surprisingly, cyclin D1 expression was upregulated after induction by TPA, TNFalpha with IFNgamma or BA. Cyclin D2 was upregulated only after induction by BA. The results of the expression of the tested genes obtained by comparative RT-PCR were confirmed by quantitative real-time (RQ) RT-PCR and Western blotting. Quantitative RT-PCR showed as much as a 288-fold increase of cyclin D1 specific mRNA after a 24h induction by TPA. The upregulation of cyclin D1 in differentiating cells seems to be compensated by the upregulation of p21(Waf1/Cip1). These results, besides others, point to a strong correlation between the expression of cyclin D1 and p21(Waf1/Cip1) on the one hand and differentiation on the other hand in human myeloid leukemic cells and reflect a rather complicated network regulating proliferation and differentiation of leukemic cells.

Current theories for the development of nonsmoking and nondrinking laryngeal carcinoma

The pivotal risk of smoking and alcohol in laryngeal cancer has meant that evidence for alternate cofactors has been indicative to date. A number of case series, however, contain a few patients who are life-long nondrinkers and nonsmokers and question what other cofactors may contribute. Gastroesophageal reflux disease makes a small but significant contribution to the causal development of laryngeal cancer; however, what remains to be understood is the mechanism of its action. Bile reflux appears to be an additional causative factor in achlorhydrics. After controlling for the effects of alcohol and tobacco, exposure to oncogenic types of human papilloma virus is associated with an increased risk of laryngeal carcinoma. Evidence does not support asbestos exposure itself as increasing the relative risk of laryngeal cancer. A dietary increase in vegetables and fruit may confer an advantage in reducing the laryngeal cancer incidence. Inherited differences in cell cycle control systems, DNA repair systems, and carcinogen-metabolizing enzymes can increase the risk for laryngeal cancer, but as yet, no causal mechanism has been demonstrated.