Reduced expression of cyclin-dependent kinase inhibitor p27Kip1 is an indicator of malignant behavior in oral squamous cell carcinoma

Clinicopathological and Prognostic Significance of p27 Expression in Oral Squamous Cell Carcinoma: A Meta-Analysis

Despite being already known that p27 can regulate cell proliferation, cell motility and apoptosis, the role of p27 expression in oral squamous cell carcinoma (OSCC) remains controversial. The purpose of this study was to comprehensively evaluate, with a meta-analysis, the clinicopathological and prognostic role of p27 expression in OSCC. A meta-analysis of eligible studies was performed to assess the effects of p27 expression on clinicopathological parameters and overall survival (OS) in patients with OSCC, using pooled relative risks with 95% confidence intervals. Heterogeneity and publication bias were also assessed. Fourteen studies involving a total of 1,010 patients met the inclusion criteria. Low p27 expression was significantly associated with advanced TNM stage (p<0.001), worse histology (p=0.025), and lymph node metastasis (p<0.001), but not with tumor size (p=0.181). The pooled RR of 0.743 (p=0.002) suggested that low p27 expression has a poor prognosis in patients with OSCC. A significant heterogeneity among studies was detected for lymph node status (χ2=34.60, I2=68.2%, p<0.001) and OS (χ2=14.86, I2=39.4%, p=0.095). We did not detect a significant publication bias in this meta-analysis. Our meta-analysis suggests that p27 expression status might be useful as a predictive biomarker in clinical practice, and might potently predict OS in OSCC patients.

Expression of Cell Cycle-associated Proteins p53, pRb, p16, p27, and Correlation With Survival: A Comparative Study on Oral Squamous Cell Carcinoma and Verrucous Carcinoma

Verrucous carcinoma (VC) is a well-differentiated form of squamous cell carcinoma (SCC) with better prognosis. Differences in molecular pathogenesis between the 2 have not been well-characterized. We conducted this study to evaluate immunohistochemical expression of cell-cycle regulatory proteins p53, pRb, p16, and p27 in SCC and VC, compare the expression in these 2 neoplasms, and assess if these markers have any diagnostic or prognostic value. Sixty cases of SCC with and without lymph node metastasis and 31 cases of VC were studied. Immunohistochemical analysis for p53, pRb, p16, and p27 was performed and the results were analyzed. SCC was most frequent in tongue (52%), whereas VC in buccal mucosa (81%). Mean age of SCC patients was significantly lower than in VC. Majority of SCCs were in stage III and IV (63%), whereas VCs were in stage I and II (84%). p53 immunopositivity was more frequent in SCC (65%) than in VC (23%) (P≤0.001). VC had lower p53 as compared with well-differentiated SCC and SCC without lymph node metastasis. No significant difference was seen in pRb, p16, and p27 expression. Disease-free survival (DFS) at 1 year for SCC was 57% whereas it was 80% for VC (P=0.02). DFS and overall survival of SCC correlated with nodal status and stage; cell-cycle-associated protein expression had no association with DFS. To conclude, p53 immunoexpression differs in SCC and VC, suggesting different pathogenesis, and it may have some utility as an adjunct to morphology to differentiate between the 2. Expression of cell-cycle-associated proteins does not influence survival in SCC.

Prognostic value of some tumor markers in unresectable stage IV oropharyngeal carcinoma patients treated with concomitant radiochemotherapy

Background

The aim of the study was to investigate how the expression of tumor markers p21, p27, p53, cyclin D1, EGFR, Ki-67, and CD31 influenced the outcome of advanced inoperable oropharyngeal carcinoma patients, treated with concomitant radiochemotherapy.

Patients and methods.

The pretreatment biopsy specimens of 74 consecutive patients with inoperable stage IV oropharyngeal squamous cell carcinoma treated with concomitant radiochemotherapy were in retrospective study processed by immunochemistry for p21, p27, p53, cyclin D1, EGFR, Ki-67, and CD31. Disease-free survival (DFS) was assessed according to the expression of tumor markers.

Results

Patients with a high expression of p21 (≥10%), p27 (>50%), Ki-67 (>50%), CD31 (>130 vessels/mm2) and low expression of p53 (<10%), cyclin D1 (<10%) and EGFR (<10%) (favorable levels - FL) had better DFS than patients with a low expression of p21 (<10%), p27 (≤50%), Ki-67 (≤50%), CD31 (<130 vessels/mm2) and high expression of p53 (≥10%), cyclin D1 (≥10%) and EGFR (≥10%) (unfavorable levels - UL). However, statistical significance in survival between FL and UL was achieved only for p27 and cyclin D1. DFS significantly decreased with an increasing number of markers with an unfavorable level per tumor (1–4 vs. 5–7) (78% vs. 32%, respectively; p = 0.004). The number of markers per tumor with UL of expression retained prognostic significance also in multivariate analysis.

Conclusions

Statistical significance in survival between FL and UL emerged only for p27 and cyclin D1. The number of markers per tumor with UL of expression was an independent prognostic factor for an adverse outcome.

p27Kip1 expression as a prognostic marker for squamous cell carcinoma of the head and neck

Regulation of the cell cycle is essential for carcinogenesis. The cell cycle is controlled by cyclin-dependent kinases (CDKs), which are upregulated by cyclins and downregulated by CDK inhibitors (CDKIs). Decreased p27^Kip1 expression has been associated with survival rate, tumor size, histological differentiation and the presence of lymph node metastasis in patients with various types of cancer. The aim of the current study is to provide a literature review on the association between p27^Kip1 expression and the clinical and pathological aspects of head and neck squamous cell carcinoma (HNSCC), and the expression of other CDKIs of the Cip/Kip family and cyclins. Throughout the literature, different methodologies were used to determine the immunohistochemical expression of p27^Kip1; thus, results concerning p27^Kip1 expression in HNSCC vary widely. However, it has now been confirmed that p27^Kip1 is underexpressed in SCC cells. p27 may be a promising marker for determining the prognosis of HNSCC, despite the marked variability of the results obtained. An association between p27 expression and survival rate, time to recurrence and tumor stage has been observed. Based on the information currently available, it is premature to recommend the analysis of p27^Kip1 expression in guiding HNSCC treatment planning. However, although relatively unstudied, the correlation between p27^Kip1 expression and other tumor suppressor genes may turn out to be important in determining the prognosis of HNSCC. Further prospective studies utilizing standardized laboratory methodologies and statistics that facilitate meta-analyses are required to confirm this proposal.

c-Jun, pc-Jun, and p27 are differently expressed in oral leukoplakias in smokers and never-smokers

OBJECTIVE

Oral cancer may be preceded by potentially malignant lesions, and smoking is a risk factor. Oral leukoplakia (OL), which is the most common among these lesions, is defined by the World Health Organization as "a white plaque of questionable risk having excluded known diseases or disorders that carry no increased risk for cancer." Thus, OL is a clinical diagnosis used to designate oral white lesions, which are histologically represented by hyperkeratosis associated or not associated with epithelial dysplasia. It is known that c-Jun and pc-Jun have a role in cell proliferation and that p27 is decreased during carcinogenesis; thus, the aim of this study was to investigate whether these proteins are differently expressed in OL in smokers and never-smokers.

STUDY DESIGN

Seventy-three cases diagnosed as OL were selected and divided into four groups according to the presence or absence of dysplasia and patients' smoking status (smokers: 39 cases, 24 dysplastic; never-smokers: 34 cases, 20 dysplastic). The immunoexpressions of c-Jun, pc-Jun, and p27 were evaluated.

RESULTS

A significant correlation between smoking condition and the percentages of c-Jun (P = .0356) and pc-Jun (P = .0216) was found and was more intense in cases that underwent malignant transformation (6/47).

CONCLUSIONS

Smoking habits may be linked to the expression of proteins directly associated with cell cycle progression.

Overexpression of LIM and SH3 Protein 1 leading to accelerated G2/M phase transition contributes to enhanced tumourigenesis in oral cancer

BACKGROUND

LIM and SH3 protein 1 (LASP-1) is a specific focal adhesion protein involved in several malignant tumors. However, its role in oral squamous cell carcinoma (OSCC) is unknown. The aim of this study was to characterize the role and molecular status/mechanism of LASP-1 in OSCC.

METHODS

We evaluated LASP-1 mRNA and protein expressions in OSCC-derived cell lines and primary OSCCs. Using an shRNA system, we analyzed the effect of LASP-1 on the biology and function of the OSCC cell lines, HSC-3 and Ca9-22. The cells also were subcutaneously injected to evaluate tumor growth in vivo. Data were analyzed by the Fisher's exact test or the Mann-Whitney U test. Bonferroni correction was used for multiple testing.

RESULTS

Significant up-regulation of LASP-1 was detected in OSCC-derived cell lines (n = 7, P<0.007) and primary OSCCs (n = 50, P<0.001) compared to normal controls. LASP-1 knockdown cells significantly inhibited cellular proliferation compared with shMock-transfected cells (P<0.025) by arresting cell-cycle progression at the G2 phase. We observed dramatic reduction in the growth of shLASP-1 OSCC xenografts compared with shMock xenografts in vivo.

CONCLUSION

Our results suggested that overexpression of LASP-1 is linked closely to oral tumourigenicity and further provide novel evidence that LASP-1 plays an essential role in tumor cellular growth by mediating G2/M transition.

Immunohistochemical evaluation of oral epithelial dysplasia using cyclin-D1, p27 and p63 expression as predictors of malignant transformation

OBJECTIVE

To evaluate the degree of expression of cyclin-D1, p27 and p63 in mild, moderate and severe dysplasia using immunohistochemical evaluation in order to illustrate their prognostic value and attempt to propose a molecular grading system for oral epithelial dysplasia.

MATERIALS AND METHODS

The analysis included thirty cases of mild, moderate and severe dysplasia from Department of Oral and Maxillofacial Pathology, Saveetha Dental College, Chennai after a critical review of the Hematoxylin and Eosin (H and E) stained sections. They were subjected to immunohistochemical evaluation using the markers cyclin-D1, p27 and p63. The assessment of the expression based on staining intensity and distribution of immunohistochemical staining of the various markers was analyzed followed by statistical analysis.

RESULTS

A highly significant increase in the expression of cyclin-D1 (P < 0.000) and p63 (P < 0.001) and a moderately significant decrease in the expression of p27 (P < 0.012) with the increasing severity of dysplasia was observed in our study.

CONCLUSIONS

The result of our research affirms the fact that the increase in the expression of markers of cell cycle regulators such as cyclin D1, decrease in the expression of cell cycle inhibitors like p27 and increased expression of p63 in parallel with the increasing severity of dysplasia, emphasizes the use of immunohistochemical markers cyclin D1, p27 and p63 as prognostic markers for better understanding the behaviour of these potentially malignant disorders aiming towards proposing a molecular grading system for oral epithelial dysplasia to enable timely management prior to their possible malignant transformation.

Combined cytoplasmic and membranous EGFR and p53 overexpression is a poor prognostic marker in early stage oral squamous cell carcinoma

OBJECTIVE

Our aim was to evaluate the expression of several molecules that regulate growth, the cell cycle and signalling pathways including EGFR, p53, p16 and p27 in oral squamous cell carcinomas (OSCC). We examined their utility as prognostic markers by relating to clinicopathological characteristics and the clinical outcome.

PATIENTS AND METHODS

Using tissue microarray technology, we analysed 67 primary OSCC and examined immunohistochemical expression of EGFR, p53, p16 and p27. Multivariate analysis was conducted to examine their role in survival.

RESULTS

Many of the markers were highly expressed in these cancers. Membranous EGFR expression in 95.2%, both membrane and cytoplasm expression in 35%, p53 expression in 61.6%, p27 expression in 89.5% and p16 expression in 27.9% of cases. In the multivariate analysis, independent prognostic influence of a lower overall survival was determined only for advanced tumour stage (P < 0.001), p53 overexpression (P = 0.004), EGFR cytoplasm and membrane co-expression location (P = 0.002) and p16 reduced expression (P = 0.002). When considering a subgroup of early stage tumours, p53 overexpression (P = 0.028) and combined membranous and cytoplasm EGFR co-expression (P = 0.039) were indicators of a lower overall survival. For disease-free survival, in addition to these three factors, the histological grade (P = 0.011) showed independent prognostic values.

CONCLUSION

The independent value of EGFR subcellular location (cytoplasm and membrane) and p53 overexpression in overall survival even in early stages of OSCC suggests that these markers may serve as reliable biological markers to identify high-risk subgroups and to guide therapy.

Correlation between Skp2 expression and nodal metastasis in stage I and II oral squamous cell carcinomas

PURPOSE

The aim of this study was to investigate the role of S-phase kinase associated protein (Skp2) in the development of nodal metastasis and to assess its influence on prognosis in stage I and II oral squamous cell carcinomas (OSCCs).

EXPERIMENTAL DESIGN

Seventy-one patients affected by OSCC (stage I-II) were observed in the period ranging from March 2003 to December 2006. The research was performed using immunohistochemical and histopathological analysis.

RESULTS

The overall survival rate was 89.6% at 3 years, 87% at 5 years and 80.7% at 10 years. Patients with vascular or perineural invasion showed no statistically significant survival difference when compared with the ones with no invasion. The tumour depth of invasion did not prove to be related to the metastatic potential. Nine of the seventeen patients with Skp2 positive nuclei (≥20%) developed nodal metastasis. Conversely, only 6 of the 54 patients with a nuclear positivity lower than 20% developed a laterocervical metastasis (P=0.001). When comparing survival curves of Skp≥20% and Skp2<20% OSCCs, no significant P value emerged from the statistical analysis.

CONCLUSIONS

This study is the first to report an important correlation between an Skp2 expression lower than 20% and the capability of the tumour not to develop nodal laterocervical metastases (P=0.001).

Gastric adenocarcinoma and Helicobacter pylori: correlation with p53 mutation and p27 immunoexpression

INTRODUCTION

Helicobacter pylori infection is an established risk factor for gastric cancer development, but the exact underlying mechanism still remains obscure. The inactivation of tumor suppressor genes such as p53 and p27(KIP1) is a hypothesized mechanism, although there is no consensus regarding the influence of H. pylori cagA(+) in the development of these genetic alterations.

GOALS

To verify the relationship among H. pylori infection, p53 mutations and p27(Kip1) Protein (p27) expression in gastric adenocarcinomas (GA) seventy-four tissues were assayed by PCR for H. pylori and cagA presence. Mutational analysis of p53 gene was performed by single-strand conformation polymorphism (SSCP). Seventy tissues were analyzed by an immunohistochemical method for p27 expression.

RESULTS

From the samples examined, 95% (70/74) were H. pylori positive, 63% cagA(+). Altered p53 electrophoretic mobility was found in 72% of cases and significantly more frequent in the presence of cagA. Considerable reduction in p27 expression (19%) was found with a tendency for association between cagA(+) and p27(-), although the results were not statistically significant. Concomitant alterations of both suppressor genes were detected in 60% of cases. In the cases cagA(+), 66.7% of them had these concomitant alterations.

CONCLUSIONS

The data suggest that H. pylori cagA(+) contributes to p53 alteration and indicate that concomitant gene inactivation, with reduced p27 expression, may be a mechanism in which H. pylori can promote the development and progression of gastric cancer.

The enigmatic parietal epithelial cell is finally getting noticed: a review

Although the normal glomerulus comprises four resident cell types, least is known about the parietal epithelial cells (PECs). This comprehensive review addresses the cellular origin of PECs, discusses the normal structure and protein makeup of PECs, describes PEC function, and defines the responses to injury in disease and how these events lead to clinical events. The data show that PECs have unique properties and that new functions are being recognized such as their role in differentiating into podocytes during disease.

Suppression of anoikis by SKP2 amplification and overexpression promotes metastasis of esophageal squamous cell carcinoma

The gene of SKP2, located on chromosome 5p13, plays a critical role in cell cycle progression, especially at the G(1)-S transition, putatively through its control of several cell cycle regulator proteins including p27(kip1), p21(cip1), p57(kip2), p130, cyclin E, and c-Myc. Previous studies in this laboratory revealed that gain of chromosome 5p was often seen in esophageal squamous cell carcinoma (ESCC). In the present study, we examined the amplification status and expression level of SKP2 in ESCC and investigated its clinicopathologic significance. Amplification and elevated expression of SKP2 correlated significantly with tumor stage and positive lymph node metastasis (P < 0.05). The SKP2 protein expression level as determined by immunohistochemical staining showed a significant inverse correlation with p27 protein. In vivo assay showed that inhibition of SKP2 expression also decreased tumor growth and lung metastasis of ESCC cells. At the molecular level, knockdown of SKP2 by RNA interference inhibited cell migration and invasion ability. Knockdown of SKP2 expression sensitized cancer cells to anoikis, and a wobble mutant of SKP2 that is resistant to SKP2 small interfering RNA can rescue this effect. Expression level of pAkt decreased after SKP2 knockdown. Treatment of cells with phosphoinositidyl 3-kinase inhibitor (LY294002) and constitutively activator (insulin-like growth factor I) had significant effects on the anoikis of SKP2 RNA interference cells. These results show for the first time that SKP2 is amplified and overexpressed in ESCC. Elevated expression of SKP2 protected cancer cells from anoikis, and this effect was mediated, at least in part, by the phosphoinositidyl 3-kinase-Akt pathway.

Applications of RNA interference in cancer therapeutics as a powerful tool for suppressing gene expression

Cancer poses a tremendous therapeutic challenge worldwide, highlighting the critical need for developing novel therapeutics. A promising cancer treatment modality is gene therapy, which is a form of molecular medicine designed to introduce into target cells genetic material with therapeutic intent. The history of RNA interference (RNAi) has only a dozen years, however, further studies have revealed that it is a potent method of gene silencing that has developed rapidly over the past few years as a result of its extensive importance in the study of genetics, molecular biology and physiology. RNAi is a natural process by which small interfering RNA (siRNA) duplex directs sequence specific post-transcriptional silencing of homologous genes by binding to its complementary mRNA and triggering its elimination. RNAi has been extensively used as a novel and effective gene silencing tool for the fundamental research of cancer therapeutics, and has displayed great potential in clinical treatment.

Establishment and characterization of a tumorigenic cell line from areca quid and tobacco smoke-associated buccal carcinoma

A cell line, TW2.6, has been established from the surgically resected specimen of an untreated primary squamous cell carcinoma of the buccal mucosa from a 48-year-old man who was an areca quid chewer and tobacco smoker. TW2.6 cells exhibited morphological features of keratinocytes and replicated rapidly in culture with a doubling time of 24h. The karyotype showed human chromosomes with high hyperdiploidy and complex rearrangements. Western blotting showed pronounced expression of p53 and moderate expression of p21(CIP1). The baseline expressions of p27(KIP1) and p16(INK4a) were barely detectable. Low levels of Bax and Fas were found in TW2.6 cells but Bcl-2 expression was more readily observed. Mutational analysis of p53 gene revealed an A-->G transition at the second base of codon 220, resulting in amino acid substitution from tyrosine to cysteine in the protein. Functional analysis showed that TW2.6 was unable to activate the p53-specific PUMA promoter. Lipofectamine 2000 and calcium phosphate precipitation technique offer good transfection efficiencies for TW2.6 cells and may be used in future transfection experiments. A xenograft-SCID mouse tumor model was established for TW2.6. Histological examination demonstrated that the engrafted tumors maintained the morphological features of a squamous cell carcinoma. It is thought that the establishment of tumorigenic TW2.6 cell line provides a valuable model for AQ and tobacco smoke-associated buccal carcinoma.

Molecular markers of head and neck squamous cell carcinoma: promising signs in need of prospective evaluation

BACKGROUND

The aim of this article is to review recent developments in the biological understanding of head and neck squamous cell carcinomas.

METHODS AND RESULTS

We describe the markers according to their function and their prognostic or predictive roles. Some associations can be found between molecular markers and invasiveness, aggressiveness, degree of differentiation, and tumor stage, but only a few clinical studies have shown an impact on prognosis. In addition, despite an increasing number of articles relating to this topic, the small number of patients included in the studies reported reduces the clinical implications of these results. Few studies applied a more comprehensive molecular analysis approach, such as DNA microarrays or differential expression profiling by polymerase chain reaction, to identify a combination of markers that could be more informative than a single molecular marker.

CONCLUSION

Some progress has been made with respect to molecular markers and head and neck cancers. Translational and prospective, hypothesis-driven research must proceed with sufficient rigor to facilitate the clinical applicability of such results.

Knockdown of Skp2 by siRNA inhibits melanoma cell growth in vitro and in vivo

BACKGROUND

Low levels of p27Kip1 expression are associated with poor prognosis in various malignancies including malignant melanoma. Recently, it has been reported that S phase kinase-interacting protein 2 (Skp2), the specific ubiquitin ligase subunit that targets p27Kip1 for degradation, was overexpressed and was inversely related to p27Kip1 levels in malignant melanoma with poor prognosis.

OBJECTIVE

We investigated whether small interfering RNA (siRNA)-mediated gene silencing of Skp2 can be employed in order to inhibit p27Kip1 down-regulation and suppress melanoma cell growth as a consequence in vitro and in vivo.

METHODS

We constructed a plasmid vector, which synthesizes siRNAs to determine the effects of decreasing the high constitutive levels of Skp2 protein in melanoma cells. Western blot and real-time RT-PCR were performed to examine the decreases of Skp2 protein and mRNA in vitro. Furthermore, melanoma cells were injected into the back of nude mice subcutaneously to examine the suppression of tumorigenicity targeting Skp2 gene silencing in vivo.

RESULTS

Skp2 protein was decreased and the p27Kip1 protein was accumulated in Skp2 siRNA transfected melanoma cells. Skp2 siRNA inhibited the cell growth of melanoma cells in vitro. Moreover, Skp2 siRNA also suppressed tumor proliferation in vivo.

CONCLUSION

Our results suggest that siRNA-mediated gene silencing of Skp2 can be a potent tool of cancer gene therapy for suppression of p27Kip1 degradation in malignant melanoma.

Down-regulation of Cdk inhibitor p27 in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most frequent malignant neoplasm of the head and neck region. Conversion of normal cells to cancer cells is achieved through a multi-step process that is closely associated with the accumulation of multiple gene changes including both oncogenes and tumour suppressor genes. The proliferation and progression of cancer may be caused by abnormalities of various positive and negative cell cycle regulators. Cell cycle progression is positively regulated by multiple cyclins and cyclin-dependent kinases (Cdks) and cyclin/Cdk complexes are negatively regulated by a number of Cdk inhibitors including p27. p27 is a Cdk inhibitor and plays an important role in negative regulation of the cell cycle during G0 and G1 phases. Degradation of p27 is a critical event for the G1/S transition and occurs through ubiquitination by SCF(Skp2) and subsequent degradation by the 26S proteasome. It has been revealed that down-regulation of p27 is frequently found in various cancers, including OSCC, and is due to an enhancement of its degradation. Importantly, down-regulation of p27 is well associated with its malignancy including poor prognosis in various cancers. Moreover, aggressive human cancers express low levels of p27 because of its decreased stability. More recent evidence suggests that Skp2 and Cks1, the specific recognition factors for p27 ubiquitination, have oncogenic properties. This review will focus on down-regulation of p27 and mechanism of its down-regulation in OSCC.

Small interfering RNA targeting of S phase kinase–interacting protein 2 inhibits cell growth of oral cancer cells by inhibiting p27 degradation

S phase kinase-interacting protein 2 (Skp2), an F box protein, is required for the ubiquitination and consequent degradation of p27. It is well known that reduced expression of p27 is frequently observed in various cancers including oral squamous cell carcinoma and is due to an enhancement of its protein degradation. Our previous study showed that overexpression of Skp2 was frequently found in oral squamous cell carcinoma and inversely correlated with p27 expression. Recently, a technique known as RNA interference has been successfully adapted to mammalian cells. In the present study, we investigated if small interfering RNA (siRNA)-mediated gene silencing of Skp2 can be employed in order to inhibit p27 down-regulation in oral squamous cell carcinoma. We used a siRNA plasmid vector, which has an advantage over synthetic siRNAs in determining the effects of decreasing the high constitutive levels of Skp2 protein in oral squamous cell carcinoma. We showed that Skp2 siRNA transfection decreased Skp2 protein and induced the accumulation of p27 protein in oral squamous cell carcinoma cells. Moreover, p27 protein in Skp2 siRNA-transfected cells is more stabilized than that in control siRNA-transfected cells. Interestingly, Skp2 siRNA inhibited the cell proliferation of oral squamous cell carcinoma cells both in vitro and in vivo. Our findings suggest that siRNA-mediated gene silencing of Skp2 can be a novel modality of cancer gene therapy for suppression of p27 down-regulation.

Overexpression of cyclin D1 and interaction between p27Kip1 and tumour thickness predict lymph node metastases occurrence in lower lip squamous cell carcinoma

We have attempted to identify those subgroups of patients most likely to develop lymph node metastases from squamous cell carcinoma of the lower lip (LLSSC). A total of 97 subjects, who did not undergo elective neck dissection, were recruited into the 60-month disease-free survival study. After univariate analysis, tumour size, histological grading, maximal thickness, perineural invasion and immunoreactivity to cyclin D1 and p27Kip1 proteins proved to be significant factors. Tests of the effect of interaction between p27Kip1 LI and tumour thickness yielded that the impact of tumour thickness on the risk of lymph node metastases was modified by the percentage of p27Kip1 positive cells. Subsequent to models of multivariate analysis, tumour size, positive cyclin D1 protein expression, maximal thickness (> 5 mm), p27Kip1 LI (%) and the interaction term between p27Kip1 LI and tumour thickness retained strong independent predictive values for lymph node metastases. We suggest that immunohistochemistry for cyclin D1 and p27Kip1 may prove to be valuable ancillary tests for identifying LLSSC with metastatic potential.

Role of Cks1 overexpression in oral squamous cell carcinomas: cooperation with Skp2 in promoting p27 degradation

Down-regulation of p27 is frequently observed in various cancers due to an enhancement of its degradation. Skp2 is required for the ubiquitination and consequent degradation of p27 protein. Another protein called Cks1 is also required for p27 ubiquitination in the SCF(Skp2) ubiquitinating machinery. In the present study, we examined Cks1 expression and its correlation with p27 in oral squamous cell carcinoma (OSCC) derived from tongue and gingiva. By immunohistochemical analysis, high expression of Cks1 was present in 62% of OSCCs in comparison with 0% of normal mucosae. In addition, 65% of samples with low p27 expression displayed high Cks1 levels. Finally, Cks1 expression was well correlated with Skp2 expression and poor prognosis. To study the role of Cks1 overexpression in p27 down-regulation, we transfected Cks1 with or without Skp2 into OSCC cells. Cks1 transfection could not induce a p27 down-regulation by itself, but both Cks1 and Skp2 transfection strongly induced. Moreover, we inhibited Cks1 expression by small interference RNA (siRNA) in OSCC. Cks1 siRNA transfection induced p27 accumulation and inhibited the growth of OSCC cells. These findings suggest that Cks1 overexpression may play an important role for OSCC development through Skp2-mediated p27 degradation, and that Cks1 siRNA can be a novel modality of gene therapy.

Association between the V109G Polymorphism of the p27 Gene and the Risk and Progression of Oral Squamous Cell Carcinoma

PURPOSE

Abnormalities in p27 may alter cell cycle delay required for DNA repair after exposure to carcinogens. A coding exon 1 polymorphism at codon 109 (T-->G) in p27 was identified and thought to have an effect on the functions of its protein. We hypothesized that this p27 T109G polymorphism is associated with squamous cell carcinoma of the head and neck (SCCHN) risk.

EXPERIMENTAL DESIGN

We tested this hypothesis in a hospital-based case-control study of 713 patients newly diagnosed with SCCHN and 1224 cancer-free controls frequency matched to the cases by age (+/-5 years), sex, and smoking status. All subjects were non-Hispanic whites. We genotyped for this p27 variant using genomic DNA from each subject.

RESULTS

Compared with the p27 109VV variant, the p27 109GG variant was associated with a nonsignificantly increased risk of SCCHN [crude odds ratio (OR) = 1.29; 95% confidence interval (CI) = 0.88-1.90; adjusted OR = 1.20; 95% CI = 0.81-1.77], but the risk was statistically significant among men (adjusted OR = 1.55, 95% CI = 1.00-2.42), current alcohol users (adjusted OR = 1.68, 95% CI = 1.01-2.82), and patients with oral cavity cancer (adjusted OR = 1.77, 95% CI = 1.03-3.04). The p27 109GG variant was also associated with oral tumor overall stage, suggesting that it may play a role in tumor progression.

CONCLUSIONS

Our findings suggest that the p27 109GG variant genotype may not play a major role in the etiology of SCCHN but may be associated with an increased risk in at-risk subgroups or subsets of SCCHN, particularly oral cavity cancer and possibly tumor progression. Larger studies with oral squamous cell carcinoma are needed to verify these findings.

Lymph node metastasis in lower lip squamous cell carcinoma in relation to tumour size, histologic variables and p27Kip1 protein expression

We studied a consecutive series of 95 patients undergoing radical surgical resection of lower lip squamous cell carcinoma (LLSCC) to assess the correlation between lymph node status and several prognostic variables, such as sex and age, tumour size, histologic grading, maximal microscopic tumour thickness, perineural infiltration and p27Kip1 protein status, to see which of these might be predictive of the development of lymph node metastases. Statistical analysis demonstrated a significant association between node status and tumour size, histological grading, maximal thickness, perineural invasion and p27Kip1 protein expression; additionally to node metastasis, low p27Kip1 protein expression was significant correlated with high microscopic thickness. These results indicate that lower lip squamous cell carcinomas of >2 cm, with G3-G4 histological grading, maximal thickness of >6 mm, perineural invasion and low p27Kip1 protein expression (LI<19.7%) are at high risk for the development of lymph node metastases.

Human papillomavirus positivity predicts favourable outcome for squamous carcinoma of the tonsil

Mutations in the p53 and retinoblastoma (pRb) pathways associated with the use of tobacco and alcohol are common in squamous cell carcinoma (SCC) of the head and neck. Cell cycle proteins are also affected by human papillomavirus (HPV), which may also have an aetiological role in cancers at particular sites, most notably the tonsil. Attempts to identify prognostic molecular markers in head and neck cancers have met with conflicting results, but few studies have been undertaken with tumours of known HPV status at a single anatomic site. In our study 86 tonsil cancers were analysed for HPV status by sequence analysis of polymerase chain reaction products and for the expression of cell cycle proteins (p53, p21(CIP1/WAF1), pRb, p16(INK4A), cyclin D1 and p27(KIP1)) by immunohistochemistry. The HPV status could be established in 67 of the tumours. Thirty-one (46%) of these were HPV-positive, predominantly (28/31) for HPV16. Findings were related to tumour recurrence and patient survival. None of the cell cycle proteins independently predicted recurrence or survival. Patients with HPV-positive tumours, however, were significantly less likely (p < 0.05) to have recurrence or to die of disease than those with HPV-negative tumours, after adjusting for the effects of the cell cycle proteins, clinical stage, pathological node status, tumour grade, age, gender and treatment. These findings support the concept that HPV-positive tonsil cancers may be a distinct biological group with less aggressive characteristics. Screening of tonsil cancers for HPV DNA may help optimise treatment and provide more accurate prognostic information.

Establishment of an oral squamous cell carcinoma cell line with high invasive and p27 degradation activities from a lymph node metastasis

The extent of lymph node metastasis is a major determinant in the prognosis of oral squamous cell carcinoma (OSCC). We present here a new OSCC cell line, MSCC-1, established from a lymph node metastasis of a patient with OSCC of gingiva. First, we examined the expression of p27, p53 and Ki-67 in non-neoplastic mucosa, primary and metastatic cancer lesions by immunohistochemistry. Metastatic cancer cells in the lymph node showed the reduced expression of p27 in comparison with cancer cells in the primary lesion. Cancer celLs both in the primary and metastatic lesions showed overexpression of p53 and Ki-67. Overexpression of p53 and reduced expression of p27 in MSCC-1 cells were also determined by western blot analysis. To characterize MSCC-1 cells, furthermore, we examined the invasive activity and cell proliferation of MSCC-1, comparing with those of other OSCC cell lines, HSC-2 and HSC-3 cells. The invasive capacity of MSCC-1 cells was significant higher than HSC-2 and HSC-3 cells, but cell growth of MSCC-1 cells was slower than HSC-2 and HSC-3 cells. Moreover, we examined the p27 degradation activity by in vitro degradation assay. Interestingly, MSCC-1 cells have the strongest p27 degradation activity among the OSCC cell lines examined. In the present study, we newly established MSCC-1 cells with strong invasiveness and p27 degradation activity from a metastatic lesion. These findings suggest that high activity of p27 degradation may concern with invasiveness of OSCC cells and that MSCC-1 cells can be a useful cell model for studying the detailed mechanism of p27 degradation, invasion and metastasis of OSCC.

Reduced expression of p27 is correlated with progression in precancerous lesions of the larynx

OBJECTIVES

Factors related to malignant transformation of laryngeal precancerous lesions remain largely unknown, so we investigated the relationship between the expression of p27 and precancerous laryngeal lesion.

STUDY DESIGN

In this study we investigated the expressions of p27 and p53 protein in 56 cases with laryngeal precancerous or cancer lesions (20 cases of hyperplasia, 19 of dysplasia, and 17 of squamous cell carcinoma), and went on to evaluate the relationship between immunoreactivity of each of them and the histological findings. We also evaluated the correlation between immunoreactivity and proliferative activity with the aid of Ki-67 nuclear antigen staining.

METHODS

A retrospective study was performed in 56 cases (20 with epithelial hyperplasia, 19 with epithelial dysplasia and 17 with laryngeal cancer). Immunohistochemistry was performed to investigate expression of p27, p53 protein and Ki-67 nuclear antigen staining, using the avidian-biotin-peroxidase complex technique.

RESULTS

p27 immunostaining was observed in 12 out of 20 cases of hyperplasia (60%), six out of 19 cases of dysplasia (31%), and 2/17 (12%) of carcinoma. We found significant association between p27 immunostaining and the histological findings. On the other hand, p53 immunostaining was observed in 6/20 (30%) of hyperplasia, 3/19 (16%) of dysplasia, and 7/17 (41%) of carcinoma. No significant association was found between p53 and the histological findings.

CONCLUSIONS

Our results revealed that immunohistochemical assessment of p27 in bioptic samples of laryngeal precancerous lesions might be useful in selective patients who should undergo a more specific follow-up evaluation.

Transfection of p27(Kip1) threonine residue 187 mutant type gene, which is not influenced by ubiquitin-mediated degradation, induces cell cycle arrest in oral squamous cell carcinoma cells

OBJECTIVE

It is well known that reduction of the cyclin-dependent kinase inhibitor p27(Kip1) protein correlates with the malignant behavior of various cancers including oral squamous cell carcinoma (OSCC). The loss of p27(Kip1) protein is suggested to be due to the enhancement of its posttranslational degradation. In the present study, to evaluate the effects of p27(Kip1) transfection on the cell cycle, we transfected OSCC cell lines with a high activity of p27(Kip1) degradation with p27(Kip1) threonine 187-to-alanine (T187A) mutant gene, which is not influenced by ubiquitin-mediated degradation, as well as with wild type gene.

METHODS

We transfected p27(Kip1) T187A mutant and wild type gene into OSCC cell lines (HSC2 and HSC3) by using an ecdysone-inducible gene expression system.

RESULTS

After treatment with ponasterone A, we could find an induction of both p27(Kip1) wild type and T187A mutant protein. Both wild type and T187A mutant protein induced by 5 microM ponasterone A inhibited cell growth and increased cell number at the G1 phase. After treatment with 1 microM ponasterone A, ectopic p27(Kip1) protein was degraded in wild type clones, but not in T187A mutant clones. Moreover, transfection of the T187A mutant gene was more effective in inhibiting cell growth even by induction of a small amount of protein.

CONCLUSION

We suggest that the transfection of the p27(Kip1) T187A mutant gene can be a modality of cancer gene therapy for OSCC.

Expression of p27(Kip1) in bladder cancers: immunohistochemical study and prognostic value in a series of 95 cases

Prognostic value of p27(Kip1) immunohistochemical expression was evaluated in a series of 95 bladder carcinomas. Low p27(Kip1) expression was correlated with higher tumor grade (P=0.01) and stage (P=0.009), associated with poor overall survival (P=0.01) and, for superficial cancers, with disease-free survival (P=0.05). Thirty-five cases exhibited a heterogeneous expression related in some instances to tumoral architecture. Seventeen cases showed a cytoplasmic reactivity related to low nuclear expression (P=0.057). Loss of p27(Kip1) expression is a pejorative event in bladder tumors and inhibition of p27(Kip1) degradation could offer new therapeutic ways.

Overexpression of p27(Kip1) induces growth arrest and apoptosis in an oral cancer cell line

p27(Kip1) is a cyclin-dependent kinase inhibitor which regulates progression of cells from G1 into S phase in a cell cycle. Loss of p27(Kip1) has been associated with disease progression and an unfavorable outcome in several malignancies. In the present study, we conducted to examine whether up-regulation or down-regulation of p27(KiP1) can affect the growth of oral cancer cell (B88 cell) in vitro and in vivo. We constructed an expression vector containing sense- or antisense-oriented human p27(Kip1) cDNA with pcDNA3.1(Invitrogen). We transfected B88 cells with the sense or antisense expression vector to regulate the expression of p27(Kip1) gene in each transfectant. The expression of p27(Kip1) protein was up-regulated in the sense transfectants and down-regulated in the antisense transfectants. Moreover, up-regulation of p27(Kip1) protein exerted the growth inhibitory effect, and down-regulation of p27(Kip1) protein enhanced the growth of B88 cells in vitro and in vivo. Furthermore, we detected the G1 arrest and sub-G1 peak in the sense transfectants by flow cytometry analysis. These results suggest that up-regulation of p27(Kip1) protein may exert the growth inhibitory effects through induction of G1 arrest and apoptosis on oral cancer cell line.

Prognostic role of p27(Kip1) expression in oral squamous cell carcinoma in Taiwan

The cyclin-dependent kinase inhibitor p27(Kip1) can inhibit the G1 to S transition of the cell cycle and is a putative tumor suppressor. Decreased expression of p27(Kip1) protein has been correlated with poor prognosis in a variety of human tumors. We examined the expression of p27(Kip1) in oral squamous cell carcinoma (SCC), epithelial dysplasia (ED) and normal oral mucosa (NOM) using antibodies to p27(Kip1). Positive p27(Kip1) nuclear staining was detected in all the specimems from ED and NOM, whereas positive p27(Kip1) staining was observed in 16 of the 63 (25%) cases of oral SCC. The labeling index for p27(Kip1) protein was significantly reduced from NOM through ED to oral SCCs, indicating that changes of p27(Kip1) protein expression may be an early event in oral carcinogenesis in Taiwan. The Kaplan-Meier analysis showed patients with p27(Kip1)-positive tumors had significantly higher overall survival than those with p27(Kip1)-negative tumors in a total of 63 patients (P=0.015) and 47 patients with areca quid chewing habit (P=0.026). Multivariate analysis showed decreased p27(Kip1) protein expression was an independent significant predictor of poor overall survival in the patients with oral SCCs. These results indicate that p27(Kip1) protein expression may serve as a putative new adjuvant prognostic marker for routine assessment of oral SCC patients.

Genetic aberrations in oral or head and neck squamous cell carcinoma 3: clinico-pathological applications

The molecular changes in malignant epithelium in the head and neck offer possibilities for the development of diagnostic, prognostic and other markers. This article reviews recent developments in this field.

Squamous carcinoma of the head and neck: molecular mechanisms and potential biomarkers

Squamous cell carcinoma (SCC) of the head and neck remains a major health problem worldwide. Recent advances in cell biology suggest that cancer results from the accumulation of specific genetic mutations, many of which have now been identified. These mutations can cause the activation of genes that promote cellular proliferation or inhibit cell death (oncogenes), or they may inactivate genes that inhibit proliferation or promote cell death (tumour suppressor genes). Although there is no known set sequence of events leading to the formation of SCC of the head and neck, there is evidence that many of the genomic mutations implicated in other forms of cancer have an aetiological role in these tumours. Certain viruses, notably Epstein-Barr virus and some types of human papillomaviruses, are causally related to some head and neck cancers. There is now the prospect of using molecular markers to achieve earlier diagnosis and to aid in the prediction of both tumour behaviour and likely responses to particular treatment modalities.

Reduced expression of p27(Kip1) correlates with an early stage of cancer invasion in oral squamous cell carcinoma

Down-regulation of p27(Kip1) has been reported to correlate with poor survival of various carcinoma patients including oral squamous cell carcinomas (OSCCs). It is still unclear, however, at what stage of oral carcinogenesis the down-regulation of this protein occurs. In this study, therefore, we evaluated immunoexpression of p27(Kip1) protein in 17 cases of oral epithelial dysplasia and succeeding invasive OSCC in the same patient. We reported here that 88% cases showed high p27(Kip1) expression in dysplastic lesions, whereas 82% cases of succeeding invasive OSCC exhibited reduced expression. The reduction of p27(Kip1) expression was also observed in 16 of 19 (84%) early invasive lesions and well correlated with Ki-67 expression which is good indicator of cell proliferation. We also investigated immunoexpression of p53 protein of which abnormality has been known to occur during the early stage of OSCC development. Overexpression of p53 protein was demonstrated in 29% of dysplastic lesions, 42% of early invasive and 71% of invasive OSCCs. These findings suggest that abnormalities of both p53 and p27(Kip1) are involved in the carcinogenesis of OSCC, but they seem to play their role at different stages of oral cancer development, respectively. Reduced expression of p27(Kip1) may concern the cancer invasion directly or indirectly as well as abnormal proliferation.

Cyclin-dependent kinase inhibitor p27(Kip1) expression in transitional cell carcinoma of renal pelvis and ureter

We examined the expression and significance of p27(Kip1) protein in 79 patients with transitional cell carcinoma of the renal pelvis and ureter. Immunohistochemical staining of archival tissue specimens was done using a labeled streptavidin-biotin-peroxidase method. There was no significant association between p27(Kip1) labeling index and histologic grade or pathologic stage. Patients with p27(Kip1) labeling indices of 27 or greater had more favorable prognoses in comparison to those with p27(kip1) labeling indices less than 27 (P<0.01). Multivariate analysis indicated that p27(Kip1) had an independent predictive prognostic value (P<0.05). The p27(Kip1) may be a novel prognostic marker for transitional cell carcinoma of the renal pelvis and ureter.