p16INK4A as a marker for cervical dyskaryosis: CIN and cGIN in cervical biopsies and ThinPrep smears

AIM: To examine the potential of p16(INK4A) as a biomarker for dysplastic squamous and glandular cells of the cervix in tissue sections and ThinPrep smears. METHODS: Immunocytochemical analysis of p16(INK4A) expression was performed on 22 normal cervical tissue samples, five cervical glandular intraepithelial neoplasia (cGIN), 38 cervical intraepithelial neoplasia 1 (CIN1), 33 CIN2, 46 CIN3, and 10 invasive cancer cases (eight squamous and two adenocarcinomas). All samples were formalin fixed and paraffin wax embedded, and immunohistochemical analysis was carried out using a mouse monoclonal anti-p16(INK4A) antibody after antigen unmasking. The staining intensity was assessed using a 0 to 3 scoring system. In addition, the expression status of p16(INK4A) was examined in 12 normal ThinPrep smears, one smear exhibiting cGIN, and a total of 20 smears exhibiting mild, moderate, and severe dyskaryosis. Human papillomavirus (HPV) detection was carried out using a modified SYBR green assay system. Fluorogenic polymerase chain reaction (PCR) and solution phase PCR were used for specific HPV typing. RESULTS: p16(INK4A) immunoreactivity was absent in all normal cervical tissues examined. Dysplastic squamous and glandular cells were positive for p16(INK4A) expression in all cases included in this study, except for one CIN3 case. p16(INK4A) expression was mainly nuclear in CIN1 cases, and both nuclear and cytoplasmic in CIN2, CIN3, cGIN, and invasive cases. All cases positive for HPV expressed the p16(INK4A) protein, although not all cases found positive for p16(INK4A) were HPV positive. In general, the p16(INK4A) staining intensity was lower in cases negative for HPV or those containing a low risk HPV type. CONCLUSION: This pattern of overexpression demonstrates the potential use of p16(INK4A) as a diagnostic marker for cervical squamous and also glandular neoplastic lesions. In addition, the technique can be used to identify individual dyskaryotic cells in ThinPrep smears. Thus, p16(INK4A) is a useful marker of cervical dyskaryosis.     

Estimation of prognoses for cervical intraepithelial neoplasia 2 by p16INK4a immunoexpression and high-risk HPV in situ hybridization signal types

The present study used immunohistochemical staining and in situ hybridization (ISH) to examine whether progression of cervical intraepithelial neoplasia, grade 2 (CIN 2) can be predicted by p16INK4a immunoexpression and high-risk human papilloma virus (HPV) ISH signal types. We studied 52 cases histologically diagnosed with CIN 2: dysplasia regressed in 28 cases; 13 cases progressed to CIN 3; and CIN 2 persisted in 11 cases. Expression of p16INK4a and high-risk HPV signal both related to grade of CIN. Stronger p16INK4a immunoexpression and a higher frequency of expression of a punctate nuclear signal were observed in CIN 2 lesions before progression compared with those before regression. CIN 2 cases in which moderate to strong immunoexpression of p16INK4a and a punctate signal were observed simultaneously progressed to CIN 3 in 10 (91%) of 11 cases. CIN 2 cases with moderate to strong immunoexpression of p16INK4a and a high-risk HPV punctate signal should be treated because of the great risk of progression.     

p16INK4A, CDC6, and MCM5: predictive biomarkers in cervical preinvasive neoplasia and cervical cancer

AIM: To analyse and compare expression patterns of three potential biomarkers-p16(INK4A), CDC6, and MCM5-and evaluate their use as predictive biomarkers in squamous and glandular cervical preinvasive neoplasia. METHODS: Immunocytochemical analysis of p16(INK4A), MCM5, and CDC6 expression was performed on 20 normal, 38 cervical intraepithelial neoplasia 1 (CIN1), 33 CIN2, 46 CIN3, 10 squamous cell carcinoma, 19 cervical glandular intraepithelial neoplasia (cGIN), and 10 adenocarcinoma samples. Staining intensity was assessed using a 0-3 scoring system. p16(INK4A), MCM5, and CDC6 expression was also examined in ThinPrep slides exhibiting mild, moderate, and severe dyskaryosis. Human papillomavirus (HPV) was detected using a modified SYBR green assay. Fluorogenic polymerase chain reaction (PCR) and solution phase PCR were used for specific HPV typing. RESULTS: All three markers showed a linear correlation between expression and grade of dysplasia. p16(INK4A) and MCM5 protein expression was upregulated in all grades of squamous and glandular dysplasia. CDC6 protein was preferentially expressed in high grade lesions and in invasive squamous cell carcinoma. CONCLUSION: p16(INK4A) expression was closely associated with high risk HPV infection-all grades of squamous and glandular cervical lesions were immunohistochemically positive. MCM5 staining intensity was independent of high risk HPV infection, highlighting its potential as a biomarker in both HPV dependent and independent cervical dysplasia. CDC6 may be a biomarker of high grade and invasive lesions of the cervix, with limited use in low grade dysplasia. p16(INK4A) was the most reliable marker of cervical dysplasia. Combinations of dysplastic biomarkers may be useful in difficult diagnostic cases.     

Human papillomavirus genotyping and p16INK4a expression in cervical intraepithelial neoplasia of adolescents.

Adolescents have high rates of human papillomavirus (HPV) infection, and persistent high-risk HPV infection can lead to the development of cervical cancer. The cyclin-dependent kinase inhibitor, p16(INK4a) is overexpressed in cervical intraepithelial neoplasia (CIN), probably due to a persistent and integrated HPV infection. This study investigated p16(INK4a) expression, grades of CIN, and high-risk HPV infection in adolescent cervical biopsies. Biopsies were immunohistochemically stained for p16(INK4a). The presence of wide-spectrum, low-risk, or high-risk HPV was determined by amplifying DNA extracted from the cervical biopsies. Biopsies were classified as cervicitis, 15 cases; CIN 1, 48 cases; CIN 2, 46 cases, and CIN 3, 52 cases. The distribution of p16(INK4a) staining was graded as patchy, diffuse basal, and diffuse full thickness. Pearson's chi(2) tests analyzed the relationships between p16(INK4a) staining, HPV infection, and CIN. Biopsies of cervicitis were negative for HPV and for p16(INK4a) expression. High-risk HPV 16, 18, and 31 increased from 18% in CIN 1 to 66% in CIN 2/3 (P<0.001). In CIN 1, p16(INK4a) was positive in 44% of biopsies with 35% showing patchy, 7% diffuse basal, and one case (2%) showing diffuse full thickness staining. In CIN 2/3, p16(INK4a) was positive in 97% of biopsies with 23% showing patchy, 21% diffuse basal, and 53% diffuse full thickness staining. The difference in the proportions of biopsies showing patchy p16(INK4a) staining in CIN 1 and diffuse full thickness staining in CIN 2/3 was significant (P<0.001). In CIN 1, 61% of high-risk HPV-positive biopsies were p16(INK4a) negative, while all high-risk HPV-positive CIN 2/3 biopsies were p16(INK4a) positive. Diffuse, full thickness p16(INK4a) expression discriminated low-grade from high-grade CIN and appears to be a marker of persistent high-risk HPV infection.     

P16<Superscript>INK4a</Superscript> expression and progression risk of low-grade intraepithelial neoplasia of the cervix uteri

The aim of the study was to evaluate the immunohistochemical expression of p16^INK4a as a marker of progression risk in low-grade dysplastic lesions of the cervix uteri. p16^INK4a immunohistochemistry was performed on 32 CIN1 with proven spontaneous regression of the lesion in the follow-up (group A), 31 (group B) with progression to CIN3 and 33 (group C) that were randomly chosen irrespective of the natural history of the lesion. p16^INK4a staining pattern was scored as negative (less than 5% cells in the lower third of dysplastic epithelium stained), as focally positive (25%) and as diffuse positive (>25%). A diffuse staining pattern was detected in 43.8% of CIN1 of group A, 74.2% of group B and 56.3% of group C. No p16^INK4a staining was detected in 31.3% and 12.9% CIN1 lesions of groups A and B, respectively. Overall, 71.4% and 37.8% of p16^INK4a-negative and diffusely positive CIN1 had regressed at follow-up, whereas 28.6% and 62.2% negative and diffusely positive CIN1 were progressed to CIN3, respectively (P<0.05). All CIN3 lesions analyzed during follow-up of group B were diffusely stained for p16^INK4a. Although p16^INK4a may be expressed in low-grade squamous lesions that undergo spontaneous regression, in this study, CIN1 cases with diffuse p16^INK4a staining had a significantly higher tendency to progress to a high-grade lesion than p16^INK4a-negative cases. p16^INK4a may have the potential to support the interpretation of low-grade dysplastic lesions of the cervix uteri.     

An analysis on the combination expression of HPV L1 capsid protein and p16INK4a in cervical lesions

Human papillomavirus (HPV) infection in cervix is the most important reason for cervical cancer, but only 2% cervical HPV infection will develop into cervical cancer. So how to identify patients at risk of progressive cervical lesions from those infected with HPV to avoid over treatment is a big issue in clinic. The aims of this study were to detect the expression of HPV L1 capsid protein and p16^INK4a in cervical lesions and to investigate the combination expression of HPV L1 capsid protein and p16^INK4a in cervical lesions and its diagnostic efficiency in clinic. Immunochemical method was used to detect the expression of HPV L1 capsid protein and p16^INK4a in 169 cases of abnormal cytology. Histopathologic test was performed to identify cervical lesions of all the cases. χ² test and spearman's rank correlation were used for statistical analysis. The diagnostic sensitivity, specificity, positive predictive values (PPV), negative predictive values (NPV), accuracy, and the area under the receive operating characteristic (ROC) curve (denoted by A_Z) were calculated with SPSS 13.0. All the statistical tests were two sided at the 5% level of significance. L1 expression decreased (P < 0.001), but p16^INK4a expression increased (P < 0.001) with histopathologic diagnosis increasing. The expression rates of HPV L1 capsid protein, p16^INK4a, and L1(?)/p16(+) in cervical intraepithelial neoplasia (CIN)2, CIN3, and squamous‐cell carcinoma were statistically different from those in CIN1 (P < 0.001). The expressions of HPV L1 capsid protein, L1(+)/p16(+), L1(+)/p16(?), and L1(?)/p16(?) were negatively correlated with the severity of cervical lesions (P < 0.001), whereas the expressions of p16^INK4a and L1(?)/p16(+) were positively correlated with the severity of cervical lesions (P < 0.001). The specificity and A_Z of combining L1 with p16 ^INK4a were statistically higher than L1 or p16 ^INK4a alone (P < 0.05). L1 and p16^INK4a are useful biomarkers for the early diagnosis of cervical lesions. The combination of L1 and p16^INK4a has a higher diagnostic accuracy than L1 or p16^INK4a alone in diagnosis of cervical lesions. Diagn. Cytopathol. 2010;38:573–578. © 2009 Wiley‐Liss, Inc.     

Comparative study of the expression of cellular cycle proteins in cervical intraepithelial lesions

Interaction of human papilloma virus oncoproteins E6 and E7 with cell cycle proteins leads to disturbances of the cell cycle mechanism and subsequent alteration in the expression of some proteins, such as p16^INK4a, cyclin D1, p53 and KI67. In this study, we compared alterations in the expression of these proteins during several stages of intra-epitelial cervical carcinogenesis. Accordingly, an immunohistochemical study was performed on 50 cervical biopsies, including negative cases and intraepithelial neoplasias. The expression patterns of these markers were correlated with the histopathological diagnosis and infection with HPV. The p16^INK4a, followed by Ki67, showed better correlation with cancer progression than p53 and cyclin D1, which recommends their use in the evaluation of cervical carcinogenesis. These monoclonal antibodies can be applied to cervical biopsy specimens to identify lesions transformed by oncogenic HPV, separating CIN 1 (p16^INK4a positive) and identifying high-grade lesions by an increase in the cellular proliferation index (Ki67). In this way, we propose immunomarkers that can be applied in clinical practice to separate patients who need a conservative therapeutic approach from those who require a more aggressive treatment.     

Methylation of p16INK4a is a non-rare event in cervical intraepithelial neoplasia.

The cell cycle inhibitor, p16INK4a may be a useful surrogate biomarker of cervical intraepithelial neoplasia (CIN); however, there is currently no consensus of p16INK4a genetic alterations throughout the multiple step process of CIN. Our goal was to identify the methylation frequency of p16INK4a in each step of CIN that is associated with human papillomavirus (HPV) infection, using several different detection methods of p16INK4a methylation to correlate the data. The present study included a total of 43 patients, including 38 with CIN, and 5 normal patients. Three different methods were used to detect hypermethylation of CpG islands, methylation-specific PCR (MSP) amplification of different primer sets of M1, M2, and M3, pyrosequencing of each forward primer region, and immunohistochemistry of p16INK4a. Analysis of MSP showed that 20 of the 38 CIN patients (52.6%) revealed hypermethylation in at least 1 primer set of the p16INK4a promoter. A complete loss of p16INK4a protein expression was observed in 11 cases (28.9%). There was no observed association of methylation of the p16INK4a gene with either CIN grading (P=0.0698) or HPV status (P=0.2811): specifically 42.9% (3/7) was found in CIN 1, 57.1% (8/14) in CIN 2, and 52.9% (9/17) in CIN 3. In concordance with immunohistochemistry results, hypermethylation of the p16INK4a promoter was significantly correlated with a lack of p16 protein expression (P=0.0145). All positive peaks from pyrosequencing matched the MSP results, which ranged from 6.3% to 24.5%. In conclusion, p16INK4a gene silencing during CIN was not determined to be a particularly rare event; however, it does not correlate with either HPV status or CIN grading.     

Evaluation of p16INK4a and pRb expression in cervical squamous and glandular neoplasia

p16(INK4a) is known to play a critical role as a negative regulator of cell cycle progression and differentiation by controlling the activity of the tumor-suppressor protein pRb. The present study evaluated the expression of p16(INK4a) and pRb in cervical squamous and glandular neoplasia. Immunohistochemical staining was performed for p16(INK4a) and pRb in formalin-fixed, paraffin-embedded tissue sections of the uterine cervix using an indirect immunoperoxidase method. p16(INK4a) staining was detected in 7 of 108 sections (6.5%) of normal squamous mucosa, in scattered ciliated columnar cells in 33 of 88 sections (37.5%) of normal endocervical glands, in 9 of 30 sections (30%) with Nabothian cysts, and in 4 of 4 areas (100%) of tubal metaplasia. In contrast, strong p16(INK4a) staining was found in 13 of 18 cases (72.2%) of cervical intraepithelial neoplasia (CIN) I and in all cases of CIN II/III (n = 46), squamous cell carcinoma (n = 18), endocervical glandular dysplasia (n = 10), adenocarcinoma in situ (n = 23), and invasive adenocarcinoma (n = 12). pRb expression was detected in each diagnostic category; however, the proportion of pRb-positive cells was relatively decreased in high-grade premalignant and malignant lesions of the squamous and endocervical mucosa and showed a generally inverse correlation with the expression of p16(INK4a) at the tissue level. These findings confirm a correlation between the expression of p16(INK4a) and pRb in cervical neoplasias and indicate that p16(INK4a) is a specific marker for premalignant and malignant lesions of the squamous and endocervical mucosa.     

p16INK4A overexpression and HPV infection in uterine cervix adenocarcinoma

Human papillomaviruses (HPVs) are causally involved in the genesis of cervical carcinomas and their precursors, and there is a strong relationship between the cyclin-dependant kinase inhibitor p16^INK4A and HPV infection. This study was carried out to assess the correlations between p16^INK4A expression as an early biomarker of the endocervical adenocarcinoma and HPV infection. p16^INK4A expression and HPV typing were performed on 46 samples including 5 normal endocervix, 9 benign lesions of the endocervix, 25 endocervical adenocarcinomas, and 7 endometrioid adenocarcinomas of the uterine corpus. A semiquantification of the p16^INK4A immunostaining was realized (using both the staining intensity and the percentage of positive cells) and was graded from 0 to 15. All of the 25 endocervical adenocarcinomas overexpressed p16^INK4A; the adjacent epithelium and the connective tissue were strictly negative. No p16^INK4A was detected in nine benign endocervical lesions and in five normal endocervix. Few endometrioid adenocarcinomas of the uterine corpus that infiltrate the endocervix exhibited a low immunoreactivity (score 0/15 or 1/15). This pattern of expression is significantly associated with HPV infection (p<10 ⁻³), mainly high-risk HPV types (p=0.02). Our results suggest that p16^INK4A is a putative molecular biomarker that consistently discriminates uterine cervix adenocarcinomas from benign lesions and from endometrioid adenocarcinomas of the uterine corpus .     

High‐risk human papillomavirus load and biomarkers in cervical intraepithelial neoplasia and cancer

The purpose of this study was to examine the implication of high‐risk human papillomavirus (HPV) load in cervical intraepithelial neoplasia (CIN) and cancer, and to detect biomarkers in cervical disease. We conducted high‐risk HPV DNA load and cervical cytology tests in 343 women, cervical tissue biopsy in 143 women, and immunohistochemistry for p16^INK4A, cyclin D1, p53, cyclooxygenase‐2, Ki‐67, GLUT1, hPygopus2, and beta‐catenin. As a result, HPV load [relative light units (RLU) value] was correlated with the histological severity of cervical disease (p < 0.05). In the ‘atypical squamous cells of undetermined significance’ cytology group, 2.385 of HPV load seemed to be the cut‐off value at which ‘benign’ or CIN I can be differentiated from ‘CIN II or more severe’ (AUC = 0.712), but not statistically significant. The relative risk (odds ratio) of p16^INK4A and GLUT1 overexpression increased gradually according to the histological severity of cervical disease. The p16^INK4A showed statistically significant odds ratios in CIN II, CIN III, and cancer; GLUT1, in CIN II and CIN III; hPygopus2, in CIN III; and beta‐catenin, in CIN III and cancer. Conclusively, HPV load, p16^INK4A, and GLUT1 can be instrumental in predicting the severity of HPV‐related cervical disease. The beta‐catenin/hPygopus2 signaling may be involved in proceeding to CIN III.     

Immunohistochemical expression of p16(INK4a) is predictive of HR-HPV infection in cervical low-grade lesions.

The p16(INK4a) is a cyclin-dependent kinase inhibitor that decelerates the cell cycle by inactivating the cyclin-dependent kinases involved in the phosphorylation of the retinoblastoma protein (RB). Expression of E6 and E7 oncogenes of high-risk (HR) human papillomavirus (HPV), affecting the RB-p16 pathway, leads to p16 upregulation. Although it is widely reported that p16 is overexpressed in a high percentage of preneoplastic lesions and in almost all carcinomas of the uterine cervix, protein upregulation and its correlation with HPV infection in low-grade lesions is still being debated. In this study, we investigated in parallel, p16 expression and HPV infection in 100 cervical biopsies (17 normal tissues, 54 CIN1, 10 CIN2, 11 CIN3, eight invasive squamous cancers). Results obtained demonstrated that none of the 17 normal cervical tissues, evaluated by immunohistochemistry, presented p16 positivity whereas, starting from CIN1 (31%) to CIN2 (90%), CIN3 (100%) and carcinomas (100%), a constant and significant increase of protein overexpression (P<0.0001) was observed. In addition, p16 overexpression consistently showed elevated sensitivity (84%) and specificity (98%) in detecting HR-HPV infection with a high positive predictive value (97%) and negative predictive value (86%). Of interest, 93% of the p16-positive CIN1 were also HR-HPV infected. Our findings confirmed that p16 overexpression is associated to high-grade precancerous lesions and cervical carcinomas, and further demonstrated that immunohistochemical evaluation of p16 may be a useful biomarker in identifying HR-HPV-infected low-grade lesions.     

Immunostaining of p16INK4a/Ki-67 and L1 Capsid Protein on Liquid-based Cytology Specimens Obtained from ASC-H and LSIL-H Cases

Background: Atypical squamous cell cannot exclude high-grade squamous intraepithelial lesion (ASC-H) and low-grade intraepithelial lesion cannot exclude high-grade squamous intraepithelial lesion (LSIL-H) are ambiguous diagnostic entities for the prediction of high-grade cervical lesion. Objective and reproducible tests for predicting high-grade cervical lesions are needed to reduce unnecessary colposcopic referrals or follow-ups.Objective: We aimed to identify an adequate set of adjunctive markers to predict cervical intraepithelial neoplasia grade 2+ (CIN2+) in residual liquid-based cytology specimens (LBCS).Methods: We conducted p16 ^INK4a/Ki-67 and L1 capsid protein immunostaining and human papillomavirus (HPV) DNA typing on 56 LBCS diagnosed with ASC-H or LSIL-H, all of which were subjected to histologic confirmation or follow-up cytologic examination.Results: Positivity for p16 ^INK4a/Ki-67 was associated with a histology of CIN2+ (P=0.047) and CIN3+ (P=0.002). Negativity for L1 capsid protein was associated with CIN2+ confirmed at follow-up (P=0.02).Positivity for high-risk HPV (HR-HPV) was associated with CIN2+ confirmed at follow-up (P=0.036) and a histology of CIN2+ (P=0.037). The sensitivity, specificity, positive predictive value, and negative predictive value for predicting follow-up CIN2+ were 76.2%, 51.4%, 48.5%, and 78.3%, respectively, for p16 ^INK4a/Ki-67 immunostaining; 95.2%, 34.3%, 46.5%, and 92.3%, respectively, for L1 capsid protein; and 66.7%, 67.7%, 54.5%, and 77.8%, respectively, for HR-HPV. The classification and regression tree analysis showed that the combined results of p16 ^INK4a/Ki-67 andL1 capsid protein immunostaining and the HR-HPV test, conducted sequentially, correctly classified 81.8% of samples (27/33)in the prediction of a histology of CIN2 + in ASC-H or LSIL-H. For determination of the histology of cervical intraepithelial neoplasia grade 3+ (CIN3+)in ASC-H or LSIL-H, we found that the combined results of p16 ^INK4a/Ki-67 and L1 capsid protein immunostaining correctly classified 78.8% (26/33) of samples.Conclusions: p16^INK4a/Ki-67 and L1 capsid protein immunostaining and HR-HPV testing of residual LBCS diagnosed with ASC-H or LSIL-H are useful objective biomarkers for predicting CIN2+. Immunostaining for p16^INK4a/Ki-67 and L1 capsid protein are sufficient to predict CIN3+.     

Human papillomavirus genotyping by oligonucleotide microarray and p16 expression in uterine cervical intraepithelial neoplasm and in invasive carcinoma in Korean women

For evaluating the diagnostic significance of p16(INK4A) over-expression in the uterine cervical intraepithelial neoplasm and in invasive carcinoma, human papillomavirus (HPV) was detected and genotyped by oligonucleotide microarray in archival tissues of 117 cervical specimens, including 47 invasive squamous cell carcinomas (SCC), 30 cases of cervical intraepithelial neoplasia (CIN), 20 adenocarcinomas, and 20 cases of non-neoplastic cervix. The expression of p16(INK4A) protein was immunohistochemically studied in these cases and in five HPV-positive and one HPV-negative cervical cancer cell lines. HPV was detected in 50% of CIN, 61.7% of SCC, and 45.5% of adenocarcinomas. p16(INK4A) expression was seen in all 20 cases of adenocarcinoma, 78.7% (37/47) of SCC, and 96.7% (29/30) of CIN, but not in any cases of the non-neoplastic cervix. There was no difference in p16(INK4A) expression between the HPV-positive and HPV-negative cervical lesions. All HPV-positive and -negative cervical cancer cell lines expressed p16(INK4A) protein. In conclusion, the presence of p16(INK4A) expression in cervical squamous and glandular epithelium indicates the existence of dysplasia or malignancy in the uterine cervix, regardless of HPV infection.     

Significance of cyclin E, p16ink4a and ki67 Overexpression in Cervical Exfoliated-cell Specimens for Primary Screening of HPV-related Cervical Carcinoma

Cervical carcinoma is one of the worldwide diseases in de-veloping countries. Cancer of the uterine, with a relativefrequency of 15% of all cancer of women, is ranked sec-ond [ 1 ] . Moreover, recent study has revealed that themorbid age of cervical neopl…     

Etiological correlation of human papillomavirus infection in the development of female bladder tumor

The critical factors and etiological role of human papillomavirus (HPV) infection in the development of female bladder tumor were examined. Eighty‐four female patients with primary bladder tumor were studied. After DNA extraction from each paraffin‐embedded tissue, HPV‐DNA and genotype were checked. In cases of all HPV‐positive cases and some HPV‐negative cases, in situ hybridization (ISH) for high‐risk HPV‐DNA, and immunohistochemical analysis for p16‐INK4a were performed. HPV‐DNA was detected in 5 (6.0%) of 84 eligible patients, and HPV16 was detected in 3 patients, and HPV6 and HPV52 was detected in one case, respectively. HPV‐DNA was detected frequently in younger patients and in patients with a history of cervical cancer. In four high‐risk HPV‐positive cases, high‐risk HPV‐DNA was present in tumor tissues, and p16‐INK4a was expressed moderately or strongly. Two cases had a past history of cervical cancer. In these 2 cases, the same HPV type (HPV16) was detected from bladder tumor and cervical cancer. High‐risk HPV‐DNA ISH signals and p16‐INK4A expression were also detected widely in these cervical cancer tissues. HPV infection is likely to play an important role in the development of female bladder tumor at younger cases with a past history of cervical cancer.     

p16 overexpression in precancerous and cancerous lesions of the uterine cervix in Tunisian women

Uterine cervix cancer is an important public health problem in developing countries. However, there is a substantial lack of inter-observer diagnostic reproducibility for its precursor lesions (CIN1). The study was performed to evaluate the usefulness of p16^INK4A overexpression as a surrogate marker for uterine cervix precancerous lesions and high-risk human papillomavirus (HPV) infection.     

人乳头状瘤病毒阴性的宫颈癌及其癌前病变中p16INK4A蛋白表达和DNA倍体分析

目的探讨人乳头状瘤病毒（HPV）感染阴性的宫颈癌及其癌前病变中p16^INK4A蛋白表达和DNA倍体分析的临床病理学意义。方法应用PCR方法筛查出HPV感染阴性的20例慢性宫颈炎、20例宫颈上皮内瘤变（CIN）、3例宫颈腺上皮内瘤变（CGIN）、38例浸润性鳞状细胞癌（鳞癌）和15例浸润性腺癌作为研究对象。应用免疫组织化学（LSAB）染色方法检测p16^INK4A蛋白在这些病变组织中的表达,并结合流式细胞仪DNA倍体分析探讨HPV阴性的宫颈癌的早期诊断和预后判定。结果p16^INK4A蛋白特异性地表达在CIN和CGIN病变、鳞癌以及腺癌细胞的胞核和胞质中,而在正常鳞状上皮和腺上皮中没有任何阳性表达信号。另外,DNA异倍体在浸润性鳞癌和腺癌中的表达率明显高于CIN病变组（P〈0．01）。在有淋巴结转移的浸润癌中DNA异倍体存在的百分率高于无淋巴结转移组,但尚未发现差异有统计学意义。在8例p16^INK4A表达阴性的浸润性鳞癌中有2例表现为DNA异倍体。结论p16^INK4A蛋白检测可以作为HPV感染阴性的宫颈鳞癌及腺癌的早期诊断指标,结合DNA倍体分析将对宫颈恶性肿瘤的诊断有重要的辅助意义。     

p16(INK4a) promoter methylation and 9p21 allelic loss in colorectal carcinomas: relation with immunohistochemical p16(INK4a) expression and with tumor budding

In colorectal carcinomas, p16(INK4a) inactivation is known to occur by allelic loss and by promoter methylation, but mutations are rare. p16(INK4a) is up-regulated in tumor buds, and the consequent shutdown of proliferation may be a prerequisite for tumor budding. Fifty-seven colorectal carcinomas from a consecutive series were investigated. Using DNA from tissue homogenates, p16(INK4a) promoter methylation was seen in 17 of 57 tumors by methylation-specific polymerase chain reaction, and this could be confirmed using DNA from laser-capture microdissected material in 16 of these cases. A total loss of immunohistochemical p16(INK4a) expression was seen in 6 of 17 tumors with promoter methylation. Quantification of immunohistochemical p16(INK4a) expression for the remaining 11 cases revealed statistically lower frequencies of expression as compared with cases without p16(INK4a) promoter methylation. 9p21 allelic loss was observed in 9 cases, but p16(INK4a) expression in these carcinomas was not reduced. Attempted linear regression of p16(INK4a) expression in tumor buds on the degree of tumor budding, as counted on pan-cytokeratin immunostains, did not show a correlation. p16(INK4a) promoter methylation can completely abrogate p16(INK4a) expression in colorectal carcinomas. In many cases, however, it has an appreciable but only modulatory influence on p16(INK4a) expression. Possibly, methylations are heterozygous, and/or mosaic in colorectal carcinomas and/or methylations are not totally stable but can be lost between carcinoma cell replication cycles. Up-regulation of p16(INK4a) does not seem to be a strict requirement for tumor budding, hence, the absence of a correlation.