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.     

P16 overexpression and human papillomavirus infection in small cell carcinoma of the uterine cervix

Carcinogenesis of cervical cancer has been investigated, and p16(INK4a) overexpression in squamous cell carcinoma of the cervix has been reported as a result of infection by human papillomavirus (HPV) (eg, HPV 16), and the consequence of the retinoblastoma (Rb) protein inactivation by HPV E7 protein. However, to our knowledge, there have been no studies on the relation between p16(INK4a) overexpression associated with HPV and small cell carcinoma of the cervix, which behaves more aggressively clinically than squamous cell carcinoma. The purpose of this study was to determine whether p16(INK4a) is overexpressed in small cell carcinoma, and if p16(INK4a) is overexpressed, the types of HPV that are related to this cancer. We reviewed 10 cases of small cell carcinoma and examined them for p16(INK4a) overexpression by immunohistochemistry. We also performed HPV typing with polymerase chain reaction (PCR)-sequencing analysis and in situ hybridization and found that p16(INK4a) was overexpressed in every case. PCR-sequencing analyses revealed that all cases were HPV-positive and that 9 cases were positive for HPV 18. Five of the 9 cases positive for HPV 18 were also positive by in situ hybridization and yielded a punctate signal, considered to represent the integrated form. In conclusion, p16(INK4a) was overexpressed and HPV 18 was frequently detected in an integrated form in small cell carcinoma. Therefore, inactivation of Rb protein by HPV 18 E7 protein may be associated with carcinogenesis of small cell carcinoma the same as inactivation of Rb protein by HPV 16 E7 protein is associated with carcinogenesis of squamous cell carcinoma.     

siRNA干扰 BMI-1 基因对膀胱癌EJ细胞增殖的调控作用及其机制

目的: 对比观察膀胱癌EJ细胞及人膀胱移行上皮细胞中 BMI-1 基因及下游 p16^INK4a、p14^ARF 基因的mRNA及蛋白表达水平,探讨siRNA干扰 BMI-1 基因后对EJ细胞增殖的影响及其调控机制。方法: 细胞免疫荧光观察BMI-1、p16^INK4a和p14^ARF蛋白在EJ细胞中表达情况及定位。Real-time RT-PCR检测EJ细胞及膀胱正常移行上皮细胞中3种基因的表达水平,Western blotting检测蛋白水平。构建干扰 BMI-1 基因siRNA,通过脂质体转染导入EJ细胞中,设立空白对照和阴性干扰对照组,检测 BMI-1 及下游 p16、p14 基因表达水平及蛋白表达水平的变化;以CCK-8检测细胞生长观察siRNA干扰 BMI-1 表达对EJ细胞增殖的抑制作用;用流式细胞术分析细胞凋亡的改变。结果: BMI-1mRNA及蛋白水平在EJ细胞表达高于膀胱移行上皮细胞,而p16^INK4a和p14^ARFmRNA及蛋白在EJ细胞表达水平稍低于膀胱移行上皮细胞。siRNA干扰 BMI-1 后可以上调EJ细胞中其下游p16和p14 mRNA及蛋白水平,使EJ细胞增殖能力下降,细胞凋亡增多。结论: siRNA干扰 BMI-1 基因表达对EJ细胞的体外生长具有明显的抑制作用,其作用机制与上调其下游 p16^INK4a、p14^ARF 基因的表达有关。     

乳腺癌中p16INK4a和视网膜母细胞瘤基因甲基化状况及其表达

目的 研究乳腺癌及癌旁增生组织中p16INK4a和视网膜母细胞瘤(RB)基因启动子区域的甲基化状况,并探讨基因异常甲基化与蛋白表达及其临床意义.方法 采用甲基化特异性PCR方法 对46例乳腺癌、22例癌旁增生组织及7例正常乳腺组织中p16INK4a和RB基因启动子区域甲基化状况进行检测,并采用免疫组织化学SP法对p16INK4a蛋白表达情况进行相应检测.结果 乳腺癌、癌旁增生组织和正常乳腺组织中p16INK4a基因的甲基化率分别为23.9%(11/46)、18.2%(4/22)、1/7;RB基因的甲基化率分别为10.8%(5/46)、9.1%(2/22)、0(0/7);肿瘤组织、癌旁增生组织和正常乳腺组织中p16INK4a基因、RB基因甲基化率差异均无统计学意义(P>0.05).正常乳腺组织、癌旁增生组织、乳腺癌中p16INK4a蛋白表达阳性率分别为7/7、60.8%(28/46)和81.8%(18/22),三者之间差异无统计学意义(P>0.05);肿瘤组织中p16INK4a蛋白表达与肿瘤分级相关(P<0.05);肿瘤组织中p16INK4a甲基化状况与其蛋白表达、肿瘤分级、ER表达阴性具有相关性(P<0.05),与肿瘤大小、淋巴结转移、年龄均不相关;RB基因甲基化状态与肿瘤分级、肿瘤大小、ER表达及年龄均无相关性,但与淋巴结转移相关(P<0.05).结论 p16INK4a基因异常甲基化可能在乳腺癌发生过程中作用有限,但在肿瘤的演进中发挥作用;RB基因甲基化检测对于分析乳腺癌进展及预后情况可能有一定参考价值;p16INK4a基因甲基化是p16INK4a蛋白失表达的机制之一.     

乳腺癌中p16INK4a和视网膜母细胞瘤基因甲基化状况及其表达

目的 研究乳腺癌及癌旁增生组织中p16INK4a和视网膜母细胞瘤(RB)基因启动子区域的甲基化状况,并探讨基因异常甲基化与蛋白表达及其临床意义.方法 采用甲基化特异性PCR方法 对46例乳腺癌、22例癌旁增生组织及7例正常乳腺组织中p16INK4a和RB基因启动子区域甲基化状况进行检测,并采用免疫组织化学SP法对p16INK4a蛋白表达情况进行相应检测.结果 乳腺癌、癌旁增生组织和正常乳腺组织中p16INK4a基因的甲基化率分别为23.9%(11/46)、18.2%(4/22)、1/7;RB基因的甲基化率分别为10.8%(5/46)、9.1%(2/22)、0(0/7);肿瘤组织、癌旁增生组织和正常乳腺组织中p16INK4a基因、RB基因甲基化率差异均无统计学意义(P>0.05).正常乳腺组织、癌旁增生组织、乳腺癌中p16INK4a蛋白表达阳性率分别为7/7、60.8%(28/46)和81.8%(18/22),三者之间差异无统计学意义(P>0.05);肿瘤组织中p16INK4a蛋白表达与肿瘤分级相关(P<0.05);肿瘤组织中p16INK4a甲基化状况与其蛋白表达、肿瘤分级、ER表达阴性具有相关性(P<0.05),与肿瘤大小、淋巴结转移、年龄均不相关;RB基因甲基化状态与肿瘤分级、肿瘤大小、ER表达及年龄均无相关性,但与淋巴结转移相关(P<0.05).结论 p16INK4a基因异常甲基化可能在乳腺癌发生过程中作用有限,但在肿瘤的演进中发挥作用;RB基因甲基化检测对于分析乳腺癌进展及预后情况可能有一定参考价值;p16INK4a基因甲基化是p16INK4a蛋白失表达的机制之一.     

乳腺癌中p16INK4a和视网膜母细胞瘤基因甲基化状况及其表达

目的 研究乳腺癌及癌旁增生组织中p16INK4a和视网膜母细胞瘤(RB)基因启动子区域的甲基化状况,并探讨基因异常甲基化与蛋白表达及其临床意义.方法 采用甲基化特异性PCR方法 对46例乳腺癌、22例癌旁增生组织及7例正常乳腺组织中p16INK4a和RB基因启动子区域甲基化状况进行检测,并采用免疫组织化学SP法对p16INK4a蛋白表达情况进行相应检测.结果 乳腺癌、癌旁增生组织和正常乳腺组织中p16INK4a基因的甲基化率分别为23.9%(11/46)、18.2%(4/22)、1/7;RB基因的甲基化率分别为10.8%(5/46)、9.1%(2/22)、0(0/7);肿瘤组织、癌旁增生组织和正常乳腺组织中p16INK4a基因、RB基因甲基化率差异均无统计学意义(P>0.05).正常乳腺组织、癌旁增生组织、乳腺癌中p16INK4a蛋白表达阳性率分别为7/7、60.8%(28/46)和81.8%(18/22),三者之间差异无统计学意义(P>0.05);肿瘤组织中p16INK4a蛋白表达与肿瘤分级相关(P<0.05);肿瘤组织中p16INK4a甲基化状况与其蛋白表达、肿瘤分级、ER表达阴性具有相关性(P<0.05),与肿瘤大小、淋巴结转移、年龄均不相关;RB基因甲基化状态与肿瘤分级、肿瘤大小、ER表达及年龄均无相关性,但与淋巴结转移相关(P<0.05).结论 p16INK4a基因异常甲基化可能在乳腺癌发生过程中作用有限,但在肿瘤的演进中发挥作用;RB基因甲基化检测对于分析乳腺癌进展及预后情况可能有一定参考价值;p16INK4a基因甲基化是p16INK4a蛋白失表达的机制之一.     

Pathogenetic and biologic significance of TP14ARF alterations in nonsmall cell lung carcinoma

The INK4a/ARF locus on human chromosome band 9p21 carries two tumor suppressor genes, TP14ARF and TP16INK4a, and both are frequently inactivated in nonsmall cell lung carcinoma (NSCLC. TP14ARF and TP16INK4a play important roles in the TP53 and RB tumor suppressor pathways, respectively. To elucidate the genetic and epigenetic status of the TP14ARF and TP16INK4a genes in NSCLC, we comprehensively analyzed mutations, homozygous deletions, methylations in the CpG regions, and expression of the TP14ARF and TP16INK4a genes in 31 NSCLC cell lines. TP16INK4a (84%) was inactivated more frequently than TP14ARF (55%). Moreover, p16INK4a was inactivated in all 17 cell lines with TP14ARF inactivation. Three cell lines with base substitutions in exon 2 resulted in missense mutations of TP16INK4a but silent mutations of TP14ARF. There was a case of mutation in exon 1alpha unique to TP16INK4a, but not a mutation in exon 1beta unique to TP14ARF. The TP16INK4a gene was methylated in 6 cell lines, but the TP14ARF gene was not methylated in any cell line. Unlike a mutually exclusive relationship for inactivation between TP16INK4a and RB, TP14ARF and TP53 did not show such a relationship (P = 0.61, Fisher exact test). Thus, the present results indicate the TP16INK4a gene to be the primary target of INK4a/ARF locus alterations. Transient TP14ARF expression induced G1 arrest in the cells with wild-type TP53, but not in the cells with mutated TP53. Thus, the pathogenetic and biologic significance of TP14ARF inactivation is different between NSCLC cells with wild-type TP53 and those with mutated TP53.     

Cellular Expression of INK4a Gene in Cells of Bladder Cancer Associated with Human Papilloma Virus-16

Hyperexpression of p16(INK4a) protein is an early marker of cervical cancer. Hyperexpression of INK4a gene encoding this protein at the level of mRNA and p16(INK4a) was detected in tumor cells of some patients with bladder cancer associated with human papilloma virus-16. However, in contrast to cervical cancer, this phenomenon in urothelial carcinomas does not correlate with expression of human papilloma virus-16 oncogenes E6 and E7.     

Alterations in the INK4a/ARF locus and their effects on the growth of human osteosarcoma cell lines

Two different proteins, p16(INK4a) and p14(ARF), encoded by the INK4a/ARF locus play important roles in the RB and p53 pathways, respectively. This study was performed to determine genetic and epigenetic alterations in the INK4a/ARF locus and their effects on the growth of osteosarcoma. Among six cell lines examined, both p16(INK4a) and p14(ARF) exons were homozygously deleted in two cell lines, MG63 and HOS, and both p16(INK4a) and p14(ARF) promoters were methylated in one cell line, U2OS. Wild-type mRNA and proteins for p16(INK4a) and p14(ARF) were expressed in three other cell lines, SaOS2, HuO9, and G292. Transfection studies were performed using two cell lines, U2OS and MG63. Both the RB and p53 genes were wild types in U2OS, whereas p53 but not RB was mutated in MG63. Both p16(INK4a) and p14(ARF) suppressed the growth of U2OS, whereas p16(INK4a) but not p14(ARF) suppressed the growth of MG63. p53 only did not suppress the growth of MG63 either; however, coexpression of p14(ARF) with p53 increased the fraction of the G0/G1 phase in MG63 cells. The data presented here demonstrate the importance of genetic and epigenetic alterations in the INK4a/ARF locus for the growth of osteosarcoma and thus will be useful to further understand the biologic behavior of osteosarcoma in association with the defects in the p53 and RB pathways.     

Promoter methylation status of multiple genes in brain metastases of solid tumors

The aberrant methylation of the CpG island promoter regions acquired by tumor cells is one mechanism for loss of gene function. The high methylation rate for RB1 and death-associated protein-kinase gene (DAP-kinase) (60 and 90%, respectively) previously found in brain metastases suggests this mechanism could be non-randomly associated to tumor progression and metastasis. Thus, in addition to these two genes, we determined the methylation status of the genes p16INK4a, glutathione S-transferase P1 (GSTP1), O6-methylguanine DNA methyltransferase (MGMT), thrombospondin-1 (THBS1), p14ARF, TP53, p73, and tissue inhibitor of metalloproteinase 3 (TIMP-3), in 18 brain metastases of solid tumors, with methylation specific PCR. The metastases were derived from malignant melanoma (three cases), lung carcinoma (six cases), breast carcinoma (three cases), ovarian carcinoma (two cases) and one each from colon, kidney, bladder and undifferentiated carcinoma. We detected methylation levels in the tumor samples of 83% in p16INK4a, 72% in DAP-kinase, 56% in THBS1, 50% in RB1, 39% in MGMT, 33% in GSTP1 and p14ARF each, 22% in p73 and TIMP-3 each, and 11% in TP53. The methylation index (number of genes methylated/number of genes tested) varied between 0.1 and 0.6, with an average of 0.42, indicating that a high grade of gene methylation accumulates parallel to the tumor metastasis process. Our data suggest an important role for gene methylation in the development of brain metastases, primarily involving epigenetic silencing of DAP-kinase, THBS1 and the cell-cycle regulators RB1/p16INK4a.     

HPV infection and p16INK4A and TP53 expression in rare cancers of the uterine cervix

Cervix cancer remains among most commonly diagnosed cancer in developing countries. Except squamous cell carcinoma and adenocarcinoma, the etiopathology and oncogenic mechanisms of rare cancers remain largely unknown. The study was performed to investigate the value of HPV infection and the expression of p16^INK4A and TP53 in rare primitive cancers of the cervix.We conducted a retrospective study of rare primitive cancers of the cervix. Main clinicopathological features were reported. HPV infection was detected by in situ hybridization. Expression of p16^INK4A and TP53 was analyzed by immunohistochemistry.Overall, seven cases were identified, including basaloid squamous cell carcinoma (BSCC, n?=?2), small cell neuroendocrine carcinoma (SCNEC), granulocytic sarcoma without acute myeloid leukemia, leiomyosarcoma, primitive neuroectodermal tumor and botryoid-type embryonic rhabdomyosarcoma. The mean age of patients was 53.7 years. Four cancers were diagnosed at advanced stages. The prognosis was unfavorable and associated with patient death in five cases. HPV types 16/18 were detected in BSCCs and SCNEC. Strong and diffuse p16^INK4A overexpression was described in the nucleus and the cytoplasm of all tumor cells of BSCCs and SCNEC. The remaining cancers exhibited only scattered and focal p16^INK4A staining. Mutated TP53 protein was detected in BSCC (case 1) and GS.Rare cancers of the cervix are aggressive and associated with poor prognosis. In contrast to mesenchymal tumors, BSCCs and SCNEC are etiologically related to high-risk HPV infection and could be identified by block positive p16^INK4A overexpression as common cancers of the cervix. TP53 mutations are not a negligible genetic event in rare cervical cancers.     

Molecular analysis of the INK4A and INK4B gene loci in human breast cancer cell lines and primary carcinomas

The INK4A and INK4B loci are located at 9p21 and have been implicated in the tumorigenesis of various human malignancies. The INK4A gene encodes two cell cycle regulators, p16(INK4A) and ARF, while INK4B encodes p15(INK4B). Previously, we have shown that the p16(INK4) tumor suppressor was not mutated or deleted in primary breast carcinomas. However, primary and metastatic breast carcinomas exhibited a relative hypomethylation of p16(INK4A), which is associated with expression, compared to normal breast tissue. The present study was conducted to determine if inactivation of p15(INK4B) and INK4A exon 1beta (ARF) are common events in breast carcinoma. Mutational analysis was performed by PCR-SSCP, and mRNA expression was evaluated by RT-PCR. Methylation-specific PCR was used to determine the methylation status of the p15(INK4B) promoter. Our results demonstrate that the p15(INK4B) gene was altered in 3 (21%) of the 14 breast cell lines; one had a silent mutation and two had homozygous deletion of the gene. None of the cell lines showed methylation of p15(INK4B). Two (14%) cell lines had homozygous deletion of INK4A exon 1beta. All normal and malignant breast tissue samples were wild-type and non-methylated for p15(INK4B) and wild-type for exon 1beta. Our results show that these structurally and functionally related genes are not invariably affected together, and the most frequently observed alteration at the INK4A and INK4B loci in breast carcinoma appears to be p16(INK4A) hypomethylation.     

Retinoblastoma protein function and p16INK4a expression in actinic keratosis, squamous cell carcinoma in situ and invasive squamous cell carcinoma of the skin and links between p16INK4a expression and infiltrative behavior.

p16INK4a is involved in many important regulatory events in the cell and the expression and function is closely associated with the retinoblastoma protein (Rb). Earlier, we have in colorectal cancer and in basal cell carcinoma showed that p16INK4a is upregulated at the invasive front causing cell cycle arrest in infiltrative tumor cells via a functional Rb. This role for p16INK4a as a regulator of proliferation when tumor cells infiltrate might besides a general cyclin-dependent kinase (cdk) inhibitory effect explain why p16INK4a is deregulated in many tumor forms. The expression pattern of p16INK4a in relation to Rb-function in squamous cancer and precancerous forms of the skin has not been fully detailed. We therefore characterized the expression of p16INK4a, Rb-phosphorylation and proliferation in actinic keratosis, squamous cell carcinoma in situ and invasive squamous cell carcinoma with special reference to infiltrative behavior. The expression of p16INK4a varied between the lesions, with weak and cytoplasmic p16INK4a expression and functional Rb in actinic keratosis. Strong nuclear and cytoplasmic p16INK4a expression was observed in all carcinomas in situ in parallel with lack of Rb-phosphorylation but high proliferation indicating a nonfunctional Rb. Invasive squamous carcinoma showed a mixed p16INK4a expression pattern where some tumors had strong cytoplasmic p16INK4a expression, large fraction of Rb-phosphorylated cells and high proliferation. Interestingly, despite this disability of p16INK4a to inhibit proliferation there was an upregulation of cytoplasmic p16INK4a in infiltrative cells compared to tumor cells towards the tumor center. A similar scenario but strong and combined nuclear and cytoplasmic p16INK4a expression in infiltrative cells, was observed in other invasive squamous cancers. This suggests that the p16INK4a upregulation in infiltrative cells is governed independently of the subcellular localization or of the potential to affect proliferation via Rb, and suggests a potentially proliferation independent function for p16INK4a in infiltrative behavior.     

p16ink4 immunoreactivity is a reliable marker for urothelial carcinoma in situ

Morphological discrimination of urothelial carcinoma (UC) in situ, a precursor of high-grade invasive carcinoma, from severe reactive atypia is essential, but can be challenging at times. Mutations of the cell cycle regulatory gene INK4a (located at 9p21) that encodes p16(INK4) are one of the critical early events in carcinogenesis of UC. The purpose of this study was to investigate p16(INK4) expression in different urothelial lesions and assess its possible utility in distinguishing reactive versus neoplastic changes. Immunoreactivity of p16(INK4) was investigated using paraffin sections from 8 different sample groups (n = 80), including organ donor bladders with normal and/or reactive urothelium; bladder biopsies with reactive atypia; isolated carcinoma in situ; high-grade UC with concurrent carcinoma in situ; low-grade papillary urothelial neoplasms; high-grade stage T1 UC; and high-grade stage T2-T4 UC without concomitant carcinoma in situ. A composite staining score was calculated (Sigma% positive cells x intensity) for each case. Fluorescence in situ hybridization analysis was performed in selected cases. A uniform and weak cytoplasmic p16(INK4) expression was observed in normal urothelium and urothelium with reactive atypia from organ donors. Bladder biopsies with reactive atypia showed lower scores and loss of p16(INK4) expression in 38% of cases. Strong p16(INK4) staining was found in 100% of carcinoma in situ with no loss of p16(INK4) expression. The strong p16(INK4) immunoreactivity in foci of carcinoma in situ clearly demarcated the neoplastic cells from adjacent nonneoplastic cells, which showed either normal or focal loss of p16(INK4) staining. Fluorescence in situ hybridization study revealed abundant deletion of chromosome 9p21 or polysomy of chromosome 9 in malignant cells of carcinoma in situ. Increased p16(INK4) expression was also seen in most high-grade invasive UC with concurrent carcinoma in situ, but the intensity of p16(INK4) staining did not correlate with the cancer grade or stage. We conclude that the 16(INK4) immunoreactivity seems to be most useful in distinguishing carcinoma in situ from severe reactive atypia. Alterations of 9p21/chromosome 9 detected by fluorescence in situ hybridization can also be used for diagnostic confirmation and prognostic prediction.     

IMP3 is a novel biomarker for adenocarcinoma in situ of the uterine cervix: an immunohistochemical study in comparison with p16(INK4a) expression.

Adenocarcinoma in situ of the uterine cervix remains a diagnostic challenge in a small proportion of cases. This suggests a need for biomarker that may be of help in establishing the diagnosis. The aim of this study was to evaluate the potential of insulin-like growth factor-II mRNA-binding protein 3 and cyclin-dependent kinase inhibitor p16(INK4a) as biomarkers for adenocarcinoma in situ. Forty-four samples of adenocarcinoma in situ from 40 patients and 23 control cases of benign uterine cervix were included in this study. In addition to benign endocervical epithelium, 19 of these 23 control cases also showed focal tubal metaplasia. Cytoplasmic immunoreactivity for insulin-like growth factor-II mRNA-binding protein 3 was identified in 41 (93%) adenocarcinoma in situ samples, among which, 29 (71%), 10 (24%), and 2 (5%) samples showed insulin-like growth factor-II mRNA-binding protein 3 positive staining in 50% or more, >5 to <50 and <5% of adenocarcinoma in situ lesional cells, respectively. Immunohistochemical reaction intensity for insulin-like growth factor-II mRNA-binding protein 3 was found to be strong in 34 adenocarcinoma in situ samples, intermediate in five, and weak in two. All 23 control cases were negative for insulin-like growth factor-II mRNA-binding protein 3. p16(INK4a) expression was identified in all of the adenocarcinoma in situ samples with intermediate staining intensity seen in seven samples and strong in the remainder. Fourteen of 19 (74%) tubal metaplasia cases showed p16(INK4a) immunoreactivity in >50% of the tubal metaplastic epithelium with staining intensity ranging from weak to strong. Our findings demonstrate significant expression of insulin-like growth factor-II mRNA-binding protein 3 and p16(INK4a) in adenocarcinoma in situ as compared to benign endocervical glands, suggesting that expression of these biomarkers may be helpful in the distinction of adenocarcinoma in situ from benign endocervical glands, particularly in difficult borderline cases.     

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.     

Over-expression of polycomb group protein EZH2 relates to decreased expression of p16 INK4a in cholangiocarcinogenesis in hepatolithiasis

Polycomb group protein EZH2 and Bmi1 are reportedly involved in the progression of malignant tumours. We examined the participation of EZH2 in multi-step cholangiocarcinogenesis in hepatolithiasis with respect to tumour suppressor gene p16 INK4a. We examined 20 hepatolithiatic livers with intrahepatic cholangiocarcinoma (ICC) and 10 histologically normal livers. Neoplastic biliary lesions were classified into biliary intraepithelial neoplasm (BilIN-1, 2 and 3) and invasive carcinoma. We selected 15 foci of invasive carcinoma, 8 BilIN-3 (carcinoma in situ), 12 BilIN-2 (high-grade dysplasia), 32 BilIN-1 (low-grade dysplasia) and 37 non-neoplastic biliary epithelia from these livers. Expression of p16 INK4a, EZH2 and Bmi1 were surveyed in these foci. P16 INK4a promoter methylation was examined in microdissected tissues. Taking advantage of two cell lines of CC (HuCTT-1 and TFK-1) and small interfering RNA (siRNA), the effects of the knockdown of EZH2 on p16 INK4a methylation of CC cells were examined. Expression of p16 INK4a, which was frequent in BilIN1, was decreased in BilIN-2/3 and invasive carcinoma, while EZH2 expression showed step-wise increase from BilIN-1, -2 and -3 to invasive carcinoma (p < 0.01). P16 INK4a promoter hypermethylation was related to aberrant expression of EZH2. The knockdown of EZH2 in cultured CC cells decreased p16 INK4a methylation and decreased binding of EZH2 to the p16 INK4a gene promoter. The latter suggested that direct binding of EZH2 is involved in the regulation of the p16 INK4a gene. Our data suggest that over-expression of EZH2 may induce hypermethylation of p16 INK4a promoter followed by decreased expression of p16 INK4a in the multi-step cholangiocarcinogenesis through intraepithelial neoplasm in hepatolithiasis.     

Senescence and apoptosis in carcinogenesis of cervical squamous carcinoma.

Senescence and apoptosis are two key mechanisms that protect against cancer development. Many cell cycle regulators, such as p14(ARF), p15(INK4b) and p16(INK4a), are important in G1 cell cycle arrest and oncogene-induced senescence. The bcl-2 protein is one of the key components that control apoptosis, while the p53 protein plays key roles in both mechanisms. The genes of these key regulator proteins are often mutated or deleted in various malignancies. It is unknown how senescence and apoptosis are regulated in one of the most common tumors of the female genital tract, cervical squamous cell carcinoma (SCC). In this study the, expression of senescence, apoptosis and proliferation markers in normal cervical epithelium, cervical intraepithelial neoplasia (CIN) and SCC are characterized via immunohistochemical staining for p14(ARF), p15(INK4b), p16(INK4a), bcl-2, p53 and Ki-67 in tissue microarray blocks containing 20 samples each of normal cervix, moderate-to-severe cervical dysplasia (CIN II-III) and invasive SCC. Samples are derived from 60 total cases of cervical biopsies and cervical conizations. Results showed that the proliferation marker, Ki-67, is markedly increased, and the senescence markers, p15(INK4b), p16(INK4a) and p14(ARF) are overexpressed in both dysplasia and carcinoma. P53 immunostain is negative in all normal cervical tissue, and positive in dysplasia and carcinoma. Although the expression of bcl-2 is increased in dysplasia, this marker is negative in approximately half of SCC cases. These results suggest that some senescence pathways are activated and are still maintained in cervical dysplasia and carcinoma. However proliferation is increased and carcinogenesis is not thwarted, leading to eventual development of cervical cancer. Other mechanisms, such as those that account for the apparent overexpression of p53 and paradoxical loss of bcl-2 expression in some SCC cases, as well as additional senescence and apoptotic pathways, may play key roles carcinogenesis of cervical SCC.     

Are human papillomaviruses responsible for the occurrence of bladder cancer

A female patient with recurrent bladder cancer underwent complex examination. The primary tumor removed in 2004 showed human papillomavirus (HPV) 16 DNA, mRNA corresponding to HPV16 oncogene E7, as well as HPV16 protein E7. The patient is a smoker who has been working at a chemical factory for over 20 years. During tumor recurrence in 2009, there was no DNA of high-risk HPV types in the cancer cells. HPV16 E7protein and cellular p 16(INK4alpha), an indicator of HPV-induced carcinogenesis, were not found. Colposcopy revealed no precancerous changes in the epithelium of the cervix uteri. The cervical epitheliocytes contained no high-risk HPV DNA, E7 and p16(INK4alpha) proteins. It seems expedient to continue in vitro studies of the possible role of HPV in urothelial carcinogenesis on an experimental model.