No abstract available.
Cyclin-Dependent Kinase Inhibitor p16* ; Porokeratosis*

BACKGROUND: The p16 protein is a cyclin-dependent kinase inhibitor (CDKI) that inhibits cell cycle progression from phase G1 to phase S in the cell cycle. Many p16 gene mutations have been noted in many cancer-cell lines and in some primary cancers. These mutated genes caused abnormal or aberrant expression of the p16 protein, which might have contributed to the malignant progression of the cells by deranging the cell cycle. This study was to examine the abnormal or aberrant expression of the p16 protein in breast cancer tissue by using p16 protein specific immunohistochemical staining. METHODS: p16-protein-specific immunohistochemical staining was performed on 31 breast-cancer tissue samples. Twenty-four cases among the 31 tissue staining slides simultaneously showed a normal breast-tissue portion on the same staining slide. Microscopic photographs of both the breast-cancer and the normal- tissue portion were taken at the same magnification to compare the statistically analyzed fraction of red or brown colored p16 stained nuclei. RESULTS: In the breast cancer tissue, 7 (22.6%) showed totally negative, with less than 5% of the nuclei staining. The completely negative cases were not related to the stage of the disease (p=0.096) or to the histopathologic grade (p=0.20). The staining ratios of the breast-cancer tissue and the normal tissue were 26.2 ( +/- 18.7)% and 72.4 ( +/- 18.8)%, respectively. In the breast-cancer tissue, the ratio of expression of the p16 protein was significantly lower than in the normal tissue (p=0.001). CONCLUSIONS: In the carcinogenesis of some breast cancers, low expression of the p16 protein may play an important role in the unlimited proliferation of tumor cell due to a loss of the cell-cycle-regulating role of the p16 protein.
Breast Neoplasms* ; Breast* ; Carcinogenesis ; Cell Cycle ; Cyclin-Dependent Kinase Inhibitor p16* ; Genes, p16 ; Humans* ; Phosphotransferases

PURPOSE: An altered cell cycle regulation may underline the development and progression of human malignancies. The purpose of this study was to determine whether the degree of p16(INK4A), Rb and E2F-1 expressions are related to certain parameters such as histologic differentiation, T-stage, lymph node metastasis and TNM stage in colorectal carcinoma. The correlation between the above proteins were compared. METHODS: Immunohistochemical stain was perfomed, for p16(INK4A), Rb and E2F-1 on 84 formalin-fixed paraffin-embedded tissue sections of colorectal adenocarcinomas. RESULTS: The overall expression frequencies of the p16(INK4A), Rb and E2F-1 were 54.8 (46/84), 76.2 (64/84) and 48.8% (41/84), respectively. Loss of the p16(INK4A) expression frequency was higher with a poorly differentiated histologic grade, the presence of nodal metastasis and higher TMN stage. The expression of Rb was not correlated with any of the parameters studied. The frequency of the E2F-1 expression was higher with a poorly differentiated histologic grade, the presence of nodal metastasis and higher TNM stage. A highly significant inverse correlation between the expressions of p16(INK4A) and E2F-1 was observed. CONCLUSION: These data suggest that the loss of p16(INK4A) expression and the expression E2F-1 may play roles in the progression of colorectal adenocarcinomas and could possibly be used as prognostic factors. Further studies to determine the relationships in the expressions of p16(INK4A), Rb and E2F-1 will be required.
Adenocarcinoma ; Cell Cycle ; Colorectal Neoplasms* ; Cyclin-Dependent Kinase Inhibitor p16* ; Humans ; Lymph Nodes ; Neoplasm Metastasis

BACKGROUND: Human papillomavirus (HPV) infection can be detected by in situ hybridization (ISH), in which a punctate signal pattern indicates integrated HPV DNA and a diffuse pattern denotes the presence of episomal viral DNA. This study was conducted to evaluate the usefulness of an HPV ISH assay for invasive cervical cancer. METHODS: The HPV ISH assay for high-risk HPV and immunohistochemical staining for p16(INK4a), p53, bcl-2, and Ki-67 were performed in a tissue microarray of 279 cervical cancers. RESULTS: High-risk HPV ISH was positive in 194 (69.5%) of the samples. Punctate, diffuse, and mixed signal patterns were observed in 157 (56.3%), one (0.4%), and 36 cases (12.9%), respectively. Positive results in high-risk HPV ISH were associated with p16 and bcl-2 expression (p = 0.01 and p < 0.01, respectively). According to a Cox regression analysis, HPV infection and its surrogate immunohistochemical markers such as p16, bcl-2, and Ki-67 were not independent prognostic factors, but stage and grade were independent prognostic factors. CONCLUSIONS: Our results confirm that an HPV ISH assay is reasonably sensitive for HPV infection and that it might be useful to identify integrated HPV DNA in formalin-fixed and paraffin-embedded specimens. Further study encompassing HPV type, E2/E6 ratio, and therapeutic modality is necessary to understand the clinical meaning of HPV status in cervical cancer.
Cyclin-Dependent Kinase Inhibitor p16 ; DNA ; DNA, Viral ; Humans ; In Situ Hybridization ; Uterine Cervical Neoplasms

BACKGROUND: Human papillomavirus (HPV) infection can be detected by in situ hybridization (ISH), in which a punctate signal pattern indicates integrated HPV DNA and a diffuse pattern denotes the presence of episomal viral DNA. This study was conducted to evaluate the usefulness of an HPV ISH assay for invasive cervical cancer. METHODS: The HPV ISH assay for high-risk HPV and immunohistochemical staining for p16(INK4a), p53, bcl-2, and Ki-67 were performed in a tissue microarray of 279 cervical cancers. RESULTS: High-risk HPV ISH was positive in 194 (69.5%) of the samples. Punctate, diffuse, and mixed signal patterns were observed in 157 (56.3%), one (0.4%), and 36 cases (12.9%), respectively. Positive results in high-risk HPV ISH were associated with p16 and bcl-2 expression (p = 0.01 and p < 0.01, respectively). According to a Cox regression analysis, HPV infection and its surrogate immunohistochemical markers such as p16, bcl-2, and Ki-67 were not independent prognostic factors, but stage and grade were independent prognostic factors. CONCLUSIONS: Our results confirm that an HPV ISH assay is reasonably sensitive for HPV infection and that it might be useful to identify integrated HPV DNA in formalin-fixed and paraffin-embedded specimens. Further study encompassing HPV type, E2/E6 ratio, and therapeutic modality is necessary to understand the clinical meaning of HPV status in cervical cancer.
Cyclin-Dependent Kinase Inhibitor p16 ; DNA ; DNA, Viral ; Humans ; In Situ Hybridization ; Uterine Cervical Neoplasms

OBJECTIVETo effectively screen p16 protein expression of different clinical stage nasopharyngeal carcinoma (NPC) by constructing and applying high-throughput tissue microarray/tissue chip.

METHODSA series of tissue chips were prepared by using tissue arrayer with samples from different clinical stage NPC tumors and noncancerous nasopharynx tissue. Specimens from 259 cases of nasopharyngeal lesions were detected immunohistochemically on a tissue chip for p16 protein expression and the correlation of p16 protein expression to clinical stage of NPC was analyzed statistically.

RESULTSp16 protein expression was detected in all 18 histologically normal nasopharyngeal epithelia. No p16 protein was detected in 3 of 3 (100%) stage I NPC, 38 of 44 (86.3%) stage II NPC, 59 of 68 (86.8%) stage III NPC, 23 of 28 (82.1%) stage IV NPC, 87 of 98 (88.8%) unclear stage NPC. The efficiency of p16 protein expression in NPC tissues was significantly lower than that in normal nasopharyngeal epithelia (chi(2) = 82.58, P < 0.001), and there was no apparent relationship between p16 protein expression and clinical stages (chi(2) = 0.09, P = 0.769).

CONCLUSIONSThe frequent deletion of p16 protein in NPC suggests that p16 gene has an important role in the development and progression of NPC. The consistency of p16 protein deletion in different stages of NPC suggests that the deletion of p16 protein is an early event in the development of NPC, and it is feasible to utilize tissue microarray for a rapid, economic and accurate screening of clinical tissue specimens on a large scale.

Cyclin-Dependent Kinase Inhibitor p16 ; biosynthesis ; Humans ; Immunohistochemistry ; Nasopharyngeal Neoplasms ; metabolism ; pathology ; Neoplasm Staging

PURPOSE: Alterations of the p15(INK4B) and p16(INK4A) gene which are separated by 25 kb on chromosome 9p21 have been reported in various tumor derived cell lines and primary tumors, but the role of these genes in cervical cancer is unknown. MATERIAL AND METHOD: To determine the frequency of deletions and point mutations of these genes in human cervical cancer, we examined 57 primary tumors and matched normal tissues, and 3 cervical cancer derived cell lines. All the tumor tissues and cell lines were human papil- INK48 lomavirus (HPV)-positive. Deletions or point mutations of exon 2 of the pl5 gene and exons 1, 2, and 3 of the p16(INK4A) gene were examined by polymerase chain reaction (PCR) and direct sequencing, respectively. RESULT: Our data indicate no evidence for intragenic homozygous deletion or point mutation in the cervical cancer or cervical cancer derived cell lines. INK48 INK4A CONCLUSION: Deletions or point mutations in the p15 or p16 gene may not be required for the development of HPV-positive cervical cancer or for establishment of cervical cancer cell lines.
Cell Line* ; Cyclin-Dependent Kinase Inhibitor p16 ; Exons ; Genes, p16 ; Humans ; Point Mutation ; Polymerase Chain Reaction ; Uterine Cervical Neoplasms

OBJECTIVETo explore the correlation between homozygous deletions and mutation of p16 gene and the carcinogenesis and progression of squamous cell carcinoma of buccal mucosa.

METHODSThirty buccal cancers, 10 leukoplakias and 8 buccal mucosas were involved. DNA was extracted from the tissues. PCR was used to analyses homozygous deletion of p16 gene. PCR-SSCP-DNA sequencing was performed to detect the point mutation of p16 gene. Immunohistochemical techniques were used to detect the expression of P16 protein.

RESULTSGene deletions and point mutations were not found in leukoplakia and normal buccal mucosa. Gene deletions were found in 7 samples out of 30 cases of squamous cell carcinoma of buccal mucosa (23.3%), while point mutations were found in 5 samples out of 30 cases of squamous cell carcinoma of buccal mucosa (16.7%). Sequencing analysis showed that 5 cases point mutations were missense mutations, occurred on exon 2. Three cases occurred in the same point, codon 99 (GAT --> AAT). The result of immunohistochemical stains showed that 11 out of 12 cases gene inactivation did not expressed P16 protein.

CONCLUSIONHomozygous deletion and point mutation of p16 were the main pattern of gene inactivation in squamous cell carcinoma of buccal mucosa. There was a closely correlation between p16 gene inactivation and the carcinogenesis of squamous cell carcinoma of buccal mucosa.

Carcinoma, Squamous Cell ; Cyclin-Dependent Kinase Inhibitor p16 ; Gene Deletion ; Genes, p16 ; Humans ; Mouth Mucosa ; Mutation ; Point Mutation

BACKGROUNDBoth p16(INK4) and p21(Waf1) are tumor suppressors with similar biological functions in the regulation of cellular senescence. Previous reports showed that p16(INK4) could be activated by p21(Waf1) through transcriptional factor Sp1 in HeLa cells. This study was undertaken to determine the effects of p16(INK4) on the expression and functions of p21(Waf1).

METHODSHuman diploid fibroblast 2BS cells were stably transfected with sense (2BS/p16(INK4)), antisense p16(INK4) (2BS/asp16(INK4)) or empty vector (2BS/neo). Then they were assayed by reverse-transcription polymerase chain reaction (RT-PCR), fluorescence activated cell sorting (FACS) and Western blot.

RESULTS2BS/p16(INK4) cells exhibited cell cycle arrest in both G1 and G2/M phases. Endogenous p21(Waf1) protein levels increased twofold in the 2BS/p16(INK4) cells, but not decreased in the 2BS/asp16(INK4) cells. p21(Waf1) mRNA levels were not affected in neither 2BS/p16(INK4) nor 2BS/asp16(INK4) cells.

CONCLUSIONp16(INK4) may play an important role in the regulation of cellular senescence by modulating the p21(Waf1) protein level via the posttranscriptional mechanism.

Cell Cycle ; Cells, Cultured ; Cellular Senescence ; Cyclin-Dependent Kinase Inhibitor p16 ; physiology ; Cyclin-Dependent Kinase Inhibitor p21 ; physiology ; Fibroblasts ; metabolism ; Humans ; Transcription, Genetic

OBJECTIVETo investigate the methylation rate of cyclin-dependent kinase inhibitor 2A (CDKN2A) and cyclin-dependent kinase inhibitor 2B (CDKN2B) in the 9P21 region in children with acute myeloid leukemia (AML) and the association of gene methylation with clinical features and outcomes.

METHODSThe clinical data of 58 children who were newly diagnosed with AML between January 2010 and December 2012 were retrospectively analyzed. Thirty-eight healthy children were recruited as the control group. Genomic DNA was extracted from bone marrow or peripheral blood of the 58 patients and 38 healthy children. The methylation status of CDKN2A and CDKN2B was analyzed by methylation-specific multiplex ligation-dependent probe amplification.

RESULTSGene methylation was not found in healthy children. Methylation probes of 44 patients were detected in 58 patients. The methylation of CDKN2A was detected with 136 bp and 237 bp methylation probes. The methylation of CDKN2B was detected with 130 bp, 210 bp, 220 bp, and 417 bp methylation probes. The methylation rate of CDKN2A was 5%, while the methylation rate of CDKN2B was 76%. The methylation detected by some probes was associated with sex, hemoglobin, and platelet count at the first visit.

CONCLUSIONSThe methylation of CDKN2B is a common event in children with AML, while the methylation of CDKN2A is relatively rare.

Adolescent ; Child ; Child, Preschool ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; DNA Methylation ; Female ; Humans ; Infant ; Leukemia, Myeloid, Acute ; genetics ; Male