BACKGROUND: P16 inactivation is frequently accompanied by telomerase reverse transcriptase ( TERT ) amplification in human cancer genomes. P16 inactivation by DNA methylation often occurs automatically during immortalization of normal cells by TERT . However, direct evidence remains to be obtained to support the causal effect of epigenetic changes, such as P16 methylation, on cancer development. This study aimed to provide experimental evidence that P16 methylation directly drives cancer development. METHODS: A zinc finger protein-based P16 -specific DNA methyltransferase (P16-Dnmt) vector containing a "Tet-On" switch was used to induce extensive methylation of P16 CpG islands in normal human fibroblast CCD-18Co cells. Battery assays were used to evaluate cell immortalization and transformation throughout their lifespan. Cell subcloning and DNA barcoding were used to track the diversity of cell evolution. RESULTS: Leaking P16-Dnmt expression (without doxycycline-induction) could specifically inactivate P16 expression by DNA methylation. P16 methylation only promoted proliferation and prolonged lifespan but did not induce immortalization of CCD-18Co cells. Notably, cell immortalization, loss of contact inhibition, and anchorage-independent growth were always prevalent in P16-Dnmt&TERT cells, indicating cell transformation. In contrast, almost all TERT cells died in the replicative crisis. Only a few TERT cells recovered from the crisis, in which spontaneous P16 inactivation by DNA methylation occurred. Furthermore, the subclone formation capacity of P16-Dnmt&TERT cells was two-fold that of TERT cells. DNA barcoding analysis showed that the diversity of the P16-Dnmt&TERT cell population was much greater than that of the TERT cell population. CONCLUSION P16 methylation drives TERT -mediated immortalization and transformation of normal human cells that may contribute to cancer development.
Humans ; Telomerase/genetics* ; DNA Methylation/physiology* ; Fibroblasts/cytology* ; Cyclin-Dependent Kinase Inhibitor p16/metabolism* ; Cell Line ; Cell Transformation, Neoplastic/genetics*

OBJECTIVE: To investigate paraffin section thickness in immunohistochemical detection of p16 expression in cervical tissue samples. METHODS: p16 immunohistochemical staining was performed in 150 cases of chronic cervicitis, 126 cases of low-grade squamous intraepithelial lesions(LSIL), 96 cases of high-grade squamous intraepithelial lesions (HSIL) and 78 cases of cervical cancer from January 2014 to March 2018 in Zhongshan Boai Hospital. The results of p16 protein expression in paraffin sections with thickness of 2, 3, 4, 5 and 6 μm were compared using Logistic regression analysis. RESULTS: With the increase of slice thickness, the staining of p16 protein in nucleus gradually increased. The thickness of cervical slices in chronic cervicitis and cervical cancer samples had no significant effect on the positive rate of p16 protein(=7.817 and 1.332, both >0.05), while the thickness of slices in LSIL and HSIL samples had significant effect on the positive rate of p16 protein (=17.688 and 10.182, <0.05 or <0.01). The stable and reliable results were obtained when the slices were between 3 and 5 μm thick. CONCLUSIONS Paraffin sections with thickness of 3.0-5.0 μm are recommended for immnohistochemical staining of p16 protein in cervical tissue samples.
Biomarkers, Tumor ; genetics ; metabolism ; Cervical Intraepithelial Neoplasia ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Female ; Histocytological Preparation Techniques ; standards ; Humans ; Immunohistochemistry ; Paraffin ; Squamous Intraepithelial Lesions of the Cervix ; Uterine Cervical Neoplasms ; physiopathology

OBJECTIVETo study the role of p16 gene mutation status as detected by fluorescence in-situ hybridization (FISH) and p16 protein expression as detected by immunohistochemistry in differential diagnosis of malignant mesothelioma and benign mesothelial hyperplasia.

METHODSp16 gene mutation status and protein expression were detected by FISH and immunohistochemistry respectively in 55 cases of pleural malignant mesothelioma and 30 cases of benign mesothelial hyperplasia.

RESULTSFISH study showed that the rate of p16 deletion in malignant mesothelioma (81.8%,45/55) was higher than that in benign mesothelial hyperplasia (3.3%,1/30). The difference was statistically significant (P<0.05). Immunohistochemical study showed that the rate of p16 protein expression in malignant mesothelioma (23.6%) was lower than that in benign mesothelial hyperplasia (76.7%). The difference was also statistically significant. The sensitivity and specificity of FISH in distinguishing between mesothelioma and reactive mesothelial hyperplasia were higher than those of immunohistochemistry.

CONCLUSIONSIn contrast to reactive mesothelial hyperplasia, p16 gene is deleted and p16 protein is not expressed in malignant mesothelioma. The sensitivity and specificity of FISH are higher than those of immunohistochemistry in the distinction.

Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Diagnosis, Differential ; Epithelium ; pathology ; Genes, p16 ; Humans ; Hyperplasia ; diagnosis ; genetics ; Immunohistochemistry ; In Situ Hybridization, Fluorescence ; Mesothelioma ; diagnosis ; genetics ; metabolism ; Mutation ; Pleura ; pathology ; Pleural Neoplasms ; diagnosis ; genetics ; metabolism ; Sensitivity and Specificity

OBJECTIVETo investigate the expression level of COX-2, p16(INK4A) and p53 in patients with classic Hodgkin's lymphoma (cHL), and to evaluate their correlation with prognosis.

METHODSThe clinical data and samples of 52 cHL cases were collected. Immunohistochemical staining was performed to analyze the proteins level mentioned above and in situ hybridization of EBV encoded RNA (EBER) to clarify the tumor EBV infection state. Correlation between the protein expression and prognosis of patients was analyzed.

RESULTSOf 52 cases, the male and female ratio was 1.6∶1, the age was from 22 to 68 years old. All lesions located primarily in lymph nodes. All samples from 52 cases were stained with COX-2, p16(INK4A) and p53, and the positive expression of COX-2 was found in 28 cases (53.8%）, that of p16(INK4A) in 25 cases (48.1%)and p53 in 42 cases (80.8%）. All patients were divided into two groups according to differences in age (<40 years/ ≥ 40 years), gender (male/female), EBV infection (yes/no), B symptoms (yes/no), and the Ann Arbor staging (Ⅰ-Ⅱ/Ⅲ-Ⅳ), the correlation with COX-2, p16(INK4A) and p53 expression were analyzed, and only p53 expression was correlated with Ann Arbor staging (P=0.027). The statistical analysis of correlations between COX- 2, p16(INK4A) and p53 showed that the expression of COX-2 was strongly correlated with p53 (P=0.008), and p16 (INK4A) was not related to either COX-2 or p53 (P=0.246 and 0.958). Kaplan- Meier univariate OS analysis using SPSS17.0 software showed that only COX-2 expression was an adverse prognostic factor for patients'event free survival (EFS) (P=0.003). Meanwhile COX-2 expression was a unique independent prognostic factor analyzed by COX proportional hazards regression model (HR=0.091, 95% CI 0.017-0.505, P=0.006).

CONCLUSIONThe expression rate of COX-2, p16 (INK4A) and p53 in the cHL were relatively high; and they were not statistically correlated with tumor EBV infection status; the COX-2 positive group had poor prognosis, but only event free survival time becomes statistically significant shorter. COX proportional hazard regression model was used to analyze the COX-2 expression as a independent adverse prognostic factors for EFS.

Adult ; Aged ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Cyclooxygenase 2 ; genetics ; metabolism ; Disease-Free Survival ; Epstein-Barr Virus Infections ; Female ; Hodgkin Disease ; diagnosis ; genetics ; metabolism ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Male ; Middle Aged ; Prognosis ; Proportional Hazards Models ; Tumor Suppressor Protein p53 ; genetics ; metabolism ; Young Adult

OBJECTIVE: To investigate the effect of gene silencing of Bmi-1 on proliferation regulation of CD44+ nasopharyngeal carcinoma cancer stem-like cells (CSC-LCs). METHOD: The sequence-specific short hairpin RNA lentivirus targeting at human Bmi-1 gene (LV-Bmi-1shRNA) was constructed and was used to infect CD44+ nasopharyngeal carcinoma cells which were sorted by flow cytometry. A lentiviral which included a random sequence was also designed to serve as a negative control. We employed fluorescence microscope and flow cytometry to detect infection efficiency; real-time PCR was used to detect Bmi-1 and its downstream gene while each protein expression level was confirmed by western blotting protocol; CCK-8 proliferation assay was applied to measure proliferation capacity; tumor spheroid assay was used to evaluate the self-renewal capacity. Colony formation assay was used to measure cell colony formation capability; flow cytometry analyzed cell cycle distribution. RESULT: The constructed LV-Bmi-1shRNA successfully infected into the CD44+ nasopharyngeal carcinoma cells. The infection efficiency could reach above 95%; LV-Bmi-lshRNA effectively inhibited Bmi-1 mRNA and protein expression, while the downstream gene p16INK4a and p14ARF mRNA as well as protein expression level were upregulated (P < 0.05). Notablely, the proliferation, colony formation, self-renewal capabilities of the experimental group decreased significantly (P < 0.05). In addition, the cell cycle arrested at the G0-G1 phase. CONCLUSION Gene silencing of Bmi-1 inhibited the proliferation, colony formation and self-renewal capabilities of the CD44+ nasopharyngeal carcinoma CSC-LCs, inhibited the cell cycle processes, which may mediate through Bmi1-p16INK4a/p14ARF-p53 pathway. Our experimental results indicated that Bmi-1 gene may play an important role in the maintenance of the stem cell-like characteristics of CD44+ nasopharyngeal carcinoma cells. Bmi-1 gene may be a potential new target for the treatment of nasopharyng al carcinoma in the future.
Carcinoma ; Cell Cycle ; Cell Division ; Cell Line, Tumor ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Gene Silencing ; Humans ; Hyaluronan Receptors ; metabolism ; Lentivirus ; Nasopharyngeal Carcinoma ; Nasopharyngeal Neoplasms ; genetics ; pathology ; Neoplastic Stem Cells ; cytology ; Polycomb Repressive Complex 1 ; genetics ; RNA, Messenger ; RNA, Small Interfering ; Tumor Suppressor Protein p14ARF ; metabolism ; Tumor Suppressor Protein p53 ; metabolism

The latest findings of our laboratory showed that Angelica sinensis polysaccharide (ASP) showed a definite effect in regulating the aging of hematopoietic stem cells. Leukemia is a type of malignant hematopoietic tumor in hematopoietic stem cells. There have been no relevant reports about ASP's effect in regulating the aging of leukemia cells. In this study, human acute myeloid leukemia (AML) KG1alpha cell lines in logarithmic growth phase were taken as the study object, and were divided into the ASP group, the cytarabine (Ara-C) group, the ASP + Ara-C group and the control group. The groups were respectively treated with different concentration of ASP, Ara-C and ASP + Ara-C for different periods, with the aim to study the effect of ASP combined with Ara-C in regulating the aging of human acute myeloid leukemia KG1alpha cell lines and its relevant mechanism. The results showed that ASP, Ara-C and ASP + Ara-C could obviously inhibit KG1alpha cell proliferation in vitro, block the cells in G0/G1 phase. The cells showed the aging morphological feature. The percentage of positive stained aging cells was dramatically increased, and could significantly up-regulate the expression of aging-related proteins P16 and RB, which were more obvious in the ASP + Ara-C group. In conclusion, the aging mechanism of KG1alpha cell induced by ASP and Ara-C may be related to the regulation of the expression of aging-related proteins, suggesting that the combined administration of ASP and anticancer drugs plays a better role in the treatment of leukemia .
Aging ; drug effects ; genetics ; metabolism ; Angelica sinensis ; chemistry ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Humans ; Leukemia ; drug therapy ; genetics ; metabolism ; physiopathology ; Polysaccharides ; pharmacology ; Retinoblastoma Protein ; genetics ; metabolism ; Tumor Cells, Cultured

OBJECTIVETo explore the proliferation and invasive effects of inhibitors of kinase 4(INK4)(P15(ink4b) and P16(ink4a)/CDKN2) gene protein activation on RKO human colorectal cell in vivo and in vitro.

METHODSRKO human colorectal cell line was exposed to the specific DNA methyltransferase inhibitor 5-Aza-CdR and INK4(P15(ink4b) and P16(ink4a)/CDKN2) protein expression was detected by Western blotting. Soft agar cloning experiment and Transwell chamber assay were used to detect the proliferative and invasive ability in vitro. Tumorigenicity in nude mice was analyzed in vivo.

RESULTSINK4(P15(ink4b) and P16(ink4a)/CDKN2) protein expression of RKO human colorectal cells after exposure to 1×10(-7), 5×10(-7) and 1×10(-6) mol/L 5-Aza-CdR concentrations(A, B, C groups) were 1.13, 1.38, 1.92 folds and 1.11, 1.45, 2.14 folds compared to positive control group respectively. Soft agar cloning experiment showed the number of cell colony significantly decreased from 36.8±5.1(positive control group) to 32.4±7.2, 21.3±5.4 and 19.5±6.4 (3 experiment groups, all P<0.05) respectively. Transwell chamber assay showed that migrated cell number in positive control group(67.4±7.2) was significantly higher than those of 3 experimental groups(35.3±4.6, 29.5±7.3 and 25.3±6.2, respectively). The tumor volume of metastasis model in nude mice was inhibited in experimental groups, but not significantly lower compared to control group (P>0.05). There were significant differences of tumor weight and inhibition rate between control group and 3 experimental groups in nude mice respectively(all P<0.01).

CONCLUSIONINK4(P15(ink4b) and P16(ink4a)/CDKN2) protein activation can inhibit tumor proliferation, migration and suppress the tumor formation ability.

Animals ; Cell Line, Tumor ; Cell Proliferation ; Colorectal Neoplasms ; metabolism ; pathology ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Humans ; Mice ; Mice, Inbred BALB C ; Neoplasm Metastasis ; Neoplasm Transplantation ; Transcriptional Activation

OBJECTIVEThe effect of angelica sinensis polysaccharides (ASP) on the production of reactive oxygen specie (ROS), the capability of total anti-oxidant (T-AOC), and the expression of p16 in mRNA level in mice hematopoietic stem cells (HSCs) were observed to explore the underlying mechanism that ASP delay aging of HSCs in vivo.

METHODC57BL/6J mice were randomly divided into normal group, aging group, and the above groups treated with ASP. Mice were uniformly explored in X-ray (3.0 Gy/8 F) to erect model of aging. Normal and aging ASP intervention groups mice were treated with ASP by intragastric administration, while normal and aging groups were treated with equal-volume NS during X-ray irradiation. Mice HSCs were isolated by magnetic cell sorting and cultured in vitro. Senescence-associated beta-galactosidase (SA-beta-Gal) staining was used to detect aging HSCs. Cell cycles analysis and CFU-Mix cultivation were used to evaluate the capability of self-renewing and colony forming in HSCs. The production of ROS in HSCs was evaluated by flow cytometry analysis and immunofluorescence assess, respectively. T-AOC was detected by chemical colorimetric method. The expression of p16 was determined by real-time quantitative PCR (qRT-PCR).

RESULTExogenous X-ray irradiation induced HSCs aging was compared with normal group without irradiation. Biological feature of HSCs in aging group with X-ray irradiation as follows: The percentage of SA-beta-Gal positive cells, the ratio of G1 stages and the production of ROS were significantly increased , the expression of p16 in mRNA level was also upregulated. The capacility of colony forming and T-AOC in HSCs were decreased. ASP could significantly decrease the percentage of SA-beta-Gal positive cells, the ratio of G1 stages and the production of ROS in HSCs, and downregulate the expression of p16 in mRNA level in HSCs contrast to aging group without ASP treatment. In addition, ASP could remarkably increase T-AOC and the capacility of colony forming in HSCs compared with aging group without ASP treatment.

CONCLUSIONX-ray (3.0 Gy/8 F) could induce mice HSCs aging. ASP could delay senescence HSCs aging which maybe partly ascribed to the inhibition of oxidative damage and the downregulation of p16 mRNA expression.

Aging ; drug effects ; radiation effects ; Angelica sinensis ; chemistry ; Animals ; Cell Cycle ; drug effects ; radiation effects ; Cells, Cultured ; Cellular Senescence ; drug effects ; radiation effects ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; Female ; Flow Cytometry ; Gene Expression ; drug effects ; radiation effects ; Hematopoietic Stem Cells ; drug effects ; metabolism ; radiation effects ; Male ; Mice ; Mice, Inbred C57BL ; Oxidative Stress ; drug effects ; radiation effects ; Polysaccharides ; pharmacology ; Random Allocation ; Reactive Oxygen Species ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Time Factors ; X-Rays ; beta-Galactosidase ; metabolism

OBJECTIVETo investigate the relationship between HPV-DNA status and p16 protein expression in oropharyngeal squamous cell carcinoma (OSCC) and their clinical significance.

METHODSSixty-six patients with oropharyngeal squamous cell carcinomas treated in the Cancer Hospital of Chinese Academy of Medical Sciences from Jan. 1999 to Dec. 2009 were included in this study. Their formalin-fixed and paraffin-embedded tumor tissue blocks met the eligibility criteria and were used in this study. A "sandwich" technique was used to prepare paraffin sections for HPV-DNA analysis. HPV-DNA was detected using the SPF10 LiPA25 version 1 assay. The expression of p16 protein was detected by immunohistochemistry. The survival rates of patients with different HPV-DNA and p16 protein status were analyzed.

RESULTSHPV-DNA was detected in 11 (16.7%) of all specimens. Expression of p16 protein was detected in 9 of the 11 patients with HPV-positive tumors, and in 12 patients of 55 HPV-negative tumors. The expression of p16 protein was highly correlated with the presence of HPV-DNA (P < 0.001). The tumors were classified into three groups based on the p16 protein expression and HPV-DNA status: group A (9 patients): HPV(+) and p16 protein(+); group B (14 patients): HPV-DNA(+)/p16 protein(-) or HPV-DNA(-)/p16 protein(+); and group C (43 patients): HPV-DNA(-)/p16 protein(-). The 3-year OS rates of these 3 groups were 100%, 77.8% and 42.0% (P = 0.001), and their DSS rates were 100%, 77.8% and 46.4%, respectively(P = 0.004).

CONCLUSIONSIn oropharyngeal squamous cell carcinomas, p16 protein expression is highly correlated with the presence of HPV-DNA, and might be a surrogate marker for HPV-positive OSCC. Combination of p16 protein and HPV-DNA status detection may help to more accurately stratify oropharyngeal carcinomas and predict their prognosis.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; genetics ; metabolism ; virology ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; DNA, Viral ; isolation & purification ; Female ; Follow-Up Studies ; Humans ; Male ; Middle Aged ; Neoplasm Metastasis ; Neoplasm Recurrence, Local ; Oropharyngeal Neoplasms ; genetics ; metabolism ; virology ; Papillomaviridae ; Papillomavirus Infections ; genetics ; metabolism ; Survival Rate

OBJECTIVETo investigate the effects and related mechanisms of hepatitis B virus X (HBx) protein on cell cycle and growth in hepatocellular carcinoma.

METHODSA human hepatocyte HepG2 cell line stably expressing a green fluorescent protein (GFP)-tagged HBx (HepG2/GFP-HBx cells) was used for the experiment, and HepG2 parental and HepG2/GFP cells was used as the controls. Effect of HBx on cell growth was evaluated by the MTT cell proliferation assay and on cell cycle progression by flow cytometry analysis of cells with or without treatment with 5-aza-2'-deoxycytidine (5-Aza-CdR; 5 pmol/L). Effect of HBx expression on promoter methylation status of the p16INK4A tumor-suppressor gene was detected by methylation-specific polymerase chain reaction and on p16 protein level was analyzed with western blotting.

RESULTSThe HepG2/GFP-HBx cells showed significantly higher cell proliferation at 72 hrs of culture (3.225+/-0.038 A490) than either control (HepG2: 2.012+/-0.022 A490, t = -46.86, P less than 0.001; HepG2/GFP: 2.038+/-0.029 A490, t = 42.51, P less than 0.001). The HepG2/GFP-HBx cells also showed significantly lower proportion of cells in the G0/G1 phase (16.45%+/-0.45%) than either control (HepG2: 44.81%+/-1.36%, t = -34.202, P less than 0.001; HepG2/GFP: 42.76%+/-1.58%, t = -28.88, P less than 0.001). However, 5-Aza-CdR treatment did lead to a significant amount of HepG2/GFP-HBx cells being arrested in the G0/G1 phase (33.25%+/-0.79%, t = 31.85, P less than 0.001). The p16INK4A promoter was methylated in the HepG2/GFP-HBx cells, and became demethylation after treatment with 5-Aza-CdR. However, no methylation of p16INK4A promoter was observed in both HepG2 and HepG2/GFP cells. The p16 protein level was significantly lower in the HepG2/GFP-HBx (vs. HepG2 and HepG2/GFP cells) and this level increased after treatment with 5-Aza-CdR.

CONCLUSIONHBx protein promotes hepatocellular carcinoma cell cycle progression and growth by shortening the G0/G1 phase, and the underlying mechanism may involve inducing p16INK4A promoter methylation and downregulating p16 protein expression.

Carcinoma, Hepatocellular ; metabolism ; pathology ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Gene Expression Regulation, Neoplastic ; Genes, p16 ; Hep G2 Cells ; Hepatitis B virus ; metabolism ; Humans ; Liver Neoplasms ; metabolism ; pathology ; Promoter Regions, Genetic ; Trans-Activators ; pharmacology