Tumor suppressor gene p16 and Rb expression in gastric cardia precancerouslesions from subjects at a high incidence area in northern China

AIM:To further understand the molecular basis for gastric cardia carcinogenesis and to provide etiological clues. METHODS: Endoscopic mucosa biopsy and histopathological examinations were made on 37 subjects from a high incidence area for both esophageal and gastric cardia carcinomas in northern China. All the biopsy samples were fixed in 850 ml. (-1)L alcohol and embedded in paraffin. Each block contained one piece of tissue and was serially section at 5 microm. Immunohistochemistry (ABC) was carried out on these gastric cardia samples to determine the alterations of p16 and Rb. RESULTS: Based on the histopathlogical examination there were 11 cases of chronic superficial gastritis, 12 cases of chronic atrophic gastritis and 14 cases of dysplasia. The immunostaining demonstrated different levels of unclear immunostaining of p16 and Rb in normal gastric cardia tissue and the tissues with different severity of lesions. With the lesions progressing, the positive immunostaining rates for p16 protein had a decreasing tendency. In contrast, the positive immunostaining rate for Rb protein had an increasing tendency. There was a significant negative relationship between the two parameters. Changes of p16 was CSG 11(100%), CAG 7(58%), DYS 4(29%) and changes of Rb was CSG 2(18%), CAG 8(67%) and DYS 12(86%), (P【0.05). CONCLUSION: The alterations of p16 and Rb protein may play a role in the early stages of gastric cardia carcinogenesis.

PROMOTER HYPERMETHYLATION OF p16 GENE AND DAPK GENE IN SERA FROM HEPATOCELLULAR CARCINOMA (HCC) PATIENTS

Objective： To analyze the aberrant methylation of p16 gene and DAPK gene in sera from primary liver cancer patients ad to evaluate the clinical significance. Methods： A methylation-specific PCR was performed for the detection of promoter hypermethylation of p16 gene and DAPK gene in blood DNA from 64 cases of HCC patients, and to analyze the relation of the aberrant methylation of p16 gene and KAPK gene and the clinical pathological data. Results： 76.6%（49/64） of the sera from 64 cases of HCC patients showed hypermethylation for p16 promoter and 40.6% （26/64） for KAPK promoter, whereas no methylated p16 gene promoter and DAPK gene promoter were found in sera from benign liver diseases patients and normal control. Methylated p16 gene and KAPK gene promoters in sera did not strongly correlated with HBsAg, stage, metastasis and differentiation in HCC; but strongly correlated with AFP. Conclusion： Detection of the aberrant methylation of p16 gene and KAPK gene in blood DNA from HCC patients might offer an effective means for the earlier auxiliary diagnosis of the malignancy.

FREQUENT DELETION OF MTS1/p16 GENE AND CORRELATION WITH CLINICOPATHOLOGICAL PARAMETERS IN ENDOMETRIAL CARCINOMA

Objective: To investigate the possible relationship between deletion of MTS/p16 gene and progression of endometrial carcinoma Methods: Forty six primary endometrial carcinoma, 7 tumor adjacent endometrial tissue, 10 normal endometrial tissue specimen and 5 xenografts from patients with endometrial carcinoma were examined for homozygous deletion of MTS/p16 gene by polymerase chain reaction based analysis Results: Of 46 endometrial cancer specimens, 9 showed homozygous deletion, no deletion was detected in the tumor adjacent and normal endometial tissues Nor was it detected in well differentiated endometrial carcinoma and all xenografts Conclusions: Deletion of MTS1/p16 gene might contribute to the progression of endometrial carcinoma and could be served as indicator for predicting prognosis

Exogenous p16 gene therapy combined with X-ray irradiation suppresses the growth of human glioma cells

In this study, we infected human glioma U251 cells with a replication-defective recombinant adenovirus carrying the p16 gene. This adenovirus constructed was able to transfect exogenous p16 into the human glioma cells efficiently, and direct a high level of p16 protein expression. Tumor-inhibition experiments demonstrated that treatment with the adenovirus-p16 significantly inhibited the growth of glioma cells in vitro as well as the in vivo development of tumors in nude mice bearing a brain glioma. The combination of adenovirus-p16 gene treatment and X-ray irradiation resulted in a greater inhibition of tumor growth. Adenovirus-mediated p16 gene therapy conferred a significant antitumor effect against human glioma cells both in vitro and in vivo, and that there was a synergistic effect when X-ray irradiation was also used.

p16 gene methylation in colorectal cancers associated with Duke's staging

AIM: To explore the association of methylation of the CpG island in the promotor of the p16 tumor suppressor gene with the clinicopathological characteristics of the colorectal cancers. METHODS: Methylation-specific PCR (MSP) was used to detect p16 methylation of 62 sporadic colorectal cancer specimens. RESULTS: p16 methylation was detected in 42% of the tumors.Dukes'staging was associated with p16 methylation status.p16 methylation occurred more frequently in Dukes'C and D patients (75.9%) than in Dukes'A and B patients (12.1%). CONCLUSION: p16 methylation plays a role in the carcinogenesis of a subset of colorectal cancer, and it might be linked to poor prognosis.

Effect of 5-Aza-2'-deoxycytidine on the P16 tumor suppressor gene in hepatocellular carcinoma cell line HepG2

INTRODUCTIONHepatocellular carcinoma (HCC) is one of the mostcommon human malignancies worldwide[1,2], and isclosely associated with infection of HBV and HCVand contamination of aflatoxin B1[3-6]. Althoughthe molecular mechanisms of hepatocarcinogenesisremain poorly understood, an increasing number ofgenetic abnormalities have been recognized[7-10],for example, the p16 gene[11,12] the p53gene[13-18], the E-cadherin gene[19], and the c-mycgene[20].

Quantitative Study on Expression of P16 Multiple Tumor Suppressor Gene in Salivary Gland Neoplasm

The expression of P16 gene were found in all 3 groups. The positive unit (PU) was higher in tumor group and cancer group than that in normal group ( P <0.01). Furthermore, the PU of P16 was stronger in cytoplasm than in nucleus. Malignant tumors and acini surrounding the tumor revealed strong positives and week positives respectively. The PU of P16 gene was higher in deep lobe of recurrent parotid neoplasm with incomplete capsule than that in shallow lobe of primary parotid neoplasm with complete capsule. Our findings suggests that P16 gene plays equally important role in the salivary gland tumors and tumors in other part of the body.

Effects of Exogenous p16^(ink4a) Gene on Biological Behaviors of Human Lung Cancer Cells

The effects of exogenous p16^ink4a gene on biological behaviors of human lung cancer cell line with homozygous deletion of p16^ink4a gene were investigated. Exogenous p16^ink4a gene was transfected by lipofectin into human lung cell line A549, in which p16^ink4a gene was homozygously deleted. The expression of p16^ink4a mRNA and protein was detected by RT-PCR and immunocytochemistry, respectively. The changes in the behaviors of the transfected cell lines in vitro and in vivo were observed. In the transfected cell line A549, the exogenous p16^ink4a gene could be stably expressed. The growth of A549 cells transfected with p16^ink4a gene was obviously slowed down. Flow cytometry revealed that transfection of the exogenous p16^ink4a gene resulted in A549 cell lines arrest in G1 phase of cell cycle. The tumorigenicity of these transfected cells in nude mice could be inhibited, and the tumor growth of nude mice was significantly suppressed. It was concluded that exogenous p16^ink4a gene may be stably expressed in human lung cancer cell line A549. The expression of the introduced p16^ink4a could block lung cancer cells to entry into S phase of cell cycle and inhibit tumor malignant growth both in vitro and in vivo.

Gene Product Expression of Cyclin D_2 and p16 During the Transition from Cardiac Myocyte Hyperplasia to Hypertrophy

The current study was to investigate mRNA expression of cyclin D 2 and p16 during the transition from cardiac myocyte hyperplasia to hypertrophy. Cultured cardiac myocytes (CM) and fibroblasts (FC) obtained from 1 day old Sparague Dawley rats were used in this study. We have determined (1) hyperplasia by cell growth curve and fluorescence activated cell sorting (FACS); and (2) ultrastructure by electron microscope observation; and (3) expressions of cyclin D 2 mRNA and p16 mRNA by using in situ hybridization and image analysis. The results were shown (1) Results of cell growth curve and FACS analysis showed CM could proliferate in the first 3 cultured days (4 days in postnatal development). But the ability decreased quickly, concomitant with the differentiation. (2) The ultrastructure of CM showed the large amount of myofilaments and mitochondrion and FC showed moderate amount of rough endoplasmic reticulum. (3) The expression of cyclin D 2 mRNA in 3 , 4 , 5 day CM group was 0.89 times(p<0.05), 0.80 times (p<0.05)and 0.56 times (p<0.01)of that in 1 day group respectively. P16 mRNA in 2 , 3 , 4 , 5 day CM group were 1.63 times(p<0.01),1.72 times(p<0.01),1.99 times (p<0.01)and 2.84 times (p<0.01) of that in 1 day group respectively. It can be concluded that cultured neonatal rat cardiac myocytes could proliferate during the first 3 cultured days, but the ability of proliferation decreased, from the fourth day, concomitant with differentiation. Cyclin D 2 and p16 have the key roles during the transition from myocyte hyperplasia to hypertrophy.

STUDY OF DELETION OF P16 GENE IN THE PROGRESSION OF BRAIN ASTROCYTOMAS

Objective: To study the relationship between deletion of P16 gene and occurrence and progression of astrocytomas Methods: The techniques of polymerase chain reaction (PCR) and immunohistochemistry were used to detect the deletion of exon2 of P16 gene and expression of P16 gene in 52 cases of Brain astrocytoma Results: The deletion rate of exon2 of P16 gene in the tumors analyzed was 34 6% Most of them with deletion of exon2 of p16 gene were high grade astrocytomas (grade III 42%, grade IV 50%) 61 5% of the tumors were absent from expression of p16 and the deletion rate of p16 protein increased with the grade of astrocytoma (X 2=10 83, P <0 005) Conclusion: Deletion of p16 gene and protein may correlate with the malignant progression of astrocytoma

EFFECTS OF p16^(INK4) GENE ON CHEMOSENSITIVITY OF HUMAN GLIOMA U251 CELL LINE TO TENIPOSIDE

Objective: To determine the effects on the cell growth, tumorigenicity and chemosensitivity of p16/CDK4I in human glioma. Methods: p16 gene was transfected into U251 cells by lipofectin. Expression of exogenous p16 gene was confirmed by immunohistochemistry and Northern blot. The effects of exogenous p16 gene on the growth and chemosensitivity to teniposide were examined. Results: Expression of exogenous p16 gene inhibited the growth dramatically in vitro. G1 arrest of tumor cells was observed. However, wt p16-positive U251 was less sensitive than control cell lines and the number of apoptotic cells after chemotherapy was reduced. Conclusion: The expression of exogenous p16 gene could inhibit the growth of glioma. On the other hand, the chemosensitivity to teniposide of p16-positive U251 was decreased.

PROMOTER HYPERMETHYLATION OF p16 GENE IN PRE- AND POST-OPERATIVE PLASMA OF PATIENTS WITH GASTRIC ADENOCARCINOMA

Objective: To detect promoter hypermethylation of p16 gene in matched pre- and post-operative plasma of patients with gastric adenocarcinoma for evaluating the effectiveness of therapeutic intervention. Methods: Tissue samples, pre- and post-operative plasma of 84 patients were collected. Plasma of 15 healthy people was collected as control. After sodium-bisulfite treatment, extracted DNA was amplified for p16 promoter by methylation-specific polymerase chain reaction (MSP). The PCR products were detected by both gel-ethidium bromide electrophoresis and high performance liquid chromatogram (HPLC). Results: Among 84 patients, p16 hypermethylation was detected in 26 (31.0%) cancer tissues and 2 (0.02%) tumor-adjacent tissues and 12 (14.3%) pre-operative plasma, while negative in plasma of healthy people. For positive plasma cases, the paired tumor tissues were confirmed to be methylated. Within available 30 pairs of matched pre- and post-operative plasma, 6 pre-operative plasma was positive, and only 1 of 6 plasma remained hypermethylated after surgery. The results detected by HPLC exactly matched those by gel-electrophoresis. Conclusion: The alteration of status of p16 hypermethylation in post-operative plasma is considered the consequences of surgical intervention. Although p16 hypermethylation has no role in pre-operative staging of gastric cancer, detecting hypermethylated p16 in plasma could be utilized in monitoring patients after surgery.

IN SITU PCR AND IMMUNOHISTOCHEMICAL STUDIES ON p16 GENE IN PITUITARY ADENOMAS

Objective: To examine the occurrence of p16 gene deletion and to analyze p16 expression on paraffin-embedded human pituitary adenoma specimens. Efforts were made to optimize the technical conditions forin situ PCR. Methods:In situ PCR techniques and inimuno-histochemistry were used. Results: Immunohistochemically, p16-positive tumor cells were observed in all cases with various proportions. The majority of the stromal cells and part of tumor cells was devoid of p16 immunostaining, but signal ofin situ PCR for p16 gene, exon 2, was displayed in these cells. Conclusion: The results implied that p16 gene might not be deleted in these pituitary adenomas. It also indicated thatin situ PCR, both direct and indirect methods, proved feasible and informative to the aim of DNA detection. It is critical to overcome non-specific amplification in directin situ PCR by means of higher annealing temperature, fewer cycle, lower magnesium concentration and stringent washing. A target DNA-deleted sample as the negative control is extremely necessary. For the indirect method, the way to improve the sensitivity is to loosen the conditions for amplification and washing, so that more amplification products are subject to hybridization, and signal detection is facilitated.

Study on P16 Gene in Acute Leukemia

To stddy the chang of suppressing cancer gene P16 in acute leukemia, the P16 antigen expression of leukemia cell surfaces in 61 cases were investigated with ABC assay and gene structural defects in 51 cases of acute leukemia were examined with multiple comparative PCR method. It was found that antigen expression of P16 in leukemia was obviously lower than that innormal subjects ( P <0 001). At the same time, antigen expression in All was lower than that AML ( P <0 05). No significant difference was found betwee the complete reission (CR) and non remission (NR) subjects from AML and ALL groups ( P >0 05). THe exon 2 of P16 gene showed homozygous deletion only inn4 cases out of 30 cases in ALL. No stuctural defect was revealed in 21 cases of AML. It was suggested that expression defect of P16 gene was a main cause in development and progression of acute leukemia, and structural defect of exon 2 was not a primary molecular event.

Expression and significance of tumor suppressor gene p16 in human ovarian neoplasm

To observe the relationship between tumor suppressor gene p16 expression and ovarian cancer occurrence and development. Metbods: Using ABC immunohistochemistry method, we investigated the expression of p16 in 72 cases of ovarian neoplasm. Results: The positive rates of p16 in malignant, benign, borderline tumors and normal ovarian tissue were 7. 89%, 60.00%, 66. 67% and 83. 33%, respectively (P<0.01). In the cases whose tumors were more malignant and poorly differentiated, and who relapsed and died, the positive stainings were not discovered. Conclusiou: p16 is well related with the occurrence and development of malignant ovarian tumor.

温石棉对内皮细胞Wnt5a、p16和p21表达的影响

目的探讨温石棉对人脐静脉内皮细胞(HUVECs)的影响。方法实验组以50、100、200 mg/L温石棉纤维液刺激HUVECs 24、48、72 h,对照组仅加RPMI 1640培养基培养细胞,观察细胞形态变化,β-半乳糖苷酶法分析细胞衰老情况,四甲基偶氮唑蓝法检测细胞存活率。采用实时荧光定量PCR法检测细胞中Wnt5a、p16和p21 mRNA的表达情况。结果实验组HUVECs多呈梭形,部分呈圆形或不规则形,出现裸核及空泡现象,可见死亡细胞。随温石棉质量浓度及暴露时间的增加,细胞活性逐渐降低,衰老细胞逐渐增多。100 mg/L温石棉处理HUVECs 24 h时,细胞生长较活跃。与对照组相比,实验组Wnt5a、p16和p21 mRNA表达水平均增高(P<0.05)。结论温石棉可促进HUVECs衰老,Wnt5a、p16和p21参与此过程。

P53、P16及Ki-67与早期食管癌患者ESD术后复发的关系分析

目的 分析研究抑制蛋白基因P53(P53)、抑制蛋白基因P16(P16)及细胞增殖核抗原Ki-67(Ki-67)与早期食管癌患者内镜黏膜下剥离术(ESD)术后复发的关系。方法 选取2019年1月至2023年1月三门峡市中心医院收治80例的早期食管癌患者作为研究对象,均进行ESD治疗。比较所有患者癌组织与癌旁组织(距肿瘤边缘>3 cm,镜下未见肿瘤组织或不典型增生组织)P53、P16、Ki-67蛋白表达。ESD术后对患者随访1年,根据有无术后复发食管癌,将患者分为复发组(n=20)与无复发组(n=60)。比较两组癌组织P53、P16、Ki-67蛋白表达。采用多因素Logistic回归分析早期食管癌患者ESD术后复发的影响因素,并绘制ROC曲线分析P53、P16、Ki-67蛋白表达与早期食管癌患者ESD术后复发。结果 与癌旁组织相比,癌组织P53、Ki-67蛋白表达升高,P16蛋白表达降低(t=9.276、13.987、10.595,均P<0.05);复发组的癌组织P53、Ki-67蛋白表达均高于无复发组,P16蛋白表达低于无复发组(t=5.086、4.648、5.139,均P<0.05);多因素Logistic回归分析显示,肿瘤低分化(OR=1.870)、肿瘤浸润侵犯黏膜下层(OR=1.808)、有淋巴结转移(OR=2.089)、P53蛋白高表达(OR=2.046)、P16蛋白低表达(OR=1.988)及Ki-67蛋白高表达(OR=1.761)均是早期食管癌患者ESD术后复发的独立危险因素(P<0.05);ROC曲线分析显示,P53、P16、Ki-67蛋白表达及联合检测的曲线下面积(AUC)分别为0.803、0.828、0.834、0.942,联合检测优于单一检测(P<0.05)。结论 P53、P16及Ki-67蛋白与早期食管癌患者ESD术后复发情况相关,可以作为辅助预测的相关诊断指标。

基于p16/ki67细胞学双染检测宫颈癌前病变的研究

目的探讨p16/ki67细胞学双染检测在宫颈病变筛查中的应用价值。方法收集妇科宫颈病变门诊患者56例为研究对象,所有患者均行宫颈液基细胞学检查(TCT)、人乳头瘤状病毒(HPV)检测、阴道镜活检,并进行p16/ki67双染,分析比较双染与TCT、HPV检查诊断宫颈病变的效能,并研究p16/ki67双染诊断宫颈病变的价值。结果在细胞学为非侵入式负荷监测(NILM)、不典型鳞状细胞(ASC-US)、低级别鳞状上皮内病变(LSIL)以上病变的分级患者中p16/ki67双染阳性的比例分别是15.38%、66.67%、92%,不同宫颈组织学诊断结果中慢性宫颈炎、宫颈上皮内瘤变Ⅰ级(CINⅠ)、宫颈上皮内瘤变Ⅱ级(CINⅡ)和Ⅲ级(CINⅢ)的患者中p16/ki67双染阳性率分别为6.66%、75%、78.57%、100%,总体差异有统计学意义(P<0.05)。结论p16/ki67免疫细胞化学染色阳性率与宫颈癌前期病变的严重程度呈现正相关。P16/ki67双染较TCT和HPV提高了宫颈病变筛查的灵敏性和特异性,并提高了高级别鳞状上皮内病变(HSIL)的检出率,减少阴道镜的转诊率,值得应用于临床。

Wilms瘤p16基因的表达

目的 探讨p16基因表达产物 p16在Wilms瘤中的表达及其与病理分型和临床分期间的关系。方法 应用免疫组织化学S -P方法常规进行染色。结果 5 2例Wilms瘤中 ,p16表达阳性在预后好的病理分型和预后差的病理分型分别为 37.2 %、0 % ,两组差异显著 (P <0 .0 5 )。p16阳性表达在Ⅰ、Ⅱ、Ⅲ、Ⅳ期分别为 91%、6 0 %、40 %、6 .6 7%。 4期间比较 ,差异显著 (P <0 .0 5 )。结论 p16蛋白表达与病理分型及临床分期有关 。