Abnormal Change of p53 Gene in Gastric and PrecancerousLesions and APC Gene Deletion in Gastric Carcinoma and Near Tissues

p53 gene mutation (exon4, 5, 6, 7, 8 and intron6) in gastric cancer and precancerous lesions and p53 gene (exon4 and ontron6), APC gene deletion in gastric carcinomas were studied by PCR/SSCP and PCR/RFLP- Results showed mutation rate of p53 in metaplasia, dysplasia and gastric carcinoma was 37. 5 % (3/8), 42. 11 % (8/19), 53. 33 (16/30) respectively- There was significant dif-ference among groups of metaplasia, dysplasia, cancer and normal controls. Noexon8 mutation was found in metaplasia and dysplasia, but 4 cases were found to have exon8 mutation in cancer group. It is suggested that exon8 mutation occurs at the late stage of gastric cancer, but exon 5, 6, 7 mutation occur in the course ofprecancerous lesion to cancer. Loss of heterozygosity (LOH) of exon4, intron6,APC was 47,37 % (9/19), 8. 73% (2/23), 16. 67 % (3/18) respectively. LOH of exon4 had something to do with poor differentiation, lymph node metastasis,depth of invasion- LOH of exon4 may be one of prognostic marker of gastric cancer. We are led to conclude that p53 gene mutation is an early event and perhaps work together with ras oncogene in gastric carcinogenesis

Genetic aberration in primary hepatocellular carcinoma:correlation between p53 gene mutation and loss-of-heterozygosity on chromosome 16q21-q23 and 9p21-p23

To elucidate the molecular pathology underlying the development of hepatocellular carcinoma (HCC), we used 41 highly polymorphic microsatellite markers to examine 55 HCC and corresponding non-tumor liver tissues on chromosome 9, 16 and 17. Loss-of-heterozygosity (LOH) is observed with high frequency on chromosomal region 17p13 (36/55, 65%), 9p21-p23 (28/55, 51%), 16q21-q23 (27/55, 49%) in tumors. Meanwhile, microsatellite instability is rarely found in these microsatellite loci. Direct sequencing was performed to detect the tentative mutation of tumor suppressor genes in these regions: p53, MTS1/p16, and CDH1/E-cadherin. Within exon 5-9 of p53 gene, 14 out of 55 HCC specimens (24%) have somatic mutations, and nucleotide deletion of this gene is reported in HCC for the first time. Mutation in MTS1/pl6 is found only in one tumor case. We do not find mutations in CDH1/E-cadherin. Furthermore, a statistically significant correlation is present between p53 gene mutation and loss of chromosome region 16q21q23 and 9p21-p23, which indicates that synergism between p53 inactivation and deletion of 16q21-q23 and 9p21-p23 may play a role in the pathogenesis of HCC. Genetic aberration in hepatocellular

ADENOVIRUS-MEDIATED P53 GENE TRANSFER INCREASES THE THERMOSENSITIVITY OF HUMAN GASTRIC CARCINOMA CELL LINES(IN VITRO AND IN VIVO)

Objective: To evaluate the effect of adenovirus-mediated p53 gene (Adp53) on apoptosis andradiosensitivity of human gastric carcinoma cell lines.Methods: Recombinant adenovirus expressing wild-type p53 gene was transferred into four human gastric carcinoma cell lines with different p53 genetic status. p53 proteinexpression was detected by immunohistochemistry assayand western blot assay. Cell survival was assessed using a clonogenic assay. TUNEL assay was used in determination of apoptosis. Four human gastric carcinoma cells infectedwith Adp53 were irradiated with 4Gy and cell cycle distribution and Sub-G1 peak were assayed by flowcytometry. Results: G2/M arrest, apoptosis and inhibition of tumor cell proliferation were induced by infection atAdp53 at 100 MOI which caused high transfer rate ofwild-type p53 and strong expression of p53 protein in four human gastric carcinoma cells. The radio-enhancement ratio of Adp53 at 4Gy were 3.0 for W cell, 3.6 for M cell, 2.2 for neo cell and 2.5 for 823 cell in vitro. Conclusion: Thisstudy demonstrated that Adp53 transfer increased cellularapoptosis and radiosensitivity of human gastric carcinoma cell lines in vitro independently on cellular intrinsic p53status thus supporting the combination of p53 gene therapy with radiotherapy in clinical trials.

Comparative Study of the Effect of Shugan Shuru Granule (疏肝舒乳颗粒) on Pathology and p53 Gene Expression in Patients with Hyperplastic Disease of Breast

Objective: To study the effect of Shugan Shuru Granule (疏肝舒乳颗粒,SSG) on the p53 gene expression in patients with hyperplastic disease of breast (HDB) to indirectly explore the mechanism of SSG’s effect on HDB on the molecular pathological level. Methods: Sixty-six patients with HDB were allocated in the treated group and the control group,with the former treated with SSG and the latter not. All patients underwent breast operation and their diseased mammary tissues were cut out, sectioned, and observed under microscopy with HE staining and immunohistochemical staining, with ABC method adopted to estimate the degree of hyperplasia and p53 gene expression. The severity of HDB was classified into normal, mild, moderate and severe grades (marked as 0 to Ⅲ), according to the degree of hyperplasia in the mammary gland. Results: Hyperplasia in the control group mostly belonged to grade Ⅰ-Ⅲ before treatment, showing overgrowth of gland and proliferation of glandular epithelial cells, which were high columnar shaped, more stratified, with papillary or substantive dysplasia. While in the treated group, most belonged to grade 0-Ⅰ after SSG treatment, with proliferated gland and dysplasia recovered to normal or disappeared. The positive rate of p53 gene expression in the treated group was 9.09%, and in the control group 39.39%, comparison between the two groups showing significant difference (P<0.01), the intensity in the former was significantly weaker than that in the latter.Conclusion: SSG could not only inhibit the proliferation of mammary duct epithelia and lobuli, but also inhibit the over-expression of P53. Therefore, it could be regarded as an effective remedy for treatment of HDB and prevention of mammary cancer genesis.

Protective effects of proanthocyanidins on beta-amyloid peptide (25-35)-induced PC12 cell apoptosis by blocking S-phase and increasing p53 gene expression

BACKGROUND： Current studies related to the effects of proanthocyanidins on Alzheimer＇s disease have focused primarily on the signal transduction pathway of cellular apoptosis. However, the influence of p53 gene expression on cell cycle regulation, with regard to the protective mechanisms of proanthocyanidins, has not been reported. OBJECTIVE： To observe the effect of proanthocyanidins on cell cycle distribution, cellular apoptosis and p53 gene expression in β-amyloid peptide （25-35） （Aβ25-35）-induced PC12 cells cultured in serum-free media, and to investigate the molecular neuroprotective mechanisms of proanthocyanidins with regard to cell cycle regulation. DESIGN, TIME AND SETTING： A parallel, controlled, at the Institute of Biochemistry and Molecular Biology cellular, and molecular study was performed Guangdong Medical College from July 2006 to July 2008. MATERIALS： Proanthocyanidins were provided by Nanjing Xuezi Medical and Chemical Research Center, China; Aβ25-35 was provided by Sigma, USA; PC12 cells were provided by the Institute of Basic Medical Science, Academy of Military Medical Sciences; and rabbit anti-p53 polyclonal antibody was provided by Santa Cruz Biotechnology, USA. METHODS： PC12 cells were cultured in serum-free media for 24 hours. Cells from the model group were treated with 25 μmol/L Aβ25-35 for 24 hours. Cells in the drug protection group were pre-treated with 30 mg/L proanthocyanidins for 1 hour and then treated with 25 μmol/LAβ2^-35 for 24 hours. The control group was not treated. MAIN OUTCOME MEASURES： Flow cytometry was used to detect cell cycle distribution and rate of apoptosis; reverse-transcriptase polymerase chain reaction was used to detect p53 mRNA expression; and Western blot was used to detect p53 protein expression. RESULTS： After treating with 25 μmol/LAβ25-35 for 24 hours, the rate of apoptosis and the percentage of cells in S phase were significantly increased （P 〈 0.01 ）, and p53 mRNA and protein expressions were decreased. Pretreatment with proanthocyanidins for 1 hour blocked the increase in apoptosis and the percentage of cells in S phase in Aβ25-35-induced PC12 cells （P 〈 0.01 ） and increased p53 mRNA and protein expressions. CONCLUSION： Proanthocyanidins blocked apoptosis and S-phase arrest in Aβ25-35-induced PC12 cells cultured in serum-free media. The protective mechanism could be related to increased p53 mRNA and protein expressions.

GROWTH INHIBITION OF HUMAN LARYNGEAL CANCER CELL WITH THE ADENOVIRUS-MEDIATED p53 GENE

Objective: In most laryngeal cancers, the function of p53 gene is down regulated. To explore the potential use of p53 in gene therapy of laryngeal cancer, by introducing wild-type p53 into laryngeal cancer cell line via a recombinant adenoviral vector, Ad5CMV-p53 and analyzing its effects on cell and tumor growth. Methods: A human laryngeal cancer, cell line Hep-2 was used. Recombinant cytomegalovirus-promoted adenoviruses containing human wild-type p53 cDNA was transiently introduced into Hep-2 line. The growth suppression of the Hep-2 cells and established s.c. squamous, carcinoma model was examined. The p53 protein expression was detected using immunohistochemical analysis. Results: The transduction efficiencies of Hep-2 cell line were 100% at a multiplicity of 100 or greater. The p53 protein expression peaked on day 2 after infection and lasted far 5 days. In vitro growth assays revealed cell death following Ad5CMV-p53 infected. In vivo studies, Ad5CMV-p53 inhibited the tumorigenicity of Hep-2 cell, and in nude mice with established s.c. squamous, carcinoma, nodules showed that tumor volumes were significantly reduced in mice that received peritumoral infiltration of Ad5CMV-p53. Conclusion: Adenovirus-mediated antitumor therapy carrying the p53 gene is an efficient method to inhibit laryngeal cancer growth. Transfection of laryngeal cancer cells with the wild-type p53 gene via Ad5CMV-p53 is a potential novel approach to the therapy of laryngeal cancer.

DETECTION OF p53 GENE MUTATION OF BRONCHOSCOPIC SAMPLIES IN THE PATIENTS SUSPECTED TO LUNG CANCER

Objective: To determine the feasibility of detecting p53 gene mutations for early diagnosis of lung cancer using the samples from bronchoscopic examination. Methods: Point mutations of the exon 5-8 of p53 gene were detected in 85 bronchoscopic samples of 35 patients suspected to be lung cancer using silver staining PCR-SSCP. Results: p53 gene mutations were founded in 10 of 35 patients(28.6%). The incidence of p53 gene mutations (14.9%) was obviously higher than the cytological positive incidence(2.9%) in samples of sputum, bronchoalveolar lavage and brush, especially for the sputum(27.7%). In the bronchoscopic biopsy specimens, the incidence of p53 gene mutations (12.5%) was lower than that of pathologic positive result (50.0%). However, in view of all the bronchoscopic samples, there was no statistically difference between cytopathologic positive results (11.8%) and the incidence of p53 gene mutations (14.1%). Although the p53 mutations were most common in the samples from the patients bronchoscopically manifested as neoplasm compared with other manifestations, there was no statistical difference. It is valuable to notice that 3 patients with p53 gene mutation merely presented as bronchial inflammation in bronchoscope. Conclusion: Results indicated that the value of detecting p53 gene mutation for the diagnosis of lung cancer using the bronchoscopic samples was more superior to cytological examination and detection of p53 gene mutations in post-bronchoscopic sputum was easy and effective, may be used as a valuable method for early diagnosis of lung cancer.

Effect of Wild-type p53 Gene Transfection on the Growth and Radiotherapeutic Sensitivity of Human Glioma Cells

Summary： To evaluate the effect of wild type p53 gene on the growth and radiotherapeutic sensitivity of human glioma cells, plasmid PC53 SN3 carrying wild type p53 gene was transfected into U251 cells, p53 gene expression in transfected cells was detected by RT PCR, and the cell growth inhibition and apoptosis in the absence or presence of irradiation were assessed by MTT and flow cytometry. The transfection of p53 gene into U251 cells was confirmed by RT PCR. MTT showed that p53 gene alone induced strong inhibitory effect on the growth of U251 cells （inhibition rate （IR）： （79.60±5.69）%）, The killing effect of irradiation alone on U251 cells was not strong （IR： （17. 06±4.35）%, （17.39±1.67）%, （18.73±4.68）%） and increased with the irradiation doses （3, 6, 9 Gy）. When combined treatment of wild-type p53 gene transfection and irradiation was used, the effect was significantly increased （IR：（80.60±5.35）%, （90.30＋1.67） %, （91.30±2.01） %）. Theapoptosis rate of U251 cells induced by p53 gene transfectionwas 17.38 %. The rate induced by irradiation increased （4. 61%, 4. 84%, 5. 40 %） with the irradiation doses （3, 6, 9 Gy）. Theapoptosis rate was also significantly increased （17.80%, 20.03%, 22.34%） after combined treatment of p53 and irradiation with different doses （3, 6, 9 Gy）. It is concluded that wildtype p53 gene and irradiation could result in synergistic inhibitory effect on the growth of human glioma cells.

DETECTION OF p53 GENE MUTATION IN PLASMA OF PATIENTS WITH GASTRIC CANCER

Objective: To investigated p53 gene mutation in plasma of gastric cancer patients. Methods: DNA extracted from plasma and matched tumor and tumor-adjacent non-cancerous tissues of 96 gastric cancer patients, and DNA from 20 healthy volunteers were studied. Exon 5, 6, 7, and 8 of p53 were amplified by Polymerase Chain Reaction (PCR). The mutation status was analyzed by denaturing high-performance liquid chromatography (DHPLC), followed by direct sequencing of cases with aberrant chromatographic patterns. Results: Heterozygous mutations of p53 gene were detected in 19.9% (19/96) of primary tumor tissues and 5.2% (5/96) of corresponding plasma. All p53 gene mutations detected in plasma DNA consisted with mutations in the matched primary tumor samples. Neither the tumor-adjacent gastric mucosa tissues nor control plasma from healthy volunteers showed p53 gene mutation. No correlation was found between p53 mutation status and clinicopathological features of gastric cancer patients. Conclusion: p53 gene mutation in plasma can be detected in tissues and plasma of gastric cancer patients, which could be applied in screening and surveillance of this disease.

p53 Gene Mutations in Asbestos Associated Cancers

The accumulation of mutant p53 protein in cancer cells was observed by immunohistochemistry analysis. DNA was extracted from paraffin-embedded tissue. Exons 5, 7 and 8 were amplified and studied by PCR-SSCP and sequencing analysis. Ten cases of asbestos associated cancer tissue were studied, of which five cases had adenocarcinoma, and the other five had mesothelioma, squamous carcinoma, small cell lung cancerl adenosquamous carcinoma and malignant lymphoma respectively. Employing monoclonal antibody PAb1801, five cases were found to be mutant p53 protein mpitive. Seven cases were found to have mutations by PCRSSCP. A total of 7 cases (8 mutations) were found to be positive and 4 cases were found to be opitive by both of these analyses. Of the 8 mutations found by SSCP analysis, 4(50%, 4/8)were clustered in exon 8. A high mutation frequency was noticed in adenocarcinoma (80%,4/5). ffequencing analysis on two specimens revealed two hotspot mutations. In codon 234,TAC for tyrooin was mutated to AAC fOr aspar8gine by a T to A transversion of the first letter. In codon 273, CGT for arginine was mutated to AGT for serine by a C to A transversion of the first letter. ln conclusion, the mutation of p53 gene is common in asbestos associated cancers. However, the mutational spectrum of asbestos associated cancers might be different from that of non-asbestos associated cancers.

Successful management of postoperative recurrence of hepatocellular carcinoma with p53 gene therapy combining transcatheter arterial chemoembolization

Transcatheter arterial chemoembolization (TACE) has become the standard treatment for unresectable hepatocellular carcinoma (HCC). But this method has some shortages. p53 gene, which was found to be mutant in many human tumors, has been proved with broadspectrum anti-tumor effects. We reported a 23-year-old patient with recurrent HCC after irregular hepatectomy. The p53 gene was applied to this patient. We injected percutaneously and infused transcatheterally p53 gene (Gendicine, Shenzhen Sibiono Bentech, China) into his recurrent nodules in liver respectively and 4 d later, the patient received TACE therapy. In the 2 mo follow-up, the patient was in good clinical condition with normal liver function and no recurrence was identified. The case report proposed that recurrent HCC could be successfully treated with p53 gene therapy combining TACE.

Infrequent p53 gene mutation and expression of the cardia adenocarcinomas from a high-incidence area of Southwest China

INTRODUCTIONAdenocarcinomas of the cardia are the lesionsarising from the proximal stomach or within 3 cm ofthe gastroesophageal junction.These cancerstended to be advanced at the time of presentation,usually with poor prognosis.In recent decade,the incidence of adenocarcinoma of gastric eardiaand esophagus are increasing steadily,while therehas been a decrease in the proportion of the cancersarising from the distal stomach.The

p53 gene therapy in combination with transcatheter arterial chemoembolization for HCC:One-year follow-up

AIM:To evaluate the efficacy and safety of combination therapy with recombinant adenovirus p53 injection (rAdp53) and transcatheter hepatic arterial chemoembolization (TACE) for advanced hepatocellular carcinoma (HCC).METHODS:A total of 82 patients with advanced HCC treated only with TACE served as control group.Another 68 patients with HCC treated with TACE in combination with recombinant adenovirus-p53 injection served as p53 treatment group.Patients were followed up for 12 mo.Safety and therapeutic effects were evaluated according to the improvement in clinical symptoms,leukocyte count,Karnofsky and RECIST criteria.Survival rate was calculated with Kaplan-Meier method.RESULTS:The total effective rate was 58.3% for p53 treatment group,and 26.5% for control group (P < 0.05).The incidence of gastrointestinal symptoms was lower in p53 treatment group than in control group (P < 0.05).The 3-,6-and 12-mo survival rates were significantly higher for p53 treatment group than for control group (P < 0.01).The combination treatment was well tolerated with such adverse events as fever (51.5%,P=0.006) and pain of muscles and joints (13.2%,P=0.003),which were significantly higher than the chemotherapy.Except for these minor adverse effects,no severe vector-related complications were identified.With respect to the efficacy,patients in p53 treatment group had less gastrointerestinal symptoms (P=0.062),better improvement in tumor-related pain (P=0.003),less downgrade of leukocyte counts (P=0.003) and more upgrade of Karnofsky performance score (P=0.029) than those in control group.The total effective rate (CR + PR) for p53 treatment group and control group was 58.3% and 26.5%,respectively,with distributions of different effect in two groups (P=0.042).The survival rates were 89.71%,76.13%,and 43.30% for p53 treatment group,and 68.15%,36.98%,and 24.02% for control group,respectively,3,6 and 12 mo after treatment,suggesting that the survival rates are significantly higher for p53 treatment group than for control group (P=0.0002).CONCLUSION:The rAd-p53 gene therapy in combination with TACE is a safe and effective treatment modality for advanced HCC.

p53 gene in treatment of hepatic carcinoma:Status quo

Hepatocellular carcinoma (HCC) is one of the 10 most common cancers worldwide. There is no ideal treatment for HCC yet and many researchers are trying to improve the effects of treatment by changing therapeutic strategies. As the majority of human cancers seem to exhibit either abnormal p53 gene or disrupted p53 gene activation pathways, intervention to restore wild-type p53 (wt-p53) activities is an attractive anti-cancer therapy including HCC. Abnormalities of p53 are also considered a predisposition factor for hepatocarcinogenesis. p53 is frequently mutated in HCC. Most HCCs have defects in the p53-mediated apoptotic pathway although they carry wt-p53. High expression of p53 in vivo may exert therapeutic effects on HCC in two aspects: (1) High expression of exogenous p53 protein induces apoptosis of tumor cells by inhibiting proliferation of cells through several biologic pathways and (2) Exogenous p53 renders HCC more sensitive to some chemotherapeutic agents. Several approaches have been designed for the treatment of HCC via the p53 pathway by restoring the tumor suppression function from inactivation, rescuing the mutated p53 gene from instability, or delivering therapeutic exogenous p53. Products with p53 status as the target have been studied extensively in vitro and in vivo . This review elaborates some therapeutic mechanisms and advances in using recombinant human adenovirus p53 and oncolytic virus products for the treatment of HCC.

A p53 genetic polymorphism of gastric cancer: Difference between early gastric cancer and advanced gastric cancer

AIM: To investigate the role of the polymorphism of p53 codon 72 in early gastric cancer (EGC) and advanced gastric cancer (AGC) in Korean patients. METHODS: DNA was extracted from blood samples of gastric cancer patients (n = 291) and controls (n = 216). In the p53 codon 72 genotypes were determined by PCR-RFLP.RESULTS: Patients with gastric cancer had a significantly higher frequency of the homozygous proline (Pro) allele than the control (P = 0.032). Patients with AGC had a significantly higher frequency of the Arg/Arg (arginine) allele (P = 0.038) than EGC and a similar Pro/Pro allele. The signet ring cell type had a higher frequency of the Pro/Pro allele than other types (P = 0.031). The Pro/Pro genotype carries a 3.9-fold increased risk of developing gastric cancer (95% CI, 1.3-15.4, P = 0.039) when compared to Arg/Arg and Arg/Pro genotypes and to develop EGC is a 5.25 fold increased risk (95% CI, 1.8-19.6, P = 0.021). CONCLUSION: The Pro/Pro genotype of the p53 codon 72 polymorphism carries a higher risk for gastric cancer in general and is also associated with a much higher risk for EGC than AGC.

THE RELATIONSHIP OF p53 GENE MUTATION AND TUMORINVASION AND LYMPH NODE METASTASIS IN EARLY GASTRIC CANCER

This study was conducted by determination or mutative p53 gene expression in 32 casesof submucosa early gastric cancer. The relationship of p53 gene mutation and tumorlgenesis andprogress or gastric cancer was evaluated based on the cllnlco-pathological characteristics of early gastric cancer. Results showed that positive rate or P53 Protein expression was 34. 8% in early gastriccancer and p53 mutation related to the hlstology, location or tumor and lymph node metastasis (P <0. 05). Our research suggested that p53 gene ed,resslon closely related to the prognosis of early gastric cancer, and carcinogenesls I,athways may be different according to the positions of stomach.

Correlation of p53 gene mutation and expression of P53 protein in cholangiocarcinoma

瞄准：为了描绘肿瘤，压制或基因 p53 变化和研究 p53 基因变化的关联和在 cholangiocarcinoma 的 P53 蛋白质的表示。方法：36 unselected 的一个总数， cholangiocarcinoma 的冻结的样品被收集。p53 基因地位(5-8 上的前) 和 P53 蛋白质被定序自动化和免疫检验组织化学的染色，与病人的临床的参数结合了。结果：p53 基因变化在 36 中的 22 个被发现(61.1%) 病人。36 中的十九个(52.8%) 病人们为 P53 是积极的蛋白质表示。在在 P53 蛋白质的积极、否定的表示之间的区别和侵略的程度有有效差量。然而，在在变化和非变化之间的病理学的参数没有有效差量。结论：DNA 评估的 p53 基因的改变定序分析是相对精确的。当一个独立人士索引估计 cholangiocarcinoma 的预后， P53 蛋白质的表示不能行动。

Efficacy of Recombinant Adenoviral Human p53 Gene in Treatment of Malignant Pleural or Peritoneal Effusions

Background and objective Once the malignant pleural or peritoneal effusion is developed it is difficult to control.This report presents a new method for controlling the malignant effusions.Methods Forty-eight patients,29 males and 19 females with an average age of 61.2 years old,who were satisfied with the study inclusion criteria,were recruited in this study.Twenty-seven and 21 patients had a malignant pleural and peritoneal effusion,respectively.After draining most of fluids,these patients received intra-cavity infusion of rAd-p53 once per week for 4 weeks,at dose of 2×1012 viral particles(VP) diluted into 200 mL of saline solution for pleural effusions,and 4×1012 VP diluted into 500 mL of saline solution for peritoneal effusions.Results Participants were followed up for a median time of 13.6 month.A total of 11 cases,7 with pleural effusions and 4 with peritoneal effusions achieved a complete response(CR),and 20 cases(12 pleural effusions and 8 peritoneal effusions) had a partial response(PR).The overall response rate is 64.6%.Patients' quality of life,assessed by using Karnofsky performance scale(KPS) scores,was improved by an average of 26.4.The one-year of overall survival rate was 54.2% with a median survival time of 12.5 months.There were no serious side effects observed except for self-limited fever found in 79.8% of the cases.Conclusions Intra-cavity infusion of rAd-p53 is an effective and safe treatment for the patients with malignant pleural or peritoneal effusions,especially for those patients who can't tolerate the standard treatments.

Inhibitory effect of tumor suppressor p33^(ING1b) and its synergy with p53 gene in hepatocellular carcinoma

AIM: To investigate the inhibitory effect of tumor suppressor p33ING1b and its synergy with p53 gene in hepatocellular carcinoma (HCC).METHODS: Recombinant sense and antisense p33ING1b plasmids were transfected into hepatoma cell line HepG2 with lipofectamine. Apoptosis, G0/G1 arrest, cell growth rate and cloning efficiency in soft agar of HepG2 were analyzed after transfection. In three hepatoma cell lineswith different endogenous p53 gene expressions, the synergistic effect of p33ING1b with p53 was analyzed by flow cytometry and luciferase assay was performed to detect the activation of p53 downstream gene p21WAF1/CIP1. In addition, the expression and mutation rates of p33ING1b in HCC tissues were measured by immunohistochemistry and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP).RESULTS: Overexpression of p33ING1b inhibited cell growth of HepG2, induced more apoptosis and protected cells from growth in soft agar. Combined transfer of p33ING1b and p53 gene promoted hepatoma cell apoptosis, G0/G1 arrest and elevated expression of p21WAF1/CIP1. Immunostaining results showed co-localized P33ING1b with P53 protein in HCC tissues and there was a significant relation between protein expression rates of these two genes (P＜0.01).Among 28 HCC samples, p33ING1b presented a low gene mutation rate (7.1%).CONCLUSION: p33ING1b collaborates with p53 in cell growth inhibition, cell cycle arrest and apoptosis in HCC. Loss or inactivation of p33ING1b normal function may be an important mechanism for the development of HCC retaining wildtype p53.

Mutations of p53 gene exons 4-8 in human esophageal cancer

AIM: To characterize the tumor suppressor gene p53 mutations in exon 4, esophageal cancer and adjacent noncancerous tissues.METHODS: We performed p53 (exons 4-8) gene mutation analysis on 24 surgically resected human esophageal cancer specimens by PCR, single-strand conformation polymorphism, and DNA sequencing. RESULTS: p53 gene mutations were detected in 9 of 22 (40.9%) esophageal cancer specimens and 10 of 17 (58.8%) adjacent non-cancerous tissues. Eight of sixteen (50.0%) point mutations detected were G-A transitions and 9 of 18 (50.0%) p53 gene mutations occurred in exon 4 in esophageal cancer specimens. Only 1 of 11 mutations detected was G-A transition and 4 of 11 (36.4%) p53 gene mutations occurred in exon 4 in adjacent non-cancerous tissues.CONCLUSION: Mutation of p53 gene in exon 4 may play an important role in development of esophageal cancer. The observation of p53 gene mutation in adjacent noncancerous tissues suggests that p53 gene mutation may be an early event in esophageal carcinogenesis. Some clinical factors, including age, sex, pre-operation therapy and location of tumors, do not influence p53 gene mutation rates.