Alteration of p53 and p21 during hepatocarcinogenesis in tree shrews

AIM: To investigate p53 mutation and p21 expression in hepatocarcinogenesis induced by hepatitis B virus (HBV) and aflatoxin B1 (AFB1) in tree shrews, and to reveal the role of these genes in hepatocarcinogenesis.METHODS: Tree shrews were divided into four groups:group A, those infected with HBV and fed with AFB1 (n = 39);group B, those infected with HBV alone (n = 28); group C,those fed with AFB1 alone (n = 29); and group D, normal controls (n = 20). The tree shrews underwent liver biopsies once every 15 wk. Expression of p53 and p21 proteins and genes in the biopsies and tumor tissues of the experimental tree shrews was detected, respectively, by immunohistochemistry,and by Southem blotting and reverse transcription-polymerase chain reaction and sequencing.RESULTS: The incidence of hepatocellular carcinomas (HCC) was higher in group A (66.7%) than that in group B (3.57%) and C (30%). The time of HCC occurrence was also earlier in group A than that in group C (120.0±16.6 wk vs 153.3±5.8 wk, respectively, P<0.01). p53 protein was not detected by immunohistochemistry in all groups before the 75^th wk of the experiment. At the 105^th wk, the positive rates fo p53 were 78.6%, 60% and 71.4% in groups A, B and C, respectively, which were significantly higher than that in group D (10%) (all P<0.05). An abnormal band of p53 gene was observed in groups A and C. The mutation points of p53gene in tree shrews with HCC were at codons 275, 78 and 13. The nucleotide sequence and amino acid sequence of tree shrew's wild-type p53 showed 91.7% and 93.4% homologies with those of human p53,respectively. The immunopositivity for p21 was found before HCC development. The incidence of HCC was significantly higher in tree shrews that were positive for p21 than those negative for p21 (80.0% vs 11.0%, P<0.001).The incidence of HCC in p21 positive animals in group A was significantly higher than those positive for p21 in group C (P<O.05).CONCLUSION: A remarkable synergistic effect on HCC development exists between HBV and AFB1. p53 mutation promotes the development of HCC. HBV and AFB1 may synergistically induce p53 gene mutation, and stimulate ras gene expression, ras gene is activated at the earlier stage during hepatocarcinogenesis, p21 protein may be an early marker, and the alterations of p53 may be a late event in the development of HCC.

Expression of p21^(WAF1) and p53 and polymorphism of p21^(WAF1) gene in gastric carcinoma

AIM:To investigate the relationship between expression of p21^(WAF1) and p53 gene,and to evaluate the deletion and polymorphism of p21^(WAF1) gene in gastric carcinoma (GC). METHODS:Expression of p21 and p53 proteins,and deletion and polymorphism of p21 gene in GC were examined by streptavidin-peroxidase conjugated method (SP) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) respectively. RESULTS:The expression of p21 and p53 was found in 100% (20/20) and 0% (0/20) of normal gastric mucosae (NGM),92.5% (37/40) and 15.0% (6/40) of dysplasia (DP) and 39.8% (43/108) and 56.5% (61/108) of GC,respectively. The positive rate of p21 in GC was lower than that in NGM and DP (P<0.05),while the positive rate of p53 in GC was higher than that in NGM end DP (P<0.05).p21 and p53 were significantly expressed in 63.3% (19/30) and 36.7% (11/30),35.0% (14/40) and 77.5% (31/40),26.7% (4/15) and 80.0% (12/15),30.8% (4/13) and 30.8% (4/13),and 20.0% (2/10) and 30.0%,(3/10) of well-differentiated, poorly-differentiated,undifferentiated carcinomas,mucoid carcinomas and signet ring cell carcinomas.The expression of p21 in well-differentiated carcinomas was significantly higher than that in poorly-differentiated,un-differentiated, mucoid carcinomas and signet ring cell carcinomas (P<0.05). Contrarily,The expression of p53 was increased from well- differentiated to poorly-differentiated and un-differentiated carcinomas (P<0.05).The expression of p21 and p53 in paired primary and metastatic GC (35.3% and 70.6%) was different from non-metastatic GC (62.5% and 42.5%) markedly (P<0.05).The expression of p21 in invasive superficial muscle (60.0%) was higher than that in invasive deep muscle or total layer (35.2%) (P<0.05) and was higher in TNM stages Ⅰ (60.0%) and Ⅱ (56.2%) than in stages Ⅲ (27.9%) and Ⅳ (22.2%) (P<0.05),whereas the expression of p53 did not correlate to invasion depth or TNM staging (P>0.05).The exoression patterns of p53+/p21-,and of p53-/p21+ were found in 5.0% and 82.5% of DP.There was a significant correlation between expression of p21 and p53 (P<0.05).But there was no significant correlation between expression of both in GC (P>0.05).There was no deletion in exon 2 of p21 gene in 30 cases of GC and 45 cases of non-GC,but polymorphism of p21 gene at exon 2 was found in 26.7% (8/30) of GC and 8.9% (4/45) of non- GC,a significant difference was found between GC and non-GC (P<0.05).There was no significant relation between p21 expression of polymorphism (37.5%,3/8) and non-polymorphism (45.5%,10/22) in GC (P>0.05). CONCLUSION:The loss of p21 protein and abnormal expression of p53 are related to carcinogenesis,differentiation and metastasis of GC.The expression of p21 is related to invasion and clinical staging in GC intimately.The expression of p21 protein depends on p53 protein largely in NGM and DP,but not in GC.No deletion of p21 gene in exon 2 can be found in GC.The polymorphism of p21 gene might be involved in gastric carcinogenesis.There is no significant association between polymorphism of p21 gene and expression of p21 protein.

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.

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

Apoptosis,proliferation and p53 gene expression of H.pylori associated gastric epithelial lesions

AIM: To study the relationship between Helicobacter pylori (H. pylori) and gastric carcinoma and its possible pathogenesis by H. pylori. METHODS: DNEL technique and immunohistochemical technique were used to study the state of apoptosis, proliferation and p53 gene expression. A total of 100 gastric mucosal biopsy specimens, including 20 normal mucosa, 30 H. pylori-negative and 30 H. pylori-positive gastric precancerous lesions along with 20 gastric carcinomas were studied. RESULTS: There were several apoptotic cells in the superficial epithelium and a few proliferative cells within the neck of gastric glands, and no p53 protein expression in normal mucosa. In gastric carcinoma, there were few apoptotic cells, while there were a large number of proliferative cells, and expression of p53 protein significantly was increased. In the phase of metaplasia, the apoptotic index (AI, 4.36%+/-1.95%), proliferative index (PI, 19.11%+/-6.79%) and positivity of p53 expression (46.7%) in H. pylori-positive group were higher than those in normal mucosa (P【0.01). AI in H. pylori-positive group was higher than that in H. pylori-negative group (3.81%+/-1.76%), PI in H. pylori-positive group was higher than that in H. pylori-negative group (12.25%+/-5.63%, P【0.01). In the phase of dysplasia, AI (2.31%+/-1.10%) in H. pylori-positive group was lower (3.05%+/-1.29%) than that in H. pylori-negative group, but PI (33.89%+/-11.65%) was significantly higher (22.09+/-8018%, P【0.01). In phases of metaplasia, dysplasia and gastric cancer in the H. pylori-positive group, AIs had an evidently graduall decreasing trend (P【0.01), while PIs had an evidently gradual increasing trend (P【0.05 or P【0.01), and there was also a trend of gradual increase in the expression of p53 gene. CONCLUSION: In the course of the formation of gastric carcinoma, proliferation of gastric mucosa can be greatly increased by H. pylori, and H. pylori can induce apoptosis in the phase of metaplasia, but in the phase of dysplasia H. pylori can inhibit cellular apoptosis. And H. pylori infection can strengthen the expression of mutated p53 gene.

Effects of endotoxin on expression of ras, p53 and bcl-2 oncoprotein in hepatocarcinogenesis induced by thioacetamide in rats

AIM To evaluate the relationship between expression of ras, p53, bcl 2 gene products, and hepatocarcinogenesis since endotoxemia produced from lipopolysaccharide admi nistration and/or the hypophagocytic state of splenectomy significantly accelerated hepatocarcinogenesis induced by thioacetamide. 〖WTH4〗METHODS〓〖WTXFZ〗The hepatocarcinoma model was induced by oral intake of 0 03% thioacetamide for six months. During the induction of hepatocarcinoma model, rats were additionally treated with splenectomy and/or lipopolysaccharide administration. The techniques of flow cytometry, immunohistochemistry and immunoelectronmicroscopy were applied to quantitative analysis of the expression of oncogene proteins. RESULTS In this model system, overexpression of ras p21 protein mainly occurred on precancerous cell population or in early stage of hepatocyte transformation. And the levels of ras p21 declined when nuclear DNA aneuploid increased. Expression of bcl 2 protein slowly and steadily rose with more hepatocytes staying in S+G2M phases as the hepatocarcinoma became more malignant. P53 was moderately expressed during the hepatocarcinogenesis. There was no statistical correlation between endotoxemia levels and the changes of ras, p53 and bcl 2 gene products. CONCLUSION Over expression of oncogene ras p21 was likely to be a precursor of the premalignant hepatocytes and it might be responsible for the initiation of hepatocarcinogenesis. Bcl 2 protein expression is proportional to the severity of the malignancies. P53 may be a key pathway on the transformation and development of hepatocarcinoma. This study confirmed the hypothesis that there are multiple genes and multiple steps involved in hepatocarcinogenesis. Expressions of oncogene proteins reflected the properties of the premalignant and malignant cells, but not directly related to endotoxemia statistically.[JP]

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

Detecting the polymorphism sites of p53 and Fas genes of Han population in Zhejiang province

BACKGROUND： It is of significance for single nucleotide polymorphisms （SNPs）, a difference of rank, which exists widely in biology, genetics and other fields. OBJECTIVE： To detect polymorphism sites in exon-4 of p53 gene, promotor of Fas gene and intron-7 of Fas gene of healthy people in Han nationality in Zhejiang province. DESIGN： Simple random sampling. SETTING： Department of Surgery of the 118 Hospital of Chinese PLA.PARTICIPANTS： A total of 80 healthy people in Han nationality were selected from hospitals in Zhejiang province from August 2005 to January 2006. There were 43 males and 37 females aged from 3 to 78 years with the mean age of 39.5 years, and all subjects were consent. DNA which was used in genetic analysis was selected from peripheral venous blood of all subjects and maintained at -20℃.METHODS： Polymorphism sites in exon-4 of p53 gene, promotor of Fas gene and intron-7 of Fas gene were detected with directly DNA sequencing technique. MAIN OUTCOME MEASURES ： Polymorphism sites in exon-4 of p53 gene, promotor of Fas gene and intron-7 of Fas gene of healthy people in Han nationality in Zhejiang province. RESULTS： A total of 80 samples were involved in the final analysis. SNPs sites were found at the 119^th base of exon-4 of p53 gene （the 72^nd codon of p53 gene）, the 670^th base of upper start codon in promotor of Fas gene （Fas-670）, and the 995^th base of intron-7 of Fas gene, especially SNPs in the 995^th base of intron-7 pf Fas gene, i.e. C→A transversion, was a new site.CONCLUSION ： One unknown SNPs site is discovered in intron-7 of Fas gene of people in Han nationality in Zhejiang province. This study also proves that the 72^nd codon exists in p53 gene and the -670 polymorphism site exists in promotor of Fas gene.

Overexpression and mutations of tumor suppressor gene p53 in hepatocellular carcinoma

AIMS To examine the prevalance of p53 mutations in hepatocellular carcinoma (HCC) from Chongqing area and the relationship between the p53 mutations and clinicopathological features of HCC,as well as the risk factors. METHODS The overexpression and point mutations of tumor suppressor gene p53 in 38 cases of HCC were detected by a sensitive antigen retrieval fluid (ARF) immunohistochemical method and polymerase chain re- action(PCR)-restriction fragment length polymorphism (RFLP),and single strand conformation polymorphism (SSCP)-silver staining analysis. RESULTS The results showed that 16 of 38 HCCs had positive p53 protein (42.1%),7 HCCs had p53 mutation at 249 (18.4 % ) and 2 HCCS had point muta- tion within exon 7 other than 249. Among 9 cases of HCC with mutations,8 cases demonstrated positive p53 protein,its coincidental rate was 88.9%. The overexpression and mutations of p53 were significantly related to the differentiation and metastasis of HCCs. The frequency of p53 mutations was consistent with high prevalence of HBV and a moderate aflatoxin B1 (AFB1) exposure in our area. CONCLUSIONS The results suggest that AFB1 acts synergistically with HBV in the generation of p53 mutations. Furthermore,dietary exposure to AFB1 may mainly contribute to the tumor specific mutation at codon 249,while HBV may account for other scattered mutations in HCC.

P21^(WAF1/Cip1)Gene Expression in Primary Human Hepatocellular Carcinoma and its Relationship with P53 Gene Mutation

Summary: P21 WAF1/Cip1 , an inhibitor of cyclin dependent kinases, is a critical downstream effector in the P53 specfic pathway of growth control. Increased expression of P21 WAF1/Cip1 has been found to reflect the status of the P53 tumor suppressor pathway. We investigated the expression of P21 WAF1/Cip1 in a relatively small, but well characterized group consisting of 28 hepatocellular carcinomas. The samples were previously studied for P53 gene mutation. P21 WAF1/Cip1 expression were identified by in situ hybridization and immunohistochemistry. Positive ISH for P21 WAF1/Cip1 transcripts was found in 18 of 28 cases (64.3 %). All positive cases by ISH showed detectable P21 WAF1/Cip1 protein reactivity by IHC. No relationship was found between P21 WAF1/Cip1 staining and P53 mutational status. No associations were seen with tumor metastasis, size and tumor grade, except for tumor differentiation status which showed higher frequency of P21 WAF1/Cip1 expression in moderate well differentiated HCCs than poorly differentiated tumors ( P <0.05). It is concluded that expression of P21 WAF1/Cip1 is common in HCCs, but does not correlate with P53 mutational status or pathological parameters investigated except for tumor differentiation. Also, there may be other factors beside P53 that regulate P21 WAF1/Cip1 gene expression in HCCs.

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

Immunohistochemical analysis of p53,cyclinD1,RB1,c-fos and N-ras gene expression in hepatocellular carcinoma in Iran

AIM： TO study the effect of some genes especially those involved in cell cycle regulation on hepatocellular carcinoma. METHODS： Paraffin-embedded tissue samples of 25 patients （18 males and 7 females） with hepatocellular carcinoma were collected from 22 pathology centers in Tehran during 2000-2001, and stained using immunohistochemistry method （avidin-biotin-peroxidase） for detection of p53, cyclinD1, RB1, c-los and N-ras proteins. RESULTS： Six （24%）, 5 （20%）, 12 （48%） and 2 samples （8%） were positive for p53, cyclinDl, C-los and N-ras expression, respectively. Twenty-two （88%） samples had alterations in the （31 cell-cycle checkpoint protein expression （RBI or cyclinD1）. P53 positive samples showed a higher （9 times） risk of being positive for RBI protein than p53 negative samples. Loss of expression of RBI in association with p53 over-expression was observed in 4 （66.7%） of 6 samples. Loss of expression of RBI was seen in all cyclinD1 positive, 20 （90.9%） N-ras negative, and ii （50%） C-fos positive samples, respectively. CyclinD1 positive samples showed a higher （2.85 and 4.75 times） risk of being positive for c-los and N-ras expression than cyclinD1 negative samples. CONCLUSION： The expression of p53, RB1 and c-los genes appears to have a key role in the pathogenesis of hepatocellular carcinoma in Iran. Simultaneous overexpression of these genes is significantly associated with their loss of expression during development of hepatocellular carcinoma.

Analysis of N-ras gene mutation and p53 gene expression in human hepatocellular carcinomas

IM To study the relationship between Nras gene mutation and p53 gene expression in the carcinogenesis and the development of human hepatocellular carcinomas (HCC).METHODS The Nras gene mutation and the p53 gene expression were analyzed in 29 cases of HCC by polymerase chain reactionsingle strand conformation polymorphism (PCRSSCP) and immunohistochemistry.RESULTS Thirteen cases of HCCs were p53 positive (448%), which showed a rather high percentage of p53 gene mutation in Guangxi. The aberrations at Nras codon 2-37 were found in 7931% of HCCs and 8077% of adjacent nontumorous liver tissues. More than 2 point mutations of Nras gene were observed in 22 cases (7586%). Twelve cases (4137%) of HCCs showed both Nras gene mutation and p53 gene expression.CONCLUSIONS Nras gene and p53 gene may be involved in the carcinogenesis and the development of HCC. That 38% of HCCs with Nras gene mutation did not express p53 protein indicates that some other genes or factors may participate in the carcinogenesis and the development of HCC.

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.

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.

Extended triplet set C_(343) of DNA sequences and its application to the p53 gene

Recently, much research has indicated that more and more cancers pose a threat to human life. Cancers are caused by oncogenes. Many human oncogenes have been found and most of them are located on chromosomes. The discovery of the oncogene plays a significant role in the treatment of cancer. The p53 tumor suppressor gene has received much attention because it frequently mutates or deletes in tumor cells of most people. Thus, the study of oncogenes is significant. In order to establish the Galois field （GF（7））, the indefinite gene is introduced as D and oncogene is introduced as O, and P. Taking the polynomial coefficients a0, a1, a2 ∈ GF（7） and the bijective function f： GF（7） → {D, A, C, O, G, T, P}, where f（0） = D, f（1） = A, f（2） = C, f（3） = O, f（4） = G, f（5） = T, and f（6）= P, the bijective → may be written as φ（a0 ＋a1x ＋ a2x2）. Based on the algebraic structure, we can not only analyse the DNA sequence of oncogenes, but also predict possible new cancers.

The point mutation of p53 gene exon7 in hepatocellular carcinoma from Anhui Province,a non HCC prevalent area in China

AIM: In hepatocellular carcinoma (HCC) prevalent areas of China, the point mutation of p53 exon7 is highly correlated with Hepatitis B virus(HBV) infection and aflatoxin B intake. While in non-HCC-prevalent areas of China, these factors are not so important in the etiology of HCC. Therefore, the point mutation of p53 exon7 may also be different than that in HCC-prevalent areas of China. The aim of this study is to investigate the status and carcinogenic role of the point mutation of p53 gene exon7 in hepatocellular carcinoma from Anhui Province, a non-HCC-prevalent area in China. METHODS: PCR PCR-SSCP and PCR-RFLP were applied to analyze the homozygous deletion and point mutation of p53 exon7 in HCC samples from Anhui, which were confirmed by DNA sequencing and Genbank comparison. RESULTS: In the 38 samples of hepatocellular carcinoma, no homozygous deletion of p53 exon7 was detected and point mutations of p53 exon7 were found in 4 cases, which were found to be heterozygous mutation of codon 249 with a mutation rate of 10.53%(4/38). The third base mutation(G-T) of p53 codon 249 was found by DNA sequencing and Genbank comparison. CONCLUSION: The incidence of point mutation of p53 codon 249 is lower in hepatocellular carcinoma and the heterozygous mutation of p53 exon7 found in these patients only indicate that they have genetic susceptibility to HCC. p53 codon 249 is a hotspot of p53 exon7 point mutation, suggesting that the point mutation of p53 exon 7 may not play a major role in the carcinogenesis of HCC in Anhui Province, a non-HCC-prevalent area in China.

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.

Overexpression of p53 Gene in Esophageal and Cervical Cancer and the Relationship with Radiotherapy Effects

Objective :To investigate the relationship between p53 -protein overexpression in esophageal and cervical squamous cell cancer and their clinical radiosensitivity. Methods: The immuno-histochemical assays were done for 52 cases with esophageal and cervical squamous cell cancer. The relationship between the assay results and short-term radiotherapy was investigated. Results: p53 overexpression was 52. 38% and 35. 48% respectively, in esophageal cancer and cervical cancer; p53 over-expression in high differentiated squamous cell cancer was lower than those in moderate and poor differentiated cases(P<0. 05). There was no relationship between p53 overexpression and stages(P> 0. 05). In the cases of cervical cancer, p53 overexpression had the less short-term effect(P< 0. 05), and In esophageal cancers, there was no relationship with radiotherapy effect(P>0. 05). Conclusion:This study suggests that y53 gene lias the certain relationship with tumor radiosensitivity.

Exogenous acid fibroblast growth factor inhibits ischemia-reperfusion-induced damage in intestinal epithelium via regulating P53 and P21WAF-1 expression

AIM： To detect the effect of acid fibroblast growth factor （aFGF） on P53 and P21WAF-1 expression in rat intestine after ischemia-reperfusion （I-R） injury in order to explore the protective mechanisms of aFGF. METHODS： Hale rats were randomly divided into four groups, namely intestinal ischemia-reperfusion group （R）, aFGF treatment group （A）, intestinal ischemia group （I）, and sham-operated control group （C）. In group I, the animals were killed after 45 min of superior mesenteric artery （SHA） occlusion. In groups R and A, the rats sustained for 45 min of SHA occlusion and were treated with normal saline （0.15 mL） and aFGF （20 μg/kg, 0.15 mL）, then sustained at various times for up to 48 h after reperfusion. In group C, SHA was separated, but without occlusion. Apoptosis in intestinal villi was determined with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling technique （TUNEL）. Intestinal tissue samples were taken not only for RT- PCR to detect P53 and P21WAF-1 gene expression, but also for immunohistochemical analysis to detect P53 and P21WAF-1 protein expression and distribution. RESULTS： In histopathological study, ameliorated intestinal structures were observed at 2, 6, and 12 h after reperfusion in A group compared to R group. The apoptotic rates were （41.17±3.49）%, （42.83±5.23）%, and （53.33±6.92）% at 2, 6, and 12 h after reperfusion, respectively in A group, which were apparently lower than those in R group at their matched time points （50.67±6.95）%, （54.17±7.86）%, and （64.33±6.47）%, respectively, （P〈0.05））. The protein contents of P53 and P21WAF-1 were both significantly decreased in A group compared to R group （P〈0.05） at 2-12 h after reperfusion, while the mRNA levels of P53 and P21VVAF-1 in A group were obviously lower than those in R group at 6-12 h after reperfusion （P〈0.05）. CONCLUSION： P53 and P21WAF-1 protein accumulations are associated with intestinal barrier injury induced by I-R insult, while intravenous aFGF can alleviate apoptosis of rat intestinal cells by inhibiting P53 and P21WAF-1 protein expression.