Somatic mutation of PTEN in vulvar cancer.

PTEN, a candidate tumor suppressor gene located at chromosome 10q23.3, has been shown to be mutated in approximately 40% of endometrial cancers. Such mutations have also been identified in endometrial hyperplasia, indicating that inactivation of the PTEN tumor suppressor gene is an early event in the genesis of some endometrial cancers. In this study, we have extended the analysis of PTEN in gynecological cancer to include adenocarcinoma of the cervix and vulvar carcinomas. Microdissected tissue (including normal tissues), preneoplastic, and neoplastic lesions were analyzed from 9 patients with cervical cancer and 10 patients with vulvar cancer. Only 1 cervical adenocarcinoma displayed a PTEN mutation. In contrast, five of eight vulvar carcinomas studied harbored PTEN mutations. Alterations were identified in carcinoma in situ as well as squamous cell carcinoma of the vulva. In two patients, PTEN mutations were identified in mucosal regions with mild or focal dysplasia. These results suggest that PTEN is frequently altered in vulvar carcinomas and can be found associated with early dysplastic changes in vulvar mucosa.     

Molecular analysis of PTEN and MXI1 in primary bladder carcinoma

Loss of heterozygosity (LOH) on 10q is associated with late-stage events in urothelial neoplastic progression. The tumor suppressor gene PTEN, which is mutated or homozygously deleted in numerous cancers, maps to a region of 10q within the reported region of minimal loss in bladder tumors. In two recent studies alterations in the PTEN gene occur at a low frequency in bladder tumors displaying 10q LOH. We have screened 35 late-stage bladder tumors for mutations in PTEN and MXI1, both genes mapping to chromosome 10q. Using single-strand conformation polymorphism analysis, we identified 6 tumors harboring mutations in PTEN and 2 additional tumors displaying homozygous deletion at this locus. No MXI1 mutations were identified within the same tumor panel. Of 16 bladder tumor cell lines analyzed, 2 showed homozygous deletion of PTEN and 3 harbored point mutations resulting in an amino acid change. Two cell lines harbored missense mutations in MXI1. We report a significantly higher frequency of PTEN alterations in bladder carcinoma (23%) than was previously recorded, with no accompanying mutations in the MXI1 gene.     

胃癌中PTEN突变在其蛋白异常表达中的作用

背景与目的：胃癌组织中PTEN蛋白表达缺失率较高，本文旨在探讨胃癌组织中PTEN基因突变在其蛋白异常表达中的作用。方法：应用PCR—SSCP—DNA测序和免疫组织化学技术检测53例胃癌组织中PTEN基因突变及其蛋白表达水平的改变。结果：53例胃癌组织中共检测到5例PTEN基因突变，突变率仅为9．4％，低于PTEN蛋白表达缺失率（34．0％）。此5例突变阳性胃癌组织中的PTEN蛋白表达情况为4例阴性、1例弱阳性。结论：基因突变是胃癌组织中PTEN蛋白异常表达的原因之一，突变以外的其他异常改变可能在这一过程中发挥了更为重要的作用。     

Somatic mutation of the APC gene in thyroid carcinoma associated with familial adenomatous polyposis.

We report the existence of both germline and somatic mutations of the APC gene in thyroid carcinomas from familial adenomatous polyposis (FAP) patients. One papillary thyroid carcinoma from a 210-year-old woman, with germline mutation of the APC gene (TCA to TGA at codon 1110), showed a somatic mutation of AAAAC deletion between codons 1060 and 1063. Another somatic mutation of CAG to TAG at codon 886 was also found in one of multiple thyroid carcinomas from a 26-year-old woman with attenuated FAP and germline mutation at codon 175 (C deletion). This is the first evidence that total absence of the normal function of the APC gene is involved in development of thyroid carcinomas in FAP.     

子宫内膜癌及其癌前病变组织中PTEN基因突变的研究

目的:研究抑癌基因PTEN在子宫内膜癌及其癌前病变组织中的突变,并探讨其与子宫内膜癌发生发展的关系。方法:应用聚合酶链反应-单链构象多态性分析(PCR-SSCP)方法检测60例子宫内膜癌、32例子宫内膜癌前病变(复杂型增生12例和不典型增生20例)和20例正常子宫内膜癌组织中PTEN基因的突变情况。结果:子宫内膜癌、子宫内膜癌前病变和正常子宫内膜组织中PTEN基因的突变率分别为36·67%(22/60)、9·38%(3/32)和0(0/20),三者之间差异有统计学意义,P<0·05。统计分析表明PTEN基因突变与子宫内膜癌的组织学分级、组织病理类型和肌层浸润深度有关,P<0·05。子宫内膜癌组织中,PTEN基因突变率在G1~G2级、浅肌层浸润分别高于G3级、深肌层浸润的子宫内膜癌。结论:PTEN基因突变主要发生在组织学分化好、肌层浸润浅的子宫内膜癌中。PTEN基因突变可能是子宫内膜癌发生过程中的早期分子事件。     

子宫内膜癌组织中PTEN基因突变及蛋白表达的检测

背景与目的:肿瘤抑制基因———第10染色体同源丢失性磷酸酶-张力蛋白基因(phosphataseandtensinhomologdeletedonchromosometen,PTEN)被称为子宫内膜的看家基因。但有关PTEN基因在子宫内膜癌发生发展中的确切作用尚不清楚。本研究旨在检测子宫内膜癌组织中PTEN基因的突变及蛋白表达情况。方法:应用聚合酶链反应-单链构象多态性分析(polymerasechainreaction-singlestranconformationpolymorphism,PCR-SSCP)和DNA序列分析法,检测52例子宫内膜癌组织和10例正常子宫内膜组织中PTEN基因第5和第8外显子的突变;免疫组织化学法检测PTEN蛋白的表达,并结合临床病理特征进行分析。结果:子宫内膜癌组织的PTEN基因突变率和蛋白缺失率分别为25%和60%,高于正常子宫内膜组织(0%),差异有显著性(P<0.05)。病理学分级为G1、G2及肌层浸润深度<1/2的组织的PTEN基因突变率高于病理学分级为G3及肌层浸润深度≥1/2者,而病理学分级为G1、G2组织的PTEN蛋白表达缺失率低于病理学分级为G3者,差异有显著性(P<0.05)。PTEN基因突变率和蛋白表达缺失率在子宫内膜样腺癌和其它组织类型之间比较,差异有显著性(P<0.05),而在不同手术分期之间差异无显著性(P>0.05)。结论:PTEN基因突变和蛋白阳性表达常发生在病理学分级较低的子宫内膜癌病例     

PTEN与FHIT在膀胱移行细胞癌中的表达及其临床意义

目的：探讨PTEN与FHIT在膀胱移行细胞癌（bladder transitional cell carcinoma,BTCC）组织中的表达及其临床意义。方法：应用免疫组化技术（SP法）检测62例膀胱移行细胞癌和13例正常膀胱黏膜标本中PTEN与FHIT蛋白的表达情况。结果：PTEN、FHIT蛋白在BTCC表达率分别为56.5%和51.6%,明显低于二者在正常膀胱黏膜中的表达,差异有统计学意义（P〈0.05）;在BTCC中PTEN与FHIT蛋白表达均与肿瘤病理分级和分期密切相关（P〈0.05）,在BTCC标本中PTEN蛋白表达与FHIT蛋白表达呈正相关（r=0.448,P〈0.05）。结论：PTEN、FHIT在BTCC的发生、发展中发挥了重要作用。PTEN、FHIT联合检测可作为预测BTCC生物学行为和预后判断的重要指标。     

Somatic mutation rate of the APC gene.

BACKGROUND: Somatic inactivation of the wild-type APC gene is involved in the development of adenoma of familial adenomatous polyposis. This situation is also true in sporadic adenomas. It is of biological interest to know the somatic mutation rate of the APC gene. METHODS: The number of stem cells of the colon (N) and somatic mutation rate of the APC gene in a stem cell in a year (m) can induce age-specific incidence of adenomas. The number of stem cells was estimated as 10(8) according to previous reports. In the general population, expected adenomas at the end of age n years will be approximately Nm2n2/4. In patients with polyposis, the expected number of adenomas will be Nmn/2. By setting several figures for m, the expected incidence of adenomas was compared with the actual occurrences. RESULTS: If the mutation rate was set between 2/10(6) and 3/10(6) mutations/stem cell/year, the calculated numbers were well fitted to the actual data. Expected adenomas in polyposis patients at the age of 20 and 40 years were 2000 and 4000 and these were within actual experiences. CONCLUSIONS: This is the first study to estimate the somatic mutation rate of the APC gene. The estimated somatic mutation rate of the APC gene was between 2/10(6) and 3/10(6) mutations/stem cell/year.     

野生型PTEN基因高表达对膀胱移行细胞癌EJ细胞的抑癌作用

目的 探讨外源性野生型人酪氨酸磷酸酶（PTEN）基因的高表达对膀胱移行细胞癌EJ细胞的抑癌作用。方法 利用携带人PTEN基因的野生型、磷酸酶域突变型质粒体外分别转染人膀胱移行细胞癌EJ细胞。Western blot检测目的基因PTEN的表达,观察细胞形态变化及超微结构变化;MTIO法检测细胞增殖率及转染细胞对吡柔比星（THP）和丝裂霉素（MMC）的敏感性;Western blot法检测bcl-2蛋白的表达。以空载质粒作为对照。结果 质粒转染后,EJ细胞的PTEN蛋白表达上升75．0％。转染野生型质粒后,EJ细胞异型性低,出现典型凋亡小体,细胞增殖率下降40．1％,bcl-2蛋白表达被下调,并提高了对THP和MMC的敏感性。而转染突变型质粒的EJ细胞则无此作用。结论 野生型PTEN基因在体外对膀胱移行细胞癌EJ细胞增殖有明显抑制作用,诱导细胞凋亡,磷酸酶域突变型PTEN基因无此作用。野生型PTEN的抑癌作用可能与其对bcl-2蛋白表达的下调有关。     

Genetic profile,PTEN mutation and therapeutic role of PTEN in glioblastomas

New therapeutic strategies are needed to improve survival in glioblastoma (GBM) the most malignant astrocytic tumor. We evaluated: a) the genetic status of 22 GBMs by comparative genomic hybridization (CGH); b) the specific role of mutation and/or homozygous deletion of PTEN in the genesis of GBM; and c) the possible therapeutic role of PTEN against GBM, in vitro. CGH demonstrated that the most frequent region of gain was at chromosome 7p, whereas the most frequent losses occurred at chromosomes 10q and 13q. Losses at chromosome 10 were found in 36% of patients, and PTEN was mutated in 27% of the 22 GBMs, including 4 point mutations and 2 homozygous deletions. The possible therapeutic role of PTEN in GBM was also studied in a system based on retroviral infection of the GBM cell line A172, homozygously deleted at the PTEN locus. A172 growth and proliferation rate were reduced by 50% after PTEN transduction. Moreover, we showed that inhibition of cell growth occurred through the PI3K/Akt/p27 pathway. Our findings suggest that PTEN participates in the genesis of GBM, and might be further studied as a candidate therapeutic agent in other testing systems.     

抑癌基因PTEN依赖其磷酸活性诱导人膀胱癌细胞BIU-87失巢凋亡机制

Objective： To investigate the effects and mechanisms of tumor suppressor gene PTEN on the induction of anoikis of human bladder transitional carcinoma cells BIU-87. Methods： BIU-87 cells were transfected with GFP plasmids containing wild-type PTEN or phosphatase inactivating mutant PTEN （C124A-PTEN） in vitro. The PTEN expression and the phosphorylation levels of focal adhesion kinase （FAK） and protein kinase B （PKB/Akt） were detected by Western blotting. Flow cytometry assay and laser scanning confocal microscopy were used to analyze apoptosis in adherent and non-adherent cells. Results： Compared with the control group; PTEN expression in the cells transfected with wild-type PTEN increased to 210%-260%, while the phosphorylation level of FAK and Akt decreased 59% （ P 〈 0.01） and 89% （ P 〈 0.01）, respectively. And the anoikis percentage increased from 8,32 ± 0.57% to 37.62 ± 2.12%, In the cells transfected with C124A-PTEN, neither the phosphorylation of FAK and Akt nor the anoikis percentage had obviously changed, although the PTEN expression enhanced remarkably in comparison with the control. Conclusion： Through its phosphatase activity, tumor suppressor gene PTEN can suppress the phosphorylation of FAK and Akt, and induce anoikis in human bladder transitional carcinoma cells BIU-87.     

Somatic mutation of mitochondrial DNA in cancerous and noncancerous liver tissue in individuals with hepatocellular carcinoma

Unlike other types of cancer, hepatocellular carcinoma (HCC) is usually preceded by chronic inflammation caused by viral infection. The mutation of mitochondrial DNA (mtDNA) in hepatocarcinogenesis associated with viral infection was investigated. Compared with control liver tissue, the frequency of mtDNA mutations was markedly increased in both noncancerous and cancerous liver specimens from individuals with HCC. The accumulation of mtDNA mutations in HCC tissue reflected the degree of malignancy. The frequency of mtDNA mutations in HCC tissue was also greater than that described previously for other types of tumors. These observations suggest that the repeated destruction and regeneration of liver tissue associated with chronic viral hepatitis lead to the accumulation of mtDNA mutations. The genetic instability that results in the high rate of mtDNA mutation in cancerous liver tissue is also consistent with the multicentric hepatocarcinogenesis detected clinically.     

Pathology of bladder carcinoma.

Pathologists play an important role in the evaluation of bladder carcinomas. They are responsible for the diagnosis of the tumor and its categorization, grading, and staging, all of which guides urologists and oncologists in subsequent management. There are considerable differences of opinion as to the categorization and grading of papillary neoplasms, which represent the largest subset of bladder biopsy pathologic specimens.     

MMP-2和PTEN蛋白在膀胱癌组织中的表达及临床意义

目的:探讨基质金属蛋白酶-2(matrix metaloproteinase-2,MMP-2)和PTEN蛋白在膀胱癌组织中的表达及临床意义。方法:应用免疫组织化学PV-6000通用型二步法检测65例膀胱癌及10例正常膀胱组织中MMP-2和PTEN蛋白的表达。结果:MMP-2在正常膀胱组织中不表达,在65例膀胱癌组织中的阳性表达率为56.9%;随着肿瘤细胞病理分级、临床分期的增加,MMP-2阳性表达率逐渐增高,各组间比较差异有统计学意义,P<0.05。PTEN蛋白在正常膀胱组织中均呈阳性表达,在65例膀胱癌组织中的阳性表达率为46.2%;随着癌细胞病理分级、临床分期的增加,PTEN蛋白阳性表达率逐渐减低,各组间比较差异有统计学意义,P<0.05。结论:MMP-2和PTEN蛋白异常表达与膀胱癌的发生发展关系密切,检测两者在膀胱癌组织中的表达,可作为判断膀胱癌发生发展的有用指标。     

Serum alphafetoprotein in bladder carcinoma.

112 cases, of varying ages, which were diagnosed as having carcinoma of the bladder by cystoscopy and biopsy from the tumor, were investigated for the presence of alphafetoprotein (AFP) in the sera. 59 (52.6%) out of the total, showed positive results, and no false positive results occured. Radioimmunoassay was capable of increasing the positivity rate still further. All of the cases were proved by liver scan and laparotomy to be free of metastasis, but all had bilharziasis during childhood, in which there is no factor affecting the liver that is responsible for the release of AFP, as the only species of bilharziasis present in Iraq is that of hematobium.     

Somatic mutations of epidermal growth factor receptor in colorectal carcinoma.

PURPOSE: Somatic mutations of the epidermal growth factor receptor (EGFR) gene may predict the sensitivity of non-small cell lung carcinoma to gefitinib. However, no mutations have been reported for colorectal carcinoma. We therefore analyzed EGFR mutations in colorectal adenocarcinomas by the combined use of laser microdissection and sequencing of genomic DNA. EXPERIMENTAL DESIGN: We examined 11 representative colorectal adenocarcinoma cell lines and 33 clinical samples of colorectal carcinoma. In the clinical cases, we carefully dissected only carcinoma cells from frozen sections by laser microdissection. After DNA extraction and PCR, we examined EGFR mutations by sequencing genomic DNA. RESULTS: None of 11 colorectal carcinoma cell lines exhibited somatic mutations, but 4 of 33 clinical tumors (12%) exhibited mutations in the EGFR kinase domain. This may be the first report of somatic mutations in colorectal adenocarcinoma. CONCLUSIONS: Our findings suggest that a distinct minority of colorectal adenocarcinomas exhibit somatic mutations of EGFR, and these tumors may be susceptible to gefitinib treatment.     

PTEN与肿瘤研究进展

PTEN基因是近年发现的继p53基因之后与肿瘤发生发展关系密切的抑癌基因,在血液系统肿瘤、脑胶质瘤、消化道肿瘤、妇科肿瘤、泌尿道肿瘤、肺癌、骨肉瘤等诸多肿瘤中均检测到该基因的突变或LOH,并发现其蛋白表达水平下调或缺失.