RASSF1A、CK19和p53在甲状腺良恶性病变中的表达及临床意义

目的探讨Ras相关区域家族1A（RASSF1A）,细胞角蛋白19和p53基因产物在甲状腺乳头状癌及良性病变中的表达及临床意义。方法采用半定量逆转录聚合酶链反应（RT-PCR）检测,41例甲状腺乳头状癌、19例结节性甲状腺肿、35例甲状腺腺瘤和5例桥本氏病患者标本中RASSF1A、细胞角蛋白19和p53基因的表达情况。结果 RASSF1A、CK19和p53阳性表达率甲状腺乳头状癌与滤泡源性良性病变比较差异有显著性（P〈0.05）;而各良性病变中其表达率差异无显著性（P〉0.05）。半定量结果显示,在甲状腺乳头状癌及良性病变中,上述3种基因产物的mRNA丰度差异性显著（P〈0.01）。在甲状腺滤泡源性良恶性病变中RASSF1A与CK19表达呈负相关（γ=-0.3181,P=0.0013）;RASSF1A与p53表达呈正相关（γ=0.2364,P=0.0179）。结论 RASSF1A、CK19和p53表达产物可作为鉴别甲状腺乳头状癌与良性乳头状增生的重要参考标记物,联合测定效果更好。     

Demonstration of ras and p53 Gene Mutations in Carcinomas in the Forestomach and Intestine and Soft Tissue Sarcomas Induced by N-Methyl-N-nitrosourea in the Rat

The presence of ras family and p53 gene mutations in rat forestomach, intestine and liver tumors and soft tissue sarcomas induced by N methyl- N -nitrosourea (MNU) was examined using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing analysis. In the forestomach squamous cell carcinomas (SCC), Ha- ros and p53 mutations were detected in 2 (40%) and 4 (80%) of 5 cases, respectively. The figures for Ki- ras and p53 gene mutations in adenocarcinomas of the large and small intestines were 3 (18.8%) and 5 (31.3%) of 16 cases. Soft tissue sarcomas in different sites were found to have mutations of Ki- ras in 7 (23.3%)and of p53 in 9 (30%) of 30 cases. One forestomach SCC and 2 soft tissue sarcomas had double p53 mutations in different exons. Single cases of forestomach SCC and intestinal adenocarcinoma had mutations in both Ki- ras and p53 genes. No mutations were found in counterpart benign tumors or hepatocellular adenomas. The p53 mutation spectrum revealed preferential clustering within exon 8 for the forestomach SCCs, and exons 5 and 8 for the intestinal adenocarcinomas, whereas the distribution was evenly spread through exons 5 to 8 in soft tissue sarcomas. All the detected ras or p53 mutations were G:C to A:T transitions. These results indicate firstly that specific Ki- ras , Ha- ras and p53 gene mutations in MNU-induced lesions are related to particular alkylation sites (G:C to A:T transitions) and secondly, although not essential, Ki- ras , Ha- ras or p53 gene mutations may be involved in the progression stage of forestomach, intestine and soft tissue neoplasms induced by MNU.     

胃癌中CD44V6与p53蛋白的表达及其意义

 目的　分析胃癌研究中的两个热点基因蛋白CD44V6和p53与胃癌发生、发展及转移的关系。方法　运用免疫组化法，检测78例原发胃癌及癌旁良性病变的CD44V6及p53基因蛋白的表达。结果　30例胃癌出现CD44V6的阳性表达38.5%(30/78)，癌旁良性病变中未检测到其表达；侵及浆膜或具有淋巴结转移及远距离转移者，V6表达率明显高于无浆膜受侵或无淋巴结转移及远距离转移者。肠型胃癌的V6表达率明显高于弥漫型胃癌的，但弥漫型胃癌中V6表达与淋巴结转移呈显著相关性，而肠型胃癌中则否。有28例胃癌检测到p53蛋白的积聚35.9%(28/78)，p53阳性与各种临床病理因素均无关，但癌旁良性病变中却可见p53阳性。结论　CD44V6表达预示胃癌具有较强的侵袭转移能力，而p53基因蛋白的异常表达与细胞的早期癌变有关。     

Immunohistochemical study of oncogene product ras p21, c-myc and growth factor EGF in breast carcinomas.

The expression of the oncogene products ras p21, c-myc and the growth factor EGF (epidermal growth factor) was studied immunohistochemically in the tissue of 119 benign and malignant human breasts. In most cases, histologically normal breast tissues and benign lesions were found to be negative or poorly-expressive for reactivity with each antibody. Similar findings were observed in carcinoma in situ. Invading breast carcinomas demonstrated a significantly higher percentage of stained cells than that observed in benign lesions or carcinoma in situ; forty-two of 66 invasive breast carcinomas (63.6%) were highly-expressive for ras p21, thirty-eight (57.6%) for c-myc and twenty (30.3%) for EGF, but overall correlations between each oncogene expression and the clinical stage, tumor size or degree of differentiation were not found. The overall 5-year survival rate was studied in 58 patients with Stage II and III in association with each oncogene or EGF expression. Their survival rate was significantly effected by the EGF expression (0.05 less than p less than 0.1) but not by ras p21 or c-myc expression. Analysis of 36 specimens available with ER (estrogen-receptor) level revealed a significant correlation between the ER status and c-myc or E2 (estradiol) and a significant inverse correlation between ER status and ras p21 or EGF expression (P less than 0.05). The expression of ras p21, EGF and c-myc was not associated with metastatic tumor progression.     

ras mutations are associated with aggressive tumor phenotypes and poor prognosis in thyroid cancer.

PURPOSE: ras oncogenic activation has long been demonstrated in thyroid carcinomas of follicular cell derivation, but no consistent relationship has been shown between mutations and clinicopathologic features. MATERIALS AND METHODS: We analyzed H-, K-, and N-ras mutations by polymerase chain reaction-single-strand conformational polymorphism followed by DNA sequencing in 125 thyroid carcinoma specimens from 107 patients, to include tumors covering the entire spectrum of thyroid tumor differentiation. RESULTS: Mutations were identified in four (8.2%) of 49 well-differentiated carcinomas (WDCs; two [6.7%] of 30 of the tumors were papillary carcinomas, two [10.5%] of 19 of them were follicular carcinomas), in 16 (55.2%) of 29 poorly differentiated carcinomas (PDCs), and in 15 (51.7%) of 29 undifferentiated carcinomas, with a significant association between ras mutation and poorly or undifferentiated tumors (P <.001). Twenty-six (74.3%) of 35 patients with ras-mutated tumors died as a result of disease as opposed to 23 (31.9%) of 72 patients with tumors lacking the mutations. Among patients with differentiated thyroid carcinomas (WDC and PDC), 11 (55.0%) of 20 patients with mutated tumors died as a result of disease as opposed to nine (15.5%) of 58 patients with wild-type ras tumors, and the correlation was independent of tumor differentiation and stage (P =.016). K-ras codon 13 mutations (all with G-A nucleotide transitions resulting in Gly>Asp substitution) and single activating mutations in any of the ras genes were also independent predictors of poor survival in differentiated thyroid carcinomas (P =.027 and P =.007, respectively). CONCLUSION: These findings demonstrate that ras mutations are a marker for aggressive cancer behavior and indicate a possible role of ras genotyping to identify thyroid carcinoma subsets associated with poor prognosis.     

ras p21及p53基因的表达与胃癌生物学行为关系的探讨

应用SP免疫组化法检测1980～1989年存档的33例胃癌及其癌旁组织石蜡包埋标本的ras p21和p53基因表达情况,并与临床、病理和随访资料进行对比分析。结果显示:胃癌标本的ras p21阳性表达7例(21.21％),p53蛋白的阳性表达11例(33.33％)。ras p21的阳性表达与病理类型、性别、年龄、民族以及肿瘤部位无关,但肿瘤浸润深度及有无淋巴结转移与ras p21阳性表达之间显著相关。生存不足1年组的ras p21表达阳性率(50％)明显高于1～5年组(22.22％)和5年以上组,表明P21蛋白的表达与胃癌的浸润、进展和预后有关,提示ras p21的检测有可能成为胃癌预后指标,并有指导临床治疗的意义。p53蛋白的表达与患者的临床病理状况无显著相关,提示p53基因的改变可能主要发生在癌变早期,对胃癌的发生起关键作用,但并不影响胃癌细胞的生物学行为。p~53蛋白的表达与ras p~21蛋白表达之间无明显关系。     

Ras and p53 expression in non-small-cell lung-cancer patients - p53 over-expression correlates with a poor prognosis

Expression of the tumor suppressor gene p53 and the ras oncogene were examined in 46 tumor and nodal specimens of non-small cell lung cancer (NSCLC) using the antibodies p53 pAb 240 and ras Y13-259 respectively. p53 expression was elevated in 46% and ras p21 was over-expressed in 85% of the tumor specimens analyzed. Fifteen cases of benign lessions were also assessed for both ras p21 and p53 expression; all were found to have negative staining. p53 over-expression was found to correlate with a poor prognosis in both the tumor specimens (p<0.05) and in the nodal tissues (p<0.005). Ras p21 over-expression was found to be associated with survival (p<0.1) in both the tumor and the nodal specimens. Stage of the disease correlated with survival; similarly both p53 and ras p21 over-expression correlated with stage. No correlations were found with the pathological grade of the tumors nor with a history of smoking or duration of smoking. No K-ras mutations at codon 12 were observed in a further 15 NSCLC specimens analyzed. These results indicate that the p53 gene in particular plays a role in the stages of NSCLC.     

Comparative immunohistochemical studies of bcl-2 and p53 proteins in benign and malignant ovarian endometriotic cysts

BACKGROUND: A number of histologic and epidemiologic studies have suggested an association between endometriosis and ovarian carcinoma. Some reports have described a transition from endometriosis to atypical endometriosis to carcinoma. Using immunohistochemistry, the authors compared staining patterns in benign endometriotic cysts with ovarian tumors and the endometriotic cyst lining from which they arose, in an attempt to identify sequential or etiologic correlations. METHODS: One hundred thirteen formalin-fixed, paraffin-embedded sections were studied (30 benign ovarian endometriotic cysts, 24 endometriotic cysts containing endometrioid carcinomas, 19 endometriotic cysts harboring clear cell carcinomas, and 40 ovarian papillary serous cystadenocarcinomas). All sections were immunostained with anti-bcl-2 and anti-p53 antibodies using the streptavidin-biotin method. RESULTS: bcl-2 was reported to stain 23% of benign endometriotic cysts, 67% of endometrioid carcinomas, 73% of clear cell carcinomas, and 50% of papillary serous carcinomas. Approximately 42% of benign endometriotic lesions adjacent to the endometrioid carcinoma and 73% adjacent to clear cell carcinomas were found to stain for bcl-2 (p = 0.274 [not significant (NS)] and P = 0.008, respectively). p53 staining was negative in the benign endometriotic cyst group and was positive in 37-55% of the group with tumors. p53 staining was positive in 25% of the benign endometriotic lesions next to the endometrioid carcinoma and in 9% of the benign endometriotic lesions next to clear cell carcinoma (P = 0.014 and P = 0.239 [NS], respectively). CONCLUSIONS: The results of the current study suggest that alterations in bcl-2 and p53 may be associated with the malignant transformation of endometriotic cysts.     

Expression of p21 (WAF1/CIP1) protein in clinical thyroid tissues.

p21 (WAF1/CIP1) protein expression in various thyroid tissues, including thyroid carcinoma, was studied by means of immunohistochemistry using anti-p21 monoclonal antibody. Normal follicles and hyperplasias rarely expressed p21, whereas immunohistochemically positive cells were also too rarely found in follicular adenomas to justify these cases being classified as positive. Twenty eight of the 93 carcinomas examined (30.1%), however, were positive for p21. Of the p21-positive cases, 80% of the undifferentiated and 28.6% of the poorly differentiated carcinomas showed lesions co-expressing p21 and p53. If diffuse immunoreactivity of p53 reflects the p53 mutation, our results indicate that p21 in these carcinomas can be induced by p53-independent as well as by p53-dependent pathways. On the other hand, well-differentiated carcinomas did not co-express these two proteins and it therefore remains unclear whether p53-independent or p53-dependent pathways are predominant in this type of carcinoma. The incidence of expression of p21 was very similar in undifferentiated (26.3%), poorly (28.0%) and well-differentiated carcinomas (32.7%), even though they are characterised by different degree of malignancy. Furthermore, no correlation between p21 expression and either clinical parameters or patient''s prognosis could be established. These results suggest that p21 is only marginally related to the characteristics of thyroid carcinoma and can play only an adjuvant role in regulating the progression of this carcinoma.     

子宫内膜息肉与子宫内膜癌中Ki-ras 基因表达及临床意义

 目的　探讨 Ki-ras基因激活与子宫内膜癌中的发生发展关系及子宫内膜息肉与子宫内膜癌的关系。方法　对子宫内膜癌及癌前病变组织进行 Ki- ras蛋白免疫组化测定 ,并利用 PCR技术检测 Ki-ras基因第一外显子 1 2密码子突变。结果　 Ki- ras蛋白广泛存在于子宫内膜癌和癌前病变组织中 ,癌前病变 Ki- ras表达为 1 1 .9% ,癌组为 62 .96% ,P<0 .0 5。Ki-ras表达与细胞恶性程度呈正相关。 PCR-RFLP检测与免疫组化结果类似。结论　 1 .Ki-ras基因激活可导致细胞周期增殖失控 ,是内膜癌发生发展的一个重要环节 ;2 .动态观测子宫内膜息肉中的 p21 ras表达阳性者 ,对子宫内膜癌的早期发现可能有积极意义。     

甲状腺癌组织中H-ras基因突变及蛋白表达的预后价值

对５４例甲状腺癌标本分别用ＰＣＲ－ＲＦＬＰ法检测Ｈ－ｒａｓ基因第１２位密码子的突变及免疫组化法检测ｐ２１ｒａｓ蛋白，并用时序检验分析ｒａｓ基因突变和ｐ２１ｒａｓ蛋白表达与甲状腺癌的关系。结果发现，甲状腺癌中１８例（３３．３％）有ｒａｓ基因突变和４９例（９０．７％）有ｐ２１ｒａｓ蛋白过度表达。临床分期晚、分化程度低的甲状腺癌突变率较高，具有Ｈ－ｒａｓ原癌基因突变和ｐ２１ｒａｓ蛋白阳性的病例有较高的复发率和死亡率。表明ｒａｓ基因突变及其蛋白过度表达在甲状腺癌的发生和发展过程中发挥作用，是预后不良的标志     

Prognostic Significance of p53 and ras Gene Abnormalities in Lung Adenocarcinoma Patients with Stage I Disease after Curative Resection

We investigated the prognostic significance of p53 gene abnormalities and ras gene mutations in patients with curatively resected stage I lung adenocarciiioma. Formalin-fixed and paraffin-embedded tissues were obtained from 30 patients who had undergone curative resection for stage I lung adenocarciiioma. Abnormalities of the p53 gene were detected using polymcrasc chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis and immunohistochemistry and ras mutations were detected using PCR-restriction fragment length polymorphism (RFLP) analysis. Both univariate and multivariate analyses were performed to assess the relationship between the presence of abnormalities of these genes and the patients'disease-free survival. Eleven tumors (37%) had mutated p53 sequences and 11 (37%) showed p53 overexpression. A total of 15 tumors (50%) had p53 gene abnormalities and the concordance rate was 73%. Seven tumors (23%) showed mutated ras sequences. The univariate analysis revealed that the disease-free survival of patients with any p53 abnormality was shorter than that of those without abnormalities ( P= 0.02, generalized Wilcoxon test), and survival of those with p53 protein overexpression was more significantly shorter ( P= 0.003, generalized Wilcoxon test). Multivariate analysis using the Cox proportional hazards model indicated that the presence of p53 abnormalities was a significantly ( P =0.01) unfavorable prognostic factor. There was no significant correlation between the presence of ras mutation and survival. These results suggest that analysis of the p53 gene may be helpful for the selection of high-risk patients for clinical trials of adjuvant therapy for stage I lung adenocarcinoma.     

Absence of ras Mutations and Low Incidence of p53 Mutations in Renal Cell Carcinomas Induced by Ferric Nitrilotriacetate

Renal cell carcinomas induced in male Wistar rats by iron chelate of nitrilotriacetate (Fe-NTA) were examined for mutations in ras oncogenes and p53 tumor suppressor gene. Fourteen primary tumors and two metastatic tumors from 11 animals were evaluated. Exons 1 and 2 of the H-, K-, and N- ras genes were amplified by polymerase chain reaction (PCR), and the presence of mutations was examined by direct sequencing. Exon 5 through exon 7 of p53 gene, including the 3'half of the conserved region II and the entire conserved region III through V, were surveyed for point mutations by PCR-single stranded conformation polymorphism (SSCP) analysis. Direct sequencing of the ras genes showed no mutations in codon 12, 13, or 61 among the tumors evaluated. SSCP analysis of p53 gene exon 6 indicated conformational changes in two primary tumors. One tumor had a CCG-to-CTG transition at codon 199, and the other had an ATC-to-ATT transition at codon 229 and two nonsense C-to-T transitions. These results suggest that neither ras genes nor p53 gene play a major role in the development of renal cell carcinomas induced by Fe-NTA.     

Expression of bcl-2, c-erbB-2, p53, and p21 (waf1-cip1) protein in thyroid carcinomas

The study was carried out on 53 patients who had thyroid cancer with various degree of differentiation. We studied the expression of bcl-2, a-erbB-2, p53, and p21 ras protein. The protein encoded by bCL-2 proto-oncogene is implicated in the prolongation of cell survival by blocking programmed cell death, i.e. apoptosis. The role of p53 and bcl-2 genes in the regulation of apoptosis has important implications in oncogenesis. Wild-type p53 is thought to promote apoptosis, whilst mutant p53 has a similar effect on apoptosis as bcl-2 that is inhibition of programmed cell kinase activity. C-erb-2 protein overexpression is currently being evaluated as a potential risk factor in breast cancer patients? The ras gene family codes for a 21 kD protein (p21), which binds guanine nucleotides and possesses GTPase activity. Through this mechanism, the ras p21 protein participates in the control of cell proliferation, possibly as a signal transducer from cell surface receptors to the nucleus. Activation of ras genes has been implicated in neoplastic transformation of cells. The aim of our study is to evaluate the expression of these markers in thyroid carcinomas. All immunohistochemical study was performed in paraffin-embedded tissues pathology specimen. Any well differentiated tumor in our study was positive for bcl-2 protein. C-erb-2 immunostaining was present in tumor samples in 60% of cases. In most cases, specific membrane staining as well as a weak cytoplasmic positivity of tumor cells were seen. Immunoreactivity for p53 was positive only in 10% of cases. By immunostaining, p21 protein was expressed in 55% of the 53 tumors tested, with different degree of expression. Only some poorly differentiated tumours were positive for bcl-2, furthermore all markers tested were strongly positive in these tumours. In conclusion, our results indicate that bcl-2, c-erbB-2, p53, and p21 ras protein are differently expressed in thyroid carcinomas in relation to the degree of aggressiveness and differentiation.     

p53基因在甲状腺癌中的突变研究

目的：为探讨p53基因突变与甲状腺癌的发生、发展及预后的关系。方法：应用PCR单链构象多态性（SSCP）分析技术,对p53基因第7,8外显子突变进行了检测和分析。结果：在37例甲状腺癌中有11例在第7.8外显子发生突变,突变率为29.9％。p53基因突变在复发的患者中显著高于未复发的患者;p53基因突变与转移、组织学类型和分化状况无显著差异。结论：p53基因的突变可能与甲状腺癌患者预后有关。     

Expression and alteration of ras and p53 proteins in patients with lung carcinoma accompanied by idiopathic pulmonary fibrosis

BACKGROUND: The ras oncogene and the p53 tumor suppressor gene play important roles in the carcinogenic process of lung carcinoma. The authors evaluated whether alterations of the ras and p53 proteins may contribute to the development of lung carcinoma in patients with idiopathic pulmonary fibrosis (IPF) and whether such alterations may explain the high incidence of lung carcinoma among patients with IPF. METHODS: Lung tissues were obtained from 35 patients who had IPF without complications of lung carcinoma and from 36 patients who had IPF with complications of lung carcinoma. Altered expression of ras and p53 proteins was evaluated by immunohistochemistry, and mutations of both genes were evaluated by polymerase chain reaction-single strand conformation polymorphism and sequencing analyses. RESULTS: The frequency of expression of ras protein in type II alveolar pneumocytes was significantly greater in lung tissues from patients with IPF who had lung carcinoma compared with lung tissues from patients with IPF who did not have lung carcinoma (75% vs. 40%, respectively; P < 0.01). K-ras point mutation in codon 12 (GGT to GTT transversion) was detected in lung tissue with interstitial pneumonia, in which ras protein was overexpressed in type II alveolar pneumocytes obtained from 2 of 41 patients with IPF complicated by lung carcinoma, causing amino acid substitution (Gly to Val) in both patients. A p53 mutation was detected in three of six lung tissue samples from patients who had IPF lung with positive p53 immunoreactivity, and multiple mutations were detected in two samples. CONCLUSIONS: Expression of ras protein in type II alveolar pneumocytes and mutation in the codon 12 of K-ras gene in lung tissue may contribute to the induction of lung carcinoma in patients with IPF. Furthermore, the presence of multiple mutations in the p53 gene may explain the high incidence lung carcinoma in patients with IPF.     

p73和p63蛋白在胰腺癌组织中过表达的意义

目的:探讨p53家族新成员p73和p63蛋白在胰腺癌组织中过表达的意义。方法:应用免疫组化LSAB法检测75例人胰腺癌组织中p73和p63蛋白的过表达。结果:p73和p63蛋白在人胰腺癌中的过表达率分别为46·7%(35/75)和42·7%(32/75),p73蛋白在胰腺囊腺癌中的过表达率88·9%(8/9)明显高于导管腺癌41·8%(23/55),P=0·009,且p73蛋白过表达与胰腺癌淋巴结转移、肿瘤大小、神经侵犯和p53表达呈显著负相关性,P<0·05;在腺鳞癌或腺癌伴鳞状上皮化生中p63蛋白的过表达率(100%,13/13)明显高于导管腺癌(40·0%,22/55),P=0·007,但p63蛋白过表达与胰腺癌临床病理学指标及p53和增殖细胞核抗原(pro-liferatingcellnuclearantigen,PCNA)表达间无明显相关性。结论:p73蛋白低表达可能在胰腺癌发生中起重要作用;p63蛋白过表达与腺鳞癌或腺癌鳞化有关。     

Overexpressions of Ha-ras and p53 predict the prognosis of patients with non-small-cell lung carcinoma

Activationofprotooncogenesandinactivationoftumor-suppressorgeneshavebeenshowntoplayanimportantroleincarcinogenesis.Inhumantumors,alterationsoftherasprotooncogenesandp53tumor-suppressorgenehavebeenwidelyinvestigated[1-6].Thethreemembersoftherasprotooncogenefamily,Ki-ras,Ha-ras,andN-ras,encodep2l(ras)[ras][1,2].Pointmutationsoftherasprotooncogenes,resultinginmutatedformsofrasp21,andanenhancedexpressionofthenormalcellularrasp2laretwomechanismsknowntoleadtoactivationoftherasprotooncogenefamily[7,…     

Immunohistochemical demonstration of ras p21 oncogene product in normal, benign, and malignant human thyroid tissues

The p21 protein product of the cellular oncogene ras, designated ras p21, has been detected immunohistochemically in normal, benign and malignant human thyroid tissues. With the monoclonal antibody RAP-5 generated against a synthetic peptide corresponding to amino acid positions 10 to 17 of the ras p21 protein and an avidin-biotin-peroxidase complex (ABC), the expression of the ras p21 was evaluated in paraffin-embedded sections. Western blot analysis using fresh thyroid carcinoma tissue revealed double protein bands, one band was at molecular weight 21,000 and the other was a more rapidly migrating band at the molecular weight 17,500. Immunohistochemically, papillary adenocarcinomas of the thyroid showed moderate to intense stainings for ras p21 in most cases. Cytoplasmic and apical surface stainings were the most common patterns of immunoreactivity. Adenomas showed variable ras p21 positivity in cytoplasm and apical surface stainings of adenomas were negative to borderline in most cases. The cytoplasm of tissues of Hashimoto's thyroiditis, Graves' disease, and normal thyroid tissues was uniformly ras p21 positive, but the apical cell surface was nonreactive for ras p21 in all tissues. Judging from the findings obtained on this large series of normal, benign, and malignant thyroid tissues, the elevation of ras p21 may be a common event in thyroid neoplasm, and especially elevated ras expression in the apical cell surface may be characteristic to papillary carcinomas of the thyroid. This suggests that apical surface expression of ras p21 may be important in the development of thyroid carcinomas and be useful in differentiation of papillary adenocarcinoma.     

Homozygous proline at codon 72 of p53 as a potential risk factor favoring the development of undifferentiated thyroid carcinoma

The p53 tumor suppressor gene is altered in human cancer. A common polymorphism occurs at codon 72 of exon 4, with two alleles encoding either arginine (CGC) or proline (CCC). No data exist about the association of a distinct codon 72 variant with the histological subtypes of thyroid carcinoma. We developed a new one-step real-time PCR assay on the LightCycler to detect codon 72 polymorphism in the p53 gene. We studied 21 papillary, 18 follicular and 22 anaplastic thyroid carcinomas and compared them with 15 adenomas and 36 normal thyroid tissues (controls); moreover, we compared the cases for histological, clinical and demographic variables and genotype prevalence. In controls, the frequency of the three genotypes Arg/Arg, Arg/Pro, and Pro/Pro was 41.7, 50.0 and 8.3%, respectively. The homozygous proline was not found in benign thyroid adenomas and differentiated thyroid carcinomas. In contrast, all undifferentiated thyroid carcinomas (100%) had the homozygous proline phenotype. The frequency of the two other genotypes Arg/Arg and Arg/Pro was 66.7% and 33.3% in adenomas, 81.0% and 19.0% in papillary thyroid carcinomas, and 83.3% and 16.7% in follicular thyroid carcinomas, respectively. Comparing the genotypes with tumor stage, no correlation was found. However, lymph node and distant metastases status showed a statistically significant prevalence for the homozygous phenotypes Arg/Arg and Pro/Pro. There was no association between a special genotype and age and sex. We conclude that homozygous proline is a potential risk factor favoring the development of an undifferentiated thyroid carcinoma, and that the homozygous phenotypes at codon 72 of p53 are associated with a poorer prognosis of thyroid carcinoma.