Frequency Of P53 Research Articles

Clonality Analysis for the Relationship between the Pulmonary Combined Neuroendocrine Carcinoma and “the So-Called Reported Histologic Transformation”

Histologic transformation (HT) is common following targeted therapy in adenocarcinoma. However, whether the transformed tumor is a new component or a combined neuroendocrine carcinoma (C-NEC) remains controversial. We aimed to explore the relationship between pulmonary C-NEC and HT. Macro-dissection was performed on different components of surgically resected C-NEC samples. Molecular alterations and clonal evolution were analyzed using whole exome sequencing (WES). The gene statuses for TP53 and RB1 were determined using immunohistochemistry (IHC) and WES to analyze the relationship between C-NEC and reported HT. Sixteen combined small-cell lung cancer patients and five combined large-cell neuroendocrine carcinoma patients were enrolled. The frequency of p53 and Rb inactivation, assessed using IHC in NEC and non-NEC components, was 76.2/76.2% and 66.7/61.9%, respectively. The expression consistency between the components was 81.0 and 85.7% for p53 and Rb, respectively. The frequencies of TP53, RB1, and EGFR mutations, assessed using WES in NEC and non-NEC components, were 81.0/81.0%, 28.6/28.6%, and 42.9/42.9%, respectively. The concordance rates for TP53, RB1, and EGFR were 90.5, 71.4, and 90.5%, respectively. The consistency rate between IHC and WES was 81.0 and 61.9% for TP53 and RB1, respectively. The different components had a common clonal origin for the 21 C-NECs in the clonal analysis, consistent with previous studies on HT. Our study shows that IHC is more sensitive for Rb detection and C-NEC, and the reported HT may be due to differences in evaluations between pathologist and clinicians. Assessing the p53/Rb and EGFR status for such cases would help in recognizing potential transformation cases or uncovering potential combined components.

The Comparative Study of the Frequency of P53 and Ki67 Markers in Ovarian Epithelial Tumors and Their Relationship with Survival in Patients Presenting to Shahid Sadoughi Hospital of Yazd in 2013–2017

Ovarian cancer is the fifth cause of cancer death among women. P53 gene and Ki67 can play a significant role in the progression of tumors. This study was conducted to review the frequency of P53 and Ki67 markers in different types of ovarian epithelial tumors and their relationship with the prognosis of the disease. This descriptive analytical study was done on all paraffin-embedded blocks of patients with ovarian surface epithelial tumors (malignant, benign, and borderline) referred to pathology ward of Shahid Sadoughi educational General Hospital from 2013 to 2017 by using the census method. Ki67 and P53 immunohistochemical tests were then performed on all the samples. Data such as (age, pathology report, survival status, affected side, size of tumor) were extracted from the hospital folders. Data were analyzed in SPSS version 22. P < 0.05 was set as the level of statistical significance. A total of 86 cases, including 40 serous and mucinous carcinomas, 36 serous and mucinous cystadenomas, and ten serous and mucinous borderline tumors, were examined. The mean age of the patients was 44.29 ± 16.91 years, and their age range was 15–79. A significant relationship was found between the type of tumor and the frequency of P53 and Ki67 (P < 0.05). Nonetheless, no significant relationships were observed between tumor grade and these two markers. Ki67 staining susceptibility was significantly higher in the undifferentiated tumors than in the others (P < 0001). The mean survival was 40.67 months, and a significant relationship was observed between age and survival (P < 0.002) and age and the frequency of P53 and Ki67 and tumor type (P < 0.05). The results of this study showed that both P53 and Ki67 are predictors of overall survival, tumor type, disease grade, and disease prognosis in patients with different ovarian epithelial tumors and can be used in them alongside biopsy.

Vitiligo: Skin Malignancies and Tumor Suppressive Marker P53

Background: Vitiligo is common autoimmune pigmentary disorders where there are no cutaneous cancers have been reported among affected patients. Objective: To estimate the frequency P53 marker and its role in protection against skin cancers in patients with vitiligo. Patients and Methods: This study took place in the Department of Dermatology, Baghdad Hospital during the period from May 2009-September 2010. It is composed of two parts: Part I was case descriptive study performed to record any association of skin malignancies in 300 vitiligo patients, 155 females and 145 males, while Part II was case observational, controlled, histochemical, investigative study to estimate the frequency of P53 in vitiliginous skin and adjacent normal skin in comparison with control group. Skin biopsies were taken from 25 patients, one from the centre of vitiliginous patch and the other about 0.5 cm adjacent to the patch (normal skin). Skin biopsies were also done for 25 individuals as a control group. Results: Regarding Part I of the study, no malignant skin diseases like basal cell carcinoma, squamous cell carcinoma or malignant melanoma were found in the present work. In Part II of this work, the positivity of P53 in normal skin was 32%, while in adjacent normal skin was 84% and in vitiliginous skin was 96%. Conclusions: P53 marker is over expressed in vitiligo skin and this might give it protection against skin cancers

Expression and significance of p53 and mdm2 in patients with leukoplakia cancer

ObjectiveTo study the relationship of the expressions of p53 and mdm2 in leukoplakia cancer. MethodsRT-PCR was used to detect the mRNA of p53, mdm2 in patients with leukoplakia cancer. The frequencies of p53, mdm2 in peripheral blood were detected by flow cytometric analysis. ResultsThe expression of p53mRNA in normal oral mucosa, simple oral leukoplakia, no-simple oral leukoplakia and leukoplakia cancer were 7.7%, 27.3%,33.3%, 56.8%, respectively. The frequencies of p53 in normal oral mucosa, simple oral leukoplakia, no-simple oral leukoplakia and leukoplakia cancer were (0.3±0.1)%, (1.6±0.9)%, (1.9±1.1)%, (3.4±1.8)%. The expression of mdm2 mRNA in normal oral mucosa, simple oral leukoplakia, no-simple oral leukoplakia and leukoplakia cancer were 0.0%, 6.8%, 11.1%, 37.8%, respectively. The frequencies of mdm2 in normal oral mucosa, simple oral leukoplakia, no-simple oral leukoplakia and leukoplakia cancer were (0.1±0.1)%, (0.8±0.6)%, (1.2±0.8)%, (1.2±0.8)%. There was a positively correlation between p53 mRNA and mdm2 mRNA. ConclusionsThe positive rate of p53 and mdm2 cells in the peripheral blood increases in patients with leukoplakia cancer tissue and has positive correlation with the severity of leukoplakia cancer.

P53 Codon 72 Gene Polymorphism and Risk of Oral Squamous Cell Carcinoma in South Indian Population: A Case-Control Study

Background: The p53 protein has pleiotropic functions in the modulation of genomic stability of cells. Disruption of p53 activity is commonly found in human cancers. The p53 codon 72 polymorphism is likely to play an important role in the susceptibility to OSCC. We aimed to investigate the association of p53 codon 72 polymorphism with oral squamous cell carcinoma in south Indian population. Methods: We genotyped 150 OSCC patients and 150 controls, using PCR-RFLP method. Results: Our results showed a significant difference in the distributions of p53 codon 72 genotypes among cases and controls. Genotype frequencies of p53 Arg/Arg, Arg/Pro and Pro/Pro were 50.8, 33.9 and 14.4% in the oral squamous cell carcinoma patients and 48.7, 45.1 and 6.2% in the controls, respectively. Arginine/arginine genotype was elevated in controls compared to patients (P<0.0001), where as Proline/Proline (P<0.005) and arginine/proline (P<0.002) genotypes were elevated in patients compared to controls. Arginine allele frequency showed high in cases than Proline. Conclusion: The results of the present study detected that p53 codon 72 polymorphism may contribute to oral squamous cell carcinoma susceptibility in south Indian population.

Clinical significance of P53 and Bcl-2 in acute myeloid leukemia patients of Eastern India.

The frequency of p53 and Bcl-2 protein expression in 100 newly diagnosed and 10 relapsed acute myeloid leukemia (AML) patients was analyzed by immunocytochemistry (ICC). The Kaplan-Meier method was used for univariate and multivariate statistical analysis to assess the relationship between p53, Bcl-2 and clinico-hematologic feature with respect to overall survival (OS) using SPSS statistical software. No statistical significance was found in univariate analysis (P=0.60). However, when the subgroups of patients (+1, +2, +3 and +4) were compared, expression of p53 and Bcl-2 protein (1–10%, 11–30%, 31–50% and >50%) was statistically significant (P<0.05). However, in multivariate analysis, p53, immunopositivity was independently associated with a shorter overall survival (OS) (P=0.038) while Bcl-2 immunopositivity was associated with longer overall survival (OS) (P=0.002). Our finding shows that p53 and Bcl-2 protein overexpression is a strong indicator of response to chemotherapy and overall survival. This study reports for the first time AML in patients from Eastern India.

HPV16 infection and p53 codon 72 polymorphism in cervical cancer and precursor lesions in Hubei, China.

e15582 Background: The aim of this study was to investigate the prevalence of HPV16 infection and distribution of p53 codon72 polymorphism with cervical cancer and precursor lesions and to correlate these to cervical cancer risk in Chinese population in Hubei, China. Methods: A total of 104 patients with cervical squamous-cell carcinoma (SCC) and 52 patients with cervical intraepithelial neoplasia (CIN) II-III and 88 Patients with CIN I were obtained from women undergoing biopsy or surgery. HPV16 and p53 codon72 polymorphism were examined by PCR. Results: The prevalence of HPV16 was 78.5% in the SCC group, 44.2% in the CINII- III group and 16.7% in the CIN I group. There was significantly association between HPV16 positivity and cervical neoplasia progression (Spearman R=0.550, P=0.001). The percentages of Arg/Arg, Pro/Arg and Pro/Pro genotypes in the SCC group were 38.5%, 44.2%, 17.3%, and in CIN I group were 52.4%, 40.5%, 7.1%, respectively. The RR (risk ratio) of Pro/Pro genotype was 3.300 (95% CI=1.192-9.136) compared with Arg/Arg genotype. The frequencies of p53 Arg/Arg genotype in SCC group were not statistically different from those in the CIN I and CINII- III group. The distributions of p53 codon72 genotype Arg/Arg, Arg/Pro, Pro/Pro were 32.8%, 57.1%, 14.2% in the HPV16 infected SCC group; 27.1%, 47.8%, 30.4% in the HPV16 infected CINII- III group; and 28.6%, 57.1%, 17.3% in the HPV16 infected CIN I group respectively. The distribution of p53 genotypes was not significantly different from each other in the three groups (P=0.517). The frequency of p53 Arg/Arg genotype in HPV16 negative SCC group (50%) was not statistically different from that in the HPV16 positive SCC group (P=0.210). Conclusions: The p53 codon72 Pro/Pro genotype was one of the highest risk factors of precancerous cervical lesion in Chinese population in Hubei areas.

Oncogenic Smad3 signaling induced by chronic inflammation is an early event in ulcerative colitis-associated carcinogenesis

Both chronic inflammation and somatic mutations likely contribute to the pathogenesis of ulcerative colitis (UC)-associated dysplasia and cancer. On the other hand, both tumor suppression and oncogenesis can result from transforming growth factor (TGF)-β signaling. TGF-β type I receptor (TβRI) and Ras-associated kinases differentially phosphorylate a mediator, Smad3, to become C-terminally phosphorylated Smad3 (pSmad3C), linker phosphorylated Smad3 (pSmad3L), and both C-terminally and linker phosphorylated Smad3 (pSmad3L/C). The pSmad3C/p21(WAF1) pathway transmits a cytostatic TGF-β signal, while pSmad3L and pSmad3L/C promote cell proliferation by upregulating c-Myc oncoprotein. The purpose of this study was to clarify the alteration of Smad3 signaling during UC-associated carcinogenesis. By immunostaining and immunofluorescence, we compared pSmad3C-, pSmad3L-, and pSmad3L/C-mediated signaling in colorectal specimens representing colitis, dysplasia, or cancer from eight UC patients with signaling in normal colonic crypts. We also investigated p53 expression and mutations of p53 and K-ras genes. We further sought functional meaning of the phosphorylated Smad3-mediated signaling in vitro. As enterocytes in normal crypts migrated upward toward the lumen, cytostatic pSmad3C/p21(WAF1) tended to increase, while pSmad3L/c-Myc shown by progenitor cells gradually decreased. Colitis specimens showed prominence of pSmad3L/C/c-Myc, mediated by TGF-β and tumor necrosis factor (TNF)-α, in all enterocyte nuclei throughout entire crypts. In proportion with increases in frequency of p53 and K-ras mutations during progression from dysplasia to cancer, the oncogenic pSmad3L/c-Myc pathway came to be dominant with suppression of the pSmad3C/p21(WAF1) pathway. Oncogenic Smad3 signaling, altered by chronic inflammation and eventually somatic mutations, promotes UC-associated neoplastic progression by upregulating growth-related protein.

Alterations in p53, BRCA1, ATM, PIK3CA, and HER2 genes and their effect in modifying clinicopathological characteristics and overall survival of Bulgarian patients with breast cancer

Though p53, BRCA1, ATM, PIK3CA, and HER2 genes are shown to be involved in various aspects of breast carcinogenesis, their functional relationship and clinical value are still disputable. We investigated the genetic status or expression profile of these genes to further elucidate their clinical significance. PCR-SSCP-Sequencing of p53, BRCA1, ATM, and PIK3CA was performed in 145 Bulgarian patients with sporadic breast cancer. Expression profiles of HER2 were determined by ICH and CISH. Relationship between mutations and clinicopathological characteristics was evaluated by Chi-squared and Fisher's exact tests. Multivariate Cox proportional hazard test and Kaplan-Meier analysis were used to evaluate differences in overall survival between groups. The frequency of p53 (22.07%), BRCA1 (0.69%), ATM (7.59%), and PIK3CA (31.25%) alterations and HER2 (21.21%) overexpression was estimated. Mutated p53 was associated with tumor size (P = 0.033) and grade of malignancy (P = 0.001), ATM--with grade of malignancy (P = 0.032), and PIK3CA--with PR-positive tumors (P = 0.047). HER2 overexpression correlated with age of diagnosis (P = 0.009), tumor size (P = 0.0004), and ER expression (P = 0.011). Univariate survival analysis showed that mutated p53 is an indicator for worse outcome (P = 0.041). Combination of two genetic abnormalities did not correlate with more aggressive carcinogenesis and worse overall survival. Our data indicated that p53, BRCA1, ATM, PIK3CA, and HER2 alterations specifically correlate with clinicopathological characteristics of Bulgarian patients with breast cancer. Of these genes, only mutated p53 showed significant, though not independent, negative effect on overall survival.

Genetically Distinct and Clinically Relevant Classification of Hepatocellular Carcinoma: Putative Therapeutic Targets

The biological aggressiveness of hepatocellular carcinoma (HCC) and the lack of optimal therapeutic strategies have rendered the disease a major challenge. Highly heterogeneous genetic alteration profiles of HCC have made it difficult to identify effective tailor-made molecular therapeutic targets. Therefore, classification of HCC into genetically homogeneous subclasses would be of great worth to develop novel therapeutic strategies. We clarified genome-scale chromosomal copy number alteration profiles and mutational statuses of p53 and beta-catenin in 87 HCC tumors. We investigated the possibility that HCC might be classifiable into a number of homogeneous subclasses based solely on their genetic alteration profiles. We also explored putative molecular therapeutic targets specific for each HCC subgroup. Unsupervised hierarchical cluster analysis based on chromosomal alteration profiles suggested that HCCs with heterogeneous genetic backgrounds are divisible into homogeneous subclasses that are highly associated with a range of clinicopathologic features of the tumors and moreover with clinical outcomes of the patients (P < .05). These genetically homogeneous subclasses could be characterized distinctively by pathognomonic chromosomal amplifications (eg, c-Myc-induced HCC, 6p/1q-amplified HCC, and 17q-amplified HCC). An in vitro experiment raised a possibility that Rapamycin would significantly inhibit the proliferative activities of HCCs with 17q amplification. HCC is composed of several genetically homogeneous subclasses, each of which harbors characteristic genetic alterations that can be putative tailor-made molecular therapeutic targets for HCCs with specific genetic backgrounds. Our results offer an opportunity for developing novel individualized therapeutic modalities for distinctive genome types of HCC.

Limitations in Molecular Detection of Lymph Node Micrometastasis From Colorectal Cancer

Colorectal cancer patients with lymph node metastasis have a shorter survival and may require adjuvant therapy after surgery of the primary tumor. It is supposed that a more reliable diagnosis can be achieved using tumor-specific DNA mutations for the detection of metastasizing cells. To design a practical approach for a molecular diagnosis of micrometastasis, we applied direct DNA sequencing to screen 48 early stage colorectal carcinomas for the most frequent mutations of the KRAS, P53, and APC tumor genes. KRAS mutations were detected as frequently as described earlier. In contrast, the frequency of P53 and APC hot spot mutations was unexpectedly low, compared with previous studies using other screening methods or including advanced tumor stages. Not more than 31% of early stage tumors showed a mutation in at least 1 of the selected hot spot codons. Applying mutant-enriched polymerase chain reaction (PCR), the mutation of the primary tumor was detected in lymph node DNA from 2 of the KRAS-positive patients. In 1 patient, the result was not verified by subtractive iterative PCR, a principally different molecular method with high sensitivity and specificity. Our data suggest that screening for suitable markers for a molecular detection of occult lymph node metastasis cannot be restricted to small-sized hot spot regions of a few tumor genes and possibly must include tumor-specific epigenetic changes. Furthermore, restriction enzyme-based methods such as mutant-enriched PCR are not suitable to detect any mutation with equal efficiency and they should be carefully controlled to avoid false-positive detection of marker mutations in lymph node DNA.

Mucinous carcinomas of the colorectum have distinct molecular genetic characteristics

We compared the frequency of CpG island methylation phenotype (CIMP), inactivation of APC, p53 and DCC genes and K-ras and BRAF mutations in 39 mucinous carcinomas (MC) and 34 non-mucinous carcinomas (NMC) of the colorectum with different microsatellite instability (MSI) status. The higher incidence of MSI (36% vs. 18%) was observed in MC compared with NMC. APC inactivation and K-ras mutations occurred more frequently in NMC (APC, 88%, p<0.001; K-ras, 58%, p=0.01) than in MC (APC, 24%; K-ras, 28%) regardless of MSI status. BRAF mutation occurred at a higher frequency in MC (18%, p=0.01) than in NMC (0%). However, with respect to inactivation of p53 and DCC, MSI status did matter and in both NMC and MC, more frequent inactivation of p53 and DCC was observed in MSS tumors than in MSI tumors. MSS tumors of NMC had a higher frequency of p53 (58% by IHC, p=0.03 and 83% by LOH, p=0.02) and DCC inactivation (83%, p=0.02) compared to MSI tumors of NMC (p53, 33% by IHC and 20% by LOH; DCC, 20%). MSS tumors of MC also showed a higher frequency of p53 and DCC inactivation (p53, 45% by IHC, p=0.02 and 53% by LOH, p=0.005; DCC, 82%, p=0.001) compared to MSI tumors of MC (p53, 0% by IHC and 0% for LOH; DCC, 17%). MC showed a higher frequency of CIMP compared with NMC (41% vs. 11%, p=0.01). These results indicate that mucinous carcinomas of the colorectum exhibit distinct molecular genetic characteristics and may arise from distinct pathogenic pathways.

Analysis of p53 Tumor Suppressor Gene, H-ras Protooncogene and Proliferating Cell Nuclear Antigen (PCNA) in Squamous Cell Carcinomas of HRA/Skh Mice Following Exposure to 8-Methoxypsoralen (8-MOP) and UVA Radiation (PUVA Therapy)

Treatment with 8-methoxypsoralen (8-MOP) and ultraviolet radiation (primarily UVA), called PUVA therapy, has been used to treat different chronic skin diseases but led to a significant increased risk for skin cancer. The National Toxicology Program (NTP) performed a study in mice treated with PUVA that showed a significant increase in squamous cell carcinomas of the skin. In the present study, we evaluated the protein expression of p53 and PCNA and DNA mutations of p53 and H-ras genes in both hyperplastic and neoplastic squamous cell lesions from the NTP study. By immunohistochemical staining, protein expression of both p53 and PCNA was detected in 3/16 (19%) of hyperplastic lesions and 14/17 (82%) of SCCs in groups treated with both 8-MOP and UVA. The mutation frequency of p53 in SCCs from mice administered 8-MOP plus UVA was 15/17 (88%) with a predominant distribution of mutations in exon 6 (14/15 - 93%). No H-ras mutations were detected in the hyperplastic lesions/tumors. The mutagenic effect of PUVA on the p53 tumor suppressor gene may lead to a conformational modification and inactivation of the p53 protein, which are considered critical steps in PUVA-induced skin carcinogenesis. The p53 mutational frequency and patterns from our study were different from those reported in human PUVA-type tumors.

Expression of p53 protein and proliferating cell nuclear antigen in human gestation trophoblastic disease

Objective: To study the relationship between p53 protein, proliferating cell nuclear antigen (PCNA) expression and benign or malignant gestational trophoblastic disease (MGTD). Methods: The histotomic sections of 48 patients with gestational trophoblastic disease and 24 patients of normal chorionic villi were stained using immunohistochemistry. The monoclonal antibodies were used to determine p53 protein and PCNA. Results: The frequency of p53 and PCNA positive expression were significantly different among the chorionic villi of normal pregnancy, hydratidiform mole (HM) and MGTD. But neither p53 nor PCNA has any relation with the clinical staging or metastasis of MGTD. Conclusion: Both P53 and PCNA are valuable in diagnosis of human gestational trophoblastic disease.

P53 codon 72 polymorphism and risk of gastric cancer in a Chinese population

The p53 gene plays an important role in cell cycle control in response to DNA damage, which may increase the probability of mutations that lead to carcinogenesis. The p53 codon 72 Arg right curved arrow Pro polymorphism has been suggested to be associated with risk for different kind of cancers, but the data on gastric cancer (GC) is very limited. To evaluate the association between this polymorphism and risk of GC, we performed genotype analysis by using a polymerase chain reaction-based restriction fragment length polymorphism assay in a population-based case-control study of 324 GC patients and 317 cancer-free controls in a Chinese population. The controls were frequency-matched to the cases by age, sex and smoking status. The frequency of the p53 Arg allele was 57.4% in the cases and 54.9% in the controls, and the genotype frequencies of p53 Arg/Arg, Arg/Pro, and Pro/Pro were 29.6%, 55.6%, and 14.8%, respectively, in the cases, and 29.6%, 50.5%, and 19.9%, respectively, in the controls (p=0.207). Logistic regression analysis revealed that the p53 Arg allele (Arg/Pro and Arg/Arg genotype) was associated with a borderline significantly increased risk of gastric cancer (adjusted OR=1.44, 95% CI=0.95-2.18), particularly non-cardia gastric cancer (adjusted OR=1.67, 95% CI=1.00-2.77), compared with p53 homozygous Pro allele (Pro/Pro genotype), and the risk was significantly more evident among alcohol drinkers (adjusted OR=2.85, 95% CI=1.37-5.95). While the results suggest that the p53 codon 72 polymorphism may contribute to gastric cancer susceptibility, further larger studies are needed to substantiate our findings and to explore a possible interaction between p53 codon 72 polymorphism and alcohol in the etiology of gastric cancer.

Paradoxical effects by preoperative oral low-dose tegafur administration in human gastric carcinomas: Enhanced apoptosis and increased intratumoral microvessel density

This study examined the effect of preoperative low-dose tegafur treatment in human gastric carcinomas. Among 55 patients with gastric carcinoma, 33 received an oral administration of tegafur 600 mg/body/day for 7 days before. Formalin-fixed, paraffin-embedded specimens were immunostained for Ki-67, P53, P21, CD34, Bax, VEGF, and dThdPase and also examined by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling procedure. The apoptotic index (AI), Ki-67 labeling index (KI) and intratumoral microvessel density (IMVD) were counted. Mean AI and IMVD were 3.4+/-1.60 and 126.1+/-36.56 in the treated carcinomas, and 2.3+/-0.88 and 98.0+/-44.40 in the non-treated carcinomas, both values being significantly higher in the former (P<0.05). The treatment resulted in a significant increase of mean AI in the intestinal type, in the early, and in the P53-positive carcinomas (P<0.05), while the treatment brought a significant increase of IMVD in the diffuse type, in the early and in the P53-negative carcinomas (P<0.05, respectively). No significant difference was noted on the frequency of P53, P21, BAX, VEGF and dThdPase expressions between the two groups. Ki-67 expression did not correlate with any factors. Preoperative low-dose tegafur treatment resulted in a paradoxical effect; enhanced apoptosis and increased IMVD in human gastric carcinomas.

On the origin of p53 G:C → T:A transversions in lung cancers

The high frequency of G→T transversions in the p53 gene is a distinctive feature of lung cancer patients with a smoking history and is commonly believed to reflect the direct mutagenic signature of polycyclic aromatic hydrocarbon (PAH) adducts along the gene. Using the April 2000 update of the p53 mutation database of the International Agency for Research on Cancer together with the primary literature, we confirm that the frequency of p53 G→T transversions in lung cancer of smokers is about three times higher than their frequency in lung cancer of nonsmokers and in most other smoke-unrelated cancers. In contrast, the frequency of C→A transversions, the DNA-strand mirror counterpart of G→T transversions, appears to be similar in virtually all human cancers. Along with other data, this strand bias leads us to suggest that smoking may inhibit repair of G→T primary lesions on the non-transcribed strand. As to the origin of G→T primary lesions in the p53 gene, we unexpectedly found that cell lines derived from lung cancers, but not from other cancers, demonstrate significant additional excess of G→T transversions when compared to p53 mutations in parent primary tumors. A detailed codon-by-codon comparison provides evidence in favor of the in vitro origin of this culture-associated G→T augmentation. Since in culture lung cancer cell lines are not exposed to the carcinogens from smoke, one would rather ascribe these new G→T transversions to some other mutagens such as, for example, reactive oxygen and nitrogen species. These results are consistent with our previous report [Proc. Natl. Acad. Sci. U.S.A. 97 (2000) 12244], and suggest that other factors, in addition to the direct mutagenic action of PAH-like carcinogens, contribute to p53 mutation-associated lung malignancy.

Expression of p53 and bcl-2 in Renal Cell Carcinoma

Background. Renal cell carcinoma (RCC) is often resistant to conventional chemotherapy and irradiation, which suggests that RCC cells are unable to undergo apoptosis. Both p53 and bcl-2 are involved in the regulation of apoptosis. The aims of this study were 1) to determine the relationship between p53 and bcl-2 statuses in RCC during the pathologic stage, and 2) to evaluate the roles of p53and bcl-2 in RCC metastasis. Methods. Immunohistochemical stains of p53and bcl-2 protein were performed on 34 paraffinembedded RCC specimens, from 16 patients (stage I: 8, stage II: 5and stage III: 3) who did not develop metastasis and 18 patients (stage I: 2, stage II: 6, stage Ill: 6 and stage IV: 4) who developed metastasis during follow-up. Results. Staining results positive for p53were detected in 10 (29%) of 34 RCCs and staining results positive for bcl-2 were seen in 12 (35%) of 34 RCCs. No correlations between p53frequency and disease stage or between p53 frequency and pathologic grade were detected. The metastatic group had higher incidence in p53expression than the non-metastatic group (p = 0.063), especially for clear cell type of RCCs (ρ= 0.017). The bcl-2 expression showed a significant correlation with tumor grade (p = 0.048) but not with pathological stage or metastatic potential. Staining results positive for both p53 and bcl-2 were detected in six (18%) of 34 RCCs, but there were no significant correlations between the status of tumor stage, tumor grade or metastasis. Conclusions. From our limited number of cases we concluded that patients with welldifferentiated RCC had a higher incidence of bcl-2 expression than those with moderately or poorly differentiated RCCs. For clear cell type RCCs, the metastatic group had a higher incidence of positive staining results for p53than the non-metastatic group.

P53 codon 72 polymorphism as a risk factor in the development of HPV-associated non-melanoma skin cancers in immunocompetent hosts.

Human papilloma virus (HPV) has been implicated in skin cancer. Also, in human populations, the p53 gene is polymorphic at amino acid 72 of the protein that it encodes. The association between p53 polymorphisms and HPV-associated skin cancer risk has been examined, but the results were conflicting. It was revealed that the arginine form of p53 is more susceptible to degradation by the HPV E6 protein than the proline form and that patients with the arginine form have a higher risk of developing cancer than those with the proline form. The purpose of this study was to examine whether p53 Arg at the polymorphic position 72 could represent a risk factor for patients with high risk HPV-associated malignant skin lesions. The study was conducted on 29 high risk HPV-related skin lesions from Greece. Blood samples from 61 healthy individuals were used as controls. HPV-8 was the most frequent type. There was a difference in the distribution of p53 genotypes between high risk HPV-skin lesions and the controls, and the allele frequency of p53 Arg/Arg was much higher than the controls (65.5% versus 20%). Therefore, it is suggested that p53 Arg homozygosity could represent a potential risk factor for tumorigenesis of the skin.

The frequency of p53, k-ras mutations, and microsatellite instability differs in uterine endometrioid and serous carcinoma

The two most common types of uterine endometrial carcinoma, endometrioid (UEC) and serous (USC), differ in their histopathologic appearance and biologic behavior. Recent studies suggest that these differences may be associated with distinct molecular genetic alterations. In the current study, the authors compared the frequencies of K-ras and p53 mutations and microsatellite instability (MI) between UEC and USC by analyzing all 3 molecular genetic changes in one set of tumors. Furthermore, the distribution of these molecular genetic alterations was determined among UECs of different histopathologic grade. The authors analyzed 58 UECs with known MI status for K-ras and p53 mutations. The K-ras and p53 genes were analyzed in 45 and 6 cases of USC, respectively. These results were combined with previous data on p53 mutations (21 cases) and MI (34 cases) in USC. MI was present in 16 of 57 UECs (28%) but in none of 34 USCs. p53 mutations were found in 7 of 42 UECs (17%) and 25 of 27 USCs (93%) by direct sequencing of exons 5-8. UECs and USCs with p53 mutations showed strong immunoreactivity for p53 in about 85% of the cases, whereas about 15% of the cases were immunonegative. K-ras mutations at codon 12 were found in 15 of 58 UECs (26%) and in only 1 of 45 USC (2%) by dot blot oligohybridization after polymerase chain reaction amplification of exon 1. Notably, the frequency of both K-ras and p53 mutations and MI was significantly different between UEC and USC (P < 0.001). In UECs, MI and K-ras mutations occurred in low grade as well as in high grade tumors, whereas p53 mutations were present almost exclusively in high grade tumors. The results of this study suggest that different molecular genetic pathways are involved in the pathogenesis of UEC and USC and that low grade UEC may progress to high grade UEC. These findings support the hypothesis that UEC and USC are separate entities and suggest that different molecular genetic alterations may be responsible for their distinct morphology and biologic behavior.