Molecular epidemiology of breast cancers in northern and southern Japan: the frequency, clustering, and patterns of p53 gene mutations differ among these two low-risk populations

Comparison of acquired mutations in the p53 tumor suppressor gene can illuminate factors contributing to carcinogenesis among cancer cohorts. Japan has an ethnically homogeneous population with a low incidence of breast cancer. Previously we reported an unusual frequency, allelic status, and clustering of mutations in breast cancers from the northern part of the main Japanese island. To extend these findings, exons 2-11 and adjacent intronic sequences were analysed in tumors of women from northern (Hokkaido) and southern (Tokushima) Japan. The frequency of breast cancers with p53 gene mutations in the Hokkaido group is the highest reported (81%) while that in Tokushima (28%) is similar to most other populations. Thirteen of the 19 mutations (68.4%) in the Hokkaido cohort were heterozygous, an unusually high frequency for p53 mutations in any tumor type. There were three missense mutations at codon 175, a known hotspot for alterations in the p53 gene, and three missense mutations at codon 179, a rare site for p53 changes. In addition, the patterns of p53 gene mutation differed between the two Japanese cohorts (P=0.04). The multiple differences in acquired p53 mutations suggest unsuspected biological differences among breast cancers in northern and southern Japan. In addition, the high frequency of p53 mutations in breast cancers from Hokkaido predicted a poorer prognosis for this population which was confirmed on examination of mortality data.     

P1-purinoceptor-mediated modulation of neural noradrenaline and ATP release in guinea-pig vas deferens

BACKGROUND/AIMS: Mutations in p53, a tumor suppressor gene located on chromosome 17p, are the most frequent genetic alterations found in human cancers. Increased intracellular concentration of p53, which is frequently but not systematically related to p53 mutation, has been proposed to be associated with poor prognosis in some tumor types. In colorectal cancer, this significance is still a matter of debate. To directly investigate the relationship between prognosis and p53 mutation, this study screened a series of 85 colorectal carcinomas for mutations in exons 5-8 of this gene. METHODS: Polymerase chain reaction-amplified products from tumor DNA were analyzed by denaturing gradient gel electrophoresis and direct DNA sequencing. RESULTS: Forty-four tumors were found to be mutated (52%). A strong correlation between the presence of a mutation and short survival was observed (P = 0.003). When tumors were classified according to their histological stage, a multivariate Cox model analysis showed that p53 mutation, rather than 17p allelic loss (previously proposed to convey prognostic information), was retained as the only independent prognostic factor (relative risk, 2.25; 95% confidence interval, 1.06-4.80; P < 0.029). CONCLUSIONS: Combined with staging, direct monitoring of p53 mutation improves prognostic accuracy for colorectal cancer.     

Mutations of the p53 tumor suppressor gene occur infrequently in Wilms' tumor

Mutations of the p53 tumor suppressor gene occur frequently in a variety of adult-onset tumors, including colon, breast, lung, and brain, yet are infrequently identified in pediatric malignancies. Wilms' tumor, a common solid tumor of childhood, can be associated with mutations of the WT1 gene. Alterations of the p53 gene have been shown to modulate the ability of WT1 to transactivate its targets. Although positive p53 immunostaining has been demonstrated in Wilms' tumors, the correlation to p53 gene mutations is not clear. We examined Wilms' tumor samples for p53 mutations utilizing polymerase chain reaction-single-strand conformation polymorphism analysis and single-strand DNA sequencing. Mutations in the coding region of the p53 gene were demonstrated in 2 of 21 (9.5%) Wilms' tumors. Each mutation yielded a substitution of amino acid residues. One mutation was located in exon 6 and the other in exon 7. Both mutations were found in tumors from patients with advanced stage disease. Focal anaplasia was demonstrated in one of these tumors. Our data suggest that although p53 mutations occur infrequently in Wilms' tumor, they may be associated with advanced disease.     

p53 status has no prognostic significance in glioblastomas treated with radiotherapy

Mutation of the tumor suppressor gene TP53 and accumulation of the p53 protein are common events in the range of cerebral astrocytic tumors, including glioblastomas, but it is uncertain whether these events are associated with prognosis. Evidence suggests that the response of various tumors to radiotherapy may be influenced by the status of p53 which is involved in control of the cell cycle and apoptosis. This study tests the hypothesis that p53 governs survival in patients (n = 62) with glioblastomas who have received radiotherapy. Analysis of TP53 and p53 immunohistochemistry were undertaken using standard methods. TP53 mutations were present in 27% tumors, while 50% were p53-immunopositive (LI > 3%). A strong correlation (p < 0.0001) was found between a high p53 LI (> 50%) and the presence of a mutation, but p53 status at the level of gene or protein was unrelated to survival. Radiation-induced apoptosis that is independent of p53, and the presence in glioblastomas of genetic abnormalities that are also involved in the cellular response to radiation, such as deletions and mutations of pRb, are possible explanations of this result.     

Electrical stimulation of the trigeminal nerve root for the treatment of chronic facial pain

BACKGROUND: Alterations of the p53 gene are involved in the development of diverse human malignancies, but their incidence and clinicopathologic features are still not well characterized for endometrial carcinoma. METHODS: To investigate the clinicopathologic significance of p53, mutations and loss of heterozygosity (LOH) in endometrial carcinoma in 92 patients with this disease were examined. RESULTS: Mutations of p53 were detected in 20 (22%) of the 92 patients with carcinoma, and LOH was detected in 23 (32%) of the 72 patients in whom heterozygosity of the gene was available. There was a significant correlation between the occurrence of mutation and LOH. Mutations and LOH were more frequent in patients with Grade 3 tumors than in those with Grades 1 and 2 tumors (P = 0.0498, P = 0.0051, respectively). Patients with LOH had a poorer postoperative survival than those without LOH (P = 0.0022, log-rank test), and patients with both LOH and mutation showed the worst prognosis (P < 0.0001, log rank test). Loss of heterozygosity of the p53 gene showed a significant relation to prognosis that was independent of tumor stage, histologic grade, and muscular invasion. CONCLUSIONS: Mutation and LOH of the p53 gene are prognostic indicators in patients with endometrial carcinoma, suggesting that alterations of p53 may play an important role in the development of this cancer.     

Scoring prevalence and severity in gonarthritis: the suitability of the Kellgren & Lawrence scale

OBJECTIVES: Infection with the high-risk strain of human papillomaviruses (HPVs) and the inactivation of the tumor suppressor gene p53 through mutation are important factors in cervical carcinogenesis. To know whether such events would occur in cervical carcinomas of Indians, 43 tumors (consisting of 36 of stage III B and 6 of stage II B) were screened for p53 and p16 gene mutations. METHODS: PCR followed by single-strand conformation polymorphism (SSCP) analysis were used to detect mutations in p53 and p16 genes and PCR for the presence of human papillomavirus genome. HPV status was ascertained by PCR amplification of parts of E6 and E7 genes using primers pU-1M and pU-2R and typing was carried out by restriction analysis. RESULTS: Of the 43 samples analyzed, 4 samples (9%) showed mobility shifts for p53 mutations; PCR products of the p16 gene did not show band shifts in SSCP analysis. HPV DNA was detected in 70% of the 43 samples analyzed: HPV 16 in 23 cases (53%), HPV 18 in 4 cases (13.3%), and HPV 33 in 1 case (3.3%). Two amplified HPV DNAs that were difficult to type with various restriction enzymes were cloned and the amplified regions were sequenced. One of these was 93% close to HPV 35 and the other was 80% close to HPV 58. Three samples had both p53 mutations and HPV genome. CONCLUSIONS: Our results indicate that HPV 16 infection was more common than HPV 18, the p53 mutations and HPV infection were not mutually exclusive events in the genesis of carcinoma of uterine cervix among Indian women, and p16 gene may not play a role in Indian cervical carcinomas.     

Augmentation of the affinity of HLA class I-binding peptides lacking primary anchor residues by manipulation of the secondary anchor residues

The p53 tumor suppressor gene has been found to be altered in almost all human solid tumors, whereas K-ras gene mutations have been observed in a limited number of human cancers (adenocarcinoma of colon, pancreas, and lung). Studies of mutational inactivation for both genes in the same patient's sample on non-small-cell lung cancer have been limited. In an effort to perform such an analysis, we developed and compared methods (for the mutational detection of p53 and K-ras gene) that represent a modified and universal protocol, in terms of DNA extraction, polymerase chain reaction (PCR) amplification, and nonradioisotopic PCR-single-strand conformation polymorphism (PCR-SSCP) analysis, which is readily applicable to either formalin-fixed, paraffin-embedded tissues or frozen tumor specimens. We applied this method to the evaluation of p53 (exons 5-8) and K-ras (codon 12 and 13) gene mutations in 55 cases of non-small-cell lung cancer. The mutational status in the p53 gene was evaluated by radioisotopic PCR-SSCP and compared with PCR-SSCP utilizing our standardized nonradioisotopic detection system using a single 6-microns tissue section. The mutational patterns observed by PCR-SSCP were subsequently confirmed by PCR-DNA sequencing. The mutational status in the K-ras gene was similarly evaluated by PCR-SSCP, and the specific mutation was confirmed by Southern slot-blot hybridization using 32P-labeled sequence-specific oligonucleotide probes for codons 12 and 13. Mutational changes in K-ras (codon 12) were found in 10 of 55 (18%) of non-small-cell lung cancers. Whereas adenocarcinoma showed K-ras mutation in 33% of the cases at codon 12, only one mutation was found at codon 13. As expected, squamous cell carcinoma samples (25 cases) did not show K-ras mutations. Mutations at exons 5-8 of the p53 gene were documented in 19 of 55 (34.5%) cases. Ten of the 19 mutations were single nucleotide point mutations, leading to amino acid substitution. Six showed insertional mutation, and three showed deletion mutations. Only three samples showed mutations of both K-ras and p53 genes. We conclude that although K-ras and p53 gene mutations are frequent in non-small-cell lung cancer, mutations of both genes in the same patient's samples are not common. We also conclude that this universal nonradioisotopic method is superior to other similar methods and is readily applicable to the rapid screening of large numbers of formalin-fixed, paraffin-embedded or frozen samples for the mutational analysis of multiple genes.     

Analysis of p53 gene mutation by polymerase chain reaction-single strand conformation polymorphism provides independent prognostic information in node-negative breast cancer

Controversy continues regarding the prognostic utility of detection of p53 gene abnormalities in node-negative breast cancer. To resolve this, we used a rapid and nonisotopic PCR-single strand conformation polymorphism method to screen for mutations in exons 4-8 of the p53 gene in primary tumors from 422 node-negative breast cancer patients. The prevalence of p53 mutation in the exons tested was 18%. p53 mutation was significantly associated with several markers of poor prognosis including larger tumor size, high tumor grade, low hormone receptor content, increased expression of MIB-1 (Ki-67), amplification of the HER-2/neu oncogene, and accumulation of the p53 protein. After a median duration follow-up period of 74 months, the parameters of tumor diameter > or =20 mm, HER-2/neu oncogene amplification, and p53 mutation were found to be associated with a statistically significant shortened duration of disease-free and overall survival, but not the parameters of tumor grade, hormone receptor levels, or p53 expression. The poor prognosis associated with p53 mutation was observed primarily in patients with a tumor diameter of > or =20 mm. In multivariate analysis, p53 mutation was a risk factor for increased risk of recurrence and death from breast cancer independent of tumor size, hormone receptor levels, HER-2/neu amplification, and MIB-1 expression. We conclude that a relatively simple and rapid single strand conformation polymorphism method of determining p53 mutation status in node-negative breast cancers can provide independent prognostic information.     

p53 gene alternation in squamous cell carcinoma of the esophagus detected by PCR-cold SSCP analysis

Mutations of the p53 tumor suppressor gene play an important role in the development of common human malignancies. Previous reports revealed that the frequencies of p53 alternations in esophageal carcinoma varied from 26% to 87%. The clinical significance of p53 alternations is still disputed. In the present study, we used polymerase chain reaction--"cold" single-strand conformation polymorphism (PCR-"cold" SSCP)--to investigate p53 genetic alternations in 63 surgical specimens of esophageal squamous cell carcinoma (ESC). Our experiments showed that the optimum buffer temperature for "cold" SSCP analysis was 14 degrees C while the PCR products were around 200-300 bp in size. Among 63 tumorous samples, p53 alternations was detected in 47 tumors, or an incidence rate of 74.6%. For nontumorous mucosal samples, the incidence of p53 alternations was 55.5% (35/63 samples). Additionally, p53 alternations occurred most frequently at exon 6 (50.8%), followed by exon 7 (33.3%), exon 8 (17.5%) and exon 5 (12.7%). Multiple genetic alternations (> or = 2 exons) between p53 exons 5-8 in the same examined samples were found in 21 (33.3%) of 63 tumors, and in 8 (12.7%) of 63 nontumorous mucosal specimens. Our results further showed that p53 alternations did not correlate with age, depth of tumor invasion, lymph node metastasis, tumor stage, cell differentiation or lymphovascular invasion in ESC (P > 0.05). Moreover, the survival rate in patients with p53 alternations was similar to that in patients without p53 alternations (P > 0.05). In conclusion, PCR-"cold" SSCP is a rapid and sensitive method for identifying p53 genetic alternations. p53 genetic alternations occur with a relatively high incidence for ESC, but p53 abnormality has no impact on prognosis.     

Overexpression of the c-myc proto-oncogene in colorectal carcinoma is associated with a reduced mortality that is abrogated by point mutation of the p53 tumor suppressor gene

The survival of 119 colorectal cancer patients was analyzed in the light of the overexpression status of the c-myc proto-oncogene mRNA and the point mutation status of the p53 tumor suppressor gene in the primary adenocarcinoma. The presence of >3 fold overexpression of c-myc mRNA in the primary tumor was found to be associated with a better prognosis than patients who evinced no overexpression (P = 0.02, log rank analysis). Point mutation of the p53 tumor suppressor gene was found to be associated with a poorer patient prognosis (P = 0.007, log rank analysis). Endogenous levels of c-myc and point mutation of p53 both contributed independently toward a poorer patient prognosis in Cox regression modeling. The better prognosis seen in patients who overexpress c-myc was offset when c-myc overexpression was coupled with a point mutated p53 gene. These results suggest that in colorectal adenocarcinoma c-myc deregulation leads to increased apoptotic death, but that this response may be modulated by a more downstream event such as point mutation of the p53 gene.     

Clonal analysis of bilateral breast cancer

Forty-nine pairs of bilateral breast tumors (41 synchronous and 8 asynchronous cases) were examined for X-chromosome inactivation status and p53 mutations to address the issue of their clonality. Among 12 cases that were informative for the trinucleotide repeat polymorphism in exon 1 of the androgen receptor gene on the X chromosome, 3 cases were found to have different alleles of the locus inactivated in the right and left breast tumors, indicating that the two tumors arose from distinct transformed cells. Thirteen tumors (13%) from 11 women (22%) contained somatic mutations in exons 5-8 of the p53 gene. In two cases, both breast tumors harbored p53 mutations, but the specific mutations were not identical. Seven synchronous and two asynchronous cases had p53 mutations in one tumor only. A germ line p53 mutation at codon 248, one of the most common p53 mutations in Li-Fraumeni syndrome, was observed in one case. Immunohistochemical analysis of p53 protein with a monoclonal antihuman p53 antibody showed concordant positivity between the right and left tumors in three bilateral breast cancer cases. Our results suggest that at least some bilateral breast tumors originate from distinct cells, but that some bilateral breast tumors may be related through a common p53 abnormality.     

Correlation between mutation in P53, p53 expression, cytogenetics, histologic type, and survival in patients with B-cell non-Hodgkin's lymphoma

In the biology of a cell, the central role of p53 in controlling functions such as G1/S transition (check point) and DNA damage repair, and as a trigger of apoptosis, is well established. Somatic mutations or other changes in P53 have been reported in numerous tumor types, and in some of these, they are associated with poor prognosis. In this study, we examined 237 cytogenetically characterized B-cell non-Hodgkin's lymphomas (B-NHLs) for somatic changes in P53 by Southern blot analysis, by single-strand conformation polymorphism analysis (SSCP) of exon 5 through 9, and by direct sequencing of SSCP variants to determine the frequency and types of mutations and their clinical significance. In a portion of these (173 tumors), we also studied p53 expression by immunostaining. On Southern blots, no gross change was identified in P53 and no mutation was identified in exon 9. In exons 5 through 8, 27 different mutations were identified in 25 patients (23 single-base substitutions, 3 deletions, 1 duplication). Mutations in P53 were identified in 25 of 237 tumors (10.5%), which included 1 of 45 small lymphocytic lymphomas (SLLs), 2 of 38 follicular small cleaved-cell lymphomas (FSCCs), 2 of 35 follicular mixed small cleaved-cell and large-cell lymphomas (FMxs), 1 of 4 follicular large-cell lymphomas (FLCs), 1 of 14 diffuse small cleaved-cell lymphomas (DSCCs), 2 of 17 diffuse mixed small- and large-cell lymphomas (DMxs), and 16 of 84 diffuse large-cell lymphomas (DLCCs); the difference between the histologic groups was significant (P < .01). Among mantle-cell lymphoma (MC) patients, 3 of 10 had mutations. In 16 patients, the mutation was identified in specimens obtained at diagnosis. Mutation of transition type and transversion type occurred at a relative frequency of 2:1. Thirty percent occurred at CpG dinucleotide sequences and the codon for arginine was most frequently affected. Nineteen of 99 tumors with complex cytogenetic abnormalities, but none of 69 tumors with simple cytogenetic abnormalities, had mutations (P < .001). Similarly, 11 of 25 tumors with an abnormality of 17p and 8 of 143 tumors with apparently normal 17p had mutations (P < .0001). Positive correlations were found between a mutation and p53 expression (P < .001), between missense type mutations and p53 expression (P < .005), and between 17p abnormalities and p53 expression (P < .05). Twenty-two of 49 patients without mutation and 14 of 17 patients with mutations died (P < .05), but there was no significant difference in median survival. Similarly, 21 of 26 p53 positive patients died, whereas only 1 of 24 p53-negative patients died on-study (P < .001). Among p53-negative patients, mutation (P < .01) was positively associated with a fatal outcome. These findings indicate that in B-NHL, somatic changes in P53 were present in diagnostic specimens of all histologic types, but at a higher frequency in DLC and MC tumors. P53 mutation and/or expression has a negative influence on survival, and therefore can serve as prognostic indicators. Immunostaining for p53 is an effective way to screen for P53 changes in these tumors.     

p53 alterations are associated with improved prognosis in distal colonic carcinomas

Alterations of the p53 gene and the p53 protein are common in a wide spectrum of human malignancies. In several tumor types, p53 gene mutation and/or p53 protein overexpression correlate with a more clinically aggressive phenotype as judged by worse patient survival. This has not been clearly demonstrated to be the case in colorectal cancer. Herein, we report results of the prognostic significance of p53 protein accumulation and gene mutation in a large series of colorectal cancers (n = 541) with long patient follow-up (mean, 87 months). The large majority of patients (95%) received no postoperative systemic adjuvant therapy. The incidence of p53 accumulation detected by immunohistochemistry with the monoclonal antibody DO-7 was 30%, whereas the incidence of p53 gene mutation in exons 5-8 detected using PCR-single strand conformation polymorphism was 36%. Accumulation of p53 protein was associated with improved patient survival independent of tumor stage or grade (hazard ratio, 0.66; 95% confidence interval, 0.47-0.93; P = 0.017). A marked difference was observed depending on the location of the tumor: tumors originating in the distal colon showed a strong association between the presence of p53 accumulation and improved patient survival (P = 0.003), but this was not the case for those located in the proximal colon. Dukes' stage C tumors, but not stage B, also showed an association between p53 accumulation and better outcome (P = 0.013). Mutation of the p53 gene was associated with a trend toward improved survival, particularly in the distal tumors. Our results demonstrate that in some tumor types, the presence of p53 abnormalities can correlate with better prognosis.     

Reactive oxygen species enhances the induction of inducible nitric oxide synthase by sphingomyelinase in RAW264.7 cells

In a consecutive series of 222 colorectal carcinomas from patients with a median follow-up time of 56.8 months (range, 0.5-92.2) treated with surgery, the TP53 gene was screened for mutations. Exons 5-8 were analyzed using constant denaturant gel electrophoresis followed by sequencing, and mutations were found in 102 cases (45.9%). Mutations were found more frequently in rectal tumors versus other locations (P = 0.029) and in aneuploid compared to diploid tumors (P < 0.001). Presence of a TP53 mutation was also significantly associated with absence of microsatellite instability (P = 0.028), as well as with loss of heterozygosity at 17p13 (P < 0.001). The TP53 mutations in the left-sided and rectal tumors were more often transversions than transitions, indicating a different etiology in the development of these tumors. The tendency for shorter cancer-related survival among patients with mutations in their tumors was only statistically significant for patients with left-sided tumors (P = 0.003). All patients with mutations affecting the L3 domain of the protein involved in zinc binding had a significantly shorter cancer-related survival (P = 0.036), indicating that mutations affecting this domain have biological relevance in terms of colorectal cancer disease course. These results suggest that knowledge of a patient's TP53 status, with respect to both the presence and the localization of the mutation, may be important in prognosis evaluation, particularly when selecting patients for more aggressive postoperative therapeutic intervention.     

p53 tumor suppressor gene status and the degree of genomic instability in sporadic colorectal cancers

BACKGROUND: Genomic instability reflects the propensity and the susceptibility of the genome to acquire multiple alterations and, in turn, is believed to be a driving force behind multistep carcinogenesis. Although the molecular basis of genomic instability in sporadic colorectal cancers remains largely a mystery, mutation of the p53 tumor suppressor gene (also known as TP53) has been proposed to play an integral role in this process. However, a dilemma exists in that p53 mutation appears to be a late event in the progression of sporadic colorectal tumors, whereas genomic instability, serving as a facilitator of tumor progression, is envisioned as occurring early in this process. PURPOSE: We evaluated the relationship between p53 mutation and the major form of genomic instability in sporadic colorectal tumors, namely, that involving DNA breakage, which leads to chromosomal translocations, insertions, deletions, and gene amplification. METHODS: Fifty-eight sporadic colorectal tumors that had been previously evaluated for genomic instability were analyzed for p53 mutations. These tumors were from consecutively diagnosed patients. Genomic instability was quantified by use of inter-simple sequence repeat polymerase chain reaction analysis that employed (CA)8RG and (CA)8RY primers (R = purine [A or G]; Y = pyrimidine [C or T]); a genomic instability index (a measure of the number of alterations in tumor DNA in comparison with normal DNA, expressed as a percent) was calculated for each tumor. Mutation of the p53 gene in exons 5-9 was determined by use of single-strand conformational polymorphism-polymerase chain reaction analysis and DNA sequencing. Chi-squared analysis was used to determine the statistical significance of differences between groups of tumors. Reported P values are two-sided. RESULTS: p53 mutations were identified in 29 (50%) of the 58 tumors. The median genomic instability index value was 3.3%. Nineteen (65.5%) of the 29 tumors with p53 mutations had genomic instability indices that were less than the median value (range, 0%-2.6%); the remaining 10 (34.5%) tumors had genomic instability indices that were greater than the median (range, 3.9%-13.0%). Eleven (37.9%) of the 29 tumors with wild-type p53 genes had genomic instability indices that were less than the median value (range, 0%-2.6%), whereas the remaining 18 tumors had genomic instability indices above the median (range, 3.9%-11.7%). There was a statistically significant association between a lesser degree of genomic instability and the presence of p53 mutations (P = .032). CONCLUSIONS AND IMPLICATIONS: Tumors with no or minimal evidence of genomic instability are more likely to harbor p53 mutations than tumors with evidence of substantial genomic instability. p53 mutations play an important role in the development of cancers but do not appear to initiate or promote genomic instability in sporadic colorectal tumors.     

Racial disparity in the association of p53 gene alterations with breast cancer survival

A significant black/white difference in breast cancer prognosis has been observed in the United States. Alterations of p53 tumor suppressor gene in breast cancer have been associated with poor prognosis. This study was designed to test the hypothesis that p53 gene alterations are related to the difference in prognosis between black and white breast cancer patients. Formalin-fixed paraffin-embedded breast tissue blocks were available from 45 black and 47 white patients for PCR-single strand conformation polymorphism analysis and DNA sequencing. The types of p53 gene alterations were compared between blacks and whites. Associations between p53 gene alterations and survival were also evaluated. Three missense, 2 nonsense, 1 microdeletion, 1 intron, and 4 silent mutations were detected in blacks, while 7 missense, 1 microdeletion, 1 silent mutation, and 3 polymorphisms were observed in whites. Among the point mutations, G:C to A:T transitions at non-CpG sites were found in 80.0% of blacks (8 of 10) and 62.5% of whites (5 of 8). Significantly poorer survival associated with p53 gene alterations was observed for blacks (P = 0.012), but not for whites. Black patients with p53 alterations had a significant 4-5-fold excess risk of death from breast cancer than those without p53 alterations. Adjustment for stage, age, tumor histopathology, receptor status, and adjuvant treatment did not change the excess risk. The findings suggest that the types of p53 gene alterations may contribute to the racial difference in breast cancer survival.     

Managing HIV. Part 8: Controlling an epidemic. 8.3 Prospects for a preventive HIV vaccine

Immunohistochemistry and in situ hybridization techniques were used to investigate the correlation between p53 gene mutation and the clinico-pathological status as well as prognosis of large cell carcinoma of the lung. p53 expression was found in 40% of the cases by immunohistochemistry and p53 gene mutation was found in 53.3% by in situ hybridization. The concordance ratio was 73.3% between gene mutation and protein expression. No statistically significant correlation was found between p53 gene mutation, its protein expression and sex, age, smoking, histological type, tumor size or lymph node involvement. A significant correlation was found between p53 gene mutation (or its protein expression) and mitotic index. The result of in situ hybridization demonstrated that there was a statistically significant correlation between p53 gene mutation and a poor prognosis. It was found that p53 gene mutation was associated with fast growth of the tumor. Therefore p53 gene mutation is probably an indicator of poor prognosis for large cell carcinoma of the lung.     

Fibronectin synthesis by human tubular epithelial cells in culture: effects of PDGF and TGF-beta on synthesis and splicing

Mutations of p53 tumor suppressor gene are the most common genetic alterations in a variety of human carcinomas. The sites of p53 mutations, however, vary in different cancers. The present study was designed to characterize p53 mutations in 40 primary human renal cancer specimens using hot-start-PCR-single-strand conformation polymorphism (SSCP) analysis, sequencing of PCR product and immunohistochemistry. DNA extracted from microdissected paraffin-embedded sections was amplified by hot-start-PCR using oligonucleotide primers specific for exons 4-9 of p53. The mutations were analyzed by PCR-SSCP technique and the generated fragments were denatured and analyzed by 6% polyacrylamide gel electrophoresis. The samples showing a band shift were denatured and sequenced using the Sequenase Version 2.0 DNA Sequencing Kit (US Biochemical, Cleveland, Ohio). Genomic DNA from control samples containing wild-type p53 alleles was sequenced in parallel for confirming mutations in samples that were positive for p53 in the PCR-SSCP analysis. The results of these experiments demonstrate that: (1) there were mutations in p53 exon 5 and 8 in 35% (14 out of 40 samples) of human renal cancer tissues as revealed by PCR-SSCP analysis; (2) DNA sequencing of samples showing frame-shift have hot spot of p53 mutation on exon 8 at codon 244 (GGC-->TGC) and exon 5 at codon 132 [AAG (Lys)-->AGG (Arg)]. This mutation in p53 exon 5 at codon 132 is novel and has not yet been reported; (3) immunohistochemical staining of p53 in renal cancer tissue using mouse anti-human p53 monoclonal antibody, clone PAb 1801, correlated with the p53 mutation assessed by PCR-SSCP. No correlation was found between p53 mutations and tumor stage and grade of renal cancer.