Analysis Of P53 Gene Mutations Research Articles

Mutational analysis of p53 gene in cervical cancer and useful polymorphic variants in exons 3 and 4

BackgroundFactors contributing to the pathogenesis and progression of cervical cancer include poor attitude to screening and health intervention, late presentation, among others. Mutations in p53 gene have been attributed to several cancer cases. The present study was designed to find relationships between the mutation patterns in p53 gene and cervical carcinoma staging. Such knowledge could contribute to early diagnosis of cervical cancer.ResultsFrom the sequence analysis of p53 gene fragment isolated by polymerase chain reactions (PCR), nineteen (19) polymorphic variants were identified. Missense mutations occurred in 47% of the samples, 32% were silent mutations, 16% were frameshift mutations and 5% nonsense mutations. Socio-biological characteristics of the study participants revealed that 60% have husbands with multiple sexual partners and that only 23.3% of the participants have ever had the Papanicolaou (Pap) smear test prior to diagnosis, whilst 20% were unaware of the screening test.ConclusionsIncreased severity of cervical carcinoma staging as revealed from the histopathological analysis was found to be associated with accumulation of higher levels of mutations in the p53 gene. Molecular analysis of p53 gene mutations may prove useful as a screening biomarker for cervical cancer.

Discrimination of p53 immunohistochemistry-positive tumors by its staining pattern in gastric cancer.

Immunohistochemistry staining of p53 is a cheap and simple method to detect aberrant function of p53. However, there are some discrepancies between the result of immunohistochemistry staining and mutation analysis. This study attempted to find a new definition of p53 staining by its staining pattern. Immunohistochemistry staining of p53 and TP53 gene mutation analysis were performed in 148 gastric cancer patients. Also SNP-CGH array analysis was conducted to four cases. Positive staining of p53 was observed in 88 (59.5%) tumors. Tumors with positive p53 staining showed malignant features compared to negative tumors. Mutation of TP53 gene was observed in 29 (19.6%) tumors with higher age and differentiated type. In positive p53 tumors, two types could be distinguished; aberrant type and scattered type. With comparison to TP53 gene mutation analysis, all the scattered type had wild-type TP53 gene (P = 0.0003). SNP-CGH array showed that scattered-type tumors had no change in the structure of chromosome 17. P53-scattered-type staining tumors may reflect a functionally active nonmutated TP53 gene. In interpretation of p53 immunohistochemistry staining, distinguishing p53-positive tumors by their staining pattern may be important in gastric cancer.

THE Analysis of CEBPA, NPM1, FLT3 and P53 gene mutations in groups of patients with myelodysplastic syndrome and acute nonlymphocytic leukaemia

The article presents the molecular genetic analysis of the prevalence of somatic mutations in FLT3, NPM1, CEBPA, and p53 genes in a group consisting of 23 patients with myelodysplastic syndrome MDS (option - refractory anemia with excess blasts, RAEB) and 97 patients with acute nonlymphoblastic leukemia (ANLL). It was ascertained that FLT3-ITD mutations in the group of patients with MDS RAEB occur with the prevalence of 8,7 ± 5,9 %, while in the group with ANLL they are observed in 22,7 ± 4,3 % cases. FLT3 D835 mutations were detected only in the ANLL group with the prevalence of 7.2±2.6 %. NPM1 gene mutations were detected in 8,7 ± 5,9 % of MDS RAEB cases and in 21,6 ± 4,2 % of ANLL cases. CEBPA somatic mutations were found in 11,3 ± 3,2 % of ANLL cases, while the group of MDS RAEB was free of them. Mutations in the p53 gene were detected in 17,4 ± 7,9 % of MDS RAEB cases and in 10,3 ± 0,3 % of ANLL cases. All the detected CEBPA and p53 gene mutations were described by means of direct sequencing. The analysis results show that the use of molecular genetic markers in combination with cytogenetic ones makes it possible to expand the group with prognostic markers by 41,3 % in comparison with the use of only cytogenetic data.

Comparative Analysis of p53 and K-ras Gene Mutations in Gastric Cancer Tissue

Mutations of p53 and K-ras gene have been proven to play important roles in human tumor progression. Point mutations of p53 gene located in codon 282 and K-ras gene located in codons 61 are both gene hot spot mutation regions in patients with gastric cancer. The polymerase chain reaction (PCR) fragments included codon 282 of p53 and codon 61 of K-ras gene. The PCR fragments were analyzed by single-strand conformation polymorphism (SSCP) combined with CE and polyacrylamide gel electrophoresis (PAGE). Forty-two gastric cancer patients were analyzed using two developed method. P53 gene mutation was found in 24 cases (57.2 %) and K-ras were 17 cases (40.5 %). The results showed that p53 and K-ras gene mutation in gastric cancer tissue is a usual event, and the SSCP-CE was feasible for mutation detection of p53 and K-ras gene in populations. Combined detection of p53 and K-ras gene mutations of gastric cancer tissue by PCR-SSCP has a certain value to diagnosis of gastric cancer.

Identification of spliced variants of the proto‐oncogene hdm2 in colorectal cancer

The human double minute 2 (hdm2) oncogene is a negative regulator of the p53 gene. Expression and alternative splicing of the hdm2 gene may contribute to colorectal cancer development or progression. This study aimed to determine the presence and identification of aberrant mRNA transcripts of hdm2 in colorectal cancer tissues and cell lines, and determine the nature of their association with clinicopathological characteristics and survival of patients. A total of 69 colorectal cancer and corresponding normal tissue specimens and 10 colon cancer cell lines were recruited for polymerase chain reaction and DNA sequencing analyses of hdm2 mRNA. Genomic DNA from these tissues and cells was also extracted for p53 gene mutation analysis. The association of hdm2 fragmented transcripts and p53 gene mutation with clinicopathological data was then statistically analyzed. In 62 cases (89.9%; 62 of 69) of colorectal cancer tissues the full-length hdm2 was amplified, whereas 7 cases had no hdm2 transcripts. Thirty-two of 62 cases (51.6%) and 6 of 10 cell lines (60%) showed at least 1 hdm2 spliced variant. A total of 4 hdm2 splicing variants were found in colorectal cancer tissues and cells, that is, lack of nucleotides between 157 and 292 bp in hdm2/1338, 81 to 901 bp in hdm2/707, 157 to 292, 407 to 505, and 668 to 901 bp in hdm2/1007, and 610 to 883 in hdm2/1200. Of these, hdm2/1338 is a novel hdm2 variant in colorectal cancer. Mutation in p53 was detected in 21 cases (33.8%; 21 of 62). Although there was no association found between expression of hdm2 splicing variants and p53 gene mutations, expression of hdm2 splicing variants was associated with advanced tumor stage (P = .022) and distant metastasis (P = .004) in wild-type p53 cases, and with poor survival of patients (P = .039). The data from the current study provide the first evidence that hdm2 mRNA is frequently mutated by alternative splicing in colorectal cancer, and may play a role in colorectal tumorigenesis or cancer progression.

Colon Cancer Arising in an Ulcer Scar due to Intestinal Behcet's Disease

Neoplasms rarely arise in the intestinal lesion of Behçet's disease. We present a 77-year-old man with Behçet's disease who developed colon cancer in the ileocecal region. Ileocecal resection was performed and pathological examination of the specimen revealed advanced colon carcinoma (pT3, N1, M0). The lesion was associated with destroyed tunica muscularis and severe fibrosis suggesting a transmural ulcer scar (Ul-IVs). The p53 gene mutation analysis of the tumor showed a heterozygous deletion. This case indicates there is a possibility that cancer may develop in intestinal lesions of patients with Behçet's disease as well as in those with other inflammatory bowel diseases.

EGFR, K-ras, p53 Gene Mutation Analysis in Non-small Cell Lung Cancer Using Microsamples Obtained by Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration

PURPOSE: The importance of biomarker analysis in patients with lung cancer is well known and we have previously reported the usefulness of endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) for biomarker assessment as well as pathological diagnosis. The purpose of this study was to analyze the multiple gene mutation status in samples obtained by EBUS-TBNA and to examine the correlation between treatments and outcomes.

Diagnosis of primary versus metastatic ovarian adenocarcinoma using p53 gene mutation analysis

Distinguishing primary ovarian cancer from metastatic colorectal cancer is often difficult by a conventional pathological examination alone. We assessed the usefulness of p53 gene mutation analysis for the differential diagnosis of ovarian adenocarcinoma. A 66-year-old woman suffered multiple organ metastases, including the liver, para-aortic lymph node, and right ovary, following an operation for advanced sigmoid colon cancer. She underwent ovarian resection after effective chemotherapy against the liver and para-aortic lymph node cancer. Histological analysis suggested primary ovarian cancer. Therefore, we applied p53 gene mutation analysis for the differential diagnosis of primary versus metastatic ovarian cancer from sigmoid colon cancer. The direct sequence of the p53 gene demonstrated the same gene mutation in codon 211 (ACT to ATT) in both the sigmoid colon and ovarian cancers. According to the International Agency for Research on Cancer TP53 mutation database, this type of p53 mutation in colorectal cancer and ovarian cancer is 0.13% (5/3,693) and 0% (0/1,494), respectively. Therefore, we determined that the ovarian tumor was metastatic. Although p53 gene mutation analysis has been applied in some cases, this modality is very useful for the differential diagnosis of primary and metastatic cancer.

Malignant epithelioid angiomyolipoma of the kidney in a patient with tuberous sclerosis: An autopsy case report with p53 gene mutation analysis

We report an autopsy case of malignant epithelioid angiomyolipoma in a 36-year-old male tuberous sclerosis patient. He had been diagnosed to have a bilateral renal tumor 20 years previously. The left kidney had been surgically resected at the age of 34, and the left renal tumor was pathologically diagnosed as classic angiomyolipoma and epithelioid angiomyolipoma. He suddenly died of cardiac arrest, and at autopsy the right kidney weighed 7120 g. The tumor presented with massive necrosis invading the inferior vena cava, but was not hemorrhagic. Microscopic examination revealed tumor cells varying in size with a predominantly solid proliferation pattern and marked atypical large cells with vesicular nuclei and abundant eosinophilic cytoplasm. Mitotic figures were often encountered, and atypical forms were also present. Metastatic lesions were identified in the right lung, liver, diaphragm, and mesentery. Immunohistochemical examination showed epithelioid angiomyolipoma cells that were focally reactive for HMB-45 and showed diffuse positive staining for Melan-A. No mutation was detected in the p53 gene by polymerase chain reaction–single-strand conformation polymorphism (PCR–SSCP) analysis despite diffuse immunoreactivity for p53. This case was proven to be malignant because of the occurrence of distant metastases, and showed that p53 mutations are not always associated with malignant transformation in epithelioid angiomyolipoma.

Intraperitoneal dedifferentiated liposarcoma: A case report

Dedifferentiated liposarcoma is a variant of liposarcoma with a more aggressive course. Mutations of the p53 gene have been found in different types of soft tissue sarcoma. It is generally accepted that p53 mutations in human malignant tumors are often related to a poor prognosis. In our case, analysis of p53 gene mutation in tumor samples was performed. p53 gene mutation was observed in dedifferentiated tumor tissue samples but not in well-differentiated tumor tissue samples. It has been reported that p53 gene mutation occurs most commonly in the retroperitoneum and rarely in other anatomic locations. Herein we report a case of dedifferentiated liposarcoma located at intraperitoneum.

Immunohistochemical evaluation of p53 expression with different antibodies in malignant canine tumours with or without p53 gene mutation

Six monoclonal antibodies and a polyclonal antibody (CM1) were used to investigate the overexpression of p53 protein by immunohistochemistry (IHC) in six sarcomas and 21 mammary carcinomas from 27 dogs. IHC was compared with p53 gene mutation analysis performed on the same samples. Only the monoclonal PAb240, PAb421 and the CM1 antibodies were able to detect expression of canine p53 protein. CM1 was found to give the highest concordance (8/11) between positive expression of the p53 protein by IHC and the presence of a gene mutation. In the samples that were negative for p53 expression by IHC, but contained a p53 gene mutation according to DNA analysis, the mutation often affected the epitopes that could have been recognized by these antibodies. Only one out of 16 tumours without a p53 gene mutation had a weakly positive IHC result. These findings indicate that in these two types of canine tumours, IHC - particularly with CM1 - can detect many alterations in p53 expression owing to a gene mutation. False-positive results were very infrequent.

Analysis of p53 and K-Ras Gene Mutations in Patients with Chronic Bronchitis Using Laser Capture Microdissection Microscope and Mutation Detection

Analysis of p53 and K-Ras Gene Mutations in Patients with Chronic Bronchitis Using Laser Capture Microdissection Microscope and Mutation Detection

Analysis of p53 and Bak gene mutations in lymphoproliferative disorders developing in rheumatoid arthritis

Individuals affected by rheumatoid arthritis (RA) occasionally develop lymphoproliferative disorders (RA-LPD). To study the molecular changes underscoring the RA-LPD, mutations of p53 and Bak gene were analyzed in RA-LPD with (MTX-LPD) or without methotrexate treatment for RA (non-MTX-LPD). Histology and immunophenotype were immunohistochemically examined in 32 cases of MTX-LPD and 21 of non-MTX-LPD. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing was employed to detect the mutations of p53 and Bak gene. Frequency of p53 mutations in non-MTX-LPD (47.6%) was significantly higher than that in MTX-LPD (15.6%) (P < 0.05). Among the cases with non-Hodgkin's lymphoma (NHL), the largest category of RA-LPD, the frequency of p53 mutations in the non-MTX-NHL (47.6%) was significantly higher than that in the MTX-NHL (14.8%) (P < 0.05). Interval between the onset of RA and LPD development was significantly longer in LPD with p53 gene mutations (median 228 months) than that without mutations (133 months). LPD with p53 gene mutations had more advanced diseases and an unfavorable prognosis than those without mutations. MTX-LPD and non-MTX-LPD show similar findings in clinical characteristics, histology, EBV positive rate, and frequency of Bak gene mutations. Whereas the non-MTX-LPD is distinct from the MTX-LPD in its significantly higher p53 mutation frequency.

Analysis of p53 gene mutations in parapsoriasis

Journal of the European Academy of Dermatology and VenereologyVolume 20, Issue 7 p. 882-883 Analysis of p53 gene mutations in parapsoriasis EB Başkan, Corresponding Author EB Başkan Departments of Dermatology, *Corresponding author, Uludag University Medical Faculty, Dermatology Department, Görükle 16059, Bursa, Turkey, tel. +90 224 442 81 44; fax +90 224 442 92 29; E-mail: bbemel@uludag.edu.trSearch for more papers by this authorB Tunca, B Tunca Medical Biology andSearch for more papers by this authorG Çeçener, G Çeçener Medical Biology andSearch for more papers by this authorŞ Tunalı, Ş Tunalı Departments of Dermatology,Search for more papers by this authorÜ Egeli, Ü Egeli Medical Biology andSearch for more papers by this authorH Sarıcaoǧlu, H Sarıcaoǧlu Departments of Dermatology,Search for more papers by this authorSB Adım, SB Adım Pathology Uludag University Medical Faculty, Bursa, TurkeySearch for more papers by this author EB Başkan, Corresponding Author EB Başkan Departments of Dermatology, *Corresponding author, Uludag University Medical Faculty, Dermatology Department, Görükle 16059, Bursa, Turkey, tel. +90 224 442 81 44; fax +90 224 442 92 29; E-mail: bbemel@uludag.edu.trSearch for more papers by this authorB Tunca, B Tunca Medical Biology andSearch for more papers by this authorG Çeçener, G Çeçener Medical Biology andSearch for more papers by this authorŞ Tunalı, Ş Tunalı Departments of Dermatology,Search for more papers by this authorÜ Egeli, Ü Egeli Medical Biology andSearch for more papers by this authorH Sarıcaoǧlu, H Sarıcaoǧlu Departments of Dermatology,Search for more papers by this authorSB Adım, SB Adım Pathology Uludag University Medical Faculty, Bursa, TurkeySearch for more papers by this author First published: 21 April 2006 https://doi.org/10.1111/j.1468-3083.2006.01556.xRead the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume20, Issue7August 2006Pages 882-883 RelatedInformation

Prognostic implications of p53 gene mutations in bladder tumors.

Alterations in the p53 gene related to neoplastic progression were studied in tumor tissue samples from patients with transitional cell carcinoma and correlated with classic staging parameters. On this basis, biological characterization of the tumor was performed to establish subgroups of patients at high risk and those with a more favorable prognosis. This observational, analytical and cross-sectional study included 115 patients divided into 4 homogeneous groups of 1-control, 2-primary superficial transitional cell carcinoma, 3-recurrent superficial transitional cell carcinoma, and 4-infiltrative transitional cell carcinoma. DNA was obtained from tumor tissue samples and polymerase chain reaction-single strand conformational polymorphism analysis was performed on exons 5 to 9 of the p53 gene. Samples showing mutations were submitted to automatic sequencing. Statistics included bivariate analysis and logistic regression. Of the tumors the 63.8% were superficial and 37.2% were infiltrative transitional cell carcinoma. Of the infiltrative tumors 23.5% (8 of 34) resulted from recurrent transitional cell carcinoma. Mutations were found in samples from 46.8% of patients, all with bladder tumors. There was a trend toward increasing appearance of mutations as the size of the tumor, number of tumor implants, degree of dedifferentiation and stage of local infiltration increased. The presence of mutations in p53 was 2.5 times greater in infiltrative tumors than in low stage and 4.3 times greater in moderate to high grade than in low grade tumors. All mutations found were point mutations and 79.25% provoked severe alterations in protein structure. Mutations in the p53 gene are mainly point mutations that aggregate in hot spots, and provoke genetic instability and substantial changes that alter p53 function, implying a trend to tumor progression and dissemination (with a greater proportion of mutations in high stage high grade tumors). Since a large percentage of bladder tumors are under staged, analysis of p53 gene mutations could be useful as a factor for prognosis and therapeutic decisions.

Mutations of p53 gene exons 4-8 in human esophageal cancer

To characterize the tumor suppressor gene p53 mutations in exon 4, esophageal cancer and adjacent non-cancerous tissues. We performed p53 (exons 4-8) gene mutation analysis on 24 surgically resected human esophageal cancer specimens by PCR, single-strand conformation polymorphism, and DNA sequencing. p53 gene mutations were detected in 9 of 22 (40.9%) esophageal cancer specimens and 10 of 17 (58.8%) adjacent non-cancerous tissues. Eight of sixteen (50.0%) point mutations detected were G-A transitions and 9 of 18 (50.0%) p53 gene mutations occurred in exon 4 in esophageal cancer specimens. Only 1 of 11 mutations detected was G-A transition and 4 of 11 (36.4%) p53 gene mutations occurred in exon 4 in adjacent non-cancerous tissues. Mutation of p53 gene in exon 4 may play an important role in development of esophageal cancer. The observation of p53 gene mutation in adjacent non-cancerous tissues suggests that p53 gene mutation may be an early event in esophageal carcinogenesis. Some clinical factors, including age, sex, pre-operation therapy and location of tumors, do not influence p53 gene mutation rates.

Clinical implications of p53 mutation analysis in bladder cancer tissue and urine sediment by functional assay in yeast.

In the present study we correlate the p53 gene mutations in tumour tissue with urine sediment using a functional assay in yeast, and relate the p53 status to the outcome in a group of patients with transitional cell carcinoma of the bladder. The p53 mutations were found in three of 30 (10%) Ta/T1 tumour tissue samples and in two of 20 (10%) corresponding urine sediments. In the stage T2-T4 tumour p53 mutations were found in tumour tissues and urine sediments in 13 of 31 (42%) and in seven of 18 (39%) samples, respectively. In 80% (8/10) of cases, the p53 mutations found in tumour tissue were re-detected in urine sediment. Median follow-up was at 20 months. Disease recurred in 18 of the 61 patients (30%) with a median time of 5 months. In Ta/T1 tumours the frequency of recurrence was 37% (11/30) compared with 23% (7/31) of T2-T4 tumours. The 3-year overall survival (OS) was 82% (50/61). The p53 status was significantly associated with stage (P = 0.0077, two-sided Fisher's exact test), grade (P < 0.001) and lymph node involvement (P = 0.027). There was an association between the p53 mutations and shorter OS (P = 0.033; log-rank test); however in a multivariate analysis adjusted for stage, grade, lymph node status and age the p53 mutation was not an independent predictor of survival. There was no correlation of the p53 status with decreased disease-free survival (P = 0.8; log-rank test). The data presented indicate that the yeast functional assay is a useful method for p53 gene mutation analysis in tumour tissue and p53 mutation can be re-detected in urine sediment, but further validation of the assay in non-invasive screening for p53 mutations is needed.

Possible distinct molecular carcinogenic pathways for bladder cancer in Ukraine, before and after the Chernobyl disaster

After the Chernobyl accident in 1986, the incidence of urinary bladder cancers in the Ukraine increased gradually from 26.2 to 43.3 per 100,000 people between 1986 and 2001. In the areas of low level but persistent cesium-137 (137Cs) radio-contamination, a unique atypical radiation-related urinary bladder cystitis named 'Chernobyl cystitis', a possible pre-neoplastic condition in humans, has been detected. We have previously documented high incidences of bladder lesions, including severe dysplasias and/or carcinoma in situ, in association with this cystitis and correlating with oxidative DNA damage. To further investigate the molecular mechanisms underlying bladder carcinogenesis with this specific etiology, mutation analysis of p53 gene (exon 5-8) was performed for 11 and 18 paraffin-embedded bladder cancers in Ukrainians, respectively collected before and after the Chernobyl disaster. DNAs were extracted and subjected to nested PCR-single-strand conformational polymorphism analysis followed by direct DNA sequencing, as well as p53 immunohistochemistry (IHC). The incidences of p53 gene mutation were 54.5 and 16.7% for before and after the Chernobyl disaster, respectively, the difference being statistically significant. Also a tendency for higher p53 IHC score was apparent in the earlier group of lesions. No significant difference was noted for the proportions of historical types. These results point to possible distinct molecular carcinogenic pathways of bladder cancer formation, before and after the Chernobyl disaster, on the basis of variation in p53 gene alteration.

High frequency of G/C transversion on p53 gene alterations in breast cancers from Taiwan

p53 gene mutation is a very frequent event in many human cancers and is associated with a poor clinical outcome in breast cancer patients. Analysis of p53 gene mutations can also provide clues to the etiology of tumor formation. The present study was conducted to investigate the p53 mutations in patients with breast cancer from Taiwan. Tumor samples from 119 patients undergoing mastectomy for breast cancer were evaluated. The mutational status of the p53 gene (exons 5–8) was screened by polymerase chain reaction-single strand conformation polymorphism analysis followed by direct sequencing. Of all 119 cases of breast carcinoma, 26 mutations of the p53 gene were found in 22 cases (18.5%). Among these mutations, 78% (20/26) were point mutations with the majority of those being missense mutations (75%, 15 of 20 mutations) and the other 22% (6/26) were frameshift mutations. No significant correlation between p53 mutations and clinicopathological features was found, including HER2 status. Moreover, our results disclosed distinct mutation spectra in excess transversions to transitions (15/21, 71.4% vs. 6/21, 28.6%) with GC to CG dominant (6/15, 40%). Mutation hot spots we identified at codons 167, 185, 186, 210, 265 and 295 have rarely been documented in the literature. These findings showed that p53 gene mutation might contribute to the pathogenesis of breast carcinoma. Furthermore, the different mutation spectrum with high transversions in G:C to C:G may imply that the exogenous mutagens outweigh the endogenous processes in breast cancer in patients in Taiwan.

Analysis of Ki-ras and p53 gene mutations in laterally spreading tumors of the colorectum.

A laterally spreading tumor (LST) is considered to be a specific subtype of superficial colorectal tumors, in view of its characteristic clinicopathological features. We attempted to compare genetic alterations found in LST (>10 mm) with those found in IIa-type adenomas (10 mm or less (small superficial elevated lesion)) and conventional polypoid adenomas (>10 mm). In addition, multiple sampling by microdissection was performed for 14 LST to examine genetic heterogeneity in the Ki-ras and p53 gene mutation patterns. Polymerase chain reaction, single-strand conformation polymorphism and direct sequencing were used to analyze Ki-ras and p53 gene mutations in 73 sporadic colorectal adenomas: 28 LST; 22 IIa-type adenomas; and 23 polypoid adenomas. Ki-ras gene mutations were found more frequently in LST (6/28 tumors) and polypoid adenomas (6/23 tumors) than in IIa-type adenomas (2/22 tumors), although this difference was not statistically significant. The frequency of p53 gene mutations in the 28 LST was 25% (7/28), which was significantly higher than that found in IIa-type adenomas (P < 0.05). However, although p53 gene mutations were found more frequently in LST than in polypoid adenomas, this difference was not statistically significant. Seven LST exhibited a combination of wild-type and mutant-type tumor cells having the p53 gene mutation pattern, whereas a pattern of different Ki-ras gene mutations was found in two of three LST that exhibited Ki-ras gene mutation heterogeneity. We suggest that the LST exhibited a characteristic pattern in terms of the Ki-ras as well as the p53 gene mutation pattern, thereby supporting the hypothesis that LST is a specific subtype of colorectal tumors.