Expression Of Mutant P53 Protein Research Articles

P-Phenylenediamine induced DNA damage in SV-40 immortalized human uroepithelial cells and expression of mutant p53 and COX-2 proteins

p-Phenylenediamine ( p-PD) is the main aromatic amine used in the formulation of hair dyes. Some epidemiologic studies have suggested that the use of p-PD-based hair dyes might be related to increased risk of human malignant tumors including bladder cancer and hematopoietic cancers. However, the toxicity and genotoxicity of p-PD on urothelial cells has not been reported yet. Therefore, we investigated the genotoxicity of p-PD on human urothelial cells and study its association with the expression of oncoproteins p53 and cyclooxygenase-2 (COX-2). Our results revealed that p-PD was able to induce DNA damage determined by Comet assay. In addition, our immunocytochemical and Western blotting results showed that p-PD induced overexpression of mutant p53 and COX-2 in a dose-dependent manner. The relationship between mutant p53 and COX-2 expression shows strong correlation. Furthermore, the accumulation of mutant p53 was linearly correlated with Comet scores. These results suggest that p-PD can induce DNA damage and accumulation of mutant p53 and COX-2 proteins; this may be one of the possible mechanisms that cause genotoxic carcinogenesis in the urothelial cells.

Restoration of wild‐type p53 function in human cancer: Relevance for tumor therapy

In the majority of human cancers, the tumor suppressor activity of p53 is impaired because of mutational events or interactions with other proteins (ie, MDM2). The loss of p53 function is responsible for increased aggressiveness of cancers, while tumor chemoresistance and radioresistance are dependent upon the expression of mutant p53 proteins. Review of the literature indicates that p53 acts primarily as a transcription factor whose function is subject to a complex and diverse array of covalent post-translational modifications that markedly influence the expression of p53 target genes responsible for cellular responses such as growth arrest, senescence, or apoptosis. The ability of p53 to induce apoptosis in cancer cells is believed essential for cancer therapy. Numerous data indicate that p53 dependent apoptosis is a relevant factor in determining the efficacy of anticancer treatments. Thus, the development of new strategies for restoration of p53 function in human tumors is considered an important issue. Two main approaches for restoration of p53 function have been pursued that impact anticancer treatments: (a) de novo expression of wild-type p53 (wt-p53) through gene therapy and (b) identification of small molecules reactivating wt-p53 function. The extensive body of knowledge acquired has identified manipulations of p53 signaling as a relevant issue for successful therapies. In this context, the recognition of p53 status in cancer cells is significant and would help considerably in the selection of an appropriate therapeutic approach. p53 manipulations for cancer therapy have revealed the need for specificity of p53 activation and ability to spare body tissues. Furthermore, the promising results obtained by using molecules competent to reactivate wt-p53 functions in cancer cells provide the basis for the design of new molecules with lower side effects and higher anti-tumor efficiency. The reexpression and reactivation of p53 protein in human cancer cells would increase tumor susceptibility to radiation or chemotherapy enhancing the efficacy of standard therapeutic protocols.

Expression of p73, ER and PR in esophageal carcinoma and precancerous lesions

Objective To test the expression of mutant p73, p53, ER and PR proteins in the esophageal normal mucosa, hyperplasia, dysplasia and squamous cell carcinoma, and research the clinically pathological significance and the correlation, for the early diagnosis, prognostic measure and therapy in clinic.

Apoptosis induced by neoadjuvant chemotherapy in breast cancer

To evaluate the relationship between apoptosis induced by chemotherapy and clinical response in breast cancer. Apoptosis index (AI), mutant p53 and Bcl-2 protein expression were evaluated in 44 breast tumour samples from patients submitted to neoadjuvant chemotherapy. Objective response (OR) to primary chemotherapy was observed in 37 patients (84%) and no response (NR) in seven. AI was measured by the rate of apoptotic cells identified using morphological criteria. p53 and Bcl-2 protein expression were evaluated using an immunoperoxidase staining technique. The median AI change observed between pre-chemotherapy AI and post-chemotherapy AI was 0.84 in the OR group and 0.01 in the NR group, (rho = 0.4; p = 0.006). There was no change in Bcl-2 protein expression following chemotherapy. In the OR group, p53 protein expression was positive in 41.6% of patients before and in 22.2% after chemotherapy (difference = 16.6%; p = 0.03). No change was detected in the NR group. A positive correlation was found between the increase in AI and clinical response to neoadjuvant chemotherapy in locally advanced breast cancer.

Growth inhibitory effects of quercetin on bladder cancer cell

Quercetin, a flavonoid found in many fruits and vegetables, belongs to an extensive class of polyphenolic compounds. Previous studies reported that quercetin inhibits the proliferation of various cancer cells and tumor growth in animal models. We investigated the growth inhibition and colony formation of quercetin on three bladder cancer cells (EJ, J82 and T24). The expression of tumor suppressor genes and oncogenes such as P53, Survivin, PTEN, as well as the methylation status of these genes was also evaluated. We observed that quercetin induced apoptosis in bladder cancer cells in a time- and dose-dependent manner. Quercetin (100 micromolars) significantly inhibited EJ, T24 and J82 cell growth accompanied by an increase in the G0/G1 phase. In all cell lines, quercetin decreased the expression of mutant P53 and Survivin proteins. However, there was no change in the level of PTEN protein. Moreover, the DNA methylation levels of the estrogen receptor (Er-beta), P16INK4a and RASSF1A were strongly decreased (from 35 to 70%) in the quercetin-treated group compared to the control. In conclusion, our study suggested that quercetin inhibits growth, colony formation and hypermethylation of bladder cancer cell lines. Quercetin-induced apoptosis might be associated with a decrease in mutant P53 and Survivin proteins.

Expression of KAI1 gene in non-small cell lung cancer and its relationship with P53

Recent researches have manifested that down-regulation of KAI1 relates to metastasis in various tumors, but its association with non-small cell lung cancer (NSCLC) and the mechanism for its down-regulation are not clear. The aim of this study is to investigate the expression of KAI1 in NSCLC and its relationship with clinicopathological characteristics and mutant P53 protein. The expression of KAI1/CD82 and mutant P53 protein was detected in 48 cases of NSCLC tissues by Western blot, and KAI1 mRNA was detected by RT-PCR method, with 20 cases of pulmonary benign disease tissues and normal lung tissues as control.. The positive rate of KAI1 mRNA was 52% in lung cancer group and 90% in control group, respectively (P < 0.01), KAI1/CD82 was 48% and 85% respectively (P < 0.01), and mutant P53 protein was 65% and 5% respectively (P < 0.01). The positive rate of KAI1 mRNA, KAI1/CD82 and mutant P53 protein closely related to the tumor stages, cell differentiation and lymph node metastasis status (P < 0.05 or P < 0.01). The expression of KAI1/CD82 highly related to KAI1 mRNA (P < 0.01) and mutant P53 protein (P < 0.05), while expression of KAI1 mRNA did not relate to mutant P53 protein expression (P > 0.05). The down-regulation of KAI1 may relate to carcinogenesis, development and metastasis of NSCLC. Its reduction may occur mainly at transcriptional level and correlate with p53 in NSCLC. KAI1 and p53 might be helpful to predict the potential metastasis of NSCLC.

RB18A enhances expression of mutant p53 protein in human cells

RB18A (TRAP220/DRIP205) is a cofactor of transcription. We herein demonstrated that RB18A downregulated p53 and upregulated MDM2 promoters. These RB18A regulations, not modified by p53wt expression, were inhibited by mutant p53 (p53mut) expression, which directly interacts with RB18A D5 domain. In addition, RB18A via its D4 domain, also interacts directly and specifically with MDM2 protein inhibiting p53mut degradation. Altogether, these mechanisms contribute to maintain a high level of p53mut expression in tumor proliferating cells. Therefore, RB18A plays a central role to control p53wt and p53mut protein content and functions in cells through a loop of regulation, which involves MDM2.

Inverse Correlation Between the Expression of O6-Methylguanine-DNA Methyl Transferase (MGMT) and p53 in Breast Cancer

Expression of O(6)-methylguanine-DNA methyl transferase (MGMT), a DNA repair protein, has been associated with tumor resistance to alkylating agents such as cyclophosphamide. Promoter hypermethylation of MGMT is a strong predictor of survival, and expression of mutant p53 protein may be associated with downregulated MGMT expression in brain tumors. In order to clarify further the correlation between MGMT and p53 expression, we investigated the expression levels of both MGMT and p53 in breast cancer. MGMT and p53 expression was examined in tissues from 48 consecutive cases of primary breast cancer patients using immunohistochemical staining with antibodies specific for MGMT and p53. The prognosis for survival was analyzed based on MGMT and p53 immunoreactivity and clinicopathological characteristics. Expression of either MGMT or p53 was classified as negative or positive based on immunohistochemical staining. The expression of MGMT showed a significant inverse correlation with three clinicopathological characteristics, the status of the estrogen receptor, local recurrence and distant metastasis. There was a significant correlation between the expression level of p53 and the lymphatic involvement, estrogen receptor status and distant metastasis. MGMT and p53 were correlated with distant metastasis and local recurrence, but Kaplan-Meier curves did not show a significant difference. MGMT immuno-negative specimens showed a significantly higher expression of p53 (P = 0.026, chi(2) test). p53 may be associated with the regulation of MGMT expression in breast cancers.

Expression of protein p53 in workers occupationally exposed to benzidine and bladder cancer patients.

To study expression of mutant p53 protein in workers occupationally exposed to benzidine and bladder cancer patients. Mutant p53 protein in serum from the workers occupationally exposed to benzidine and bladder cancer patients were determined with Immuno-PCR, while exfoliated urothelial cells in the urine samples were classified with Papanicolau grading. Positive rate of mutant p53 protein increased with the exposed intensity index in workers occupationally exposed to benzidine. The positive rate of mutant p53 protein in bladder cancer patients (83.3%) was significantly higher than that in the group 1 of exposed intensity index. The average scanning integrals of PCR amplified band in the group of bladder cancer patients and group 2 of exposed intensity index were both higher than that in the group 1 significantly. Workers in the groups of different exposed intensity indices were further stratified according to Papanicolau grades. In the group 2 of exposed intensity index, the average scanning integrals of PCR amplified band in the stratum of Papanicolau grade II and III were significantly higher than that in the strata of Papanicolau grade I. And in the group 3 of exposed intensity index, the positive rate of mutant p53 protein in the strata of Papanicolau grade III was higher than that in the strata of Papanicolau grade I significantly. The increase of exposed intensity may not only result in the positive rate of mutant p53 protein, but also the quantity of mutant p53 protein in serum within the low range of benzidine exposure. Once the exposed intensity was beyond that spectrum, the positive rate of mutant p53 protein in serum and the average scanning integrals of PCR amplified band were no longer enhanced with the increase of exposed intensity. There was tight correlation between Papanicolau grade of exfoliated urothelial cells and the positive rate or the quantity of mutant p53 protein for the higher benzidine exposure intensity.

Tumor progression and chemosensitivity to uracil/tegafur in relation to the apoptosis related protens in gastric cancer

4072 Background: Apoptosis related proteins including p53 and p21 regulate cell cycle under exposure of anticancer drugs. The Bax and Mcl-1 gene are members of the Bcl-2 family. Bcl-2 and Mcl-1 are blockers of cell death, whereas Bax and Bcl-Xs are promoters of apoptosis. Methods: To study apoptosis related protein expression and their impact on patient's survival time and chemosensitivity to postoperative UFT [uracil/tegafur 4:1], we examined mutant p53, p21, bax and Mcl-1 protein expression using immunohistochemical staining in 125 surgically resected gastric carcinomas invading the serosa (T3). Results: Expression of mutant p53, p21, Bax and Mcl-1 proteins were detected in 64%, 48%, 39% and 75% of patients, respectively. Mutant p53(+), p21(-) or Mcl-1(+) tumor was frequently observed in more advanced carcinomas. Patients with mutant p53(-), p21(+) or Mcl-1(-) tumor had better survival rates than those with mutant p53(+), p21(-) or Mcl-1(+) tumor, respectively. More p21(+) or Bax(+) cases and less mutant p53(+) or Mcl-1(+) cases were found in differentiated carcinoma. In patients with mutant p53(+), p21(+), Bax(-), or Mcl-1(-) tumor, no survival benefit was obtained by using UFT. In patients with mutant p53 tumor, however, 5-year survival rate of those given UFT was 72%, significantly superior to 35% of those not given the drug (P<0.05). In patients with p21(-) tumor, 54% of patients given UFT survived for 5 year, whereas all patients not given UFT died within 4 years (P<0.05). In patients with Bax(+) tumor, 5-year survival rates were 61% in those given UFT and 31% in those not given UFT (P<0.05). In patients with Mcl-1(+) tumor, 5-year survival rate of those given UFT was 57%, being significantly better than 32% of those not given the drug (P<0.01). Conclusions: These results indicate that the relationship of expression levels of p53, p21, Bax and Mcl-1 is important for predicting the efficacy of postoperative UFT. Therefore, patients with T3 gastric carcinoma should be selected for UFT treatment based on the expression of apoptosis related proteins in tumor cells. No significant financial relationships to disclose.

Transgenic mouse with human mutant p53 expression in the prostate epithelium.

Apoptosis is disrupted in prostate tumor cells, conferring a survival advantage. p53 is a nuclear protein believed to regulate cancer progression, in part by inducing apoptosis. To test this possibility in future studies, the objective of the present study was to generate a transgenic mouse model expressing mutant p53 in the prostate (PR). Transgene incorporation was tested using Southern analysis. Expression of mutant p53 protein was examined using immunofluorescence microscopy. Apoptosis in the PR was evaluated using the Tunnel method. A construct, consisting of the rat probasin promoter and a mutant human p53 fragment, was prepared and used to generate transgenic mice. rPB-mutant p53 transgene incorporation, as well as nuclear accumulation of mutant human p53 protein, was demonstrated. Prostatic intraepithelial neoplasia (PIN) III and IV were found in PR of 52-week old transgenic mice, whereas no pathological changes were found in the other organs examined. PR ability to undergo apoptosis following castration was reduced in rPB-mutant p53 mice as compared to non transgenic littermates. Transgenic rPB-mutant p53 mice accumulate mutant p53 protein in PR, resulting in neoplastic lesions and reduced apoptotic potential in the PR. Breeding rPB-mutant p53 mice with mice expressing an oncogene in their PR will be useful in examining interactions of multiple genes that result in progression of slow growing prostate tumors expressing oncogenes alone to metastatic cancer.

In this issue

In this issue

Nup88 mRNA overexpression is associated with high aggressiveness of breast cancer

The nuclear pore complex protein Nup88 is overexpressed in tumor cells. Immunohistochemical studies have shown that this overexpression is linked to higher aggressiveness of colorectal carcinoma and to enhanced metastatic potential of melanoma cells. However, the antibodies so far developed against Nup88 have the drawback of recognizing a number of other, up to now unspecified antigens besides Nup88. For this reason, we devised the present study on Nup88 expression at the mRNA level. RNA was extracted from fresh tumor tissue corresponding to 122 breast cancer patients. Nup88 mRNA expression was measured by means of differential RT-PCR, standardizing against a constitutive internal control gene (beta-actin). The results were dichotomized into "high" and "low" expression levels, using the median value as cut-off. High Nup88 mRNA expression levels correlated significantly with ductal and tubular histology (p = 0.012), histologic and nuclear grade 3 of tumors (p < 0.001), absence of hormone receptor expression (p < 0.001), expression of the c-erb-B2 oncogene (p < 0.001), expression of mutant p53 protein (p < 0.001), high proliferation (defined by Ki67 labeling index >20%, p < 0.001), DNA aneuploidy (p < 0.001) as well as the most important ominous clinical prognostic factor, axillary node invasion (p < 0.001). We also found an inverse correlation (p < 0.001) with expression of the H-MAM (mammaglobin) gene, a marker of low biologic and clinical aggressiveness of breast cancer. All of these factors, without exception, define a highly aggressive tumor phenotype. These findings appear to be specific to Nup88 and not to nuclear pore proteins in general. Indeed, analysis of Nup107 (which is a limiting component of the nuclear pore complex) under the same conditions in the same tumors did not yield comparable results.

Inhibition of mutant p53 expression and growth of DMS-153 small cell lung carcinoma by antagonists of growth hormone-releasing hormone and bombesin.

We investigated the effects of growth hormone-releasing hormone (GHRH) antagonists, JV-1-65 and JV-1-63, and bombesin/gastrin-releasing peptide (BN/GRP) antagonist RC-3940-II on DMS-153 human small cell lung carcinoma xenografted into nude mice. Treatment with 10 microg/day JV-1-65 or RC-3940-II decreased tumor volume by 28% (P < 0.05) and 77% (P < 0.01), respectively, after 42 days compared with controls. Combination of JV-1-65 and RC-3940-II induced the greatest inhibition of tumor proliferation (95%; P < 0.01), suggesting a synergism. Western blotting showed that the antitumor effects of these antagonists were associated with inhibition of the expression of the mutant tumor suppressor protein p53 (Tp53). Mutation was detected by sequence analysis of the p53 gene at codon 155: ACC [Thr] --> CCC [Pro]. Combination of JV-1-65 and RC-3940-II decreased the levels of mutant p53 protein by 42% (P < 0.01) compared with controls. JV-1-65, JV-1-63, and RC-3940-II, given singly, reduced mutant p53 protein expression by 18-24% (P < 0.05). Serum insulin-like growth factor (IGF)-I levels were diminished in animals receiving GHRH antagonists. mRNA levels for IGF-II, IGF receptor-I, GRP receptor, and EGF receptor in tumors were significantly decreased by combined treatment with JV-1-65 and RC-3940-II. DMS-153 tumors expressed mRNAs for GHRH and GHRH receptor splice variants 1 and 2, suggesting that GHRH could be an autocrine growth factor. Proliferation of DMS-153 cells in vitro was stimulated by GRP and IGF-II and inhibited by JV-1-65. This study indicates that GHRH antagonists and BN/GRP antagonist inhibit the growth of DMS-153 small cell lung carcinoma concomitantly with the expression of mutant Tp53, which might uncouple the signal transduction pathways for cell growth stimulation.

Molecular characterization of oncostatin M-induced growth arrest of MCF-7 cells expressing a temperature-sensitive mutant of p53.

Our previous studies have shown that treatment of MCF-7 breast cancer cells with cytokine oncostatin M (OM) results in a growth arrest and a concurrent decrease in p53 expression. It remains to be determined whether these two important events are directly connected, as changes in p53 protein levels can lead to variable biological outcomes. In this study we have generated stable cell lines (MCF7-ptsp53) that express p53Val135 a p53 temperature-sensitive mutant. We demonstrate that overexpression of the wildtype (wt) p53 at permissive temperature in MCF7-ptsp53 cells leads to growth arrest at the G2-M phase of the cell cycle. Inhibition of endogenous p53 function with the expression of mutant p53 protein at non-permissive temperature did not affect the OM-induced G1 cell cycle arrest. Microarray studies were further carried out to identify p53- and OM-regulated genes that mediate the G2/M or G1 cell cycle arrest. We show that the expression of p21 was upregulated and expressions of cdc2, cyclin B2 and protein regulator of cytokinesis 1 (PRC1) were suppressed by overexpression of the wt p53 in MCF7-ptsp53 cells at the permissive temperature. In contrast, OM treatment caused coordinate changes of mRNA expression of several cell cycle components including c/EBPdelta, cdc20, and thymidine kinase 1 (TK1) that mainly affect G1-S phase transition. All together, our results suggest that the downregulation of p53 transcription may be involved in some other cellular changes induced by OM but it is not directly connected to the antiproliferative activity of OM per se.

Short-Chain Fatty Acids Inhibit Invasive Human Colon Cancer by Modulating uPA, TIMP-1, TIMP-2, Mutant p53, Bcl-2, Bax, p21 and PCNA Protein Expression in an In Vitro Cell Culture Model

High intakes of dietary fiber or resistant starches have been associated with a lower incidence of colon cancers. Because short-chain fatty acids (SCFA) such as butyrate are produced in the colonic lumen by the bacterial fermentation of dietary fibers and resistant starches, we hypothesized that SCFA may inhibit the development of invasive human colon cancers. To test this hypothesis, primary human invasive colonocytes were isolated from fresh surgical specimens and treated with 0.01 mol/L acetate, propionate or butyrate; cell invasion, cell adhesion, F-actin polymerization, urokinase plasminogen activator (uPA), tissue inhibitor matrix metalloproteinase (TIMP)-1, TIMP-2 and mutant p53, Bcl-2, Bax, p21 and proliferating cell nuclear antigen (PCNA) protein expression levels were examined. Although each of the SCFA tested significantly reduced primary cell invasion, butyrate was the most potent, inhibiting primary invasive human colon cancer invasion by 54% (P < 0.0001). The effects of SCFA on primary cell invasion appeared to be independent of cell adhesion and F-actin polymerization but dependent on the inhibition of uPA (P < 0.05) and the stimulation of TIMP-1 and TIMP-2 activities (P < 0.05). Protein expression levels of mutant p53, p21, Bax, Bcl-2 and PCNA were significantly altered by each of the SCFA tested (P < 0.05). These data indicate that SCFA inhibit invasive human colon cancer by modulating proteolytic uPA and antiproteolytic TIMP-1 and TIMP-2 activities, but their mechanisms of action on tumor suppression, apoptosis and growth arrest may differ.

The Prognostic Significance of P-glycoprotein,Mutant p53 Protein and Epidermal Growth Factor Receptor Expression in Primary Transitional Cell Carcinoma of Bliadder

The Prognostic Significance of P-glycoprotein,Mutant p53 Protein and Epidermal Growth Factor Receptor Expression in Primary Transitional Cell Carcinoma of Bliadder

The relationship between microvessel count and the expression of vascular endothelial growth factor, p53, and K-ras in non-small cell lung cancer.

Using immunohistochemical staining, we studied the relationship between the microvessel count (MC) and the expression of K-ras, mutant p53 protein, and vascular endothelial growth factor (VEGF) in 61 surgically resected non-small cell lung cancers (NSCLC) (42 squamous cell carcinoma, 14 adenocarcinoma, 2 large cell carcinoma, 2 adenosquamous carcinoma, and 1 mucoepidermoid carcinoma). MC of the tumors with lymph node (LN) metastasis was significantly higher than that of tumors without LN metastasis (66.1+/-23.1 vs. 33.8+/-13.1, p<0.05). VEGF was positive in 54 patients (88.5%). MC was 58.1+/-25.2 (mean+/-S.D.) in a x200 field, and it was significantly higher in VEGF(+) tumors than in VEGF(-) tumors (61.4+/-23.7 vs. 32.9+/-23.8, p<0.05). VEGF expression was higher in K-ras-positive or mutant p53-positive tumors than in negative tumors (p<0.05). MC was significantly higher in K-ras(+) tumors than in K-ras(-) tumors, although it did not differ according to the level of mutant p53 protein expression. Survival did not differ with VEGF, mutant p53, or K-ras expression, or the level of MC. In conclusion, there is a flow of molecular alterations from K-ras and p53, to VEGF expression, leading to angiogenesis and ultimately lymph node metastasis. Correlations between variables in close approximation and the lack of prognostic significance of individual molecular alterations suggest that tumorigenesis and metastasis are multifactorial processes.

Immunohistochemical detection of mutant p53 protein in small-cell lung cancer: relationship to treatment outcome

We investigated the expression of mutant p53 proteins in small-cell lung cancer (SCLC) immunohistochemically, by identification of stabilized mutant p53 proteins with a much longer half-life than the wild-type protein. Of 103 tumor specimens obtained by transbronchial tumor biopsy for histologic diagnosis, 52 (50%) showed positive staining for p53 protein with a p53 monoclonal antibody, DO-1. Positive staining for p53 protein was not correlated with age, sex, performance status, lifetime cigarette consumption, serum concentration of neuron-specific enolase and extent of disease. Complete response rates in patients with a mutant p53 protein-positive tumor were significantly lower than those in p53-negative patients (25% versus 59%; P=0.0005, by chi-square test). Similarly, survival periods in patients with a mutant p53 protein-positive tumor were significantly shorter than those in mutant p53-protein-negative patients (10.8 months versus 20.6 months; P=0.0001, by generalized Wilcoxon test). Multivariate analysis using Cox’s proportional hazards model revealed that the presence of mutant p53 protein is an independent factor associated with differences in overall survival (hazards ratio=2.72; 95% confidence interval, 1.71–4.34; P=0.0001). These observations suggest that the expression of mutant p53 proteins in SCLC may be an important factor predicting poor prognosis.

Diffuse Mode of Tumor Cell Invasion and Expression of Mutant p53 Protein But Not of p21 Protein Are Correlated with Treatment Failure in Oral Carcinomas and Their Metastatic Foci

Lack of control of metastatic foci is the most prevalent cause of death in patients with oral carcinomas, and it is important for tumor control to identify the factors that predispose patients to death. In the present study, we examined 225 patients with oral squamous cell carcinoma and investigated the immunohistopathological characteristics of 43 tumors that led to death, comparing them with those of the non-lethal tumors. In the 43 patients, lack of control of the primary site, lymph node and distant metastatic tumors were noted in 20, 18 and 16 patients, respectively. The mode of tumor cell invasion was closely correlated with death. The diffuse invasion modes of grades 4C and 4D were observed in 15 (34.9%) of the 43 tumors with a poor outcome and in 35 (19.2%) of the 182 controlled tumors (p < 0.02). The expression of p53 was highly correlated with death. Of the tumors with poor prognosis, p53 protein was expressed in 32 tumors (76.2%). However, p53 protein expression was observed in 52.7% of the tumors with good prognosis (p < 0.02). In contrast, the expression of p21 protein in the well-controlled tumors (30.4%) was almost equal to that of the 43 lethal tumors (26.2%). Compared with the ratios of local recurrence, metastases and their treatment failures in the p53-negative grade 1 and 2 tumors, those in the mutant p53-positive grade 3, 4C and 4D tumors were mostly high. These results indicate that measuring p53 protein expression and evaluating the mode of tumor cell invasion are important for oral carcinoma therapy because the expression of mutant p53 protein and the diffuse modes of tumor cell invasion indicate a predisposition toward a poor prognosis.